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









              EVALUATION OF GREAT MARSH POND COMPLEX





                      Delaware Division of Fish and Wildlife
            Department of Natural Resources and Environmental Control




   



                                                         
                            Prepared by Randall V. Cole
                            Fish and Wildlife Scientist

                                    August 1991


         QH
         541.5
         S24     through Federal Grant from the office of Coastal Zone
         C65      ent, NOAA under provision of Section 306 of the Coastal
         1991        Zone Management Act of 1972 as amended.
 












                                 TABLE OF CONTENTS




              Acknowledgements . . . . . . . . . . . . . . . . .

              Introduction . . . . . . . . . . . . . . . . . . .   1 - 9


              Waterbird Utilization  . . . . . . . . . . . . . .  10 - 56


              Water Quality . . . . . . . . . . . . . . . . . .   57 - 73

              Emergent & Submergent  Vegetation . . . . . . . . . 73 - 84

              Invertebrates . . . . . . . . . . . . . . . . . .   84 - 93

              Brood Survey . . . . . . . . . . . . . . . . . . .  93 - 94

              Fish Populations . . . . . . . . . . . . . . . . .  95 - 96

              Mosquito Reduction . . . . . . . . . . . . . . . .    97

              Discussion & Recommendation  . . . . . . . . . . .  98 -101


              References . . . . . . . . . . . . . . . . . . . .    102








                                Acknowledgments


             The list of acknowledgments to the people who have

        contributed to the research concerning the Great Marsh Project is

        lengthy. Many man-hours were necessary to accomplish the various
        tasks during inclement weather from below freezing to 900,

        thunderstorms to hurricanes and gnats to greenheads. These tasks

        could not have been completed without the support from personnel

        in the wildlife section, mosquito control and fisheries section.

        Many thanks go out to the full-time observers who participated tm-

        the entire four-year period' Bill Whitman, Tom Whittendale, Bill

        Jones, Roger Wolfe, Rob Gano and Harry Schellenger. Also, Dave

        Saveikis, who was involved with the project from the beginning

        and left to accept another position. Other people who greatly

        contributed voluntarily are Terri Fabean, John Clark and three

        seasonal employees Matt Higgins, Shawn Shotzberger, Nancy Goggin

        and Bob Palmer. Additional help was received from Stew Michels,

        Craig Shirey, Bill Meredith and Greg Moore.










                                   INTRODUCTION



             The Great Marsh, located in Lewes, Delaware (Fig. 1) is the

        site of a 5 year research project funded by Coastal Zone

        Management Act. The Division of Fish and Wildlife is studying

        the effects of Integrated Marsh Management (IMM) on waterbird

        utilization and production, invertebrate populations, submergent

        and emergent vegetation, water quality, fish populations, and

        mosquito reduction. Consisting of 2300 acres of tidal salt

        marsh, the Great Marsh was intensively grid-ditched for mosquito

        control in the 1930's and again in the mid-19601s. These ditches

        were indiscriminately placed at 150 ft. intervals, thus

        effectively draining many ponds which held permanent water (Fig.

        2). After grid-ditching on the Great Marsh, non-tidal pond areas

        decreased from over 40 acres in 1926 to 10 acres in 1979. Many

        ponds were drained as a result on grid-ditching, however some may

        have been drained naturally (i.e. muskrat burrowing). These

        ponds, which one provided desirable habitat for wintering and

        breeding waterfowl and numerous waterbirds are now dewatered due

        to direct tidal connection. The Great Marsh once had many non-
A       tidal ponds which provided important habitat for waterfowl and

        other waterbirds. These experimental ponds serve to reverse the

        detrimental effects of draining by putting permanent standing

        water back on the tidal marsh. Each pond provides habitat for

        feeding and resting waterbirds during various times of the year.

        The Great Marsh once was considered prime habitat for the

        declining black duck, providing good opportunities for hunting.

        In keeping with the nation's policy of "no net loss", it is






















                                                                                       no
                                                    STUDY SME L,'Or,,.;ATU




















                             Figure 1. Great Marsh study  site location























































                              Figure 2. Ponds Affected by Grid Ditching









                                            3









        important to understand the function and value of restoration and

        creation of pond habitat to return a degraded marsh to its

        original values or to enhance a marsh lacking adequate available

        water habitat. These results will be used to determine the


        feasibility of routinely including similar ponds within OMWM

        (Open Marsh Water Management) projects to achieve integrated

        multiple use wetlands management.

             One of the main objectives of the study is to enhance

        wildlife habitat through creation and restoration of ponds on

        degraded marshes. This maintains a stable habitat and provides

        feeding and refuge areas for numerous species (including

        waterfowl, shorebirds, wading birds, gulls and terns), both in

        quantity and quality important in terms of recreational hunting,

        bird watching and nature study.

             In 1986, twelve experimental sites were selected for

        evaluation. Spartina alterniflora is the dominant emergent

        vegetation covering low-marsh areas and along tidal creeks and

        ditches. Salt hay consisting of S. patens and Distichlis spicata

        occurs in isolated areas of the open marsh, along the upland

        fringe, and in areas fringing wooded hummocks. Shrub species

        including Iva frutescens and Baccharis halimifolia occur on many

        of the ditch spoil mounds and upland areas. Phragmites australis

        occurs in small, isolated bands and patches along the upland

        edge. Stands of Typha and Scripus are found in scattered areas.

        Seven sites were chosen in areas of multi-depression, high

        density mosquito breeding habitats (salt hay habitat), three in

        non-mosquito breeding habitat (S. alterniflora habitat), and two



                                   4









         ponds that were previously drained by grid ditches were restored

         by plugging the outlets. Another areas was treated with OMWM

         techniques. These techniques usually rely on small ponds (one-

         tenth of an acre or less) and ditches to eliminate breeding areas

         and allow small killifish access to mosquito larvae. However, in

         order to combine wildlife needs in conjunction with the objective

         of controlling mosquitoes, the ponds were enlarged to

         approximately one-half acre. The ponds were constructed with

         curvilinear sides for a natural appearance. The 12 installed

         ponds at Great Marsh account for approximately five acres, so

         there remains a let loss of 25 acres of non-tidal ponds when

         compared to pre-grid ditched. These ponds will help mitigate the

         loss of natural non-tidal ponds lost to grid-ditching.

              A variety of equipment was used in construction including a

         crane, backhoe, bulldozer, and a rotary excavator. The ponds

         were dug to a depth of 4-18" with a 3 foot sump to serve as a

         fish reservoir during drought periods. This shallow depth also

         serves shorebirds and wading birds and allows enough light

         penetration to allow the growth of submerged aquatic vegetation

         (SAV). The resultant spoil is spread over the marsh surface with

         a final increase above original marsh elevation of approximately

         2-4". The natural tidal ponds were plugged with spoil material

         to block direct tidal drainage and flooding. The controls

         included natural areas of marsh not affected by construction

         which contains flat pans which hold water during flood-over

         events and after heavy rain, and areas of contiguous marsh

         containing little or no water habitat. Two areas (Cl and C2) are


'A
                                    5







         completely vegetated with salt hay and S. alterniflora: C3A and

         C3B are areas of S. alterniflora with numerous small flat pans

         and tidal ponds; and the last control area (C4) is dominated by

         S. alterniflora with two small flat pans. Various experimental

         construction techniques were employed including semi-tidal

         systems in salt hay (ponds 5 and 7) and S. alterniflora (pond 3),

         closed systems in salt hay (ponds 2, 6 and 8) and S. alterniflora

         (ponds 4 and 12) and restored closed (pond 9) and restores sill

         (pond 10). Islands were constructed in ponds 2, 3, 4, 5, 6, 7,

         and 8 to promote nesting and reduce the amount of spoil deposited

         on the marsh surface.

              In 1987 four 15-foot scaffolding towers were erected,

         positioned to have full view of 10 of the 12 ponds plus the OMWM

         site and the 5 control areas adjacent to the ponds (Fig. 3). The

         controls included areas which contain flat pans which hold water

         during flood-over events and after heavy rain, and areas of

         contiguous marsh containing little or no water habitat. Each

         pond and control area was measured and staked to provide equal

         area of viewing. There is a total of 16 observation areas - 10

         ponds, 5 control areas and the OMWM site. The observation areas

         are observed for 2-hour periods on randomly selected days with

         equal dawn and dusk time frames. Every 15 minutes the observer

         would scan each area and record the species and the number of

         individuals utilizing the area within the staked boundaries and

         also its behavior and specific habitat being used. During the

         first year, 60 observation periods were scheduled from April

         through early December. Based on the first year of observations,



                                    6
























                                                '44







































                                    Figure 3. Observation Tower





                                           7








        the number of observation periods were decreased to 34 from mid-

        February through November for the remainder of the project.

        These dates concentrate on peak migratory periods for waterfowl

        and shorebirds.

             During the four years of observation, a total of 54 species

        from four guilds have been recorded utilizing the areas:

        waterfowl - 15, shorebirds - 20, wading birds - 10, and gulls and

        terns - 9. Two miscellaneous species, kingfishers and osprey

        have also been observed using the ponds (Table 1). Although

        waterbird utilization was of primary concern, other important

        parameters assessed relating to pond quality and ability to

        attract waterbirds are invertebrate populations, emergent and

        submergent vegetation, fish populations, brood production, and

        water quality. In addition, the ability of the ponds and

        surrounding area to control mosquitoes was determined.


























                                   8








         Table 1. ..SPECIES LIST FOR GREAT MARSH BY SPECIES GUILD
         ----------------------------------------------------------------


                                     WATERFOWL

                                 -----------------


         BLACK DUCK                               HOODED MERGANSER
         MALLARD                                  WOOD DUCK
         GADWALL                                  RUDDY DUCK
         BLUE-WINGED TEAL                         PIED-BILLED GREBE
         GREEN-WINGED TEAL                        WIGEON
         RED-BREASTED MERGANSER                   BUFFLEHEAD
         COMMON MERGANSER                         DOUBLE-CRESTED CORMORANT
         NORTHERN MERGANSER         SHOREBIRDS
                                ------------------



         WILLET                                   DUNLIN
         GREATER YELLOWLEGS                       SOLITARY SANDPIPER
         LESSER YELLOWLEGS                        SPOTTED SANDPIPER
         BLACK-BELLIED PLOVER                     RUDDY TURNSTONE
         SEMIPALMATED PLOVER                      WILSON'S PHALAROPE
         KILLDEER ,                               MARBLED GODWIT
         LEAST SANDPIPER                          PECTORAL SANDPIPER
         SEMIPALMATED SANDPIPER                   NORTHERN PHALAROPE
         SNIPE                                    STILT SANDPIPER
         SHORT-BILLED DOWITCHER                   BLACK-NECKED STILT


                                   WADING BIRDS

                               --------------------


         GREAT BLUE HERON                         GREAT EGRET
         TRI-COLOR HERON                          GLOSSY IBIS
         LITTLE BLUE HERON                        CLAPPER RAIL
         GREEN-BACKED HERON                       VIRGINIA RAIL
         SNOWY EGRET              GULLS AND TERNS AMERICAN BITTERN
                              -----------------------


         GREATER BLACK-BACKED GULL                LEAST TERN
         LAUGHING GULL                            COMMON TERN
         HERRING GULL                             FORESTER'S TERN
         RING-BILLED GULL                         LITTLE TERN
         BLACK-CROWNED NIGHT HERON



                                   MISCELLANEOUS

                               ---------------------


         KINGFISHER                               OSPREY






                                    9










                               WATERBIRD UTILIZATION


              Four scaff olding towers serving as observation blinds were

         erected in March 1987. Observations began on April 1 and

         continued through late-fall, early winter. Adjustments in

         rescheduling were made to concentrate on peak migratory periods

         to best utilize man-power. A total of 176 2-hour observations

         were scheduled from 1987-1990. A few had to be cancelled due to


         environmental factors such as flooded conditions on the marsh


         surface, heavy fog and lightning.

              As one may expect, the data results are highly variable due

         to high and low pulses within the data caused by the mobile

         nature of the species being observed, weather factors, time of

         day, and migratory periods. Due  to this high variability, the

         data will be assessed qualitatively via a relative use index. It

         was felt that just counting individuals was inadequate because

         utilization of the ponds over a period of time was most

         important. The relative use index is obtained by adding the

         number of birds seen during each scan for all observation periods

         (9 scans per observation period) for each season (spring, summer,

         fall) divided by the number of scans, divided by the total number

         of observation periods for a particular season (e.g. one bird

         seen during each of the 9 scans is the same as a flock of 9 birds

         observed for 1 scan - use index of 1.0).

              Several approaches of analyzing the data were undertaken.

