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












                                 PB95-192191                                              Wwwzd= tz azw 4a.:,"Juza.



                              INDICATOR DEVELOPMENT: SEAGRASS                             MONXTORING
                              AND RESEARCH IN THE GULF OF MEXICO. REPORT
                              OF A WORKSHOP. HELD                   IN SARASOTA, FLORIDA ON
                              JANUARY 28-29, 1992











                            .(U.S.) NATIONAL BIOLOGICAL SURVEY, LAFAYETTE, LA





                             DEC 94





                                                                   .In%



              SH393
               U55
              153
              1994



                              U.S. DEPARTMENT OF COMMERCE
                              National Technical information Service















                                                                              TECHNICAL REPORT DATA
                                                         (PL     READ INSTRUCTIONS ON THE REVERSEREFOF

                           1. REPORT NO                         2                                        3. P
                                        EPA620R94029                                                                 PE95-192191
                           4. TITLE AND SUBTITLE                                                         5, REPORT DATE  December 1994

                           indicator Development: Seagrass Monitoring and Resea-ch in the Gulf of Mexico 6. PERFORMING ORGANIZATION CODE



                           7. AUTHOR(S)                                                                  8. PERFORMING ORGANIZATION REPORT NO

                           Npckles. H. A. (ad.) 1994. National Biological Survey






                           9, PERFORMING ORGANIZATION NAME AND ADDRESS                                   10. PRO(3RAM ELEMENT NO.

                           U.S. Environmental Protection Agency, Office of Research and Development.     11. CONTRACT/GFIANT NO.
                            Environmental Research Laboratory. Gulf Breeze. FL 32561                     DW 14936928-01-0




                           12. SPONSORING AGENCY NAME AND ADDRESS                                        13. TYPE OF REPORT AND PERIOD COVERED

                            U.S, ENVIRONMENTAL PROTECTION AGENCY
                            ENVIRONMENTAL RESEARCH LABORATORY                                            14, SPONSORING AGENCY CODE
                            OFFICE OF RESEARCH AND DEVELOPMENT
                            GULF BREEZE. FLORIDA 32561


                           15. SUPPLEMENTARY NOTES

                           This document is a final report of a workshop co-sponsored by U.S. EPA EMAP-Estuaries. The National Biological Survey and
                           NOAA in 1992.

                           16. ABSTRACT.

                           Seagrass habitats in the Gulf of Mexico have declined precipitously during the past 50 years. Most habitat losses can be attributed
                           to effects of coastal population growth and accompanying municipal, industrial. and atjncuttural development. Although proximate
                           causes of local declines can sometimes be identified, the majority of habitat loss has resulted from widespread deterioration of water
                           quality. Restoration and preservation of these important habitats depend foremost on improving scientific understanding of the complex
                           causal relationships between anthropogenic stress and seagrass ecosystem persistence. and on developing scientifically based
                           management programs for seagrm conservation.
                           On January 28-29. 92. approximately 60 researchers, State and Federal regulators. and environmental managers met at Mote Marine
                                        ,@l . Florida. to address monitoring strategies, research programs and mapping of submerged aquatic vegetation
                           Laboratory in Sar
                           resources in the If of Mexico. This report summarizes the results of the workshops, emphasizing the recommendations of
                           participants in an attempt to guide del elopment of a comprehensive seagrass conservation program in the Gulf of Mexico.











                           IT KEY WORDS AND DOCUMENT ANALYSIS

                           A. DESCRIPTORS                       B. IDENTIFIEFIS/OPEN ENDED TERMS         C. COSATI FIELDIGROUP










                           16. DISTRISUT!ON STATEMENT           19. SECURITY CLASS (THIS REPORT)         21. NO. OF PAGES
                                                                UNCLASSIFIED                                               64
                                                                                                                           XX              59
                           RELEASE TO PUBLIC                    20- SECURITY CLASS (THIS PAGE)           22. PRICE
                                                                UNCLASSIFIED



                           EPA Form 2220-1 (Rev. 4EJ Previous Edition is Obsolete




















                                                                                                     PB95-192191
                                                                                                 EPA/620/R-94/029
                                                                                                   December 1994




                                                Indicator Development:

                                              Seagrass Monitoring and
                                          Research in the Gulf of Mexico

                                                 Report of a Workshop Held
                                                                at
                                                   Mote Marine Laboratory
                                                                in
                                                         Sarasota, FL

                                                    January 28-29, 1992,










                                                              Edited by
                                                           Hilary A. Neckles
                                                       National Biological Survey
                                                       Southern Science Center
                                                            Lafayette, LA
                       
                                                            Project Officer
                                                          J. Kevin Summers
                                                  US. Environmental Protection Agency  Property of CSC Library
                                                        EMAP-Estuaries
                                                                        Environmental Research Laboratory
                                                  Office of Research and Development
                                                                                     US Department of Commerce                                                                                                              						 NOAA Coastal Service Center Library	
													       2234 South Hobson Avenue
													       Charleston, SC 29405-2413
									U.S. Environmental Protection Agency
                                                        Gulf Breeze, FL 32567                                                                                                                                          


                                                                                              Printed on Recycled Paper
 












                                                                       DISCLAIMER



                                        This document has been reviewed in accordance with U.S. EnvironmenLil Protection Agency
                                        policy and approved for publication. Mention oftra(le names or cominercial prodUCLs dix@s not
                                        constitute endorsement or recommendation for uw.
















                                                                                                                                                   OF




























                             Seagrass Monitoring and Research - 1992                                                        Page iii


								PREFACE

	This document is a final report of a workshop co-sponsored by U.S. EPA, EMAP-Estuaries. The National
	Biological Survey and NOAA in 1992.

	The appropriate citation for this report is:

	Neckles, H.A.(ed.) 1994. Indicator Development: Seagrass Monitoring and Research in the Gulf of 
	Mexico. U.S. Environmental Protection Agency. Office of Research and Development, Environmental 
	Research Laboratory, Gulf Breeze, FL. EPA/620/R-94/029.

























                                Seagrass Monitoring and Research-1992						Page iv
 

							ACKNOWLEDGMENTS


This workshop was sponsored by the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, and the
National Oceanic and Atmospheric Administration. We thank the scientists and resource managers who participated in the
workshop and whose ideas and discussions form the basis of this report. We are especially grateful to Mike Durako, Ken
Haddad, and Chris Onuf for leading working groups on research, mapping, and monitoring: to Ernie Estevez, Mark Fonseca,
Ken Moore, and Judy Stout for leading working groups on conservation objectives to Julie Morris for assisting with 
workshop organization and for facilitating all discussions: and to Bill Dennison for chairing the plenary sessions and 
finding the common threads among working group reports. Kumar Mahadevan and the staff of Mote Marine Laboratory graciously
hosted the workshop and provided on-site support critical to workshop success, and Martha Griffis, Lois Haseltine, and
Cam Wiik assisted in preparation of this report.

Workshop Steering Committee:

Hilary A. Neckles, National Biological Survey
W. Judson Kenworth, National Marine Fisheries Service
William L. Kruczynski, U.S. Environmental Protection Agency
J. Kevin Summers, U.S. Environmental Agency




















			Seagrass Monitoring and Research-1992							Page v

								WORKSHOP PARTICIPANTS



	Susan S. Bell, Ph.D.,University of South Florida, Tampa, Fl.
	Douglas A. Bulthuis, Ph.D.,Padilla Bay National Estuarine Research Reserve, Mt. Vernon, WA
	Otto S. Bundy, Horticulture Systems, Inc.,Parrish, FL
	JoAnn M. Burkholder, Ph.D.,North Carolina State University, Raleigh, NC
	Paul R. Carlson, Jr.,Ph.D.,Florida Department of Natural Resources, St. Petersburg, FL
	James K. Culter, Mote Marine Laboratory, Sarasota, FL
	Clinton J. Daws, Ph.D.,University of South Florida, Tampa,FL
	Robert Day, Indian River Lagoon National Estuary Program, Melbourne, FL
	William C. Dennison, Ph.D.,University of Queensland, St. Lucia, Qld.,Australia
	L. Kellie Dixon, Mote Marine Laboratory, Sarasota,Fl.
	Kenneth W. Dunton, Ph.D.,University of Texas at Austin, Marine Science Institute, Port Arkansas, TX
	Michael J. Durako, Ph.D.,Florida Department of Natural Resources, St. Petersburg,FL
	Lionel N. Eleuterius, Ph.D.,Gulf Coast Research Laboratory, Ocean Springs, MS
	Ernest D. Estevez, Ph.D.,Mote Marine Laboratory, Sarasota, FL
	Randolph L. Ferguson, Ph.D.,National Marine Fisheries Service Laboratory, Beaufort, NC
	David A. Flemer, Ph.D.,U.S. Environmental Protection Agency-Environmental Research Laboratory,Sabine Island, Gulf 
	Breeze, FL
	Ruth Folit, New College Environmental Studies, Sarasota,FL
	Mark S. Fonseca, National Marine Fisheries Service Laboratory, Beaufort,NC
	Charles I. Gallegos, Ph.D.,Smithsoniar, Environmental Research Center, Edgewater, MD
	Holly S. Greening, Tampa Bay National Estuary Program, St. Petersburg, FL
	Ken D. Haddad, Florida Department of Natural Resources, St. Petersburg,Fl
	Margaret O. Hall, Ph.D.,Florida Department of Natural Resources, St. Petersburg, FL
	Lawrence R. Handley, National Biological Survey, Southern Science Center, Lafayette, LA
	M. Dennis Hanisak, Ph.D.,Harbor Branch Oceanographic Institute, Ft. Pierce, FL
	Kenneth I. Heck.,Jr.,Ph.D.,Dauphin Island Sea Laboratory, Dauphin Island,AL
	Jeff G. Holmquist, Ph.D.,University of Puerto Rico, Lajas PR
	Roger Johansson, City of Tampa, Tampa,FL
	James B. Johnson, Ph.D.,National Biological Survey, Southern Science Center, Lafayette, LA
	W. Judson Kenworthy, Ph.D., National Marine Fisheries Service Laboratory, Beaufort,NC
	William L. Kruczynski, Ph.D.,U.S. Environmental Protection Agency-Environmental Research 
	Laboratory, Sabine Island, Gulf Breeze, FL
	Brian E. Lapointe, Ph.D.,Harbor Branch Oceanographic Institute, Big Pine Key, FL
	Lynn W. Lefebvre, Ph.D.,U.S. Fish and Wildlife Service, Gainesville, FL
	Jay Leverone, Mote Marine Laboratory, Sarasota, FL
	Helene Marsh, Ph.D.,James Cook University, Townville,Qld.,Australia
	Mike J. Marshall, Ph.D.,Mote Marine Laboratory, Sarasota, FL
	Peggy H. Mathews, Department of Environmental Regulation, Tallahassee,FL
	John M. Macauley, U.S. Environmental Protection Agency-Environmental Research Laboratory.
	Sabine Island, Gulf Breeze, FL
	Benjamime F. McPherson, Ph.D.,U.S. Geological Survey, Tampa,FL


	Seagrass Monitoring and Research-1992								Page vi
















                       Kenneth A. Moore. College of William and Mary. Virginia Institute (if N4arine Science.
                        Gloucester Point, VA
                       Julie Morris. New College Fnvironmental Studies. Sarasota. 11.
                       Hilary A. Neckles, Ph.D.. National Biological Survey, Southern Science Center.
                        Lafayette. LA
                       Walter Nelson. Ph.D.. Florida Institute of Technology, Melhoume. 11.
                       John C. Ogden. Ph.D.. Florida Institute of Oceanography, St. Petersburg. 11.
                       Christopher P. Onuf, Ph.D.. National Biological Survey. Corpus Christi. TX
                       Robert J. Orth, Ph.D., College of William and Mary, Virginia Institute of Marine Science.
                        Gloucester Point, VA
                       Ronald C. Phillips. Ph.D.. Battelle, Pacific Northwest Laboratories, Richland. WA
                       Warren M. Pulich. Jr.. Ph.D., Texas Department of Parks and Wildlife. Austin.TX
                       Thomas F. Ries. Southwest Florida Water Management District. Tampa. 1-1.
                       Frederick T. Shon. Ph.D.. Univeisity of New Hampshire. Jackson Estuarine Laboratory. Durham. NH
                       Kenneth N. Smith, Florida Department of Natural Resources, Tallahassee, 17L                                                OF
                       Judy P. Stout. Ph.D.. Dauphin Island Sea Laboratory. Dauphin Island. Al-
                       Michael J. Sullivan, Ph.D.. Mississippi State University. Mississippi Stale. MS -
                       J. Kevin Summers, Ph.D.. U.S. Environmental Protection Agency-Environmental Research LaNiratory.
                        Sabine Island. Gulf Breeze. F-L
                       John Thompson. Continental Shelf Associates, Jupiter. T-T.
                       David A. Tomasko. Ph.D., Sarasota Bay National Estuary Program. Sarasota. FL
                       Dean A. Ullock, U.S. Environmental Protection Agency. Coastal Programs Section, Atlanta. GA
                       Robert W. Virnsein. Ph.D., St. Johns River Water Management District. Palatka. F1,
                       Pichard L. Wetzel, Ph.D., College of William and Mary. Virginia Institute of Marine Science.
                        Gloucester Point. VA
                       Susan L. Williams, Ph.D., San Diego State University, San Diego, CA
                       Joseph C. Zieman. Ph.D., University of Virgipia. Charlottesville. VA
                       Richard C. Zimmerman, Ph.D.. University of California. Los Angeles. CA





















                       Seagrass Monitoring and Research - 1992                                                      Page vii
















                                                            TABLE OF CONTENTS



                        DISCLAIMER            ........................................... I ................................    iii

                        PREFACE               .........................   .................................................     iv


                        ACKNOWLEDGMENTS           ....................................................................... .


                        WORKSHOP PARTICIPANTS                                                               .........           V,


                        INTRODUCTION          ...........................................................................       9

                        RECOMMENDATIONS           ........................................................................      11


                        BACKGROUND FOR RECOMMENDATIONS: WORKSHOP PRESENTATIONS AND
                        DELIBEICATIONS        ...........................................................................       15


                        CONSERVATION AND RESTORATION OFTHE SEAGRASSES                    OFTHE GLI-F OFMEXICO
                        THROUGH A BETTER UNDERSTANDING OF THEIR MINIMUM LIGHT REQUIR1.MENTS
                        AND FACTORS CONTROLLING WATER TRANSPARENCY                                                              17
                        W. Judson Kenworshy
                        SUBMERGED AQUATIC VEGETATION MAPPING                  ...............................................   33
                        Lawrence R. Handley


                        ECOLOGICAL INDICATORS           .........................................................     ........  43
                        Hilary A. Neckles

                        SUBMERGED AQUATIC VEGETATION RESEARCH NEEDS                    ................ ...............         St.
                        %iffiam I- Krucqnski
                        SEAGIUSS CONSERVATION IN THE GULF OF MEXICO: AN ACTION AGENDA                            .............. 59
                        'Hilary A. Neckles           @ I .   I                 -                      . I                I.

