[From the U.S. Government Printing Office, www.gpo.gov]







                                                  _''XS@@ESSING
                   A M@ANUAL-... VQ
                    RES_T        RED'. A            NATURAL
                         C, -OAS   :T-A-L- WETLANDS


                                WITH EXAMPLES FROM

                                SOUTHERN CALIFORNIA





                                           by the


                     Pacific Estuarine     Research Laboratory
                                          (PERL)


                                     Biology Department
                                  San Diego State University
                               San Diego, California 92182-0057

                                           1990





                        A Publication of the California Sea Grant College







    GC
    57.2                                                      CZIC COLLECTION
     C313
    no.021























                                                                   Dedicated to the memory of

                                                                     Dr. Millicent Quarnmen,
                                                                        estuarine researcher,
                                                              who insisted that restored wetlands
                                                                    be assessed on the basis of
                                                                          their functioning.










                         Cite as: Pacific Estuarine Research Laboratory. 1990. A manual for assessing restored
                                    and natural coastal wetlands with examples from southern California. California
                                    Sea Grant Report No. T-CSGCP-021. La Jolla, California.






                                              U . S . DEPARTMENT OF COMMERCE NOAA
                   COW-                       COASTAL SERVICES CENTER
                                              2234 SOUTH HOBSON AVENUE
                                              CHARLESTON , SC 29405-2413



        Lo


                                              Property of CSC Library







                                                                      Contributions


                               Principal Author, Compiler                                             Technical Advice
                          Joy B. Zedler, Ph.D. Wetland and estuarine                    John Boland, Ph.D.           Weiland ecologist,
                            ecologist, with interest in all aspects of salt               reviewed the section on bird sampling
                            marsh structure and functioning. Responsible                Brian Fink, M.S. Coastal plant propagation
                            for most of the writing--and all of the effors.               expert, advice on salt marsh bird's beak
                                                                                        Theodore Griswold, M.S. Wetland
                                        Section Author                                    biologist; data analysis and interpretation.
                                                                                        Barbara Kus, Ph.D.             Avian ecologist,
                          Ren6 Langis, Ph.D. Weiland ecologist, with                      provided methods for bird study
                            expertise in assessing nutrient dynamics          *         Christopher S. Nordby, M.S.             Authority
                            Principal author of Section IU: Soils; co.                    on wetland fishes and invertebrates
                            author of Section IV.2: Water quality;                      Kathy Williams, Ph.D. Insect ecologist,
                            collaborator on the San Diego Bay case study;                 provided methods for insect study
                            and reviewer of most sections.

                                                                                                      Data Collection
                                   Illustrations: Mark Lung                             Patrice Ashfield.      Birds, Tijuana Estuary,
                                 Copy Editing: Bruce Nyden                                Sweetwater River Wetland Complex
                                                                                        Melissa Bukowski. Geographic Information
                            Assistance with manuscript format:                            System, Tijuana Estuary
                                  Julie Reynolds, Dawn Makis                            Max Busnardo. Vegetation map, Tijuana Estuary
                                                                                        John Cantilli. Soil sulfide dynamics, soil redox
                                                                                        Carol Digiorgio. Benthos, Tijuana Estuary
                                                                                        Robert Espinoza. Herpetology, Tijuana Estuary
                                        Agency Advice                                   Peggy Fong. Algal dynamics at Tijuana Estuary
                                                                                          and in experimental mesocosms
                              US Fish and Wildlife Service, US Army                     Jeff Haltiner, Ph.D. Hydrologic expertise,
                          Corps of Engineers, National Marine Fisheries                   Sweetwater River Wetland Complex
                          Service, State Coastal Conservancy, California                Kim Johnson. Insects, Tijuana Estuary
                          Coastal Commission, California Department of                  Sharon Lockhart. Weiland habitat area data for
                          Parks and Recreation, California Department of                  San Diego County
                          Transportation.       Note:     Input from staff              Paul Little. Water quality, Tijuana Estuary, Los
                          members does not imply agency endorsemen .                      Peflasquitos Lagoon
                                                                                        Ricardo Martinez-Lara. Polychaete identification
                                                                                        David Nelson. Geographic Information System,
                                                                                          Tijuana Estuary
                                                                                        Jeff Newman. Birds, Tijuana Estuary
                          Research and Publication Support                              Regina Rudnicki. Macroalgae, Tijuana Estuary
                                                                                          and in enrichment experiments
                              This work is a result of research sponsored               Sue Rutherford.        Epibenthic invertebrates,
                          in part by the National Oceanic and Atmospheric                 Sweetwater River Weiland Complex
                          Administration (NOAA), National Sea Grant                     Theresa Sinicrope. Water quality, Sweetwater R.
                          College Program, Department of Commerce,                        Weiland Complex
                          under grant number NA85AA-D-SG140, project                    Kendra Swift. Restored marsh assessment, San
                          number R/CZ-82, through the California Sea                      Diego Bay wetlands
                          Grant College, in part by NOAA Office of                      Ernie Taylor. Mammals, Tijuana Estuary
                          Coastal Zone Management, Marine and Estuarine                 John Tiszler. Vegetation map, Tijuana Estuary
                          Management Division, under contract no. 85-                   Nils Warnock. Birds, Tijuana Estuary
                          0236-85-072-A, and in part by the California                  Philip Williams, Ph.D. Hydrologic expertise,
                          State Resources Agency, the California                          Tijuana Estuary
                          Department of Transportation, and the California              Richard Wright, Ph.D. Geographic Information
                          State Coastal Conservancy.                                      System, Tijuana Estuary
                                                                                        Malgorzata Zalejko. Nitrogen fixation, San
                              Support for publication was provided in part                Diego Bay wetlands
                                by the NOAA Coastal Ocean Program.                      Emily Zedler, Sarah Zedler. Data entry, proofing






                                                                          Table of Contents








                              1. Introduction                  .............................................................................                 I

                            11.      Strategies for wetland construction, restoration, enhancement                                                .......    3

                                     1. Concerns          ..............................................................................                     3

                                     2.   Rationale for functional assessment                  ................................................              5

                                     3.   Objectives of assessment              ............................................................                 6

                                     4.   Criteria for "successful mitigation" as required in San Diego Bay                                  ............. 12

                                     5.   Reference wetlands and reference data sets                     .......................................          13

                                     6.   How should major restoration programs be undertaken?                               .......................      17

                          III.       Case study: Sweetwater River Wetlands Complex                                           .......................      19

                          IV.        Sampling methods and comparative data from natural wetlands                                                   .....  35

                                     1. Hydrologic functions               ................................................................               37

                                     2.   Water quality        ..........................................................................                 40

                                     3.   Soils: Substrate qualities and nutrient dynamics                    ..................................          44

                                     4.   Vegetation composition and growth                            ................................................   52

                                     5.   Marsh insects: Pollinators, predators, and prey                              .................................. 65

                                     6.   Aquatic invertebrates: Food chain support                              ........................................ 69

                                     7.   Fishes: Community dynamics, controlling factors                           ..............................        76

                                     8.   Birds    ...................................................................................                    81

                                     9.   Reptiles and amphibians             .............................................................               89

                                    10.   Mammals        ..............................................................................                   90

                            V. Recommendations for minimum monitoring                                            ................................         92

                          VI. Literature cited                      .........................................................................             96






                                                     Introduction


                                                                  experience needed to understand complex
                       1. Introduction                            ecosystems. In addition to drawing upon
                                                                  their expertise, the text includes
                   This manual presents recommenda-               information that has been summarized for
               tions for assessing the structure and.             various. conferences on wetland
               functioning of coastal wetlands, with              restoration (e.g., Zedler et al. 1988,
               emphasis on salt marshes and tidal                 1990), as well as information from
               creeks. While the recommendations can              manuscripts in progress (e.g., Nordby
               be applied to many situations, the main            and Zedler, in press; Langis et al., in
               purpose of the manual is to standardize            press) and recent studies carried out at
               methods of assessing restored, enhanced,           Tijuana Estuary
               or constructed wetlands.                               The need. Thorough evaluation
                   The basic premise is that a man-               procedures that can stand the test of
               made wetland should provide the same               scientific review are clearly needed.
               values as the region's natural wetland             Quammen (1986) recommended two
               ecosystems. This is especially important           types of monitoring to evaluate whether
               in southern California, where native               created wetlands compensate for the
               wetland habitats have dwindled to small,           losses in natural wetlands: first, an
               disturbed, isolated remnants, most of              assessment of compliance with resource
               which can no longer sustain the                    agency recommendations and, second,
               biodiversity that once characterized this          long-term, scientific evaluation to test
               region. Our remarks often emphasize                predictions and hypotheses concerning
               rare native species, but we do not suggest         the development of natural ecosystem
               that management be restricted to target            functions. We suggest that the two
                                                                  assessment goals be merged, such that
               species (Zedler 1984). The threatened              "compliance" becomes the successful
               and endangered species that often drive            "replacement of lost wetland functions."
               restoration and management efforts are             Projects would be , considered in
               the obvious symptoms of more subtle                compliance with mitigation policies once
               changes in ecosystem structure and                 the constructed or modified wetland
               function A whole-system approach at                shows high potential for achieving natural
               the regional scale is needed to assess,            functional attributes. Furthermore, the
               understand, and manage coastal southern            information base upon which judgments
               California wetlands.                               of compliance/success are made should
                   With restoration and enhancement               be able to withstand scientific review.
               plans growing in number and size, it is            The problems resulting from erroneously
               imperative that we understand how well             concluding that a project is successful are
               such projects are working if we are to             too great for the assessment process to be
               achieve. the overall objective of                  casual or short-term. A margin of safety
               maintaining regional biodiversity. If              is essential.
               most projects are failing to provide the               From the ecological perspective,
               habitat required for native species to             determining when a constructed wetland
               persist in perpetuity, we must find better         has attained the functions of a natural
               restoration techniques, and we must                wetland is neither simple nor quick. As
               certainly halt mitigation practices that           Odum (1987, p. 67) points out, "Too
               allow the "replacement" of native wetland          frequently, the success or failure ... is
               habitat with artificially constructed.             determined after a year or two's growth
               wetlands.                                          of the original, planted vegetation.
                   The list of scientists whose work and          Unfortunately, dramatic unanticipated
               advice have contributed to this manual             changes may occur over the ensuing
               indicates the broad range of skills and            years .... it is not uncommon for the plant
                                                                  community to become invaded and







                                                               Introduction


                        dominated by aggressive 'disturbance
                        species'.... The long-term result may be
                        a wetland environment which has limited
                        functional value for wildlife habitat
                        support or nutrient processing and which
                        lacks aesthetic attractiveness to the degree
                        originally planned." Likewise, Broome
                        et al. (1987, p. 197) concluded that
                        monitoring a constructed wetland for four
                        growing seasons was insufficient to
                        determine "if the created marsh reaches
                        equivalent levels of production for all
                        plant species and remains self-
                        sustaining."

                            Organization of this manual.
                        The rationale for requiring constructed
                        wetlands to meet strict assessment criteria
                        is developed in Section II. A case study
                        of the Sweetwater River Wetlands
                        Complex follows (Section III). For this
                        case, functional criteria were mandated by
                        resource agencies, and the Pacific
                        Estuarine Research Laboratory was
                        requested to undertake the detailed
                        assessment. The assessment is not yet
                        complete, but results to date show -how
                        the 4-5-year-old wetlands compare to
                        natural wedand remnants.

                            The assessment methods are grouped
                        under ten attributes of coastal wetlands
                        (Section IV). For each component of the
                        ecosystem, the reasons for study and
                        assessment are provided, followed by
                        methods recommended by PERL.

                            Recommendations for the minimum
                        sampling effort needed for monitoring
                        constructed wetlands are provided in
                        Section V. Reference data and sources of
                        additional information are then given.

                            The manual is not intended to be a
                        final statement, but a working document                                 V.
                        that will continue to evolve as our
                        knowledge of coastal wetlands advances.
                        In all applications of the work, users
                        should check with PERL to insure that
                        the latest information is in hand.





                  Strategies for wetland construction, restoration and enhancement


                        11. Strategies for                                Too many projects have emphasized
                                                                      single-species management. The planting
                   wetland construction,                              of mangroves, cordgrass, or eelgrass
                         restoration and                              seems to have become synonymous with
                                                                      tidal wetland restoration, and transplant
                           enhancement                                survival rates have become measures of
                                                                      "success." In southern California, the
                               1. Concerns                            endangered species law has had a curious
                                                                      impact on restoration activities--it has
                     Coastal wetland restoration is an                tended to suggest single-species man-
                  active endeavor in many regions of the              agement and to imply that one wetland
                  country. New habitats are being con-                type should be modified to meet the needs
                  structed using dredge spoils, grading of            of a target species. Thus, we have seen
                  topography, or other techniques.                    proposals to plant cordgrass in pickle-
                  Wetland construction and restoration                weed marshes, as mitigation for habitat
                  projects are often initiated to offset or           destruction, because cordgrass provides
                  mitigate impacts of wetland destruction.            habitat for the federally endangered light-
                                                                      footed clapper rail. However, pickle-
                  When uplands are excavated to construct             weed provides habitat for the State-listed
                  habitats as replacements for lost wet-              Belding's Savannah sparrow, and con-
                  lands, the question is--are the lost wet-           version of one vegetation type to another
                  land values replaced? When existing                 does not constitute ecosystem enhance-
                  wetlands are modified to restore or                 ment.
                  enhance wetland values, two questions
                  arise--are existing values maintained and              We question the hypothesis that
                  are additional values provided? As per-             constructed wetlands are carrying out the
                  ceptions of success or failure have                 broad range of natural wetland function5.
                  become more controversial, two things               Unfortunately, existing data are inade-
                  have happened--criteria for project com-            quate for testing this hypothesis.
                  pliance have become more, detailed (as              Evaluations of both natural and con-
                  indicated by more complicated permit                structed ecosystems have emphasized
                  requirements issued by the US Army                  structural, rather than functional,
                  Corps of Engineers), and researchers                attributes. Furthermore, most of the
                  have become more interested in studying             structural data are for plants. Fewer
                  man-made systems.                                   evaluations of man-made wetlands have
                     Wetland scientists around the country            considered the animal components.
                  (cf. regional reviews in Kusler and                    Three other factors add to the diffi-
                  Kentula 1989, Strickland 1986, Good                 culty of comparing man-made and natural
                  1987, Zelazney and Feierabend 198.7) are            system functions. First, there may not be
                  concerned that restoration and habitat              suitable models with which to compare
                  construction attempts are not replacing             constructed systems--most coastal wet-
                  lost wetland values. Milton Weller of               lands are already modified; their hydro-
                  Texas A&M states (in Kusler and Kentula             logic regimes (inundation and salinity
                  1989), "In most situations we can                   patterns) have probably changed dramati-
                  provide the environmental needs to allow            cally in the past century, and key species
                  dominant wetland plants and animals to              may already have been eliminated. Is it
                  succeed, and the product will satisfy               sufficient to strive for conditions that now
                  many if not most viewers. We cannot,                exist in wetland remnants, or must we
                  however, expect to replace the complex              understand what conditions allowed those
                  and diverse natural systems that are a              wetland ecosystems to develop? The
                  product of many centuries of evolution              latter seems to be necessary for plant
                  and randomness   ......                             communities where population establish-

                                                                3






                        Strategies for wetland construction, restoration and enhancement


                        ment limits biodiversity. If we lack the            Sometimes, mitigation is required but
                        necessary blueprints for wetland devel-             never implemented. A recent evaluation
                        opment, we can't expect to construct a              of I I freshwater wetlands constructed in
                        system that mimics nature.                          Oregon included data on hydrology
                                                                            (using the presence of water and saturated
                            Second, the functions of natural                soil as indicators), to ography (slope),
                                                                                                   . p
                        models have not been thoroughly studied.            and plant species occurrences (Gwin and
                        We have far more information on the                 Kentula 1990). The vegetation at the
                        composition of benthic: macroinvertebrate           constructed wetlands differed greatly
                        communities than on their psQ by shore-             from species lists given in the permit file.
                        birds and other predators. There is con-            Volunteer species (those not on the
                        siderable information on nutrient levels in         planting list) made up 93-100% of the
                        salt marsh soils, but less understanding            species present (ibid.). Similar results
                        of the sources and rates of inflow and              were found in evaluations of Florida
                        outflow. Studies of one important pro-              wetlands (Kentula, pers. comm.). The
                        cess, i.e. the net flux of detritus, suggest        general conclusion is that the strucutral
                        that results differ from place to place.            attributes of created wetlands are not as
                        Both the direction of net movement and              planned.
                        the magnitude of organic matter flux vary
                        considerably from wetland to wetland,                   With recognition of these problems,
                        and even from site to site within a given           there is increasing demand for improved
                        system.                                             planning, better project implementation,
                                                                            and monitoring of vegetation establish-
                            Finally, there hasn't been sufficient           ment. Still, there is continuing concern
                        time for constructed wedand ecosystems              that constructed wetlands do not replace
                        to mature--hence, it is difficult to assess         lost functional values and that we don't
                        their future potential for performing               know how to correct the situation.
                        natural wetland functions. Few man-
                        made systems have been in place "n                      Two representatives of the U.S. Fish
                        monitored for more than 5 years. While              and Wildlife Service (Holmberg and
                        it may'be possible to construct tidal               Misso 1986, p. 11) acknowledge that
                        wetlands that eventually mimic the func-            "...large-scale artificial wetland creation
                        tions of natural wetlands, judgments are            as a viable method of replacing functional
                        often made after only 1-3 years. Because            natural wetlands has not been docu-
                        we don't know how long it takes, long-              mented." Likewise, the Environmental
                        term assessments must be planned and                Protection Agency has a "conservative
                        continued until we are reasonably confi-            policy" on mitigation because of the
                        dent that expectations have been met. An            scientific uncertainty associated with
                        additional reason for long-term assess-             man-made wetlands (Ciupek 1986).
                        ment is that single measurements (one-              Quarnmen (1986) reviewed several
                        time or one-year data sets) are.unlikely to         reports on mitigation and concluded
                        describe salt marsh structure and func-             "...that compliance is low and that the
                        tioning adequately, because of high tem-            effectiveness of restoration to compensate
                        poral variability in climate and wetland            for wetland losses cannot yet be
                        responses. Low plant biomass in one                 determined."
                        year may indicate poor potential for salt
                        marsh development, or it may simply                     The question is, what should be
                        reflect a year of below-average growing             done? Golet (1986) recommends that
                        conditions.                                         regulatory agencies take a conservative
                                                                            stance on mitigation by rejecting propos-
                           Many salt marsh mitigation efforts               als where loss of wetland is avoidable
                        have problems. In some cases, failures              and reject proposals that result in net
                        are due to poor planning; in others, plans          losses of wetland area.        Instead, he
                        are not properly implemented.                       favors protecting wetlands in their natural


                                                                       4





                    Strategies for wetland construction, restoration and enhancement


                    state and requiring any replacement wet-              irreversibly, and threatened species may
                    lands to "recreatei as nearly as possible,            move closer to extinction. However, the
                    the original wetlands in terms of size,               risks are less if mitigation projects are
                    type, geographic location, and setting     ......     mistakenly judged to be failures (i.e., if
                    Quarnmen (1986) recommends clearly                    wetland functions can be replaced but we
                    stated objectives and design criteria for             don't realize it). It is better to be cautious
                    mitigation wetlands, with monitoring to               than to assume success prematurely if we
                    be conducted and reported. Good (1987,                are to prevent the net loss of in-kind
                    p. 107) calls for "More systematic moni-              resources, as required by mitigation
                    toring and evaluation of existing and                 policy (US FWS 1988). Conclusive evi-
                    soon- to- be-constructed mitigation pro-              dence that constructed wetlands can
                    jects ... to expand our knowledge base.               replace natural wetlands would facilitate
                    Experiments need to be incorporated into              restoration and enhancement efforts.
                    wetland restoration projects to evaluate              Conclusive evidence that certain mitiga-
                    our hypotheses about what does and does               tion procedures canno maintain resources
                    not work. Documentation and sharing of                would reduce economic losses by helping
                    successes and especially failures is                  to resolve conflicts early in the planning
                    needed, not only among agencies, but in               process.
                    the published literature."
                                                                              Disillusionment with the functioning
                        To assist in the evaluation and docu-             of restored marshes has led to stricter
                    mentation of mitigation efforts that are              goals for mitigation and enhancement
                    already underway, and thus to improve                 projects in coastal wetlands and the need
                    the scientific basis for accepting or reject-         for clearer methods of assessing
                    ing mitigation plans, we developed these              "success." Functional, in addition to
                    recommendations for assessing how well                structural, attributes of salt marshes are
                    constructed wetlands replace the func-                being emphasized by both researchers
                    tions of natural wetlands in southern                 and resource agencies in southern
                    California. While other assessment                    California. A marsh constructed by
                    protocols have been developed (e.g.,                  California Department of Transportation
                    Habitat Evaluation Program of the US                  as mitigation for highway expansion must
                    FWS; Adarnus and Stockwell 1983;                      provide self-sustaining populations of
                    Adamus et al. 1987), there is urgent need             plants (including an endangered annual
                    to tailor procedures to the special environ-          hemiparasite), vegetative cover that has
                    ments of this and region. Just as the list            resilience and nitrogen-fixing capability,
                    of wetland functions needs to be refined              and food chain support functions for
                    for the region's rare and threatened                  wetland-dependent endangered birds.
                    habitats, so do the procedures for                    The assessment protocol includes the
                    evaluating their presence.                            analysis of soil processes (decompo-
                                                                          sition, organic matter accumulation,
                                                                          nitrogen fixation, nitrogen trapping,
                                                                          sulfide accumulation) and long-term
                      2. Rationale for functional                         monitoring of transplant expansion rates,
                                  assessment                              reproductive potential of -the endangered
                                                                          plant, and h abitat- specific uses by
                                                                          invertebrates, fishes, and birds. In this
                        What constitutes "successful" mitiga-             coastal region with many endangered
                    tion is highly controversial (Strickland              species, functional values of lost wet-
                    1986, SF BCDC 1988, Zedler 1988a,b),                  lands must be replaced in accordance with
                    and judgments may differ depending on                 new and stricter methods of assessing
                    the evaluation criteria used and the refer-           11success."
                    ence data or comparison sites. If mitiga-
                    tion projects are erroneously judged to be
                    successful, natural resources may be lost


                                                                     5





                       Strategies for wetland construction,                    restoration and enhancement


                                                                               a. Provision of habitat for wetland-
                        3. Objectives of assessment'                                dependent species
                                                                               b. Support of food chains
                           Scientists and managers recognize                   c. Transformation of nutrients
                       three classes of functional values for the              d. Maintenance of plant populations
                       nation's wetlands (Adamus and                           e. Resilience (ability to recover from
                       Stockwell 1983)- hydrologic functions                        disturbances)
                       (e.g., flood peak reduction, shoreline                  f. Resistance to invasive species (plant
                       stabilization, groundwater recharge),                        or animal)
                       water guality improvement (sediment                     9. Resistance to herbivore outbreaks
                       accretion, nutrient uptake), and food                   h  Pollination
                       chain support (habitat and food, espe-                  i  Maintenance of local gene pools
                       cially for commercially important fish and              j  Access to refuges during high water
                       shellfish and for esthetically appreciated              k  Accommodation of rising sea level.
                       birds). Many of these functions are less
                       important in southern California's salt                  a. Provision of habitat for
                       marshes (National Wetland Technical                  wetland -dependent species. For a
                       Council 1985, Onuf et al. 1978), because             region with many rare and threatened
                       they are small in size (with little area to          species, this is the most valued coastal
                       slow flood waters), and located on the               wetland function. Several species of
                       coast and not upstream of potable water              birds, mammals, insects, and a few plant
                       supplies.                                            species are frequent management targets,
                                                                            with maintenance of the entire ecosystem
                          For southern California, the decline in           recognized as an essential management
                       quantity and quality of our coastal wet-             goal.
                       lands has increased the importance of
                       providing habitat for communities of                     For the light-footed clapper rail
                       organisms that can live nowhere else;                (Rallus longirostris levipes), the lower
                       several wetland species, including plants,           marsh provides tall, dense cordgrass for
                       invertebrates, fishes, birds, and mam-               cover and nesting sites, frequent tidal
                       mals, are threatened with extinction.                inundation to deter mammalian predators,
                       Although providing habitat for rare and              litter in the form of weaving materials for
                       endangered species is often the manage-              nest construction, sufficient area for
                       ment goal, mitigators have not been                  territory establishment, and access to
                       required to guarantee their presence'                food. In addition, the birds need higher
                       Rather, their "habitat" has been the goal            elevation refuges during times of extreme
                       of several restoration and mitigation pro-           high sea levels.
                       jects. In addition, there is considerable
                       habitat value for migratory birds that rest              For Belding's Savannah sparrow
                       and feed in coastal wetlands (Onuf et al.            (Passerculus sandwichensis beldingi) the
                       1978, Onuf and Quarnmen 1985).                       mid-to-upper marsh provides territorial
                                                                            males with singing perches, females with
                          The need for strict assessment criteria           suitable nesting sites and materials,
                       follows from the fact that there is so little        proximity to food supplies, and distur-
                       information on how well constructed                  bance buffers.      Sparrows also need
                       wetlands carry out the functions of their            refuges during high sea level.
                       natural, southern California models.
                       Eleven functions of wetlands are consid-                 For salt marsh bird's beak
                       ered essential for restoration success               (Cordylanthus maritimus ssp. maritimus)
                       (from Zedler et al. 1988, 1990):                     the upper salt marsh provides a regenera-
                                                                            tion niche, (an annual supply of open
                                                                            space for germination of this annual,
                                                                            sensu Grubb 1977) and suitable host
                                                                            species for the seedlings to parasitize.


                                                                      6





                     Strategies for wetland constructiong restoration and enhancement


                     Adjacent upland habitats are needed to                ing microbial activities, and disrupting the
                     support pollinator insects.                           soil surface. Benthic molluscs, worms,
                                                                           and crustaceans consume foods produced
                         For wandering -skippers (Panoquina                in, and tidally transported through, the
                     errans, a rare butterfly), the salt marsh             marsh. Suspension feeders filter particles
                     provides dense patches of saltgrass                   from the water. Deposit feeders scrape
                     (Distichlis spicata), on which the larvae             the soil surface and deposit fecal pellets
                     are host specific.                                    and/or middens. Fishes and birds con-
                                                                           sume algae, detritus, and invertebrates, As
                         b. Support of food chains.                        well as frogs and other fishes.
                     While Pacific Coast wetlands probably
                     are less important to coastal fisheries than               c. Transformation of nutrients.
                     Atlantic Coast wetlands, shallow tidal                These activities include microbial and
                     creeks do provide nursery grounds for                 chemical processes controlling the
                     Pacific halibut (C. Onuf, US FWS, pers.               concentrations of nutrients and other
                     comm., S. Kramer, UCSD, pers.                         compounds and facilitating the biogeo-
                     comm.). Nordby (SDSU, pers. comm.,                    chemical cycling of nutrients and the flow
                     Zedler and Nordby 1986) believes the                  of energy. Microbes play an important
                     fishery values are primarily in providing             role in nutrient dynamics. Cyanobacteria
                     food for higher trophic levels, including             (blue-green algae) and soil bacteria fix
                     terns, herons, and other fishes (e.g.,                nitrogen; these supplies may be essential
                     halibut, diamond turbot). The endan-                  for plant growth during times of low
                     gered California least tern (Sterna                   nitrogen influx. Nitrification produces
                     antillarum browni) depends on shallow                 nitrates, which are available for plant
                     waters for food. Elsewhere in the nation,             uptake. Nitrates are also. substrates for
                     the nursery function that serves fish and             denitrification, and a high nitrification rate
                     shellfish populations is often the foremost           is central to rapid nitrogen cycling.
                     management goal. The support function                 Bacteria release nitrogen as gas (dehitrifi-
                     is perceived as follows:                              cation), thereby reducing con-centrations
                                                                           of this nutrient during times of excess
                         Marsh plants produce organic carbon,              influx or accumulation. Bacteria reduce
                     making it available to consumers and                  sulfates to sulfides (sulfate reduction)
                     decomposers. Epibenthic algae produce                 under anaerobic conditions; this may be
                     dissolved organic carbon (absorbed by                 followed by the precipitation of iron
                     invertebrate larvae) and highly digestible            sulfides. Sulfate reduction thus plays a
                     biomass (consumed by invertebrates and                significant role in organic matter
                     fishes). Macroalgae provide attachment                decomposition; these microbial reducers
                     sites for topsmelt (Atherinops affinis)               are available as food, and the reduced
                     eggs. Vascular plants produce organic                 sulfides store energy for other bacteria.
                     material for decomposers and herbivo-
                     rous insects; they also house many                        Nutrient transformations are not well
                     species of insects and spiders. Two                   known in Pacific coastal wetlands.
                     classes of decomposers modify the                     Because plant productivity of Atlantic
                     vascular plants; shredders break up dead              Coast and Gulf of Mexico salt marshes is
                     plant, material, facilitating leaching and            often nitrogen limited (Odum 1988), this
                     microbial growth, and microbial                       element has been the focus of most
                     organisms attack particles of litter                  assessments of nutrient dynamics.
                     (decomposition), making the detritus                  Recent studies suggest that nitrogen limits
                     more nutritious for higher consumers.                 plant growth and affects species interac-
                                                                           tions in southern California (Covin
                         The burrowing benthic animals (clam               1984). Nitrogen dynamics should thus
                     species, ghost shrimp, polychaetes,                   be considered in evaluating the function-
                     arrow gobies) mix the sediments                       ing of constructed marshes. At present,
                     (bioturbation), aerating the soil, enhanc-            little is known about nitrogen transforma-


                                                                      7





                     Strategies for wetland constructiong restoration an& enhancement


                     tions in southern California salt marshes.          plants to a specific date. Short-term
                     Although nitrogen fixers are present                objectives, such as a requiring only the
                     among the abundant algal mats and near              survival of transplants and not their
                     plant roots (rhizosphere), it isnot known           establishment, persistence, and spread,
                     if the fixed nitrogen is available to               allow -contractors to be freed of respon-
                     vascular plants. It is likely that processes        sibility, even when the intent of
                     such as nitrogen fixation and denitrifica-,         restoration is not fulfilled.
                     tion are limited by organic matter avail-
                     ability in the soil. If this hypothesis is              A functional criterion, such as requir-
                     true, then the presence of organic matter           ing self-maintaining populations, is
                     can determine the success of wetland                needed. Self-maintenance requires that
                     restoration or creation. The techniques             conditions favoring persistence, such as
                     for evaluating those processes are not              adequate nutrients.(and processes such as
                     simple and must be standardized. Thus,              nitrogen fixation) be present. Longer-
                     establishing methods for measuring                  term monitoring, and measurements of
                     nutrient transformation functions is an             vegetative expansion and seed produc-
                     important part of our current research              tion, should be employed.
                     program-
                                                                             Persistence of plant populations
                        Nutrient dynamics are strongly linked            develops through three mechanisms. The
                     to soil organic matter, which stores                marsh substrate maintains seed banks;
                     nutrients and provides organic substrates           these are especially important for short-
                     for bacteria involved in nitrogen fixation,         lived, non-rhizomatous species, e.g.,
                     denitrification, and the sulfur cycle. Salt         bird's beak, annual pickleweed
                     marsh vegetation tends to be nitrogen               (Salicornia bigelovii ), sea-blite (Suaeda
                     limited throughout coastal environments,            callfornica) allowing recovery from
                     including southern California (Covin and            mortality events. Perennial species may
                     Zedler 1988). Floods provide an influx              persist in part through longevity of
                     of nutrients, but this source is infrequent         individuals. The rhizornatous species
                     and undependable in our Mediterranean-              persist belowgound, even though indi-
                     type climate. It is unlikely that all of the        vidual stems may die each year.
                     nitrogen required of marsh vegetation can           Vegetatively reproducing species maintain
                     be supplied by tidal waters (Winfield               potential for expansion of clones.
                     1980). Hence, nitrogen fixation is
                     important for salt marsh plants, especially             e. Resilience. The region's high
                     for a region with hypersaline soils, where          environmental variability leads to the need
                     plants may require extra nitrogen to                for constructed wetlands. to be resilient,
                     regulate water uptake--some accumulate              i.e., able to recover following extreme
                     amino.acids. as osmolites. The potential            events, as well as human disturbances.
                     for nitrogen-fixation is higher where soil          Coastal wetlands are subjected to natural
                     organic matter content is high (Zalejko             hydrologic alterations, such as flooding
                     1989). The sulfur cycle is also affected            and closure to tidal action. Human
                     by low organic matter (Cantilli 1989).              impacts include street runoff, inflows of
                     Man-made wetlands are characteristically            fertilizers, pesticides and toxic wastes,
                     lower in soil organic matter (Lindau and            mechanical damage to vegetation,
                     Hossner 1981, Shisler and Charette                  increased sedimentation, -and encroach-
                     1984, Broome et al. 1986, Swift 1988,               ment by pets.
                     R. Langis et al. in press), so the nutrient
                     dynamics of artificial wetlands may limit               Alterations to a wetland's hydrologic
                     the development of vegetation.                      regime affects nearly every aspect of
                                                                         ecosystem structure and function. In
                        d.    Maintenance          of     plant          1984, Tijuana Estuary was closed to tidal
                     populations. "Successful restoration"               flushing for 8 months--a result of long-
                     is often judged by the survival of trans-           term human disturbances to the barrier