         First, for most comparisons, the yearly data was broken down into

         three seasons of observation (spring, summer and fall). The

         species observed were separated into 4 guilds - waterfowl,



                                    10








        shorebirds, wading birds and gulls/terns (Table 1). An overall

        gross yearly comparison for each guild was initially reviewed.

        Because of the migratory nature of most of the species, and

        weather factors, particularly rainfall, seasonal use was judged

        to be most pertinent. Therefore, the ponds were compared to the

        controls in spring, summer and fall. Due to the variability of

        the controls, as described in the introduction, the control plots

        were separated into two distinct types - wet controls and dry

        controls.


             Two basic types of construction exist when designing and

        creating pond systems - manmade (new construction) and restored

        ponds (plugging previously drained tidal ponds). Where possible,

        restored ponds are incorporated in a system design and the

        effective utilization of these ponds compared to a new "ideal"

        pond was addressed. Within the manmade ponds, two construction

        techniques within two vegetation types were employed and assessed-

        closed systems and sill systems in salt hay habitat, and closed

        systems and sill systems within S. alterniflora habitat.


        Yearly Comparisons

             Overall yearly comparisons of the four guilds are presented

        in figures 4-7. Waterfowl usage in the ponds and controls showed

        parallel increases from 1987-90 with the ponds having a larger

        use index than the control areas (Figure 4). The use index in the

        ponds for 1987-89 were approximately twice the value as the

        controls while 1990 ponds were approximately 25% greater.

        Shorebird utilization demonstrated steady decreases from initial

        installation through 1990 for both ponds and controls. When


                                    11









         ponds are first constructed, expanses of thin spoil remains and

         is attractive to shorebirds for feeding on ipvertebrates. As the

         spoil areas revegetate, there is less habitat for the shorebirds

         and utilization becomes diminished as indicated in figure 5

         when the use index in 1987 was approximately 7.5 and diminished

         to approximately 2.0 in 1990. The control areas were similar in

         usage to the ponds for 1988-1990, whereas in 1987 the ponds were

         greater - 7.5 compared to 4.4. The use index of wading birds was

         generally low throughout the year with value of 2.5 or less.

         Between year comparisons of ponds and controls were similar for

         each year except 1989 when readings were 2.2 in the ponds and 0.2

         in the controls (Figure 6). Gull and tern usage ranged from 0.6 to

         1.8 in the ponds and 0-0.3 in the controls due to the lack of

         deep water in the control areas (Figure 7). The preceding data

         is a gross overall comparison of ponds and controls. The

         following data attempts to show distinct important differences

         and similarities among created ponds, natural and degraded

         marshes.



                        Seasonal Use of Ponds and Controls


         Waterfowl


              Waterfowl pond use indices were higher for each year in the

         spring with 1987 and 1988 twice the values as the control areas.

         Overall usage increased from 1987 with maximum utilization in

         1990 for both ponds (7.0) and controls (5.2) (Figure 8).

         Waterfowl use was greatest in the spring - black ducks in mid-

         February and March and green-winged teal in mid-April. Indices



                                    12









         in summer and fall fell considerably to below 0.7 in summer and

         below 1.4 in fall (.Figures 9 & 10). Although variable between

         years, the ponds were utilized more than control areas due to

         their capability of holding permanent water.



         Shorebirds


              Considerable use of the ponds and controls was realized in

         the spring of 1987 and 1988 with use indices of 6.6 and 8.2 in

         the ponds and 6.7 and 7.1 in the controls (Figure 11).    Marked

         decreases for both areas occurred in 1989 and 1990 to a   low of


         1.8 for both ponds and controls. This reduction is due    in part

         to vegetation recovery around the ponds perimeter which   reduces

         available feeding habitat. One pond whose vegetation recovery

         was only 50%, shorebird usage was higher than ponds of 90-100%

         recovery. During the wet period of the year the ponds and

         controls were almost identical in usage. Major species include

         willet, greater and lesser yellowlegs and peep species.

         Shorebird use in ponds was very high in the summer of 1987 with a

         use index of 10.7 as compared to 4.6 for the controls (Figure

         12). After 1987, the pond use index dropped to between 3.0-4.3

         whereas the controls declined to 1.2 by 1990. During the fall

         season shorebird use was reduced for both ponds and controls.

         Again the ponds in 1987 had over twice use index as the controls

         with remaining years similar (Figure 13). As previously stated,

         fresh spoil from new pond construction creates feeding habitat

         for shorebirds. The control plots were often similar in

         utilization during the three seasons. However, the utilization

         of the control areas are subject to adequate rainfall or flooding


                                     13









        tidal events whereas the ponds are permanent water habitat. Many

        times, particularly during mid to late summer certain control

        area pans would evaporate.


        Wading Birds

             Wading bird activity was minimal in spring for all years

        with a use index of less than 1.4 for ponds and controls (Figure

        14). During the summer, activity increased slightly during 1987,

        1989-90 within the ponds, while during 1988, the use index

        reached a high of 7.9. The controls were low for all four years

        with an index of 0.2-0.6 (Figure 15). The fall period was again

        low utilization similar to the spring with a use index of 0.4-

        1.2. The control areas reached 2.8 in 1988 while remaining years

        were 0.04-0.2 (Figure 16). Wading birds need water habitat deep

        enough and of a long duration to sustain fish population which

        the ponds provide year-round. Ten species of wading birds were

        observed with the major species being snowy and great egrets and

        great blue herons.



        Gulls and Terns


             Gull and tern activity was very low during spring and fall

        with a use index of less than 0.2 (Figures 17 and 19). The

        summer, however, had a peak use in 1987 of 3.9 and 2.8 in 1990

        (Figure 18). The major utilization during the summer were gulls

        resting on exposed spoil areas. The control areas had only two
 A      periods of use during all seasons for all years - spring and fall

        of 1987. The largest use index was 0.05.




                                    14








        Wet and Dry Control Compa:

             Due to the differences in the physical characteristics of

        the controls area and subjective observations in the field, the

        controls were separated into two categories - wet and dry

        controls. The wet controls contain flat pan areas capable of

        holding water after a tidal flooding event or rain and small

        tidal ponds. The dry controls are natural marsh areas of salt

        hay and S. alterniflora containing little or no water habitat.



        Waterfowl

             Springtime was the most utilized period of the year for all

        areas concerned as seen in figures 20-22. The ponds and wet

        controls were similar except in 1987 when the use index in the

        ponds was almost 5 times greater than the wet controls. The use

        index was as high at 7.0 in the ponds and 8.7 in the wet control

        by 1990 (Figure 20). An obvious but drastic difference was in

        the dry control when the use index was 0.13 or less for all

        years. Waterfowl utilization was considerably reduced during the

        summer and fall for all years (Figures 21 and 22) with indices of

        less than 0.7 in the summer and less than 1.3 in the fall. In

        each case the ponds were greater than the controls. The dry

        control areas had no waterfowl use during the summer and fall for

        all years.



        Shorebirds


             Spring shorebird utilization had similar use index patterns

        in 1987-90 with 1988 the peak year of usage for both ponds and

        wet controls. In every year the wet controls had larger use



                                    15








        indices then the ponds ranging from 31-45% above the ponds

        indicating a preference for the shallower, temporary pans (Figure

        23). As indicated by the declining trend towards 1990, the ponds

        perimeter vegetation caused a loss of ideal shorebird habitat but

        restoration of the ponds original condition is obtained. The

        fact that the wet controls followed the ponds similar yearly

        pattern may indicate an attraction to the Great Marsh ponds, and

        once they become vegetated usage becomes stable but less than

        newly exposed spoil. The dry controls had very little

        utilization during all years due to the lack of suitable habitat

        with indices of 0.75 or less for 1987-90.


             The summer use indices were highest in 1987 for the ponds

        and wet controls with a pond index of 10.7 and 7.5 for the wet

        controls (Figure 24). The use index for 1988-90 dropped to a

        stable, but lower 4.3, 3.0, and 4.1 for the ponds while the wet

        controls had a more gradual but similar decline of 6.8, 3.1 and

        2.0. The dry control areas were used even less in the summer

        with indices of 0.4 and 0.3 in 1987-88 and 0.0 in 1989-90 (Figure

        24).

             Fall utilization was considerably reduced for all areas

        concerned in 1987-90. The largest index was 3.1 in the ponds in

        1987 (Figure 25). The remaining comparisons were similarly low

        for the remaining years in ponds and wet controls. Only 1988 had

        any usage however meager (0.09) in the dry controls (Figure 25).

A       Wading Birds

             Spring wading bird activity was minimal in the ponds and

        controls for all years with the highest use index of 2.1 in the


                                    16



 'A









        wet controls in.1990 (Figure 26). The remaining indices were 1.3

        or less. Two years, 1988 and  1990, recorded 0.0 in the dry

        controls.


             Wading birds showed a preference for the ponds during the

        summer for all years (Figure 27). In particular, 1989 had the

        largest index of 7.0. In 1987, 1988 and 1990, the index was

        similar ranging from 1.6-2.2. The wet control areas use index

        ranged from 0.2-0.9 probably caused by loss of water habitat for

        fish survival. The dry controls were similar but slightly lower

        than wet controls ranging from 0.3-0.6. The fall period indices

        for the ponds were similar but variable between years ranging

        from 0.4-1.2 (Figure 28). The wet controls were slightly lower

        except for 1988 when the use index reached 4.7 followed by 0.0 in

        1989. In 1987 and 1990 the dry controls were lower, recording

        0.0 in 1987 and 1990, while 1988 and 1989 were 0.06 and 0.09.

             Gull and tern activity was most prevalent in the summer in

        the ponds for all years with 1987 and 1990 the largest indices of

        3.9 and 2.8 (Figure 29). The wet controls in 1987 and 1988 had

        very low indices of 0.01 and 0.04 while the dry controls had no

        recorded utilization for all years.



        Manmade and Restored Ponds


             Manmade and restored ponds are the two basic options for

        pond construction when designing OMWM systems. Manmade ponds are

        shallow (up to 18") with tapered sides. Many species of

        waterfowl, wading birds and shorebirds are able to utilize these

        shallow depths. Restored ponds were once non-tidal but grid-



                                   17








        ditching converted them to tidal ponds. They are generally

        deeper probably due to scouring, and the two ponds surveyed did

        not contain widgeon grass. However, they provide valuable

        permanent water habitat attractive to waterfowl, including bay

        species such as bufflehead and mergansers, wading birds and long-

        legged shorbirds. The following series of figures (30-39)

        illustrate comparisons between these two methods of construction.

             The man-made pond indices during spring were variable

        between years with 1990 recording the largest index of 7.2

        (Figure 30). Restored pond indices were low in 1987 and 1988

        (1.0 and 1.2) however 1989 restored pond use index exceeded the

        manmade pond index 5.7 to 1.6 while 1990 was similar. During the

        summer, use indices fell to 0.7 or lower for both manmade and

        restored ponds for all years (Figure 31). In 1989 and 1990

        restored use indices were 0.0. Manmade pond indices were again

        low in the fall having a maximum in 1989 of 1.6. The restored

        pond only had one year, 1987, with any utilization which was

        twice as high, 3.2, as the manmade pond (Figure 32).

             During the spring shorebird period, utilization of the ponds

        was extreme in the manmade ponds during 1987 and 1988 with use

        indices of 6.9 and 9.2 (Figure 33). As previously stated, as the

        pond perimeter revegetates shorebird use habitat and usage

        diminishes as was the case in 1989 and 1990 when indices were


        reduced to 3.4 and 1.7 respectively. The restored ponds followed

        similar patterns with each year lower except for 1990 when values

        were similar, than manmade ponds with a maximum index of 5.1. A

        similar pattern for the summer was observed in the manmade ponds.



                                   18








        After a high index of 12.8 in 1987, shorebird utilization fell to

        between 3.4 and 5.0 in 1988-90 (Figure 34). The restored ponds

        were low in 1987, 1988 and 1990 with indices of 0.1-1.1 while

        1988 had the highest index of 2.6. The fall period again

        demonstrated a declining trend towards 1990 in the manmade ponds

        from an index of 3.8 in 1987 to 0.2 in 1990 (Figure 35). The

        restored pond indices were low in 1987-89 considerably less than

        manmade ponds, ranging from 0.0-0.2 followed by 1.8 in 1990.

             Wading bird activity during the spring was generally low

        during all years in manmade and restored ponds. The peak index

        for manmade ponds was 1.6 in 1988 and 1.7 in 1989 in restored

        ponds (Figure 36). The major difference between years was in

        1988 when manmade ponds exceeded the restored ponds 1.6 to 0.03.

        The summer period had marked increased utilization in the manmade

        ponds while a slight increase was observed in the restored ponds.

