United States Environmental Protection Agency
                                     CBP/TRS 11/87

                                       August 1987
1H
541.5
.E8
078
                                     903R87007
                           Distribution of
          Submerged Aquatic Vegetation
             in the Chesapeake Bay and
                         Tributaries-1984
                               Chesapeake
                                       Bay
                                  Program

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              Distribution of  Submerged Aquatic Vegetation in

                 the Chesapeake  Bay  and Tributaries - 1984



                                     by

                         Robert  Orth1, Jim Simons2

              Ruth Allaire3, Virginia Carter", Larry Hindman5

                     Kenneth Moore1,  and Nancy Rybicki"
1.   Virginia Institute of Marine  Science
    School of Marine Science
    College of William and Mary
    Gloucester Point, VA  23062

2.   The Bionetics Corporation
    U.S. EPA-EPIC
    Vint Hill Farms Station
    Warrenton, VA  22186

3.   Dept. of Environmental and Natural Sciences
    Northern Virginia Community College
    Woodbridge,  VA  22191

4.   U.S. Geological Survey
    Reston, VA  22092

5.   Dept. of Natural Resou^ets
    Tawes Office Building
    Annapolis, MD  21 401
Funded by:  NOAA Grant No.  NA-83-AA-D-C2048
            EPA Cooperative Agreement  X-003301-01
            MD Department of Natural Resources
            Virginia Institute of  Marine  Science

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                                  CONTENTS

                                                              Page

Tables	    iii

Figures	     iv

   1 .   Introduction	      1
   2.   SAV Species	      4
   3.   Methods	      5
           Aerial photography	      5
           Mapping process	      8
           Ground truth and other  data bases	     18
   4.   Results and Discussion	     23
           Susquehanna Flats	     39
           Upper Eastern Shore	     42
           Upper Western Shore	     43
           Chester River	     43
           Central Western Shore	     44
           Eastern Bay	     44
           Choptank R iver	     45
           Patuxent River	     46
           Middle Western Shore	     46
           Lower Potomac River	     46
           Upper Potomac River	     56
           Middle Eastern Shore	     62
           Tangier Island Complex	     65
           Lower Eastern Shore	     66
           Reedville	     67
           Rappahannock River Complex	     6?
           New Point Comfort Region	     71
           Mobjack Bay Complex	     71
           York River	     72
           Lower Western Shore	     72
           James River	     73

5.  Conclusions	     74

6.  Literature Cited	     79

7.  Appendices
       A.   Species of submerged aquatic plants  found  in the
           Chesapeake Bay and tributaries	     82

       B.   Topographic quadrangles showing  the  distribution
           of SAV	     83
                                  iii

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                                   TABLES

Number                                                                Page

  1       Guidelines for  acquisition of aerial photographs 	      7

  2      List of topographic  quadrangles in Chesapeake Bay SAV
           study area	     10

  3      Area description  for  21 major sections in the Chesapeake
           Bay SAV  study area	     16

  4      Total area of SAV by  quadrangles for 1978 and 1984 ....     24

  5      Number of  hectares of SAV  for each of the major sections
           in the bay for  1978 and  1984	     28

  6      Number of  square  meters of SAV in each quadrangle of the
           21  major sections	     29

  7      Number of  square  meters of SAV in each of the density
           classes  for quadrangles  having SAV	 ,     36

  8      Frequency  of stations with SAV in upper Chesapeake Bay,
           1971-1984	     40

  9      Species of SAV  found  on vegetated transects in the tidal
           Potomac  River and  transition zone, 1984, by USGS ....     48

 10      Relative occurrence  of vegetation in the tidal Potomac
           River and estuary,  1978-81 and 1984	     50

 11       Grid locations  in the transition zone of the Potomac
           River where SAV was found  in 1984 by the NVCC survey  . .     51

 12      Total suspended solids output from primary outlet of
           Blue Plains Treatment Plant, 1982 and 1983	     63

 13      Secchi depth in upper and  lower tidal river, 1978-81 and
           1983	     64

 14      Areas of SAV at historical sites in the lower bay zone,
           1937-1984	     68
                                 iy

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                                 FIGURES
        Flight lines used to acquire  photographs  of SAV in
          Maryland and Virginia ..................      6

 2      Location of topographic quadrangles  in  the Chesapeake
          Bay ...........................      9

 3      Crown density scale for estimating SAV  bed density ....     13

 4      Location of 3 zones and 21  major  sections in the Chesapeake
          Bay for delineation of SAV  ...............     15

 5      Location of quadrangles along transition  of Potomac River
          for SAV study conducted by  NVCC .............     20

 6      Location of vegetation sampling transects in the tidal
          and transition portion of the Potomac River conducted
          by USGS in 1983 and 1984  ................     21