                                                                   8





                   Strategies for wetland construction, restoration and enhancement


                   dune and storm-induced overwashing in               dation. Organic soils that are wetted by
                   1983. The estuarine marsh became dry                seawater retain some buffering capacity;
                   and extremely hypersaline (Zedler and               they may prevent the development of acid
                   Nordby 1986). The clapper rail popula-              sulfate soils upon exposure of sulfide-
                   tion neared extinction as its food and              rich (H2S, FeS, FeS2) sediments. The
                   vegetative cover died out. After 5 years,           organic matter provides an energy source
                   recovery is not yet complete--the annual            for nitrogen fixers and decomposers.
                   pickleweed persisted only in a single, tiny
                   patch; cordgrass has not regained all of its            f.    Resistance       to      invasive
                   former distributional range; many of the            species (plant or animal). The continual
                   macroinvertebrates failed to recolonize;            threats of disturbance to topography and
                   the rail population has only half the num-          salinity lead to the need for constructed
                   ber of nesting pairs as in pre-closure              wetlands to resist invasive species (exotic
                   years.                                              to the region or alien to the habitat). Once
                                                                       established, many invasive species can
                       From this whole-system catastrophe,             persist.    A single season of altered
                   we learned that our remnant wetlands                hydrology may be enough to allow estab-
                   have limited resilience. Because regional           lishment and long-term presence of
                   biodiversity is already in jeopardy, it is          unwanted species. The cattail (Typha
                   essential that any artificial wetlands be           domingensis) is a local native of brackish
                   planned with that biogeographical consid-           marshes that invaded the San Diego River
                   eration in mind, Persistence of species,            salt marsh when the period of freshwater
                   and maintenance of the gene pool is a               inflow was artificially prolonged by.
                   regional function. The extremes that                reservoir discharges in 1980 (Zedler and
                   individual wetlands experience may                  Beare 1986). It was still present in 1990,
                   eliminate entire populations; for that              even though current salinities would not
                   system to recover, propagules must arrive           allow its establishment. Furthermore, a
                   from another. The presence of species in            moderate increase in freshwater inflow at
                   nearby wetlands should speed recovery               this time could stimulate vegetative
                   by increasing the availability of                   expansion now that the species is present
                   propagules. Such refuges, are especially            in the marsh.
                   important for plant species that do not
                   develop persistent seed banks (e.g.,                    The hydrologic regime (salinities and
                   Salicornia bigelovii).                              soil moisture regimes) usually precludes
                                                                       establishment of species foreign to the
                       In order for the fish and benthic               salt marsh, such as cattails (Typha
                   macroinvertebrate communities of a con-             latifolia) and bulrushes (Scirpus spp.).
                   structed wetland to be resilient, there             The mature marsh sod and vegetation
                   must be access to larvae; thus the site             canopy function. to reduce seedling sur-
                   must have hydrologic connections with               vival of exotic plants such as rabbit-foot
                   other systems in the area. For the insect           grass (Polypogon monspeliensis) and
                   community to be resilient, constructed              brass buttons (Cotula coronopifolia).
                   marshes should not be too isolated. In a            Constructed salt marshes may lack suffi-
                   region where extreme and sometimes                  cient vegetative cover to prevent inva-
                   catastrophic events can't be avoided, it is         sions. If wetlands are constructed in
                   essential that the wetlands retain connec-          urban areas, freshwater inflows may be
                   tions with other systems to aid recovery            augmented by street runoff, and soil
                   of sensitive populations.                           salinity regimes may favor germination
                                                                       and seedling establishment of brackish
                       The accumulation of organic matter in           marsh species. If the hydrologic regime
                   soils also plays an important role in con-          cannot be corrected, weed control mea-
                   ferring resilience. Organic soils retain            sures must be planned and implemented
                   moisture that may help plants survive               as aliens appear. Most invaders will be
                   periods of infrequent or brief tidal inun-


                                                                  9





                       Strategies for wetland construction, restoration and enhancement


                       easiest to manage if individuals are hand
                       pulled early in the invasion process.                   When the functions that confer
                                                                           resistence to outbreaks are lacking and
                          Exotic animals are also of concern.              herbivores get out of control, the vegeta-
                       Mosquitofish (Gambusia affinis) and                 tion is negatively affected. A cordgrass
                       sailfin molly (Poecilia latipinna) have             (Spartina foliosa) planting on a dredge
                       been recorded from coastal wetlands in              spoil island in San Diego Bay looked like
                       the San Diego area. The yellowfin goby              a "successful" marsh for the first three
                       (Acanthogobiusflavimanus) is a current              years; then, a population of scale insects
                       threat that appears to be moving south              (Haliaspis spartina) irrupted and.nearly
                       along the California coast with extreme             decimated the vegetation.             Kathy
                       rapidity. A benthic, mussel from Japan              Williams (SDSU, pers. comm.) attributes
                       (Musculus senhousia) has invaded                    the outbreak to a lack of predators. In
                       subtidal habitats of both Mission Bay and           natural marshes a coccinelid beetle
                       San Diego Bay, where it seems to                    (Coleomegilla fuscilabris) appears to
                       displace native bivalves (D. Dexter,                control outbreaks --under experimental
                       SDSU, pers. comm.). In studies along                conditions, it feeds voraciously on scales.
                       San Diego Bay, comparing a constructed              Neither parasites nor predators were
                       wetland with a natural marsh remnant, S.            deliberately introduced to the marsh, and
                       Rutherford trapped many individuals of              they did not become established on their
                       the exotic mussel in the artificial marsh,          own. This was our first experience with
                       but found only one in the natural system.           an insect outbreak, and no one anticipated
                       Once established, such exotics may                  it. We learned that resistance to defoliat-
                       preclude development of the native fauna.           ing herbivores is an important function of
                                                                           natural marshes. Because it may take
                          We do not know what defense                      pest species several years to cause notice-
                       mechanisms natural wetlands may have to             able mortality or defoliation, the success
                       prevent or slow invasions of exotic                 of a marsh construction project cannot be
                       species. Where native species are already           determined without long-term study.
                       abundant, there may be insufficient food
                       or space for invaders. The salinity                    h. Pollination. While many salt
                       regime may prevent survival or settling of          marsh plants lack showy flowers and are
                       larvae that are alien to the salt marsh,            wind pollinated, a few species rely on
                       such as mosquitofish.           A dense             insects. The annual salt marsh bird's
                       community of benthic organisms may                  beak (Cordylanthus maritimus ssp.
                       filter exotic larvae from the water column.         maritimus) is pollinated by bees and flies,
                                                                           on which this endangered species relies
                          g.   Resistance to herbivore                     for successful seed set. For such insects
                       outbreaks. In native wetlands, insect               to be present, their nesting habitat must
                       herbivores are diverse and abundant, but            be also be available nearby--for the 5
                       population outbreaks are uncommon.                  species that potentially pollinate bird's
                       Native predators, including birds, carniv-          beak (Lincoln 1985), salt flats and higher
                       orous insects, and parasitic wasps, keep            ground with mammal burrows are the
                       herbivore populations in check. Where               likely nesting sites.
                       such predators are lacking, herbivore
                       populations may go out of control.                     Brian Fink successfully transplanted
                       Herbivores also respond to the nutrient             the bird's beak to a restored higher marsh
                       status of plants. Where nutrient-rich               area at Sweetwater Marsh in 1990;
                       wastewaters flow into coastal wetlands,             however, flowers did not produce seeds.
                       the nitrogen status of the salt marsh plants        He attributed the population failure to lack
                       improves, and insect grazer populations             of habitat for the pollinators (Fink,
                       may expand before predators are able to             SDSU, pers. comm.).
                       crop the increased prey base..



                                                                    10





                     Strategies -for wetland construction, restoration and enhancement


                                                                         then the entire intertidal marsh will be
                        L Maintenance of local gene                      flooded with two feet of water or more.
                     pools. A species may be maintained                  Where a habitat refuge is lacking,
                     through transplantation or other means of           survival through extreme events is
                     artificial propagation, but its genetic             uncertain. While the refuge function of
                     integrity may be modified in the process.           buffers needs further quantification, it is
                     Nearly every author for EPA's regional              clear that buffers are necessary during
                     restoration reviews (Kusler and Kentula             storm periods and for future intertidal
                     1989) expressed concern that local gene             habitat as sea level rises.
                     pools be maintained in nature.
                                                                            k. Accommodation of rising
                        The gene pool is threatened in at least          sea level. Park et al. (1989) estimate
                     two ways--when local genetic diversity is           that a one-meter rise in sea level would
                     not salvaged and when alien material is             eliminate 65% of the coastal marshes and
                     brought in from other regions. In the               swamps of the contiguous US, because
                     first case, the failure to retain a broad           the upward migration of wetland ecosys-
                     representation of local plants or animals           tems is restricted by coastal development.
                     may result in a wetland with low genetic            Such a rise is probable by the year 2100.
                     diversity, with reduced material for                In southern California, even a half meter
                     natural selection. In the second case,              rise, would wipe out closer to 100% of
                     local gene pools may be reduced through             the remaining wetlands, because the
                     competitive exclusion that would not                upland transitional habitats needed to
                     normally occur.                                     support the rising marshlands are all
                                                                         developed. We're probably stuck with
                        Genetic integrity is not only important          rising sea level, so restoration planning
                     for its own sake. Long-term maintenance             should accommodate it. Instead of grad-
                     of the habitat may be at risk. A plan to            ing an entire site to intertidal elevations,
                     .transplant cordgrass from San Francisco            transitional habitats should be left, and
                     Bay to San Diego Bay, 500 miles to the              connections to upland topography should
                     south, was criticized by PERL biologists            be maintained. As Bill Niering of
                     who argued that the northern populations            Connecticut College wrote (in Kusler and
                     might be less tolerant of high tempera-             Kentula 1989), "Our basic goal is to
                     tures and hypersalinity. An extreme                 create a persistent functional wetland
                     event could wipe out the imported                   system. In some situations this may be
                     material, perhaps years after establish-            more important than the creation of a
                     ment. A local source of cordgrass that              specific wetland type since the present
                     was destined for destruction was                    physiognomy may merely be a
                     identified and used instead.                        momentary expression of the system's
                                                                         vegetation potential in the future."
                        j.    Access to refuges during
                     high water. California's Coastal Act
                     requires a 100-foot buffer around wet-
                     lands to reduce disturbances to the
                     protected ecosystem, although some have
                     considered bike trails and parking lots
                     compatible uses within the buffer zone.
                     The importance of having a functional
                     refuge is evident during extreme high
                     waters, when clapper rails and other
                     animals need to escape their flooded
                     habitat. Storms can raise water levels
                     well above predicted tidal heights, and if
                     storms coincide with the highest spring
                     tides of the year (as in January 1988),





                      Strategies for wetland construction, restoration and enhancement


                                                                           cattails), and resident natives that undergo
                                                                           population irruptions not seen in natural
                                 4. Criteria for                           wetlands (e.g., scale insects on
                           "successful mitigation"                         cordgrass). Annual surveillance will be
                                                                           needed for problem species, so that
                      as required in.San Diego Bay                         corrective measures can be initiated early
                                                                           enough to be effective.

                          How similar should the functions of                  Finally, we recommend that an
                      constructed and natural wetlands be                  objective scientific panel review the
                      before the project is considered                     sampling or monitoring program used to
                      successful mitigation? In order to insure            judge compliance/success.          For the
                      no net loss of habitat values, it is                 Caltrans Connector Marsh, the US Fish
                      necessary to have high expectations for              and Wildlife Service anticipated the need
                      wetlands constructed or modified for the             for interim reviews of the mitigation
                      purpose of mitigating losses elsewhere.              program. The federal agencies and
                      In the past, standards have varied from              contractors must meet with the Service
                      project to project. Where standards are              annually to review project status and
                      lax, there is greater risk that efforts to           recommend any remedial actions (US
                      retain or improve upon wetland values                FWS 1988, p. 23).
                      will also be inadequate.
                                                                               In a recent decision, the US Fish and
                          High standards are necessary if                  Wildlife Service prescribed detailed
                      projects are to comply with agency                   objectives, including functional attributes,
                      policies, and detailed criteria for                  for evaluating the success of the
                      assessing success are needed to document             mitigation project at the Connector
                      in detail what is happening on the                   Marsh, constructed by Caltrans in Chula
                      restoration site. In addition, scientific            Vista. Three endangered species occur in
                      studies should be included to identify               the affected area, the light-footed clapper
                      what causal factors are responsible. If,             rail, the California least tern, and the salt
                      for example, nutrient concentrations are             marsh bird's beak. When the Sierra Club
                      unusually low, an understanding of the               charged the federal agencies with failure
                      reasons will help in identifying corrective          to enforce the original mitigation
                      measures and in preventing similar                   requirements (primarily a transfer of land
                      problems in the future (Broome et al.                from private to public ownership,
                      1987).                                               subsequently ordered by the court;
                                                                           Thompson 1988), it became possible to
                          Obviously, for a wetland designed to             revise and update the "Section 7
                      provide habitat for use by endangered                Consultation" under the Endangered
                      birds, judgments of success should                   Species Act, strengthening the require-
                      include the presence of those populations            ments both for mitigation and for judging
                      and perhaps their self- maintenance.                 its success.
                      Annual censusing of rare and endangered
                      birds is needed plus 5- and 10-year                     The new requirements are set forth in
                      follow-up studies of the plant and animal            the "Biological Opinion" (US FWS 1988)
                      communities and ecosystem functions                  for the Combined Sweetwater Flood
                      that develop on site.                                Control and Freeway Project.            "The
                                                                           Service shall deem that the wetland
                          Special attention should be paid to              creation and modification projects are
                      problem species. At least three categories           successful on showing that the channels
                      have been identified in constructed                  and emergent wetlands provide suitable,
                      wetlands: invasive exotics (e.g., rabbit-            functional habitats for the California least
                      foot grass), invasive natives that are alien         tem and light-footed clapper rail, and the
                      to the desired wetland community (e.g.,              emergent wetlands are also vegetated by


                                                                    12





                        Strategies for wetland construction, restoration and enhancement


                        patches of salt marsh bird's beak and 75
                        percent of the native species currently               5. Reference wetlands and
                        occurring in the Sweetwater River                           reference data sets
                        Wetlands Complex." (ibid., p. 23) The
                        Service went beyond this general goal                   In order to compare constructed wet-
                        and provided specific criteria as follows:          lands with natural ecosystems, there must
                            Channels need to provide "suitable              be data on the structure and functioning
                        habitat for the California least tem and the        of representative natural wetlands.
                        light-footed clapper rail." Forage items            Because most southern California wet-
                                                                            lands have been disturbed, there are no
                        need to be present for 2 years at levels of         pristine wetland examples. Even in
                        75 percent of the density and diversity of          nearby Baja California, where coastal
                        the prey base in comparable habitats with           development is less extensive, there are
                        the Sweetwater River Wetlands Complex               few examples of undisturbed habitat.
                        (SRWC). Wetland habitat for rails must              Selection of wetlands to serve as models
                        include 7 home ranges for 2 years, each             for restoration must therefore be based on
                        with non-overlapping areas of 2-4 acres,            an understanding of how disturbance
                        including low, middle, and high marsh.              affects wetland ecosystems. Two addi-
                        Lower marsh in each home range must                 tional features of Southern California
                        have at least I patch of cordgrass of 60-           wetlands make it difficult to characterize
                        80 cm height and 90-100% cover that is              the reference wetland or restoration tar-
                        go-100 m2 in size and able to maintain              get. The first is spatial heterogeneity
                        itself (i.e., in place for 3 yr and with N-         within and between wetlands; the second
                        fixation). The middle marsh must have               is interannual variability, due to both
                        >70% cover with 75% of the typical                  natural and man-caused events.
                        native species at SRWC. The high marsh
                        must have <20% cover of weedy species                  The problem of spatial vari-
                        and maintain 5 separate patches (of I m2            ability. No two wetlands are identical in
                        and at least 10 m part, with >20                    species lists, distributions, or rates of
                        plants/patch) of bird's beak that are self-         various processes. Yet the spatial vari-
                        sustaining (stable or increasing in number          ability among the region's wetlands is
                        and area) for 3 yr. An attempt should be            more of an aid than a hindrance in under-
                        made to include high saltmarsh berms                standing cause-effect relationships.
                        near areas of low saltmarsh.                        Current knowledge of wetland structure
                           These new requirements represent a               and function comes from long-term
                                                                            experience and study in several wetlands,
                        major advance in agency expectations for            with each site contributing unique
                        successful mitigation. Their effectiveness          information.
                        in insuring the replacement of in-kind
                        habitat will be evaluated along with the               Four main study sites have con-
                        constructed habitat.                                tributed to our understanding, with the
                                                                            longest period of record at Tijuana
                                                                            Estuary (Table 11. 1). The results of these
                                                                            studies indicate that no one wetland can
                                                                            serve as a reference site for any man-
                                                                            made habitat. Information from con-
                                                                            structed wetlands needs to be compared
                                                                            with the total available information,
                                                                            preferably by a panel of scientists familiar
                                                                            with the study sites, to insure thorough,
                                                                            objective evaluation. Such a process has
                                                                            been initiated by Caltrans, involving
                                                                            scientists from the Pacific Estuarine



                                                                      13





                 Strategies for wetland construction, restoration and enhancement


                 Research Laboratory and resource agency             maps of habitat types in southern
                 staff to help assess wetland functions at           California coastal wetlands, based on
                 the Connector Marsh.                                1985 aerial photography. However, their
                                                                     habitat classifications have not been
                     The problem of temporal vari-                   checked in the field. Sharon Lockhart
                 ability. It has taken several years to              used the FWS draft maps to estimate the
                 understand just a few of the functions of           areas of 23 coastal wetlands in San Diego
                 the Tijuana Estuary salt marsh, largely             County. She outlined each of the poly-
                 because of the high interannual variability         gons with a planimeter to obtain areas,
                 and the importance of extreme events in             and summarized the acreage of each
                 triggering changes in the vegetation. Ten           habitat type and each wedand. Acreages
                 years of data on plant distributions and            included areas between the ocean inlet
                 abundances are still inadequate, because            and the first major break in habitat toward
                 we have not witnessed all types of                  the east. Freeway 5 was the limit for
                 extreme events or human impacts. Our                wetlands in San Diego and Mission Bays;
                 knowledge of vegetation control func-               El Camino Real was the limit for Los
                 tions includes relationships with salinity-         Peflasquitos Lagoon north to Buena Vista
                 inundation regimes, but is weak concern-            Lagoon. The FWS habitat classifications
                 ing interactions with nutrients, soil redox         were combined into 5 habitat types: bay,
                 conditions, heavy metals and other toxic            channel, salt marsh, brackish/fresh
                 materials. Yet this is the best data set            marsh, impounded waters, and other
                 available, and it serves to caution man-            habitats (riverine and unidentified poly-
                 agers that high interannual variability may         gons).
                 be the rule, rather than the exception, for
                 the region's wetlands.                                  Excluding the 5,420 ha of subtidal or
                                                                     bay habitat, this survey indicates 756 ha
                     It is thus apparent that short-term             of salt marsh, 832 ha of brackish and
                 assessments must document trends,                   fresh marsh, 495 ha of impounded
                 rather than "average states." Monitoring            wetlands, 163 ha of channels; and 32 ha
                 programs must take more than                        of other wedand habitat types in San
                 "snapshots" of the system under study;              Diego County (Figure 11. 1). However, it
                 time series are needed to determine the             is likely that these are underestimates
                 direction of developments. Rather than              because many wedand areas may not be
                 focusing on one-time measures of trans-             distinct on aerial photos. Comparative,
                 plant survival (often the only requirement          field based data for wetlands at Tijuana
                 for monitoring mitigation sites), it is more        Estuary were obtained in a PERL survey,
                 important to assess the ability of the sys-         which included extensive field sampling
                 tem to respond to changing environments             over large areas of disturbed wetland.
                 (e.g., expansion following winter stream-           The map by PERL ecologists indicated
                 flow and low soil salinities) and the               much larger areas of wedand at Tijuana
                 likelihood that populations can be main-            Estuary than the FWS map (556.3 ha
                 tained through environmental extremes               compared to 284.1 ha). For Tijuana
                 (e.g., measures of seed production; size            Estuary, the FWS draft inventory
                 of seed bank), to identify any major shifts         appeared to be a 50% underestimate of
                 in the community (e.g., loss of desired             wedand area.
                 plant species), and to develop corrective
                 measures for problems that are seen                    For Tijuana Estuary, the areas of
                 (e.g., eradication of exotic invaders               habitat from more detailed mapping,
                 before they become widespread).                     including ground truthing, are given in
                                                                     Figure 11.2. The areas were obtained
                    The region's wetiand resources                   using the SDSU Geographic Information
                 have not been censused in detail. The US            System.
                 Fish and Wildlife Service (National
                 Wetlands Inventory) has prepared draft


                                                               14






                     Strategies for wetland construction, restoration and enhancement


                     Table H.1. A list of sites and types of data currently gathered by scientists associated with
                     the Pacific Estuarine Research Laboratory. While there are additional data for these and other
                     sites, only sampling programs that use comparable methods are listed. TE = Tijuana Estuary;
                     SDR = San Diego River Marsh; LPL = Los Penasquitos Lagoon; CM = Connector Marsh and
                     PC = Paradise Creek, both on San Diego Bay. Similar vegetation and salinity data have been
                     obtained at Estero de Punta Banda, Baja California, by Silvia Ibarra-Obando at CICESE,
                     Ensenada, B.C.

                     Location:                          TE           SDR          LPL         CCM           P

                     Soil salinity data                 X            X            X           X             X

                     Streamflow data (USGS)             X            X            X

                     Lower salt marsh veg. data         Sept.        July         Sept.       summer        summer
                      Number of stations                102          250          86          64            7
                      Number of years                   10           6            2           3             3
                      Nutrient dynamics data                                                  qtrly         qtrly
                      Number of years                                             5           3             3

                     Upper salt marsh data              Sept.                     Sept.
                      Number of stations                115                       12
                      Number of years                   4                         5

                     Fish and invertebrate data         qtrly                     qtrly
                      Number of stations                4-6                       3
                      Number of years                   4                         5


                     Figure H.1. Comparison of habitat areas in 23 wetlands of San Diego County. Areas
                     exclude subtidal bay habitats.


                            500-


                            400-


                            300-
                      ca

                            200-

                      3:


                               0-                                                      1   F       I  I     I I   I   I   I

                                  COCO :30COOO WW2>'-O
                                                            0     A2,  0   -0 -   0    0
                                       0
                                  0                   a                       Mn  2    cc
                                  LLI  CD     (z  6   .0    :1M   LU   .5  .2 >                                       0    0
                                              CQ  r   Cn    0- 0)                      M   (D C$)           0 -0           a)
                                              0   CV  .!2   'V                             -0         Z-)   M  a) :3
                                                                              c               (V   CD
                                                                                                                      0
                                                                  Cn   W   X: 0                                E (L
                                  0    0      E   cn        tc         Im     :3
                                                                              M                                       0
                                              CO            (D0            as          CO  (V      ,  2
                                       cn     LL            (L CI)         :3                 as   0 LL
                                          CO                                      E    05                                  Cid
                                                                                                              D           CO
                                                                                  0                                   W
                                                                                           0                          C/)








                                                                     15






                  Strategies for wetland construction, restoration and enhancement


                  Table 11.2. San Diego County wetland habitats, deterrnined from US FWS draft maps of
                  the National Wetland Inventory by S. Lockhart. Data are hectares (1 ha = 2.471 ac). Br/Fr
                    Brackish/Freshwater.
                                                                     Saline     Br/Fr   Impounded
                  Location                    Bay       Channel      Marsh      Marsh      Waters        Other

                  Tijuana Estuary              0.0       223.6       171.1      88.1         0.0         1.4
                  San Diego Bay             4483.2           .2      11.0       23.3       430.9         0.0
                  Sweetwater                   0.0         1.9       116.1      18.6         0.0         1.0
                  Famosa Slough                0.0         2.6        1.5        0.0         0.0         0.0
                  San Diego River             62.6         0.0       47.1       19.8         0.0         1.1
                  Mission Bay                620.1         0.0       35.3       39.9         0.0         0.0
                  Los Pefiasquitos             0.0         3.1       130.7      50.0         0.0         0.0
                  San Dieguito                30.0         0.0       28.7       36.7         0.0         0.8
                  San Elijo                    0.0        31.6       87.6       74.2         0.0         0.0
                  Batiquitos                  42.7        99.9        8.6       52.7         0.0         0.0
                  Aqua Hedionda               105.9        0.1       31.4       26.9         0.0         0.0
                  Buena Vista                  0.0         0.0        0.0       15.6         64.6        0.0
                  Lorna Alta                   0.0         0.0        0.0        0.7         0.0         0.0
                  San Luis Rey                 0.0         0.7        0.0       82.6         0.0         2.0
                  Oceanside Harbor            85.3         0.0        0.2        0.0         0.0         0.0
                  Santa Margarita             30.4         0.0       87.3       79.0         0.0         0.0
                  Cockleburr Cyn               0.0         0.0        0.0        2.0         0.0         0.0
                  French Canyon                0.0         0.0        0.0        6.3         0.0         0.0
                  Aliso Creek                  0.0         0.0        0.0       10.2         0.0         0.0
                  Unnamed Canyon               0.0         0.0        0.0        3.8         0.0         0.0
                  Las Pulgas Cyn               0.0         0.0        0.0       46.8         0.0         0.6
                  San Onofre Creek             0.0         0.0        0.0        8.8         0.0         0.0
                  San Mateo Creek              0.0         0.0        0.0       56.3         0.0        32.2





                  Figure 11.2. Area of several wetland habitat types at Tijuana Estuary, as determined by
                         PERL from detailed ground truthing of the 1986 aerial photo.


                    Other wetlands
                   Brackish/Fresh A
                    Riparian scrub -
                         Transition
                              Mudflat
                         Salt panne-.
                         Salt marsh -
                             Channels
                                Beach
                                       0                      100                     2@O

                                                                     Hectares


                                                              16






                    Strategies for wetland construction, restoration and enhancement


                                                                         Two major questions will be answered,
                          6. How should major                            in sequence, using replicate experimental
                        restoration programs be                          marshes: First, how will different
                                                                         degrees of tidal influence affect pickle-
                                 undertaken?                             weed marsh? Second, how important is
                                                                         topographic complexity to wedand func-
                        It is recommended that major restora-            tioning--should small tidal creeks be
                    tion projects, especially those involving            excavated within the marsh plain to pro-
                    techniques or habitat types for which                vide habitat for a diverse macrobenthos
                    there are no previous examples, begin                and food chain?
                    with an experiment to test methods of
                    restoration on the site. A small effort in               To answer the first question, 24 small
                    planting vegetation or modifying the                 tidal marshes (lxlO-m mesocosms;
                    topography in various configurations,                Figure 11.3) will be constructed adjacent
                    followed by evaluation over a growing                to an existing tidal channel. Each will be
                    season, will help rule out techniques that           assigned to one of 6 treatments (4x repli-
                    don't work in the short-term and will help           cation). Soil and vegetation attributes
                    identify promising approaches that can be            (including both vascular plant and algal
                    developed further                                    producers) will be followed through one
                                                                         growing season. Study of the ecosystem
                        All projects should be continually               responses will determine the degree of
                    evaluated with a long-term functional                tidal flushing and freshwater inflow
                    assessment program.          An adaptive             needed to manage the existing pickleweed
                    management approach will improve the                 ecosystem and to construct new pickle-
                    restoration program through time; that is,           weed marshes.
                    collection of information about system
                    development, identification of problems,                 To answer the second question, a 20-
                    and experimentation with new restoration             acre area adjacent to an estuarine channel
                    techniques, will provide the information             will be graded down to approximately 4.5
                    necessary to incorporate corrective                  ft MLLW for development as an
                    measures.                                            experimental intertidal marsh. Replicate
                                                                         subareas (n=3) will be constructed with
                       The Tijuana Estuary Tidal Restoration             and without tidal creeks. Results from
                    Program provides a good example. A                   this experiment (vegetation and soil
                    plan to restore full tidal flushing to about         development, invertebrate colonization,
                    200 ha (500 ac) of the estuary was devel-            and bird use) will guide implementation
                    oped by two hydrologists, Phil Williams              of later phases of the project. Since
                    and Mitch Swanson (1987). Review of                  funds have not been identified for the
                    the initial, "minimum dredging plan" by              larger restoration program, it is likely that
                    PERL biologists indicated that some areas            several years of data will be available by
                    where dredging was proposed were criti-              the time results are needed. Meanwhile,
                    cal habitat for sensitive species.                   information will add to the technical
                    Alternative sites for new channels and               information base and guide restoration
                    intertidal marsh habitats were then                  projects elsewhere.
                    sought, and a compromise was developed
                    to reduce biological impacts but require a
                    more costly dredging program. The
                    revised plans will soon be available as an
                    Environmental Impact Report/Statement
                    (EIR/EIS for Tidal Restoration of Tijuana
                    Estuary, prepared for the California State
                    Coastal Conservancy). The EIR/EIS
                    proposes a low-cost experimental phase
                    to precede major dredging and grading.

                                                                  ,17





                  Strategies for wetland construction, restoration and enhancement




                   Figure 11.3.
                                                              -2
                   Map of 24 tidal mesocosms; at         P":                  '.'0'
                                                                 A_A_A_ 3      ;'
                                                                               %
                   Tijuana Estuary. Each of the
                   experimental blocks (1-4) includes
                   6 hydrologic treatments:                                 4
                                                              i;. isle
                                                                      wt i
                   3 tidal flushing regimes, each
                   with and without freshwater inflow.


                   Reduced tidal flushing     Full tidal flushing     Prolonged flooding



                                                        6
                                              P-1. ' WIT M.... C            ...... S, rIki i
                      Tidal influence restricted Daily tidal inundation Daily tidal inflow,
                      by one-way flap gate that and drainage          drainage impeded by
                      reduces inflow, but allows                      height of outlet
                      drainage



                            View of tidal mesocosm construction plan



                        Tide
                        gate                                                  7.3 ft MLLW

                                                                              5.3 ft MLLW
                                         I Orn (33ft)                 lp_@, rn (3.3ft)

                            Interval view after planting              Saficornia virginica
                       Tide
                       qate


                                                                 U
                                                           f'r








                                                   18





                                                   Assessment Case Study


                                                                         College Program, Department of Com-
                           111. Case Study:                              merce, under grant number NA85AA-D-
                                                                         SG140, project number R/CZ-82,
                          Sweetwater River                               through the California Sea Grant College
                         Wetlands Complex                                program, with matching funds from the
                                                                         California State Resources Agency.

                                                                             Free sulfide in natural and
                                                                         constructed salt marshes (from
                         Our research site is within the largest         Cantilli et al. 1989 and Cantilli 1989).
                     and most controversial (Thompson 1988)              The presence of only trace amounts of
                     mitigation project on San Diego Bay.                free sulfide in a man-made marsh on San
                     The project combines highway widening,              Diego Bay suggests that its biogeo-
                     construction of a new freeway inter-                chemical functioning is not equivalent to
                     change, and excavation of a flood control           that of a natural salt marsh.
                     channel. Mitigation for lost wetland habi-
                     tat is being carried out by the California              Sediments in the artificial system and
                     Department of Transportation (Caltrans)             an adjacent natural marsh were sampled
                     and includes construction and enhance-              near the seaward edge of cordgrass
                     ment of intertidal salt marsh habitat (cf.          (Spartina foliosa) growth. Concentra-
                     US ACE 1982, Swift 1988) within the                 tions of free sulfide (112S, HS) in the
                     City of Chula Vista (32L'10'N, 117L'                natural marsh were significantly greater
                     10'W). The mitigation marshes include               than in the constructed marsh (Figure
                     the "Connector Marsh," which was                    Ell. 1), with levels up to 3 mM/L at 25-cm
                     constructed as a hydrologic link between            depth. Further, data on cordgrass aerial
                     Paradise Creek and the Sweetwater                   biomass from marshes at San Diego Bay
                     Marsh, and Marisma de Naci6n, a 17-                 and Tijuana Estuary suggest that free
                     acre marsh excavated from the "D Street             sulfide is not directly phytotoxic. Sulfide
                     fill" in early 1990. The marsh, channel,            is a product of sulfate reduction, a
                     and creek habitats are within the range of          process that typically dominates anaerobic
                     three birds that are on the federal                 decomposition and carbon cycling in salt
                     endangered species list: the light-footed           marshes. This process may be limited by
                     clapper rail (Rallus longirostris levipes),         low sedimentary organic matter content in
                     the California brown pelican (Pelecanus             the man-made marsh (Table 111. 1). The
                     occidentalis), and the California least tern        near-absence of sulfate reduction in the
                     (Sterna antillarum browni) and one                  artificial marsh may affect energy flow
                     endangered plant, the salt marsh bird's             and export, as well as the retention of
                     beak (Cordylanthus maritimus ssp.                   heavy metals and anthropogenic sulfur.
                     maritimus). Mitigation marshes at this
                     site must provide functional habitat for
                     the rail, the tern, and the bird's beak (US
                     FWS 1988).                                          Table 111.1. Means of percent organic
                                                                         carbon in marsh soils at depths of 0-5 cm.
                         While the assessment study is not yet           and 5-10 cm. Values were obtained by
                     complete, results are available for soils,          weight loss (dry wt) on ignition at 7000 C
                     nutrients, vegetation, and epibenthic               for one hour.
                     invertebrates (Langis et al. in press;
                     Zedler and Langis in press). Compari-               Dgpth                  Natural      Artificial
                     sons of fishes, channel benthos, and
                     birds are in progress.                              0-5 cm                 8.14          4.33
                         The work has been sponsored by                  5-10 cm                9.24          3.98
                     Caltrans and NOAA, National Sea Grant



                                                                   19






                                                      Assessment Case Study


                       Figure HI.I. Pore water concentrations of fi-ee sulfides in the artificial (A) and natural
                       (N) marshes at depths of 5, 15, and 25 cm. Bar        I s.e.