        In 1987, indices for both manmade and restored ponds were

        similar, however the manmade ponds exceeded the restored ponds in

        1988-1990 with a peak index in 1989 of 8.4 whereas the peak in

        restored ponds was 1.5 in 1987 (Figure 37). The fall indices

        between years were similarly low in both manmade and restored

        ponds with a maximum index less than 1.4 (Figure 38). During

        1990 the restored ponds recorded 0.0 usage while the manmade pond

        index was 0.8 noting the biggest difference during fall.

             As indicated in previous text and graphs the majority of

        gull and term activity occurs during the summer. Spring and fall

        utilization was below 0.25 for all years. Gulls and terns showed

        a definite preference for the manmade ponds during all years. A



                                   19








        majority of this usage were gulls using the spoil and mudflat

        areas as resting zones. 1987-and 1990 were peak years with use

        indices of 4.8 and 3.5 (Figure 39).



















































                                   20












                                   L 11
                      GRE.AT MARSH WATERFOWL
                                                    1987            1990


                    USE INDEX
                   5



                   4-



                   3



                   2







                   0
                                      PONDS                                     CONTROLS


                                    = 1987         M 1988         M 1989               1990

                     Figure 4. Yearly Waterfowl Indices for Ponds and Controls



                             kL


                       GREAT MARSH SHOREBIRDS
                                                    1987            1990


                     USE INDEX
                   8




                   6




                   4








                                                                   . ............
                   2


                                           .......... ......

                                               .. .. ......


                                                                                         .. .... ...... .....
                                             ......... . .

                                                                                           .......... .
                   0
                                      PONDS                                     CONTROLS


                                          1987     M 1988         EM 1989              1990
                                                                     1@i









                    Figure 5. Yearly Shorebird Indices for Ponds and Controls





                   GREAT MARSH WADING BIRDS
                                                     1987            1990


                      USE INDEX
                   2.5



                     2



                    1.5









                                              ............
                                              ............
                                               ...............-
                                               ..........I...-
                                            ..............  ...........
                                             ......  .........
                                                  ...........
                                                  ..........
                                             .. .......................
                   0.5


                                                 ............-
                                               ....... ........

                                             ..........  ..........
                                                     .......                            ....
                                            ...... ......... . ....
                                                  ..........
                     0
                                        PONDS                                    CONTROLS
                                                     9                                         11



                                           1987      M 1988        EM1989               1990

                       Figure 6. Yearly Wading Bird Indices for Ponds and Controls





                     GREAT MARSH GULLS/TERNS
                                                     1987            1990


                      USE INDEX
                     2




                   1.5









                   0.5                                          . ..... ......                 .............




                     0
                                        PONDS                                   CONTROLS


                                     = 1987        M 1988          EM 1989        = 199o

                      Figure 7. Yearly Gulls and Terns Indices for Ponds and Controls



               hh,    I      L            i@                  I     I   I  1@



                      GREAT @AARSH VVATERFO'VVL
                                                        SPRING


                    USE INDEX
                  8


                  7                                            . ... ..


                  6


                  5


                  4


                  3


                                            ... . ... ....
                  2



                                                                                          ............ .
                                                                                          ......... ..


                                                                                             ...........
                                           ..........-.... .....                       ....
                                           ...... ... . ........
                                           .. .. .. ......

                                                                                          ..................
                  0
                                      PONDS                                     CONTROLS



                                          1987          1988            1989           1990

                    Figure 8. Waterfowl Use Indices in Spring 1987-90 for Ponds and Controls



               L


                       GREAT MARSH WATERFOWL
                                                        SUMMER


                       USE INDEX
                  0.7 -


                  0.6-


                  0.5-


                  0.4-                                                                                   ...........


                  0.3-                                                                                   . .. ...


                  0.2-


                                              ...........
                  0.1


                    0--
                                        PONDS                                    CONTROLS
                                                                      @L



                                           1987     M 1988         EM 1989        = 1990

                        Figure 9. Waterfowl Use Indices in Summer 1987-90 for Ponds and Controls





                        GREAT MARSH WATERFOWL
                                                             FALL


                        USE INDEX
                    1.4


                    1.2 -





                    0.8


                    0.6-


                                                 . . .. .......
                                             ..... .....
                    0.4


                                             .. .... . .... .


                    0.2


                      0-
                                         PONDS                                    CONTROLS


                                            1987           1988          1989      EM 1990

                       Figure 10. Waterfowl Use Indices in Fall 1987-90 for Ponds and Controls





                        GREAT MARSH SHOREBIRDS
                                                          SPRING


                      USE INDEX
                    10



                    8



                    6-



                    4


                                                                                           . ..........-
                                                                                             .............

                                                                                              ............
                                                                                        ...........


                                                                                        .......... .......  ......
                                                         . ......... .. . ..... ...... .... . .......... .......... .. ............
                                              .............                             ........... ... ............. .... ...........
                    2




                                        PONDS                                    CONTROLS


                                     = 1987               1988           1989     = 1990

                      Figure 11. Shorebird Use Indices in Spring 1987-90 for Ponds and Controls





                        GREAT MARSH SHOREBIRDS
                                                        SUMMER


                      USE INDEX
                    12


                   10-                                                         . . .....         ... ....... .


                    8                                                                            . ...... ..


                    6



                    4-


                    2



                                                                                        ...... ....

                                             ......... ..... ....                       ....
                                                 ...............
                    0
                                        PON DS                                   CONTROLS


                                     = 1987               1988           1989     ME 1990

                      Figure 12. Shorebird Use Indices in Sumner  1997-90 for Ponds and Controls





                        GRE AT @AARSH SHOREBIRDS
                                                            FALL


                      USE INDEX
                   3.5


                     3 -


                   2.5


                     2


                   1.5





                   0.5 -

                                                                                           ................
                                                                                             ..........
                                                                                            ...............
                                                ..... ....                              . .......... ...........
                                                                                             ..........
                                                   ......                               . .... ---,  ........
                                                    ....                                 ........ . ... .......
                                                                                             .............
                                                ...........-                                . ...... .
                                              . ....................
                     0                        ZZZ@-- -'                                         L-
                                        PONDS                                    CONTROLS


                                     M 1987              1988            1989     M 1990

                       Figure 13. Shorebird Use Indices in Fall 1987-90 for Ponds and Controls



         illm = = = = = = = = = m = m m m m = m


                    GREAT MARSH WADING BIRDS
                                                         SPRING


                       USE INDEX
                   1.4




                                                                                             . .... ... .. . ..... .-
                   1.2




                                                                                           .. . ... .. ..-



                   0.8                                                          .... . . ... .



                                                                                                         ............
                   0.6




                                                        .. .. ...... .. ...... ......... .                ...........
                   0.4



                                             .....                                        ....... .....
                                                                                   ..............
                   0.2


                                                                                            ............ ..
                      0
                                        PONDS                                    CONTROLS


                                     = 1987         M 1988         EM 1989        = 1990

                       Figure 14. Wading Bird Use Indices in Spring 1987-90 for Ponds and Controls





                  GREAT MARSH WADING BIRDS
                                                       SUMMER


                    USE INDEX
                  8


                  7                                                                              .... .. . .. . ....

                                             ..... .....

                                                                                . . . ...... .       . .... .
                  6
                                              .. .. ... ... ..







                  4



                                                                               .. . ... . .... .......... .... .
                  3
                                             ...........



                                                              ............. .- -            ..............
                  2



                                       . .. ............
                                       . ............
                                                                                    . . ..........    . . ....
                                           .......... .........-...
                                               ..........
                                           ..............-... .....
                                           .... ...... ........

                                             .............
                                              ... ........


                                       PONDS                                    CONTROLS


                                    = 1987         M 1988         M 1989         = 1990

                     Figure 15. Wading Bird Use Indices in Summer 1987-90 for Ponds and Controls





                    GREAT MARSH WADING BIRDS
                                                             FALL


                       USE INDEX
                      3


                    2.5


                      2                                                   . ..........                  .. .......... ... .



                    1.5                                                                      . .......






                    0.5                                                                             . .....



                                             ........ ....
                                             ...............
                      0                       ........ .1
                                        PONDS                                    CONTROLS


                                     = 1987               1988           1989     EM 1990

                       Figure 16. Wading Bird Use  Indices in Fall 1987-90 for Ponds and Controls





                      GREAT MARSH GULLS/TERNS
                                                          SPRING


                        USE INDEX
                  0.16


                  0.14 -


                  0.12 -


                    0.1 -

                  0.08 -


                  0.06 -                                                                                 .. ....... ..




                  0.02                                                ....      ........                  . .....


                      0
                                         PONDS                                   CONTROLS


                                     = 1987               1988      IM 1989        ME 1990

                        Figure 17. Gull and Tern Use Indices in Spring 1987-90 for Ponds and Controls





                    GREAT MARSH GULLS/TERNS
                                                       SUMMER


                    USE INDEX
                   5



                   4



                   3                                                                        .............. . .-



                   2                                                                                       . . .......




                                                                ... ............. .... ........... ..... . . ...






                                              ..................
                   0
                                      PONDS                                     CONTROLS


                                    = 1987               1988           1989     = 1990

                     Figure 18. Gull and Tern Use Indices in Summer 1987-90 for Ponds and Controls





                      GREAT @AARSH GULLS/TERNS
                                                             FALL


                        USE INDEX
                     0.2




                   0.15                                                                             ... ........-




                    0. I                                                                        ..... ...... ......... .




                   0.05                                               . .. . ..... ............. .......




                       0
                                         PONDS                                   CONTROLS


                                     M 1987               1988     IM 1989         M 1990

                        Figure 19. Gull and Tern Use Indices in Fall 1987-90 for Ponds and Controls



             mm = = = m = mm mm = m = M =I


              GREAT MARSTH, WATERFOWL
                                  SPRING


             USE INDEX
            10



            8



            6 -



            4-



            2                                 .... ..... . .
                      ....... .......
                      ............ ... .... . ..
                      ..........  ...  ........ .......
                      ........ ....    ...
                                       ..........
                                       .......... ......
                                        ............
                        ........       ......

                       ................
                      ...........
            0
                   PONDS         WET CONTROLS     DRY CONTROLS
                                    km




                         1987     1988     1989     1990

              Figure 20. Waterfowl Use Indices in Spring 1987-90 for Ponds, Wet & Dry Controls



  1111MI              = M = = = = = = M M M = = M = M



                       GRE AT MARSH WATERFOWL
                                                        SUMMER


                       USE INDEX
                  0.7


                  0.6-


                  0.5  . . .. .. . ...... . ...


                  0.4-                                                                                 .... ... .. ......... . .... .


                  0.3 -


                  0.2 -                           . .. ...                   ...... .....

                                      .............
                                       ................
                                       .................
                                        ............
                                         ..........
                  0.1  . ...........   ................
                                     ..........  ......
                                        ............
                                       ...............
                                     ...............
                                      . ..........
                                     ..........
                                         ..........
                                        ............
                                       .................
                                      ..................


                    0
                                 PONDS                  WET CONTROLS                 DRY CONTROLS


                                     = 1987         M 1988         EM 1989        = 19go

                       Figure 21. Waterfowl Use Indices in Summer 1987-90 for Ponds, Wet & Dry Controls





                       GRE.AT MARSH WATERFOWL
                                                            FALL


                      USE INDEX
                   1.4


                   1.2






                                      ...........



                   0.8



                                      ...............
                   0.6-


                   0.4               ....


                                      ................
                                      . .........
                                      ................
                                       ...............
                                        ...........
                                     .. . ........
                   0.2                                       ...... ....-...... ..... ............ ........ .... . ........ . .. ........ . ............ ............ ...... ...................... ............. .. ...........
                                      ...... .......
                                        ..........

                                     ...........
                     0
                                 PON
                                      DS                WET CONTROLS                 DRY CONTROLS


                                     = 1987         M 1988         IM 1989        ME 1990

                        Figure 22. Waterfowl Use Indices in Fall 1987-90 for Ponds, Wet & Dry Controls





                        GREAT MARSH SHOREBIRDS
                                                         SPRING


                      USE INDEX
                   14


                  12-


                   10-.                                                                         ..... ......... ..........


                    8                                               .... . ..... ..... ......


                    6                  ........ . . . .                  .. ... .... ..



                                            .... ......                             .. ... .. ......... ... . .......... . . ......-.............. . ....... .. .... . ........ .

                                                                  .................
                                                                  .................
                                                                    .............
                                                                    ..............


                                       ...........
                                     ..............
                                             ................ ... ........                . . ...... ... .... ..... ..... ............
                    2                .........
                                                                  ...........  ......
                                                                  ...................
                                     ..........                   ........  .........

                                     ..........

                                                                     ..........
                                       ...........
                    0
                                PONDS                  WET CONTROLS                  DRY CONTROLS
                      @1                                               IN

                                    = 1987               1988           1989           1990

                       Figure 23. Shorebird Use Indices in Spring 1987-90 for Ponds, Wet & Dry Controls





                        GREAT MARSH SHOREBIRDS
                                                        SUMMER

                      USE INDEX
                    12


                   10 -


                    8



                    6                                                  . . .....