 7      Percent of stations with SAV  at selected  sites in the
          upper bay, 1971-1984 ..................     41
 8      Distribution of wild  celery  in  the transition zone,
          Potomac River ......................     52

 9      Distribution of Hydrilla,  coontail and milfoil in the
          transition zone,  Potomac River  .............     53

10      Distribution of sago  pondweed,  curly  pondweed and redhead
          grass in the transition  zone, Potomac River .......     54

11      Distribution of widgeongrass , horned  pondweed, Char a sp.
          and common elodea in the transition zone, Potomac River.     55

12      SAV species diversity in the tidal Potomac River, 1983  . .     57

13      SAV species diversity in the tidal Potomac River, 1984  . .     58

14      Distribution of Hydrilla in the tidal Potomac River in
          1983 ..........................     60

15      Distribution of Hydrilla in the tidal Potomac River in
          1984 ..........................     61

16      Trends in SAV coverage at  historical  sites in lower Bay
          zone,  1937-1984 .....................     70

17      Trends in SAV occurrence in the upper Chesapeake Bay ...     77

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                                 SECTION 1




                                INTRODUCTION



     Communities of submerged aquatic vegetation (SAV)  are an  integral  part




of the Chesapeake Bay ecosystem.   They provide an important habitat  for many




species which use SAV either as a food source or as protection from




predators, e.g. a nursery.   They reduce currents and baffle waves, allowing




for deposition of suspended material.  In addition, they bind  sediments with




their roots and rhizomes to prevent erosion of the underlying  material.




They are important in nutrient cycling both through the absorption and




release of nitrogen and phosphorus (Thayer, et.  al, 1975;  Kemp,  et.  al.,




1984; Orth, et. al.,  1984;  Ward,  et.  al.,  1984).




     Interest in Chesapeake Bay SAV communities  by scientists,  resource




managers and the public has been very high because of the significant




reductions of SAV in many areas compared to luxurious stands that once




prevailed less than 20 years ago (Orth and Moore, 1981, 1983,  1984).  The




recently completed Chesapeake Bay Program, funded by the U.S.  Environmental



Protection Agency (EPA) , focused research on SAV in the areas  of




distribution and abundance, role and value, and  factors that may have caused



the decline of SAV (U.S. EPA Synthesis Report, 1982).  The research  phase  of



the Chesapeake Bay Program  was completed in 1983 and the implementation




phase is currently in progress.



     An early but important consideration in the distribution  aspects was




how to determine the abundance of SAV effectively on a baywide basis.




Aerial photography was chosen as the most cost effective and efficient




method of acquiring quantitative information.  In 1978 all the shallow  water




areas of the bay were flown with medium scale photography (scale 1:24,000).




This mapping study resulted in the publication of a series of  topographic



                                   -1-

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quadrangles depicting the  presence  of SAV beds  throughout the Chesapeake Bay
region (Orth,  et al.,  1979;  Anderson and Macomber, 1980).  During subsequent
years, selected areas of the bay  were photographed and/or mapped for SAV but
no complete baywide survey has  been conducted since 1978.
     Between 1978 and 1984,  field surveys in different sections of the bay
or rivers were conducted by the U.S. Geological Survey (USGS), Maryland
Department of  Natural Resources (Md.DNR), Northern Virginia Community
College (NVCC) and the Virginia Institute of Marine Science (VIMS), to
monitor the presence and/or absence of SAV  in these particular areas.  In
addition, researchers at the Harford Conmunity  College and the University of
Maryland's Horn Point Laboratories  (UMdHPL) had been monitoring SAV
populations in their respective study areas.  Studies in the Choptank River
by the UMdHPL  have shown a decline  in SAV since 1980.  However, some surveys
found SAV to be increasing in distribution  and  abundance in certain
sections, especially in the Potomac River and Susquehanna Flats.  Surveys
first by the USGS and then by NVCC  showed not only increases  in natural
species such as wild celery (Vailisneria americana) and sago  pondweed
(Potamogeton pectinatus) but also significant populations of  two species
never previously recorded in this area, water stargrass  (Heteranthera dubia)
and Hydrilla (Hydrilla verticillata).  The  latter species was of particular
concern because of its potential  rapid growth rate and its ability to spread
and outcompete more desirable species of SAV.
     During 1984, SAV beds in the bay were  photographed and mapped under
grants by the  USEPA and the National Oceanographic and Atmospheric
Administration (NOAA) to VIMS and EPA's Environmental Photographic
Interpretation Center (EPIC).  In addition, ground surveys for SAV were
conducted in the Potomac River by the USGS  and  NVCC and  in the entire
                                   -2-