                                        0.7-


                                        0.6-


                                        0.5-

                                  E     0.4-
                                  a)
                                  _0
                                        0.3-

                                  U)
                                        0.2-


                                        0.1-


                                        0.0-
                                               A-5 A-15 A-25 N-5 N-15 N-25

                                                                  Site and Depth



                                                                          higher-- generally twice as high--in the
                          Potential nitrogen inputs (N-                   natural marsh than in the man-made
                       fixation) in natural and man-made salt             marsh for five of six sampling periods
                       marshes (modified from Zalejko et al.              (Table 111.2, Figure 111.2). In September
                       1989, and Langis et al. in press). Data            1988, there was. no difference between
                       indicate that nitrogen fixation provided           the marshes. The rates of nitrogen in the
                       more nitrogen in the natural salt marsh            natural marsh, although greater than in
                       (Paradise Creek Marsh) than in the man-            the constructed marsh, were still very low
                       made (Connector Marsh) salt marsh                  by comparison with Atlantic Coast wet-
                       located at San Diego Bay.                          lands. While nitrogen-fixation at this one
                                                                          natural marsh may not be representative
                          Using the acetylene reduction tech-             of the region, the indication is that nitro-
                       nique, potential N-fixation rates were             gen limits the growth of cordgrass. N-
                       measured in both the root zone of cord-            fixation is one mechanism by which
                       grass (Spartina foliosa) and on the sedi-          nitrogen can be supplied continuously
                       ment surface in association with blue-             without the herbivore-stimulating effects
                       green algae. Nitrogen fixation was mea-            that sometimes accompanies fertilizer
                       sured at the same intertidal elevation in          treatments. Lower N-fixation rates in the
                       both marshes to eliminate differences due          constructed marsh were related to lower
                       to soil moisture. Rates of N-fixation on           soil organic matter levels (see next page).
                       the sediment surface were significantly



                                                                    20






                                                Assessment Case Study

                                                                    nitrogen fixation. At this study site, the
                      Rates of N-fixation in the root zone of       natural marsh was 2.3 times higher in
                  cordgrass were often similar for the con-         above-ground plant biomass (Langis and
                  structed and natural marshes (Table               Zedler in press). Other studies (e.g.,
                  111.3). Rates were significantly higher in        Covin 1984) have shown that nitrogen is
                  the natural marsh for only two out of five        limiting to salt marsh plant growth. N-
                  sampling times. Langis et al. (in press)          fixation is thus a very important process
                  attribute the high rates in the constructed       because it introduces new nitrogen into
                  marsh to the low nitrogen concentrations          salt marsh ecosystems.          A positive
                  found there. Nitrogen fixation is known           feedback control system is suggested--as
                  to shut down when nitrogen is abundant            cordgrass begins growth, organic matter
                  in the environment.                               becomes available to N-fixers in the
                                                                    rhizosphere, and N-fixation is stimulated.
                     Significant positive correlations were         Increased nitrogen levels then stimulate
                  found between N-fixation rates and per-           more rapid growth of cordgrass. On the
                  cent organic matter and belowground               soil surface, similar interactions with
                  biomass (Figure 111.3) showing the                microalgae may be present.
                  importance of primary producers for



                  Table 1H.2. Rates of N-fixation in surface cores (1 cm deep) for several constructed and
                  natural marsh sites, expressed as nmol C2H2/hr/m2. Data are means (and s.e.) for 5-12
                  samples from the Connector and Paradise Creek marshes adjacent to San Diego Bay. Data
                  are from Langis et al. (in press).

                                                           Constructed Marshes                   Natural
                                     Date              Islands           North Bank               Marsh

                                 Feb. 1988            15.0 (4.62)           7.3 (4@62)       33.0   (4.30)
                                 Apr. 1988            42.6 (22.74)       15.6  (6.35)       118.9   (32.28)
                                 July 1988            45.4 (2.16)        47.6  (4.94)        70.2   (9.87)
                                 Sept. 1988           34.7 (0.99)        46.5  (7.61)        34.0   (1.15)
                                 Feb. 1989            24.5 (2,1)         26.8  (2.68)        61.5   (8.70)
                                 Mar. 1989              no data          19.5  (0.88)        24.7   (1.49)





                  Table 111.3. Rates of N-fixation within the cordgrass rhizosphere (10 cm deep) for con-
                  structed and natural marshes. Data are nmol C2H2ft/m2 as in Table 111.2.

                                                           Constructed Marshes                  Natural
                                    Date               Islands           North Bank               Marsh

                                 Dec. 1987             no data             3.0   (0.51)        7.5  (0.82)
                                 Feb. 1988          105.5 (30.63)        44.3 (16.00)      104.3 (51.31)
                                 Sept. 1988           34.7 (0.99)        46.5    (7.61)      34.0    (1.15)
                                 Apr. 1988            96.2 (20.56)       77.0  (17.60)      161.9   (30.78)
                                 Sept. 1988         251.7 (20.78)       251.8  (40.56)       73.7   (9.54)




                                                              21






                                                    Assessment Case Study



                      Figure 111.2. Mean N-fixation
                      (acetylene reduction) on the                         120-
                      sediment surface at individual sites
                      in the artificial and natural salt                   100-
                      marsh during July 1988. Units
                      are C2H4 nmoles/g soil per hr
                      (*10-4). Data are from Zalejko                       80-
                      (1989) and Zalejko et al. (1989).
                                                                           60-



                                                                           40-



                                                                           20-
                                                                                     Artificial Marsh         Natural
                                                                                                               Marsh





                                                                           0.012-     (a)     R = 0.82
                      Figure 111.3.        Relationships                                      P = 0.0001
                      between rates of N-fixation
                      (acetylene reduction) and (a) soil                   0.010-
                      organic matter content and (b)
                      belowground biomass. Each point                      0.008-
                      represents      an      individual
                      measurement. Units are C2H4                          0.006-
                      nmoles/g soil per hr (* 10-4). Data
                      are from Zalejko et al. (1989).                      0.004


                                                                           0.002
                                                                                 0.1             0.2             0.3
                                                                                       Organic Matter (%        dry wt)


                                                                         40-     (b)     R = 0.55
                                                                                        P = 0.005

                                                                         30 -



                                                                         20 -



                                                                         10 -



                                                                           0
                                                                            0           2           4
                                                                                Belowground Biomass (g dry wt,'


                                                                   22






                                                  Assessment       Case Study

                                                                       higher (Figure 111.6), and percent organic
                        Nitrogen dynamics in natural vs.               matter in sediments was 2.4 times higher in
                    man-made salt marshes (modified from               the natural marsh. Total nitrogen in soils
                    Langis and Zedler 1989, and Langis et al.          was highly correlated with percent organic
                    in @press). Nitrogen levels in sediments,          matter (Figure 111.7).
                    pore-water and above-ground vegetation in
                    the constructed salt marsh were compared               Clearly, nutrient dynamics in the
                    with those in the natural Paradise Creek           constructed marsh are not comparable to
                    Marsh. Sampling sites were the same as             those of the natural marsh. Since in both
                    for nitrogen fixation (above).                     marshes sediment nitrogen levels (TKN)
                                                                       were correlated with percent soil organic
                        Nitrogen levels (ammonia, nitrate plus         matter, we believe that belowground
                    nitrite, and total Kjeldahl nitrogen [TKNI)        organic matter must accumulate in soils for
                    were significantly higher (P<0.01) in the          nitrogen levels to reach those of the natural
                    natural than in the man-made marsh in all          marsh.
                    the compartments examined. Phosphorus
                    levels were likewise higher in the natural             Through time, we expect the marsh soil
                    marsh (Figure IIIA). The magnitude of              to develop and for organic matter and
                    differences in nitrogen concentrations             nutrients to accumulate. However, in two
                    between the natural reference marsh and the        years of sampling nitrogen concentrations,
                    constructed marsh were as follows: 2.4             there was no indication of an increase.
                    times higher for sediment total N and              Much longer-term studies are needed to
                    extractable NH4; 9.4 times higher for poTe-        determine how rapidly wetland soils can
                    water NH4 (Figure 111.5) and 0.2 times             develop and how long it may take for
                    higher for foliar nitrogen in cordgrass.           constructed marshes to achieve the nutrient
                    Aboveground biomass of plants was much             status of natural marshes.



                    Figure IHA Total nitrogen (TKN) and phosphorus determined in sediment core samples
                    in May 1988 from the natural and man-made marshes. Differences in total nitrogen means
                    were highly significant (P<0.001) while total phosphorus values- were not. The low N/P
                    ratios are indicative of nitrogen limitation. Bar = 1 s.e.



                                   3-

                                              NATURAL




                                   2-

                              V                                      MAN-MADE
                              -P
                              E






                                   0
                                           TOT-N TOT-P             TOT-N TOT-P






                                                                 23






                                         Assessment Case Study


                Figure IH.5. Ammonium levels of pore-water samples collected September 16 and
                November 15, 1988. Differences between sites were highly significant (P<0.001). Bar1
                s.e.






                              4-
                                     NATURAL


                              3-



                        E    2-

                        z


                                                        MAN-MADE



                            0
                                  SEPT16 NOV15       SEPT 16 NOV 15







                Figure M.6. Above-ground biomass of cordgrass collected July 15, 1988 from 0.25-m2
                quadrats. Differences between sites were highly significant (P<0.001). Bar I s.e.



                           140-


                           120-


                     C4    100-
                     E
                     La
                     C4    80-

                           60-


                           40-


                           20-


                            0
                                    NATURAL            MAN-MADE









                                                     24






                                              Assessment Case Study


                Figure 1H.7. Regression -of sediment total nitrogen (TKN) over percent organic matter.


                               5
                                           y    0.1094 + 1.1058x R = 0.97

                               4-
                      W


                               3
                                                                A 0


                               2-

                      Cr
                      0
                      0-



                               0
                                 0            1           2          3           4.
                                               TKN (mg/g so! I dry wt)





                    Epibenthic invertebrate distri-                    After four years, this marsh had not
                butions in natural vs. man-made salt               developed its natural food chain support
                marshes (modified from Rutherford and              function. As cordgrass cover increases,
                Zedler 1989; details in Rutherford 1989).          it should facilitate recruitment of the
                There were significantly more individuals          invertebrate community; however, it is
                (2-4x) and more invertebrate species in a          not yet clear whether the constructed
                natural marsh at San Diego Bay than in             marsh provides the required quantities
                the 4-yr-old man-made marsh, comparing             and qualities of food for native
                the same low-marsh elevations (Figures             invertebrate populations to develop their
                111.8-111.9). All animals were trapped in          natural abundances and to persist in
                litterbags filled with dried cordgrass. The        perpetuity.
                most abundant species was a larval
                Dipteran, Pericoma sp., which was
                significantly more abundant (up to 9x) in
                the natural marsh (ANOVA, p< 0.05).
                An anemone, Diadumene franciscana,
                was found only in the natural marsh. In
                the man-made marsh, there were
                significantly more Hemigrapsus crabs in
                all sites sampled. In the natural marsh (at
                ca. 0.3 m above MSL), areas with 80-
                100% cover of cordgrass supported twice
                as many invertebrates as areas with 0-
                20% cover. At an elevation of 0.5 m
                above MSL, the numbers of species and
                individuals were similar for areas with             Polychaete worm
                high cover at the two marshes.
                                                                    (Nephthys caecoides)


                                                             25






                                           Assessment Case Study




                  Figure 111.8. Mean number of individuals per litterbag in areas of low elevation with
                  high (80-100%) vs. low (0-20%) cover of cordgrass vs. high elevation with high cover.


                              300-                            MAN-MADE
                                                              NATURAL


                         CO   200-
                         M
                         W



                         >    100-
                         a
                         z

                         LL
                         0

                               0-
                                  lo elev./hi cov lo elev./Io cov hi elev,


                                              MARSH SITE







                  Figure 111.9. Mean number of species per litterbag in areas of low elevation with high
                  (80-100%) vs. low (0-20%) cover of cordgrass vs. high elevation with high cover.


                                          MAN-MADE
                              12          NATURAL


                               10-


                               8-
                         Uj

                               6-

                         IL
                         CL
                         Cn    4-
                         U.
                         0
                               2


                               0
                                  lo elev./hi cov lo elev./lo cov hi elev.
                                              MARSH SITE






                                                       26






                                                   Assessment Case Study

                       Channel fishes and benthic                        Connector Marsh: yellowfin gobies
                   invertebrates. The requirements for                   (Acanthogobius flavimanus) and sailfin
                   functional equivalency of the channel fish            mollies (Poecilia latipinna). With the
                   and invertebrates in the Biological                   exception of one sailfin molly found in
                   Opinion (US FWS 1988) were that the                   F/G Street marsh, these species were
                   constructed marshes provide 75% of the                found exclusively in the constructed
                   species and 75% of the individuals found              marshes.       Generally, opportunistic
                   in the reference marshes. An extensive                nonnative species such as these are much
                   sampling program was designed to                      more successful in colonizing disturbed
                   understand how the constructed channel                habitats. Little is known about the
                   system has developed and to assess its                specific impact that these species have on
                   functioning in relation to natural                    the native species. Yellowfin gobies are
                   channels.                                             identified as voracious predators, and it
                                                                         may be assumed that they have some type
                       Channel organisms were sampled at                 of impact on the native community
                   three stations in the Connector Marshes               through predation. Likewise, sailfin
                   and four in the natural (reference)                   mollies are very similar to killifish in their
                   marshes within SRWC (Table 111.4).                    life history, and may have a competitive
                   Fish and invertebrates were sampled in                effect on this species. The effect of these
                   June 1989, October 1989, and January                  species on the channel community should
                   1990. At each station, blocking nets                  be investigated further.
                   were used to create a sampling area
                   approximately 10 rn long. A beach seine                   The sediments and channel
                   was repeatedly pulled through the sample              configuration of each station differed,
                   area until the fish catch per unit effort             providing a spectrum of habitat types
                   declined. Individuals were identified,                within the wetlands complex (Table
                   measured and released.               Benthic          IIIA). Because of this, a generalized
                   invertebrates were sampled adjacent to                comparison of the Connector Marsh
                   each station with 9 cores using a clam                stations with all of the reference marshes
                   gun (0.018 m2 surface area) to a depth of             would be insufficient to evaluate the
                   20 cm. Samples were preserved and                     specific stations. Instead, a similarity
                   retained for laboratory identification.               index was used to compare the individual
                                                                         sites.
                       The fish community. In               com-
                   paring the total fish caught over the three               For each sampling station, the
                   sampling dates, the natural marshes                   numbers of individuals sampled was
                   contained 15 species of fish. The Con-                totaled for each species over the three
                   nector Marsh stations, when combined,                 sampling dates. The relative abundance
                   contained all of these species and more.              of each species was calculated for each
                   The average number of individuals caught              station (Table 111.5). From these relative
                   at the connector marsh stations over the              abundances, an index of % similarity was
                   three sampling periods was 630,                       calculated (Sim. = 1[min. a,b], where a
                   compared to an average catch of 610 fish              and b are relative abundances in the two
                   at the reference marsh stations. This                 samples being compared).
                   indicates that for year 5, with 3 sampling
                   periods, the Connector Marsh has 100%
                   of the species and similar numbers of
                   individuals as are found in the reference
                   marshes at SRWC.

                       The evaluation of functional
                   equivalency is tempered by the
                   occurrence of two exotic species in the


                                                                   27






                                                    Assessment Case Study


                     Table HIA Description of channel stations at the Connector Marsh and other sites of the
                     Sweetwater River Wedand Complex (SRWC).

                                                                                 DescriRtion
                     Constructed channels
                     (Connector Marsh, CM)

                     Stn.2 South CM                  Coarse mud bottom. Steep bank on one side, gently sloping
                         east channel                    on the other. Max depth at low tide is approx. 0.75 m.
                                                         Occasional deeper areas with 50 gal. barrels on the bottom.
                     Stn.3 South CM                  Soft mud, sloping banks on both sides. Completely intertidal
                         .west channel                   (max depth at low tide is approx. 0.0 m).
                     Stn.7 North CM                  Soft mud, with medium sloping banks on both sides.
                                                     Max depth at low tide is approx. 1.0 m.

                     Natural channels

                     Stn. 1 . Isla Flaca,            Sandy mud with gentle, slope on one side and steep, eroding
                         Eastern tip                     bank on the other. Max depth at low tide is approx.
                                                         0.75 rn. Sweetwater River flows diectly out this course.
                     Stn.4 Sweetwater Marsh,         Soft mud/silt channel; some areas with dense clarn shells (dead).
                         main channel                    Steep banks up to the marsh plain on both sides.
                                                         Max depth at low tide is approx. 1.25 m.
                     Stn.5 E St. Marsh,              Soft mud channel with varying depths. Generally steep banks
                         main channel                    on both sides to a marsh plain. Max depth at low tide is
                                                         approx. 0.75 m.
                     Stn.6 F/G St. Marsh,            Very soft mud/silt bottom. Low bank that is steep on one side
                         main channel                    and sloping on the other. Sluggish but regular tidal
                                                         flushing. Maxdepthatlow tide is approx. 0.75 m.





                         Comparisons of the fish communities
                     within the Connector Marsh (Table 111.5)
                     indicate 72% similarity (of relative
                     abundances) between the two stations in             Table 111.5.        Similarity among
                     the west channel (South west and North              Connector         Marsh         stations.
                     west). Both western channel stations                Comparisons are based on relative
                     were dominated by topsmelt. These                   abundances of individuals for 3 seasonal
                     similarity comparisons also indicate that           samples in 1989-90. (Sim. = Y,[min.
                     the fish community in the eastern channel           a,b], where a and b are relative
                     (South east) is only about 20% similar to           abundances in the two samples being
                     each of the other CM stations. The                  compared)
                     eastern channel is, shallow, has a soft-
                     bottom, and is dominated by arrow                   CM Stations                   % Similarijy
                     gobies. The eastern channel has changed
                     considerably since construction of the              South west x North west              72.2%
                     Connector Marsh. Prior to 1984, it was              Southwest x Southeast                20.4%
                     the main tidal channel that directed flows.         Northwest x Southeast                20.8%




                                                                   28






                                                 Assessment Case Study


                  to Paradise Creek. After dredging of the             Table 111.6.        Similarity of fish
                  western channel, flows shifted to that               sampled in natural and constructed
                  deeper course, and sediments accreted in             wetland channel stations. Data are
                  ,the east channel. It is understandable that         for three seasonal samples in 1989-90.
                  the eastern channel has a different fish             Similarities are based on relative
                  community from the deeper channel that               abundances of species, as in the previous
                  was recently constructed.                            table.

                      The comparison of CM sampling                      CM          Sweet-     E      F/G Isla
                  stations indicates that there are at least           Channel        water      St.    St.    Flaca
                  two habitat types represented at the
                  Connector Marsh: 1) a mudflat/channel                North west      56%     41%    37% 34%
                  habitat (east channel) that is dominated by          South west      64%     47%    27%       39%
                  arrow gobies; and 2) deeper, subtidal                South east      56%     49%     15%     71%
                  channel habitats (west channels of North
                  and South CM) that are dominated by
                  topsmelt. Comparing species lists for the
                  Connector Marsh and reference channels
                  did not reveal this difference.                      the new channel of the constructed marsh
                                                                       does not closely resemble that of natural
                      The three Connector Marsh stations               channels. The highest similarity was
                  were then compared to those for the                  71%, comparing the accreting channel
                  natural marshes (Table 111.6). Data ftorn            along the eastern side of South CM with
                  the deeper, western channel of both                  the Isla Flaca channel, which receives
                  North CM and South CM are most like                  freshwater inflows from Sweetwater
                  those from the channel at Sweetwater                 River. The most obvious difference
                  Marsh (56-64% similar).                  The         between reference channel fish
                  Sweetwater Marsh channel has a high                  communities and CM channel
                  proportion of topsmelt. In contrast, the             communities is that several species tend
                  shallow, soft-bottom habitat of the                  to share dominance in the reference
                  eastern channel of CM is most similar to             channels, while CM channels are more
                  Isla Flaca. Both of these stations are               heavily dominated by a single species. A
                  distinguished from the others by their               more thorough evaluation of this pattern
                  large, adjacent intertidal mudflats, and             is needed.
                  both are dominated by arrow gobies.
                                                                           Benthic invertebrate commun-
                      Conclusions regarding fish                       ity. Benthic invertebrates were sampled
                  communities. The preliminary con-                    adjacent to each fish sampling station
                  clusion, based on 3 seasonal samples, is             with 9 cores using a clam gun (0.0 18 m2
                  that the US FWS criteria for fish species            surface area) to a depth of 20 cm. An
                  and abundance have been met, since all of            additional station was established in
                  the native fish species have been shown              Vener Pond where shorebirds are known
                  to occur in the constructed marsh                    to feed.    Invertebrate samples were
                  channels and since densities of fishes are           preserved and retained for laboratory
                  very similar to reference channels.                  identification.
                      Two functional differences need to be                Sampling of the benthic invertebrate
                  explored further.       First, non-native            community of the constructed marsh is
                  species have colonized the constructed               not complete. Laboratory examinations
                  marshes, and their influence on native               and counts have been done only for the
                  populations is unmeasured. Second, the               June and October 1989 sampling periods.
                  fish community (relative abundances) of



                                                                 29






                                                     Assessment Case Study

                      The following summary of findings is                individuals as in the natural benthic
                      thus preliminary.                                   sampling sites. These calculations are
                                                                          clearly preliminary and are not
                          In all, 27 taxa were captured and               conclusions of the study.
                      identified throughout the wetland
                      complex; of these, 14 were found in
                      numbers of fewer than 5 in the combined
                      June and October samples (Table 111.7).                 The bird community. The object-
                      Despite the use of 9 cores per sampling             ives of marsh restoration include
                      station (a total area of 0. 16 m2), many            provision of foraging habitat for
                      stations had very low densities. The                endangered birds. Understanding how
                      results obtained to date show high spatial          the entire bird community uses the
                      and temporal heterogeneity in the sand              restored marsh is important to the overall
                      and mud cores, with several station                 functional assessment. Not only can we
                      samples having few animals, and one                 learn what functions the restored marsh
                      station (Vener Pond in June) containing             provides, we can also explore
                      173 individuals of a small snail.                   relationships among species and species
                      Combining both sample dates, totals                 groups to understand why certain uses
                      encountered ranged from 20 to 276                   occur or fail to develop.
                      animals.
                                                                              Extensive bird surveys were
                          The total number of individuals                 undertaken (Ashfield and Kus, unpub.
                      sampled was 683; standardizing the                  data). Detailed analyses and results will
                      numbers to area sampled indicates that              be provided in an M.S. thesis (Ashfield,
                      samples from the constructed channel had            in prep.). The following is an initial
                      54% as many individuals as the natural              evaluation of the data from the Connector
                      benthic sampling stations.                          Marsh, the Paradise Creek, and the Bay
                                                                          Shoreline. Sampling took place twice per
                          Of the 27 taxa, 11 were found in both           month for 13 months from March 1999
                      constructed and natural channel stations;           through March 1990 (except once per
                      there were 20 taxa in the natural channels          month in November 1989 and January
                      and 18 in the CM sampling stations.                 1990), for a total of 24 low-tide surveys.
                      Assuming no effect of greater sampling              We report on the information for low-tide
                      area (an assumption that may not be met             surveys only (high-tide uses were also
                      since there were 4 natural stations and 3           recorded).      We include only the
                      constructed stations), the similarity of            waterbirds (excluding gulls).
                      species lists is 58% (using the 2w/[a+b]
                      similarity index). Comparing the 11 taxa                Two sampling sites were selected for
                      of the constructed channel to the 20 found          comparison with the Connector Marsh
                      in natural channels suggests that only              (CM): Paradise Creek (PC) and the Bay
                      55% of the naturally occurring taxa have            Shoreline (BS), which is just west of
                      established in the Connector Marsh                  Gunpowder Point. The rationale for
                      channels by the October sampling date.              comparing CM to PC is that PC habitat
                      These are preliminary calculations, and             was damaged and replacement of
                      the similarities will most likely change            functional losses there was part of the
                      once the full-year data set is analyzed.            objective of constructing CM.            The
                                                                          reason for comparing CM to BS is that
                         Preliminary summary of ben-                      CM has a larger proportion of intertidal
                      thic    invertebrates.        Of the two            flat than PC.
                      seasonal samples for which animals have
                      been identified and counted, the
                      constructed channels have 55% of the
                      species and 54% of the densities of


                                                                    30






                                                  Assessment Case Study


                   Table 111.7: Channel invertebrates found at the Sweetwater River Wetlands Complex,
                   June plus October 1989. Data are numbers per sampling station (number/O. 162 m2).

                                                F/G E          SW    Vener Isla S.isl. North S.isl.
                                   Taxa                      D=      Pond Flaca west            IsIs.      east TOW
                   Bivalves
                            Macoma nasuta
                      Tagelus californianus     1      0       2       0         0        1     2          4      10
                       Protothaca stanunea      4      16      37      0         2        18    10         25    112
                      Musculista senhousei      1      1       3       0         5        3     2          2      17
                   Gastropods                   2      0       0       0         0        0     0          0        4
                      Assiminea californica
                      Cerithidea californica    0      0       0       0         0        6     0          0        6
                           Acteocina inculata   9      1       13      16        1        30    3          13     86
                            Bulla gouldiana     16     0       0       173       11       0     0          0     200
                              Nassarius sp.     0      0       0       0         0        0     0          1        1
                   Crustacea                    0      0       0       0         1        0     0          0        1
                   Hemigrapsus oregonsis
                           Amphipoda            1      1       4       0         0        0     0          1        7
                           Orchestia traskiana
                   Anthozoa                     0      0       0       0         0        9     0          0        9
                           Ceriantharia
                   Polychaetes                  1      0       0       0         0        0     0          0        1
                           Capitellidae
                     Unknown capitelli&
                           Cirratulidae         0      0       0       0         0        2     2          1        5
                           Cirratidus cirratus
                                 Tharyx sp.     0      0       1       0         0        0     0          0        1
                           Eunicidae            2      0       0       0         0        1     0          0        3
                              Eunice valens
                           Glyceridae           0      1       0       0         0        0     0          0        1
                           Nereidae             0      0       1       0         0        0     0          0        1
                                 Nereis sp.
                           Orbiniidae           0      0       0       0         4        6     1          5      16
                           Scoloplos armiger
                        Phyllodocidae           0      0       15      0         10       0     0          0      25
                                 Eteone sp.     0      0       0       0         2        1     0          0        3
                           Spionidae            0      0       0       0         0        0     1          0        1
                           Polydora nuchalis
                           Polydora cornuta     11     0       0       26        0        3     0          0      40
                              Polydora sp.      2      0       0       2         0        12    0          6      22
                      Streblospio benedicti     26     0       0       59        0        12    4          10    ill
                   Fly larvae                   0      0       0       0         1        0     0          1        2
                   Chordata                     0      0       0       0         0        0     0          2        2
                           Ascidacea
                            Diplostoma sp.
                                                I      Q       Q       Q         Q        0     Q          D
                   Totals                       77     20      76      276       37    104      25         71   688




                                                                 31






                                                    Assessment Case Study

                                                                         western sandpipers, and in the area of
                         The three census sites are not identical        intertidal flats,      Because western
                     in size or physiography- The Paradise               sandpipers are so abundant at BS, their
                     Creek site was larger but, because it is            numbers mask the importance of other
                     dominated by salt marsh habitat, it had             species. The largest total for dowitcher
                     the smallest area of intertidal flats. Field        sightings was at BS, as were totals for
                     estimates of the areas sampled at CM and            willets and marbled godwits.
                     BS were very similar at 6-7 ha. Of these,
                     the BS site was entirely intertidal flat                CM shares 18 species with PC and 18
                     habitat, while CM was a combination of              with BS (Table 111.8). The data on
                     flats, channel water, and marsh.                    relative numbers of sightings show
                                                                         moderate similarity for the top ten
                         Comparisons of CM with both                     species, which comprised 80-90% of all
                     PC and BS. Overall, the number of                   sightings. The similarity between CM
                     water- associated bird sightings was                and PC (77% for species lists and 62%
                     lowest in PC (less than 1/3 that at CM),            for sightings, Table 111.8) was greater
                     despite the fact that this census area was          than the similarity between CM and BS
                     larger than CM and BS (Table 1111.8). In            (57% for species lists and 53% for
                     the low-tide censuses, excluding gulls,             sightings). Thus, despite the fact that
                     PC had 23 species of waterbirds, CM had             CM and BS are more alike in having large
                     24, and BS had 39. Using these data,                areas of intertidal flats, CM and PC
                     PC and CM had about the same species                appear more similar in their bird
                     richness, but attracted fewer species than          communities. As an intertidal flat, CM
                     BS. Note that all sites would have longer           functions less well than BS, both from
                     species lists if gulls, high-tide surveys,          the standpoint of numbers of species and
                     -and land birds were included.                      numbers of sightings. As a channel-
                                                                         marsh system, CM and PC are
                        Neither the lower numbers of                     moderately similar in bird communities,
                     sightings nor fewer species seen at PC              with substantially more numbers of
                     can be attributed to sampling area, since           water-associated birds seen at CM than at
                     PC was the largest site; hence, the finding         PC.
                     of fewer sightings at PC than at both CM
                     and BS is real. The extensive cover of
                     salt marsh vegetation at Paradise Creek
                     and its single large channel (rather than a
                     highly dissected tidal creek system) is not
                     optimal habitat for large numbers of
                     water- associated birds.        PC does,
                     however, support dowitchers, willets,
                     and western sandpipers in fair
                     abundance.

                        The largest number of sightings was
                     at BS (nearly 3x as many as at CM and
                     over 9x as many as at PC). With its high
                     species richness and abundance of
                     waterbirds, BS is clearly the most-used
                     waterbird habitat of the three comparison
                     sites. CM is intermediate in waterbird
                     support functions, between PC and BS.

                        The three sites differed in the number                     Fiddler crab
                     of species encountered, in sightings of                      (Uca crenulata)


                                                                  32





                                                   Assessment Case Study

                   Table 111.8. Sightings of water-associated birds at three wetlands of the
                   SRWC. Data are for 13 months in 1989-90. Data are for low-tide and water-associated
                   species excepting gulls. The similarity of species lists was calculated as 2w/a+b, where
                   w=no. of species in common, a=no. of species at PC and b=no. of species at CM.
                   Relative data are provided only for species with at least 5% of the sightings in at least one
                   of the three sites. Similarity of relative sightings was calculated as Y,(mininum a,b), where
                   a=rel. sightings at PC and b = rel. sightings at CM, summed for all species, not just the
                   ones listed here).