                    4-




                                         .......                     ......
                    2
                                                                                          ...... .....



                                      ....... ....                ....-...
                                        ...........               ....


                    0
                                PONDS                   WET CONTROLS                 DRY CONTROLS


                                          1987           1988      EM 1989        ME 19go

                      Figure 24. Shorebird Use Indices in Summer 1987-90 for Ponds, Wet & Dry Controls





                        GRE AT @AARSH SHOREBIRDS
                                                             FALL


                      USE INDEX
                   3.5


                     3                                                 ... .... ....


                   2.5                                                                       .. . .. .. ........ ...


                     2


                    1.5                                                                      . . ....






                                                                  ................
                                                                  ... .1, ...........
                                                                  ...........

                                             ..............
                   0.5
                                                                   ..............
                                                                    ..........


                                                                  ................
                                                                    ............
                     0
                                PONDS                   WET CONTROLS                 DRY CONTROLS


                                     M 1987         M 1988         M 1989         M 1990


                   Figure 25. Shorebird Use Indices in Fall 1987-90 for Ponds, Wet & Dry Controls





                   GREAT MARSH WADING BIRDS
                                                         SPRING


                      USE INDEX
                  2.5



                     2



                  1.5










                                      ............


                                       .. .........
                                      .. ..... .....

                                                                   .......................   .................... .... .. ...........
                  0.5                 .... .. .
                                      ..........
                                     ............



                                       ...........
                     0
                                 PON DS                 WET CONTROLS                 DRY CONTROLS



                                          1987           1988            1989           1990


                  Figure 26. Wading Bird Use Indices in Spring 1987-90 for Ponds, Wet & Dry Controls





                           GREAT MARSH WADING BIRDS
                                                                                SUMMER


                               USE INDEX
                           8



                               . . .. .. ......                                                                 ...... ... .. ... ... . ...... .. ..... ......
                           7
                                                      . .. ........
                                                      ...... ....


                                                      ..........
                                                      ....... ......
                                                      ............
                               . . . ..... ..... ... .......... .......                                                               .. .... .............. . . ..... ............
                           6
                                                      ...... .. .......



                                   ..... .. .. .. . ...
                                                                                                                                     . ... . ..... .. ... .......-. .. .... .




                                                                                                                                        ... ... ..........
                           4



                                  .... ....... . ... . .....
                           3

                                                      . . . . . . . . . .
                                                      . . . . . . . . . . . . . .

                                                      . . .. . . . . . . .
                                                      ... ..........
                                                      . . . . . . . . . . . . .
                                                      . . .. . . . . . . . . .
                                     ......... .......... .. .. ....... ...        . .. ... ..... .... . ..........             . ....... ............... ............ .. ...........
                           2                             . . . . . .

                                                       . . . . . .. . . .
                                                      . . . . . . . . . .
                                                       . . . . . . . . . . .

                                                                                                 . . ................. ....... ... ........... ............... ... ....... .. ....... .. . .................... ... ......


                                                      . . . . . . . . . . . .


                                                          . . . .                                 . . . . .                                     . . .
                           0
                                              PONDS                             WET CONTROLS                                DRY CONTROLS
                               Lv i

                                                             1987         M        1988         EM       1989                  1990


                           Figure 27. Wading Bird Use Indices in Summer 1987-90 for Ponds, Wet & Dry Controls



                                   L iL                @



                  GREAT MARSH WADING BIRDS
                                                           FALL


                    USE INDEX








                  3                                                                             . .....   .. ........



                  2






                                       ............       . .. ...    . .. ...       .. .... . . ...






                  0.
                               PONDS                   WET CONTROLS                  DRY CONTROLS


                                    = 1987         M 1988 M 1989                 = 1990


                  Figure 28. Wading Bird Use Indices in Fall 1987-90 for Ponds, Wet & Dry Controls





                    GREAT MARSH GULLS/TERNS
                                 A Ll
                                                       SUMMER


                     USE INDEX
                   5



                   4



                   3                                                                        ...... .....



                   2






                                                                                      . .........-. .. ....-






                   0
                               PONDS                   WET CONTROLS                  DRY CONTROLS


                                    = 1987         9M 1988        MI 1989        = 1990

                   Figure 29. Gull and Tern Use Indices in Summer 1987-90 for Ponds, Wet & Dry Controls





                                 GREAT MARSH WATERFOWL
                                                                                  SPRING


                              USE INDEX
                           8




                           6                                                                          ....... .... . .. .                                  ...... ....


                                                                                                                                          ....... ....
                                                                                                                                          . ... . ... .........
                                                                                                                                          ...............
                                                                                                                                          ..........
                                                                                                                                          ..........

                                                                                                                                          . .. ...........
                                                                                                                                          .. ... .. .... ..

                                                                                                                                          ..............
                                                                                                                                          .......................
                                                                                                                       . . . .... ........ . . ...........
                                                                                                                                          .............
                                                                                                                                          .. ..........
                                                                                                                                          ............
                                                                                                                                          ........ ......-
                                                                                                                                          ...... . . . .........

                                                                                                                                          ...........
                                                                                                                                          ...... ........
                                                                                                                                          ..... .... ...........
                                                                                                                                          1-11.1, ..........
                                                                                                                                          .... ..............
                                                                                                                                          .1-1.1 ...................
                                                                                                                                          .................
                                                                                                                                          . ..............

                                                                                                                                          .............
                                                                                                                                          ....................
                                                                                                                                          .............. ....... ....
                                                                                                                                          ..........
                                                                                                                                          ..........

                                                                                                                                          ..........
                                                                                                                                          ....................-
                                                                                                                                          ..........
                                                                                                                                          ..........................
                                                                                                                                          -... ...............
                                                                                                                                          .................. ........
                                                                                                                                          .. .... ... .
                                                                                                                                          ...........
                                                                                                                                          .............
                                                                                                                                          .. ...........
                                                                                                                                          ...........
                                                                                                                                          ........ ....
                                                                                                                                          ..................
                                                                                                                                          ............... ..........
                                                                                                                                          ............. .......
                                                                                                                                          ................
                                                                                                                                          ... ................
                                                                                                                                          .............. .......
                                                                                                                                          ............
                                                                                                                                          ............ ......

                                                                 ... ..  ......

                                                                    ...........
                                                                    ..........


                           0
                                                    MANMADE                                                            RESTORED


                                                    = 1987                ME 1988               EM 1989                                   19go


                     MANMADE AND RESTORED PONDS

                           Figure 30. Waterfowl Use Indices in Spring 1987-90 for Manmade and Restored Ponds





                        GREAT I\AARSH VVATERFOVVL
                                                        SUMMER


                       USE INDEX
                   0.8




                   0.6 . .... . ......                                                            .. . . . . ..... ...




                   0.4 -                                                                        . .... .




                   0.2


                                                  ...........
                                                 ..... .... .
                                             ............

                                             .................
                                               .............
                                             ...........
                                               ............
                                             ............
                                             ............



                      0
                                     MANMADE                                      RESTORED


                                     = 1987         OM 1988        EM 1989              1990


               MANMADE AND RESTORED PONDS

                   Figure 31. Waterfowl Use Indices in Summer 1987-90 for Manmade and Restored Ponds





                       GREAT MARSH WATERFOWL
                                                            FALL


                      USE INDEX
                   3.5


                     3


                   2.5


                     2


                   1.5









                                                                  .. ........-
                   0.5



                                               .. . ..........
                    0--                      .. ....
                                     MANMADE                                     RESTORED


                                     = 1987         BE 1988        EM 1989        IM 1990


              MANMADE AND RESTORED PONDS

                   Figure 32. Waterfowl Use Indices in Fall 1987-90 for Manmade and Restored Ponds





                        GREAT MARSH SHOREBIRDS
                                                         SPRING


                      USE INDEX
                    10



                    8



                    6



                    4-



                                              ............
                                             ........... .... ... ...
                                             .......................
                                             .......................


                                                                 .....................
                    2                        ......... ..
                                             .... ................ ...





                    0
                                     MANMADE                                      RESTORED


                                          1987      EM 1988              1989     IM 1990


               MANMADE AND RESTORED PONDS

                   Figure 33. Shorebird Use Indices in Spring 1987-90 for Manmade and Restored Ponds





                        GREAT MARSH SHOREBIRDS
                                                        SUMMER


                      USE INDEX
                    14


                   12 -                                                                            . .......


                   10-                  ...... ....


                    8


                    6                                                                                ..... ..... ......


                    4-                         . .......-        . .... .. ..

                                            ....... ........ ........
                                               ..........


                                                                        ..........        . . .... ....... . ..... .......-..........
                    2
                                               ..............


                                                  ..........
                                             .....................
                                                                                             .............

                                             ..............
                    0--
                                     MANMADE                                     RESTORED


                                           1987     EM 1988              1989     IM 1990


               MANMADE AND RESTORED PONDS


                   Figure 34. Shorebird Use Indices in Summer 1987-90 for Manmade and Restored Ponds





                       GREAT MARSH SHOREBIRDS
                                   X-11
                                                           FALL


                     USE INDEX
                   4




                   3                  .... .......                         . ... ..      . . ... ............




                   2                                                                                      . .. ..... .. .........






                                                                       ............      ..............








                   0
                                    MANMADE                                      RESTORED


                                    = 1987               1988           1989     IM 1990


               MANMADE AND RESTORED PONDS

                   Figure 35. Shorebird Use Indices in Fall 1987-90 for Manmade Restored Ponds





                             GREAT MARSH WADING BIRDS
                                                                                    SPRING


                                 USE INDEX
                               2




                                                                                                                                  ...................
                                                                                                                                    ......... ..
                                                                                                                                    . .........
                                                                                                                                    .... .. ..........
                                                                                                                                    .. ....... .....
                                                                                                                                            .............. ...
                                                                                                                                            ...............
                                                                                                                                    ....... ....
                           1. 5      ........ ...... .. ..... .. . .                                                             ...........
                                                                                                                                            .. .........
                                                                                                                                    .. ..........

                                                                                                                                            . ..........
                                                                                                                                            ...........
                                                                                                                                            ................
                                                                                                                                            I.......... ...
                                                                                                                                            . ..............
                                                                                                                                    ..... ..... .
                                                                                                                                  . ..... ..... .... ..


                                                                                                                                 ... ... ............ .
                                                                                                                                  .. . ......... .. ... .
                                                                                                                                 . ............ .
                                                                                                                                            . ..... ..... ..
                                                                                                                                 ......... ...







                                                                                                                                    ........ ..
                                                                                                                                 . .......... ... ... ....
                                                                                                                                  . .............
                            0.5  . ..... .......... ..... .............                                                          .. .....   ...... ......
                                                                                                                                            .... ........



                                                                  ............ .........
                                                                                                                                 ............
                                                                                                                                            .. .........
                                                                   ..... ...........
                                                                                                                                            ....... . . . . .
                                                                                                                                 .... .........


                                                                 ...... .... .. .. ...
                               0                                                                                                    ..............
                                                      MANMADE                                                           RESTORED
                                                                        im



                                                              1987          ME 1988               EM1989                IM 1990


                     MANMADE AND RESTORED PONDS


                            Figure 36. Wading Bird Use Indices in Spring 1987-90 for Manmade and Restored Ponds



         611M M M M M M M M M M M M @ @ @ @@



                   GREAT MARSH WADING BIRDS
                                                        SUMMER


                      USE INDEX
                    10





                                               .......... .........
                    8                         ......  .......
                                              ..... ...... . .






                                                                                          .......... ... .......
                    6-



                                             ...... ......... .. ....

                                               . ........ . .



                                               ..... .. . .. .






                                                                             ...........
                    2                         .......
                                                 ...... ......
                                             ..................
                                              ...... . ..... .......


                                             . ...............


                                             .................
                                             .......... ....
                                             . .........
                    0
                                     MANMADE                                     RESTORED
                      AMEN 0                                          M

                                     = 1987         MM 1988        EM 1989        10 19go


              MANMADE AND RESTORED PONDS


                   Figure 37. Wading Bird Use Indices in Summer 1987-90 for Manmade and Restored Ponds





                             GREAT @AARSH VVADING BIRDS
                                                                                        FALL


                                 USE INDEX
                            1.6


                            1.4 -


                            1.2 -            .. . .... .. ..



                                                                                                             ...... .......-



                            0.8 -                                                                                                                          . . ....-


                            0.6 -                                                                        . ... ....