                        APPENDIX A            ..............................................     ............................   63















                        Seagrass Monitoring and Research - 1992                                                       Page viii











                                                                  INTRODUCTION



                        Scagrass habitats in the Gulf ol'Mexico have                    IMAP-Estuaries is designed to characterize th,.:
                        declined precipitously during ihe past 50 years.                ecological conditior (if the nation's estuarine and
                        Most habitat losses can he attributed to    c flects of         coastal resources over broad geographic regions
                        coastal population growth and accompanying                      and long linic [wriods. The program is intended
                        municipal. industrial. and agricultural                         to provide quantitative information on the extent
                        development. Although proximate causes of                       and potential causes ofadverse environmental
                        local declines can sometimes he idenlified. t'ie                changes. In an effort to provide one indicator (if
                        maJority of habitat loss has resulted from                      nearsh(ire environnicnial quality, I:NIAI'-
                        widespread deleriorafion of water quality.                      Fstuaries is mapping the location and extent of
                        Restoration and preservation (if these important                SAV in Lhe coastal region of the Gulf (if Mexico.
                        habitats depend foremost on improving scientific                All maps are scheduled to he completed in 1995.
                        understanding of the complex causal                             Baseline information on !be distribution and
                        relationships between an1hropogenic stress and                  abundance of SAV will     ,then he used to devc1op a
                        seagrass ecosystem persistence, and on                          monitonng program to assess the status and
                        developing scientifically based management                      trends of these hahitats. This assessment will he
                        programs for seagrass conservation.                             based on measurement of defined parameters
                                                                                        that serve as indicators of SAV hahitai quality.
                        On January 28-29'. 1992, approximately 60                       The workshop developed recommendations for
                        researchers. State and Federal regulators, and                  SAV mapping. classification. and monitoring in
                        environmental managers met at Mote Marine                       the Gulf of Mexico. and identified a set of
                        Laboratory in Sarasota. Flotida, to discuss                     ecological indicators for accurate assessment of
                        strategies for monitoring the environmental                     SAV habitat condition.
                        status of seagrass hahitats and to determine the
                        research needed it) increase our knowledge of                   The FTA Wetlands Research Program included
                        wagrass responses to anthropogenic stress. The                  funding in 1992 for the initiation (if coastal
                        workshop was sponsored by the U.S.                              wetlands research. The EPA Science Advisory
                        F.rivironmental protection Agency 0:11A). the                   Board recommended that initial research he
                        U.S. Fish and Wildlife Service. and the National                conducted on the effects (if cumulative impacts
                        Oceanic and Atmospheric Administration. The                     within watersheds on coastal SAV communities.
                        goals of the workshop were to provide technical                 The workshop identified and prioritized research
                        guidance (in monitoring requirements to the                     needs to develop a pilot project and a future F.PA
                        F.PA's Environmental Monitoring and                             Coastal Wetlands Research Initiative on a
                        Assessment Program- F.stuaries and it) assist in                national %Late. As a result of this workshop a
                        the development of a coastal wetlands research                  study of seagrass responses to long-temi light
                        program at the EPA's Environmental Research                     limitation was initiated at three field sites in the
                        Laboratory-Gulf Breeze. In addition. the                        Gulf of Mexico.
                        workshop provided a forum for coordinating
                        research and monitoring activities among                        Following introductory presentations (in FMAP.
                        government agencies. universifies. and private                  the Wetlands Research Program, and the state of
                        organizations with interest and mandates in the                 current knowledge of seagra-s-s environmental
                        protection (if submerged aquatic vegetation                     requirements. workshop participants divided into
                        (SAV) resources in the Gulf of Mexico.                          three working groups to address Lhe workshop


                        Seagrass Monitoring and Research - 1992                                                                    Page 9-















                          objectives: seagrass mapping, ecological
                          indicators. and research needs. At the@end of the
                          workshop, participants reorganized into four
                          working groups. each charged with developing a
                          list of the highest priority actions Ifor
                          preservation and restoration of seagrass systems.
                          The working groups reconvened periodically in
                          plenary sessions to report conclusions. solicit
                          input from other workshop participarts, and to
                          integrate and synthesize recommendations. This
                          report summarizes results of the workshop.
                          emphasizing the recommendations of
                          ,participants in an attempt to guide development
                          ,)f a comprehensive seagrass conservation
                          program in the Gulf of Mexico.'



































                          Seagrass Monitoring and Research - I M                                                           Page 10












                                                         RECOMMENDATIONS


                       Knowledge of seagrass systems and our ability                 within geomorphic sirata a second tier of
                       to preserve and restore these important habitats              sampling stratillication should be introduced.
                       will he advanced most effectively through the                 based (in bed size, water depth. and sufficial
                       integration of mapping, monitoring. and research              sediment type.
                       across a range of spatial and temporal scales
                       (Fig. 1). Specific recommendations within each                Mapping of the Louisianan Province should twe
                       of these components., of a comprehensive                      repeated every four years to assist other SAV
                       seagrass conservation program are listed below.               monitoring. to ensure the repeatability of sample
                                                                                     locations, and to establish long-term trends in
                                                                                     SAV disLributi(,.n and abundaice.
                       MAPPING
                                                                                     ECOLOGICAL INDICATORS
                       All maps should be produced at a scale of
                       1:24,000 to conform to the standard of U.S.                   Various parameters reflecting SAV responses to
                       Geological Survey topographic quadrangles.                    environmental stressors can he mc-Mured to
                                                                                     quantify the ecological condition (if the habitat.
                       Maps should be developed from aerial                          Response indicators fall into three classes.
                       photographs combined with extensive concurrent                according to their readiness for incorporation
                       field ground-truthing. A minimum list of ground               into a long-term monitoring program:
                       data to verify photointerpretafion includes
                       submerged aquatic vegetation (SAV) species                    0 Parameters that are ready for implementation
                       present, confirmation of the signature                             macrop6yte depth lim't, shoot density.
                       identification, nonvegetated features, and                       aboveground and belowground biomass.
                       location. Other data that can be collected during                species composition of SAV and macroalgae.
                       ground truthing yet are not critical to map
                       verification may either assist in                             0  Parameters for which field evaluations are
                       photointcrpretation or make the map more                         necessary to define temporal and spatial
                       useful. These data include SAV density, water                    variability and to furtkr characterize
                       depth, presence or abundance of epiphytes and                    relationships to multiple environmental
                       macroalgae, evidence of prop scars, sediment                     stressors - algal biomass. leaf -width. plant
                       type, turbidity, and salinity.                                   constituents, stress proteins, grazer densities;

                       Global Positioning System technology should be                0  Parameters dependent on newly available
                                                                                        technologies that with. significant additional
                       used whenever possible during routine collection
                       of SAV field data to provide true locations for                  developmem. might be important future
                       correlation with historical, present. and future                 ecological response indicators - leaf area
                       maps.                                                            index measured with an aulomatic meter and
                                                                                        genetic diversity using DNA fingerprinting.
                       SAV beds should be stratified for Environmental
                       Monitoring and Assessment Program (EMAP)
                       sampling based on gcomorphic type: hypersaline
                       lagoons, estuaries, open coastal, and deltaic
                       formations. To ensure equal representation

                     'S..@-agrass Monitorini and Research - 1992                                                              Page 11






















                                Centimeters 40                   SPACE               No. Kilom  .e
                                         Days oN                 TIME                Do- D e c a d e
                                   Molecule.s v4             COMPLEXITY              -o-Ecosyst






                                  A(-






                         3














                                 
None of the proposed response indicators have been tested at the regional and decadal scales used by EMAP. Seagrass beds are dynamic, comples systems, and many of the parameters used to characterize habitat condition, therefore, exhibit considerable, temporal and spatial variability.  We recommend strongly that the EMAP network be supplemented with increased sample density at selected sites.  The ability to detect change from widely spaced samples taken annually must be validated before meaningful statistical confidence can be placed in the use of the proposed indicators to assess regional longterm trends in seagrass ecosystem health.
The most important parameters to measure as indicators of the extent of pollutant exposure or habitat degradation present in Gulf of Mexico seagrass systems are water column light attenuation, turbidity, chlorophyll concentrations, dissolved nutrient concentrations, and diet fluctuation in dissolved oxygen concentrations.  All of these exposure indicator sexhibit extremee temporal variability, so that single, annual samples would yield no useful information.  To provide the needed data, exposure indicators must be evaluated either from frequent sampling or from continuous monitoring at permanent stations.
Although the proposed indicators exhibit general relationships with habitat quality, threshold values separating desirable conditions from undesirable ones cannot be indentifgied for any of the variables.  Research is needed to better define and validate criteria for interpreting specific values of candidate response and exposure indicators in terms of ecosystem health.

RESEARCH NEEDS

Research is needed to determine the species specific minimum light requirements for long term persistence and restoration of subtropical seagrasses.

Assessment of the responses of seagrass communities to environmental stresses (e.g.. light quantity and quality, nutrients, sediment loading, salinity, temperature) is needed to betterh project the effects of environmental management strategies.  This area of research should examine potential changes in seagrass species, productivity, genetic diversity, and reproductive success in response to these parameters.  The roles of macroalgae and epiphytes in these changes and the potential complicating effects of plant-animal interactions should be evaluated.

Available mapls should be used as a research tool rather than simply as an assessment method.  Information on seagrwsss distribution and abundance should be used in correlative and other analyses to generate specific hypotheses on interrelationships among seagrass condition, depth, and other key forcing variables.

Very little is known about the environmental requirements of deepwater Halophila spp, communities.  This seagrass community requires significant general research to understand its role and importance in marine ecosystems.

CONSERVATION OBJECTIVES

No permitted losses of existing seagrass communities should be tolerated.  This is particularly important in the case of Thalassia beds, for which few examples of successful replacement have been documented.

Restoration of seagrasses to historical levels in the Gulf of Mexico will require widespread water quality improvements.  This required foremost that anthropogenic nutrient and sediment loading be reduced.

Legislative initiatives to protect and restore Gulf of Mexico seagrass communities depend ultimately on strong public support.  Public education programs should be developed to increase awareness of, and appreciation for, the 


Seagrass Monitoring and Research-1992									Page 13


 L












                              ecological and econon-tic values of scagrass
                              habitats.


                              A seagrass working group including research.
                              scientists, Federal. State. and local resource
                              managers. and representatives of user groups
                              should he formed to coordinate seagrass
                              conservation efforts in Lhe Gulf of Mexico.













































                             Seagrass Monitoring and Research - 1992                                                     Page 14
































                                   BACKGROUND FOR RECOMMENDATIONS:


                                       Workshop Presentations and Deliberatiou



















                      SejWrass MonilorLng and Research - 19L2                                       Pare 15




















                        CONSERVATION AND RESTORATION Of THE
                    SEAGRASSES OF THE GULF OF MEXICO THROUGH
                     A BETTER UNDERSTANDING OF THEIR MINIMUM
                             LIGHT REQUIREMENTS AND FACTORS
                            CONTROLLING WATER TRANSPARENCY


                                                           by


                                                  W. Judson Kenworthy

                                                   Beaufort Laboratory
                                     National Oceanic and Atmospheric Administration
                                             National Marine Fisheries Service
                                            Southeast Fisheries Science Center
                                                   Beaufort, NC 28516

















                  Seaems Monitoring and Research - 1992                                       Page 17


















                                                                               INTRODUCTION


                                .Spanning nearly 5 degrees of latitude and 15                    Halophila engelmanni (Fig. 2). Almost always
                                degrees of longitude, the Gulf of Mexico is the                  found growing completely submerged.
                                ninth largest tiody ol'water in the world. The                   seagrasses stabilize unconsolidated sediments
                                shallow coastal waters of the gulf consist of an                 and recycle nutrients while providing food,
                                assortment of physicochemical environment%                       shelter, and substrate for hundreds of species of
                                including extensive harrier island lagoons, 33                   flora and fauna (Durako et al. 1987. Zieman and
                                major river systems. and 207 estuaries. These                    Zierrian 1999). Despite the low diversity of
                                range from the clear subtropical carbonate                       species, seagrasses occupy a wide variety of
                                sediment-based systems of the Florida Keys to                    habitats including, but not restricted to. sand
                                the temperate hypcrsaline Laguna Madre -.n                       shoals. shallow muddy and sheltered lagoons.
                                Texas, The physical and chemical diversity                       high-energy tidal channels, and relatively deep
                                provided by these environments supports                          open-water continental shelves (Continental
                                extensive and highly productive plant                            Shelf Associates Inc. and Martel Laboratories
                                communities that are valuahlebabitats for                        Inc., 1985. Iverson and Bittaker 1986. Durako et
                                resident and migratory species of fish and,                      al. 1987. Zieman et al. 1989, Zieman and Zieman
                                wildlife. The Gulf of Mexico has the largest and                 1989). Their ability to grow in these very
                                most valuable shrimp fishery in the United States                different environments results from their
                                as well as numerous other important commercial                   phenotypic plasticity and the wide diversity of
                                and recreational fisheries. many of which depend                 morphology and life history strategies provided
                                on the shallow vegetated ecosystems fringing the                 by a remarkably few species. Size alone
                                gulf.                                                            illustrates the heterogeneity fumished by the
                                                                                                 limited species pool. Fully mature seagrass
                                The Gulf of Mexico is experiencing the second                    communities in the Gulf of Mexico span two
                                fastesi rate of growth of the five coastal regions               orders of magnitude in canopy height and
                                of the Uni'@d States. Most growth and                            belowground structure and three orders of
                                development are occuffirig within a few miles of                 magnitude in weight. from the small low-relief
                                the shoreline or along the watersheds draining                   meadows of Halophila decoiens and Halophila
                                into the gulf. Two-thirds of the land area of the                engelmanni up to the robust and dense beds of T
                                contiguous United States eventually drains into                  testudinum (Zieman and Wetzel 1980). In
                                the Gulf of Mexico. delivering organic matter,                   between these extremes are two conspicuous
                                inorganic nutrients. and fresh water. Unless                     plants. Halodule wrightii and S. fififorme, which
                                growth and water quality are properly managed,                   are intermediate in size and reproduce
                                the consequences are a predictable                               vegetatively at a moderately high rate (Eleuterius
                                environmental degradation and a serious threat                   1987, Fonseca et al. 1987).
                                to the health and well-being of the coastal living
                                marine resources.                                                Our understanding of the role seagrasses have in
                                                                                                 supporting the living marine resources
                                Seagrasses are an important component of the                     of the Gulf of Mexico. and our ability to predict
                                coastal plant communities in the Gulf of Mexico                  what the effects of altered water quality will have
                                (Durako et al. 1987. Zieman and Zieman 1989).                    on these functions, depend on a comprehensive
                                Four genera, including rive of the six tropical                  understanding of the mechanisms controlling
                                western hemisphere species. grow in the gulf                     their distribution and abundance. Li ht,
                                                                                                                                     ,    V-1
                                Thalassia testu&num. Syringodiumfififorme.                                     sqbsLrate, nutrients, and water
                                Halodule wrighdi, Halophila decipiens. and                       motion constitute _Lhe - m_a__ jor e-n-v-irorunental


                                Sea,arass Monitoring and Research - 1992                                                                   Page 18









            A-














                                                                                                                         A.,

                                                                                                        Halophila decipie'ns






                                                                     ,H,Vwsd,- wrighdi


                                                                                                                 llalophiw engeL.Mm





                                                                              ,pi











                                                                              UsAmfinson




                                                      F%ore 2. Mustration of Uw Bve specks of sub-frop" and troocal sengrams towW growbig In
                                                      tbe Gulf of Mexico (hvm Fonseca, 1"3@ Horlzontml ban   I an scalt.













                              Seajerms Monitoring and Researrh - 1992                                                                          Page 19


factors controlling seagrass growth.  Of these five parameters, light is the most important. The quality and quantity of available photosynthetically active radiation (PAR: 400-700 nm) drive the photosynthetic processes to fix darbon and produce oxygen, two metabolic processes critical for the survival and growth of seagrasses.  Ultimately, the amount of light reaching seagrasses depends on water transparency, which is a function of the water quality parameters that influence light alltenuation in the water column and on the surfaces of the leaves (Neckles 1991, Morris and Tomasko 1993).

In general, it is difficult to assign overall dominance or abundance to any one of the five species in the Gulf of Mexico.  A real distribution is patchy and, depending on the location, relative abundance of species will shift within a few meters.  In spite of this variability, consistent patterns of depth distribution provide evidence for the interrelationships between seagrasses and water quality, particularly water transparency (Iverson and Bittaker 1986, Dennison 1987, Durako et al. 1987. Zieman and Zieman 1989, Duarte 1991, Kenworthy and Haunert 1991, Morris and Tomasko 1993).  The observed patterns suggest tha tthe five species can be collapsed into three groups with different minimum light requirements...In descending order from highest to lowest-light-requirements they are 1) T. testudinum, 2) Halodule wrightii/S. filiforme, and 3) Halophila decipiens/Halophila englemanni.