                   Summ4a                                     PC                     CM                        BS

                   Total sightings; relative to x         0.31x                         x                   2.88x
                   Number of species sighted                 23                        24                      39


                   Relative number of sightings (% of site tot 1)
                                                                   au
                   Western sandpiper                      15.5                      38.9                      40.6
                   Dowitcher spp.                         25.0                      29.1                      11.7
                   Willet                                 20.0                       3.5                       7.2
                   Marbled godwit                           4.9                      2.1                       8.5
                   Least sandpiper                          2.1                      9.7                       0.7
                   Dunlin                                   5.7                      4.8                       1.7
                   Killdeer                                 4.3                      6.5                       0.1
                   Red knot                                    0                        0                      8.7
                   American coot                               0                     7.0                         0
                   Bufflehead                               6.6                      0.1                       -0

                   Sum for above 10 species (%)           84.1                      91.7                      79.2


                   Site cg=ari@ons (all species)                  CM with PC               CM with BS

                   Number of species in common                          18                         18
                   Similarity of species lists                       76.6%                      57.1%
                   Similarity of rel. numbers of sightings.          62.5%                      52.7%




                       Conclusions from the bird                          some of the qualities of the best mudflat
                   census data. The avifauna of SRWC is                   site of SRWC. Overall, there were more
                   abundant and species rich.                The          sightings at CM than PC, but far fewer
                   Connector Marsh provides habitat that is               than at BS.
                   somewhat like that of the marsh-
                   dominated Paradise Creek site and                          Overall evaluation of functional
                   somewhat like that of the Bay Shoreline.               equivalency. It is not easy to create
                   The relative numbers of bird sightings at              cordgrass ecosystems that are function-
                   CM are more similar to those of PC than                ally equivalent to natural ones. In a
                   the Bay Shoreline, indicating that the CM              recent attempt to simplify the complex
                   site can support many of the marsh birds               data comparing the two types of systems
                   (e.g., dowitchers, willets) but that it lacks          at SRWC, we summarized 11 data sets


                                                                   33






                                                    Assessment Case Study

                     that were gathered when the constructed             dated, and the habitat islands disappear
                     marsh was 4-5 years old (Zedler and                 from sight.
                     Langis in press). The resulting "index"
                     (Table M.9) indicates that the constructed              The shortcomings of the constructed
                     marsh was less than 60% functionally                marsh were not anticipated; on the
                     equivalent to the natural reference wedand          contrary, the site benefitted from exten-
                     (Paradise Creek Marsh).                             sive planning and biological advice from
                                                                         several agencies. Detailed assessments,
                                                                         such as the work reported here, had never
                     Table 1H.9. Functional equivalency of               been done in our cordgrass marshes, and
                     the constructed and natural cordgrass               no one knew what site characteristics
                     marshes comparing soils, nutrients,                 needed to be measured to predict what
                     plants, and epibenthos. Soil and plant              would limit ecosystem development.
                     data are from Langis et al. (in press)
                     except for plant heights (unpub. PERL                   The quantitative comparisons of con-
                     data). Epibenthic invertebrate data are             structed and natural cordgrass marshes
                     from Rutherford (1989).                             @Langis et al. in press) revealed signif-
                                                                         icant differences in substrate character-
                               Data set                                  istics that help to explain why trans-
                                                                         planted cordgrass is growing poorly.
                     Organic matter content                    51        The sandier soils (probably from alluvial
                     Sediment nitrogen (inorganic N)           45        outwash) have little organic matter and
                     Sediment nitrogen (TKN)                   52        little nitrogen. The low organic matter
                     Pore-water nitrogen (inorganic N)         17        content limits nitrogen fixation and
                     Nitrogen fixation (surface cm)            51        nutrient recycling by microbes. Thus,
                     N fixation (rhizosphere)                 110        cordgrass growth is limited. Because
                     Biomass of vascular plants                42        levels of these two causal factors did not
                     Fohar nitrogen concentration              84        increase during the study, we reserve
                     Height of vascular plants                 65        judgment on how long it will take for
                     Epibenthic invertebrate numbers           36        functional equivalency to reach acceptable
                     Epibenthic invertebrate species lists     78        levels. (Funds have been requested to
                                                                         continue comparisons through age 9.)
                     Average of comparisons                -57%
                     95% confidence limits               40-74%              Our understanding of the importance
                                                                         of  soil organic matter and nitrogen
                                                                         suggests corrective measures for future
                                                                         restoration sites, and experiments are
                         Inclusion of data on fishes, channel            now underway to test the ability of a
                     benthos, and birds failed to increase the           variety of soil amendments to accelerate
                     overall similarity. Although fish species           the development of constructed cordgrass
                     lists were 100% similar for the two sites'          marshes. As the science of habitat
                     the bird for which the marsh was                    restoration advances, it should be
                     designed (light-footed clapper rail) was            possible to achieve greater than 60%
                     not yet using the constructed marsh.                functional equivalency. At the same time,
                                                                         as scientists continue to understand the
                         A major difference between the                  details of how natural wetland
                     constructed and natural sites is easily seen        ecosystems function, expectations for
                     during high tides. Tall cordgrass in the            restoration sites will also rise and the
                     natural marsh extends above the water,              attributes that are assessed will need to
                     providing a refuge for terrestrial arthro-          expand accordingly.
                     pods and cover for birds hiding among
                     the plants. In contrast, cordgrass in the
                     constructed marsh is completely inun-


                                                                   34





                      Sampling methods and comparative data from natural wetlands


                                                                        with personnel from the Pacific Estuarine
                     IV. Sampling methods                               Research Laboratory who monitor San
                                                                        Diego County wetlands in order to access
                      and comparative data                              the most recent reference data sets.
                     from natural wetlands                                  Second, use a hierarchical approach,
                                                                        insuring broad coverage with the most
                        Very few restoration or mitigation              general descriptors of ecosystem
                    projects have included adequate monitor-            condition (e.g., areas covered by tides)
                    ing programs, either in the extent of               and selected, individual sampling sites for
                    information gathered or the length of time          additional characteristics (e.g., plankton).
                    sampling has continued. In a review of
                    Section 404 permits (Clean Water Act) in                Third, obtain aerial photos annually
                    Washington State, only 31% of the                   and identify changes from year to year.
                    permits were found to require monitoring;           The US Army Corps of Engineers
                    those that did were typically of short              photographs the coastline each year and
                    duration (usually I year), and only                 has air photos available for purchase.
                    required data on vegetation coverage (cf.           Determine the tidal condition on the date
                    Josselyn et al. 1989). Likewise, the                and time that the photo was taken from
                    California Coastal Commission's                     tide tables. Photos at maximum high tide
                    Wetlands Task Force (Ray et al. 1986)               will indicate tidal coverage but obscure
                    found that the effectiveness of mitigation          vegetational changes, while photos at low
                    efforts has not been documented--56% of             tide will show the development of tidal
                    permits reviewed required some kind of              creeks in areas formerly dominated by
                    monitoring, but efforts ranged from                 plants.     Both will be useful for
                    simple visual observations to water                 interpreting changes in the overall
                    quality changes, with results that were             ecosystem.      Use photos to identify
                    not comparable. In many cases, results              locations where tidal creeks are
                    were not available and it was suspected             developing, to track the expansion of
                    that monitoring was not performed.                  vegetation onto newly graded tidal flats,
                                                                        to document changes in the linkages
                       There are three basic recommenda-                between the estuary and the surrounding
                    tions for an assessment program:                    landscape, and to quantify the portion of
                                                                        the adjacent landscape that is developed.
                       First, use standard methods and                  Aerial photo analyses should extend to
                    compare data with existing monitoring               areas beyond the wetland to include
                    programs. The methods proposed for                  potential enhancement sites.
                    monitoring are taken from published
                    literature and/or have been used to                     Recommendations for measuring
                    monitor other southern California coastal           ecosystem conditions and functions may
                    wetlands (Tijuana Estuary, San Diego                exclude some measures that are common
                    River Marsh, Los Penasquitos Lagoon,                in other regions because their measure-
                    Mugu Lagoon). The most important                    ment is too difficult or the results are not
                    considerations are the t),pe of gear used to        meaningful in this region. The prime
                    collect organisms (e.g., mesh size of fish          example is net annual primary pro-
                    seines), time of sampling (e.g., soil               ductivity of vascular plants (NAPP) and
                    salinity varies seasonally), size of sample         algae. Both are highly variable, the
                    unit (e.g., data on frequency of                    former on an annual basis, the latter on a
                    occurrence of plant species vary with               weekly basis. In addition, NAPP is
                    quadrat size), and location of sampling             grossly underestimated but not to the
                    station (small changes in topography                same degree for each species in the region
                    affect species composition). Persons                (Onuf et al. 1978). Thus, it is nearly
                    who supervise and carry out sampling                impossible to obtain data that can be
                    should interact (e.g., exchange reports)            compared from site to site.

                                                                  35





                     Sampling methods and comparative data from natural wetlands


                     Table IV.1. Ecosystem attributes to be considered in assessing how well constructed
                     wetlands replace the functions of natural wetlands:


                     Attribute and Measures                                      Reason for Analyses

                     Hydrology*
                         Current velocity and distance from tidal inlet          Tidal circulation
                         Water levels at various tidal cycles                    Tidal lags, inundation regime
                         Salinity of water and soil*                             Relation with strearnflow

                     Topography
                         Elevation% slope                                        Emsion, accretion

                     Soils
                         Texture                                                 Drainage, resilience of soil
                         Organic matte?                                          Nutrients, resilience of soil
                         Toxic substances                                        Biological accumulation
                         Redox                                                   Indicates drainage, organic
                                                                                  matter, anaerobiosis
                         Sulfides and pH                                         Potential for acid sulfate
                                                                                  soil formation

                     Nutrient dynamics
                         Nitrogen fixation rates                                 Availability to producers
                         Inorganic nitrogen in sediments and pore water          Potentially limiting nutrient
                         Denitrification rates                                   Nitrogen recycling
                         Organic matter decomposition                            Nutrient mineralization
                         Nitrogen mineralization rates

                     Algae
                         Cover by dominant type*                                 Food for invertebrates
                                                                                 Potential for nuisance blooms

                     Vascular plants
                         Total stem length (m/m2) of cordgrass                   Estimates standing crop
                         Cover of vascular plants*                               Shifts in dominance
                         Density of rare annual plants                           Population persistence and growth

                     Consumers
                         Decomposers and shredders                               Food chain support
                         Aquatic insects                                         Indicators of water quality,
                                                                                  food chain support
                         Terrestrial insects, especially pollinators             Food chain support; control
                            and predatory insects                                 of herbivorous insects, pollination
                         Fishes* and invertebrates*                              Food chain support
                         Birds*                                                  Food chain support
                         Reptiles and amphibians                                 Food chain support
                         Mammals                                                 Food chain support

                     *Highest priority components to assess



                                                                    36





                     Sampling methods and comparative data from natural wetlands


                                                                         much tidal circulation was improved by
                            1. Hydrologic                                excavation of intertidal habitat.
                                                                         Placement of tidal staffs (simple,
                                 functions                               graduated measuring sticks) facilitates
                                                                         location of data loggers at comparable
                                                                         elevations. Measurements are made in
                                                                         both man-made and reference wetlands
                       The most important forcing function               simultaneously to determine if the
                   of a coastal wetland is its hydrology, and            constructed system behaves similar to a
                   readers are referred to hydrologists to               natural wetland.        Measurements at
                   understand the hydrodynamics of coastal               increasing distances from the tidal inlet
                   wetlands. In almost every management                  help to reveal any obstructions or
                   planning effort, the bulk of the effort               bottlenecks in the main channels. The
                   goes into the characterization of the                 identification of a sill or hardpan that
                   hydrology of the system and use of                    restricts tidal flows will help determine
                   models to predict changes in the depth                whether there is potential for increased
                   and circulation of the system under                   tidal prism and whether such an
                   different management (e.g., dredging)                 obstruction needs to be removed.
                   regimes. This manual gives only the                   Finally, measurements before and after
                   briefest introduction to hydrologic                   the construction of new intertidal habitats
                   functions.                                            should show the effects of the newly
                                                                         created marsh on total-system hydrology.
                       Objectives. The objectives of a                       To characterize tidal flushing, the tidal
                   hydrologic survey are often to determine              heights are plotted with time (24-hr cycle)
                   the system's tidal prism and the size of              for each location. On the coast, the
                   tidal prism needed for self-maintenance of            minimum tidal amplitude occurs in spring
                   the ocean inlet, to characterize tidal                and fall, and the maximum in summer
                   flushing, and to understand the influence             and winter; lowest tide levels occur in
                   of tidal circulation on the ecosystem.                daytime in winter and at night in summer.
                   Three hydrologic features are of special              Tidal conditions are modified within the
                   ecological interest- -inundation patterns,            estuary. Reduced amplitudes and more
                   salinity regimes, and water column                    delayed peaks occur at increasing
                   stratification. Understanding the flooding            distances from the ocean inlet. Increased
                   and drainage patterns of tidal channels is            amplitudes and shorter lag times are
                   also extremely helpful in selecting                   anticipated following dredging or grading
                   sampling times for fishes and other                   operations that increase tidal prisms, and
                   channel organisms. Knowing how the                    such measurements would indicate
                   system deviates from predicted tide levels            improved tidal flushing.
                   on standard tables helps one arrive at the
                   sampling station when the water levels                   Elevation. The hydrologic condi-
                   are appropriate for the type of data being            tions of intertidal sites are determined by
                   collected. Maximum and minimum water                  measuring elevations relative to the
                   levels within a tidal system can differ by            National Geodetic Vertical Datum, i.e.,
                   2 hours or more.                                      the 1929 mean sea level, which is an
                       Inundation regime. Remote data                    average of data for the preceding 19
                   loggers are used to measure depth and                 years. Distributions of salt marsh plants
                   duration of tidal inundation (to estimate             are often referenced to this standard
                   tidal lags and tidal amplitude damping)               datum; however, it must be remembered
                   for selected tidal cycles prior to wetland            that the inundation regimes of a specific
                   alteration and following construction of              elevation may differ for various locations
                   wetland habitats.        Measuring tidal              within an estuary. Because tidal maxima
                   amplitudes and lag times will show how                and minima are damped at the inland
                                                                         extent of tidal creeks, and because peaks


                                                                  37





                       Sampling methods and comparative data from natural wetlands


                     lag behind conditions at the ocean inlet,           possibly warmer) water may float over
                     the inundation regime for an elevation of           the more saline/cooler seawater. In late
                     0 ft or m NGVD at the mouth may differ              summer, the pattern of stratification may
                     significantly from that at the most inland          reverse, with warmer hypersaline water
                     edge of the estuary.          In addition,          overlying seawater.
                     microtopographic features of the intertidal
                     zone may impede inundation or drainage,                 To characterize water column
                     such that one site at I ft NGVD may be              stratification, water salinities and
                     well drained, while another impounds                temperatures are taken monthly at selected
                     high tide waters. Thus, elevation is a              sampling stations. Temperature is first
                     general indicator of inundation regimes,            taken at the surface and at the bottom; if
                     not a precise measure of habitat                    there are differences, additional sampling
                     conditions.       Elevation should be               at 10-cm vertical intervals should be done
                     measured as a general descriptor, but one           to determine where the thermocline
                     should not assume that the same absolute            exists.    Since estuarine water tem-
                     elevation will have the same                        peratures vary with the tidal condition,
                     environmental conditions.                           the time of day, the storm condition, and
                                                                         the season, these measurements are more
                         11igh precision is needed in elevation          useful for determining whether the water
                     surveys.     Salt marsh vegetation is               column is stratified, than for char-
                     extremely sensitive to slight differences in        acterizing an "average" water temper-
                     tidal inundation, and plants that thrive at         ature. To obtain average water temper-
                     one elevation may yield to another species          atures, we recommend using continuous
                     if the topography is 10 cm (4 inches) too           sampling with a data logger to record
                     high or too low. For mapping of wetland             conditions during both spring and neap.
                     habitats and for marking sites for                  tides, over 24-hour periods.            Such
                     vegetation transplantation, 30-cm. (1-foot)         detailed data would be needed for
                     contours are the coarsest intervals that are        scientific studies and modeling of water
                     useful.                                             circulation.

                         Elevations are measured relative to                 Additional indicators of poor tidal
                     benchmarks near the estuary. Pro-                   flushing include phytoplankton blooms
                     fessional surveyors may be needed to                (pea-soup green water) and dense mats of
                     establish benchmarks near study sites, if           macroalgae. Macroalgal cover can be
                     these are not present. An automatic level           estimated at the water salinity stations,
                     (e.g., Wild Instruments) and calibrated             distinguishing epibenthic from floating
                     stadia rod are used to measure and/or               algae (see water quality methods).
                     mark additional elevations at the site.
                     Elevations of all systematic sampling                   Reference data. Williams and
                     stations are determined in this manner.             Swanson (1987) compared tidal flushing
                     While reference data are nearly alwa i
                                                                         data from several Tijuana Estuary stations
                     feet and inches in US publications, the             with data from a nearby tide recording
                     metric equivalents should also be reported          station (San Diego Bay at Broadway
                     for international comparisons.                      Pier). They found differences in tidal
                                                                         amplitudes and in the times of minimum
                         Water Column Stratification.                    and maximum water levels. Data from
                     Impaired tidal flushing can also be                 three stations are replotted in Figure 1. 1.
                     detected through measurements of water              The greatest differences between stations
                     temperature and salinity. In sluggish               within Tijuana Estuary and the Bay are in
                     channels, water columns become                      the amplitude between higher high and
                     stratified, with surface and bottom water           lower low water and the lag in outflow
                     differing in either temperature or salinity.        following. the higher water. The large
                     In . winter, following rainfall and                 volume of water flowing into the estuary
                     strearnflow into the estuary, fresher (and


                                                                   38





                      Sampling methods and comparative data from natural wetlands


                    at higher high tide was held for a longer
                    time than the inflows of the lower high                Additional hydrographs are presented
                    tide. Flows out of Tijuana Estuary were            in Williams and Swanson (1987) to show
                    constrained by the shallow ocean inlet. It         other lags within Oneonta Slough in
                    was also clear that flows out of Oneonta           1986. About 1.5 km (5,000 ft) inland
                    Slough were constrained by the                     along Oneonta Slough, higher high water
                    narrowness of that channel's inlet, which          lagged 2 hours behind that at its inlet and
                    was due to overwash fans (ibid.). These            lower low water was a foot higher,
                    overwash constrictions to tidal flushing           indicating that inflows and outflows were
                    were removed by dredging in 1987 and               both constrained upstream along the tidal
                    an improvement in flow to Oneonta                  channel.
                    Slough was documented by resurveys of
                    channel cross-sections (Florsheim and
                    Williams 1990).





                    Figure 1.1. Hydrographs for two locations at Tijuana Estuary compared to uncon-
                    strained tidal flows at San Diego Bay. Data redrawn from Williams and Swanson (1987).




                                6-
                                                                                      Tijuana Estuary
                                                                                (Oneonta Slough inlet)
                          >     4-
                          a                                                                   Tijuana Estuary
                          z
                          4)                                                             (inside estuary inlet)
                          >
                                2-





                                0-



                          CR    -2-
                          LU                                     San Diego Bay
                                                               (Broadway Pier)


                                   0                1000               2000                3000                4000
                                          Hours, 8:00am Aug. 19               - 1 0:00arn Aug. 20





                                                                 39





                      Sampling methods and comparative data from natural wetlands


                                                                        nontidal period, channel water salinity
                         2. Water quality                               reached 60 ppt 7 months after closure.
                                                                        Estuary-wide die-offs of invertebrates
                                                                        (e.g., crabs and hornsnails) were noted.
                       Objectives. Water quality mea-                       More severe changes in water quality
                   surements are needed to document                     develop when inlet closure is combined
                   problems, such as sewage spills, and to              with a sewage spill or rainfall and runoff
                   predict biological impacts, such as fish             event. Over the past several years, Los
                   kills. The most thorough water quality               Pefiasquitos Lagoon has closed to tidal
                   investigations, i.e., those including tests          flushing during the warm summer and
                   of heavy metal concentrations and                    fall months. On two occasions, major
                   presence of organic toxins, will help to             freshwater inflows and salinity-dilution
                   predict the potential and risks for                  events occurred. The first was a major
                   invertebrates, fishes, and birds.          In        sewage spill; the second, an early rainfall.
                   southern California, the greatest risks to           Without tidal flushing, the non-saline
                   marine animals develop when the mouth                waters were impounded, and extreme
                   of an estuary or lagoon closes to tidal              salinity dilution occurred, followed by
                   flushing. Initially, water temperature               major fish and invertebrate kills.
                   rises, so that saturation concentrations for             Additional data are provided by
                   dissolved oxygen decrease. Microbial                 Nordby and Zedler (in press), including
                   activity increases, along with metabolism            evidence from Tijuana Estuary and Los
                   rates of all animals and plants; thus,               Pefiasquitos Lagoon that lowered water
                   overall oxygen consumption increases.                salinity reduces the species richness of
                   While algae may become more                          both fishes and benthic: invertebrates.
                   productive, high biomass will accumulate
                   in the surface water, shading plants in the
                   channel and creek bottoms, so that less
                   oxygen production will occur in the                      What to measure. Several factors
                   habitats occupied by benthos. Later,                 such as nutrient concentration, light
                   decay of algal cells and fronds by                   attenuation, dissolved oxygen, salinity,
                   decomposers will increase oxygen                     and temperature are recorded to assess
                   demand, and bottom waters will become                water quality. The aquatic organisms,
                   hypoxic (low in oxygen). In the absence              i.e., zooplankton and algae, also help to
                   of rainfall, evaporation will concentrate            characterize water quality. There are
                   the saline water trapped in the estuary,             limited data on planktonic algae, but no
                   and channels and creeks will become                  reference data for zooplankton. Sampling
                   hypersaline. Thus, with closure alone,               before and after restoration measures take
                   substantial changes in water quality will            place is important to determine the
                   develop.       The changes in Los                    changes in ecosystem condition.
                   Pefiasquitos Lagoon, during the 1979
                   closure, illustrate these patterns (Figure               Permanent sampling stations are
                   2.1-2.3). Comparative data are shown                 chosen in a stratified random manner, to
                   for sample dates before and after closure,           assure similar representation for all
                   as well as inside and outside the inleL              aquatic habitat types. Habitat types may
                       Much higher salinities were                      include deep channels, tidal creeks, deep
                   documented at Los Pefiasquitos Lagoon                saline ponds, brackish and fresh sections
                   in the 1950's, when the lagoon remained              of the incoming creeks, and freshwater
                   closed to tidal flushin for several                  ponds.    Stations should be sampled
                                               9                        biweekly, or at least monthly, to detect
                   consecutive years.       Channel waters              and account for seasonal as well as yearly
                   exceeded 60 ppt in 1959 (Carpelan                    patterns.
                   1969). At Tijuana Estuary, during a long


                                                                 40





                  Sampling methods and comparative data from natural wetlands


                Figure 2.1. Changes in water temperature at Los Peffasquitos Lagoon, before and after
                closure of the inlet on May 12, 1979. The "Stagnant Arm" parallels the barrier dune and has
                reduced tidal influence year round; the sampling station under the railroad (RR) bridge is the
                deepest site in the lagoon. Data are single measurements from the water surface (PERL,
                unpubl.).

                            30-
                                             Stagnant Arm
                        0
                        0


                            20-


                        C13
                                                                          Outside the Inlet
                        CL
                        E   io-
                                          Under RR Bridge
                                                               Lagoon Inlet Closed

                             0
                                0                    100                   200                    3@O
                                                            Julian Date





                Figure 2.2. Reference data for lagoon water salinity at the surface, comparing sites before
                and after inlet closure, as in Fig. 2. 1.

                            40-

                                     Outside the Inlet
                            30-                                          Stagnant Arm
                        CL
                        CL


                        7=  20-                                             Un  er RR Bridge

                        cc
                        Cl)

                            10-
                                                               Lagoon Inlet Closed

                              0-
                                0                   100                   200                    300
                                                          Julian Date
                                                                               d
















                                                           41





                            Sampling methods and comparative data from natural wetlands


                                                                            accumulate to bloom proportion,
                            Water temperature and dis.                      anaerobic conditions can develop at the
                        solved oxygen are measured using a                  channel bottom during the night. In tidal
                        dissolved oxygen -temperature meter                 channels, the . highest algal biomass
                        (e.g., Yellowsprings Instrument Model               would be measurable at low tide at the
                        YSI 5 1 B).                                         end of a neap tide series, when channels
                                                                            would not have been greatly diluted by
                            Water salinity     is measured to the           seawater.
                        nearest part per thousand using an
                        American Optical (or Reichert) salinity                 In each of the aquatic habitat types,
                        refractometer.     Alternatively, a YSI             water samples for phytoplankton analysis
                        Salinity Meter and probe can be used for            can be collected in a simple plexiglass
                        ease in sampling vertical salinity profiles.        tube of 2-cm internal diameter, which is
                        Both the refractometer and salinity meter           the length of the water column being
                        read salinity in parts per thousand.                sampled (e.g., I m).         This tube is
                                                                            lowered vertically into the water column
                            Light attenuation is measured                   to ensure sampling from all strata, then
                        using a submersible light meter (e.g., Li-          sealed at the top and drained into the
                        Cor), sampling at the surface and at the            sample bottle. This sampling can be
                        bottom, with the depth between                      concurrent with the quarterly zooplankton
                        measurements recorded.              Several         sampling, utilizing the same stations.
                        different units can be used; the
                        measurement of interest is % attenuation.               Phytoplankton biomass is estimated
                        The extinction coefficient is k = [log I0 -         as  chlorophyll a concentration using
                        log Iz]/z, where 10 is the amount of -light         either the fluorometric technique or
                        at the water surface and Iz is the amount           extraction and measurement of
                        of light at depth z. A simpler measure,             absorbancy using a spectrophotometer.
                        for deeper water bodies is to lower a               The data in Figure 2.4 were obtained with
                        Secchi disk (a 20-cm diameter disk) from            the latter method, extracting the pigment
                        the shady side of a boat or pier. and               in 90% acetone, measuring absorbancy at
                        determine the depth at which it is no               663, 645, and. 630 nm (subtracting
                        longer visible.                                     absorbancy at 750 nm from each
                                                                            reading), and applying the formula, Chl a
                            Nutrients are collected in water                     11.64Abs663 - 2.16Abs645 +
                        samples using the same techniques as for            O.lAbs630 (Strickland and Parsons
                        phytoplankton. Samples can be frozen                1972). Results (mg pigment per liter of
                        and analysed for nutrient concentration at          acetone), divided by liters of seawater
                        a later time, but more reliable                     filtered, will yield micrograms of pigment
                        measurements are obtained on fresh                  per liter of seawater      milligrams per
                        samples that have been kept on ice                  cubic meter).
                        between the site and the lab. Wet
                        chemistry techniques for nutrient analysis              At present, there   are no exhaustive
                        are time consuming and routine analyses             data sets for coastal  wetland channels.
                        are best conducted on an autoanalyzer               However, the San Diego Regional Water
                        (e.g., Technicon Instruments Inc.),                 Quality Control Board has comparative
                        which automates the process.                        data sets for several lagoon sampling
                                                                            stations over a limited time period.
                            Algae. In aquatic ecosystems, algae             Experimental studies (Fong 1986, Fong
                        are the base of the food chain. While               et al. 1987) have addressed the role of
                        measurements of algal populations are not           nutrient additions to coastal water bodies.
                        very good estimators of primary
                        productivity, they are useful indicators of             Visual estimates of the percent of the
                        eutrophication and tidal flushing (cf.              water surface covered by macroalgae
                        Figure 2.3).      When phytoplankton                should be made at the same stations, and


                                                                     42





                        Sampling methods and comparative data from natural wetlands


                   the genus noted (usually members of the              these communities should be sampled at
                   Chlorophyta, either Enteromorpha or                  high tide, all of the habitat types can be
                   Ulva). Permanent plots are marked for                included.
                   cover estimation, using a rectangular
                   shape to reduce variance, and a size that               Plankton nets with a mesh size of 35
                   is appropriate for the habitat type (smaller         microns are appropriate for collection of
                   for tidal creeks than main channels).                zooplankton samples. As most of the
                                                                        habitats are relatively shallow, oblique
                        Zooplankton. Sampling for zoo-                  tows from channel or lagoon bottom to
                   plankton can be done quarterly at the                the surface are made behind a boat that is
                   same stations as the fish and                        travelling parallel to the shoreline.
                   invertebrates, although prior to or on a             Samples should be fixed in the field in
                   different day, as the seining often                  formalin, and quantified microscopically
                   resuspends benthic particles, obscuring              using Sedgwick-Rafter counting
                   the samples. Experience has shown that               chambers. Zooplankton densities and
                   sampling for plankton is most efficiently            community composition can be assessed
                   accomplished by boat as the water is not             spatially and temporally. Sampling of
                   disturbed as much as when walking.                   plankton should be done seasonally under
                   This is true for the zooplankton, algae,             the same tidal condition (e.g., end of a
                   and physical/chemical sampling, and all              neap tide series), in order to reduce the
                   can be accomplished at the same time. As             effect of seawater dilution.





                   Figure 2.3. Comparisons of phytoplankton (as relative amounts of chlorophyll a ) at Los
                   Peflasquitos Lagoon. One sample was taken prior to inlet closure. Phytoplankton
                   concentrations buiJt up in the poorly circulated "Stagnant Ann" following closure. Note the
                   log scale. Due to questionable calibration of the spectrophotometer, absolute values for
                   concentrations are not valid; however, relative comparisons are permissible.


                             101
                                                                                        Stagnant Arm

                        IM   100
                        E
                        cts                                                            Under RR Bridge
                        >%   10'1                                                      Outside the Inlet
                        CL
                        0
                        1-   1072-
                        0


                                3'                 inlet closed on May 12,1979
                             10'  -                                     I                                   I
                                100                             Julian Date                               300




                                                                 43





                         Sampling methods and comparative data from natural wetlands


                                                                              quently, on the marsh productivity. To
                                     3.      Soils:                           date, there are only a few sites for which
                                                                              we have obtained detailed data on soil
                            Substrate qualities                               conditions. The theses of Swift (1988),
                                                               0              Cantilli (1989), and Zalejko (1989), and
                        and nutrient dynamics                                 the studies of Langis et al. (in press)
                                                                              provide a basis for understanding below-
                                                                              ground dynamics of the coastal salt
                           Objectives. Soil conditions have          a        marshes.
                       major influence on vegetation growth and
                       on organisms that inhabit the rhizosphere                  Sampling strategy.             All soil
                       of plants (e.g., amphipods, nematodes,                 sampling is done randomly along pre-
                       microbes). Four variables are especially               determined 10-12 m transects. The tran-
                       helpful in predicting the ability of a site to         sects should be along selected elevations,
                       support a functional salt marsh: soil                  so that replicate samples are under a simi-
                       salinity, nitrogen dynamics, organic                   lar tidal regime. Samples subject to sea-
                       matter concentration, and redox potential.             sonal variation (soil or pore water
                       Soil salinities control seed germination               nitrogen concentration, nitrogen-fixation,
                       and seedling establishment in the coastal              denitrification, soil or pore water salinity,
                       wetlands (Zedler and Beare 1986).                      redox potential, water content) should be
                       Concentrations that are either too high or             taken quarterly.
                       too low will alter vegetation composition
                       by restricting growth of even the most                    High variances among replicate
                       tolerant halophytes, in the case of extreme            samples are more often the rule than the
                       hypersalinity, or by allowing the invasion             exception for chemical parameters of
                       of cattails, bulrushes, and other glyco-               soils. This variability can be reduced by
                       phytes, in the case of prolonged periods,              compositing several samples before
                       of hyposalinity. Nutrient dynamics,                    analysis (Binkley and Vitousek 1989). In
                       organic matter, and redox conditions all               general, one should increase sampling as
                       interact to control- plant growth rates,               much as is practiable to improve the
                       which in turn affect the consumers that                estimate of the mean. Soil analysis time
                       live among the plant roots. Soils with                 is the usual limiting factor. Lloyd and
                       low organic matter will have low                       McKee (1983) have suggested a statistical
                       nitrogen-fixation rates and low supplies               procedure for determining the optimal
                       of the main nutrient that limits plant                 number of subsamples required by the
                       growth. Soils with high organic matter                 level of confidence desired. The number
                       will develop very negative redox                       of subsamples will depend on the degree
                       potential, which may restrict the growth               of variability of the measurements for the
                       of some marsh plants; Cantilli (1989)                  sediments of the particular area. For
                       showed that low redox affected the                     example, Langis et al. (in press) obtained
                       growth of pickleweed, but probably not                 acceptable levels of variation with 4-6 soil
                       that of cordgrass.                                     cores randomly selected along pre-
                                                                              established transects of 10- 12 m.
                           The patterns     of salinity, nitrogen
                       dynamics, organic matter accumulation,                    Bulk density. This parameter rep-
                       and redox potential vary in space and                  resents the weight of soil per unit volume
                       Aime. Wetland hydrology determines the                 including pore spaces. It is useful when
                       chemical and physical nature of salt                   the density differences of different soils
                       marsh substrate to a great extent (Mitsch              must be accounted for. In which case,
                       and Gosselink 1986). For instance, the                 properties such as percent organic matter,
                       aerobic- anaerobic conditions resulting                total nitrogen or moisture can be
                       from regular tidal flooding of these soils             overestimated in organic rich sediments
                       have a profound effect on the biogeo-                  when expressed on a dry weight basis
                       chemical cycles of nutrients, and conse-


                                                                       44





                   Sampling methods and comparative data from natural wetlands


                 because of the relative low weight of                all cases, measurements are made from
                 organic matter (Allison 1973).                       replicate sampling stations. Soil salinity
                                                                      is measured monthly, near the water
                     Bulk density is obtained by pressing             salinity sampling locations. Soil salinities
                 into the soil a thin-walled soil can with a          are also measured at the permanent vege-
                 cutting edge. The soil is then sliced                tation transects at the time of plant
                 smooth at the open end and oven-dried to             censusing, and in sites of special interest,
                 constant weight at 105'C. Bulk density =             such as planting locations for the salt
                 mass of soil in tube/volume, expressed as            marsh bird's beak and areas where weedy
                 g dry-wt/cm3 (Richards 1954).                        vegetation is invading.