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Maryland section of the bay by Md.DNR.   This report draws upon not  only



information provided by the aerial photography but also data from the




surveys conducted in the Potomac River  (Allaire,  et al.,  1985; Carter,  et




al., 1985a; Rybicki, et al.,  1985) and  the multi-station survey conducted



annually by the Md.DNR.  Field observations made  in the Susquehanna River




and Flats (Stan Kollar, personal communication) and the Choptank River




(Robert Twilley, personal communication) were used to corroborate and fill




in areas missed by the aerial photography.  Unlike the 1978  studies,  this




represents a unique effort to combine all the information into one  baywide




report of the 1964 sl.atus of SAV.
                                  -3-

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                                SECTION 2



                               SAV SPECIES




     Ten species of submerged vegetation are  abundant in the bay.  Zostera




marina (eelgrass) is dominant in the  lower reaches.  Myriophyllum spicatum




(water milfoil), Potamogeton pectinatus (sago  pondweed), P_. perfoliatus




(redhead grass), Zannichelia palustris  (horned pondweed), Vallisneria




americana (wild celery),  Elodea canadensis (common elodea), Ceratophyllum




demersum (coontail) and Najas quadalupensis (southern naiad) are less




tolerant of high salinities  and are found in  the middle and upper reaches of




the bay (Stevenson and Confer,  1978;  Orth, et  al., 1979; Orth and Moore,




1981 ,  1983).  Ruppia maritima (widgeongrass)  is tolerant of a wide range of



salinities and is found from the bay  mouth to the Susquehanna Flats.




Approximately ten other species are found less commonly and are present




primarily in the middle and  upper  reaches of  the bay and the rivers



(Appendix A).  One species presently  found in the Potomac River, Hydrilla




verticillata (Hydrilla),  has the potential for becoming one of the dominant




species found here (Allaire, et al.,  1985; Rybicki, et al., 1985).
                                  -4-

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                                 SECTION 3
Aerial Photography




     Aerial photography was the principal method used to assess  the



distribution of SAV in the Chesapeake Bay and its tributaries in the  1984




study.  Pre-determined flight lines for photography of areas  that either had




SAV or could  potentially have SAV (that is all  areas where water depths




were less than 2 m at mean low water) were drawn on 1:25,0000 scale USGS




maps to ensure both complete coverage of S/V beds and inclusion  of land




features as control points for mapping accuracy  (Fig. 1).   Some  areas  were




not included because of the known lack of SAV in those areas.




     The general guidelines used for mission planning and  execution are




given in Table 1.  These guidelines address tidal stage,  plant growth, sun




elevation, water transparency and atmospheric transparency, turbidity, wind,




sensor operation and plotting and allowed for acquisition  of  photographs




under near optimal conditions.  The guidelines are critical because




significant distortion of any one item could significantly decrease the




ability to detect the SAV or to interpret the photography  properly as  to the



presence or absence of SAV.



     The camera used for aerial photography of SAV in Virginia was a




Fairchild CA-8 cartographic camera with a 152 mm (6 1/2 inch) focal length




Bausch and Lomb Metrogon lens.  Film was Kodak 24 cm (9 1/2 inch) square



positive Aerochrome MS type 2448.   The camera was mounted  in  a camera  port




in the bottom fuselage of the VIMS single engine, fixed high  wing De




Havilland Beaver aircraft gelatine.  A wratten 1A haze filter was used




inside the cone of the camera to reduce the degrading effect  of  atmospheric




haze on image quality.  Flights were conducted at an altitude of



                                   -5-

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Figure 1.   Flight lines used for  acquisition of  aerial  photographs of SAV  in
           1984 for Virginia and  Maryland  (lines connecting gray squares
           represent flight  lines used  in  this survey).
                                  -6-

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KILOMETER

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TABLE 1.   GUIDELINES FOLLOWED DURING ACQUISITION OF AERIAL PHOTOGRAPHS.
1.  Tidal Stage - Photography was  acquired  at  low tide, +/- 0-1.5 ft., as
    predicted by the National Ocean Survey  tables.

2.  Plant Growth - Imagery was acquired when growth stages ensured maximum
    delineation of SAV,  and when phenologic stage overlap was greatest.

3.  Sun Angle - Photography was  acquired when  surface reflection from sun glint
    did not cover more than 30 percent  of frame.  Sun angle was generally
    between 20° and 40°  to minimize water surface glitter.  At least 60 percent
    line overlap and 20  percent  side lap was used to minimize image degradation
    due to sun glint.

4.  Turbidity - Photography was  acquired when  clarity of water ensured complete
    delineation of grass beds.

5.  Wind - Photography was acquired during  periods of no or low wind.  Off-shore
    winds were preferred over on-shore  winds when wind conditions could not be
    avoided.

6.  Atmospherics - Photography was acquired during periods of no or low haze
    and/or clouds below  aircraft.   There could be no more than scattered or thin
    broken clouds, or thin overcast above aircraft, to ensure maximum SAV to
    bottom contrast.

7.  Sensor Operation - Photography was  acquired in the vertical mode with less
    than 5 degrees tilt.   Scale/altitude/film/focal length combination permitted
    resolution and identification  of one square meter area of SAV (surface).