SEAGRASS MINIMUM LIGHT REQUIREMENTS

Two by products of photosynthesis, carbohydrates and oxygen, form the basis of two working hypotheses seeking to explain the mechanisms controlling the distribution of seagrasses (Dennison and Alberte 1986, Marsh et al. 1986, Dennison 1987, Smith et al. 1988.

Zimmerman et al. 1989.  Zimmerman et al. 1991. Morris and Tomasko 1993). Carbon fixed in photosynthesis i sused to build nonstructural carbohydrates, which support maintenance respiration, and structural carbohydrates, which support new growth (carbon balance: Zimmerman et al. 1989).  Oxygen produced in photosynthesis is critical to the metabolic needs of the roots and rhizomes of seagrasses, which often grow in chronically anoxic sediments and are exposed to the potentially toxic effects of reduced sulfur compounds (Penhale and Wetzel 1983, Smith et al. 1984, Smith et al, 1988).  Carbon balance and oxygen production are not necessarily competing hypotheses, yet they may operate to different degrees in affecting seagrass distribution, depending on the available species pool and the prevailing submarine light regime.

Recent studies have indicated that the minimum light requirements of seagrasses growing in the Gulf of Mexico are much higher than originally suggested by physiological studies of leaf photosynthesis alone (Vincente and Rivera 1982, Onuf 1991, Furquerean 1991, Fourquerear and Zieman 1991, Kenworthy and Haunert 1991, Kenworthy 1992, Morris and tomasko 1993).  The traditional definition of the light compensation point (I0, which historically has been 1-5% of the surface incident light, may be appropirate for phytoplanktom, marcroalgae, and charophytes, but it underestimates the requirements of many seagrasses, including those residing in the Gulf of Mexico (Dennison 1987, 1991, Duarte 1991, Kenworthy and Haunert, 1991).

Whole plant minimum light requirements, rather than the requirement of leaves alone, define an ecological light compensation point (sensu Goldsborough and Kemp 1988) estimated to be approximately 15-20% of the average annual surface incident light for Halodule wrightii and S. filiforme (Onuf 1991, Kenworthy et al. 1991, Morris and Tomasko 1993).  Because of the extensive belowground storage mass of T. testudinum (Dawes 1987, Fourquerean and


Seagrass Monitoring and Research-1992								Page 20














                        heman 199 1), this species may be capable of                199 1. Kenworthy 1992). Thereforc. Halodule
                        withstanding periods of reduced light (Hall et al..         wrightii can sustain growth al lower light levels
                        199 1). During periods of low light. carbohydrate           for longer periods (if time than can T testudinurn
                        reserves may be diverted from the rhizomes to               and will survive in deeper water as well as water
                        support whole plant carbon balance (Tomaiko                 with lower overall transparency fa lower
                        and Dawes 1989). The ability to utilize   . reserves        minimum light requirement).
                        may depend on the previous light history of the
                        plant. During periods of light stress, carbon               This comparison. and the emerging general
                        reserves may become depletcd more rapidly in                understanding of the minimum light
                        species like Halodule wrighiii and S. filiforme             requirements of seagrasses. suggest that we may
                        that have less belowground storage capability               be able to predict what species should be
                        than does T testu&num. Thalassia testudinum                 growing under different conditions of water
                        may be better adapted to avoid short-term                   transparency as well as the maximum depth and
                        deficiencies in carbon balance, however,                    overall areal coverage we should expect in a
                        observations of depth distribution suggest that             particular water body. This predictive capability
                        its long-term ligti@ requirements are as high or            would be a powerful tool for resource managers
                        perhaps even higher than those of Halodule                  to use in water management programs designed
                        wrightii and S. filiforime (Vincente and Rivera             for the protection and restoration of seagrasses
                        1982. Phillips and Lewis 1983, Iverson and                  (Kenworthy and Hauncrt 1991, Zimmerman et al.
                        Bittaker 1986, Kenworthy and Haunen 1991).                  199 1, Morris and Tomasko 1993). The adequacy
                        Reported patterns of depth distribution almost              of this prediction will depend (in the assumptions
                        always indicate that Halodule wrighrii and S.               that an average annual attenuation coefficient or
                        fififoryne grow deeper than T testudinum,                   some other relevant variable is a reliable
                        reinforcing the hypothesis that factors other than          predictor of seagrass condition and that the
                        carbon balance alone are important in                       factors responsible for light attenuation can he
                        determining light requirements and depth                    isolated for management attention. Currently.
                        distribution (Zimmerman et al. 195@t).                      these are two areas of active research interest and
                                                                                    should draw the attention of scientists and
                        The larger reservoir of belowground tissues in T            managers during development of the US,
                        testudinum meadows may be vulnerable to the                 Environmental Protection Agency's Coastal
                        phytotoxic effects of reduced sulfur compounds              Submerged Aquatic Vegetation Initiative (see,
                        al the lower light levels in relativelydeeper               for example, Morris, and Toniasko 1993).
                        water, or during temporary and seasonal periods
                        of poor water transparency. The primary
                        mechanism controlling T. testudinum light
                        requirements may be phytotoxicity rather than
                        carbon balance. whereas Halodule wrighiii is
                        better adapted to minimize both problems.
                        Halodule wrightii can avoid phytotoxicity and
                        maximize carbon balance by having greater
                        oxygen production at low light levels (high
                        alpha). a higher maximum photosynthetic rate
                        (high P., Williams and McRoy 1982.
                        Fourqurean 199 1. Kenworthy 1992), a shallower
                        rooting depth, and lower root-rhizome to shoot
                        ratios (Fourqurean and Zieman 199 1. Fourqurean



                        Seajerass Monitoring and Research - 1992                                                            Paze 21










                            HOBE SOUND MONTHLY Kd VALUES



                       0. no -




                      -0.25-




                      -0.50


                   z
                   <  -0.75.
                   LLJ



                      -1.00



                      -i.25



                      -1.50

                              JAN   FES   MAR   APR   MAY   JUN   JUL   AUG  SEP   OCT   NOV   DEC
                                                            MONTH


                    FlgureX Seasonsi eyde ofdWbw PAR 1k*1 atteasadon (K* PAR) In a shadow dM bgooa, H&e Soa"4 he the Softhtm Indian



                                                            transparencies that are detectable along spatial
                 UNDERSTANDING AND                          and temporal gradients and directly controlled by
                    PREDICTING SEAGRASS                     three commonly monitored water quality
                                                            variables: 1) total suspended solids MS.
                    DISTRIBUTION                            frequently measured as turbidity by
                                                            nephelometric turbidity units), 2) chlorophyll
                                                            (CHL), and 3,1 dissolved organic matter (DOM.
                 Because of the wide diversity of watersheds and usually measured as color. Kirk 1988. Gallegos
                 coastal geomorphology in the Gulf of Mexico. et al. 1990. Gal le gos et al. 199 1. Moore 199 1.
                 there are a variety of nearshore ecosystems and Kenworthy and Haunert 199 1, Morris and
                 water qualities. The result is a range of water Tomasko 1993). Also important are the indirect

                 S@affass Monitoring and Research - 1992                                Pa" 22
















                         controls on water transparency operating thro           ugh        paradigm frequently assigned      to 'his  pecie., for
                         CHL and DOM. These are dissolved inorganic                         several reasons. The small, low-density. low-
                         nutrients. mainly inorganic nitrogen and                           relief canopy minimizes self-shading and allows
                         phosphorous, which stimulate phytoplankton                         more light to enter. while a shallow rooting
                         and macroalgal blooms as well as the growth of                     depth avoids the pi)tenfially phytotoxic effects in
                         epiphytes on the leaves of seagrasses. Both the                    the deeper, more reduced sed i men ts.
                         direct and indirect controls of light attenuation                  Additionally. Halophila dtcipiens has a
                         have very strong seasonal signatures (Moore                        simplified anatomy including thin cell walls and
                         199 1. Kenworthy et al. 199 1. Neckles 199 1.                      densely packed chl,)roplasts. which maximize
                         Kenworthy 1992. Morris and Tomasko 1993)                           the amount of light reaching the chlorophyll
                         which suggest that mechanisms controlling                          molecules (Josselyn ct al. 1986). The individual
                         short-term light limitation may be masked by                       leaves grow rapidly and turnover is fast enough
                         estimating the minimum light requirements of                       to minimize the establishment of epiphytes that
                         seagrasses through a simple correlation between                    could further attenuate light on the surfaces of
                         an average annual light attenuatior coefficient                    the leaves (Josselyn et al. 1986, Kenworthy et al.
                         and the maximum depth of growth (Dennison                          1989). Based on these physiological and
                         1987, Duarte 1991, Kenworthy and Haunert                           morphological attributes, Halophila decipiens
                         199 1. Zimmerman et al. 199 1).                                    should have a lower minimum light requirement
                                                                                            than the larger species (Josselyn et al. 1986). yet
                         The problem with inferring light limitation by a                   they grow only in summer during maximum
                         correlation between maxinturn depth of growth                      photoperiod and intensity.
                         and ft average annual attenuation coefficient
                         was illustrated by an intensive study of the                       There is another plausible explanation for the
                         submarine light regime and seagrass distribution                   observed seagrass depth distribution that is
                         in the southern Indian River (Kenworthy et al.                     based on the life history of these species rather
                         199 1, Kenworthy 1992). Weekly sampling of                         than just their physiological anI anatomical
                         the light attenuation coefficients in two coastal                  characteristics. Althoughsexual reproduction
                         lagoons showed significant effects related to                      occurs with all the species growing in the Gulf of
                         time and distance from an inlet. During four                       Mexico (McMillan 1985, Moffler and Durako
                         years of sampling, a repeatable cycle of summer                    11987). Halophila decipiens is by far the most
                         maximum and winter minimum transparencies                          fecund. In the southern Indian River
                         was detected (Fig. 3). Based on the average                        (Kenworthy 1992). and even in the tropical
                         annual light attenuation coefficient, Halodute                     environment of the Salt River Canyon in St.
                         wrightii and S. filiforme grew to a maximum                        Croix (Josselyn et al. 1986. Williams 1988.
                         depth corresponding to light levels of 15 and                      Kenworthy et al. 1989). ephemeral populations
                         37% of the incident light. Even though light                       of Halophila decipiens are reestablished
                         levels exceeded this average value in deeper                       annually by seed. During the winter periods of
                         water during the summer months (May-August).                       low light and low temperatures in the Indian
                         these two species could not establish permanent                    River, populations of Halophila decipiens
                         populations there. Yet. healthy populations of a                   disappear except in the immediate vicinity of
                         smaller species, Halophila decipiens. grew in the                  inlets, where relatively warmer and clearer water
                         deeper water between May and October                               prevails throughout the winter. In other
                         (Kenworthy 1992). If observations on seagrass                      subtropical and tropical locations fall and -winter
                         distribution were obtained only during the clear                   storms contribute to the erosion and burial of
                         suriuner period the depth transects would have                     existing Halophila decipiens beds. leading to a
                         suggested that Halophila decipiens was the                         seasonal decline in abundance and cover; this
                         species adapted to the lowest light levels, a                      occurs even in tropical deepwater beds of the

                         SeagMs Monitoring and Research - 1992                                                                         Paw 23














                              Virgin Islands (Williams 1988).     In the Big Bend           physiology. anatomy, or temporally static depth
                              region of the eastern Gulf of Mexico there are                transecLs alone. Seagrass light requirements
                              vast areas of deep water (depth > 10 m) on the                depend in part or. the life history patterns of the
                              continental shelf that are vegetated by Halophila             individual species, reinforcing the argument Lhat
                              decipiens and Halophila engelnianni    .                      an average annual attenuation coefficient may
                              (Continental Shelf Associates Inc. and Martel                 not adequately predict the distribution of some
                              Laboratories Inc. 1985, Confintal Shelf                       seagrasses (Zimmerman et al. 1991). The
                              Associates Inc. 1989). Although there are no                  survival. growth. and year-to-year persistence (if
                              detailed seasonal studies of these deepwater                  Halophila deripiens in die lidian River
                              beds. an evaluation of Hurricane Elena's impact               ce i.,imunities may depend largely on the water
                              in 1985 revealed that Halophila meadows were                  quality in summer, when actively growing
                              completely destroyed, yet they recovered during               population 's are forming seed stocks that will be
                              the following growing season (Continental Shelf               the basis for the next year's population. If
                              Aisociates Inc. 1987). This indicates that these              growth and fruiting slow or cease during cooler
                              populations are based on an annual life history               months (October-Aprfl). the light attenuation
                              strategy.                                                     values obtained in winw will have no bearing at
                                                                                            all on predicting the success of populations in
                              The storm-impacted beds in the Gulf of Mexico                 subsequent years.
                              and St. Croix, and the seasonally ephemeral
                              Halophila decipiens beds of the southern Indian               This same argument probably applies to the three
                              River, are reestablished by seed. In the Indian               larger species as well, but for different reasons.
                              River seedlings emerge in early spring (March-                During the active growing periods of spring.
                              May) and continue to germinate throughout the                 summer. and early fall. good water transparency
                              summer, forming patchily disuibuted meadows                   may ensure an adequate production of '
                              in deeper water but never in the canopy of the                belowground storage carbohydrates that can be
                              larger specieg that grow in relatively shallower              mobiliLed to short shoots during periods of algal
                              water. Seed germination, seedling growth. and                 overgrowth or low light in winter, or for
                              bed development coincide with ihe highest levels              regrowth the following spring (Dawes 1987,
                              of PAR observed during the year (Kenworthy                    Tomasko and Dawes 1989). Equally or perhaps
                              1992). Because Halodule wrightii. S. filifomie.               more important. for the larger species that
                              and T. testudinum reproduce mainly by                         produce considerable belowground biomass. is
                              vegetative branching (Tomlinson 1974). they                   the immediate production of oxygen and carbon
                              have limited dispersal potential. These larger                skeletons. These end products of photosynthesis
                              species cannot utilize the available light in                 detoxify reduced sulfur compounds and nitrogen
                              deeper water because the time window is too                   (nitrate), whereas the production of alternate end
                              short.for vegetative propagation and dispersal to             products (carbon compounds) minimizes the
                              take advantage of the resource. Volunteer                     phytotoxic effects of ethanol during nighttime
                              fragments, consisting of a few short shoots.                  and during daytime periods of low light
                              rhizomes. and roots of these three larger species,            (Pregnall et al. 1984. Smith et al. 1988).
                              recruit to the deeper areas in summer but they do             Because the ftee larger species are perennial.
                              not survive the reduced light periods of winter               growing and metabolizing all year. winter ligbi
                              (Kenworthy 1992).                                             attenuation will have a greater effect on them
                                                                                            than it would on a species like Halophila
                              These observations indicate that the depth                    decipiens, which overwinters in a seed bank. An
                              zonation patterns and the inferred minimum light              average annual light attenuation coefficient may
                              requirements of seagrasses in the Gulf of Mexico              be a better predictor of depth distribution for the
                              are more complex than can be described by                     larger species in the more southerly latitudes of

                              Sea-gragg itfonitoring and Research - 1992                                                            Page 21