                     Water content is measured as                         Soil cores are easily removed with a
                 weight loss upon oven drying divided by              2.5-cm-diameter soil tube (available from
                 dry weight of the soil sample. The soil              Forestry Suppliers), which is inserted
                 sample is dried to constant weight at 100-           about 20 cm into the soil. A subsample
                 110'C (Gardner 1986). Organic soils                  of the core is then analyzed for soil
                 have higher water-holding capacities than            salinity. A 5-cm segment from the 0-10-
                 mineral soils (except for clays).                    cm depth characterizes the upper root
                                                                      zone; and 20-30 cm the deeper root zone.
                     Particle size of marsh soils                     If the marsh soil is saturated with water,
                 should be assessed in the traditional                the salinity measurement can be made
                 method used by terrestrial ecologists,               immediately in the field, by expressing a
                 identifying sand, silt, and clay percent-            drop of soil water onto a salinity refrac-
                 ages using a hydrometer (Gee and Bauder              tometer (use one that is temperature-
                 1986), rather than the detailed size differ-         compensated, with a range of 0-150 ppt;
                 entiation used by marine ecologists                  available from most scientific supply
                 (Emery settling tube and phi values).                houses). Soil water is expressed by load-
                 Soils are characterized by type, with                ing a 10 cc plastic syringe (without ne  ,ed-
                 natural salt marshes likely falling in the           le) with 2 layers of #2 Whatman filter
                 clay to clay-loam types. At Tijuana                  paper that has been cut into 12-mm-
                 Estuary, lower marsh soils were gener-               diameter circles (punch from larger sheets
                 ally clayey, with 2-8% sand, 23-32% silt,            using a half-inch die). The wet soil is
                 and 46-58% clay (Zedler et al. 1980).                loaded by hand; the plunger is inserted,
                                                                      and a drop of water is forced onto the
                     Swift (1988) compared soil texture in            refractometer. Readings are in ppt.
                 man-made and natural marshes at Sweet-
                 water River Wetland Complex and found                    If the soil is too dry, the subsample is
                 coarser texture in soils of the marsh that           stored in a plastic bag (WhirlpakTm bags
                 had been graded to expose lower-                     are handy) and returned to the lab for
                 elevation strata. Paradise Creek (natural            artificial saturation with deionized water.
                 marsh) soils were clay lo"ams, while those           The standard method for preparing
                 of Caltrans Connector Marsh (man-made)               saturated soil pastes should be followed
                 ranged from loam to sandy loam. These                (refer to Richards 1954) and salinity
                 differences in texture, along with dif-              measured with a conductivity meter (e.g.,
                 ferences in soil organic matter (lower in            Lab-Line mho meter). This method is
                 the man-made marsh) appeared to be                   time-consuming, but soil samples can be
                 important to soil functioning, as there              refrigerated and processed in batches.
                 were also lower rates of nitrogen fixation           The conductivity results are not directly
                 and less evidence for sulfate reduction.             comparable with those from saturated
                                                                      soils, but salinities from all pastes are
                     Soil salinities are assessed to help             comparable with one another.
                 explain vegetation patterns and to track
                 the influence of freshwater inflows. In                  For comparison of the salinity of
                                                                      saturated soil pastes with other refrac-


                                                                45





                          Sampling methods and comparative data from natural wetlands


                        tometer measurements taken in the field,             Pore water chemistry can be evaluated in
                        water from the soil paste can be                     a convenient way by the use of wells that
                        expressed through filter paper and                   can be permanently installed in the sedi-
                        measured with the refractometer. Results             ments. Water should be sampled as soon
                        can be viewed as the soil salinity that              as possible after a high tide so that sedi-
                        would occur following rainfall.                      ments are sufficiently saturated. To
                                                                             obtain a fresh sample, each well must be
                            Reference data on soil salinity                  emptied with a syringe fitted with a vinyl
                        are available for several wetlands in San            tube (long enough to get to the bottom of
                        Diego County. A major factor that influ-             the well) and allowed to refill before
                        ences soil salinity is closure of the ocean          collecting the pore water sample.
                        inlet, as illustrated by comparing data
                        from Los Pehasquitos Lagoon (Figure                      Parameters such as pH, redox poten-
                        3. 1), which is often a closed lagoon, with          tial and salinity can be measured directly
                        data from Sweetwater River Estuary                   in the well and samples can be taken in
                        (Figure 3.2) and Upper Newport'Bay                   the laboratory for chemical analyses.
                        (Figure 3.3), which are always open to               Ammonium concentrations can then be
                        tidal flushing. Los Pefiasquitos Lagoon              measured with the hypochlorite-
                        soils become very hypersaline following              nitroprusside method and N03-+NO2-
                        evaporation and are measurably diluted               by the cadmium reduction method
                        following rainfall. The effects are                  (APHA 1986). The depth of sampling is
                        stronger for surface soils (0-5 cm) than             adjusted through the location of the slits
                        d'eeper in the profile (45-50 cm). In                and by inserting the wells at different
                        contrast, soils of tidally flushed wetlands          depths. It is possible to collect water
                        are mildly hypersaline for most of the               from a narrow or broad range of depths
                        year. With a nontidal system, surface                using such wells.- Water samples for
                        soil salinities are more variable than with          chemical comparisons must be collected
                        the ameliorating influence of tidal waters.          at similar tidal levels since Agosta (1985)
                           Long-term data on soil salinity have              found that NH4+ concentrations tend to
                        been recorded at Tijuana Estuary, as part            decrease as the water table goes down
                        of the salt marsh monitoring program of              and to increase as the water table comes
                        PERL (Figure 3.4). Soil salinity has                 back up. This would especially apply to
                        been measured in April and in September              creek banks where the level of the water
                        for 10 years, including changes following            table is strongly affected by the tidal
                        a major flood year (1980) and estuarine              action.
                        closure during a drought year (1984).                    The wells are constructed from plastic
                           Measurements to be done on                        (PVC) pipes (30-cm long, 2-cm inside
                        pore water. Since dissolved nutrients                diameter, 2.5-cm outside diameter), in
                        are readily available to plants, it is               which a series of vertical slits is cut at 2-
                        advantageous to sample pore water.                   cm intervals, from the bottom to approx-
                        These samples are representative of                  imately 17 cm. The slits are covered with
                        chemical conditions in the sediments. In             a piece of nylon screen (NitexTm, 100 to
                        anaerobic sediments, dissolved nitrogen              200 @=) held in place with a sleeve made
                        is mostly under the NH4+ and dissolved               from a thin PVC tube of dimensions
                                                                             similar to the well. Since small particles
                        organic forms, N03- being a transient                will get through the screen, particles
                        species. Ammonium and SRP (soluble                   should be allowed to settle, or it might be
                        reactive phosphorus) concentrations                  necessary to centrifuge or filter the
                        reflect exchange equilibria between dis-             sample with WhatmanTm GF/C filter
                        solved and solid phases, since NH4+ and              paper before analysis.
                        P04-2 are adsorbed on fine organic and
                        clay particles (Avnimelech et al. 1983).


                                                                      46





                    Sampling methods and comparative data from natural wetlands



                   Figure 3.1. Substrate salinity at Los Pefiasquitos Lagoon, a system that is often closed
                   to tidal flushing. Evaporation of sea water leads to hypersaline soils, while impounded
                   rainfall and strearnflow reduces salinity. Data are means (and ï¿½1 s.e.) of samples at the
                   surface (0-5 cm) and at depth (45 -50 cm) for n=21 stations. Data are from Eilers (198 1).



                                100-



                                80-


                           CL
                                60-
                                                                         45-50cm
                           'E   40-

                           C13
                           CO   20-
                                                                           0-5cm

                                  0-
                                           @ov    Jan     Mar     @ay     J'ul
                                               Month (1977-78)




                   Figure 3.2. Substrate salinity at Sweetwater River Estuary, a fully tidal salt marsh
                   adjacent to San Diego Bay. Data are means L+1 s.e.), for n=31 stations. Data are from
                   Eflers (1981).



                                100-



                                80-
                                                                          0-5cm
                           CL
                                60-


                                40-                                     45-50cm
                          C13
                                20-



                                 0
                                          Nov     Jan     Mar     May     Jul
                                               Month (1977-78)
                                                                  @45-50cr



                                                                47





                   Sampling methods and comparative data from natural wetlands


                  Figure 3.3. Substrate salinity at Upper Newport Beach, a fully tidal salt marsh. Data
                  are means L+ 1 s.e.), for n=25 stations. Data are from Eilers (198 1).



                            100-



                             80-

                         CL                                     0-5cm
                         CL
                             60-



                             40-
                         cis                                   45-50cm
                         CO
                             20



                               0-
                                      @ov   Jan    Mar    @ay   J1U1
                                          Month (1977-78)




                  Figure 3.4. Interstitial soil salinity (0-10 cm) at Tijuana, Estuary. Data are from the
                  lower marsh, at 102 sampling stations within the 1979 distribution of cordgrass, for April
                  and September sampling periods. Error bars (ï¿½1 s.e.) are generally too narrow to show.


                                                              (104)

                         100-




                         80-

                     CL
                     CL
                         60



                     CO
                     CO  40

                     0
                     U)
                         20-




                           0
                           1978      1980       1982       1984       1986       1988
                                       -@J-@@45-50cr











                                                     Year




                                                       48





                 Sampling methods and comparative data from natural wetlands


                   Soil pH can be measured directly in            Broome (1987) noted no suvival of
               pore water wells, using a pH meter and a           vegetation planted in soils of pH<3.
               combination electrode (cf. Figure 3.5). If
               pore water wells are not used, the                     Redox potential. This measure-
               electrode can be inserted gently into a            ment is important because of it plays an
               moist soil sample. If soil samples are too         important role in the biogeochemical cycle
               dry, they could be sealed in a plastic bag         of nitrogen and sulfur, and affects the
               and returned to the laboratory where this          mobility of heavy metals. As for pH, it
               measurement can be made on soil paste              can be easily measured by inserting a
               (see section on soil salinities). Soil pH          redox probe directly in the pore water
               could become a major concern in the case           sampling well.
               of acid sulfate soils. These soils can
               become extremely acidic following the                  Values obtained with the redox elec-
               oxidation of sulfides to sulphates and             trode must be standardized to measure-
               sulfuric acids. This situation occurs              ments obtained with the standard hydro-
               when tidal inundation is stopped and               gen electrode by adding the appropriate
               leaching of sulfates and sulfuric acid by          correction factor. The correction factor is
               rain is impeded by a high clay content             the difference between values measured
               (Linton 1969). Soil pH can vary by as              with ZoBell's solution (0.003 M potas-
               much of 2 units within a tidal cycle,              sium ferricyanide, 0.003 M potassium
               because of water infiltration or benthic           ferrocyanide and 0.1 M potassium
               biological activity (Wolaver et al. 1986).         chloride) and its theoritical Fh of +430
               Values lower than pH 4 are detrimental             mV at 25C (ZoBell 1946).
               to salt marsh plant establishment, since




               Figure 3.5. Soil pH measured in bore holes at Los Pefiasquitos Lagoon (LPL, n=21
               stations), Sweetwater River Estuary (SRE, n=31 stations), and Upper Newport Beach
               (UNB, n=25 stations). Data are means L+1 s.e.). Data from Eilers (198 1).


                             7.4-

                                          LPL
                             7.2-


                             7.0-


                     3:      6.8
                      CL
                                        UNB
                      0      6.6-
                     CI)

                             6.4-

                                        SFE
                             6.2-


                             6.0
                                          Nov       Jan        Mar      May        Jul
                                                     Month (1977-78)



                                                            49





                         -Sampling methods and comparative data from natural wetlands

                             Extractable NH4+ and N03-                        1000G) for 15 min. Absorption of the
                         +N02-. These inorganic forms of                      supernatant is measured at 600 nm on a
                         nitrogen give an estimate of potentially             spectrophotometer. Absorption values
                         available nitrogen in the soil.           To         are then compared to a series of standards
                         measure, put 10 g (wet wt) of fresh soil             (1.5 to 7% O.M.). Standards are pre-
                         sample of in a 125 ml Erlenmeyer flask;              pared by adding calculated amounts of
                         add 100 ml 2 M KCI; set on a wrist-                  sucrose to ignited sediments (750'C, 4
                         action shaker for 1 h; filter through                h). The main drawback of the method is
                         WhatmanTm no. I (the filtrate can be kept            that some of the refractory organic
                         frozen until analysis); analyze for NH4+             substances will resist the digestion.
                         with the automated phenate meth-od and                   Organic carbon. The refractory
                         for N03-+NO2- by the cadmium-                        organic carbon fraction could better be
                         reduction method (APHA 1986).                        accounted for with a second technique,
                         Artificial seawater should be used to                the modified Mebius procedure (see
                         prepare blanks and standards. In the                 Yeomans and Bremner 1988), where a
                         characteristically anaerobic sediments of            more thorough oxidation is obtained by
                         salt marshes most of the extractable N               digesting the sample at 1700C with
                         will be under the form of NH4+, N03-                 potassium dichromate and values of %
                         contributing very little to the N pool.              organic carbon are obtained directly by
                                                                              titration.
                             Total nitrogen. This is a mea-
                         surement of the total nitrogen in the soil               A CHN analyzer could also be used
                         and includes the organic and inorganic               to  get organic carbon measurements
                         forms. Nitrogen is either measured as                simultaneously with total nitrogen on
                         NH4+ after Kjeldahl digestion (APHA                  samples with unmeasurable levels of
                         1986) or directly with a CHN analyzer.               inorganic carbon. If inorganic carbon is
                                                                              present at a significant level (see Nelson
                            Percent organic matter. Both                      and Sommers 1982 for a discussion of
                         combustion and chemical oxidation meth-              methods) it is advisable to use the modi-
                         ods have been used to measure soil                   fied Mebius procedure (Yeomans-and
                         organic matter (0M.) content. Weight                 Bremner 1988). The Sims and Haby
                         loss upon combustion in a muffle furnace             procedure could also be used provided
                         overestimates O.M. when clay minerals                that standards are expressed as % O.C.
                         and/or carbonates are destroyed at high              instead of as % O.M.
                         temperatures. Swift (1988) measured
                         O.M. or wetland soils by combusting                      Nitrogen fixation could represent
                         samples at 7000C for 1 h and 4000C for 3             an important source of available nitrogen
                         h.   Values obtained at 7000C were                   for the generally nitrogen-limited salt
                         consistently higher (Table 3.1).                     marsh vegetation. The most used and
                                                                              most straightforward method involves the
                            Two wet digestion techniques are                  use of the acetylene reduction reaction,
                         recommended to avoid the problems of                 where the enzyme dinitrogenase is
                         carbonate or clay degradation. The rapid             capable of reducing C2112 as well as
                         oxidation technique (Sims and Haby                   dinitrogen (Hardy et al. 1968; Casselman
                         197 1) has provided satisfactory results.            et al. 1981). In this technique, C2112 is
                         Briefly, 10 ml of IN K2Cr2O7, followed               added to incubation vessels and dinitro-
                         by 20 ml of concentrated H2SO4 are                   genase activity is monitored. Although
                         added to a 1-9 (dry wt) soil sample in a             this method must be calibrated with an
                         125 ml Erlenmeyer flask. The slurry is               15N tracer to obtain absolute values,
                         swirled and allowed to react for 20 min,             comparisons can be made on the basis of
                         brought to a volume of 100 ml with                   nmoles C2H2 reduced per unit soil.
                         distilled H20 and centrifuged (at ca.500-


                                                                       50





                       Sampling methods and comparative data from natural wetlands



                     Table 3.1. Soil organic matter in the natural wetland remnant, Paradise Creek Marsh,
                     and the man-made Connector Marsh at San Diego Bay. Data are for soils seived with a 2-
                     mm mesh screen to remove roots (from Swift 1988).

                                                                     4000C for 3 hr                  7000C for 1 hr
                                                     ngth         0-5 cm         5-10 cm         0-5 cm        5-10 cm

                     Paradise Creek                  mean           4.90          4.86              8.14         9.24
                                    n=3              s.e.           (0.20)       (0.48)            (0.24)       (0.48)

                     Connector Marsh                 mean           2.21          1.61              4.34         4.17
                                    n=6              s.e.           (0.16)       (0.13)            (0.34)       (0.27)






                        For measuring nitrogen fixation, we
                     recommend the following procedure                           Nitrogen mineralization. Esti-
                     adapted from Zalejko (1989): In the                     mates of nitrogen mineralization rates in
                     field, soil cores are taken for root zone N-            the field can be obtained with the buried
                     fixation (10-cm deep by 8-cm diameter),                 polyethylene bag technique (Eno 1960).
                     and for surface N-fixation (1 cm deep by                Because plant uptake and leaching of
                     3 cm in diameter for surface N-fixation).               nitrogen is prevented, net mineralization
                     Cores are placed in a I-L mason jar and                 rates can be estimated as the increase in
                     tightly capped with a lid (equipped with a              NH4+ and N03 -+NO 2- (Pastor et al.
                     serum stopper). It is important to clean                1984). Sediment cores (8-cm depth x 5-
                     dirt off rims since jars must be air-tight.             cm diameter) are placed into 0.03 mm
                                                                             thick polyethylene bags; the bags are tied
                        The cores are incubated overnight in                 and replaced in their respective holes and
                     the dark at 220C, to allow microbial popu-              covered with approximately 2 cm of
                     lations to adapt. The next morning,                     sediment. At the same time, another soil
                     acetylene and ethane (as an internal stan-              core, adjacent to the plastic-enclosed
                     dard to account for leakage) are added to               core, is collected and immediately taken
                     jars with a syringe, yielding an atmo-                  to the laboratory for analysis of
                     sphere of 10% and 0.01%, respectively.                  extractable NH4+ and N03-+NO2-.
                     Concentrations Of C2H4 and C2116 are                    These polyethylene bags are impermeable
                     measured with a flame ionization detector               to water and permeable to gases such as
                     on a gas chromatograph. The headspace                   C02 so that constant moisture content can
                     gases are mixed by pumping the syringe                  be assured during the incubation while
                     plunger several times. Gas samples are                  permitting gas exchange (Gordon et al.
                     withdrawn from the jar head space on                    1987). After 14 days, the bags are col-
                     several occasions (after I to 5 h of incu-              lected and taken back to the laboratory for
                     bation). Samples (1 ml) are injected                    analysis. Increases in concentrations of
                     (injector temperature: 85'Q onto a 2 m                  extractable NH4+ and N03-+NO2- (an
                     PorapakTm N column. Pure nitrogen is                    estimate of net nitrification) are then
                     used as the carrier gas at a flow-rate of 30            calculated to estimate rates of
                     ml-min-1, the oven temperature is 50'C                  mineralization.
                     and the detector temperature 200'C.
                     Measurements are done on peak areas.



                                                                       51





                          Sampling methods and comparative data from natural wetlands


                                 4. Vegetation                                     Vegetation           maps. Aerial
                                                                              photographs are obtained to determine
                              composition and                                 overall vegetation coverage in each
                                        growth                                marsh. General attributes to obtain are
                                                                              the total area of each constructed marsh,
                                                                              the amount of open (unvegetated space),
                            Objectives. Wetland vegetation Iis                and the area of each type of vegetation
                        the most obvious and straightforward                  (e.g., lower intertidal marsh dominated
                        indicator of habitat condition. Surveys of            by cordgrass, mid-intertidal marsh
                        vegetation are needed to document the                 dominated by mixed succulents, high-
                        success of plant growth as well as to                 intertidal marsh dominated by various
                        assess the site's potential for supporting            species and with potential habitat for salt
                           mal populations.                                   marsh bird's beak). Next, representative
                                                                              subunits of each vegetation type in both
                            The species composition of habitats               the constructed and reference wetlands
                        within an area allows one to read the                 are selected for detailed sampling to
                        history of the site. Changes in vascular              determine if the plant communities are
                        plant    distributions        lag     behind          similar.
                        environmental changes, because most
                        species are limited in their ability to                   Approximate          elevations         are
                        become established even when the habitat              determined from a topographic map (one-
                        is appropriate. Thus, the vegetation is an            foot contour map needed) and used to
                        integrator of long-term conditions, more              locate and set the length of each transect
                        than a measure of current events. The                 (50-m transects: are useful, but shorter
                        presence of cordgrass indicates a long                lengths may be necessary in variable
                        history of good tidal flushing, but the               topography). To characterize the high
                        species may persist for many months or                marsh-upland transition area, the transect
                        even years after such conditions have                 should parallel the elevation band that
                        changed. The presence of cattails in a salt           contains that habitat.        About 40-50
                        marsh indicates that excess freshwater                stations should be established in each area
                        inflows occurred at some time in the past,            to be compared. Each transect should be
                        but does not prove. that flows are                    indicated on an aerial photo overlay.
                        currently being augmented. If a site has              Elevations should then be surveyed at
                        few species present, there are two                    each sampling station. Each transect
                        possible interpretations--the habitat may             should have a number, and the number of
                        be poorly suited for salt marsh                       sampling stations on each transect should
                        development, or the site may provide                  be recorded on the overlay.
                        suitable habitat but not yet support a
                        diverse vegetation due to isolation from                  Sampling stations should be located at
                        propagules or insufficient time for                   regular (5-m) intervals along permanent
                        establishment.                                        transects. Sturdy wooden stakes should
                                                                              be numbered with marine paint and
                           The plant species composition dictates             placed so they barely protrude above the
                        the suitability of sites for a wide variety           canopy. Tall stakes attract raptors that
                        of animals. Insects are among the most                prey on water-associated birds (especially
                        host-specific species, but several wetland            young chicks), and it would not be
                        birds are also restricted to areas                    desirable to place predator roosts in a
                        dominated by specific plants. Additional              marsh used by clapper rails.
                        linkages between vascular plants and
                        animals, especially those in the soils and                Quantitative         sampling         fo r
                        and root zone (rhizosphere), still await              vascular plant species composi-
                        discovery.                                            tion. A long-term sampling program at
                                                                              Tijuana Estuary (1979-present) provides


                                                                       52





                    Sampling methods and comparative data from natural wetlands


                  the most extensive data set for salt marsh         because of their trailing and branched
                  species composition.          Comparable           habit and the difficulty of deciding what
                  sampling       methods        are      thus        constitutes an individual.       For this
                                                                                                   -ed. Because
                  recommended. The sampling program                  reason, cover data are prefer7
                  records species presence (for frequency            the sum of cover of individual species
                  of occurrence data), visual cover                  may exceed 100%, a separate visual
                  estimates for all species, and more                estimate must be made for total vegetative
                  intensive analysis of cordgrass, which is          cover.
                  often a restoration target species. The
                  most important feature for comparing                   Six cover classes have been used in
                  occurrence data is quadrat size; data from         the Tijuana Estuary monitoring program.
                  different size quadrats are not                    Frequency histograms of cover classes
                  comparable, as larger quadrats encounter           are readily compared with the
                  more species. Quarter-square meter                 Kolmogorov-Smirnov two-sample test.
                  quadrats are suitable for salt marsh               Mean cover can be estimated by using the
                  vegetation, because several individuals            midpoints of each cover class. Because
                  can be found within that area. Quadrat             of the imprecision involved in estimating
                  shape should also be held constant.                cover, differences of less than 25%
                  Circular quadrats were chosen for Tijuana          between two sites are not meaningful.
                  Estuary, because an initial objective was
                  to understand interspecific: interactions.
                  The species occurring together in a 0.25-              Cover              Midpoint of
                  m2circular quadrat have intermingling                  class              cover class
                  roots. Thus, data on species that occur                  >0-1%                   0.5%
                  together are useful in evaluating
                  interactions.       Additional useful                        1-5                 3.0
                  measurements are canopy height and data                    6-25                 18.5
                  on flowening and/or fruiting by species.                  26-50                 38.5
                                                                            51-75                 63.5
                     To determine species composition,                     76-100                 88.5
                  cover, and canopy heights, permanent
                  sampling locations (quadrats. along
                  transects) are established and marked for              Cover of vegetation is compared more
                  elevation. Thes6 are sampled in late               precisely by sampling canopy intercept
                  August or September for presence and               along the transect lines. The intercepts of
                  cover of each species and for heights of           each species and of bare space are
                  cordgrass stems, within 0.25 m2 circular           recorded within 4- or 5-m segments of
                  quadrats.                                          each transect line. The smallest unit of
                                                                     intercept recorded is 1 dm.      Lines are
                     Additional data are useful for                  placed along elevation contours, and the
                  cordgrass, which has a growth form that            meters of cover within 4-m segments of
                  allows easy measurement of culm. height.           the line are recorded to the nearest
                  In dense stands, 0.10 m2 quadrats are              decimeter. A simple comparison of man-
                  adequate to give reliable estimates of the         made and natural wetlands uses a
                  mean cordgrass growth. Heights are                 cumulative frequency histogram of the
                  summarized to provide total stem length            number of segments with 0, 0.1-1.0,
                  (sum of all heights, which is a good               1.1-2.0, 2.1-3.0, and 3.1-4.0 meters of
                  estimator of aboveground biomass),                 cordgrass cover (Figure 4.1, data from
                  average height, and density (number of             Swift 1988).        In the cumulative
                  stems).                                            histogram, the tally for the first cover
                                                                     class is recorded, then the tally for the
                     Other species are less amenable to              second class is added to the first, etc.,
                  height measurement or density counts,              until all tallies are included in the last
                                                                     point of the graph. From this summary


                                                               53





                         Sampling methods and comparative data from natural wetlands


                       of the data, it is clear that the man-made         marsh plants, based on Carpinteria Salt
                       marshes have far more area of zero or              Marsh. His cumulative list of salt marsh,
                       low cordgrass cover than the reference             brackish marsh, and transition to upland
                       wetland, Paradise Creek. The man-made              includes 38 species (Table 4.1)..
                       site that most closely approximates
                       cordgrass cover in the natural marsh is               The regional distribution of a subset
                       Nursery 1, which was in its third                  of these species is given in Table 4.2.
                       growing season at the time of Swift's              This regional comparison shows that
                       survey.                                            species richness relates to the degree of
                                                                          tidal flushing--wetlands with a long
                          Censuses of target species                      history of tidal flushing have most of
                       (desirable and undesirable) should be              these species.
                       made during the period of time when they
                       are most conspicuous. High marsh is
                       examined in April to locate and census
                       salt marsh bird's beak - patches
                       (Cordylanthus maritimus ssp. maritimus)
                       and associated (potential) host species.
                       The size of each patch is measured
                       (maximum diameter and the diameter
                       perpendicular to it), and counts of
                       individuals are made. Soil salinities at
                       10.- and 30-cm depth are measured at each
                       patch. If rainfall has been late, April may
                       be too soon to census patches, and
                       searches may need to be repeated later.

                          Patches of weedy species are located
                       and sampled in April, as many of the
                       exotics are short-lived annuals. The area
                       of weedy vegetation is measured as
                       above, and soil salinities recorded for 10-
                       and 30-cm depths.

                          An additional plant population to be
                       monitored more closely is the rare annual
                       goldfields, Lasthenia glabrata, which may
                       be found at the edges of seasonal pools or
                       salt pannes that impound rainfall. The
                       population at Los Pefiasquitos Lagoon                                        MG.   JIG
                       has been monitored for several years
                       (Nordby, SDSU, unpub. data), by
                       locating and measuring the size- of
                       patches, plus obtaining density estimates
                       using the nearest-neighbor method and b
                       direct counts of densities using 0.25 rn@
                       quadrats and 0. 10 m2 quadrats.

                                                                                   Salt marsh bird's beak
                                                                                  Cordylanthus maritimus
                          Reference data:        Tidal marsh                            ssp. maritimus
                       community composition: Ferren
                       (1985) gives the most complete list of salt


                                                                   54





                           Sampling methods and comparative data from natural wetlands


                       Figure 4.1 The cumulative percent of 4-m intervals with 0-to-4 meters of cordgrass
                       cover near Sweetwater Marsh, San Diego Bay in summer 1987. Each transect followed the
                       elevation of maximum cordgrass establishment. The Connector Marsh sites were graded
                       and opened to tidal flow in fall 1984 and planted with cordgrass in Jan.-Mar. 1985.
                       Nursery I was graded and planted in July-Nov.1983. Paradise Creek is a natural marsh
                       remnant just upstmam of the Connector Marsh.

                                                           Nine Sites in the Connector Marsh

                                                    100-
                                           0-0-

                                                      80-




                                                      60-
                                           Cr


                                           LL
                                                      40-
                                           >                                       k
                                           cc         20-                        Nursery 1
                                           E                                                        Paradise Creek

                                           0          0
                                                                  0         1        2         3         4
                                                Meters of Cover Within 4-m Interval



                       Table 4.1. Native plant species list for "estuarine wetlands" of the Carpinteria salt marsh
                       (from Ferren 1985). *=not seen by Ferren; possibly extirpated from this wetland.

                       Anemopsis californica                                   Hordewn depressm
                       Arthrocnemum (=Salicornia) subterndnale                 Hymenolobus procumbens
                       Aster subulatus var. ligulatus                          Isocom veneta var. vernonidides
                       Atriplex californica                                    Jawnea carnosa
                       A. lentiformis ssp. breweri                             *Juncus acutus var. sphaerocappus
                       A. patuld ssp. hastata                                  J. bufonius
                       A. watsond                                              Lasthenia glabrata ssp. coulteri
                       Baccharis douglasii                                     Limonium californicum
                       B. pilularis ssp. consanguinea                          Monanthochloe littoralis
                       *Carexpraegracifis                                      Salicornia iftinica
                       *Chenopodium macrospermum ssp.farinosum                 Scirpus californicus
                       C. strictum                                             S. maritimus
                       Cordylanthus nwritimus ssp. maritimus                   *S. pungens
                       Cressa trad1lensis ssp. vallicola                       Spergulww mcrotheca var mcrotheca
                       Cuscuta salina                                          S. mrina
                       Distichlis spicata ssp. spicata                         Suaeda calceoliformis
                       Euthanda occidentaUs                                    S. californica var. pubescens
                       Frankenia gran&folia ssp. gran&folia                    Triglochin concinna
                       Heliotropium curassavicum ssp. occulatum                Typha doiningensis


                                                                            55





                        Sampling methods and comparative data from natural wetlands



                    Table 4.2. Presence of selected native plants in southern California coastal salt marshes.
                    X=extant, based on literature or personal observations; *=reintroduced, long-term status
                    uncertain; #--recently declined from greater abundance. Bold type indicates fully tidal
                    systems (ocean inlets are rarely closed). [Please forward any new information for these
                    species lists to PERL.]

                    Species codes: Fp=Frankenia palmeri; Cm=Cordylanthus maritimus ssp. maritimus;
                    Bm=Batis maritima; Sb=Salicornia bigelovii; Sf=Spartinafoliosa; Lg=Lasthenia glabrata;
                    Tc=Triglochin concinnum; Aw=Atriplex watsonil; Lc=Limonium californicum, Ct=Cressa
                    .truxillensis; MI=Monanthochloe littoralis; Se=Suaeda esteroa; Cs=Cuscuta salina;
                    Ja=Juncus acutus; Sv=Salicornia virginica; Fg=Frankenia grandifolia; Ds=Distichlis
                    spicata.

                                                Fp   Bm     Sf    Tc    Lc   MI    Cs    Ss    Sv   Ds
                    Coastal Salt Marsh             Cm    Sb    Lg Aw       Ct   Se    Ja    JC    Fg

                    Sweetwater Marsh            x x    x x  x     x x   x x  x x   x  x  x x   x  x x      18
                    Tijuana Estuary                 X  X #  X X   X  X  X  X X 4   X  X  X  X  X  X X      18
                    Mugu Lagoon                     X  X X  X X   X X   X    X X   X  X  X X   X  X X      17
                    Anaheim Bay                     *  x x  x x   x x   X x  x x   x x   x x   x  x x      16
                    Upper Newport       Bay         X  X X  X     X  X  X    X X   X  X  X X   X  X X      16
                    Santa Margarita Estuary               x    x     x  X'X  x  x  x  x  x  x  x  x x      14
                    Bolsa Chica Wetland                x x  x        X  X X  X X      X  X  X  X  X X      14
                    Mission Bay Reserve                X  X X     X     X    X  X  X     X  X  X  X X      13
                    Carpinteria                     x          X  X  X  X  X X     X     X  X  X  X X      13
                    Goleta Slough                              x  x #   x  x x #   x     x x   x  x x      13
                    Los Pefiasquitos Lagoon                    X     X  X  X X  X  X  X  X  X  X  X X      13
                    San Dieguito Lagoon                        X        X  X X  X     X  X  X  X  X X      12
                    Batiquitos Lagoon                          x        x  x x        x  x  x  x  x x      10
                    Agua Hedionda Lagoon                                   x x  x  x  x  x  x  x  x x      10
                    Ballona Wedand                                         x             X  x  x  x x      6
                    San Elijo Lagoon                                       x             x  x  x  x x      6
                    Deveraux Lagoon                                        x       x        x  x  x x      6
                    Santa Clara R. Estuary                                 x          x  '  x  x  x x      6
                    San Luis R. Mouth                                                 x     x  x  x x      5
                    Las Flores Marsh                                                     x  x  x  x x      5
                    McGrath Lake                                                      x     x  x  x x      5
                    Malibu Creek                                                   x        x  x  x x      5
                    San Mateo Marsh                                                x           x  x x      4

















                                                                 56





                        Sampling methods and comparative data from natural wetlands


                        For a few salt marshes in southern              useful in showing transect- to- tran sect
                    California and northern Baja California,            variability in species abundance.
                    descriptions are available in the published             Species composition within salt
                    literature. See Ferren (1985) for data on           marshes is related to elevation, which in
                    Carpinteria Marsh, Onuf (1987) for                  turn indicates differences in inundation,
                    Mugu Lagoon, Schreiber (1981) for                   salinity, and a host of other environ-
                    Ballona Wetland, Vogl (1966) for Upper              mental factors. The following data were
                    Newport Bay; Zedler and Beare (1986)                obtained in the September 1988 annual
                    for San Diego River Marsh, Zedler                   census of the Tijuana Estuary salt marsh,
                    (1977) for Tijuana Estuary, and                     including 207 quadrats between 5-18 dm
                    Neuenschwander et al. (1979) for San                MSL (approximately 1.5-6 ft MSL, or
                    Quintin Bay, Baja California, Broader               4.5-9 ft NGVD). Since most of the
                    discussions of the California salt marshes          quadrats occur on the marsh plain, these
                    appear in Macdonald and Barbour (1974)              data characterize the lower- and middle-
                    and Macdonald (1977, 1988). Data for                marsh habitats best. The % frequencies
                    additional wetlands appear in less widely-          are provided by elevation for all species
                    circulated reports.     The US Fish and             that occurred in more than 10% of the
                    Wildlife Service has provided preliminary           quadrats.     Occurrences of the less
                    results for Santa Margarita Estuary                 common species are listed. Cover (mean
                    (Hollis et al. 1988), and the Topanga-Las           %, based on cover classes) is for
                    Virgenes Resource Conservation District             quadrats of occurrence only (excluding
                    has released a baseline survey for Malibu           O's), so quadrat n is not constant.
                    Lagoon (Manion and Dillingham 1989).                Elevation class 5-6 ranges from 5.0 to
                    Additional wetlands under study by                  6.9 dm, etc.
                    PERL/SDSU researchers include Ballona
                    Wetland, Los Pefiasquitos Lagoon, and                   The summary data for occurrence and
                    Sweetwater River Wetland Complex.                   cover indicate different attributes of these
                    General descriptions of many of the                 species.      Pickleweed (Salicornia
                    region's coastal wetlands have been                 virginica) is the most abundant, and it
                    published by the California Dept. of Fish           generally has high cover. Saltwort (Batis
                    and Game, as part of a Wetland                      maritima) is widespread at lower
                    Resources Inventory, carried out in the             elevations, but never has high cover.
                    1960's and 70's.                                    Shoregrass (Monanthochloe littoralis) is
                                                                        restricted to the high marsh, but this mat-
                        The detailed studies of marsh                   forming grass generally has high cover.
                    vegetation are useful in showing how                From the 1974 distributions at Tijuana
                    different species respond to reductions in          Estuary, we have identified the elevation
                    tidal flushing. The composition of Santa            where percent occurrences are greatest
                    Margarita Estuary (Table 4.3), which is             and indicated the average of the maximum
                    often closed to tidal flow in summer, is in         heights these species achieved within all
                    strong contrast with the species-rich               quadrats of occurrence (Table 4.5).
                    marsh at Tijuana Estuary (Table 4.4).
                    There are fewer species overall, and                    Upper marsh and transition habitats
                    Salicornia virginica has very high                  have not been studied extensively. There
                    dominance. Tijuana Estuary, in turn, lost           are few areas of undisturbed transition-to-
                    some of its richness during the 1984                upland habitat . At Tijuana Estuary, one
                    nontidal period of 8 months. At Santa               gradual slope adjacent to the salt marsh
                    Margarita Estuary, three pickleweed                 was sampled for species composition and
                    habitat types were distin-guished by                results combined with the 1974 census
                    Hollis et al. (1988), but the tabular data          data. The data indicate in general how far
                    show considerable overlap in species                upslope many of the marsh species go
                    composition among sites that appeared               (Table 4.6).
                    different to the eye. The results are



                                                                  57





                         Sampling methods and comparative data from natural wetlands


                       Table 4.3. Salt marsh vegetation at       Santa Margarita Estuary from Hollis et al. (1988).
                       Data in each column are meters of cover from one 100-m-long transect. Vegetation types
                       are as named by Hollis et al. (1988). Species with less than 1% cover are indicated with an
                       X.