8.  Plotting - Each flight line  included sufficient identifiable land area to
    assure accurate plotting of  grass beds.
                                  -7-

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approximately 12,000 ft yielding a scale of  1:24,000  for the photograph,




approximating that of a standard U.S.  topographic  quadrangle.




     The SAV photography for the Maryland waters was  obtained by Aero Eco




under contract to the Bionetics Corporation  (onsite contractor for




EPA/EPIC).  The camera used by Aero Eco  was  a  Zeiss Jena LMK 15/2323 with a




153 mm (6.02 inch) focal length Zeiss  Jena Lamegon PI/C lens.  The film used




was Kodak 24 cm (9 1/2 inch) square positive Aerochrome MS  type 2448.  The




camera was mounted in the bottom fuselage of Aero  Eco's Partenavia P68




Observer, a twin engine high wing reconnaissance aircraft.  An




antivignetting filter was olso used.   The photography was also acquired at



an approximate altitude of 12,000 feet.




     Several problems were encountered during  the  acquisition of the 1984




aerial photography.  Weather patterns  consisting of high percentage of cloud




cover and haze appeared to be greater  than in  past years.   This effectively




reduced the time available to collect  the SAV  imagery.  Poor weather




conditions in certain restricted areas,  e.g.,  Dahlgren, Patuxent MAS or




around Smith Island, compounded the problem  since  access to the airspace



over these areas was limited to certain  hours  of each day or certain days




only.  Both camera and film processing malfunctions,  which  resulted in the



loss of all or portions of some of the flight  lines,  occurred in 1984, but,




where, possible, were supplemented with  similar aerial photography acquired




in 1983.  These problems are further addressed in  the next  section.




Mapping Process




     Fig. 2 gives the location of the  topographic  quadrangles in the study



area.  This area includes all regions  with a potential for  SAV growth.  The




quadrangles are sequentially numbered  to allow for more efficient access to



                                   -8-

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Figure 2.   Location of  topographic  quadrangles  in the Chesapeake Bay and
           tributaries  for  determining  distribution of SAV.
                                  —9—

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KILOMETER

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TABLE 2.  LIST OF USGS  7.5-MINUTE  QUADRANGLES IN CHESAPEAKE BAY
          SAV STUDY AREA AND  CORRESPONDING CODE NUMBERS (SEE FIG.
          2 FOR LOCATION OF QUADRANGLES.  THOSE TOPOGRAPHIC
          QUADRANGLES WITH SAV BEDS CAN BE FOUND IN APPENDIX B).
   1.  Conowingo Dam, Md.-Pa.         39
   2.  Aberdeen, Md.                  49
   3.  Havre de Grace, Md.            41 ^
   4.  North East, Md.                42.
   5.  Elkton, Md.                    43
   6.  White Marsh, Md.               44
   7 .  Edgewood, Md.                  45
   8.  Ferryman, Md.                  45
   9.  Spesutie, Md.                  47
  10.  Earleville, Md.                43.
  11.  Cecilton, Md.                  49
  12.  Baltimore East, Md.            59
  13.  Middle River, Md.              51
  14.  Gunpowder Neck, Md.            52
  15.  Hanesville, Md.                53 .
  16.  Betterton, Md.                 54
  17.  Galena, Md.                    55
  18.  Curtis Bay, Md.                55.
  19.  Sparrows Point, Md.            57m
  20.  Swan Point, Md.                53.
  21.  Rock Hall, Md.                 59.
  22.  Chestertown, Md.               60.
  23.  Round  Bay, Md.                 61.
  24.  Gibson Island, Md.             52.
  25.  Love Point, Md.                63.
  26.  Langford Creek, Md.            64
  27.  Centreville, Md.               65.
  28.  Washington West, Md.-DC-Va.    66
  29.  Washington East, DC-Md.        67
  30.  South  River, Md.               68
  31.  Annapolis, Md.                 69
  32.  Kent Island, Md.               79.
  33.  Queenstown, Md.                71m
  34.  Alexandria,  Va.-Md.            72
  35.  Deale, Md.                     73
  36.  Claiborne, Md.                 74.
  37.   St. Michaels,  Md.              75_
  38.  Easton,  Md.                    76.
Fort Belvoir, Va.-Md.
Mt. Vernon, Va.-Md.
Lower Marlboro, Md.
North Beach, Md.
Tilghman, Md.
Oxford, Md.
Trappe, Md.
Preston, Md.
Quantico, Va.-Md.
Indian Head, Va.-Md.
Benedict, Md.
Prince Frederick, Md.
Sharps Island, Md.
Church Creek, Md.
Cambridge, Md.
East New Market, Md.
Widewater, Va.-Md.
Nanjemoy, Md.
Mathias Point, Md.-Va.
Popes Creek, Md.
Mechanicsville, Md.
Broomes Island, Md.
Cove Point, Md.
Taylors Island, Md.
Golden Hill, Md.
Passapatanzy, Md.-Va.
King George, Va.-Md.
Dahlgren, Va.-Md.
Colonial Beach North,  Va.-Md,
Rock Point, Md.
Leonardtown, Md.
Hollywood, Md.
Solomons Island, Md.
Barren Island, Md.
Honga, Md.
Wingate, Md.
Nanticoke, Md.
Colonial Beach South,  Va.-Md,
                                      -10-
                                continued