                            the Gulf of Mexico. however, we should                          SEAGRASS CONSERVATION AND
                            continue to examine the concept of a critical time                  RESTORATION
                            period in order to develop a more sensitive
                            predictor for each of the species, regardless of
                            size (Moore 199 1). For example. in more                        Our efforts to protect and maintain the diversity
                            northerly regions of the gulf the annual growth                 and product-ivity of seagrass communities in the
                            period of Halodule wrightii may be shortened by                 Gulf of Mexico will dep-end tin our ability it)
                                                                                            St'
                            low winter temperatures, this argues for a                        stain good water quality. In order to do this
                                                                                            we must develop comprehensive water
                            smaller time window in which light attenuation
                            should impact seagrass growth.                                  management plans that include functional and
                                                                                            reliable optical water quality models that enable
                            Even within the genus Halophila the two species                 resource managers to identify the parameters
                            appear to have different requirements for growth                having the greatest influence (in transparency
                            (Dawes et al. 1986, Dawes et al. 1989).                         (Ki,-k 1999, Gallegos et al. 1990. 6allegos et al.
                            Halophila decipiens will grow right up to the                   199 1, Kenworthy 1992, Morris and Tomasko
                            edge of a meadow but is rarely found growing                    1993). Within a comprehensive plan, regional
                            within the canopy of the larger species.                        and local resource agencies would establish
                            Halophila engelmanni grows in the understory                    desirable goals for seagrass species and coverage
                            of the larger species or in mixed beds with                     based on existirg and/or historical seagrass
                            Halophila decipiens (McMillan 1985,                             distribution and abundance data. These goals
                            Continental Shelf Associates Inc. and Martel                    would be matched with the species pool. curTent
                            Laboratories Inc. 1985, Onuf 1991, Kenworthy,                   water quality conditions, and the hathyrnetry of
                            personal observations in the Banana River.                      the watershed. lagoon, or estuary in order to
                            Florida). Both species are often the deepest                    e,,aluate the goals with respect to the cost of
                            dwelling but Halophila engelmanni behaves                       achieving such goals. An essential feature to this
                            more like a perennial than an annual plant.                     plan Is a scientifically based water quality
                                                                                            monitoring prograin that identifies a functional
                            Based on the above discussion, w     Iater quality,             variable (e.g., the attenuation coefficient) for
                            particularly water transparency, is expected to                 predicting seagrass species and their distribution.
                            have a major influence on determining the                       In addition. the monitoring program must be
                            species composition and abundance of                            capable of identifying the water quality factors
                            seagrasses in the Gulf of Mexico. The five                      that control the functional variable (e.g.. DOM.
                            seagrass species. with their diverse anatomy,                   TSS. C14L. and dissolved inorganic nitrogen).
                            varying structural complexity, and widely                       When properly calibrated. optical water quality
                            ranging habitat requirements. provide different                 models can be used to quantitatively compare the
                            functions and values for the flora and fauna of                 relative contributions of the individual factors.
                            the gulf. Presumably, seagrasses can act as a                   For example, a dependent variable such as the
                            mediary in transmitting the detrimental effects of              light attenuation coefficient or the percent (if
                                                                                            surface iff adiance can he evaluated as   9  function
                            degraded water quality to secondary production                  of one or several independent variables on-a
                            and the health and well-being of fish and wildlife              contour plot to estimate their relative
                            (Kenworthy and Haunert 199 1).
                                                                                            contributions to PAR attenuation (McPhet son
                                                                                            and Miller 1987. Vant 1990, Gallegos et al.
                                                                                            1991, Deronsion et al. 1993, Gallegos and
                                                                                            Kenworthy 1993, Gallegos In Press). This type
                                                                                            of comprehensive. analysis provides a means for
                                                                                            deterridning the target parameter for


                            Seajerass Monilorin2 and Research - 1992                                                                  Pa-ve 25
















                           management efforts needed to improve water
                           transparency. 1rhis approach avoids the
                           inadequacies of traditional water quality criteria
                           and standards where single numeriLal values or
                           vague narratives are assigned as targets for
                           which water quality parameter values cannot be
                           exceeded. Given the diverFay of environments
                           and seagr&qs habitat requiT--ments known to exist
                           in the Gulf of Mexico, a n ore flexible approach
                           is needed. Any effort to ii ripose the same
                           standard for water transpar !ncy in the Florida
                           Keys, the barrier island lag(,,)ns of Mississippi.
                           and the Laguna Madre will p.-obably fail because
                           the species pools and factors c(,,itrciling water
                           transparency in these coastal ecosystems are
                           likely to be very different.

                           Future efforts to conserve4nd restore the
                           valuable seagrass resources of the Gulf of
                           Mexico depend on a scientifically based
                           understanding of the light requirements of the
                           individual species and the environmental and
                           anthropogenic factors affecting the submarine
                           light regime. Research efforts should continue
                           to ft-cus on developing scientifically based water

                           measure water quality but also analyze and
                           quality monitoring programs that not only

                           interpret the parameters so that factors
                           influencing water transparency can be evaluated
                           for the protection of seagrasses,



















                           Searrass Moniforinz and Research - 1992                                                        Page 26



















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                                Continental Shelf Associates, Inc. 1989. Southwest Florida nearshore benthic habitat study. narrative
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                                Dawes, C.. C.S. Lobban. and D.A. Tomasko. 1989. A comparison of the physiological ecology of the
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                                                                                             J
              			  Dennison. W.C. 1087.   Effects of light on seagrass photosyn&.esis. growth and depth distribution.
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                                Dennison. W.C. 1991. Photosynthetic and growth responses of tropical and temperate seagrasses in
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                                Dennison. W.C. and R.A. Alberte. 1986. Photoadaptation and growth of Zostera marina L. (eelgrass)
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                                 Sea12qvass Afoniforiniz and Research - 1992                                                         Page 28
















                         Kenworthy, W. J. 1992. Protecting fish and wildlife habitat through an understanding of the minimum
                            light requirements of subtropical -tropical seagrasses of the southeastern United States and Caribbean
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                            Progress Series 51:277-290.

                         Kenworthy. W.J., M.S. Fonseca. and S,.D. DiPiero. 199 1. Defining the ecological light compensation
                            point for seagrasses Halodule vs-righiii and SYringodiumfiliforme from long-terrn submarine light
                            regime monitoring in the southern Indian River. Pages 106-113. in W.I. Kenworthy and D.E'. Haunen
                            (eds). The light requirements of seagrasses: proceedings of a workshop to examine the capability tit'
                            water quality criteria. standards and monitoring programs to protect seagrasses. NOAA Technical
                            Memorandum NMFS-SEFC-287.


                         Kenworthy, W.J. and D.E. Haunert. 199 1. The light requirements of seagrasses: proceedings of a
                            workshop to examine the capability of water quality criteria. standards and monitoring programs to
                            protect seagrasses. NOAA Technical Memorandum NMYS-SEFC-287. 181 pp.

                         Kirk. J.T.O. 1988. Optical water quality-what does it mean and how should we measure it? Journal of the
                            Water Pollution Control Federation 60:194-198.


                         Marsh..I.A. Jr.. W.C. Dennison. and R.S. Alberte. 1986. Effects of temperature on photosynthesis and
                            respiration in eelgrass (Zostera marina L.). Journal of Experimental Marine Bio!ogy and Ecology 10):
                            257-267.


                         McMillan. C. 1985. The seed reserve for Halodule wrighrii, S'vringodiumfilifonne and Ruppia maririnia
                            in Laguna Madre. Texas. Contributions in Marine Science 28:141-149.

                         McPherson, B.F. and R.L. Miller. 1987. The vertica! attenuation of light in Charlotte Harbor. a shallow,
                            subtropical estuary in southwestern Florida. Estuarine Coastal and Shelf Science 25:721-737.

                         Moffler. M.D. and M.J. Durako.' 1987. Reproductive biology of the tropical -subtropical seagrasses of the
                            southeastern United States. Florida Marine Research Publications 42:77-88.


                         Moore, K.A. 1991. Field studies of the effects of variable water quality on temperate seagrass growth and
                            survival. Pages 42-58 in W.I. Kenworthy and D.E. Haunerl (eds), The light requirements ollscagrasses:
                            proceedings of a workshop to examine the capability of water quality criteria. standards and monitoring
                            programs to protect seagrasses. NOAA Technical Memorandum NMFS-SEFC-287.

                         Morris, L.J. and D.A. Tomasko, (eds). 1993. Proceedings and conclus:o!n,317 workshops on: subincrged
                            aquatic vegetation and photosynthetically active radiation. Special Polication SJ93-SP 13. Vilatka.
                            Fla.: St. Ichns River Water Management District. 244 pp.+ Appendices.

                         Neckles. H.A. 1991. Complex interactions among light-reducing variables in seagrass systems:
                            simulation model predictions for long-term community stability. Pages 127-132. in W.J. Kenworthy,
                            and D.E. Haunert (eds), The light requirements of seagrasses: proceedings of a workshop to examine


                         Seaerass Monitorinje and Research - 1992                                                   Page 29















                                  the capability of water quality criteria, standards and monitoring programs to protect seagrasses.
                                  NOAA Technical Memorandum NMF-S-SEFC-287.

                              Onuf. C.P. 199 1. Light requirements of Halodule vs-rightfi. S 'vringodiuntfiliforme.md Halophila
                                  engelmanni in a heterogeneous anj variable environment inferred from long-term monitoring. Pages
                                  95-105 in W.I. Kenworthy and D.F. Haunerl (eds). The light requirements of seagrasses: proceedings
                                  of a workshop to examine the capability of water quality criteria. standards and monitoting programs (o
                                  protect seagrasses. NOAA Technical Memorandum NMFS-SF.FC-287.

                              Penhale,. P.A. and R.G. Wetzel, 1983. Structural and functional adaptations (if ecigrass (Zostera marina
                                  L.) to the anaerobic sediment environment. Canadian Journal (if Botany 61:1421-1428.

                              Phillips. R.C. and R. R. Lewis. 1983. Influence of environmental gradients on variations in leaf widths
                                  and transplant success in North American scagrasses. Marine Technology Society Journal 17:59-68.

                              Pregnall, A.M.. R.D. Smith. T.A. Kursar, and R.S. Alberte. 1984. Metabolic adaptation of Zostera marina
                                  (eelgrass) to diurnal periods of root anoxia. Marine Biology 83:141-147.

                              Smith, R.D.. W.C. Dennison. and R.S. Alberte. 1984. Role of seagrass photosynthesis in root aerobic
                                  processes. Plant Physiology 74:1055-1058.

                              Smith. R.D.'A.M. Pregnall, and R.S. Alberte.    1998. Effects of anacrobiosis on root metabolism of the
                                  seagrass'
                                          Zostera marina L. (eelgrass). Marine Biology 98:131-14 1.

                              Tomasku. D.A. and C.J. Dawes. 1989. Evidence for physiological integration between shaded wid
                                  unshaded short shoots of Thalassia testudinum. Marine Ecology Progress Series 54499-305.

                              Tomlinson, P.B. 1974. Vegetative morphology and meristem dependence-the functional aspects of
                                  productivity in scagrasses. Aquaculture 4:107-130.

                              Vant. W.N. 1990. Causes of light attenuation in nine New Zealand estuaries. Estuarine Coastal Shelf
                                  Science 31:125-138.


                              Vincente. V.P. and J.A. Rivera. 1982. Depth limits of the seagrass Thalassia testudinum (Konig) in Jobos
                                  and Guayaailla Bays, Puerto Rico. Caribbean Journal of Science 17:73-77

                              Williams. S.L. 1989. Disturbance and recovery of a deep-water Caribbean seagrass bed. Marine Ecology
                                  Progress Series 42:63 -7 1.

                              Williams. S.L. and C.P. McRoy.    1982. Seagrass productivity: the effect of light on carbon uptake.
                                  Aquatic Botany 12:321-344.

                              Zieman, J.C., J.W. Fourqurean, and R.L. Iverson. 1989. Distribution. abundance and productivity of
                                  seagrasses and macroalgac in Rorida Bay. Bulletin of Marine Science 44:292-311.





                              Sewass Monitorini and Research - 1992                                                            Page 30











                         Zieman, J.C. and R.G. Wetzel. 1980. Producdvity in seagrasses: methods and rates. Pages 87-116 in
                            R.C. Phillips and C.P. McRoy (eds), Handbook of seagrass biology: an ecosystem perspective. Garland
                            STPM Press, New York.

                         Zieman, J.C. and R.T. Zieman. 1989.  The ecology of the seagrass meadows of the west coast of Florida:
                            A community profile. United States Fish and Wildlife Service Biological Services Report 85(7.25).
                            155 pp.

                         Zimmerman. R.C., J.L. Reguzzoni, S. Wyllie-Echeverria, INC Josselyn. and R.S. Alberte. 1991.
                            Assessment of environmental suitability for growth of Zostera marina 1 (eelgrass) in San Francisco
                            Bay. Aquatic Botany 39: 353-366.

                         Zimmerman. R.C., R.D. Smith, and R.S. Alberte. 1989. Thermal acclimation and whole-plant carbon
                            balance in Zostera marina L. (eelgrass). Journal of Experimental Marine Biology and Lcology 130:93-
                            109.









































                                 Seagrass Monitering and Research - 1992                                                   Page 31
 



















                         SUBMERGED AQUATIC VEGFTATION MAPPING

                                         WORKING GROUP REPORT


                                                              by


                                                     Lawrence R. Handley

                                                   National Biological Survey
                                                   Southern Science Center
                                                     700 Cajundome Blvd.
                                                     Lafayette, LA 70506

















                   -Seagrass Monitoring and Research - 1992                                      Page 33
















                                primary goal of this working group was to                  Gulf of Mexico from aerial photography
                           review, discuss, and recommend criteria for                     acquired in 1983. and their wetland and upland
                           mapping the location and extent nf submerged                    maps developed for each (if the coastal states
                           aquatic vegetation (SAV) in the coastal region of               include SAV. Inconsistent identification (if SAV
                           the Gulf of Mexico as an indicator of nearshore                 limits the utility of these. historical weetland and
                           environmental quality. The area under                           upland maps. Seagrass trend maps at a scale of
                           consideration for this discussion is the                        1: 100,000 have been developed for the Laguna
                           Louisianan Province of Environmental                            Madre of Texas using 1989 field mapping and
                           Monitoring and Assessment Program -Estuaries,                   master's theses for two dates. Seagrass maps
                           which includes the coastline of the Gulf of                     have been developed for trends analysis for the
                           Mexico from Brownsville, Texas. to Anclote                      Chandcleur Islands of Louisiana for nine time
                           Key, Florida. This includes the coastlines of the               periods, for Perdido Bay, Horida-Alahama, for
                           states of Texas, Louisiana, Mississippi. and                    four dme periods. and for the NPS Gulf Islands
                           Alabama. and the northwestern coast of Horida.                  Nabonal Seashore, Mississippi -Alabania-Flofida.
                           The area of concern includes bays, sounds. and                  for three time periods. Seagrass mapping for
                           estitaries from their offshore limi! to the inland              four fime periods for St. Andrew's Bay, Florida.
                           lind of asLronomical tidal influence.                           is in progress.