                                                      Salicornial        Salicornial          Salicornial          Maritime
                                                      Frankenia            Distichlis           U                  Scrub
                                                                                                  @pland

                       Bare ground                        1    0       21    30 26            9    0     6         7   22
                       Mean Height (cm)                 47   41        28 23        38       24   34     31     55 124

                       Salicornia virginica             80   54        58    28     60        5    2     27            11
                       Jaumea carnosa                                                                    4                4
                       Suaeda esteroa                                                                    3
                       Frankenia grandifolia            18   23                       x            x     16
                       Distichlis spicata                    21        21    42     14                   35               x
                       A triplex watsonii                      x
                       Salicornia subterminalis                                            54 24
                       Cressa truxillensis                                                    x    2     4
                       Atriplexpatuld                                                                    3
                       Croton californicus                                                                         3
                       Isocoma venetus                                                             x             16    36
                       Opuntia sp.                                                                                 7
                       Heliotropium curassavicum                                                         x
                       Baccharus glutinosa                                                                             13
                       Ambrosia chamissonis                                                              x
                       Weedy exotics                           x                           32 69         4       66    13


                       Table 4.4. Species Composition of the Tijuana Estuary salt marsh, 1988.
                                                                                                         Mean
                       Elevation class (dm)              5-6       7-8      9-10    11-12     13-18      overall   Cover

                       Quadrat n                          43       101       36         14        13       207     Varies

                       Species and Frequency              %        %         %          %         %          %.        %

                       Spartinafoliosa                    74       39        22          0         0       38         49
                       Batis maritima                     33       63        42          0         0       45         20
                       Jaumea carnosa                     12       32          8         0         0       19         16
                       Salicornia virginica               86      -96        86         39         0       82         52
                       Frankenia grani*folia              9        34        44         43       _@L4      32         22
                       Monanthochloe littoralis           0          6       44         93        46       20         47
                       Salicornia subterminalis           0          0       14         64        85       12         44
                       Triglochin concinnum                                                                  7        10
                       Distichlis spicara                                                                    7        17
                       Limonium californicum                                                                 2         6
                       Cressa traxillensis                                                                   5        10
                       Additional species present in the marsh but not encountered in the 1988 sample
                       Salicornia bigelovii
                       Suaeda esteroa
                       Atriplex watsonii
                       Cordylanthus maritimus ssp. maritimus



                                                                     58





                         Sampling methods and comparative data from natural wetlands


                      Table 4.5. Summary data for peak firquency of occurrence and the average of maximum
                      heights observed at Tijuana Estuary.

                                                                       Elevation of              Ave. max.
                                                                     peak frequency                 height
                                        Species                        (dm MSL)                  in cm (s.e.)

                                Spartinafoliosa                               3                     60   (10)
                                Salicornia bigelovii                          6                     38   (10)
                                Bafis mafitbw                                 6                     24    (5)
                                Salicornia virginica                          5                     36    (9)
                                Jawnea carnosa                                7                     21    (4)
                                Suaeda esteroa                                9                     29    (8)
                                Frankenia granXfoha                          10                     23    (6)
                                Monanthochloe littoralis                     .11                    24    (6)
                                Distichlis spicata                            9                     25    (6)
                                Linwniwn californicwn                        10                     no data
                                Triglochin maritima                           7                     no data
                                Salicornia subterrdnalis                     11                     31    (6)
                                Cuscuta salina                                9                     no data
                                Cressa truxillensis                          10                     no data






                      Table 4.6. Elevation ranges of salt marsh species. Occurrences are for 2-dm elevation
                      classes, combining the 1974 survey and the analysis of Site 1. Class 3 indicates 3.0-4.9
                      dm NGVD or 1.0-1.6 ft NGVD. Metric units are useful because the vegetation responds
                      to elevation differences as small as 1 dm (10 cm).

                      Elevation class (relative to NGVD)
                            decimeters                3   5   7    9 11 13 15 17 19 21 23 25 27 29 31
                           feet                       1.0     2.3      3.6     4.9      6.2     7.5      8.9   10.0

                      Spartinafoliosa                 x-  x
                      Batis rwritirm                  x   x   x
                      Salicornia bigelovii            X   x   x    X
                      Jaumea carnosa                  x   X   X    x
                      Suaeda esteroa                  x   x   x    x
                      Salicornia virginica            x   x   x    X   x   X x x X x
                      Frankenia grandifolia           x   x   x    x   X   x   x    x   x x x x
                      Monanthochloe liuoralis         x   x   x    x   x   x   x    x   x   x
                      Distichlis spicata                  x   x    x   x   X   X x      x   x x x x x X
                      Triglochin mantirw                  x   x
                      Cuscuta salina                      x   x    x
                      Limonium californicwn               x   x    x   1
                      Salicornia subterminalis            x   x    X   x   x   x x
                      Atriplex watsonii                       x    x   x   x   x x      x
                      Cressa truxillensis                     x    x   x   X   X x      x x x X X





                                                                       59





                      Sampling methods and comparative data from natural wetlands


                        No salt marsh is stable; composition            production of the region's dominant
                    changes annually. From the long-term                species (Onuf 1987).
                    monitoring program, we know that cord-
                    grass responds to varying environmental                 By comparing data from tagged
                    conditions (Zedler 1983, Zedler and                 branches with harvest data, Onuf deter-
                    Nordby 1986); it declined with hyper-               mined that large amounts of leaf and stem
                    saline drought (1984) and recovered                 material are lost from plants between
                    slowly thereafter. Annual pickleweed                harvests. Thus, estimates of NAPP from
                    (Salicornia bigelovii), which was                   repeated harvests were too low by a fac-
                    extremely abundant at the same elevations           tor of 2.3 for Salicornia virginica, 3.7 for
                    as saltwort in 1974 (Zedler 1977), was              Jawnea carnosa, 1.89 for Limonium cali-
                    nearly extirpated during the 1984                   fornicum, and 2.9 for Batis maritima
                    drought; it may persist in one small patch.         (Onuf 1987, p. 7 1):. Additional errors are
                    Sea blite (Suaeda esteroa) also declined in         no doubt present due to the high hetero-
                    1984, but persists more widely, although            geneity of aboveground biomass that is
                    only as scattered individuals. In the               present in the region's species-rich
                    1984-1988 record, three species have                marshes. Unlike monotypic Spartina
                    been consistently common (S. virginica,             alterniflora marshes of the Atlantic and
                    B. maritima, F. grandifolia), 2 have not            Gulf of Mexico Coasts, a quarter-square
                    yet recovered from post-1984 declines Q.            meter of southern California marsh vege-
                    carnosa, T. concinnum), and 4 species               tation may include 8 or 10 different
                    have been consistently uncommon (M.                 species. Thus, obtaining representative
                    littoralis, S. subterminalis, D. spicata, L.        samples of the biomass of individual
                    californicum). These latter four species            species is nearly impossible. Combining
                    are not rare at Tijuana Estuary; their low          biomass of all species for a total NAPP
                    frequencies of occurrence simply reflect            estimate is not recommended, because
                    the low numbers of quadrats sampled at              individual species reach peak biomass at
                    their "preferred" elevations.           The         different times; thus such harvest data
                    strongest differences are seen by                   would further underestimate productivity.
                    comparing the 1974 samples with those               In common with harvest studies in all
                    of 1988 (Table 4.7).                                regions and habitat types, net productivity
                                                                        estimates based on standing crops do not
                       Even if composition changes little, the          take into account losses due to herbivory
                    height and vigor of plants can be highly            between harvests.
                    variable fi-om year to year. The dynamics
                    of Spartina foliosa and Salicornia vir-                Earlier studies (Winfield 1990, Zedler
                    ginica have been studied in detail and              et al. 1980, Eilers 198 1) erred in assum-
                    results published elsewhere (Zedler 1983,           ing that southern California harvest data
                    Zedler et al. 1986). Such information               could provide accurate estimates of salt
                    indicates that single samples of the vege-          marsh vascular plant productivity. Their
                    tation do not fully characterize its                data are best used as descriptions of the
                    condition.                                          aboveground standing crop. Eilers' har-
                                                                        vest data for 1977-78 have been
                                                                        reanalyzed for that purpose; sampling
                                                                        stations for the entire marsh have been
                       Biomass and net aerial primary                   pooled, and data for all species com-
                    productivity (NAPP) of vascular                     bined. The results for live and dead
                    plants.     Harvesting vegetation to                biomass (Figures 4.2-4.3) show that
                    estimate standing crops or primary                  biomass accumulates in the absence of
                    productivity is not recommended for                 tidal flushing (i.e., in Los Pefiasquitos
                    southern California coastal marshes. The            Lagoon).
                    harvest method is too destructive for our
                    remnant wetlands. Furthermore, the
                    standing crops grossly underestimate


                                                                 60





                  Sampling methods and comparative data from natural wetlands

                Table 4.7. Frequency of occurrence (% of quarter-square-meter quadrats sampled)
                at Tijuana Estuary in 1974 and 1988, comparing different sampling locations, but
                using the same dm elevation classes (6            6.0-6.9 dm. NGVD). The larger %
                ftequencies are in bold.

                Elevation class (dm)             Year

                    n                            1974         113     95      35      30      35
                    n                            1988         37      77      24      25      11


                Occurrence

                    Spartinafoliosa              1974.        24       0       0       0       0
                                                 1988         78      48       8      32       0

                    Bads ntafifi?w               1974         86      71      31       0       0
                                                 1988         30      61      71      44      36

                    Salicornia bigelovii         1974         90      83      46      17      14
                                                 1988          0       0       0       0       0

                    Jawnea carnosa               1974         42      88      60      53      51
                                                 1988         14      31      33      12       0

                    Suaeda esteroa               1974         26      43      63      63      34
                                                 1988          0       0       0       0       0

                    Salicornia virginica         1974         69      66      80      70      46
                                                 1988         86      96      96     100      54

                    Triglochin concinnwn         1974          6      12       3      10       0
                                                 1988          5      12       8       0       0

                    Frankenia grandifolia        1974         23      54      77      87      91
                                                 1988         11      30      46      40      54

                    Limoniwn californicwn        1974          7      12      11      10      20
                                                 1988          0       1       0       8       0

                    Distichlis spicata           1974          2       9      43      23       0
                                                 1988          0       4       4       4       9

                    Salicornia subtenninalis     1974          6       6      29      30      69
                                                 1988          0       0       0       0      46

                    Monanthochloe Huoralis       1974         19      32      63      90      97
                                                 1988          0       3      17      36      64

                    Cressa truxillensis          1974          0       0       0       0       0
                                                 1988          0       0       0       8      27







                                                               61





                         Sampling methods and comparative data from natural wetlands



                       Figure 4.2. Summary of live material harvested by Eilers (1981). Data are means L+1
                       s.e.) obtained from 0. 10 m2 rectangular quadrats. LPL-- Los Pefiasquitos Lagoon, n=21
                       stations; SRE= Sweetwater River Estuary, n=3   I stations; UNB= Upper Newport Beach,
                       n=25 stations.





                                   1750-
                                                  LPL
                            >  -,  1500-
                               04
                               E   1250-

                                   1000-
                            0
                            h-                    SFE
                            CD ca    750-
                            4) E
                            >  0     500-
                            0  -
                                                  UNB
                                    250


                                      0
                                                  Nov       Jan     Mar      May       Jul
                                                            Month 0 977-78)





                       Figure 4.3. Summary of dead material harvested by Eilers (1981). Data are explained in
                       Figure 4.2.



                                  2000-
                            001%
                            C*41  1750-                     LPL
                            E
                            C"    1500-
                            U)    1250-
                            U)
                            0%
                            E     1000-
                            0
                                   750-                    SFE

                            V      500-
                            Cto
                            4)
                                   250-                   UNB
                                      0-                             @ar       May
                                                  Nov       Jan                           Jul
                                                  LPL











                                                  UNB

























                                                          Month (1977-78)


                                                                 62





                     Sampling methods and comparative data from natural wetlands


                                                                         creeks, especially where tidal flushing is
                   The large difference in the amount of                 minimal (Rudnicki 1986, Fong 1986).
                   dead biomass at nontidal LPL suggests                 Thick mats of filamentous blue-green
                   that tidal flushing leads to faster decom-            algae and diatoms grow on the moist
                   position and/or export, both of which are             intertidal soils of the salt marsh and are
                   consistent with the findings of Winfield              especially productive in summer (Zedler
                   (1980). Additional historic data on                   1980,1982b).
                   standing crops appear in Winfield (1980)
                   for Tijuana Estuary and in Zedler et al.                 Estimating algal productivity rates is
                   (1980) for Tijuana Estuary, Los                       most easily accomplished by measuring
                   Peftasquitos Lagoon, and San Diego                    the amount of oxygen evolved by fronds
                   River Marsh.                                          or mats placed in aquatic chambers (e.g.,
                                                                         as carried out in the field by Zedler
                       There is a method for measuring vas-              1980). The oxygen concentration is mea-
                   cular plant productivity using individual             sured initially and after about an hour's
                   leaves or branches and assessing carbon               incubation time. Comparison of changes
                   dioxide uptake over short intervals of                in light and dark chambers yields esti-
                   time (minutes). Portable systems are                  mates of gross primary productivity.
                   available (ca. $15,000) for measuring                 These short-term rates can then be used to
                   photosynthesis using infrared gas analy-              estimate longer-term contributions of
                   sis to indicate changing concentrations of            algae by relating gross photosynthetic
                   carbon dioxide in chambers that enclose               rates to light regimes. The methods pro-
                   intact leaves. However, photosynthetic                vide valuable comparisons of different
                   rates for small portions of the plant must            algal types and different habitats, but sev-
                   be combined with estimates of total leaf              eral errors develop when calculations of
                   area to obtain net productivity rates for an          annual productivity are attempted (Zedler
                   area of marsh. Thus, some measure of                  1980). In addition, sampling is. very
                   biomass is still needed, along with fre-              destructive, especially if one attempts to
                   quent measurements to account for sea-                characterize a large number of habitats.
                   sonal changes in rates and regressions to             Sampling must be frequent, as algal
                   determine how rates vary with daily                   biomass and photosynthetic rates differ
                   inundation and temperature. Such mea-                 from week to week (with spring- and
                   sures are best used to compare functional             neap-tide inundation regimes), and a large
                   differences of different plants or habitats           number of replicates (for both light and
                   at single points in time.                             dark chambers) is needed to obtain
                                                                         reliable results.
                       In our opinion, it is not practicable to
                   measure vascular plant productivity.                     Results for Tijuana Estuary (Zedler
                   While various methods can be employed,                1980) for a year of good tidal flushing
                   they are too destructive and do not yield             (1977) indicated that algal mats beneath
                   data of sufficient accuracy to justify the            the marsh canopy were highly produc-
                   damages to the site. Data on cover and                tive, compared to Atlantic Coast wet-
                   height are more appropriate.                          lands, where taller, denser vascular plant
                                                                         canopies are present. While good data
                       Algal productivity. Measure-                      relating productivity rates to algal
                   ments of algal productivity are likewise              biomass or chlorophyll content are lack-
                   problematical. Yet this component is                  ing, it is conservative to assume that
                   probably very important to the food base,             where algal mats are thick and
                   not only because of high growth rates,                widespread, they will make an important
                   but also because of high digestibility                contribution to wetland primary
                   (Zedler 1980, 1982a). Several kinds of                productivity.
                   algae contribute to wetland productivity.
                   Phytoplankton and macroalgal mats                        To provide a general characterization
                   become abundant in channels and tidal                 of potential algal productivity, we


                                                                  63





                        Sampling methods and comparative data from natural wetlands


                      recommend that the presence and general            submerged macrophytes (primarily
                      abundance be noted on at least a quarterly         macroalgae) having the highest per-area
                      basis. Dominant r                                  rates (but covering a small area) and
                                         ypes of algae should be
                      indicated, using the following categories:         phytoplankton having the lowest per-area
                      Floating macroalgal mats (Enteromorpha,            and whole-system productivity. This
                      Ulva);      green epibenthic mats                  generalization is consistent with results
                      (Enteromorpha); blue-green epibenthic              from the -salt marsh at Tijuana Estuary,
                      mats, and diatom films. There is no easy           where benthic algal mats appear to be as
                      way to obtain accurate estimates of algal          important to ecosystem productivity as
                      abundance. Cover estimates (classes as             are the vascular plants (Zedler 1980).
                      for vascular plants) can be made within
                      specified areas, e.g., 1-5 m2 sampling
                      stations that follow the shape of channels
                      or creeks; square-meter segments of the
                      salt marsh, etc.

                        I The overall primary produc-
                      tivity function. Although primary
                      productivity is a basic ecosystem
                      function, there are major problems and
                      errors in measuring productivity rates and
                      calculating the contributions of different
                      producer components for different wet-
                      land areas are great. A further concern is
                      the destructiveness of the sampling.
                      Thus, we recommend that productivity
                      studies be considered in          research
                      programs, rather than as monitoring
                      objectives.

                          Given the unreliability of harvest data
                      for estimating NAPP, we are left with
                      only general remarks concerning the pri-
                      mary productivity of southern California
                      coastal wetlands. Onuf (1987) estimated
                      productivity of phytoplankton, benthic
                      microflora, submerged macrophytes and
                      emergent macrophytes for Mugu Lagoon,
                      but only after offering several precautions
                      about the data (ibid., p. 72): "The main
                      caveat about the productivity estimates for
                      the salt marsh vascular plants is the
                      uncertainty arising from the measurement
                      techniques and calculations. The monthly
                      estimates are imprecise because of the
                      high spatial heterogeneity of the marsh.
                      These errors are propagated in the math-
                      ematical manipulations used to generate
                      the annual estimates." His general results
                      for the eastern arm of Mugu Lagoon                               Nest of the
                      suggest that the benthic microflora, and                 light-footed clapper rail
                      emergent macrophytes are both principal                Rallus longirostris levipes
                      contributors to wetland productivity, with



                                                                   64





                  Sampling methods and comparative data from natural wetlands


                                                                    (and occasional tiger beetle burrows)
                      5. Marsh insects:                             suggests great importance.
                Pollinators, predators,                                 These and other functions of the
                              and prey                              hundreds of coastal wetland insects merit
                                                                    assessment of the insect fauna. We
                                                                    recommend general surveys of selected
                    Objectives. The insects of south-               habitat types to characterize the insect
                ern California are responsible for several          communities along with specific censuses
                important salt marsh functions, including           of sensitive species (globose dune beetle,
                pollination, seed dispersal, aerating soils,        wandering skipper, and tiger beetles).
                controlling herbivorous insects, and pro-
                viding food for birds, small mammals,                   Community sampling methods.
                and other carnivores.                               Pan traps are used in nontidal areas to
                                                                    trap crawling insects and many flying
                    While many of the plants are wind               insects. The method can be used in tidal
                pollinated, there are several species that          areas during neap tides, if traps are
                rely on insects for pollination and seed            revisited before a high tide inundates
                production. The endangered salt marsh               them. Replicate traps (6-10 per site) are
                bird's beak (Cordylanthus maritimus ssp.            randomly placed within areas of relatively
                maritimus) and the regionally rare                  uniform plant canopy. Sampling in the
                goldfields (Lasthenia glabrata) are                 warmer parts of the year produces more
                important examples. Members of the                  insects and different species than
                Coleoptera, Diptera, Hymenoptera, and               sampling in cool seasons, according to
                Lepidoptera are important in pollination.           K. Williams and K. Johnson (SDSU,
                Pollinators link the upper salt marsh to            pers. comm.).       At Tijuana Estuary,
                the adjacent coastal scrub-dominated                September samples had abundant beetles
                upland, where alternative nectar-                   and ants, while January samples were
                producing plants are found. Thus, a fully           dominated by flies.         Early spring
                functional marsh has nearby transitional            sampling is suitable for many butterfly
                and upland habitats that maintain an                species; pollinators would be best
                abundance of pollinators.                           sampled in May; late summer is
                    The herbivore-control function was              appropriate for tiger beetles.
                shown to be critical at the dredge spoil                The pan traps are small cake pans
                island in south San Diego Bay. Four                 (approx. 23x33x5 cm deep) painted
                years after cordgrass was planted, a                yellow on the inside and placed in a
                native scale insect (Heliaspis spartina)            shallow excavation under the plant
                reached epidemic densities and severely             canopy, so that the edge of the pan is
                reduced the@ aboveground biomass of                 flush with the ground and vegetation.
                cordgrass.     Kathy Williams (SDSU,                Enough propylene glycol (anti-freeze) is
                unpub. data) determined that the native             poured into each pan so that the bottom is
                predators (e.g., the beetle, Coleomegilla)          covered to a depth of about 1 cm. Insects
                were lacking, and an experimental control           fall into the pans and cannot escape.
                program involving the release of the                After about 48 hours, the traps are
                predator is now underway.                           strained through a sieve and the insects
                                                                    are collected in 70% ethanol in labeled
                    Burrowing insects are an integral part          jars. These can be stored for later sorting
                of the soils of salt pannes and higher              and identification.
                intertidal marsh areas. While the role of
                insects in soil aeration and organic matter             Sweep sampling is necessary to
                incorporation remains unquantified, the             characterize insects in tidal areas and to
                great abundance of rove beetle burrows              capture more of the flying insects.
                                                                    Standard butterfly nets are used for this


                                                              65





                           Sampling methods and comparative data from natural wetlands


                        sampling. Uniform numbers of sweeps                     at Tijuana Estuary from areas of
                        through vegetation are made along                       cordgrass (Spartina foliosa), tidal and
                        transects of similar length. To sample a                nontidal pickleweed (Salicornia
                        marsh area dominated by Spartina                        virginica), dune, and transition to upland
                        foliosa, Williams et al. (unpub. report)                (dominated by flat-topped buckwheat,
                        used 10 transects of 20 m length to                     Eriogonwn fasciculatum). Six orders of
                        sample, with 30 sweeps made along each                  insects comprised the bulk of the insects
                        transect. Transects were parallel and 10                sampled in September, January, and
                        in apart.                                               April: Coleoptera, Collembola, Diptera,
                                                                                Homoptera, Hymenoptera, and
                             Visual surveys are suitable for tiger              Lepidoptera (Table 5. 1). In all, 22 orders
                        beetles in mudflat, sandy beach, and salt               of arthropods were identified.
                        panne habitats. The numbers seen while
                        walking transects of known length are                      Patterns of spatial and temporal
                        recorded. Dune beetles may need to be                   variability were found, with upland and
                        seived from sand near and under dune                    transition habitats having the largest
                        vegetation. Chris Nagano (US FWS                        numbers of orders (10-11) present and
                        Endangered Species Office, Sacramento)                  winter generally having the fewest orders
                        indicates that mark-recapture techniques                represented (:@7, except for the transition
                        can be used with these species. His                     habitat, which had 11 orders). Overall,
                        advice should be sought for work with all               the habitats dominated by cordgrass and
                        rare and sensitive insects.                             pickleweed had the fewest orders (2-8)
                                                                                represented. The summaries of arthropod
                             Neither the pan trap     nor the sweep             numbers (Figure 5.1-5.3) indicate
                        methods provide information that can be                 substantial differences between habitat
                        used to estimate densities, because of the              types and suggest interactions with
                        potential for pan or net avoidance. The                 season. Ants were primarily in the
                        counts of insects are best interpreted as               upland, in September; leafhoppers and
                        relative densities for the habitats and                 planthoppers were most abundant in
                        times sampled. Such data are valuable                   Sparrina in January, but not in April; and
                        indicators of general abundance;                        flies were particularly numerous in
                        information on the abundance or absence                 Salicornia.
                        of certain functional groups (e.g.,
                        pollinators, predators) and of sensitive                   Williams and several students are
                        species is essential for characterizing                 continuing to investigate patterns of insect
                        wetland ecosystems.                                     abundance and distribution at local
                                                                                wetlands, and a better understanding of
                             Species identification is the biggest              both structural and functional aspects of
                        problem with characterizing the insect                  the arthropod community should be
                        community, and it may not be possible to                available in the next few years.
                        identify many taxa beyond the family                    Additional species lists, but no
                        level. However, this is often very useful               quantitative data, are available for Ballona
                        for examining functional groups. Even                   Wetland, north of Los Angeles airport
                        general information on size and habit                   (Nagano, in Schreiber 1981).
                        (flying or crawling) will be helpful in
                        characterizing insects as potential food
                        items for consumers such as Belding's
                        Savannah sparrows. Species of special
                        concern, such as the tiger beetles,
                        globose dune beetle, and wandering
                        skipper, need to be identified to species.

                             Reference data on coastal insects
                        (Williams et al. 1989) have been obtained


                                                                         66





                    Sampling methods and comparative data from natural wetlands


                    Table 5.1. Orders of Arthropoda at Tijuana Estuary, in order of decreasing abundance in
                    pan traps (from Williams, et al., unpub. report). In all, 17,627 individuals were captured.

                                        Order                  Common name                    % of total

                                 Diptera                 flies                                    28.1
                                 Hymenoptera             bees, wasps                              10.4
                                                         Formicidae (ants)                        21.9
                                 Homoptera,              lea&oppers, planthoppers                 19.7
                                 Coleoptera              beetles                                    6.4
                                 Lepidoptera             butterflies, moths                         1.6
                                 Collembola              springtails                                1.1
                                 Araneida                spiders                                    0.8
                                 Isopods                 pillbugs                                   0.6
                                 Amphipods               amphipods                                  0.5
                                 Dermaptera              earwigs                                    0.4
                                 Heteroptera             true bugs                                  0.4
                                 Orthoptera,             grasshoppers, crickets                     0.4
                                 Acarina                 mites, ticks                               0.3
                                 Solpugida               wind scorpions                             0.1
                                 Thysanoptera,           thrips                                     0.1
                                 Tricoptera              caddisflies                                0.1
                                 Odonata                 dragorx/damselflies                      <0. 1
                                 Thysanura               silverfish                               <0. 1
                                 Isoptera                termite                                  <0. I
                                 Neuroptera              lacewing                                 <0. 1
                                 Phalangida,             harvestmen                               <0. I
                                 Psocoptera              psocids, book lice                       <0. 1




                    Figure 5.1. Relative abundance of selected orders among five habitats sampled at
                    Tijuana Estuary during September 1988 (from Williams et al., unpub. report).
                          30-        Distribution of Arthropods                            Sept. 1988

                                           Araneida
                                           Coleoptera
                                           Collernbola
                          20-              Diptera
                                   0       Homoptera
                      0
                                           Hymenoptera
                                           Hym:Formicidae
                      0                    Lepidoptera
                      --'0 to-             Others
                      0







                           0
                                    Spartina        Salicornia            Dune            Transition         Upland



                                                                         67





                      Sampling methods and comparative data from natural wetlands



                      Figure 5.2. Relative abundance of selected orders among five habitats sampled at
                      Tijuana Estuary during January 1989 (from Williams et al., unpub. report).

                          30-        Distribution of Arthropods                      Jan. 1989
                                                                                                       Araneida
                                                                                                       Coleoptera
                                                                                                       Collembola
                                                                                                       Diptera
                          20-                                                                          Homoptera
                      0                                                                                Hyrnenoptera
                                                                                                       Hym:Formicidae
                      0                                                                                Lepidoptera
                                                                                                 E3    Others
                          10-
                           0                                                           MAE                 -' HIM
                                   Spartina         Salicornia           Dune           Transition          Upland







                      Figure 5.3. Relative abundance of selected Arthropod orders among five habitats
                      sampled at Tijuana Estuary during April 1989 (from Williams et al., unpUb. report).

                                   Distribution of Arthropods                       April 1989
                          30-

                                                                                                Araneida
                                                                                                Coleoptera
                                                                                                Collembola
                          20-                                                                   Diptera
                                                                                            0   Hornoptera
                       0                                                                        Hyrnenoptera
                                                                                                Hym: Formicidae
                       0                                                                    El  Lepidoptera
                           10                                                               0   Others



                                                                                       IL r7i
                           0--                                          L-Mal
                                  Spartina        Salicornia        Dune          Transition       Upland




                                                                    68





                      Sampling methods and comparative data from natural wetlands


                                                                         samples needed per station varies; more
                                6. Aquatic                               samples are needed to characterize areas
                                                                         that are highly heterogeneous. A species-
                      invertebrates:                Food                 area curve (cumulative number of species
                             chain support                               encountered, plotted against cumulative
                                                                         area sampled, cf. Figure 6.1) for each
                                                                         station will indicate whether or not the
                        Objectives. Benthic macroinverte-                first few samples have encountered most
                    brates are good indicators of habitat                of the species present.
                    quality and food chain support. Fully
                    tidal wetlands support a large number of                 The method proposed will capture
                    benthic invertebrate species, many of                clams and ghost shrimp; worms and
                    which have long life spans and grow to               some insects will also be obtained. Sieve
                    large size. In areas subjected to frequent           size is the most important factor to keep
                    disturbances, such as dredging and                   constant, and a 1-mm screen is required
                    excess freshwater inflows, bivalves may              to compare results with reference data
                    persist, but the species composition will            sets. Samples are seived and all obvious
                    shift from longer-lived to annual species.           animals identified in the field and
                    In the absence of good tidal flushing,               released. Less obvious animals are taken
                    clams and ghost shrimp become replaced               to the laboratory for identification.
                    by species of polychaetes that are tolerant          Polychaetes are very difficult to identify,
                    of stagnant water and other environmental            but representatives can be preserved for
                    extremes.     Polychaetes also invade                future reference.       The numbers of
                    rapidly following catastrophic events,               individuals by species should be
                    such as rapid salinity reduction (Nordby,            compared temporally and between
                    SDSU, pers. comm.).                                  stations. Additional information on size
                                                                         of clams for common species is very
                       Methods.. Two methods are             rec-        useful; even the simple measure of the
                    ommended for sampling aquatic inverte-               largest individual of each species at each
                    brates: sediment cores to assess benthic             station or notes concerning the relative
                    burrowing forms and litterbag traps for              abundance of large and small individuals
                    mobile invertebrates on the marsh surface            would help to document large changes in
                    (small crabs, amphipods, and insect                  population structure. Further details
                    larvae). In addition, direct counts of               (size-frequency distributions) would help
                    snails and of crab burrows are sometimes             describe the food base.
                    used on mudflats. Each is discussed with
                    reference data below. - Benthic macro-                   Reference data for. benthic
                    invertebrates sampling stations are best             cores. Our data from Tijuana Estuary
                    located near the fish sampling sites (see            (Table 6.1-6.3) are useful for describing
                    below), where channel morphometry                    a community under disturbance stress,
                    (width, depth, bank characteristics) is              rather than a restoration target. Historical
                    described.                                           data from Tijuana Estuary and Mugu
                                                                         Lagoon are used to indicate the "healthy"
                       Sediment cores. Benthic macroin-                  benthic community that should be
                    vertebrates are collected using a stainless          expected for sites without dredging,
                    steel cylindrical "clam gun" 45 cm in                sewage inflows, excessive street
                    length and 15 cm in diameter. This                   drainage, or wastewater discharges.
                    device is pressed into the sediment to a
                    depth of 20 cm. Replicate cores are taken
                    within a sampling station. A convenient
                    size station is a circular area of about 2 rn
                    in diameter. Usually, five cores per
                    station will include all of the species
                    present (Figure 6. 1). The number of


                                                                  69





                     Sampling methods and comparative data from natural wetlands


                   Figure 6.1. Cumulative number of benthic invertebrate species for stations in the
                   southern and northem arms of Tijuana Estuary. Each sample was the sediment
                   collected with a clam gun and then sieved with a 1-mm screen.


                              30-

                                         North arm, station 5
                         Z
                         I

                         CL   20-


                         0                               South arm, station1


                              10-
                         E
                         3
                         z



                               0
                                 0        1       2       3        4       5        6
                                                      Sample




























                                                          70





                      Sampling methods and comparative data from natural wetlands


                    Table 6.1 Mean number of macroinvertebrate species/core sample in the north and south
                    channels of Tijuana Estuary (and s.e.). Data are for all species, and for polychaetes and
                    bivalves separately. Capitellid spp. were not identified to species and are not included in
                    the polychaete data. Data are from 6 "clarn gun" cores per station; each core had a diameter
                    of 15 cm (area 177 cm2) and was 20 cm in depth.