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                      TABLE 2.  (continued)
  77.  Stratford Hall, Va.-Md.       118.
  78.  St. Clements Island, Va.-Md.  119.
  79.  Piney Point, Va. Md.          120.
  80.  St. Marys City, Md.           121.
  81.  Point No Point, Md.           122.
  82.  Richland Point, Md.           123.
  83.  Bloodsworth Island, Md.       124.
  84.  Deal Island, Md.              125.
  85.  Monie, Md.                    126.
  86.  Champlain, Va.                127.
  87.  Machodoc, Va.                 128.
  88.  Kinsale, Va.-Md.              129.
  89.  St. George Island, Va.-Md.    130.
  90.  Point Lookout, Md.            131.
  91.  Kedges Straits, Md.           132.
  92.  Terrapin Sand Point, Md.      133.
  93.  Marion, Md.                   134.
  94.  Mount Landing, Va.            135.
  95.  Tappahannock, Va.             136.
  96.  Lottsburg, Va.                137.
  97.  Heathsville, Va.-Md.          138.
  98.  Burgess, Va.-Md.              139.
  99.  Ewell, Va.-Md.                140.
100.  Great Fox Island, Va.-Md.     141.
101.  Crisfield, Va.-Md.            142.
102.  Saxis, Va.-Md.                143.
103.  Dunnsville, Va.               144.
104.  Morattico, Va.                 145.
105.  Lively, Va.                   146.
106.  Reedville, Va.                 147.
107.  Tangier Island, Va.           148.
108.  Chesconessex, Va.             149.
109.  Parks ley, Va.                 150.
110.  Urbanna, Va.                  151.
111.  Irvington, Va.                 152.
112.  Fleets  Bay, Va.               153.
113.  Nandua  Creek                  154.
114.  Pungoteague, Va.              155.
115.  West Point, Va.                156.
116.  Saluda,  Va.                   157.
117.  Wilton,  Va.
Deltaville, Va.
Jamesville, Va.
Toano, Va.
Gressitt, Va.
Ware Neck, Va.
Mathews, Va.
Franktown, Va.
We stover, Va.
Charles City, Va.
Brandon, Va.
Norge, Va.
Williamsburg, Va.
Clay Bank, Va.
Achilles, Va.
New Point Comfort, Va.
Cape Charles, Va.
Cheriton, Va.
Savedge, Va.
Claremont, Va.
Surry, Va.
Hog Island, Va.
Yorktown, Va.
Poquoson West, Va.
Poquoson East, Va.
Elliotts Creek,  Va.
Townsend, Va.
Bacons Castle, Va.
Mulberry Island, Va.
Newport News North, Va,
Hampton, Va.
Benns Church, Va.
Newport News South, Va
Norfolk North, Va.
Little Creek, Va.
Cape Henry, Va.
Chuckatuck, Va.
Bowers Hill, Va.
Norfolk South, Va.
Kempsville, Va.
Princess Anne, Va.
                                      -11-

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the data.  Table 2 gives the corresponding names  of  the  157  quadrangles



shown in Fig. 2.




     SAV beds were identified on the photographs  using all available




information, including knowledge of aquatic grass signatures on  the film,




areas of grass coverage from previous flights,  ground information, and




aerial visual surveys.  Mylar topographic  quadrangles (1:2*1,000) were used




in the mapping process.  Delineation of  SAV bed boundaries was facilitated




by superimposing on a light table the appropriate mylar  quadrangle with  the




transparent photograph.  SAV boundaries  were delineated  on the mylar map




with a pencil.  Where minor scale differences were evident between the




photograph and quadrangle or where significant  shoreline erosion or




accretion had occurred since production  of the  map,  a best fit was obtained,




or shoreline changes were noted on the quadrangle.   Areas of SAV beds were




derived from the 1 :24,000 scale topographic quadrangle.   Measurements were




made on a Numonics Graphics Calculator,  model 1224 for the lower bay.  EPIC




utilized a Calma Graphic Interactive Image Analysis  System based on a Data



General Eclipse S230 minicomputer for upper bay areas.   Each SAV bed was




digitized three times and the area reported as  the average of the three.



Each of the three measurements was generally within  5% of the mean.