                                                                                           Although NOAA has developed a major seagrass
                           EXISTING MAPPING PROjECTS                                       mapping program for the North Carolina coast.
                                                                                           they have not mapped any areas in the Gulf of
                                                                                           Mexico. They have been the principal instigator
                           What maps, data, or information are available
                           and planned by Federal and State agencies                       and coordinator in the development of a seagrass
                           wPhin the Gulf of Mexico area? What is the                      mupping protocol. The Minerals Management
                           areal coverage of the projects? What kind of                    Service funded the development of seagrass
                           cooperation exists among agencies for each                      atlases for the Florida Big Bend area in 1985 and
                           project? EMAP-Estuaries has begun a mapping                     the Florida Day area in 1985-1987. These atlases
                           project of SAV within the Louisianan Province.                  are being done at a scale of 1: 100.000.
                           This project will acquire 1:24,000 scale natural                The NPS has funded the U.S. Fish and Wildlife
                           color aerial photography of the Gulf Coast over                 Service (USFWS) to map the Gulf Islands
                           four years. The photography will be interpreted,                Nati.onal Seashore for three time periods and is
                           mapped as overlays to U.S. Geological Survey                    currently developing a contract for field
                           (USGS) 1:24,000 scale quadrangles, and                          inventory of seagrasses present. If funding is
                           digitized to provide SAV acreages. The National                 available they will fund the USFWS to develop
                           Biological Survey's (NBS) Southern Science                      seagrass maps for tht; Gulf Islands for the early
                           Center is the project leader and is responsible for             1940's.
                           completing the photointerpretation and mapping.
                           Other project participants include the National                 The states around the Gulf of Mexico coast have
                           Oceanic and Atmospheric Administration                          varied in program development related to
                           (NOAA) for seagrass mapping protocols, and the                  seagrass inventory and mapping. Texas and
                           National Park Service (NPS) and the states of                   Florida have active mapping programs. and
                           Florida. Alabama, Mississippi, Louisiana. and                   Alabama mapped the seagrasses of MobJe and
                           Texas for review and ground-truthing.                           Perdido bays in the late 1970's. but Louisiana
                           The NBS is responsible for most of the seagrass                 and Mississippi have never inventoried or
                           mapping in the Louisianan Province completed                    mapped their SAV (although the Louisiana
                           to date. They prepared seagrass adases for the
                                                                                           Department of Natural Resources Coastal


                           Seagrass Monitoring and Research               1992                                                       Page 34















                            Management Division was very active in the                    0  Matches other programs (e.g., National
                            rcview and ground-truthing of the aquatic beds                   Wetlands Inventory).
                            in the 1988 USFWS wetlands habitat maps for
                            coastal Louisiana).                                           0  App;ieable to county- and parish-level
                                                                                             planning.
                            The University of Texas Bureau of Economic
                            Geology has mapped the entire coast of Texas                  0  Used for screening permits and regulatory
                            for SAV for the late 1950's and for 1979-1980.                   monitoring.
                            Ile Texas Department of Parks and Wildlife has
                            inventoried and mapped Galveston Bay, San                     0  Widely available.
                            Antonio Day, and Nueces Bay. They also have
                            an ongoing project for Corpus Christi Bay.                    0  Allow visualization in the field.

                            The Florida Department of Natural Resources                   0  USGS has an active updating program.
                            has completed trends analysis for St. Andrews
                            Day   and has ongoing projects to redo the 1983               DISADVANTAGES:
                            USFWS seagrass photographic atlases an      d to
                            establish trends for Tampa Bay.                               0  Too coarse for small impacts (e.g.. prop scars.
                                                                                             boat docks).

                            BASE MAPS                                                     0  Minimum of 114 acre mapping.

                            Do we have adequate base maps? Base maps are                  0  For some quadrangles only orthopho(os have
                            a common map depiction of the coastline in a ;                 I been produced.
                            common coordinate system at some level of map
                                                                                          0  Digital data for quadrangles lacking for many
                            accuracy standards. such as USGS 1:24.000                        areas.
                            topographic quadrangles or 1:40,000 National
                            Ocean Survey (NOS) nautical charts. It will be                0  Lack or submerged information (e.g..
                            difficult to complete historical mapping or to                   bathymetry).
                            match mapping projects from one state or region
                            to another without the application of a common                0  Many maps are outdated for changing
                            base map series.
                                                                                             coastlines.
                            The 1:24,000 USGS topographic quadrangles are                 There are alternatives to the USGS topographic
                            the most available and widely used base maps                  quadrangles as base maps. The NOS -shoreline
                            and should be considered the minimum base                     manuscript maps are at scales of 1:20.000 or
                            map, in terms of formal and scale, to be used for             1: 10,000. However, they are limited in their
                            scagrass mapping.                                             availability, they are not available in a digital
                            There are advantages and disadvantages to                     form, and other coastal features (e.g.. marsh.
                            working with the USGS 1:24,000 maps:                          cultural features, and roads) are lacVing. Other
                                                                                          projects are dcveloring their own base maps
                            ADVANTAGES:                                                   because the scope of the projects demands maps
                                                                                          at scales of 1:20,000, 1:12,000. or 1:6.000.
                            0 USGS is the national standard.                              Other mapping efforts may use 1: 100,000 scale
                                                                                          USGS base maps that cover large offshore areas


                            Seagras@ Monitoring and Research - 1992                                                               Page 35







 iz


                         and/or areas where detailed data are not available             during photo interpretation and even slight
                         nor deemed necessary.                                          amounts of turbidity destroy the signature.

                                                                                        Signature Identification: Tile photointerpreter
                         GROUND DATA TO COLLECT IN                                      (PI) gains confidence with repeated signature
                            THE MAPPING EFFORT                                          identification. That identification includes
                                                                                        pholointerpretation and the collection (if data in
                         What she-specific data should be collected in the              the field. Although study has shown
                                                                                        interpretation can he done without PI field
                         field as indicators for photointerpretation?                   participation, it is generally recommended that
                         Ground-truthing for SAV mapping should            Ibe          the PI be involved in the field effort. The PI has
                         done by the photointerpreter. The ground-                      to know how the signatures correspond to SAV
                                                                                        in the water. In addition. a PI lacking field
                         truthing focuses on the identification of the SAV              experience may no( know all the pertinent
                         photo signature. Point-specific locations of                   information to ask the field worker. thus
                         1. questionable interpretation" are primary field              affecting the accuracy of the final product.
                         check sites, and other areas of "confidently
                         interpreted" SAV are covered by a grid system.                 Nonvegmted Feature : When at a site, the field
                         transects, or random point field check sites.                  person should be aware of objeas that could he
                         There is a difference between ground data to be                confused   with SAV on the aerial photographs
                         acquired as aids to photointerpretation and that               (e.g., eroding peat banks, geologic formations.
                         used as verification of the mapping completed.                 etc.).
                         EMAP requires that if a monitoring location is
                         placed in an area where seagrasses are mapped                  I ocation: The correlation of afield collection
                         on the 1:24,000 quadrangles. seagrasses'must be                site, transect. or plot with a location on the aerial
                         present. Therefore. mapped seagrass beds must                  photographs is essential to photointerprelation
                         be verified as present or absent through field                 and verification of signatures. This is even more
                         review. The key elements in tying ground data                  important when looking at vegetation density
                         to the pholointerpretation are species present,                and species composition.
                         signature identification conflirmation, .
                         nonvegetated features, and location. Other field               Density: Estimating density requires extensive
                         data that may be collected as part of the mapping              field sampling and is potentially a major
                         effort but are not critical as aids to the                     resource expenditure that can limit the number of
                         photeinterpreter in SAV delineation include                    sampling stations. There are two types of
                         vegetation density, water depth. presence or                   density that can be estimated: 1) the ground
                         abundance. of epiphytes, evidence of prop scars,               cover approach estimates the density of SAV
                         sediment type, light attenuation, salinity, and                within a patch or bed. i.e. the percent of surface
                         presence or abundance of macroa:gae.                           covered by blades and stems, and 2) the patch
                                                                                        density approach estimates the density of patches
                         Sp"ies Present: In most instances, species                     of SAV across the area. i.e.. the number. size.
                         cannot be distinguished in a photo (although                   and distribution of patches compared to the
                         there are a few exceptions). Although aerial                   amount of bare ground across the surface. The
                         photographic signatures for Halophila sp. have                 ground cover approach is certainly the most
                         been identified through fieldwork in water                     desired, but it requires considerable control in
                         depths greater than 15 m, aerial photography is                terms of scale. emulsion. water clarity. water
                         no, practical for mapping in deep water because                depth, and field work. Accurate estimation of
                         the water often obscures detection of grass beds               ground cover through pholointerpretation is not

                         Seagrass Monitoring and Research - 1992                                                                  Page 36














                        always achievable because water clarity and                       samples may include redox readings. dry weight
                        depth can lighten submerged vegetation, making                    organic content, statistics on sediment grain size.
                        it appear less dense. Also the relation between                   or the percent sand. silt. and clay. Although data
                        photographic signature and density can vary                       on sediment types are important in the
                        between species and even within a species                         comparison of sediment type and organic content
                        depending on blade lengLii, width, pigmentation.                  to submerged vegetation density and species
                        degree of epiphytization and aspect (lying over                   comrx)sition. the sediment type data have little
                        versus standing upright). To achieve an estimate                  application in the pholointerpretation pr(wess.
                        of ground cover with a stated degree of accuracy
                        requires considerable fieldwork. As a result, it is               I i&ht Attenuation: Turbidity plumes in the
                        time-consuming and expensive. Estimating                          water column caused by suspended sediment or
                        patch density is more economical and feasible                     algae can obscure the signature of SAV. Data on
                        through photointerpretation. thus providing                       light attenuation can he gathered by use of light
                        accurate descriptions of SAV distribution.                        meters lowered within the water column. Such
                                                                                          data are important in understanding the growth,
                        Water Dep : Although not essential in the                         structure. and composition ofSAV. Turbidity is
                        photointerpretation process, data on water depths                 easily i'dentified in aerial photographs. but,
                        (soundings. pole measurements. bathymetric                        attenuation data are not essential in the
                        maps. etc.) can aid the PI by identifying the areas               identification of SAV signatures.
                        within the optimal range for SAV growth, or by
                        ident"fyLng dark signatures in the water as                       Sidinity: Although salinity can cause
                        resulting from deep water rather than from SAV.                   considerable variation in SAV species
                        Water depth at the time the aerial photography is                 composition. density, and growth. salinity data
                        acquired can affect the signature of the SAV                      are not necessary in the identification of SAV
                        present. The vegetation will apptar darker if the                 signatures.
                        water level is low and the blades are lying over
                        than if the water level is high and the blades are                Mamalga         Macmalgae take' two forms: drift
                        more upright.                                                     algae moving with bottom currents. and attached
                                                                                          macroalgae. generally found in shallow low-
                        Epiphytes: The amount and type of epiphytes                       energy water. Although m&Toalgae are
                        present are important field data to be collected to               generally found in shallow water they may
                        determine the health and condition of SAV, but                    appear darker than other SAV and often have
                        they are very seasonal in occurrence and it is not                circular patterns within the signature. More
                        possible to photointerpret them. In addition.                     often the signature of macroalgae is
                        sampling epiphytes is extremely time consuming                    indistinguishable from that of other forms of
                        and would therefore require a large commiltment                   SAV. and field determinations are necessary.
                        of resources.


                        5=: Prop scars are easily identified on low-
                        level (e.g.. 1:6,000 scale) aerial photography.
                        They may be mapped and their revegetation
                        followed for subsequent time periods. They help
                        in establishing locations on the aerial
                        photography.

                        Sediment L= Sinficial sediments are easily
                        collected at field sites. Data derived from


                        Seagrass'Monitoring and Research - 1992                                                                       Pagi 37'
















                            NEW TECHNOLOGY IN                                                 0 GPS can reduce the amount of time needed to
                               SEAGRASS MAPPING                                               physically locate the bcds appearing in aerial
                                                                                              photographs during post-flight ground surveys,
                            The most impcrtant questions surrounding new                      0 To allow for statistical accuracy. more pre-
                            technology associated with image acquisition                      flight field time is required for putting out
                            are:                                                              targets that can be seen on the photo (unless
                                                                                              permanent visible features are already present).
                               What remotely sensed imagery exists that we
                            could successfully use?                                           9 GPS provides horizontal control of aerial
                            0 Ist  .he remotely sensed imagery effecfive at                   photography and maps.
                            identifying SAW                                                   0 GPS solves digitization problems with
                            * Should programs be looking at these new                         rectification and geopositioning because it
                            advances in the long term?                                        incorporates GPS digital data into the pr(wess.
                            The working group expressed the opinion that                      0 GPS-ccntrolled photography costs four-to-
                            eventually SAV mapping should get away from                       five times as much as standard photography.
                            the use of aerial photos because of the increasing.               0 Certain photos require a target present in
                            costs and complexity of flight mission planning                   order to he triangulated with other photos, which
                            and coordination. The general consensus of the                    increases cost and time for cm)rdina6on.
                            working group was that, at the present time.
                            remotely sensed imagery, i.e.. satellite and                      'Me working group strongly recommended that
                            airborne scanner data. cannot provide accurate                    anyone collecting point data in SAV fieldwork
                            and consistent SAV identification. However.. the                  use GPS technology and perform differential
                            group believes that future technological                          correction on the GPS data acquired.
                            advances will bring scanner data on S,^ V within
                            the realm of consideration. Therefore we should                   fhe use of the analytical stereoplotter is another
                            stay current with all new technology even though                  ttchnological advance that can potentially he (if
                            we may not be able to use it at this time.                        importance in SAV mapping because it will
                            Use of Global Positioning System (GPS) is                         reduce the time required for mapping and the
                            considered to be the most important ,           .   .   f         cost,of mapping in the long term. The analytical
                            technological advancement in the mapping of                       stereoplotier incorporates the use of GPS field
                            SAV. Points to consider in using GPS include:                     data to rectify the aerial photography and allows
                            0 Aircraft navig    Iation technology is advan   . cing           for photo interpretation and digitization in a one-
                            rapidly and positioning using airborne GPS                        step process.
                            technology allows precise location of the plane
                            at the moment the photo was taken.                                CLASSI.FICATION

                            0 GPS provides real-time display of location
                            and coverage of the photography collected to                      The primary question formulated by the working
                            ensure acquisition of the areal coverage                          group was: What has been tradificinally
                            specified.                                                        classified when seagrasses are mappcd?

                            0 GPS technology is advancing very rapidly.


                            Seagrass Monitoring and Research - 1992                                                                      Pahe 38-













                       Most historic mapping projects have simply                   be further classified by a range of densities of
                       delineated the presence versus absence of                    patches within an area. A density classification
                       seagrasses. because of the scale of the mapping              sys(cm is presented as pan of the implementation
                       effort. the limited funding often available, a               plan for NOAA's Coastwatch -Change Analysis
                       demanding schedule. lack of fieldwork. and lack              Project (C-car@ I)ohson et al. 1994).
                       of PI expertise in recognizing seagrass
                       signatures. Also, the simple presence versus                 The I.,ouisianan Province SAV mapping
                       absence of seagrasses allows easier replication of           classification for EMAP includes a gradient of
                       effort to determine trends of seagrass change.               SAV patch densities (from continuous coverage
                       Macroalgal presence is also identified as a                  through four density classes), and the presence
                       separate category in some projects.                          of macroalgae beds.

                       The working group agreed that it is better to
                       have fewer classifications. The simpler the                  STRATIFICATION OF SAMPLING
                       classification. the fewer "gray" areas for
                       interpretation. The interpretation of seagrass               Once the baseline mapping for SAV present in
                       density has been attempted in several projects in            the Louisianan Province is completed. EMAP
                       the past, are each with inconsistent results.                intends to develop a monitoring program to
                       Generally, theintent in seagrass mapping is to               assess status and trends of these habitats.
                       describe the morphology of the be   d as a whole.            Because SAV beds vary widely in size. shape.
                       not the density of seagrasses within the bed. In a           and ecological charvteristics. some form of a
                       USFWS study. prefiminary data indicated the                  priori stratification is necessary to ensure
                       accuracy of interpretation of seagrass densities             adequate and representative sampling.
                       over 70% and under 30% was nearly 70%,
                       whereas interpretation of the moderate of                    Sampling may be stratified by several criteiia:
                       w4ium density range (30-70%) was
                       approximately 50%. The classification of                     0 Geographic location (distance from shore,
                       seagrasses by species, or the separation of                     estuaries, river mouths. islands. behind
                       freshwater species from seagrasses, has also been               barriers. open Gulf).
                       attempted, but it cannot be consistently
                       interpreted from aerial photography and requires             0  Salinity (may not be repeatable from year to
                       extensive fieldwork and ground-truthing.                        year as salinity can change radically).
                       Interpretation of species composition and density
                       is affected by the lack of homogeneity (although             0  Substrate type.
                       turtlegrass may be interpreted with some
                       consistency as a darker signature, other seagrass            e  Anthropogenic stresses (dredging. boating
                       speci,.s are not as easily discerned and the                    access,, contamin&its).
                       "species composition of mixed beds is impossible
                       to determine from serial photography) and                       System size.
                       changing water depths (as water depth increases
                       the water signature gets darker).                            0  Areal extent of SAV beds.
                       Morphologic classification can be accomplished               0  Water depth.
                       from aerial photography. Past projects have
                       identified "continuous" beds (large areas of                 0  Relationship to physical stress (fetch).
                       seagrasses) and "patchy" beds (small scattered
                       units of seagrasses). "Patchy" seagrass beds can

                       Seagrass Monitoringr     and Research - 1992                                                         Page 39













                           0  Special management/jurisdiction..                          Polygon shape - probably not f@asihle because of
                                                                                         wide variation of shapes within each geographic
                           0  A tiered approach is suggested for the                     location to be sampled.
                              stratification of sampling.
                                                                                         Depth - ranges of depths should be sampled.