                                                                          ............
                                                                          ..........
                                                                          ...... ....
                                                                                                   ... .. ......
                            0.4
                                                                  ...... ... ..... .........
                                                                  ........ ......
                                                                  .............
                                                                  ...... ........ .......
                                                                  ........ ... . ...... .
                                                                  ............
                                                                  ................ .......
                                                                          ...... .......
                                                                  .................
                            0.2 -                                                                                                                     . ... ..-
                                                                  ..............
                                                                    .............
                                                                  ............
                                                                  -. .............
                                                                  ............
                                                                  ............ ......
                                                                  .............. ...........
                                                                   . .. .............
                                                                          .......... .......
                                                                  .................
                                                                    .................
                                                                  ........... .......  ...
                                                                  .............
                                                                  ..........
                              0
                                                       MANMADE                                                        RESTORED


                                                     M 1987                ME 1988               IM 1989               ME 1990


                     MANMADE AND RESTORED PONDS

                            Figure 38. Wading Bird Use Indices in Fall 1987-90 for Manmade and Restored Ponds





                    GREAT MARSH GULLS/TERNS
                                                      SUMMER


                    USE INDEX
                  5



                  4-               .......... ............... .-.. ........           .................... ......... ............... .



                  3                                                                    ............. . . ....... 1----.1-1-1-1 ............-



                  2                  .... ......... . .. .. ...         . ... ... . . ... .. ... .. ...



                  I                 ................................... .. .......... ........ .... ........ .. ............. ..........-...........



                  0
                                   MANMADE                                      RESTORED


                                   = 1987               1988           1989            1990


              MANMADE AND RESTORED PONDS

                   Figure 39. Gull and Tern Use Indices in Summer 1987-90 for Manmade and Restored Ponds









                                  WATER QUALITY
             Water'quality data was collected from the 12 ponds during

        1987-1990. Parameters sampled include: salinity, dissolved

        oxygen, pH, specific conductivity, carbon dioxide, ammonia,

        hardness, chloride, sodium, nitrate, nitrite, and ortho-

        phosphate (Fig. 40). Initially, the lab analysis was conducted by

        personnel at Delaware State College. However, as funds were

        reduced, these tests were completed using Hach test kits and

        meters.



        Salinity

             Salinity within the estuary is highly variable. The

        important factor in species composition, distribution and

        maintenance is the magnitude of seasonal and tidal fluctuations

        in salinity. The highest salinities occur during the summer due

        to lower rainfall and evaporation. Within the ponds salinities

        varied by as much as 18 ppt throughout the year with a range of

        4-33 (Table 2). The organisms that reside in these ponds are

        able to withstand these variations through osmoregulation. There

        was little difference in salinity between salt hay constructed

        ponds or S. alterniflora constructed ponds. Each was variable

        throughout the year.


        Dissolved Oxygen

             Dissolved oxygen within the ponds can have extreme

        variations on a daily basis. Depending on the amount of aquatic

        vegetation, DO levels can be saturated during the day, and fall

        to 1 ppm or less overnight. This also occurs in natural marsh



                                   57























































                 Figure 40. Water Sampling at Great Marsh








                                       58








        ponds. Fish species are forced to "gulp" air during the night.

        The summer months tended to have the lowest DO readings due to

        increased biological activity. Samples were collected during

        mid-morning and were within biologically acceptable levels except

        for "U"am instances during August when the DO fell below 2 PPM

        (Table 3). No fish kills or other organism die offs were

        observed.



        pH
             The pH\of the ponds remains fairly constant due in part to
        the usually monthly tidal inundation. Seawater is strongly

        buffered and remains a constant pH of 8-1 to 8-3 (Reid & Wood

        1976). As table 4 indicates, pH values ranged from 6.53 to 9.4

        with the majority of readings falling between 7.2 and 8.5.

        Voudoroff and Katy, 1950, state that the pH limit for the most

        resistant fish species is 4.0 to 10.1.



        Carbon dioxide


             Carbon dioxide is important in that it buffers the water

        against rapid changes in pH. C02 values for the ponds range from

        45.2 ppm to 170ppm with the highest readings occurring during the

        summer (Table 5). The warm summer temperatures cause the

        highest rate of respiration and maximum rate of decomposition.

        Voudoroff and Katy (1950) state that concentrations of 100-200

        PPm Of C02 can be lethal to sensitive fish in the presence of

        adequate dissolved oxygen.    Higher concentrations may be

        tolerated by hardier esturine organisms.





                                    59










         Ammonia


              Excessive ammonia levels are harmful to aquatic species

         because it decreases the ability of the hemoglobin to combine

         with oxygen and can cause suffocation (Brockway 1950). There is

         no distinctive differences of ammonia levels between ponds,

         Values range form 0-2.4 ppm (Table 6). Samples collected

         during summer months (June and August) tended to have higher

         concentrations. According to Ellis (1937) concentrations of 2.5

         ppm are considered harmful in the pH range of 7.4 - 8.5.



         Sodium/Chloride/Specific Conductivity/Hardness

              Specific conductivity is a measurement of the total ion

         concentration of water and is directly related to salinity. In

         seawater, sodium and chloride comprise the majority of the ions.

         In freshwater, calcium and magnesium make up the largest

         percentage. The brackish ponds average salinity is less than

         that of seawater so there is freshwater input. Tables 7, 8 and 9

         depict the values for sodium, chloride and specific conductivity.

         Hardness is primarily attributable to calcium and magnesium ions.

         All values in the ponds ranged from 71-479 ppm (Table 10).

         Berger (1943) states that "good" quality freshwaters should not

         exceed 270 ppm hardness. Brackish waters have higher total ion

         concentrations hence hardness values can be considerably higher.

         Samples taken at a river mouth adjacent to the Great Marsh had

         values as high as 6800 ppm (Delaware 1980 State Water Quality

         Inventory, July, 1980). The results of the sodium, chloride,

         specific conductivity and hardness samples taken are considered



                                    60








          normal values and not limiting to the biological health of the

          ponds.



          Nitrate/Nitrite

               Nitrate acts as a fertilizer for all types of plants.

          However, excessive nitrates can stimulate the growth of algae and

          aquatic weeds resulting in algae blooms. These blooms occur

          every year in varying degrees in all ponds from approximately 5%

          to 100% surface coverage. Nitrate values were generally higher

          in the spring and fall samples (Table 11).


               Nitrites are quickly converted to nitrates and are generally

          found in small amounts. Ponds were sampled with Hach nitrite

          kits. No nitrite values were high enough to register.


          Phosphate

               Phosphates rarely produce toxic effects upon fish and other

          aquatic life (Vivier, 1935; Abegg, 1950; Fuller, 1949), but may

          contribute to increased algae production. Values were variable

          between 0 and 2.7 ppm with most readings below 1.0 ppm (Table

          12). These values are similar than those recorded at the mouth

          of the Broadkill River near the Great Marsh in 1978-79 (Delaware

          State Water Quality Inventory, July 1980) which ranged from 0.25

          to 2.75 ppm.


               The ponds at Great Marsh are generally shallow in depth and

          provide a year round stable habitat designed to replace and

          improve the loss of permanent water habitat lost through grid

          ditching. The water quality parameters sampled pose no


                                       61




















                                                               FCND
                    EATE     -----1-----  2----- 3----- 4-----5-----6----- 7-----8----- 9 ---- 10 ---- 11 ---- 12

                    APR 1987     24     22    20     14    18    11     16    16     22     17    22    17

                    AM  1987     32     32    31     28    28    25     24    24     30     27    30    29

                    OCr 1987     18     16    11     12    14     7     18    16     24     20    22    13
     ON             WAR 1988     22     15    22     18    14     8     12    10     26     16    26    22
                    ALB 1988     31     31    30     19    21    21     26    21     31     25    27    29

                    RN  1989     18     16    24     10    12    10     10     9     33     14    20    14

                    AUG 1989     16     10    28     14     8     5       7    6     26     12    18    22

                    NAY 1990      -      4    23     10     8     6     10     9     25     16      -   17

                    AUS 1990      -     20    27     14    16    16     16    15     26      -      -   16








                    Table 2. Pond Salinities in all Ponds for 1987-90




















                                                              FCND

                                  1      2     3      4      5     6      7     8      9    10     11    12

                   EATE

                   APR 1987    8.1       8  9.5    8.7   8.1    8.6    9.4   8.8    8.2   8.3    6.7   9.2
                   AUG  1987   6.2    6.4      5   4.1       5  6.8    6.9   8.7    8.3   7.1    6.5   2.3
                   OCr  1987   8.8    8.2   9.2    9.2   8.9    8.8    9.2   8.9    9.1   9.2    8.8      9
                   MR   1988   8.4    8.5      8   7.8   8.2    8.6    8.4   8.2    8.8   8.4    7.7   8.5
                   AUG  1988   5.6    6.1   6.2    6.5   6.6    6.6    5.2   5.7       6     6   6.2       1
                   RN   1989      8   5.7   9.5    6.5   10.5   4.4       5  5.2    5.2   7.1    6.2     10
                   ALU  1989   6.1    10.2  5.3    4.2   5.2    3.3    1.8   3.4    5.1   3.8    4.3   3.2
                   NAY  1990    -       20  12.1   11.9  11.2   13.9   13.3  11.7   17.8  9.6     -    11.7
















                     Table 3. Dissolved Oxygen Levels in all Ponds for 1987-90.



















                                                                PCND
                                           2      3     4      5      6     7      8      9    10     11     12

                     MTE
                     APR 1987   7.36    7.6  7.19    7.05  6.75   7.5   7.28    7.1   8.44  7.21   6.63   7.17
                     ALO 1987   7.46    7.78 6.81    6.57  6.53   7.32  7.32    7.81  7.48  7.24   7.05   6.57
                     OCr 1987   7.37    7.83 7.76    7.39  7.23   7.27  7.62    7.52  7.57  8.16   7.13   7.55
                     AM  1988   8.29    8.25 8.48    8.1   7.81   8.41  8.03    8.6   8.5   8.76   7.67   7.92
     ON
                     AUG 1988     7.8   8.2   7.5    7.6    7.5   7.2    7.5    7.6   7.5    7.6     7.3   7.4
                     RN  1989     8.3   8.3   7.5    7.5    7.7   8.5    8.4    8.4   7.9    7.9     7.7   8.2
                     ALU 1989     7.7   8.8   7.2    7.3    7.3   6.8    7.2    7.4   7.8    7.3     7.4   7.3
                     IVAY 1990    -     9.4   8.1    8.2    7.7       9     9      9  9.4       8    -     8.3
                     ALU 1990     -     8.5   7.9    8.5    8.3   9.2    7.6       9  7.5    7.9     -     7.9











                      Table 4. pH Readings in all Ponds for 1987-90.



















                                                               FCND
                   DATE     ----- 1-----2-----  3----- 4----- 5-----6----- 7-----8----- 9 ---- 10 ---- 11 ---- 12
                   NAR 1987    91.5   89.3    119  74.2   74.9  81.4   61.9  64.1    107  64.7   77.2  73.5
                   ALO  1987     158   162    130   111    164   170   96.1   118    132    101   140    117
                   OCr  1987   77.8   72.3  48.1   52.2   75.9  47.4    118  89.1    103    105  96.3  61.6
                   FEB  1988   68.7   63.9  66.8   62.1   61.4  60.9   74.8  45.2   68.4  55.5   70.6   62.4
   U'l             ALO  1988     40    -      30    25     30    50     30    35     25     20    40     35
                   RN   1989     45    25     40    25     25    15     30    35     45     40    40     30
                   AUG  1989     45    20     40    25     35    30     30    25     35     20    25     25
                   NAY  1990     -     -      35    30     35    10     7     -      -      35    -      35
                   ALG  1990     -     25     70    35     65    -      60    -      90     80    -      45










                     Table 5. Carbon Dioxide Levels in all ponds for 1987-90.






















                                                             FCND
                   IATE     ----- 1----- 2----- 3----- 4----- 5----- 6----- 7----- 8----- 9 ---- 10 ---- 11 ---- 12-
                   IVAR 1987   0.8    0.8    0.7   0.6    0.8 0.95    0.7   1.3    0.4  0.45   0.55  0.45
                   AUG 1987    0.9  0.65   0.95   0.45  0.65  1.95    0.5   0.7  0.65   0.65   0.65  0.75
                   CCr 1987    0.7    0.5    0.5     0  0.35  0.35    0.5   0.9  0.45   0.35   0.35  0.45
                   FEB 1988    0.55 0.55     0.6   0.6  0.55    0.6  0.65   0.7  0.45   0.55   0.45  0.35
                   AUG 1988    2.28 2.16   2.16   1.56  1.56  2.16    2.4   1.56 2.04   1.68   1.68  2.04
                   RN  1989    2.4  1.56   1.68   1.56    1.8   1.8  2.04   2.04   2.4  2.04     -     2.4
                   ALG 1989    0.96 0.72   0.45    1.2  1.32  1.92    1.68  1.56   0.6  0.96     0.6 1.08













                    Table 6. Ammonia Levels in all Ponds for 1987-89.



