                                                    Station                 North                  South

                    All macroinvertebrates          1 (near mouth)          15.17 (1.1)            10.83(0.9)
                                                    3 (upstream of 1)       4.17(0.4)              3.67(0.56)
                                                    5 (upstream of 3)       10.83 (0.65)           1.67(0.5)
                                                    7 (upstream of 5)       3.00(0.37)             2.3(0.42)

                    No. of Polychaete spp.          1                       6.17(0.79)             6.17(0.47)
                                                    3                       3.00(0.26)             0.67(0.33)
                                                    5                       2.83(0.60)             0.67(0.33)
                                                    7                       1.50(0.56)             0.00

                    No. of Bivalve spp.             1                       3.67(0.61)             2.33(0.56)
                                                    3                       0.50(0.22)             1.83(0.40)
                                                    5                       3.33(2.45)             0.33(0.21)
                                                    7                       0.67(0.33)             0.17(0.17)







                    Table 6.2. Densities of macroinvertebrates in the north and south channels of Tijuana
                    Estuary in November 1988. Data are mean numbers per core sample (n = 6 cores/station)
                    and standard errors (s.e.). Stations are as in Table 6.1.

                                                    Station                   North                 South

                    Capitellid worms                1                       2.5(0.67)           114.7 (2.11)
                                                    3                       0.17(0.41)             1.5 (0.81)
                                                    5                       8.83 (2.61)            0.00
                                                    7                       0.33 (0.33)            0.00

                    Other Polychaetes               1                       19.00 (5.52)           13.17  (1.22)
                                                    3                       6.83(2.45)             1.00(0.37)
                                                    5                       5.17 (1.74)            1.33 (2.45)
                                                    7                       5.67(2.80)             0.00

                    Bivalves                        1                       10.17 (1.35)           3.67(l.05)
                                                    3                       0.67(0.33)             3.5 (0.62)
                                                    5                       8.33(0.99)             0.33(0.21)
                                                    7                       0.83(0.4)              0.17(0.17)





                                                                 71






                       Sampling methods and comparative data from natural wetlands


                     Table 6.3. Comparison of numbers of individuals of benthic invertebrates collected at
                     Tijuana Estuary (tidal conditions, but with sewage inflows) and Los Pefiasquitos Lagoon
                     (primarily nontidal). Taxa comprising less than 5% are listed as "others." Note that
                     sampling efforts differed for the two wetlands. Data are from Nordby and Zedler (in
                     press).
                                                                        Tijuana Estuary        Pefiasquitos Lagoon
                     Taxon

                     Sipunculid worms
                         Themiste sp.                                               17
                     Echinoderms
                         Dendraster excentdcus                                      6                       3
                     Nemertean worms                                                93                      3
                     Polychaete worms
                       Capitellidae                                                 814                  521
                       Spionidae
                         Boccardia spp.                                             68 (5 spp)           183 (4 spp)
                         Polydora comuta                                            267                  110
                         Polydora spp.                                              63 (2 spp)           210 (2 spp)
                         Spiophanes missionensis                                    117
                         Unidentified spionid                                                            163

                       Other taxa combined                                          437                  181

                     Total polychaetes collected                                    1698               1368
                     Total families collected                                       13                   11
                     Total polychaete species collected                             35                   20

                     Bivalve molluscs
                         Tagelus californianus                                      797                  40
                         Protothaca standnea                                        554                     4
                         Macorm nasuta .                                            -221                    6
                         Laevicardiwn subsViawn                                     30                      8
                         Spisuld sp.                                                                     17
                       Other species combined                                       221

                     Total bivalves collected                                 1799                       95
                     Total bivalve species -collected                               18                   12

                     Decapod crustaceans
                         Callianassa californiensis                                 234                     3
                     Phoronida
                         Phoronis sp.                                               1                    114
                     Brachiopoda.
                         Glouida albidia                                                                    1
                     Total sampling area (cumulative area in m2)
                         bivalves                                                   4.77 m2            3.34 m2
                         other taxa                                                 3.34 m2            3.34 m2
                     Total number of quarterly samples
                         bivalves                                                   10                      7
                         other taxa                                                 7                       7




                                                                  72





                   Sampling methods and comparative data from natural wetlands


                     Macroinvertebrates in the north and             Litterbag traps
                 south main channels of Tijuana Estuary
                 illustrate differences that relate to tidal             We have found litterbag traps to be
                 flushing (Tables 6.1-6.2). In November              very useful in collecting small
                 1988, the north channel (Oneonta                    invertebrates from marsh habitats. The
                 Slough) was fully tidal, while the south            placement of such traps in the wetland for
                 channel had very little tidal influence,            a month-long period allows a variety of
                 except at the station nearest the mouth.            small invertebrates (flies, amphipods,
                 Mouth stations of both channels were                beach hoppers, crabs, and snails) to
                 somewhat influenced by sewage inflows               colonize the litter and be collected easily
                 from the Tijuana River.                             without damage to the habitat. However,
                                                                     the animals trapped are an indicator of
                     Data from long-term sampling of the             what is available to colonize substrates,
                 northern arm of Tijuana Estuary (Table              and are not necessarily representative of
                 6.3) indicate that even though the estuary          densities of organisms living outside the
                 is stressed by wastewater inflows, the              traps. Thus, the method provides an
                 benthic community is still more diverse             index of this invertebrate community,
                 than that of Los Pefiasquitos Lagoon,               which is especially useful for
                 which is primarily nontidal.                        simultaneous comparisons of natural and
                                                                     man-made wetlands.
                     Historic data from Tijuana Estuary,
                 before major floods and sewage inflows,                 Stations in the upper and lower
                 serve to characterize a "healthy" benthic           intertidal marsh will attract different
                 community.       Peterson (1972, 1975,              species and densities of organisms. The
                 1977) sampled both Tijuana Estuary and              method was modifed from Levings'
                 Mugu Lagoon (340N, 1190W) in the                    (1976) basket traps. Litterbags are made
                 1970's. His data for live bivalves in               from 1-cm nylon mesh (black is
                 saline habitats show that Nuttallia                 preferred). Dried plant material weighing
                 (Sanguinolaria) nunaffli and Protothaca             40 g is placed inside each bag and the
                 staminea were the most abundant bivalves            ends of the bag are folded over and
                 at both study sites.            Tagelus             stapled. The resulting bag is about 15 x
                 californianus, Cryptomya californica,               25 cm. For litter as filler, Rutherford
                 Macoma nasuta, and Laevicardium                     (1989) used dried cordgrass, (Spartina
                 substriatum were also present but in                foliosa) left over from harvests of
                 lower numbers.                                      experimental material at PERL. In
                                                                     comparisons using native cordgrass and
                     Hosmer (1977) sampled bivalve                   commercial straw, it was clear that straw
                 composition and measured the sizes of               trapped fewer animals. Comparisons
                 representatives of each species. Large              between native cordgrass and a mixture
                 individuals were abundant. The mean                 of cattails and bulrushes gave similar
                 sizes for the dominant bivalves were: 71            results (Table 6.4). Because cordgrass
                 mm for Nuttallia nuttaffli ; 22 mm for              should not be taken from native stands,
                 Protothaca staminea ; and, 27 mm for                we recommend the use of cattails. and
                 Tagelus californianus. His results                  bulrushes from man-made wetlands.
                 contrast with recent data, i.e., Nuttallia
                 nuttallii no longer exists at Tijuana                   Three replicate litterbags should be
                 Estuary, and P. staminea is, on the                 placed at.each sampling station. Stations
                 average, half as large.                             of about 2 m in diameter are convenient.
                                                                     Bags are secured at the soil surface with
                                                                     wire flagging stakes. Seasonal sampling
                                                                     produces different dominants, with the
                                                                     largest numbers of individuals occurring
                                                                     in winter. Litterbags should be left in the


                                                               73






                            Sampling methods and comparative data from natural wetlands


                          marsh for one month, then collected and                 constructed wetland. Rather, simul-
                          placed in zip-lock storage bags containing              taneous sampling in natural and man-
                          a 10% buffered formalin seawater                        made marshes is recommended. At the
                          solution. Litterbags may be stored in                   Sweetwater River Wetland Complex, a
                          formalin for up to 5 days before gently                 comparison of natural and constructed
                          washing the litter over a 0.5 mm sieve to               habitats (Rutherford 1989) shows that
                          collect the organisms. The catch is                     about 3 times as many individuals and
                          preserved in 70% isopropyl alcohol, and                 consistently more species were collected
                          identification requires microscopic                     in the natural marsh than in the mitigation
                          (dissecting scope) examination.                         marsh, which was assessed 4 years after
                                                                                  construction.

                                                                                      Results from bags collected in
                              Reference data for litterbag                        January 1989, after one month in the
                          traps. Data from Tijuana Estuary,                       Tijuana Estuary, are provided to indicate
                          Sweetwater Marsh, and Paradise Creek                    the kinds of species collected in litterbag
                          all indicate that sampling time and                     traps. The data are from the lower marsh
                          location are important variables. No set                and adjacent mudflats. Only the results
                          of data can be recommended as a                         for bags made using Spartina are
                          reference point with which to compare a                 presented.





                          Table 6.4. Relative abundance (% of total) of invertebrates trapped in litter bags that
                          were filled with dried Spartina, Typha, or Scirpus. Litter bags were placed in Paradise
                          Creek Marsh for the month of March 1989. Each site had 4 replicate bags. The %
                          similarity of invertebrate composition (based on abundance) comparing Spartind and Typha
                          litter bags was 78%, comparing Typha and Scirpus was 75%, and comparing Scirpw and
                          Spartina was 86%.

                                                                              S                             Sdrj2US
                                                                                 Pa           Typ h a

                                 Pericoma spp. (fly larva)                       78.4            58.4           83.1
                                 Collembola (springtails)                         5.8            6.2             <1
                                 Tromboidea (???)                                 5.8            4.5             2.4
                                 Assiminea californica (small snail)              3.9            5.1             1.3
                                 Unknown larvae                                   1.2            8.0             4.7
                                 Capitellid worms (polychaete)                    1.6            6.6             5.1
                                 Orchestia traskiana (amphipod)                   <1             7.6             2.0
                                 Ligia occidentalis (isopod)                      <1             2.4             <1
                                 Saldidae (fly)                                   1.8            <1              <1
                                 Other                                            <1             <1              <1














                                                                           74





                      Sampling methods and comparative data from natural wetlands



                    Table 6.5. Invertebrates collected at three stations, 2 intertidal elevations per stations, in
                    the north channel (Oneonta Slough) of Tijuana Estuary. Station 1 (S 1) was near the ocean
                    inlet; station 7 was a tidal creek near the northern limit of the wetland. Spartina was used
                    as filler for all bags.. Four taxa with only 1 individual in n=18 bags were included in the
                    total but not listed.


                                                  S1      Sl       S6       S6     S7       S7
                        Oreanis                 lower upp        lower uppe       lower uppe          Mean        s. e,

                    Capitellidae                   6        0       2       0       5          9       3.7        1.5
                    Spionidae                     61        0       0       0       0          1      10.3        10.1
                    Polydora ligni                 0        0       0       0       7          0       1.2        1.2
                    Streblospio benedicti          0        0       0       0       2          0       0.3        0.3
                    Assiminea californica          0      27        0     206       2       72        51.2        33.0
                    Melampus olivaceus             0        0       0       0       0.         4       0.7        0.7
                    Hemigrapsus oregonensis 26              0       9       0      32       10        12.8        5.5
                    Pachigrapsis crassipes        23      14        19      5       3          0      10.7        3.8
                    Juvenile crab                 I 1       0       8       2       7          5       5.5        1.6
                    Orchestia traskiana            4      17        4       6      12       45        14.7        6.4
                    Other amphipods                0        0       0       0      12          0       2.0        2.0
                    Ligia occidentalis             0      18        0       0      22       76        19.3        12.1
                    Diptera.                       2      45        0       1       0          0       8.0        7.4
                    Dipteran larvae                1        2       0       5       5       35         8.0        5.5
                    Dipteran larvae B              0        0       0       0       3          0       0.5        0.5
                    Pupae                          3      25        0       3       0          2       5.5        3.9
                    Unknown larvae                 0        1       0       1       0          0       0.3        0.2
                    Unknown insect                 0        0       0       3       0          3       1.0        0.6

                    Totals                       137     149       42    235      112      263      156.3       33.2





























                                                                   75





                         Sampling methods and comparative data from natural wetlands


                                                                              released outside the blocking nets.
                       7. Fishes:               Community                     Repeated tows must be made and
                                                                              continued until the total number of fishes
                        dynamics, controlling                                 collected declines' in two successive
                                       factors                                seifiings. The first and second seinings
                                                                              capture the water-column species, while
                                                                              later seinings collect bottom-dwelling
                           Objectives. Fishes         are valuable            species. Stomping on the bottom scares
                       indicators of ecosystem health.                        up benthic species (e.g., burrowing
                       Generally, the presence of few species                 gobies) that would otherwise allow the
                       (low species richness) indicates stressful             net to drag over them. The blocking nets
                       environmental conditions. Gobies and                   are then closed by drawing the two
                       mullet are relatively tolerant of                      together in a serni-circle and then pulling
                       environmental extremes and are among                   them to shore, thereby capturing those
                       the last species to disappear., Fishes are             fishes that managed to escape the bag
                       valued as foods for birds that use the                 seine. The successive seining results can
                       estuary. A few species are of recreational             be used to estimate total population size,
                       or commercial interest, e.g., California               using the standard catch-per-unit-effort
                       halibut and longjaw mudsuckers (as                     technique, plotting number per catch
                       baitfish).                                             against cumulative catch and extrapolating
                                                                              the line to obtain the cumulative catch
                           Methods.         Fishes are sampled                when catch is zero. The area seined
                       quarterly (March, June, September, and                 (length of segment and channel width)
                       December) at replicate stations. The                   should be measured so that densities can
                       habitat types to be sampled for fishes                 be calculated on a per-surface-area basis.
                       include deep channels, tidal creeks, deep              Maximum depths are recorded.
                       saline ponds, brackish creeks, and
                       freshwater ponds. Fish sampling is                         Reference data comparing. two
                       carried out at moderate tide levels, when              fish sampling techniques.                  To
                       stations are accessible by fb9t. Sampling              demonstrate the need for repeated seining
                       at times of moderate tidal amplitude also              to obtain representative data for fish
                       avoids tidal transport of transient species.           densities and species composition, a fish
                                                                              sampling exercise was carried out by
                           Blocking nets prevent fish from                    Chris Nordby At the "east-west channel"
                       escaping the sampling area. Standard                   at Tijuana Estuary on March 11, 1987. A
                       mesh size allows comparisons among                     10-m segment of the channel was blocked
                       seining efforts. Adult and juvenile fishes             at each end with seines of 3-mm, mesh,
                       should be collected using 3-mm mesh                    and the blocked area was sampled with a
                       blocking nets and bag seine. The 3-mm                  third 3-mm. seine in four repeated efforts.
                       size mesh ensure the capture of small yet              Each of the four seining efforts was equal
                       ecologically important.goby species. A                 in area and seine length. Then, the two
                       linear distance (e.g., 10-15 m) parallel to            blocking nets were "closed" by pulling
                       the creek or channel sampled should be                 each toward the center. The combined
                       measured and the channel nets deployed                 fish catch in this fifth seining effort was a
                       to confine all fishes within the two nets.             double effort, so the numbers of fish
                       The bag seine is then drawn in a circle                caught were halved to compare with the
                       within the blocking nets and pulled to                 first 4 seining efforts. Water depth was
                       shore. For pond habitats, a semicircular               approximately 1 ni on the outgoing tide.
                       area should be enclosed with a net seine,
                       and the seine drawn toward the shore.                     Using the catch-per unit effort method
                       The species composition and numbers                    (Figure 7.1), it was determined that the
                       collected per tow are recorded, a                      total fish population within the blocked
                       subsample measured (for length-                        portion of the channel was 1470 fish
                       frequency distributions), and fishes                   (Y=159 -0.108X; for Y=O, X=1470; i.e.,


                                                                       76





                   Sampling methods and comparative data from natural wetlands


                 when no more fish would have been                          Additional sampling showed that
                 present, 1470 would have been caught).                 gobies were the dominant members of the
                 This catch-per-unit-effort calculation                 fish community. Gobies are bottom-
                 provides a good estimate of total                      dwelling species that respond to the
                 population when sequential catches                     repeated disturbances of seining; their
                 decline smoothly, as in this examnple.                 numbers increased progressively in the
                 However, in many cases, a catch with                   first three seinings (Figure 7.2), and
                 few fish can be followed by one with                   declined slightly in the last two efforts.
                 many fish, as gobies move into the water               Two mullet were caught in the later
                 column.       We recommend seining                     seinings, but were not included in these
                 sequentially until the catch is clearly                data summaries; it is well known that
                 diminished, then summing the numbers                   seines undersample mullet because they
                 caught to estimate the number of fish per              swim or jump out of the seines.
                 area.
                                                                            We conclude from this comparison
                     In the test case (Table 7.1), the first            of seining methods that: A single seining
                 seining yielded 157 fish; which was only               can underestimate fish density by as
                 about 10% of the estimated fish that could             much as an order of magnitude. A single
                 have been caught there. For the 5 com-                 seining can misrepresent the fish
                 parable seining efforts, a total of 643 fish           community; the most catchable species
                 were recorded. Of these, 395 were                      will appear to be the most abundant ones,
                 gobies, 160 topsmelt, 64 sculpin, 11                   while the least catchable species will be
                 killifish, and 13 flatfish.                            absent or undersampled. In this data set,
                                                                        repeated sampling produced only one
                                                                        additional species (mullet), one that is
                                                                        generally undersampled due to its net
                 Table 7.1. Comparison of single and                    avoidance behavior.
                 repeated seining efforts at Tijuana
                 Estuary. Data are relative abundances,
                 obtained by C. Nordby, SDSU, on
                 March 11, 1987. Species that appeared
                 to be dominant are shown in bold type.

                                    lst seining      Total in 5
                                        effort

                   Topsmelt          70.1%               24.9%
                   Gobies                 6.4             61.4
                   Sculpin               17.8             .10.0
                   Killifish              4.5                1.7
                   Flatfish               1.3               2.0





                     The first seining suggested that
                 topsmelt were dominant; however, as
                 repeated seinings show, they are merely
                 the most catchable species. In fact, 69%
                                                                           4091- P__

                 of the topsmelt found were caught on the                           Staghorn sculpin
                 first seining. Topsmelt are water-column                           (Leptocottus armatus)
                 species that do not readily avoid seines.



                                                                 77





                    -Sampling methods and comparative data from natural wetlands

                    Figure 7.1. Repeated seining of a blocked channel plotted against the prior cumulative
                    catch. Data of C. Nordby, PERL.


                                 160-                                A
                                               y   158.66 - 0.10657x R 2  0.862



                                 140-
                            .C




                                 120-


                            Cn


                                 100-





                                  80-
                                     0     100     200      300     400     500      600
                                              Prior Cumulative Catch






                    Figure 7.2. Species composition of repeated seinings. Data of C. Nordby, PERL.


                            175-


                            150-


                            125-
                      0                                                                       Total fish
                            100-                                                              Goby
                                                                                              Topsmelt
                      ILL                                                                     Flatfish
                              75-                                                             Killifish
                                                                                       a      Sculpin
                              so-


                             25


                              0
                                 0       1       2        3        4        5        6

                                                   Seine Number






                                                         78





                  Sampling methods and comparative data from natural wetlands


                    Reference data for fishes of                wetland.    However, the differences
                wetland channels. Nordby has used               between the two systems have helped to
                the same sampling methods to assess             show patterns of decline that follow
                populations of fishes at Tijuana Estuary        hydrologic disturbances. Low numbers
                and Los Pefiasquitos Lagoon for several         of species and single-species dominance
                years (Table 7.2, Nordby and Zedler in          indicate low-quality habitat; absence of
                press). The sampling program indicates          longjaw mudsuckers may indicate a
                large differences in species composition        recent period of hypersalinity; the
                and density for the two wetlands and for        presence of mosquitofish indicates high
                stations within Tijuana Estuary.                or persistent fi-eshwater inflows.
                Differences are related to the history of
                hydrologic disturbances at the two                  The total species lists (Table 7.3) for
                wetlands, with Tijuana Estuary being            Tijuana Estuary and Los Peffasquitos
                open to tidal flushing at all times during      Lagoon indicates fewer species in the
                the sampling and Los Pehasquitos                latter wetland, but note that the sampling
                Lagoon closing annually for much of the         effort was also less.
                warm season. During the closures, there
                were floods in both October 1987 and                Ichthyoplankton sampling. If
                December 1988, the fresh water was              juvenile or adult fishes are not found
                impounded, and large numbers of fish            using seines, the habitat might still be
                were killed after salinity and oxygen           suitable but larvae may not be available
                levels dropped. At Tijuana Estuary, raw         for settling. In this case, ichthyoplankton
                sewage inflows were persistent each             sampling should be considered to
                year, and the sampling station closest to       determine if young are available for
                the Tijuana River was most depleted of its      colonization. The lack of ichthyo-
                fish community.                                 plankton would indicate that a basic
                                                                ecosystem function is missing. Two
                    Both types    of hydrologic modifi-         periods are recommended for sampling
                cations are human impacts--the sewage           ichthyoplankton--sampling in March will
                flows from Mexico have changed the              capture nearshore species that move into
                river from an intermittent stream to a          the estuary with tidal waters, and,
                year-round, nutrient-rich river that is         sampling in April will assess availability
                laden with toxic materials. The pro-            of larvae of resident species such as
                longed closure to tidal flushing has            topsmelt and gobies. Nordby (1982)
                resulted from the construction of roads         gives detailed information on the year-
                and a railroad (and associated filling and      round distribution of ichthyoplankton at
                reduced tidal prism). Thus, none of the         Tijuana Estuary.
                fish communities we describe serves as a
                reference datum for a "healthy" tidal


                Table 7.2. Fishes in two southern California coastal wetlands (from Nordby and Zedler
                in press). Data are relative abundances (% of total caught in multiple censuses each year).

                                                          Tijuana Estuary                 Peffasquitos Lagoon
                Species                             1986-87     1987-88    1988-89         1987-88    1988-89

                Atherinops affinis                     52          14           7            38          36
                Clevelandid ios                        41          58         90             22          14
                Fundulus parvipinnis                    4         .19           1              4           2
                Giffichthys mirabilis                             <1          <1             28          14
                Gambusia affinis                                                             <1          24
                Others                                  3         -8          -1             -7          10



                                                              79





                        Sampling methods and comearative data from natural wetlands



                        Table 7.3. Fish species collected at Tijuana Estuary and Los Peiiasquitos Lagoon (modified
                        from Nordby and Zedler in press). X = less than 1% of annual catch.

                                                                                                         Tijuana    Peilasquitos
                                                                                                         Estuary       Lagoon
                             Taxon                                             Common name               1986-88      1987-88

                        Atherinidae           Atherinops affinis             topsmelt                     15,437        1,875

                        Blennidae             Hypsoblennius gentilis         bay blenny                       x
                                              Hypsoblennius gilberd          rockpool blenny                  x
                                              Hypsoblenniusjenkinsi          mussel blenny                    x
                        Bothidae              Paralichthys califomicus       California halibut               x            x

                        Cottidae              Leptocottus arniaw             staghom sculpin               1,431         346
                                              ArteWus sp.                    sculpin                          x

                        Cyprinodontidae       Fundulus paryipinnis           California killifish          2,367         107

                        Engraulidae           Anchoa contpressa              deepbody anchovy                 x            67

                        Girellidae            Girella nigricans              opaleye                          x            x

                        Gobiidae              Clevelandia ios                arrow goby                  60,097          816
                                              Giffichthys mirabi&            longjaw mudsucker               275         877
                                              Ilypnus gilberd                cheekspot goby                   x            x
                                              Lepidogobius lepidw            bay goby                                      x
                                              Quietuld y-cauda               shadow goby                      x
                        Mugilidae             Mugil cephalus                 striped mullet                   x            x

                        Plueronectidae        Hypsopsew gumlata              diamond turbot                   x            x
                                              Plueronichthys ritwi           spotted turbot                   x

                        Poecilfidae           Garnbusid affinis              mosquitofish                                937

                        Rhinobatidae          Rhinobatus productus           shovelnose guitarfish            x

                        Serranidae            Paralabrax clathraw            kelp bass                        x

                        Sciaenidae            Seriphus politus               queenfish                        x

                        Syngnathidae          Syngnathus leptorynchus        bay pipefish                     x            x


                        Total fishes    collected                                                      80,165        5,087
                        Total species encountered                                                             21           13
                        Total sampling effort (cumulative area in M2)                                     4,795       1,985
                        Number of quarterly samples                                                           12           8





                                                                        80





                    Sampling methods and comparative data from natural wetlands


                                                                         Aerial photos should be used to select
                                 8. Birds                                areas of relatively homogeneous
                                                                         vegetation and topography. Several short
                      Objectives. The most obvious and                   transects should prove more useful than a
                                                                         few long transects in comparing mean
                  widely appreciated animals of the coastal              densities among habitat types, as the
                  wetlands are the birds. In recent years,               standard errors are likely to be lower
                  several studies have quantified coastal                (Hanowski et al. 1990). Census dates
                  wetland birds (Boland 1981, 1988) and                  and times are then selected, keeping in.
                  identified their functional roles (Boland              mind that coastal bird communities
                  1988, Quarnmen 1984). Additional work                  change with season, with inclement
                  on endangered species has been done,                   weather, and with tidal condition. Patrice
                  and some sites are monitored yearly for                Ashfield and Barbara Kus (see below)
                  target species (US FWS). However,                      sample weekly during most of the year
                  long-term monitoring programs of the                   (biweekly in summer) in order to
                  total bird community are still needed.                 compare bird communities at high tide
                  Because birds are a major linkage                      and low tide, and in order to follow
                  between wetlands, coordinated monitor-                 changes with migration.
                  ing programs of all water-associated birds
                  throughout the Pacific flyway are needed.                  Reference data. A detailed, year-
                  In addition, we need to determine how                  long sampling program was initiated at
                  different habitats attract birds and the               Tijuana Estuary during 1988-89 (B. Kus
                  length of time it takes target species to              and P. Ashfield, SDSU, pers. comm.).
                  find and use constructed wetlands.                     The program had weekly censusing of
                      Bird community sampling.                           shorebirds and waterfowl (density by
                  Several methods have been developed for                species) during months of high activity
                  sampling terrestrial birds (Ralph and                  (Oct.-Dec.) to include weeks with both
                  Scott 1981), which pose special problems               spring and neap tides. Thereafter (Jan.-
                  because of their high mobility and low                 June), censuses were biweekly, and only
                  visibility in areas of dense vegetation. In            at low tide. In this sampling program,
                  coastal wetlands, many of the species of               counts were recorded by habitat type
                  interest are fairly large, occur in groups,            within three main transects. The two
                  and feed in the open.             Flocks of            transects with greatest bird activity were
                  shorebirds are highly visible. Still, there            censused simultaneously by qualified
                  are difficulties in selecting consistent               observers, to allow comparison under the
                  habitat areas, since tides expose different            same tidal conditions.         The weekly
                  widths of shoreline each day. Observers                surveys alternately characterized bird use
                  need to be skilled in estimating distances,            under low and high tides. Censuses
                  since counts of birds per area could easily            began one hour before the tide condition
                  be biased when transects; of unmeasured                that was being characterized. Observers
                  width are censused. Walking transects                  carried binoculars, a spotting scope, and
                  along shorelines allows counts to be                   a two-way, radio to maintain contact with
                  expressed as number per length of                      one another and reduce duplicate counting
                  transect, even if transect width varies.               of individuals flying between transects.
                  However, data from transects of fixed                  Counts were made by species, noting the
                                                                         specific habitat type (Table 8. 1),
                  width and length are easiest to analyze.
                                                                         inundation level (with or without standing
                  Boland (1988) used multiple transects of               water) and noting behavior within three
                  fixed length (50 m) to obtain densities                classes: foraging, roosting, or flying.
                  (means and standard errors) for each                   During each visit, additional notes were
                  habitat.                                               made on selected species (raptors,
                      Habitat types are first delineated, and            Belding's Savannah sparrows, and light-
                  transects chosen to represent each area.               footed clapper rails) that were seen
                                                                         outside the regular transect.


                                                                  81





                        -Sampling methods and comparative data from natural wetlands


                        Table 8.1. Habitat types used in censusing birds at Tijuana Estuary (B. Kus, SDSU,
                        pers. comm.) .

                                                Habitat                                     Subhabitats

                                Beach                                   Lower (surf line) and Kelp (wrack)
                                Dune (sandy beach in estuary)           Distance from channel: within 3 m and >3 m
                                Unvegetated intertidal                  Inlet, Cobbles, Channel
                                Vegetated intertidal                    Distance from channel: 0-5 m, >5 m
                                Salt panne (bare flats, often dry)




                        Table 8.2. Summary data for birds censused along dime transects within Tijuana Estuary
                        in 1988-89. Data from Kus and Ashfield (SDSU, unpub. data). Data for biweekly low-
                        tide censuses are for the period of October 7, 1988, through April 8, 1989.


                                Group                                    No. of                   % of individuals*

                                Small waders                                     14                    37.31
                                Gulls and terns,                                 13                    27.84
                                Large waders                                       8                   18.24
                                Waterfowl                                        16                    14.45
                                Herons and egrets                                  7                     0.47
                                Raptors                                            9                     0.39
                                Grebes and pelicans                              -5                      0.14
                                Land birds                                       18                  not included

                                Total number of species                          90

                                Total, sightings in low tide censuses on 14 dates                    25@572




                        Table 8.3. Percent of total observations in each of 5 habitats during low tide surveys on
                        14 dates of the northern half (the most well-flushed portion) of Tijuana Estuary. There
                        were 23,298 bird sightings within these groups in the two northern transects.

                                                     Small      Gulls,     Large      Water-      Herons      Grebes,
                                 Habitat             waders     tems       waders     fowl        egmts;      pelicans

                        Unvegetated intertidal       77.2       22.3       72.7       98.7        92.9        89.5
                        Vegetated intertidal         0.5        0.0        2.1        0.7         6.1         0.0
                        Beach (open coast)           1.3        5.4        2.6        0.0         .0.0        0.0
                        Dune (beach in estuary       14.8       6.0        17.9       0.6         1.0         0.0
                        Island                       6.2        66.3       4.8        0.1         0.0         10.5

                        Total sightings              8,221      7,159      4,458      3,343       98          19



                                                                      8 2





                       Sampling methods and comparative data from natural wetlands


                     Table 8.4. Species list for 7 groups of birds at Tijuana Estuary (Kus and Ashfield, unpub. data).
                     The list of land birds includes only species seen at the three census locations.

                     Small waders                                                     Gulls and terns
                     Actitis macularia                 Spotted sandpiper              Larus phdadelphia                 Bonaparte's gull
                     Pluvialis squatarola              Black-bellied plover           L. heermanni                      Heermann's gull
                     Chara&ius vociferus               KiUdeer                        L. delawarensis                   Ring-billed gull
                     C. sendpalmatus                   Semipalmated plover            L. canus                          Mew gull
                     C. alexamWnus                     Snowy plover                   L. californicus                   California gull
                     Arenaria interpres                Ruddy turnstone                L. argentatus                     Herring gull
                     A. melanocephala                  Black turnstone                L. occidentalis                   Western gull
                     Calidris canutus                  Red knot                       Sterna caspia                     Caspian tern
                     C. mauri                          Western sandpiper              S. maxima                         Royal tern
                     C. minutilla                      Least sandpiper                S. elegans                        Elegant tern
                     C. alpina                         Dunlin                         S. hirundo                        Common tern
                     C. alba                           Sanderling                     S. forsteri                       Forster's tern
                     Gallinago gallinago               Common snipe                   Rynchops niger                    Black skimmer
                     Rallus longirostris levipes       Light-footed clapper rail
                                                                                      Pelicans, grebes, and cormorants
                     Large waders                                                     PoXlymbuspoeiiceps                Pied-billed grebe
                     Himantopus mexicanus              Black-necked stilt             PoiUceps nigricollis              Eared grebe
                     RecurWrostra americana            American avocet                Aechmophorus occidentalis         Western grebe
                     Catoptrophorus semipalmatus       Willet                         Phalacrocorax auritus             Double-crested
                     Tringa sp.                        Yellowlegs                                                         cormorant
                     Numenius phaeopus                 Whimbrel                       Pelecanus occidentalis            Brown pelican
                     N. americanus                     Long-billed curlew
                     Limosafedoa                       Marbled godwit                 Herons and egrets
                     Limnodromus sp.                   Dowitchers                     Ardea herodias                    Great blue heron
                                                                                      Casmerodius albus                 Great egret
                     Waterfowl                                                        Egretta caendea                   Little blue heron
                     Branta canadensis                 Canada goose                   E. rufescens                      Reddish egret
                     Anas amencana                     American wigeon                E. thula                          Snowy egret
                     A. strepera                       Gadwall                        Nycticorar nyclicorax             Black-crowned
                     A. crecca                         Green-winged teal                                                  night heron
                     A. platyrhynchos                  Mallard                        Phoenicopterus sp.                Flamingo
                     A. acuta                          Northern pintail
                     A. discors                        Blue-winged teal               "Land birds"
                     A. cyanoptera                     Cinnamon teal                  Ceryle alcyon                     Belted kingfisher
                     A. clypeata                       Northern shoveler              Sayorms nigricans                 Black phoebe
                     Aythya affinis                    Lesser scaup                   Sayornis saya                     Say's phoebe
                     Melanittaperspicillata            Surf scoter                    Eremophila alpestris              Horned lark
                     Bucephala clangula                Common goldeneye               Hirundo rustica                   Barn swallow
                     B. albeola                        Bufflehead                     Corvus corax                      Common raven
                     Mergus serrator                   Red-breasted merganser         Lanius ludovicianus               Loggerhead shrike
                     Oxyurajamaicensis                 Ruddy duck                     Cistothoruspalustris              Marsh wren
                     Fulica americana                  American coot                  Thyromanes bewickii               Bewick's wren
                                                                                      Chamaeafasciata                   Wrentit
                     Raptors                                                          Anthus spinoletta                 Water pipit
                     Asio flammeus                     Short-eared owl                Carpodacus me.)dcanus             House finch
                     Pandion haliaetus                 Osprey                         Geothlypis trichas                Common yellow-
                     Elanus caeruleus                  Black-shouldered late                                              throat
                     Circus cyaneus                    Northern harrier               Passerculus sandiiich-            Belding's Savannah
                     Accipiter cooperii                Cooper's hawk                    ensis beldingi                    sparrow
                     Buteojamaicensis                  Red tailed hawk                Melospiza melodiaa                Song sparrow
                     Falco sparverius                  American kestrel               Sturnella neglecta                Western meadowlark
                     F. columbarius                    Merlin                         Columba livia                     Rock dove
                     F. peregrinus                     Peregrine falcon               Mimus polyglottos                 Northern mockingbird



                                                                          83






                        Sampling methods and comparative data from natural wetlands



                      Figure U. Temporal variability in numbers of sight    ings for the most common groups
                      of birds using Tijuana Estuary (Kus and Ashfield, unpub. data).