                           FIRST TIER                                                    Sediment type - sand, silt. organic mucks.

                           The first tier of sampling strata is based on
                           geographic location and system size. This will                MONITORING
                           provide adequate distribution of sampling
                           throughout all ecological systems ovailable                   The mapping working group suggested that the
                           within the Louisianan Province,.                              Y*."MAP monitoring of SAV should:
                           Lagoons - sounds or bays, protected by barrier                Tie in with existing mapping and monitoring
                           islands without large freshwater inflow.                      programs of NOAA. the NBS, state agencies. the
                                                                                         U.S. Environmental Protection Agency Gulf of
                           Estuaries - includes large and small systems (for             Mexico Program -habitat degradation committee.
                           sampling purposes include all systems on an                   and regional and county mapping programs.
                           equal basis rather than weighting systems by
                           areal extent).                                                Repeat the mapping for the Louisianan Province
                                                                                         every four years to assist monitoring. ensure
                           Big Bend Area, Florida - unique area (open                    repeatabil Iity of sampling locations-and establish
                           coastal).                                                     trends felated to 6e ecological health of the
                                                                                         province's SAV.
                           River deltas - freshwater to brackish SAV.
                                                                                         Rely on the protocols developed from the      1990
                           SECOND TIER                                                   NOAA-sponsored seagrass workshop and the C-
                                                                                         CAP program (Dobson et al. 1494).

                           The second tier of sampling strata is based on
                           seagrass bed morphology and ensures
                           representation regardless of size, coverage, water
                           depth, or sediment type. This tier is based,
                           primarily, on the ability to delineate seagrasses
                           and map them. The polygon delineates the
                           boundary of SAV beds or patches on a map.
                           Potential stratification variables include:

                           Polygon clam - continuous or patchy, density of
                           patches over area.

                           Polygon size - ranges of polygon sizes should be
                           formulated.





                           Seagrays Monitoring and Research - 1992'                                                                Page 40-

















                                                            REFERENCES


                    Dobson, J.E., E.A. Bright, R.L. Ferguson, D.M. Field, L.L. Wood, K.D. Haddad, H. Iredale III, J.R. Jensen,
                       V.V. Klemas, R.J. Orth, and J.P. Thomas, 1994. N0AA coastwatch change analysis project-guidance                     
			     for regional implementation. U.S. Department of Commerce. NOAA/Coastal Ocean
                       Prograrm/Coastwatch: Change Analysis Project. NOAA/NMFS, Beaufort Laboratory, Beaufort. NC.
                       121 pp + 19 figures.












































                                                                                                            Page 41
                   Seagrass Monitoring and Research-1992
 

























                                           ECOLOGICAL INDICATORS

                                           WORKING GROUP REPORT


                                                     by


                                             Hilary A. Neckles

                                         National Biological Survey
                                          Southern Scienct Center
                                             700 Cajundome Blvd.
                                                  
                                           Lafayette, LA 70506













                      Seagrass Monitoring and Research - 1992                                      Page 43
 














                                 The charge to this working group was to identify           RESP     ONSE INDICATORS
                                 a suite of indicators of the ecological condition
                                 of submerged aquatic vegetation (SAV) beds
                                 appropriate for long-term monitoring. Ideally,             Many plant processes can he expected to respond
                                 indicators would function on a regional scale              to changes in cnvironmental conditions.
                                 over a period of decades. Indicators must be.              Consequently. a wide range of plant
                                 applicable across a range of SAV habitat types.            characteristics should reflect environmental
                                 related to ecological condition in a way that can          change. The working group generated an
                                 be quantified and interpreted, quantifiable in a           exhaustive list of candidate response indicators
                                 standardized manner with a high degree of                  and then combined them into general categoiries
                                 repeatability. and appropriate within the                  for discussion. The categories in Table I were
                                 .constraints (financial, logistical) imposed bythe         selected from the more extensive list by
                                 spatial wd temporal scale of a regional. long-             consensus as the best indicators of habitat
                                 term monitoring program: i.e., the long-term and           condition.
                                 regional variability of an indicator must not be
                                 masked by short-term or local variability. The             None of the proposed indicators has been tested
                                 Environmental Monitoring and Assessment                    ai the regional and dccadal scales inherent in
                                 Program (EMAP) attempts to limit broad scale               EMAP sampling. Seagrass beds are dynamic.
                                 data collection for indicators of envifonmental            complex systems, and many of the parameters
                                 quality to a single index period per year. when            used to characterize habitat condition exhibit
                                 r.esponses to anthropogenic and climatic stresses          considerable temporal and spatial variability.
                                 are anticipated to De most severe (see Summers             The working group agreed overwhelmingly that
                                 et al. 199 1). The overriding concern expressed            to accurately assess seagrass, ecosystem
                                 by this working group during discussions of                condition the EMAP sampling network should
                                 candidate indicators was the potential to yield            include frequent sampling at selected permanent
                                 meaningful information if sampled only once                stations. The proposed indicators would yield
                                 during the year at sites separated by kilometers.          the most information on seagrass habitat status
                                                                                            and trends if sampled along permanent transects
                                 Working group members were asked to consider               established perpendicular to the depth gradient.
                                 parameters that could be measured to quantify
                                 integrated responses of SAV to individual or
                                 multiple stressors ("response indicators"), and            ABUNDANtE
                                 parameters that could be measured to quantify
                                 pollutant exposure or habitat degradation                  Measures of plant abundance are among the most
                                 ("exposure ipdicators"). Participants were asked           important indicators of habitat condition.
                                 also to recommend the optimal timing and                   Working group members* identi fled various
                                 methods for measurement and to suggest                     morphometric and population parameters that
                                 whether threshold values separating desirable              tend to respond to environmental change and
                                 from undesirable habitat conditions exist for              then prioritized these measures for inclusion in a
                                 candidate indicators. It became clear during               long-term monitoring program. All candidate
                                 discussions that, in many areas. further research          indicators are estimable from quadrat-based
                                 is necessary to improve our ability to                     sampling. Prioritization was based on ease of
                                 characterize SAV habitat condition over broad              measurement, predictability of response to
                                 spatial and temporal scales.                               environmental stress. and degree of temporal and
                                                                                            spatial variability (Table 1). Abundance
                                                                                            measures should be added to a monitoring


                                 Seagrqvs Monftoring and Research - 1992                                                            Page 44

















                                    program in order of priority as resources permit.                                 Shoot density: Density decreases predictably
                                                                                                                     with declining availability of light and sediment
                                                                                                                     nutrients and is less subject to variability caused
                                                                                                                     by grazing than are other measures of
                                                                                                                     abundance. Shoot density has historically been
                                                                                                                     one of the most frequently measured parameters
                                                                                                                     of seagrass populations. Thus. a long-term data
                                                                                                                     base for seagrass density under varying
                                                                                                                     environmental conditions exist- in the literature
                                                                                                                     from which thresholds of responses could
                                                                                                                     probably be generated. Because seagrass species
                                                           RESPONSE INDICATORS                                       differ in their susceptibility to environmental
                                                                                                                     stress and competitive interactions, a record of
                                        Abundance    Shoot density by species                                        densities of individual species would yield more
                                                     SAV biomass                                                     information than would a record of total
                                                     Algae biomass                                               macrophyte density. For example. among
                                                     Leaf width                                                      tropical seagrasses, Thalassia is the most
                                                     Leaf area index                                                 sensitive to certain environmental stressors and
                                        Plant consituents                                                     is the strongest competitor for nutrients. An
                                                     Soluble carbohydrate concentration                              increase in density of other seagrasses could thus
                                                     Ratio of C:N:P                                                 signal a decline in environmental condition if
                                        Species composition                                                    coupled with a decrease in eensity of Thalassia.
                                                     Seagrass
                                                     Macroalgae                                                     SAV Biomass:  Although susceptible to the
                                                     Filamentous algae
                                                                                                                     confounding effect of grazer leaf removal,
                                        Depth limit of bed                                                         biomass integrates leaf length and width and
                                        Genetic diversity                                                            therefore may be more responsive to
                                        Stress proteins                                                             environmental stress than leaf morphometry.
                                        Animals
                                        Productivity                                                              The allocation of resources between
                                                                                                                     aboveground and belowground biomass can also
                                                                                                                     yield insight into environmental stressors.
                                                           EXPOSURE INDICATORS
                                        Light                                                                        Algal Biomass: Algal growth is frequently
                                        Nutrients                                                                    correlated with nutrient enrichment. such that
                                                     Total nitrogen, total phosphorus                                high biomass of either epiphytes or unattached
                                                     Ammonuium, nitrate, soluble reactive phosphate                macroalgae may signal declining water quality.
                                        Dissolved oxygen                                                             Algal biomass is a result of interactions among
                                        Physical conditions                                                         many abiotic and biotic controls. however, and
                                                     Physical energy regimie
                                                     Sediment characterstics                                        ordinarily exhibits extreme temporal and spatial
                                                                                                                     variability. Therefore, environmental condition
                                                                                                                     cannot be interpreted definitively from algal
                                                                                                                     biomass alone. To improve the utility of algal
                                    Table 1. Ecological indicators proposed for inclusion in the EMAP                         biomass as an indicator of SAV condition.
                                    sampling network                                                                 research is particularly needed to elucidate the
                                                                                                                     complex interrelationships among light
                                                                                                                     availability, nutrient concentrations, grazing
                                                                                                                     intensity, and algal response.


                                    Seagrass Monitoring and Research - 1992                                                                                                Page 45
 















                            Leaf MoWhomcU3t: Leaf width can be used to                     environmental conditions, insufficient data exist
                            diagnose environmental changes within                          to assign critical levels for any seagrass species.
                            77ialassia populations; in general, declining leaf             Research is needed to determine thresholds of
                            widths suggest environmental stress.                           constituent concentrations indicative of
                            Information does not exist, however, to Werpret                environmental stress.
                            differences in leaf width among populations.
                            Therefore. leaf width should be considered as a                Constituent concentrations in SAV tissue will be
                            local response indicator for Thalassia when                    the most useful for evaluating environmental
                            monitored at permanent stations orly. Since leaf               conditions. There may be some benefit in
                            width varies with shoot age as well as with                    sampling C:N:P ratios of macroalgae also. as an
                            environmental conditions, trends in other                      index of recent water-column nutrient
                            response and exposure indicators should be                     availability. Despite the ephemeral nature of
                            considered to help interpret any temporal                      macroalgal growth, repeated sampling over
                            changes in leaf width. Before leaf width is                    broad geographic areas might be useful to detect
                            considered as a geographic indicator. further                  patterns of nitrogen and phosphorus loading.
                            research is needed to quantify the spatial
                            van ability of this parameter       its relationship
                            to environmental gradients.                                    SPECIES COMPOSITION

                            Leaf Area Index: LAI integrates leaf size and                  The physical and chemical requirements of SAV
                            density and thus may be more responsive to                     species differ, making SAV species composition
                            stressors than leaf width alone. The effort                    a good indicator of environmental conditions.
                            required to determine LAI manually, however,                   The species composition of existing macro- and
                            reduces the utility of this measure for large-scale            filamentous algal communities can also yield
                            manual sampling. A meter that measures LAI by                  information on habitat quality. The presence of
                            light obstruction is currently used in terrestrial             Enteromorpha. for example, may indicate
                            systems and is adaptable for underwater                        nutrient-enriched waters. Little is known about
                            applications. Research is needed to determine                  the species response of epiphytic microalgae.
                            whether such a meter can be calibrated reliably                primarily diatoms. to specific conditions.
                               aquatic systems. Instrument-automated LAI
                            measures may thus be available in the future.                  DEPTH LIMIT

                                                                                           Declines in cover of submerged macrophytes
                            PLANT CONSTITUENTS                                             associated with degrading water quality usually
                                                                                           occur first at the deepest edge of the beds. The
                            Concentrations of soluble carbohydrates and                    depth limit of a grass bed is thus a reliable
                            ratios of C:N:P in plant tissue generally reflect              indicator of environmental quality; shoreward
                            environmental conditions. For example.                         migration of the edge of the bed over time
                            carbohydrate concentrations in 7halassia have                  indicates a decrease in the availability of light at
                            been shown to decline with light limitation.                   depth. Scuba diving is most often used to locate
                            Because concentrations of chemical constituents                the outer lirnit of a grass bed. Most of the
                            also show considerable seasonal variation,                     seagrass communities in the Gulf of Mexico
                            samples for comparative purposes must be                       exist in water shallow enough to use scuba for
                            restricted to similar times of year, plant growth              bed delineation. Alternatively. an underwater
                            phases, and tissue types. Although a long-term                 video camera can be mounted on a sled and
                            change in soluble carbohydrate concentrations or               pulled behind a boat. Use of remote sensing
                            C:N:P ratios at a site would indicate a change in              technology is the only practical technique for

                            Seagrass Monitoring and Research - 1992                                                                 'Page 46















                       locating the edge of deeper grass beds such'as                STRESS PROTEINS
                       those in Florida's Big Bend region. Side scan
                       sonar may offer a second remote sensing                       Stress proteins are a group of compounds that are
                       technique for determining the presence of                     highly conserved evolutionarily and that form in
                       vegetation in deeper waters. The potential to                 response to sublethal stresses. The use of stress
                       map distributions of seagrasses on the U.S. west              proteins &-, condition indicators stems primarily
                       coast has been investigated using this technique.             from crop research. where high levels have been
                       Further research is necessary to determine the                correlated with such stresses as anoxia and
                       applicability of side scan sonar to the Gulf of               repeated metal toxicity. The applicability of
                       Mexico. The mixed species composition of                      stress proteins for monitoring seagrass condition
                       seagrass communities may limit the utility of                 is unknown. Research is needed to determine the
                       this technique in Gulf waters. as it is unlikely              environnien!al factors and duration of exposure
                       that side scan images would allow species                     eliciting stress protein expression in seagrasses,
                       determinations.                                               as wel I as the thresholds of response indicating
                                                                                     degraded habitat conditions.

                       GENETIC DIVERSITY
                                                                                     ANIMALS
                       Ile magnitude of genetic variability within plant
                       populations is a function of en,,ironmental,                  Animals exert strong direct and indirect
                       demographic, and genetic v;ents. Genetic                      influences on many of the macrophyte
                       diversity is necessary for long-term persistence              parameters proposed as ecological indicators.
                       of populations and a6srstadon to changing                     For example. urchin grazing can directly reduce
                       environmental comitions. A decline in genetic                 leaf height and biomass. Alternatively, by
                       diver;ity may signal reduced resistance to                    controlling accrual of epiphyte biomass,
                       environmentai stresses and disease. Gel                       mesograzers can indirectly regulate macrophyte
                       electrophoresis surveys of specific loci have                 biomass, growth. and long-term survival The
                       been performed for seagrass beds. Although                    importance of higher order interactions in the
                       hiomolecular techniques for extraction and                    control of macrophyte dynamics argues for the
                       fingerprinting of scagrass DNA are currently in               inclusion of meso- and macrograzers in any
                       research and development stages, rapid advances               monitoring program; without information on
                       in forensic technology and applications suggest,              animal population densities it will he difficult to
                       that routine genetic processing of biological                 ascribe changes in macrophyte and epiphyte
                       material will soon be commercially available.                 characteristics unequivocally to habitat
                       ne incorporation of genetic diversity into a                  conditions. Grazers exhibit such extreme
                       seagrass monitoring program is dependent on the               temporal and spatial variability that
                       availability of technology to process large                   incorporation into a monitoring program using
                       numbers of samples for genetic composition.                   widely spaced, infrequent samples would yield
                       However,,starch gel electrophoresis of isozymes               little information. However, monitoring grazers
                       is well-established for Zostera marina and at                 concurrent with epiphyte and macrophyte
                       least 1000 samples a week can be processed                    parameters regularly (e.g.. monthly) at
                       easily.                                                       permanent stations representative of larger
                                                                                     geographic areas would, contribute substantially
                                                                                     to the understanding of local and regional habitat
                                                                                     trends.