     In addition to the boundaries of the  SAV bed, an estimate of percent




cover within each bed was made visually  in comparison with an enlarged Crown




Density Scale, similar to those developed  for estimating of  forest tree




crown cover from aerial photography (Fig.  3)-  Bed density was classified




into one of four categories based on a subjective comparison with the




density scale.  These were:  1. very sparse;  <105&, 2. sparse, 10 to M0%; 3-




moderate, 40 to 70%; or 4. dense, 70-100?.  Either the entire bed, or sub-




sections within the bed, were assigned a number (1 to 4) corresponding to





                                   -12-

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Figure 3-   Crown density  scale  used  for  determining density of SAV beds:
           very sparse  (1), 0-10$; sparse  (2), 10-40$; moderate (3), ^0-70?;
           dense (H), 70-100*.
                                  -13-

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the above density categories.   In addition to the density scale, each




distinct SAV unit was given a  letter  designation for proper identification



for future comparisons.




     In order to reduce  interobserver variability in both the mapping and



digitizing process,  steps were taken  to  insure  quality assurance.  Sections



from several areas in both Maryland and  Virginia containing SAV were




independently mapped and assigned a density  classification.  Results were




compared for compatability of  mapping effort.   In addition, mapped sections




were independently digitized for  similar comparisons.




     The discussion  of the distribution  of SAV  has been organized into three




zones as established by  Orth and  Moore (198?).  The area between the mouth




of the bay to a line stretching from  the mouth  of the Potomac River at Smith




Point in Virginia to just above Smith Island and extending across to the




north shore at the mouth of the Big Annemessex  River is referred to as the




Lower Bay zone (Fig. 4).   The  area between the  north shore of the Big



Annemessex River and the south shore  of  the  Potomac River to the Chesapeake




Bay bridge at Kent Island is referred to as  the Middle Bay zone.  The area



between the Chesapeake Bay bridge and the Susquehanna Flats is referred to



as the Upper Bay zone.  The salinity within each zone roughly coincides




with the major salinity  zones  of  estuaries;  polyhaline (18-25 /oo), Lower




zone; mesohaline (5~18 /oo), Middle zone; oligohaline (0.5-5 /oo), Upper




zone.  Although the  major rivers  and  smaller tributaries of the bay have




their own salinity regimes, the distributions of SAV in each river are




discussed within the zone where it connects  to  the bay proper.




     In addition, twenty one major sections  of  the bay are identified for




more detailed discussion of SAV distribution (Orth and Moore, 1982) (Fig. U,




Table 3).  These sections denote  relatively  distinct parts of the bay that



                                  -14-

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Figure ty.   Location of  upper,  middle  and  lower  zones  of  the Chesapeake Bay
           and the 21 major sections  used for delineation  of SAV
           distribution patterns  (see Table  3 and  text for exact
           boundaries).
                                  -15-

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-------
TABLE 3.  AREA DESCRIPTION  FOR EACH  OF 21 MAJOR SECTIONS IN THE CHESAPEAKE
          BAY HAVING SAV.
Section 1.  Susquehanna Flats  -  all  areas between and including Spesutie
            Island and Turkey  Point  at  the mouth of the Elk River to include
            the Northeast River.

Section 2.  Upper Eastern Shore  -  all areas in the Elk, Bohemia and Sassafras
            Rivers and SAV in  areas  on  the eastern shore above the Swan Point
            quadrangle.

Section 3-  Upper Western Shore  -  all areas south of Spesutie Island and
            north of the bay bridge  to  include the Bush, Gunpowder, Middle,
            Patapsco and Magothy Rivers.

Section 4.  Chester River - includes all of the Chester riiver, Eastern Neck,
            areas north of the bay bridge on Kent Island and south of Swan
            Point but to include SAV on the Swan Pt. quadrangle.

Section 5.  Central Western Shore  -  all areas south of the bay bridge and
            north of Holland Point on Herring Bay to include the Severn,
            South and West Rivers  and Herring Bay.

Section 6.  Eastern Bay - all  areas  south of the bay bridge on Kent Island
            and north of Tilghman  Island from Green Marsh Point to include
            the Wye, East and  Miles  Rivers, Crab Alley Bay, Prospect Bay and
            Poplar, Jefferson  and  Coaches Islands.

Section 7.  Choptank River - all areas  south of Tilghman Island from Green
            Marsh Point and north  of Taylor Island to include the Choptank
            and Little Rivers.

Section 8.  Patuxent River - all areas  in the Patuxent River.

Section 9.  Middle Western Shore - all  areas south of Holland Point at
            Herring Bay and north  of Point Lookout on the Potomac River but
            not the mouth of the Patuxent River.

Section 10.  Lower Potomac River  -  all areas between the mouth of the Potomac
            River to just above  the  301 bridge at Nanjemoy Creek.

Section 11.  Upper Potomac River  -  all areas above Nanjemoy Creek to
            Washington D.C.