                              IM
                              C
                                 150O.J
                              CM                                                              Gulls and tems


                                 1000-                                                 0
                                                                                              Small waders
                              P

                              0
                              -J  500-
                              0                                                        -      Large waders
                                                                                       0      Waterfowl
                                                          W
                                    04t 7                Jan I"        Mar 10
                              E                                                     200
                                                     1988-1989
                              Z







                         Sweetwater River Wetland                      Santa Margarita Estuary. Birds
                      Complex (SRWC). For her M.S.                 were censused biweekly at SME for one
                      thesis, Ashfield (in prep.) censused birds   year, beginning April 1986 (Hollis et al.
                      along several permanent transects along      1988). During late winter/early spring of
                      San Diego Bay. Weekly sampling for           1987, the ocean inlet closed, and the
                      most of the year (biweekly in summer)        reduced abundance and diversity of birds
                      provided sufficient data to compare bird     was attributed to reduced tidal flushing.
                      use. during both high and low tides.         Coots increased and ruddy ducks were
                      Some of her results have been                higher than the previous year, while other
                      summarized and used in evaluating the        water birds had reduced numbers.
                      bird community of the constructed marsh      Shorebird use was characterized as
                      (Section IH); the relative abundances for    especially low in recent years. Habitats
                      the two natural wedand sites are repeated    sampled included willow woodland, river
                      here (Table 8.5), with rare species          channel, marsh, ponds, salt flat, and
                      included. When completed, Ashfield's         sewer ponds. Densities were lowest
                      thesis should be consulted for details of    from May-July and highest from late fall
                      other sampling locations and seasonal        to early spring.
                      patterns of abunda nce.





                                                                 84





                        Sampling methods and comparative data from natural wetlands


                     Table 8.5. Water- as soci ated birds at               Other bird counts. Local sources
                     SRWC. Data of Ashfield (in prep.) are             of information on bird use may provide
                     for 13 months in 1989-90, for low-tide            important historical records.             The
                     censuses, for all species (excepting gulls)       Audubon Christmas Bird Count data
                     that made up >0. 1 % of the sightings. PC         from wetland sites should be obtained on
                     = Paradise Creek and BS = Bay                     an annual basis (published in special
                     Shoreline off Gunpowder Pt.                       editions of American Birds). In addition,
                                                                       the Pt. Reyes Bird Observatory (4990
                     % of total sighting-S            PC     BS        Shoreline Highway, Stinson Beach, CA
                                                                       94970) has information on shorebirds for
                     Western sandpiper                15.5   40.6      selected coastal water bodies. A recent
                     Dowitcher spp.                   25.0   11.7      effort of the Observatory was to count
                     Willet                           20.0   7.2       shorebirds in all wetlands between Baja
                     Marbled godwit                   4.9    8.5       California and British Columbia on a
                     Red knot                           0    8.7       single date, April 22, 1989. This is a
                     Dunlin                           5.7    1.7       very useful comparative data base. For
                     Bufflehead                       6.6       0      San Diego County, the census resulted in
                     Killdeer                         4.3    0.1       over 12,000 shorebird sightings, of
                     Great blue heron                 4.0    0.1       which approximately 75% were small
                     Surf scoter                        0    3.8       waders (over 50% were western
                     Lesser scaup                     0.3    3.3       sandpipers). The largest concentration of
                     Western grebe                      0    3.1       shorebirds was in south San Diego Bay,
                     Least sandpiper                  2.1    0.7       with the next largest group in the Flood
                     Pied-billed grebe                2.3    <. 1      Control Channel of the San Diego River.
                     Snowy egret                      1.2    1.0
                     Long-billed curlew               1.6    0.5           Endangered bird populations.
                     Brant                              0    1.9       Clapper rails are censused during the
                     Great egret                      1.7    0.1       breeding and nesting season by listening
                     Black-bellied plover             0.2    1.6       to their calls. Observers stand quietly at a
                     Black-necked stilt               1.4       0      vantage point. Calls are most frequent at
                     Spotted sandpiper                1.2       0      dusk, and surveys begin 0.5 hr before
                     Greater yellowlegs               0.5    0.6       dusk and last 0.5-1.0 hr after dark,
                     Forster's tern                   0.7    0.3       depending on calling activity. Less
                     Northern pintail                   0    0.9       calling leads to longer census periods.
                     Sernipalmated plover               0    0.8       Experts can often distinguish paired and
                     Ruddy turnstone                    0    0.5       unpaired birds by their call: a "clatter"
                     Sanderling                         0    0.4       call usually indicates a pair especially if
                     Mallard                          0.3       0      the male and female call in a duet; a "kek"
                     American widgeon                   0    0.3       call is made by a searching male or
                     Northern shoveler                  0    0.3       female. Unpaired females searching for a
                     Black-crowned night-heron        0.2       0      mate is a third type of call.
                     Red-breasted merganser           0.2       0
                     American avocet                  0.2       0          In addition, the presence of rails can
                     Least tern                         0    0.2       be identified using recorded calls (during
                     Black skimmer                      0    0.2       the territorial season), following the
                     Homed grebe                        0    0.2       techniques developed by Barbara Massey
                     Brown pelican                      0    0.1       (Endangered species consultant, Long
                     Green-winged teal                  0    0.1       Beach), Dick Zembal (US FWS, Laguna
                     Snowy plover                       0    0.1       Niguel), and Paul Jorgensen (Calif. Dept.
                     Whimbrel                           0    0.1       of Parks and Recreation).

                     Total number of species 23              39




                                                                     85





                         Sampling methods and comparative data from natural wetlands


                           The recovery plan for the light-footed       Table 8.6. Historical data for light-
                      clapper rail (LFCR Recovery Team 1977,            footed clapper rails in southern California
                      p. 15) states the objective of increasing         (R. Zembal and B. Massey, US FWS,
                      the breeding population to "at least 400          unpub. report). Not all 35 wetlands were
                      pairs by preserving and restoring                 censused every year.
                      approximately 4,000 acres of wetland
                      habitat in at least 15 marshes..." Data for                                   No. of marshes
                      several years (Table 8.6) show high               Year        No. of pairs       with LFCR
                      variation in the rail population, with all
                      values well below the target of 400 pairs.        1980             203              11
                                                                        1981             173              15
                                                                        1982             221              18
                                                                        1983             249              18
                                                                        1984             277              19
                                                                        1985             142              14
                                                                        1987             178              ---









                      Figure 8.2. Importance of selected southern California wetlands to the region's
                      population of light-footed clapper rails. Data are percent of total birds censused, by year.



                         C       100%_
                         0

                         cis
                         :3      so%-
                         CL                                                                             Carpinteria Marsh
                         0
                                 6001.-                                                            0    Anaheim Bay
                                                                                                   E3   Mission Bay (K-F Res.)
                         0                                                                              Upper Newport Bay
                                 40%-
                                                                                                        Sweetwater R. Wetlands
                         0       20%-                                                                   Tijuana Estuary

                         4)
                         0
                                  0%_
                                                          04       CV)                    WIWI
                         CL               OD      CO      CO       CO     CO      CD      CD
                                                                   0)     0)      0)      0)












                                                                      86





                        Sampling methods and comparative data from natural wetlands


                     Figure 8.3. Dynamics of the light-footed clapper rail populations at three wetlands in
                     southern California. The population at Tijuana Estuary crashed while the ocean inlet was
                     closed to tidal flow (April to December 1984).



                                 50-

                                                                                    -       Tijuana Estuary
                                 40-                                                -       Sweetwater R. Wetlands

                                                                                            Mission Bay
                        LL       30-


                        0
                                 2o-
                        W



                                 10-




                                  0
                                   1978      1980     '1982        1984     1986        1988






                         California       least    terns are       Table 8.7. Historical data for California
                     monitored for type and extent of habitat      least tern breeding population (for state of
                     use (when present, April-Nov.) in both        California), as summarized in the US
                     constructed and reference channel             FWS Biological Opinion (Steucke 1988).
                     habitats. Feeding rates are recorded, and
                     type and quantity of food use are                 Census
                     estimated. The California Dept. of Fish
                     and Game should be consulted to advise            Early 1970's            623-763
                     on censuses and to exchange information           1982                    1015-1245
                     on the abundance of these birds                   1983                    1196-1321
                     elsewhere.                                        1984                    887-997
                                                                       1985                    954-1084
                         The recovery plan for this endangered         1986                    936-1016
                     species (CLT Recovery Team 1980, p.
                     13) states that   it at least 1,200 pairs
                     distributed among colonies in at least 20
                     coastal wetland ecosystems throughout          California least tern
                     their 1977 breeding range" would be            (Sterna albifrons browni)
                     required to restore and maintain the
                     breeding population. Historical data
                     (Table 8.7) show that the state-wide
                     population fluctuates, with no clear trend
                     for an increasing density.





                                                                 87





                      Sampling methods and comparative data from natural wetlands



                    Figure 8.4. ffistorical data for California least terns at selected sites in San Diego County
                    (E. Copper, ornithologist and least tern authority, unpub. data).



                                                                             0 -     Tijuana Estuary
                                                                                     Saltworks, San Diego Bay
                                     120.                                    111-    Sweetwater River
                              U)                                                     Chula Vista Wildlife Reserve
                              L.
                              rd     100-

                                     80
                              0
                              d      60-
                              Z
                              E
                              3      40-
                              E
                              E      20


                                      0
                                      1960            1970            1980             1990
                                                             Year



                       Belding's Savannah sparrows                 to Santa Barbara County, sununarizing
                    are censused during their spring territorial   censuses from 1973, 1977, and 1986.
                    nesting period. Territories are defended       White (1986) gives additional data for
                    by singing males, which are best               Los Pefiasquitos Lagoon and Tijuana
                    censused between 0600 and 0900 h               Estuary.
                    (White 1986). Observers carry binocu-
                    lars, walk transects through the entire
                    marsh, and count singing males separ-
                    ately from non-singing birds (which            Table 8.8. Comparative data for the
                    could be either males or females). The         Belding's Savannah sparrow in southern
                    counts of singing males estimate the           California (A. White, PERL, unpub.
                    number of breeding pairs. To carry out         data). All censuses were in March 1989
                    detailed studies of habitat use, territory     and used the same sampling methods.
                    sizes should be estimated and mapped           Numbers are for singing males, which
                    according to the method of White (1986).       indicate breeding pairs.
                                                                                               Estimated pairs
                       There are several sources of data
                    comparing populations of Belding's             Tijuana Estuary                     299-320
                    Savannah sparrow. A recent survey              Sweetwater River Marsh
                    (Table 8.8) included 4 wetlands. Zembal            Complex                          160-183
                    et al. (in press) provided data for 31         Los Pefiasquitos Lagoon                    56
                    coastal wetlands from San Diego County         Ballona. Wetland                           31



                                                                 88





                     Sampling methods and comparative data from natural wetlands

                           9. Reptiles and                                 sand or shredded newspaper to provide
                                                                           cover for trapped animals and to reduce
                               amphibians                                  fighting and predation among captives.
                                                                           Each bucket had an oversized masonite
                       Objectives. Censuses are         made to            lid, which was propped open during
                   determine the species present in various                times when traps could be checked. The
                   habitats. The functions performed by the                pitfall traps were placed 14.4 rn apart,
                   herpetofauna are not well studied.                      with 15 buckets for each sampling site.
                   Species distributions and abundances are                Drift fences were used in conjunction
                   also poorly known.                                      with the pitfall traps, to help direct ani-
                                                                           mals into the traps. Espinoza used alu-
                       Methods. Pitfall traps were used                    minum flashing, supported with wooden
                   by Hollis et al. (1988) to characterize                 stakes, and added sand at the base to act
                   reptiles and amphibians at Santa                        as a horizontal barrier. These "fences"
                   Margarita Estuary. These traps were "5-                 were 36 cm high and constructed in a
                   gallon buckets sunk in the ground with an               widened "H" shape, with parallel legs of
                   elevated wood cover. Natural debris was                 21 m and a 30.5-m cross link. Five traps
                   used to construct drift fences to direct the            were buried along each 21 -m leg (the
                   animals toward the traps." (ibid., p. 45).              middle trap also encountered the cross
                   No indication of the numbers of traps or                link), and 5 along the cross-linking fence.
                   amount of searching was provided. Only                  Fencing passed over the middle of each
                   a few species were were found (Table                    bucket, so that animals moving along
                   9.1).                                                   either side of the fence would encounter
                                                                           the trap. Espinoza also searched sites,
                       Similar methods were employed by                    looking under vegetation, debris, rocks
                   R. Espinoza (SDSU, unpub. data) in                      and other litter. Animals found were
                   1989, with sampling in ten sites ranging                measured   'from snout to vent, and the
                   from wet to upland areas (Table 9.1).                   condition of their tails noted. Direct
                   His traps were 5-gal. plastic buckets with              observations provide underestimates of
                   holes drilled in the bottom to insure                   nocturnal fauna, so are best used- in
                   drainage in case of rain. Buckets held                  conjunction with pitfall traps.


                   Table 9.1. Reference data for herpetofauna at Tijuana Estuary (1) and Santa Margarita
                   Estuary (SM), including willow woodland, coastal strand, maritime scrub and grassy habitats.

                   Order          Farnily      Common narn                        SW&ies                             SM   i

                   Anura -        Hylidae      Pacific Uwfrog                     Hyla regilla                        x   X
                       Toads,     Ranidae      Bullfrog                           Rana catesbiana                     X   X
                       frogs      Pipidae      African clawed frog (exotic)       Xenopus laevis                          X
                                  ]3ufonidae   California toad                    Bufo boreas halopidlus                  X

                   Squarnata -    Iguanidae    Great Basin fence lizard           S. occidentalis biseriatus          X   X
                       Lizards,                Side-blotched lizard               Uta stansburiana                    X   X
                       snakes                  San Diego coast lizard             Phrynosorna coronatum blainvillei       X
                                  Scincidae    Coronado (Island) skink            Eunwces skiltonianus interparietalis    x
                                  Anguidae     San Diego alligator lizard         Gerrhonotus multicarinatus webbi    x   x
                                               Silvery legless lizard             Anniella pulchra pulchra                X
                                  Colubridae   San Diego gopher snake             Pitouphis melanoleucus annectens    x   x
                                               California king snake              Lampropellis getulus californiae    X   X
                                               Harnmond two-striped garter snake  Thamnophis hammondi hamnwndi            X
                                  Viperidae    Southern Pacific rattlesnake       Crotalus viridus helleri            X
                   Testudenes     Emydidae     Southwestern pond turde            Clemmys rwrmorata palfida           X
                       Turtles



                                                                    89





                        Sampling methods and comparative data from natural wetlands


                                10. Mammals                                  At Santa Margarita River Estuary
                                                                         (Hollis et al. 1988), 30 trap lines were
                          Objective. Our knowledge of the                used in eight habitat types (dense
                      role of mammals in coastal wetlands is             Salicornia, Salicornia / Distichlis, Sali-
                      rudimentary. Part of their role in the food        cornia / salt panne, UplandlSalicornia,
                      chain is feeding on plants and being               coastal strand, maritime scrub, cattails,
                      preyed upon by raptors. Some seed                  and willow woodland. Each of the lines
                      dispersal is carried out by mammals.               included 10 traps, which were maintained
                      Their burrowing activities disturb the soil        for four consecutive evenings every 3-4
                      surface and open space for seedling                months.
                      establishment (Cox and Zedler 1986). In                Reference data.           At Tijuana
                      constructed and restored wetlands,                 Estuary, there were 114 captures and 8
                      herbivores can decimate transplants,               recaptures during the 7-month study
                      especially if the soil is not very wet or          (Table 10.1). Only three rodent species
                      tidal inundation is lacking. Ground                occurred in the marsh. These were the
                      squirrels and rabbits are probably the             western harvest mouse (Reithrodontomys
                      main grazers on transplants, and a pre-            megalods), the deer mouse (Peromyscus
                      planting survey of the project site would          maniculatus), and the house mouse (Mus
                      help determine if fencing or herbivore             musculus). Five additional species were
                      exclusion cages (Zedler 1984) will be              trapped in Goat Canyon, an upland area.
                      necessary. Additional studies are needed           The species list was extended with
                      to quantify mammal populations in                  evidence from sightings, scat, skeletons,
                      coastal wetlands and to determine their            and pellets.
                      unique roles in the ecosystem.
                          Methods. Small mammals are                         At Santa Margarita River Estuary,
                      trapped using Sherman traps. A con-                Hollis et al. (1988) and previous surveys
                      venient way to express the results is as           recorded 22 species. Hollis et al. (ibid.)
                                                                         found the highest number of species per
                      new captures per 100 trap nights. Mark-            habitat (9) in the maritime scrub habitat,
                      recapture methods provide more accurate            while the largest number trapped was in
                      estimates of population size than single           the willow woodland (Table 10.2).
                      trappings.                                         There were seasonal changes in numbers
                          At Tijuana Estuary, Taylor and                 trapped. Low numbers were associated
                      Tiszler (1989, unpub.) sampled small               with inlet closure and marsh flooding; in
                      mammals in seven habitat types, of which           1987, high densities in Feb. and May
                      four were in the salt marsh (Salicornia            were followed by low densities in
                                                                 i       August.
                      Salicornia / salt panne, salt panne, and
                      salt grass), and the remainder' in
                      peripheral habitats (border, upland,
                      upland transition). Each was sampled
                      monthly with 2 trapping grids. A grid
                      consisted of 10 Sherman traps located at
                      points 10 in apart in a 20-point grid.
                      Trapping was done from November
                      through May, for a total of 1440 traps.
                      Although animals were marked, the low
                      numbers of recaptures precluded density
                      estimates for any of the species.





                                                                   90





                        Sampling methods and comparative data from natural wetlands


                     Table 10.1. Mammals known from Santa Margarita River Estuary (SM; from Hollis et
                     al. 1988) and Tijuana Estuary (TE; Taylor, SDSU, unpub. data).

                                      Family               Common namo                    Scientific name

                     Marsupiala       Didelphiidae         Opossum                        Didelphis marsupialis             x     x
                     Insectivora      Soricidae            Ornate shrew                   Sorex ornatus                     x
                     Lagomorpha       Leporidae            Blacktail jackrabbit           Lepus californicus                x     x
                                      Audubon cottontail                                  Sylvilagus auduboni               x     x
                     Rodentia         Sciuridae            Calif. ground squirrel         Spermophilus beecheyi             x     x
                                      Geomyidae            Botta pocket gopher            Thomomys bottae                   x
                                      Heteromyidae         San Diego pocket mouse         Perognathusfallax                 x     x
                                                           Agile kangaroo rat             Dipodomys agilis                        x
                                      Cricetidae           Western harvest mouse          Reithrodontomys megalotis         x     x
                                                           Deer mouse                     Peromyscus maniculatus            x     x
                                                           Cactus mouse                   Peromyscus eremicus                     x
                                                           California mouse               Peromyscus cal#'ornicus           x
                                                           Brush mouse                    P. boy1ii .                       x     x
                                                           Desert wood rat                Neotoma lepida                    x
                                                           Dusky footed wood rat          N. fuscipes                       x
                                                           California meadow mouse        Microtus californicus             x     x
                                      Muridae              Norway rat                     Rattus norvegicus                 x
                                                           House mouse                    MUS musculus                      x     x
                     Carnivora        Procyonidae          Raccoon                        Procyon lotor                     x
                                      Mustilidae           Long-tailed weasel             Mustelafrenata                    x     x
                                                           Striped skunk                  Mephitis mephitis                       x
                                      Canidae              Coyote                         Canis latrans                           x
                     Artiodactyla     Cervidae             Mule deer                      Odocoileus hemionus               x


                     Table 10.2. Results of small mammal trapping at Santa Margarita River Estuary
                     (summarized from Hollis et al. 1988).

                     Uncommon s1mcies                            Ornate shrew                  Brush mouse
                          (averaged <5 new                       Botta pocket gopher           Desert wood rat
                          captures per 100 trap                  Pocket gopher                 Dusky-footed wood rat
                          nights in any habitat):                California mouse              Audubon's cottontail
                     Common Wecies:                              Western harvest mouse (WHM)
                                                                 Deer mouse (DM)
                                                                 California meadow mouse (CMM)
                                                                 House mouse (HM)

                     Mean new captures 12er 100 tW nights (by habitat Z=) for the 4 common Wecies:

                          Habitat                                    WHM             DM          CMM            HM

                          Dense Salicornia                           13.9            4.6          11.9          7.8
                          SalicornialDistichlis                        9.7           4.4          3.5           2.5
                          Salicornialsaltpan                           1.6         12.6           0.3           0.2
                          UplandlSalicornia                            9.5           9.4          1.6           4.1
                          Coastal strand                               3.3         19.5           0             5.0
                          Maritime scrub                               3.8         14.6           3.8           0.6
                          Cattails                                     4.3         18.6           7.7.          9.3
                          Willow woodland                              2.3         19.7           4.0           6.2




                                                                          91





                                                 Minimal Monitoring Program


                                                                          needed; 2 = desirable; 3 = worthwhile).
                        V. Recommendations                                It should be noted that our priority
                                                                          designations are tentative; as we come to
                                for minimum                               understand more about wetland
                                 monitoring                               ecosystem functioning, we are more able
                                                                          to select indicators of function. In the
                                                                          future, it may become clear that some
                          We recognize that most assessment               priority 3 variables are essential
                      and monitoring programs will be con-                measurements, or vice versa.
                      strained by funding and by the availability
                      of personnel who are qualified to sample                Sampling frequency. As dis-
                      such things as nitrogen fixation. Local             cussed earlier, ecosystem attributes differ
                      resource agencies have requested that we            in their temporal variability. Birds come
                      recommend minimal requirements for use              and go daily, and large changes occur
                      in setting permit conditions for wedand             with the fall and winter migratory
                      restoration or construction projects.               periods. In contrast, plant invasions or
                      Since the main purpose of monitoring is             local extinctions usually become obvious
                      to characterize the structure and                   only after a year or two. Thus, we
                      functioning of the metland, the sampling            recommend that some attributes be
                      program should be able to withstand the             measured as often as weekly, others
                      review of field ecologists. Thus, the               seasonally or annually, and some only
                      program should identify the habitats                after major events are noted.
                      being characterized; it should have
                      replicate sampling stations within each                 Not all wetlands will have the same
                      habitat; and it should provide data that            temporal variability,, so it is difficult to
                      document ecologically meaningful                    suggest a single program that can fit all
                      changes when they occur. General                    systems. Soil salinities, for example,
                      analyses of the data should indicate that           will* show greater extremes and more
                      the sampling program is encountering the            sudden changes in lagoon wetlands (often
                      bulk of the species present, and that               nontidal) than in fully tidal marshes.
                      variances among replicate sampling                  Monitoring programs should be tailored
                      stations are not excessively high. The              to the needs of the system being
                      recent text on "Ecological Methodology"'            monitored, beginning with frequent
                      (Krebs 1989) provides further discussion            measurements and reducing sampling if
                      of these issues.                                    experience suggests that reducing the
                                                                          frequency will not'significantly reduce
                          Monitoring programs can be                      information about the system. Monitors
                      expanded or reduced in different ways,              should be prepared to increase sampling
                      by varying the number of attributes exam-           frequency in response to events such as
                      ined, the frequency of examination, and             floods, wastewater spills, algal blooms,
                      the number of sampling stations.                    or inlet closure.
                      Additional cuts or additions could include
                      the detail of examination within sampling               Numbers of sampling stations.
                      stations (e.g., depths at which soil                Field monitoring programs should
                      salinity is measured) and back at the               provide an adequate sample of the area to
                      laboratory (e.g., determination of inver-           which results will be generalized.
                      tebrates to family or to species; chemical          Experienced field ecologists can usually
                      analysis of pooled or individual soil               walk through a site and delimit habitat
                      samples from each sampling station).                areas that are "relatively homogeneous,"
                                                                          but aerial photos are a great aid. Within
                         Priority attributes. The attributes              each habitat area, replicate samples are
                      can be prioritized based on what we need            taken at no fewer than three stations.
                      to know and how much information is                 Initial sampling will provide estimates of
                      provided by -the data (priority I = most            heterogeneity (variance of each attribute


                                                                    92





                                           Minimal Monitoring Program


                measured); if initial replicate stations give        should the monitoring period include
                high variance (e.g., if the standard error           years of unusual events. Such was the
                exceeds 10% of the mean), additional                 case at Tijuana Estuary, where salt marsh
                replicate samples are needed to                      monitoring began in 1979, two major
                characterize the attribute adequately.               floods occurred in winter 1980,
                Because the system's variability dictates            prolonged flooding occurred through
                the number of replicate samples needed,              April 1983, the tidal inlet closed for 8
                we cannot prescribe the number of                    months in 1984, and raw sewage inflows
                sampling stations needed. Our advice is              became substantial and continuous in
                to plan for a large number of replicate              about 1986.
                stations and cut back if variances are low.
                Krebs (1989) discusses the numbers of                    Long-term monitoring allows one to
                replicate samples needed to provide                  distinguish directional changes (e.g.,
                ecologically meaningful data. Results can            expansion of cordgrass, declines of
                be summarized to test for differences                endangered bird populations) from short-
                between different locations (e.g., restored          term shifts (e.g., annual variability in
                and natural wetlands) or differences with            shorebird use). Permits for projects in
                time (e.g., year-to-year changes).                   wetlands sometimes require 20 years of
                                                                     monitoring (Phil Williams, Phil Williams
                    An alternative approach to replicate             Assoc., San Francisco, pers. comm.) and
                sampling within habitat areas is                     often require up to 10 years of
                appropriate where gradients of                       assessment (with annual measures in the
                environmental conditions are present.                earlier years).
                For estuarine channels that range from
                high salinity at the inlet to low salinity               Paul Zedler analyzed San Diego
                inland, it is more useful to position                rainfall data as a measure of the variability
                sampling stations along the gradient and             of vernal pool environments (Zedler and
                to plot water quality characteristics                Black 1989). For the 138 years of
                against distance. Instead of clumping                record, the range was 57 cm, which is
                sampling stations within homogeneous                 about twice the average annual rainfall.
                sampling areas, one would distribute the             He calculated that monitoring would need
                stations at intervals proceeding upstream            to take place for 7-8 years just to include
                from the ocean inlet. Stations should be             half that range. Studies of 2-3 years
                closer together where environmental                  would typically cover only 20-30% of the
                changes are likely to be greatest. Results           historic range. Along a similar vein,
                can be summarized as graphs of each                  Westeby (in press) states, "Studies
                attribute against distance from inlet,               lasting 10-50 years do not provide
                looking for spatial trends and evidence of           enough replicate years to reliably detect
                shifts through time.                                 any but the strongest correlations between
                                                                     variables at one site, nor do they estimate
                    How long to      monitor. From the               frequencies of rare events very well."
                standpoint of the    biota, a twenty-year
                monitoring period is not unreasonable. It                Conclusion. Choosing a sampling
                may take even longer for the restored                program that can provide ecologically
                marsh to develop its full potential as               meaningful data through a ten-to-twenty-
                habitat for rare species, such as                    year period is not easy. Dozens of
                endangered birds. It may take longer for             decisions need to be made, and most
                the soil organic matter to increase to               require careful judgment based on
                natural levels. It may take longer for               preliminary data from the system in
                herbivory problems to become controlled              question. The assistance of experienced
                by native predators. Finally, for a region           field workers will be needed to tailor any
                that has highly variable rainfall, it may            11 generic monitoring program" to the
                take 20 years to characterize the mode, or           system in question.
                most usual condition of the wetland,


                                                               93





                                                         Minimal Monitoring Program


                            Table 4. 1. Priorities for wetland attributes to be monitored. Priority 1 = most needed.

                                                                                                          Frequency of
                            Attribute and measures                                    Priority             measurement

                            Hydrology
                                Salinity of water                                          1    monthly
                                Salinity of interstitial soil water                        I    seasonally (at least Apr. & Sept.)
                                Water levels at various fidal cycles                       2    spring tide cycle, e.g., in Nov.
                                Tidal flow rates at distances frDrn inlet                  3    spring tide cycle, e.g., in. Nov.
                            Topography
                                Elevation                                                  1    initially and after storms or floods
                                Slope of channel banks                                     3    initially; annually thereafter at
                                                                                                permanent cross-sections
                            Soils
                                Texture                                                    2    initially
                                Organic matter                                             1    pre-planting; plan for amendments
                                Toxic substances                                           3    pre-dredging; costly analysis
                                Redox potential                                            2    useful in diagnosing cause of
                                                                                                   plant mortality
                                Sulfides and pH                                            3    redox potential is easier
                            Nutrient dynamics
                                Nitrogen fixation rates                                    3    seasonal, as research study
                                Inorganic nitrogen in sediments and pore water             1    initially to plan for amendments;
                                                                                                   repeat if plant growth is poor
                                Litter decomposition                                       3    seasonal, as research study
                                Nitrogen mineralization rates                              3    seasonal, as research study
                                Foliar nitrogen of dominant plant species                  2    annually in September
                            Algae
                                Cover by dominant type                                     1    monthly with salinity samples
                            Vascular plants
                                Aerial photos of plant cover and habitat types             I    annually
                                Heights and total stem length of cordgrass                 1    annually in September
                                Cover of vascular plants                                   1    annually in September
                                Patch size of rare annual plants                           1    annually in spring
                                Density of annual plants                                   3    annually in spring
                            Consumers
                                Decomposers and shredders                                  3    seasonal, as research study
                                Aquatic insects                                            2    seasonally
                                Terrestrial insects,                                       3    seasonal, as research study
                                    especially pollinators                                 I    important where annual plants are
                                                                                                   required; census in spring
                                    and predatory insects                                  1    important where insect
                                                                                                   herbivory is obvious; census in
                                                                                                   warm season (May-Oct.)
                                Fishes                                                     1    at least in June and September
                                Benthic invertebrates                                      I    seasonally
                                Birds                                                      I    weekly in fall-spring;
                                                                                                   biweekly in summer
                                Reptiles and amphibians                                    '3   summer
                                Mammals                                                    3    (high priority in regions with
                                                                                                   salt marsh harvest mouse)




                                                                            94





                                          Minimal Monitoring Program


                Table 4.2. A minimum monitoring program for a wetland with aquatic and marsh habitats.

                                                       Before            Annual monitoring schedule
                                                        Mj       J F M A M J J A S 0 N D
                Hydrology
                    Salinity of water                            x x     x x x x x x x x x x
                    Salinity of interstitial
                        soil water                               x          x           x       x
                Topography
                    Elevation                            x       and after storms or floods
                Soils
                    Organic matter                       x       repeat 2-3 months after any soil amendments
                Nutrient. dynamics
                    Inorganic nitrogen in sediments
                        and pore water                   x       repeat 2-3 months after any soil amendments
                Algae
                    Cover by dominant type                       x x x x x x x x x x x x
                Vascular plants                                                             x
                    Aerial photo analysis
                    Heights and total stem length
                       of cordgrass                                                             x
                    Cover of vascular plants                                                    x
                    Patch size of. rare annual plants                       x
                Consumers
                    Fishes                                       x          x           x       x
                    Benthic invertebrates                               x           x           x            x
                    Birds                                W WWWWB B                      B B     WWW

                X = sample once during month;            x = sample to omit if funds are insufficient;
                W = sample weekly through month;         B = sample biweekly.























                                                              95






                                                              Literature cited


                                                                                 their possible relationships with the
                                 Literature cited                                latitudinal distribution of shorebird
                                                                                 species. M.S. Thesis. San Diego
                                                                                 State University. San Diego. 78 p.
                         Adamus, P. R., and L. T. Stockwell                  Boland, J. 1988. The ecology of North
                             1983. A method for wetland func-                    American shorebirds: Latitudinal dis-
                             tional assessment, Vol. 1. Federal                  tributions, community structure, for-
                             Highway Administration Report No.                   aging behaviors, and interspecific
                             WWA-EP-82-23. U.S. Department                       competition. Ph.D. Dissertation.
                             of Transportation. Washington, D.C.                 University of California.            Los
                                                                                 Angeles. 256 p.
                         Adamus, P. R., E. J. Clairain, Jr., R. D.           Broome, S.W. 1987. Creation and
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