                       Seagrass MonftonLnj and Research - 1992                                                                 Page 47











                                                                                                                                                                     r







                                  PRODUCTIVITY                                                    elucidation of the complex interrelationships
                                                                                                  among light availability, nutrient concentrations,
                                  Leaf productivity responds rapidly to changes in                epiphyte biomass and composition. macro- and
                                  environmental condit.ions, and it is                            mesograzer activity, and macrophyte response.
                                  straightforward, albeit labor-intcnsive, to
                                  measure using leaf-marking tectmiques. Because
                                  of seasonal variability in productivity, annual                 LIGHT
                                  sampling is insufficient to detect regional or
                                  long-term trends. If sampled at the appropriate                 The most important indicator of seagrass habitat
                                  time scale, however, this parameter may be one                  quality is the availability of photosynthetically
                                  of the most diagnostic early indicators of                      active iadialion (PAR) at depth. PAR should he
                                  environmental change. Monthly productivity                      monitored continuously at permanent stations.
                                  measurements at representative permanent                        The sampling array for each station consists of a
                                  stations would provide an excellent assessment                  data logger connected to two spherical sensors
                                  of local conditions.                                            offset vertically and separated h, '- 0.25 - 0.5 m.
                                                                                                  depending on water clarity (see also Morris and
                                                                                                  Tomasko 1993). The sensors will have to be
                                  EXPOSURE MICATORS                                               cleaned regularly. The frequency of
                                                                                                  maintenance visits required will be site specific-,
                                                                                                  the maximum interval between cleanings will
                                  Most of the parameters that stress seagrass                     probably be two weeks or less. Light is already
                                  populations exhibit extreme temporal variability,               monitored intensively at several sites in the Gulf
                                  so that single, annual samples would yield no                   of Mexico as part of ongoing research efforts.
                                  information on the extent of pollutant exposure                 EMAP should attempt to collaborate with these
                                  or habitat degradation present. Working group                   existing programs.-
                                  members agreed that the only way to quantify
                                  habitat quality in terms of many of the most                    Technology is also available for continuous
                                  important stress variables is by frequent                       monitoring of chlorophyll concentration and
                                  sampling or continuous monitoring at permanent                  turbidity. These measurements should be
                                  stations. The number of permanent stations                      coupled with light monitoring as funds permit,
                                  established would be dictated by funding.
                                  Station location should be stratified by degree of
                                  anthropogenic impacts. Sites close to urban                     NUTPUENTS
                                  areas are the most suscepdble to change, and
                                  sites away from urban areas can provide baseline                Nutrient enrichment enhances growth of
                                  data forIcomparison.                                            phytoplankton and epiphytic algae, and therefore
                                                                                                  can indirectly lirnit the amount of light reaching
                                  Although it is possible to list exposure variables              leaf surfaces. Dissolved nutrient concentrations
                                  that are correlated with seagrass health and                    are subject to considerable temporal variability,
                                  therefore should form part of a monitoring                      data are most meaningful if derived from
                                  program (Table 1), scientific understanding of                  frequent samples, Ideally, water quality should
                                  the causal relationships between multiple                       be measured at the same permanent stations used
                                  environmental stressors and macrophyte                          for,continuous light monitoring. ne need to
                                  response is limited. The need for further                       visit sites regularly for light sensor maintenance
                                  research to validate the proposed variables as                  provides at least biweekly opportunities to take
                                  exposure indicators cannot be overemphasized:                   water samples. Samples should be analyzed for
                                  the evolution of seagrass management requires


                                  Seagrass Monitoring and Research - 1992                                                                  Page 48
















                       total nitrogen. total phosphorus, nitrate,                   may be assisted by classifying sampling sites
                       ammonium, and soluble reactive phosphate.                    according to energy regime and sediment
                                                                                    characterisfics. Valuable data for such
                       To provide a spatial assessment of nutrient                  postsampling stratification include wave energy
                       concentrations and the potential sources of                  density. physical exposure index. effective fetch.
                       nutrient enrichment, frequent water quality                  tidal current velocity, sediment depth. sediment
                       sampling at a small number of sites should he                grain size distribution. and sediment carbonate
                       coupled with annual or semiannual sampling at                and organic contents.
                       all of the sites forming the EMAP network. All
                       nutrient sampling should be restricted to a 6-8
                       week window. The precise timing of nutrient
                       sampling should be determined from existing
                       records to minimize confounding effects of
                       temporal variability. Ideally, periods of
                       maximum and minimum runoff should both be
                       included for each site in order to identify
                       potential extremes of nutrient concentration,
                       Samples should be analyzed for chlorophyll in
                       addition to those nutrients identified for frequent
                       sampling.

                       DISSOLVED OXYGEN


                       The diel fluctuation in dissolved oxygen
                       concentration is  an index of ecosystem health.
                       Hypoxia limits secondary producers directly, and
                       effects may also cascade to seagrasses by
                       limiting grazers and consequently enhancing
                       epiphyte growth. Dissolved oxygen should be
                       measured continuously at each sampling site
                       long enough to characterize the magnitude of
                       diel variation and the duration of hypoxic
                       conditions. Pilot tests of up to a week of
                       continuous measurement should be undertaken
                       at a limited number of sites to determine an
                       appropriate monitoring interval for use in
                       regional sampling. Continuous PAR monitoring
                       at the same sites as oxygen measurement could
                       assist in interpreting temporal and spatial
                       patterns of oxygen concentration.



                       PHYSICAL CONDITIONS

                       Most of the seagrass parameters considered as
                       response indicators are affected by physical
                       conditions. Interpretation of response variables

                       Seagmss Monitoring and Research - 1992                                                               Page 49


















                                                                    REFERENCES


                          Morris, L. J. and D. A. Tomasko (eds.). 1993. Proceedings and conclusions (if workshops on: submerged
                             aquatic vegetation and photosynthetically active radiation. Special Publication SJ93-SPI3. Palatka,
                             IFL: St. Johns River Water Management District. 244 pp. + Appendices.

                          Summers, J. K., J. M. Macauley, and P. T. Heitmuller. 1991. Implementation plan for monitoring the
                             estuarine waters of the Louisianian Province - 1991 demonstration. EPA/600/5-91/228. U.S.
                             Environmental Protection Agency. Office of Research and Development. Environmental Research
                             Laboratory, Gulf Breeze, FL. 160 pp.




































                          Seagrass Monitoring and Research - 1992                                                    Page 50




















                               SUBMERGED AQUATIC VEGETATION
                                              RESEARCHNEEDS


                                       WORKING GROUP REPORT


                                                           by


                                                  William L. Kruczynski
                                                           and
                                                     David A. Flemer


                                          U.S. Environmental Protection Agency
                                           Environmental Research Laboratory
                                                      Sabine Island
                                                  Gulf Breeze, FL 32561















                 Seagrass Monitoring and Research - 1992                                      Page 51















                             The purpose of this portion of the workshop was              may he proportional to nutrient concentr.at ions.
                             to identify and prioritize research requirements             Thus. although there is agreement that light is
                             for submerged aquatic vegetation (SAV)                       the principal controlling mechanism. it is
                             ecosystems and give some direction to the U.S.               necessary it) quanfify the relationship hetween
                             Environmental Protection Agency concerning                   light, nutrients. phytoplankton standing crop and
                             which research issue could be addressed with                 species composition. suspended sediments.
                             1992 fiscal year funds. This working group also              color. macroalgae and epiphyte standing crop
                             discussed problems associated with designing,                and specie-, composition. and grazers for each
                             implementing. and interpreting an assessment                 SAV community in different geographic areas,
                             program (Environmental Monitoring and
                             Assessment Program; EMAP) for SAV                            Research to establish the minimal ecological
                             communities..                                                requirements must be multifaceted and should
                                                                                          proceed in two directions to determine:

                             ESTABLISHMENT OF                                             0 Ile causes and mechanisms of light
                                ECOLOGICAL LIMITS                                         reduction; and.

                                                                                          0 How plants and their community respond to
                             There was general agreement among the                        changes in the quality and quantity of light and
                             members of the working group that the quality                other ecological stressors.
                             and quantity of light are the principal ecological
                             factors that control the presence and growth of              Information is needed on the effects of stressors
                             SAV and that light requirements for subtropical              on plant morphology and carbon balance. Also,
                             SAV species have not been adequately                         the association between nutrients and light
                             determined. Also, the minimal ecological                     availability must be quantified.
                             requirements for establishment and growth of
                             SAV species are species-specific and may vary                Research must @be 'performed in the field and in
                             geographically within the range of a species.                the laboratory (mi-rocosms and mesocosms)
                             Data on northern species (e.g.. Zostera in                   through manipulation of environmental
                             Chesapeake Bay) are not directly transferable to             variables. Results must be modeled and their
                             predictive models for southem, subtropical                   predictability tested. Research is required on
                             systems (e.g., Vialassia in Florida Bay). Many               development of culture methods for subtropical
                             more species of SAV exist in warmer waters,                  species of seagrasses before mesocosms can he
                             which compounds the problem of establishing                  used to establish and test limits to growth.
                             ecological limits for SAV communities. Further,
                             species found in coastal waters stained by
                             organic acids probably have different ecological             RESTORATION
                             requirements than do different species or the
                             same species growing in spring-fed waters.                   Restoration and creation of Thalassia and other
                             Light requirements cannot be considered alone.               SAV communities was discussed at length and it
                             because the availability and quality of light are            was concluded that there are no documented
                             controlled by other environmental factors.                   examples of successful replacement of a
                             Absorption of incident light can occ-ir as a result          71lialassia community. Once Thalassia
                             tef water column attenuation and macroalgae-                 disappears from an area, it will take a long time
                             epiphyte attenuation. The amount of light-                   for that area to recover. The reasons for poor
                             absorbing phytoplankton and epiphytic growth                 recovery. whether the area is planted or not. are

                             Seagrass, Monitoring and Research- - 1992                                                            Page,52















                    many and complex. Resuspension of sediments                   The second research pToject discussed concerned
                    in unvegetated are&s and changes in sediment                  establishment of the absolute maximum depth
                    chemistry are primary factors that inhibit                    for each SAV species throughout its geographic
                    colonization by Thalassia. The working group                  range. Physical wid chemical measurements
                    concluded that all existing 77talassia meadows                taken over the depth distribution could he used
                    must he preserved and that no losses of "climax"              to establish minimurn ecological requirement.,;
                    SAV species caused by development should he                   for each species,
                    tolerated.
                                                                                  General concern was expressed over
                    Hatodule is a pioneer species of seagrass that                extrapolation of measurements @wd observations
                    may recolonize a site within several growing                  determined on tine scale to other scaics. It was
                    seasons. Once a bed (if Halodisle is established.             agreed that scaling experiments must he
                    so:diments become stabilized and the area may he              performed before generating predictive models
                    invaded by Thalassia. Species. population. and                based upon site-specific observations or
                    community responses during declire may not he                 mesocosm manipulations.
                    the same as those observed during recovery of an
                    SAV community. Research is required to define                 The following is a list of the highest priority
                    optimum conditions for revegetalion by SAV                    SAV research given by each member of the
                    species and determine plant. population, and                  working group. Although specific research
                    community parameters indicative of declining                  topics were later consolidated into broader areas.
                    and recovering systems.                                       there is a N-nefit in reproducing the complete list
                                                                                  here to identify the range of specific topics that
                                                                                  were identified. Also, although many topics
                    SPECIFIC RESEARCH TOPICS                                      listed appear nearly,duplicative. there is a benefit
                                                                                  inlisting the slightly different emphasis that
                                                                                  differew scientists gave to areas of similar
                    The working group identified    'specific research            concern.
                    projects for consideration for future funding, two
                    of which were discussed in some detail. First, it
                    was suggested that a detailed mapping and
                    monitoring program could be used to identify                  Priority Research Topics
                    research priorities. If SAV communities are                      1.   Quantify minimum and optimum
                    mapped on a regular basis. areas of decline. may                      physical and chemical requirements for
                    he detectable before vegetation completely                            all SAV species.
                    disappears. Research could then be initiated to
                    assess ecological conditions and identify                        2.   Quantify the link between nutrient input
                    indicators of stress at various levels of ecological                  and light regime in different near-coastal
                    organization. It was noted that there appears to                      systems.
                    be a strong empirical correlation between
                    presence of fringing emergent wetland                            3.   Establish the "lethal dose" that results in
                    communities and presence of SAV communities.                          a declining SAV community.
                    Regional mapping efforts are required to
                    substantiate this observation and, if documented.
                    research must be performed to establish the                      4.   Identify the suite of environmental
                    mechanisms controlling this phenomenon.                               variables that best predicts the @
                                                                                          abundance and survival of SAV species.




                    Seagrass Monitoring and Research - 1992                                                               Page 53
















                             5.   Identify and quantify combinations and                       flowering. Is increased flowering an
                                  interactions of environmental parameters                     indicator ofstrcss'?
                                  that control SAV distribution and
                                  abundance.                                              15.  Niap distribution of SAV species over
                                                                                               the entire region and overlay with
                             6.   Identify the interaction of suhlethal and                    regioral maps of depth. currents.
                                  lethal effects on SAV communities that                       nutrient loadings. sediment plumes. and
                                  are associated with water and sediment                       other siressors. Use mapping exercise a-,;
                                  quality.                                                     a hypothesis-gencrating tool and
                                                                                               determine multivariate response surface
                             7.   Investigate mechanisms of recovery of                        for each species.
                                  seagrass ecosystems including
                                  comparison of the relative importance of                16.  Analy7c all existing information and
                                  sexual and asexual propagation and                           make best estimate on indicators of
                                  community succession.                                        stress and thresholds.

                             8.   Determine whether remotely sensed sea                   17'.. Investigate the potential impact of
                                  turtle distribution can be used as an                        changes in sea levels to stagrass
                                  approximation of distribution of                             distribution.
                                  seagrasses.
                                                                                          18.  Determine the framework for
                             9.   Assess the usefulness of carbon balance                      extrapolation of measurements made on
                                  of plants in detecting stress caused by                      one scale to other scales.
                                  subtle changes in water or sediment
                                  chemistry that may otherwise be                         19.  Investigate the biology and ecology of
                                  undetectable.                                                Halophila spp. Species of Halophila
                                                                                               have not received much research
                             10.  Monitor genetic differences within a                         attention and maj be important to
                                  plant species, because they may result in                    sediment stability. food chain
                                  regional differences in tolerance of                         productivity. and ecosystem dynamics.
                                  physical and chemical parameters.
                                                                                      Research topics were grouped into rive main
                             11.  Investigate the intensity of plant                  areas and summary statements were made to
                                  reponses to alterations of light quantity           consolidate individual areas of concern. Major
                                  for SAV species.                                    areas of required research were summarized in a
                                                                                      model that identifies important stressors to SAV
                             .12. Quantify response of entire seagrass                ecosystems (Fig. 4). Research efforts are
                                  community, including fisheries                      required to identify and quantify responses at
                                  productivity, to nutrient loading.                  various levels of ecological organization to
                                                                                      environmental stresses. including determination
                             13.  Quantify the effects of epiphytes.                  of thresholds.
                                  epiphyte grazers, and macroalgae on
                                  seagrass survival and growth.                       1. Physiological responses of plants to
                                                                                          ecological factors.
                             14.  Determine the impact of stressors on the
                                  balance of vegetative multiplication and                     a.      Determine the physiological
                                                                                                       responses of SAV species to

                         Seagrass Afoniloring and Research - 1992                                                             P@ge 54'




















                                         various levels of stresses.  Does                              over?
                                         plant sensitivity change                                      0 Does Halophila enhance
                                         seasonally?                                                    hiodiversity and abundance?
                                                                                                       * Is it a good indicator of
                               b.        Identify a suite of plant-level                                ecological conditions!
                                         responses.to evaluate sublethal
                                         stresses so that environmental                       C.       Investigate the effects of
                                         controls can he implemented                                   macroalgae in light attenuation.
                                         before thresholds of population
                                         decline and change in                                d.       Determine the relationship
                                         community structure are                                       between nutrient levels and
                                         reached,                                                      community structure.