                                                 FCND
                          1     2    3    4    5    6    7     8    9   10   11    12
               DITE
               IVAR 1987 2100 1610 3620 1720 1490 1070 1140 1060 4040 1560 2870 2570
               APR 1987 6050 5640 5380 3720 4390 2860 3630 3560 4980 4050 5400 4080
               OCr 1987 4710 4390 3040 3510 3520 1830 4900 4070 6090 5070 6280 3160
               FEB 1988 7530 5620 7410 6270 4520 3160 4070 3380 9000 5620 9140 7770















                Table 7. Sodium Levels in all Ponds for 1987-89.



























                                                     FCND

                             1    2     3    4     5    6     7    8     9    10   11     12

                 DATE

                 IVAR 1987 11300 9380 18600 9840 8540 6530 6920 6600 20800 9240 15600 14200
    00
                 APR 1987 8740 8360 9000 6040 5990 4230 5600 5810 7790 6520 8180 6520

                 OCF 1987 3710 3620 2670 2960 3330 2140 4120 3700 4740 4370 4700 3250

                 FEB 1988 4450 3920 4650 4240 3540 2850 3320 2800 4620 3500 4490 4060
















                  Table 8. Chloride Levels in all Ponds for 1987-88
























                                                         PCIND

                                1     2     3     4    5     6     7     8      9    10    11     12

                  rATE

                  MAR 1987 21800 18200 33000 18500 15900 12100 13000 12900 35200 17000 28200 25900

                  APR 1987 24000 24000 23200 17000 20500 14000 17900 18000 24000 20200 25400 20100
     ON
     'IO          OCr 1987 23500 22200 15000 17000 18500 10900 25000 21500 30000 26500 29000 17900

                  FEB 1988 33000 25500 32900 28200 22500 16600 20200 16800 38200 36000 38800 34000

                  ALG 1989 24000 17200 39500 17800 12900 5800 10100 7800 37100 17700 25500 30400
















                    Table 9. Conductivity Readings in all Ponds for 1987-89.




























                                                              FCND

                                   1      2     3      4    5       6     7      8     9     10     11    12

                    ERTE

                    IVAR 1987   268   179     429   147   110 73.7      92 76.8     479    110   279     223

                    APR 1987    229   219     200   122   156 83.6      107    113  175    134   183     137
                    OCr 1987    254   210    84.5  94.1  89.7 40.3      135    118  182    141   165    74.1
                    FEB 1988    164   123     155   135   101      71    94     80  184    119   190     165















                     Table 10. Hardness Readings in all Ponds for 1987-88.
























                                                                 PCND
                     EATE     -----  1----- 2----- 3----- 4----- 5----- 6----- 7----- 8----- 9 ---- 10 ---- 11 ---- 12-
                     TVAR 1987  19.1   17.3   26.5   15.7  14.5   13.3   12.2   12.4  29.1   15.3   21.8   21.3
                     APR 1987   32.6   22.8   22.4      18 24.2   17.1   19.3      19 26.4      22  26.8   23.6
                     OCr 1987   16.1   16.8   13.1   15.9      18 12.1   20.7   18.2  22.9   23.6   24.4   19.9
                     FEB 1988   14.3   11.7   13.6   12.6  9.94   8.09   9.71   8.81  15.9   11.8   16.7   16.1
                     ALO 1988   13.2   17.6     8.8  13.2  13.2     8.8  13.2   13.2  13.2   13.2   13.2     8.8
                     RN  1989   13.2   13.2   13.2   13.2  13.2   13.2   13.2   13.2  13.2   13.2   13.2   13.2















                      Table 11. Nitrate Levels in all Ponds for 1987-89.



























                                                           PCND

                                1      2     3      4     5     6     7     8     9    10     11    12

                   MTE

                   ALG 1988   0.5    0.7   0.5   0.4    0.5     1   0.3   0.5   0.2   0.3   0.4   0.7

                   JLN 1989   0.4      2     1    1.9   2.7   2.3   0.1   0.1   0.1   0.1   0.8   0.1

                   ALE; 1989  0.1    0.2     0   0.3   0.1    0.2     0   0.5   0.1   0.4   0.2   0.1
















                    Table 12. Ortho Phosphate Readings in all Ponds for 1988-89.









         biological limiting factors to the health and productivity of the

         ponds and are similar to permanent natural marsh pools.


                  GREAT MARSH EMERGENT AND SUBMERGENT VEGETATION


              Predominant vegetation typing was assessed prior to pond
         site selection and installation in 1986  @r in order to compare
         recovery rate and success of waterbird usage between different

         vegetative species and to assess submerged aquatic vegetation

         growth.

              There are three dominant species     Spartina patens and

         Distichilis spicata collectively called   salt hay, and Spartina

         alteriflora. Salt hay typically occurs    around the perimeter of

         wooded hummocks and in small areas in the open marsh. S.

         alterniflora is the dominant vegetation occurring in areas more

         frequently flooded by tides. Species which occur along ditch

         edges, upland and old spoil mounds include the shrubs Iva

         frutescens and Baccharis halimifolia and a non-desirable grass

         Phragmites australis.

              Pond excavation involves removing spoil from the proposed

         site and depositing it over the marsh surface. It is critical

         that spoil deposition be kept to a minimum because there is a

         small window of a few inches where vegetation changes will occur.

         Previous studies have shown that a change of just 2-3 inches,

         either by raising the marsh surface or lowering the water table,

         will cause areas of S. alterniflora to convert to salt hay and

         salt hay to convert to shrubs.

              The objective of emergent vegetation recovery following pond



                                     73








        excavation,was to have the S. alterniflora ponds return to

        original or salt hay if spoil,deposition proved to be higher than

        desirable. In the case of salt hay constructed ponds, spoil

        levels had to be kept to a minimum to avoid invasion by

        undesirable species such as shrubs or Phragmites.

             The dominant species of submerged aquatic vegetation is

        widgeon grass (Ruppi maritima). It is well known as an

        important waterfowl food. It also harbors many aquatic

        invertebrates important for duck broods and feeding waterfowl and

        fish. An algae which occurs in abundance is Cladophora which

        may also be important as a food source, however excessive

        coverage can shade out widgeon grass.

             Emergent vegetation patterns and recolonization of spoil

        areas around the IMM ponds was initially evaluated during 1988

        using false-color IR aerial photographs taken in October, 1988

        and by ground reconnaissance. Spoil areas around ponds located

        in high-marsh areas vegetated by Spartina patens and Distichlis

        spicata (salt hay) exhibited substantial regrowth (ca. 50-90%) of

        these original emergent vegetation species. The opportunistic

        plant species Pluchia which colonized fresh spoil areas around

        these ponds in 1987 was largely replaced by these original salt

        hay vegetation species during 1988. Additionally, a few clumps

        of S. alterniflora colonized spoil areas around these ponds.

        Some spoil areas around closed ponds located in high-marsh areas

        were unvegetated, apparently due to extended periods of

        inundation resulting from water overflow from these ponds. Spoil

        areas associated with semi-tidal high-marsh ponds exhibited more



                                   74







        complete revegetation than high-marsh closed ponds. Upland edge

        spoil areas are largely revegetated by the original plant

        community consisting of Iva, Baccharis, and Myrica shrubs. Some

        ephemerally flooded high-marsh pond bottom and perimeter areas

        have been colonized by S. alterniflora.

             Vegetation recovery around low-marsh ponds excavated in S.

        alterniflora areas progressed slower than around high-marsh

        ponds. Semi-tidal low-marsh ponds exhibited more complete

        revegetation than closed low-marsh ponds, apparently the result

        of excessively high water tables and marsh surface inundation

        around the closed ponds. Approximately 20 to 50 percent of the

        spoil around low-marsh ponds has been revegetated by S.

        alterniflora, resulting in a mix of vegetation and mudflat around

        each pond.

             Ditch spoil plugs installed in tidal-grid ditches in order

        to stabilize pond water levels were vegetated by the surrounding

        grass species. A few higher spoil plugs were colonized by Iva

        and Baccharis shrubs.


             The emergent vegetation was again assessed in 1990, four

        years after installation of the ponds. Gross recovery of

        existing vegetation was compared to original vegetation species

        and percent recovery of vegetated area to spoil was determined.

        The twelve ponds surveyed were equally divided among dominant

        species of salt hay and S. alterniflora. After four growing

        seasons, 10 of the 12 ponds have vegetation recovery ranging from

        90-100%. Figure 41 shows a pond constructed in salt hay habitat

        with near 100% recovery. The remaining two ponds are 75 and 50



                                    75
















































              Figure 41. Near 100% Vegetation Recovery Around Perimeter
                          of Pond Following Four Growing Seasons





                                    76








         percent re.covered. These two ponds which have not fully

         revegetated wer e constructed in areas of low marsh S.

         alterniflora. During flooding events the water exceeds the banks

         of the ponds and remains on the marsh surface for extended

         periods of time inhibiting germination and growth of vegetation

         (Fig. 42). Although the original intent was for full recovery,

         there are some benefits associated with these mudflat/flatpan

         areas. Waterbird use, particularly shorebirds, has remained

         fairly constant in the pond with 50% recovery whereas the ponds

         whose recovery has progressed year to year towards full recovery,

         shorebird use has diminished.

              Care must be taken to keep spoil deposition to a minimum,

         particularly in high marsh areas. Ponds with remaining recovery

         of 5-10% can be partly attributed to excess spoil. In areas

         where possible, spoil can be deposited in upland vegetation to

         reduce spoil deposition on the marsh surface. Figure 43 depicts

         pond site soon after construction in February, 1987 and

         vegetation recovery in 1989.

              The recovery of vegetation from original species to as it

         exists today demonstrated 75% of the ponds returning to pre-

         excavation conditions The six S. alterniflora areas recovered to

         S. alterniflora as the dominant species. Two of the six salt hay

         areas recovered to predominantly salt hay with Baccharis

         halimiflora the secondary species ranging from 15-30 percent.

         Unexpectedly, three of the salt hay areas recovered to S.

         alterniflora ranging from 40-90 percent dominance probably caused

         by raising the water table in the immediate area and keeping



                                    77


































                                                             -11 -e-t































             Figure 42. Approximately 50% Vegetation Recovery Around
                         Perimeter of Pond Following Four Growing Seasons.







                                      78














                                     "sop,













































                                          -low














            Figure 43. Pond Following Construction and Recovery






                                     79








        spoil heig4t to a minimum. This is considered a positive result

        as S. alterniflorais more important in terms of nutrient

        exchange with the estuary.

             The predominant submerged aquatic vegetation (SAV) in these

        salt marsh ponds is Ruppia martima. Ruppia normally first

        appears and is most abundant in early to mid-summer, May - July.

        SAV appeared during the first growing season, 1987, in three of

        the twelve ponds. The dominant emergent vegetation of these

        areas was salt hay. In 1988, Ruppia was present in six of the

        ponds but only three contained significant amounts (maximum of 45

        to 97 percent) (Table 44). Of the additional three colonized

        ponds two were again in areas of salt hay vegetation. The 1990

        survey showed there were seven ponds containing SAV, with

        percentages ranging from maximums of 40-90 percent, (Fig 44). Of

        the ponds surveyed only one S. alterniflora constructed pond

        contained Ruppia. Figure 45 compares percentage of Ruppia growth

        in the ponds of salt hay and S. alterniflora habitat. All of the

        ponds constructed in salt hay had Ruppia growth ranging from 75-

        90% maximum coverage. Only one pond constructed in S.

        alterniflora habitat contained Ruppia and was lower in total

        coverage (40%). An algae, predominantly Cladophora, was present

        in small amounts in four of the twelve po nds during 1987. In

        1988, seven ponds contained Cladophora in slightly larger amounts

        ranging from 1-79 percent. By 1990, every pond had varying

        amounts of algae ranging from 1-75 percent. The ponds with the

        largest percentage of algae were ponds constructed in salt hay

        areas with percent coverage from 60-75% maximum while S.



                                    80





                                             GREAT MARSH
                                   SUBMERGENT VEGETATION


                        PERCENT
                   100



                    80-



                    60-                                                                            . . .... . .........



                    40-                                                  ........... ... ... .................... ....... ........ .... ...



                    20-                                           .... ......                   . .. .....  ...... --- ...............



                      0                 ------
                           1      2      3      4      5      6      7       8      9      10      11    12
                                                              POND


                                                          1988           1990



               PERCENT COVERAGE

                   Figure 44. Percent Coverage of SAV (Ruppia maritima) in all Ponds for 1988-90








                                                                            GREAT MARSH
                                                                SUBMERGENT VEGETATION

                                                  PERCENT
                                           100


                                             80--                                ...........-..................... . .........-..................... ...........  -.1 ...........................................................