Section 12.  Middle Eastern Shore - all  areas south of Taylor Island and north
            of but not including the Big Annemessex River to include the
            Honga, Nanticoke,  Wicomico  and Manokin Rivers, Fishing Bay,
            Bloodsworth and South  Marsh Islands.
                                  -16-
                                  continued

-------
                            TABLE  3.   (continued)
Section 13-  Tangier Island Complex  -  all areas south of and including the Big
             Annemessex River  and north of but including the northern shore
             of Chesconessex Creek  to include Smith and Tangier Islands,
             Little Anemessex  River and Pocomoke Sound.

Section 1^.  Lower Eastern Shore  - all  areas south of but including the
            southern shore of  Chesconessex Creek and north of Elliots Creek
            to include Cherrystone  Inlet, Hungars, Nassawadox, Occohannock,
            Nandua, Pungoteague  and Onancock Creeks.

Section 15.  Reedville - includes the  area between Windmill Point on the
            Rappahannock River and  Smith Point at the mouth of the
            Potomac River.

Section 16.  Rappahannock River Complex - includes the entire Rappahannock
            River,  Piankatank  River and Milford Haven area.

Section 17.  New Point Comfort  Region  - includes the area fronting the bay
            from the lighthouse  at  New Point Comfort north to, but not
            including, the bay entrance to Milford Haven.

Section 18.  Mobjack Bay Complex  - includes the East, North, Ware and Severn
            Rivers, the north  shore of the Mobjack Bay from New Pt. Comfort
            lighthouse to the  North River, and the area around Guinea Neck to
            include all the SAV  around the Guinea Marsh area from the New
            Point Comfort quadrangle.

Section 19.  York River - all areas  along the north shore from Clay Bank
            to the Guinea Marsh  area  and includes SAV from the Achilles
            quadrangle facing  the York River and along the south shore to
            Goodwin Island.

Section 20.  Lower Western Shore  - includes all areas south of Goodwin Island
            to Broad Bay off Lynnhaven Inlet, excluding the James River.

Section 21 .  James River - all  SAV in  the James River including the
            Chickahominy River.
                                  -17-

-------
are readily identifiable from  a map.  Sections 1 through 4 are located in




the Upper Bay zone.   Sections  5 through 12 are located in the Middle Bay




zone, and sections  13 tnrough  21 are located in the Lower Bay zone.  One •




additional section  was added to the original 20 sections denoted by Orth and




Moore (1982) to account for a  resurgence of SAV in the tidal freshwater and



transition zone of  the Potomac River.  This section had little SAV in 1978.




     Orth, et al. (1979) chose six sites in the Lower Bay zone to determine




changes in SAV distribution starting in 1937.  These sites are Mumfort




Island and Jenkins  Neck in the York River, East River in the Mobjack Bay,




Parrott Island in the Rappahannock River, Fleets Bay located between



Windmill Point on the Rappahannock River and Smith Point on the Potomac




River and Vaucluse  Shores located on the bayside of the eastern shore just



above Cape Charles  (see Orth,  et al. (1979) for further details of these




historical sites).   Detailed mapping of each historical site was completed




in this study similar to the earlier work to provide a 1984 update.




     For those areas currently known to contain some SAV where aerial




photography could not be obtained in 1984 the quadrangles were noted and



determination of SAV abundance from that area was made utilizing low level




aerial reconnaissance, aerial  photography of these areas in 1983 or 1984



from other sources,  anecdotal  information or other field surveys indicating




the presence of SAV  in 1981.   In these particular situations, distribution




of SAV will be assumed to match what was found in 1978.




Ground Truth and Other Data Bases




     For those areas in Virginia where aerial photographic evidence of SAV




beds was inconclusive, photoverification was accomplished by ground truthing



these sites.  This  was done principally by small boats and divers snorkeling




over the area indicated from the photograph.  Since SAV beds in this region





                                  -18-

-------
contain primarily only one or two species  that  vary little from year to
year, a great deal of ground truth information  could  be extrapolated from
earlier studies (Orth, et al.,  1979,  1982;  Orth and Moore, 1982).
     In Maryland, ground truth data were provided  principally from three SAV
surveys conducted in 1984,  from an SAV  transplanting  project and an ongoing
SAV research project.  Two field surveys were conducted in the Potomac
River.  The first survey was conducted  along the transition zone by the
NVCC (Allaire, et al., 1985).   The area covered consisted of 150 miles of
shoreline from Quantico Creek and Chicamuxen Creek in the north to the 301
bridge in the south (Fig. 5).   The second  survey was  conducted by the USGS
(Carter, et al.,  1985a;  Rybicki, et al., 1985)  and included the area from
the Chain Bridge at Washington, D.C.  to the Wicomico  River just below the
301 bridge (Fig.  6).  Earlier surveys of the Potomac  River by the USGS
included sections of the river south  of the Wicomico  River to the mouth of
the Potomac River (Carter,  et al.,  I985b;  Haramis  and Carter, 1983).
Methods used in these two surveys were  similar:  either sampling along pre
determined transects or marked grids  using modified oyster tongs to estimate
species presence and their standing crop.   Visual  observations were also
used for species  identification.  Additional information of these surveys is
available in the above-mentioned reports.
     The third survey is the annual large  scale multi-station survey
conducted by the Md.DNR.  This survey,  conducted from June through August,
samples 600+ randomly selected stations in certain areas of the bay from the
Susquehanna Flats to Smith Island.  At  each station,  samples are also
collected with modified oyster tongs  and species presence or absence, as
well as standing crop, recorded.
                                  -19-