                               C.        Investigate the interaction                    4.    Mapping exercises.
                                         hetween light intensity and light
                                         quality.                                             a.       Develop regional maps of SAV
                                                                                                       distribution and physical and
                               d.        Determine the response surface                                chemical parameters to generate
                                         of SAV to temperature, salinity,                              hypotheses and predications
                                         and 'light.                                                   concerning the effects of
                                                                                                       stressors.
                      2. Responses at population level.
                                                                                        5.    Overriding factors.
                               a..       Quantify the species-specific,
                                         water quality and light                              a.       Research is required to
                                         requirements and their                                        distinguish between natural and
                                         interaction on long-term                                      anthropogenic changes in
                                         maintenance and establishment                                 seagrass distribution and
                                         of SAV species.                                               community structure. Natural
                                                                                                       cycles and ir pacts of episodic
                               b.        Determine the mechanisms of,.                                 events must be considered.
                                         recruitment.                                                  Analysis of long cores may be
                                                                                                       useful in detecting changes in
                          3.   Responses at community level.                                           community structure and
                                                                                                       correlating with historical
                               a.        Determine the interaction of                                  events. Does succession or do
                                         epiphytes. epiphyte grazing.                                  episodic events control species,
                                         and nutrient loading on growth                                dominance? What is the
                                         and survival of SAV species.                                  temporal scale of responsc?

                               b.        Investigate ecological variables                     b.       The management    policy should
                                         and functions of communities                                  he no net loss of climax SAV
                                         dominated by Halophila spp.                                   species because conditions
                                                                                                       required for their recruitment are
                                         9 Does Hatophila stabilize                                    difficult or impossible to
                                          sediments?                                                   replicate.
                                         0 How rapidly does it turn


                      Seagrass Monitoring and Resiarch               1992                                                     Page 55

















                                                                        Geographic CoveraL:e/D;s:r,bu1iyn
                                                                                  M a pp ing Exercise









                                                                       j -0(-"hot spots"


                                                                                    /V                       N'tinimum and OPI-MLIM
                                                  Watershed                                                  Light Requirnnerr,
                                                   Impacts



                                                                                                                Color4)
                                                                                                                Macroalgae
                                                                                                                Phytoplankton
                                                        'Spec es   -                                            Epiphytes
                                                         Specific
                                                        .@hanges                                                Total 'Suspende
                                                                                                                 Solids




                                                                                    e. g., Halol)hild sp.


                                                                     Facrors@
                                                                     Dissolved oxygen           V    --Er);Ph,. !es
                                                                     Carbon dioxide               414'f Produ
                                                                     Temperature                     Ca(hor,-
                                                                     5'.1611V
                                                                     Nutrients
                                                                     Toxins


                                                                                                      L o s s








                                             Figare 4. Summary of areas nf research emphasis for SAV communlUeq. All areas must considerscale. time.
                                             and space components.





                           Seagrass Monitoring and Research - 1992                                                               Page 56

















                                        c.       It is necessary to determine the.            environmental assessment program must be
                                                 effects of watershed                         sensitive to the fact that it is extremely difficult
                                                 management and nutrient and                  it) distinguish changes that result from
                                                 salinity effects on light regimes            andiropogenic causes. natural successional
                                                 in estuaries and near coastal                processt--s. or long- or short-jern) variations in
                                                 waters.                                      climatic conditions. In many cases, there is not
                                                                                              enough information on (he response of SAV
                                        d.       Scaling considerations are                   species to various stressors to determine the
                                                 necessary.to allow confidence in             causalio of SAV decline. For example-allhough
                                                 predictive models.                           disease (e.g.. caused by LabYrinthula sp.) is
                                                                                              known to play an important role in the demise of
                                        e.       The effects of meadow                        celgrass (Zosiera) (in the North Atlantic coast
                                                                                                                                 -ase organisms
                                                 fragmentation on ecosystem                   and Europe, it is no( clear if dise
                                                 function must be deteimined.                 play a similar role for subtropical seagrass,
                                                 What is the minimum patch                    species. Further. the association between other
                                                 size? Do many smV patches                    environmental stresses and incidence of disease
                                                 funcdon as wel! as a continuous              must be determined and quanfified.
                                                 meadow?
                                                                                              A monitoring and assessment program must also
                                        f.       New and emerging technologies.               be sensitive to the fact that SAV species may
                                                 such as DNA fingerprinting.                  respond to stressors slowly and (hat
                                                 should be applied to seagrass                environmental conditions observed when the
                                                 communities.,                                decline is observed may not represent the same
                                                                                              conditions that initiated the decline. Because of
                                        g.       Genetic diversity of-SAV                     this time lag. natural SAV communifies may not
                                                 species must be maintained in                be goood indicators of current environmental
                                                 transplant efforts.                          perturbations. However. they are excellent
                                                                                              integrafive indicators of long-term ecological
                                                                                              conditions.
                               ENVIRONMENTAL ASSESSMENT

                               Environmental assessment programs (e.g..'
                               EMAP) must be carefully designed so that they
                               have the sensitivity required to detect changes
                               (deterioration or improvement) in environmental
                               conditions. Careful consideration must be given
                               to the selection of ecological indicators to assess
                               the status of the "health" of SAV ecosystems.
                               'Me nature of environmental problems and their
                               indicators may change with regions and Vmies.
                               IMus, preparing a plan to assess the status of
                               seagrasses; in a large geographical area is not a
                               simple mauff.

                               Once a problem has been identified, the next Step
                               is to determine the causes of the problem. An


                               Seagrass Monitoring and Research - 1992                                                                  Page 57-












                                                                                                                          r

















                                   SEAGRASS CONSERVATION IN THE
                                                 GULF OF MEXICO:
                                               AN ACTION AGENDA


                             SUMMARY OF WORKING GROUP REPORTS


                                                               by


                                                        Hilary A. Neckles

                                                   National Biological Survey
                                                    Southern Science Center
                                                      700 Cajundome Blvd.
                                                      Lafayette, LA 70506















                    Seagrass Monitoring and Research - 1992                                       Page 59

















                              Following a day and a half spent summarizing                  Works  hop participants reconvened in a plenary
                              knowledge of mapping. monitoring, and research                session to consolidate the four groups of
                              on seagrass habitats, workshop participants                   conservation objectives into a single aclion
                              reorganized to translate this information into                agenda. The following actions were concluded
                              specific actions necessary to reduce habitat                  to represent the four highest priority ol@jectivcs
                              degradation. Four working groups met to                       for conservation of Gull'of Mexico scagrass
                              address the question, "What can our agencies and              systems.
                              institutions do together to begin, to reverse the
                              trend of seagrass loss in the Gulf of Mexico?"
                              Each group was asked to develop, by consensus,                ESTABLISH A POLICY OF NO
                              a list of the four highest priority actions for                   SEAGRASS LOSS
                              seagrass conservation. Proposed actions were to
                              adhere to the following four criteria: 1) actions             The National Wetlands Policy Forum
                              must lead to significant habitat improvements; -
                              2) it must be possible to verify or measure                   recommended that United States adopt a policy
                              whether actions have been accomplished. 3)                    of "no net loss" of wetlands. to be achieved
                              responsible parties must be willing and able to               through compensatory mitigation for all
                              undertake the proposed "ctions. and 4) any                    permitted habitat conversions. This poijzy
                              necessary financial resources must be available.              implies a 1: 1 replacement for all permitted losses
                              Yorking groups were given 1.5 hours to produce                so that the net wedand acreage remains constan!.
                              their lists. The short time frame serveJ to focus             It is exceedingly difficult, however. to
                              working group attention on the most urgent                    successfully establisli seagrass beds, so that
                              conservation needs.                                           compensatory mitigation has not yet been
                                                                                            effective for this habitat. The best way to ensure
                                                                                            no ne! !oss of seagrass systems is thus to avoid
                              As a springboard for discussion, each working
                              group developed a fairly exhaustive list of                   impacts altogether. Written policy must allow
                              potential conservation actions. Individual                    no loss of existing seagrass communities
                              suggestions fell into the categories of water                 through any permitting programs. This is
                              quality improvement, public education, habitat                particularly important in the case of Thalassia
                              restoration, regulation. enforcement, research,               beds. which are the most difficult to establish
                              coordination, monitoring, and seagrass                        through planting. 71alassia population growth
                              sanctuaries. Various approaches were used                     and coverage rates are very slow, so that it takes
                              within working groups to reach a consensus on                 many years for transplants to coalesce. The
                              the top priorities, including combining like                  potential for physical disturbance, biolurbation.
                              statements into inclusive conservation objectives             and depletion of fauna in the interim further
                              and ranking proposed actions by democratic                    reduces the likelihood of establishing a
                              vote. The final lists from each working group                 functional Thalassia meadow through
                              are presented in Appendix 1.                                  transplanting. Therefore, permitted conversions
                                                                                            of Thalassia beds invariably result in a net loss
                              As evidenced by the high degree of overlap                    of seagrass. To date, no examples of successful
                              among the lists generated independently by each               replacement of 7halassia habitat have been
                              work group. seagrass expens generally agree on                documented. The only way to avoid reductions
                              the immediate courses of action necessary to                  in total Thalassia acreage through the permit
                              reverse habitat losses in the Gulf of Mexico.                 process is to stop all permitted losses.


                              Seagrass Monitoring and Research - 1902                                                                Page 60


















                                                                                       designed not only to disseminate informition,
                        IMPROVE WATER QUALITY                                          but also to encourage public participation in
                                                                                       seagrass conservation. For example. regional
                        The primary cause ot&clines in seagrass habitat                and local programs should he developed to
                        is deterioration of water quality. Restoration of              includu citizens in monitoring and re-,;toration
                        seagrasses to historical levels in the Gulf of                 activities. The words (if a vocal seagrass
                        Mexico will require widespread water quality                   constituency can translate into legislative
                        improvements, which in (um will require                        support for necessary conservation measures.
                        reduction of anthropogenic nutrient and
                        sediment loading. Nblic and legislative support
                        for necessary changes in watershed management                  FORM A SEAGRASS WORKING
                        could be gained through the development of                        GROUP TO DEVELOP POLICY
                        demonstration projects linking specific                           AND IMPLEMENT DECISIONS
                        reductions in nutrient discharge or sediment
                        inputs with seagrass recovery. Research is                     Effective seagrass conservation requires the
                        needed to define the minimum water quality                     cooperative efforts of Federal, State. and local
                        requirements of subtropical seagrass species and
                        the sources of water quality degradation. thereby              agencies, research institutions. and various user
                        providing targets for management efforts.                      groups. A coordinated approach to Gulf (if
                        Minimum water quality requirements can be                      Mexico scagrass habitat conservation should be
                                                                                       formalized through establishment of a working
                        derived from empirical relationships between                   group representing all interests. A lead
                        water quality gradients and seagrass distribution.
                                                                                       coordinating agency must be selected to
                        as has been done in the Chesapeake Bay
                        (Dennison et al. 1993), and the factors                        facilitate interaction among representatives and
                        contributing to water column light attenuation                 to act as a clearinghouse for information: The
                        can be determined from models relating optical                 SAV Working Group of the Chesapeake Bay
                        properties of the water to specific water quality              Program serves as a model for coordinated
                        parameters (Gallegos eta]. 199 1). Experimental                efforts of scientists, resource managers,
                        research should be promoted to elucidate the                   politiciansi and the public. collaboration among
                        causal relationships between environmental                     the interest groups resulted in the development
                        variables and seagrasses at various temporal and               of baywide ard regional submerged aquatic
                        spatial scales.                                                vegetation water quality requirements and
                                                                                       distribution restoration targets (Batiuk et al.
                                                                                       1992).

                        DEVELOP PUBLIC EDUCATION
                           PROGRAMS


                        Ugislative initiatives to protect and restore Gulf
                        of Mexico seagrass communities depeLA
                        ultimately on strong public support. Education
                        programs must be developed to increase public
                        awareness of and appreciation for the ecological
                        and economic values of seagrass habitats. Public
                        appreciation for natural resources is enhanced by
                        involvement. Programs should therefore be


                        Seagrass Monitoring and Research - 1992                                                                  Page 61


















                                                                     REFERENCES


                            Batiuk.R.A..R.J.Orth.K.A.M(x)rc,W.C.IXnnison.J.C.Steveilslwr.l..W.Siztvcr.V.(,arier.N.B.Rybicki.
                               R.E. Hickman, S. Kollar, S. Bieber. P. Heasly. 1992. Chesapeake Bay submerged aquatic vegetalion
                               habitat requirements and restoration targets: A technical synthesis. U.S. Unvironmental Proleclion
                               Agency, Chesapeake Bay Program, CBP/TRS 83192.

                            Dennison. W.C., R.J. Ch1h. K.A. Moore, J.C. Stevenson. V. Carter. S. Kollar, P.W. Bergstrom. and R.A.
                               Batiuk. 1993. Assessing water quality with submersed aquatic vegetation. Bioscience 43:96-94.

                            Gallegos, C.L., D.L. Correll, and I Pierce. 1991. Modeling spectral light available to submerged aquatic.
                               vegetation, Pages 114-126 jjU W.J. Kenworthy and D.E. H-3unerl (eds.). The light requirements of
                               seagrasses: proceedings of & workshop to examine the capability of water quality criteria. standards and
                               monitoring programs to protect seagrasses. NOAA Technical Memorandum NMYS-SE-FC-287.



































                           Seagrass Monitoring and Research - 1992                                                    Page 62

















                                                               APPENDIX A



                    Highest priority actions for seagrass conservation in the Gulf of Mexico. as determined by individuaI
                    working groups.


                    Group I

                       ï¿½ Develop, fund, and implement cost-effective sewage and storm water treatment Systems.

                       ï¿½ Establish a written seagrass policy and an implementation plan including research. agency. and
                          public interests.

                       ï¿½ Develop a baseline of information on seagrass distribution and abu ndance for the Gulf of Mexico.

                       0, Develop and coordinate a system of citizen advisory, public education, and monitoring groups
                          across the Gulf of Mexico.

                    Group 2

                       0  Demonstrate the linkage between improvements in point source discharges and seagrass community
                          response at specific sites..

                       0  Reduce point source and non-point source nutrient and sediment loading to attain defensible.
                          historical values of light attenuation for individual estuaries.

                       0  Develop legislative and public support for seagrass systems through education.

                       0  Require that local comprehensive plans include potential impacts to seagrass ecosystems.

                    Group 3

                       0  Actively support the preservation and restoration of seagrass habitats.

                       0  Establish a seagrass management working group with scientific. management, regulatory, and user
                          group representatives to devel - p policy and a strategic management plan for the Gulf of Mexico
                          grassbeds.

                       0  Build a seagrass constituency by increasing public and user group appreciation of the importance of
                          Seagrasse.s.

                       0 Improve the water quality of seagrass habitats.




                    Seagrass Monitoring and Researeh         1992                                                Page 63
















                                 (Appendix A, continued)


                                 Group 4

                                    0 Change no net loss to no lois of seagrassLs because miligation and enforcement are not effective.

                                    * Promote experimental research and mapping at various scales to determine causes of habila, loss.

                                    0 Revise and enforce water quality criteria to protect submerged aquatic vegetation.

                                    * Encourage enforcement of existing laws. policies, and rules through public education.



































                                Seagrass Monitoring and Research - 1992                                                     Page 64






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