                                                                                                                                      ............................
                                             60-
                                                                                                                                            ..................

                                                                                                                                      ............
                                             40   . ........                                                                          .........          ....................
                                                                                                                                      ............................


                                                                                                                                      ...............
                                             20---


                                                                                                                                                 ..........
                                                                                                                                             ...............
                                               0

                                                                                                   POND

                                                                            2              5       = 6                    7              8


                                      % COVERAGE BY EMERGENT VEGETATION TYPE-
                                      SALY HAY








                                               PERCENT
                                           so



                                           40-                                                                           ..... .. ............................ ...........-.......... .......................



                                           30--                                                                          ......................  ..........  ............ ........... ..... ..........



                                           20-                                                                        ............           ..........................  -- ....................




                                                             .................................-                    . ...... ................. ...........  .................................................. ......................
                                           10-



                                             0

                                                                                                  POND

                                                                          3              4              9              10       M5 12


                                      % COVERAGE BY EMERGENT VEGETATION TYPE-
                                      SPARTINA ALTERNIFLORA

                                      Figure 45. Percent Coverage SAV (Ruppia maritima) by two
                                                              Vegetation Types in 1990

 'A








                                                                             GREAT MARSH
                                                  % COVERAGE             CLADOPHORA ALGAE
                                            100


                                             80-



                                             60--                              ...........     .......... .                                ............ ........... ... ..... ............... .................


                                             40-                                        ...........                                                ... .......... .....................



                                             20                                            ............. .... ... ..                    ............ ..........  ...............I. ...... ............
                                                0                           __m                                                                Rm
                                                            2                                            6                     7                       8
                                                                                                    POND


                                                                                              1987                1990


                                      PEAK % COVERAGE IN SALT HAY HABITAT




                                                                         CLADOPHORA ALGAE

                                                  % COVERAGE
                                            100


                                             80-


                                             60-



                                             40-



                                             20-



                                                0
                                                            3                     4                     9                     10                     12
                                                                                                    POND


                                                                                              1987                1990


                                     PEAK % COVERAGE IN S. ALT. HABITAT
                                      Figure 46. Percent Cladophora Algae by Two Vegetation Types in
                                                               1987 and 1990








        alterniflora areas ranged from 2-15 percent (Fig. 46). There

        appears to be a correlation between percent coverage of

        Cladophora and Ruppia. The higher the percentage of surface

        coverage on the pond surface, Ruppia tends to be reduced.

             The colonization of Ruppia appears to be correlated to pond

        depth and substrate. The ponds constructed in salt hay areas

        generally have a firmer bottom than S. alterniflora areas

        allowing a better "foothold" for rooting. Depth of pond, which

        affects light penetration, can also affect Ruppia colonization.

        Mahaffy (1987) has shown that ponds with a depth greater than

        0.5m have little or no Ruppia growth. As shown in figure 45,

        restored ponds (9 and 10) are generally deeper and constructed in

        S. alterniflora habitat and contain no Ruppia growth.




                            GREAT MARSH INVERTEBRATES

             Invertebrate sampling of the twelve ponds was conducted in

        1987-1990. During the first two years, samples were collected by

        a graduate student from the University of Delaware working full

        time on this project. However, the student failed to pass the

        comprehensive exam and responsibility for data collection,

        analysis and writing the final report became the Division of Fish

        and Wildlifels. Although intensive data collection during 1989

        and 1990 was not possible, invertebrates were sampled during

        times when availability of adequate populations of invertebrates

        would be utilized by any waterfowl broods which would be

        produced, as almost 100% of the broods diet is animal protein.

        These invertebrates are also important to spring and fall



                                    84







         migrating shorebirds in addition to wintering black ducks and

         sustaining fish populations. ,

             Sampling procedure involved sweeping a section of pond edge

         and aquatic vegetation with a D-shaped sweep net (Fig. 47).

         Collected samples were sorted, counted and identified to order.

         Two samples per pond were collected.

             Data analysis of invertebrate populations involved consider-

         ation of various scenarios. Between pond comparisons of total

         invertebrates per pond per sample is shown in Figure 48. The

         most revealing differences depicted in this table is the overall

         increase of invertebrates from 1987-88 to 1989-90. This is

         attributed in part to establishment of populations over a period

         of time and an increase of emergent and submergent vegetation.

         Large numbers of gastropods and crustaceans, were captured among

         the dense SAV Ruppia. All ponds appear to harbor adequate

         populations of aquatic invertebrates to support any broods

         produced and sustain wintering waterfowl as certain species rely

         on gastropods as other food sources become scarce. Figure 49

         combines all ponds and separates invertebrates by order. Six

         orders of aquatic invertebrates were collected including

         Coleptera, Diptera, Hemiptera, Odonata, Crustacea and Gastropoda.

         Within these six orders were 19 families of invertebrates. Catch

         per effort increased for each year during 1989-90 from the two

         previous years. The majority of the sample was from the order

         Crustacea, mainly amphipods, and gastropoda - snail species

         including Melampus, Nassarius, Physidae, and Littorina.

             Before construction began, some obvious site specific



                                    85


















































             'Figure 47. Invertebrate Sampling at Great Marsh.








                                      86








        differences among the ponds and adjacent areas existed. In order

        to amlmlrew useful management options for future construction based

        on invertebrate populations, the selected sites were separated

        into different categories. The basic and most obvious

        differences include man-made ponds and previously drained

        restored ponds and ponds constructed in salt hay (Spartina

        patens and Distichilis spicata) zones and S. alterniflora zones.

        Generally, the man-made ponds are more shallow with tapered sides

        then are restored ponds. Overall, number of invertebrates per

        sample was slightly higher in the man-made ponds for Coleoptera,

        Diptera, Hemiptera and Odonata whereas Crustacea was similar in

        abundance. The largest difference-were Gastropods which are

        approximately five times more abundant in man-made ponds (Figure

        50).

             Figure 51 shows differences in invertebrate populations

        within salt hay and S. alterniflora constructed ponds. The major

        difference among the two vegetation types are within the orders

        Gastropoda and Crustacea. Large numbers of Gastropods were

        captured within the salt hay ponds particularly in 1989 and 1990,.

        whereas S. alterniflora ponds were approximately 8 times less.

        Crustacean populations within S. alterniflora ponds for 1988-1990

        were approximately twice as high as salt hay ponds. Number of

        Crustacea for 1987 were similar for both vegetation habitats.

        The orders Coleoptera, Diptera, Hemiptera and Odonata were

        slightly higher in salt hay ponds for all years. As described in

        the submergent aquatic vegetation section, SAV occurs more

        frequently in salt hay constructed ponds as S. alterniflora



                                   87





                   GREAT MARSH INVERTEBRATES

                      NO. INVERTEBRATES
                   30





                                                                                        . . ..... . ..
                   25





                                                                                                      ..........
                   20 -



                   15



                   10-





                             .. .... .... ..                         ...     ...           ...

                                 ...    ...     ....
                                 ....   ...     ...

                                     jjjjj'@@
                                     NIP_
                     0
                         1      2      3       4      5      6       7      8      9      10     11      12
                                               INVERTEBRATE ORDER


                                          1987           1988           1989            1990



              TOTAL NO. INVERTEBRATES/POND/SAMPLE
                Figure 48. Number of Invertebrates Per Sample in all Ponds for 1987-90





                   GREAT MARSH INVERTEBRATES

                      NO, INVERTEBRATES
                   50



                   40-


                                                                                        .... ...      ....


                                                                                        ...... .      .....

                                                                                        ........      ....-
                   30


                                                                                        ........      ........



                                                                                        .... .        ........
                                                                                        ....          ... ...
                   20
                                                                                        .....         ........
                                                                                        ....          ........




                                                                                        ......        ......
                                                                                        ......        .......


                                                                                        . ......      ........
                                                                                                    .......... .
                                                                                        ......        ........
                   10-




                                                                                        ......        ....


                     0
                      COLEOPTERA DIPTERA HEMIPTERA ODONATA                       CRUSTACEA GASTROPODA
                                               INVERTEBRATE ORDER
                                                                         @@r I

                                          1987           1988           1989            1990



              TOTAL NO. INVERTEBRATES/POND BY ORDER

               Figure 49. Number of Invertebrates per Pond by Order in 1987-90








                          GREAT MARSH INVERTEBRATES
                                               MAN-MADE PONDS

                             NO. INVERTEBRATES
                          60



                                                                                          .....................
                          so-


                          40-                                                      . . . . ........................



                                                                                            ..........
                          30-                                                      ...        ...


                                                                                           ...............
                          20-


                                 _17M
                                                      ..........         ..........
                          10-


                             01
                             COLEOPTERA DIPTERA HEMIPTERA         ODONATA CRUSTACEAGASTROPODA
                                                  INVERTEBRATE ORDER

                                        MI 1987      M 1988      Ell 1989     M 1990


                       TOTAL NO. INVERTEBRATES/POND BY ORDER




                                               RESTORED PONDS

                             NO. INVERTEBRATES
                          35


                          30-


                                                                                ..........   ............ ... .... - -
                          25-


                                                                                .......... ....  ............................. .................................
                          20-


                                                                                           ...................



                                                                                           .............
                          lO_.


                                                                                               ....... ....



                             COLEOPTERA DIPTERA HEMIPTERA ODONATA CRUSTACEACIASTROPODA
                                                 INVERTEBRATE ORDER


                                            1987         1988         1989         1990


                       TOTAL NO. INVERTEBRATES/POND BY ORDER

                       Figure 50. Number of Invertebrates per Pond by Order in
                                      Man-Made and Restored Ponds in 1987-90








                             GREAT MARSH INVERTEBRATE
                                 NO. INVERTEBRATES           SALT HAY
                             100



                              80----                             . . . . .. .. ..... . ..... ..... .. ...



                              60-                                                               ........................



                              40-              . ... ..



                              20-                                                       17,71



                                 0
                                 COLEOPTERA     DIPTERA HEMIPTERA ODONATA CRUSTACEAGASTROPODA
                                                      INVERTEBRATE ORDER

                                                 1987     M 1988       = 1989             1990


                         TOTAL NO. INVERTEBRATES/SAMPLE BY ORDER





                                            SPARTINA ALTERNIFLORA

                                 NO. INVERTEBRATES
                             60



                                                                                                  . ..........-...........................
                             50-


                             40-


                             30-                                                                    ......................


                             20-                                                                       .............. .......


                             10-                                                 ............ ..........


                              Ol
                                 COLEOPTERA DIPTERA HEMIPTERA ODONATA CRUSTACEAGASTROPODA
                                                      INVERTEBRATE ORDER                              77-
                                                 1987    M 1988        = 1989             1990


                         TOTAL NO. INVERTEBRATES/SAMPLE BY ORDER


                          Figure 51. Number of Invertebrates per Pond by Order in
                                          Two Vegetation Types in 1987-90





                           GREAT MARSH INVERTEBRATES

                                NO. INVERTEBRATES
                           20






                                                                            .............
                                                                            .......... .............
                                                                            . ...... ... .......
                                                                            .......... ......
                                                                            ........ ...... ........

                                                                            .. . . ........
                                                             ..... .... .                      ......... ... ..... .............
                           15-

                                                                            .... .... ....
                                                                            .......................
                                                                            ..........-......
                                                                            .................
                                                                            ............ .......
                                                                            ............
                                                                            ............
                                                                            ........ ...
                                                                            ........... ... --l.-
                                                                            -............
                                                                            ................-.......
                                                                            -..... -.1 ..........
                                                                            ...... ... .... .........
                                                                            ..............


                                                                            ...... . ......... ..

                                                                            . ........ ..... .
                                                                            ............. ...-..... .
                                                                            ...........
                                                                            .. .... .. ...... ...
                                                                            .. .......... .. ....
                                                                                                 ........... ...                     ............
                           10
                                                                            ..... .... ..

                                                                            . .... ....... ......
                                                                            ......                                              .... ........
                                                                            .... .......
                                                                            . ..... . ... ....


                                                                            ..........
                                                                            . .. ....... ...-

                                                                            .......                                             .....
                                                                            .. .......                                          ....
                                                                            ........                                            ....
                                                                            ................. ...                               ...
                                                                            ... ...........                                     .....      ....
                                                                            ...                                                 .....      ....
                              5                                             ...........       ....... .....                     ............
                                                                            ...........                                         ...... .
                                                                            .. .........
                                                                            ............                                        ...... ..
                                                                            ............                                        ......
                                                                            ......                                              ....-
                                                                            .......... .........                                .....
                                                                            ... . ...                                               .... ......  .......
                                                                                                                                   . ....................
                                                                            .... ......

                                                                            .... ............
                                                                            ...... ...                                          .. ...
                                                                            ..........
                                                                            .... ........ .........                             ......
                                                                            . ........................
                                                                            ................



                                                                            ................
                                                                            ....-.......                                        ...
                                                                            .............. ..........
                                                                            ...........
                                                                            ..........
                              0
                                                              SAV                                                        NO SAV
                                                                                                      0 0 1 -: "-         EmFm,;


                                                               1987                 1988                  1989                  1990



                     TOTAL INV. BY SUBMERGENT VEG. TYPE


                       Figure 52. Number of Invertebrates in Ponds With or Without SAV








        areas. It, appears that invertebrate abundance may be related to

        SAV growth with in the ponds as overall abundance is larger in

        ponds containing high percentages of SAV (Figure 52).



                                  BROOD SURVEY


             Brood surveys were conducted at Great Marsh via helicopter

        during 1986-88. Peak brood production periods of the year were

        selected in June and July. Transects were flown over the entire

        2300 acres of Great Marsh, taking special note of the IMM areas

        both pre- and post-treatment. The flights were scheduled during

        the morning and averaged 1 hour and 10 minutes.

             Table 13 shows the results of the aerial brood survey.

        Waterfowl production was very poor throughout the area. The

        black duck was the only brood species observed with a maximum of

        two broods per nesting season. There were no broods located

        within the ponds or IMM area during pre- or post-treatment.

        Nesting waterfowl and broods have been observed adjacent to and

        on the IMM ponds during scheduled waterfowl observation surveys.

        However, successful brood production is less than originally

        hoped for considering the new available habitat.

             Predation is evidently high due to the large number of foxes

        and raccoons observed during waterfowl observations. Actual nest

        predation by a fox was observed on a gadwall nest.













                                    93











                            GREAT MARSH BROOD SURVEY



                                   BLACK DUCK


           12 JUNE 1986             4-IIA, 5-111

           11 JULY 1986                   0


             2JUNE  1987                  0


             7JULY  1987             1-IB, 4-IIA

           22 JUNE  1988                3-IIB


           20 JULY  1988                6-111




             NO BROODS WERE LOCATED IN PRE- OR POST IMM STUDY AREAS.































              Table 13. Great Marsh Brood Survey, 1986,-88.








                                        94










                                FISH POPULATIONS
             Fishand s .elect aquatic invertebrate populations were

        surveyed in the 12 ponds during the summer and fall of 1987. Two

        15 meter sections of the pond were blocked and sampled using a 15

        foot seine. Fish and invertebrates captured were identified to

        species and counted. Totals of each species were divided by

        number of seines to obtain catch per unit effort. The objective

        was to determine if fish populations were large enough to

        eliminate any mosquito brood that may be produced within the pond.

             A total of six fish species and two invertebrate species

        were collected. Fish species collected in order of abundance

        include: Cyprinodon variegatus, Fundulus heteroclitus, Lucania

        parva, F. luciae, Menidia beryllina, and F. majalis (Table 14).

        Two species of crustaceans were captured including Palaemonetes

        pugio and Callinectes sapidus (Table 14). Catch per unit effort

        data indicates that during the summer there was a range of a low

        of 68 to a high of 469 fish per seine effort for all ponds.

        During the fall the range was 33 to 363 per seine effort. All

        ponds contain adequate numbers of fish to prey upon any mosquito

        larvae that would be produced in the ponds. P. pugio were most

        abundant in the fall and C. sapidus was found in low numbers

        during all these seasons. These fish species are not only

        important as mosquito larvae predators, the fish and crustaceans

        also serve as a food source for many waterbirds including herons,

        egrets, gulls, terns and kingfishers. Qualitative checks during

        various periods of the year from 1988 - 1990 indicated large fish

        populations in all ponds.



                                   95







                                                                                GREAT MARSH FISH SN'LING
                                                                                          1987


               F.heteroclitus        C. variegatus         L. parva             F. luciae       F. majalis         M. beryllina          P. pugio           C. sapidus
      KIND      SUMMER   FALL        SUM- MER FALL      SUMMER   FALL       SUMIMER FALL      -WMMER    FALL      SI.NMER FALL       SIJMMER FALL          SUMMER   FALL
        1          48      14         195     214          1        -                    2                                    2                 19
        2           6       5          61      59          1       14                    -                                    -          6      16
        3          44       4         117      11          -        -           I                                             -         13      40
        4          22       2         312     4N2          -        4           -                                    -        6          -      Its
        5          30      16         102      40          2        2           1        1                           4        -          8      84
                                      11%                                                                            -                          78
        6          95      16          4-6     61                   1           2        1                                            12 -S
        7          52-     30          64     115          2        1)          2        -                           2                   1      60
        8          12      30         276     188          1        2                                                1                   1      158
        9          87      128         24     2321         -        2                                                                    4      72
        10         2:3     180         219     6-S         1       to           1                                             20
        It         32      17         0        28          -        1           2                                             1          2      62
        12         42       3          78      78                   -           -                                             -          -      24





                    Table 14. Fish Sampling Results in all Ponds in 1987










                                MOSQUITO REDUCTION

             Historical Mosquito breeding sites of Aedes  sollicitans were

        eliminated by the construction of the 12 ponds and additional

        OMWM work. No mosquito breeding was observed in any of the ponds

        due to large resident fish populations and by destruction of

        mosquito breeding habitat. The limited number of mosquito

        producing depressions caused by equipment (ruts from heavy

        machinery) were eliminated by excavating radial ditches from the

        pond and ditches to the breeding areas. These ditches allow

        predatory fish access to mosquito producing locations. This 2300

        acre area was once routinely aerial sprayed with larvacide. This

        practice has now been eliminated.


































                                    97










                          DISCUSSION AND RECOMMENDATIONS


             When the Great Marsh project was undertaken in 1986, omwm

         techniques were well established. OMWM ponds are generally small

         (one-tenth of an acre or less), but served their purpose of

         eliminating multi-depression mosquito breeding habitat while

         providing some permanent water for waterbirds. It was felt that

         large ponds (one-half acre or more) would provide a more

         attractive habitat for many species of waterbirds. A similar

         study conducted by Mike Erwin (Patuxent Research Center) found

         that larger ponds in fact are more desirable than standard OMWM

         ponds (results not published at time of this writing). The

         primary objective for the larger ponds was for waterfowl

         enhancement. However, due to construction techniques such as

         tapered sides and depths of 4-18", these ponds became quality

         habitat for various species including waterfowl, shorebirds,

         wading birds, gulls and terns and other species such as osprey

         and kingfishers. Additionally, these ponds are large enough to

         be effectively partitioned by creating islands to allow non-

         competitive utilization. Many marshes can benefit by creating

         and restoring ponds due to their degraded nature (i.e. grid

         ditched areas). In many cases, as with Great Marsh, these ponds

         are helping to restore marshes to their original condition. Even

         with the 12 created or restored ponds on Great Marsh, there

         remains a net loss of 25 acres of non-tidal pond habitat.

              The following list summarizes major points and provides some

         potential management suggestions:

              1) Overall, the ponds, both manmade and restored, were


                                    98









        utilized considerably more than typical natural marsh areas

        associated with Great Marsh. Areas of marsh containing little or

        no water habitat provide very little usable habitat for feeding

        and resting waterbirds. A large percentage of Delaware's marshes

        are degraded due to grid-ditching. As previously stated,

        installation of.mew ponds and restoration of existing tidal ponds

        help mitigate the loss of permanent water. Routing installation

        and enlarging of ponds in multi-depression mosquito breeding

        habitat in degraded or non-degraded marshes will provide

        increased and enlarged habitat for all guilds of birds observed

        in this study and all parameters surveyed.

             2) Natural flat pan areas, during certain periods of the

        year, particularly spring, are utilized similarly as the ponds

        for waterfowl and shorebirds. Green-winged teal and black ducks

        use these areas routinely when available. Wading birds and gulls

        and terns prefer the deeper habitat the ponds provide with the

        capability of supporting fish populations. If these flat pans

        are determined to be non-mosquito breeding habitat, it would be

        beneficial to leave untouched since no work or marsh disturbance

        is necessary and they provide certain benefits. As a subjective

        aside, flat pan areas were fortuitously created by a trac-vehicle

        in non-breeding S. alterniflora. These areas are now routinely

        utilized by shorebirds and waterfowl. These  pans could be

        created, provided there is routine flooding to prohibit mosquito

        breeding, due to low cost of installation and minimal marsh

        surface disturbance.


             3) As previously discussed, ponds were constructed in two


                                   99









        vegetation types, salt hay (S. patens and Distichilis spicata)

        and S. alterniflora. Salt hay ponds generally exhibited fuller

        recovery of vegetation. S. alterniflora created ponds sometimes

        have standing water around the pond perimeter retarding

        vegetation growth - however, shorebirds continued to utilize

        these areas whereas other ponds whose vegetation recovery was

        near 100%, shorebird use diminished.

             Salt hay created ponds have a higher potential for unwanted

        species such as Iva, Baccharis and Phragmites. These are

        typically high marsh species and excess spoil can cause surface

        elevations around the perimeter of the pond to be raised.

        However, in two instances salt hay created ponds converted to S.

        alterniflora as the dominant species, possibly caused by raising

        the water table in the immediate area with permanent water and by

        keeping spoil height to a minimum.

             4) Submergent aquatic vegetation (SAV) generally occurs in

        salt hay created ponds while S. alterniflora ponds typically

        contain little or no widgeon grass (Ruppia maritima). Of the

        ponds surveyed in the study, all of the salt hay created ponds

        contained Ruppia ranging from 75-90% by 1990. Only one pond

        created in S. alterniflora habitat contained Ruppia with a

        maximum of 40% coverage. In order for Ruppia to colonize salt

        marsh ponds, the substrate generally needs to be firm and depth

        no greater than 0.5m.

             A species of algae, Cladophora occurs naturally in many salt

        marsh ponds. Ponds constructed in salt hay zones had larger

        percent coverage than did S. alterniflora zones ranging from 60-


                                    100









         75% and 2-15% inclusive.  These mats of algae tend to shade out

         and kill Ru2Pia. However, Cladophora does harbor large

         quantities of invertebrates such as snails and amphipods as black

         ducks have been observed feeding among the algae seiving

         invertebrates. In addition, invertebrate abundance may be

         related to SAV growth as overall abundance was greater in ponds

         containing SAV.

             Generally, invertebrates are more abundant in manmade ponds

         versus restored ponds. Salt hay constructed ponds contain larger

         numbers of Gastropods while larger numbers of Crustaceans were

         observed in S. alterniflora ponds. The remaining order of

         Coleoptera, Diptera, Hemiptera, and Odonata were higher in salt

         hay ponds.

              5) Manmade ponds overall were utilized more frequently for

         all guilds, and on a year-round basis, than restored ponds.

         Shorebirds in particular benefit from the shallower design.

         Gulls and shorebirds utilize the exposed spoil for feeding and

         resting. However, bay species of waterfowl such as buffleheads

         and mergansers prefer restored ponds deeper habitats.

         Additionally, in some instances restored ponds are utilized by

         waterfowl during cold periods when the shallower ponds freeze

         over. Restored ponds are very worthwhile, incorporating into a

         system design, considering the minimal amount of work and

         perturbation on the marsh surface, usually requiring one or more

         plugs of ditches.







                                    101












                                    REFERENCES


         Berger, H., "The Value and Importance of Limiting Concentrations
              in Determining the Hygenic Quality of Water." Part I, XL.
              Mitt. Ver. Waser-, Boden -, and Lufthyg. 18 115 (1942);
              Water Pollution abs. 16 (Dec. 1943).

         Brockway, D. R., "Metabolic Products and Their Effects." Prog.
              Fish Culturist 12, 126 (1950).

         Doudoroff, P. and M. Katz. "Critical Review of Literature on the
              Toxicity of Industrial Wastes and Toxic Components to Fish."
              Sewage and Industrial Wastes 222, 1432 (1950).

         Ellis, M. M., "Detection and Measurement of Stream Pollution
              (Related Principally to Fish Life)." U.S. Dept. of
              Commerce, Bur. of Fisheries Bull. 22 (1937)

         Mahaffy, Lynn A. "Effects of Openmarsh Water Management on
              Submerged Aquatic Vegetation Identified by Waterfowl in
              Delaware." Published in procceding of Waterfowl and
              Wetlands Symposium, 1987.

         Reid, George K., R. D . Wood - 1976. Ecology of Inland Waters
              and Estuaries..485pp.

         Vivier, P., "Can Fertilizers be Harmful to Fish in Ponds?" Jour.
              Agr. Prat. 99, 328 (1935); Water Pollution Abs. 9 (July
              1930).





























                                    102




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