-------
Figure 5.   Location diagram  and  USLS  1 :24,000 quadrangle index for NVCC
           Potomac River SAV  shoreline study.  Numbers under quadrangle name
           indicate number of vegetated  grids and the total number of grids
           located in that quadrangle (from Allaire, et al., 1985).
                                  -20-

-------

-------
Figure 6.   Location of vegetation sampling transects  in  the  tidal  and
           transition portion of the Potomac River  used  by the U.  S.
           Geological Survey for determining SAV  distribution patterns  (from
           Carter, et al.,  1985a).
                                   -21-

-------

-------
     The SAV transplanting project  is  being  conducted on the Susquehanna



Flats by Stan Kollar of Harford Community College.   Information provided by




his work is in the form of species  presence  by  percentage, primarily by




visual estimates.




     An SAV research group at  UMdHPL headed  by  Mike  Kemp also provided




ground truth data.  Robert Twilley  of  their  group  annotated maps of their




six study sites on the Choptank River,  indicating  status of SAV from 1980 to



1984 at each site.  No information  on  percent cover  was available.




     In addition to 1984 collateral data, a  visual aerial  survey of the




Susquehanna River, the Northeast River and the  upper Bush  River was




conducted in 1982  by Dr. Richard Anderson, under contract  to Martin



Marietta.  SAV data were annotated  onto USGS 7.5~minute quadrangles from low




level (300-500 feet) observations.   Species  information was provided, but no




percent cover values were obtained.
                                  -22-

-------
                                 SECTION 4




                           RESULTS  AND DISCUSSION




     The results of the 1984  SAV  aerial and ground surveys of the entire bay




and its tributaries showed the  presence of extensive stands of vegetation in




a number of locations throughout  the  bay as well as the continued absence of




SAV beds in areas where they  were once abundant.




     Table 4 presents hectares  of SAV for those quadrangles where vegetation




was observed in 1984 and 1978.  Table 5 presents the total hectares of SAV




for each of the 21  sections and the 3 zones for both 1984 and 1978.   Table 6




presents the total square meters  of SAV in those topographic quadrangles




found in each of the 21  sections.   Table 7 presents the square meters of SAV




in each of the four density classes (1-4) for those quadrangles having SAV




only.




     Given the constraints of the 1984 data set (see methods and succeeding




sections where problems occurred),  it was estimated that there were 15,400




hectares of SAV in 1984 compared  to 16,637 found in 1978.  Increases of SAV




were observed in the following  sections:  Susquehanna Flats, Upper Eastern




Shore, Upper Potomac River, Tangier Island Complex, Lower Eastern Shore, New




Point Comfort, Lower Western  Shore  and York River.  Decreases were observed




in the Upper Western Shore, Chester River, Central Western Shore, Eastern




Bay, Choptank River, Patuxent River,  Middle Western Shore, Lower Potomac




River, Middle Eastern Shore,  Reedville, Rappahannock River, Mobjack Bay and




James River sections.  The Lower  Bay  zone showed an ]Q% increase in SAV




abundance from 1978 to 1984 with  9400 hectares mapped in 1978 and 11,116




hectares mapped in 1984.   The Middle  Bay zone showed a reduction in SAV of




11% in this time period (4,446  to 984 hectares) while SAV in the Upper Bay




zone increased 13$ (792 to 3168 hectares).





                                  -23-

-------
TABLE 4.   TOTAL AREA  OF SAV  IN  HECTARES BY TOPOGRAPHIC QUADRANGLES FOR 1978
          AND 1984.
         QUANDRANGLE

  1.  Conowingo Dam,  Md.-Pa.
  2.  Aberdeen, Md.
  3.  Havre de Grace, Md.
  4.  North East,  Md.
  5.  Elkton, Md.
  6.  White Marsh, Md.
  7.  Edgewood, Md.
  8.  Ferryman, Md.
  9.  Spesutie, Md.
 10.  Earleville,  Md.
 11.  Cecilton, Md.
 12.  Baltimore East, Md.
 13.  Middle River,  Md.
 14.  Gunpowder Neck, Md.
 15.  Hanesville,  Md.
 16.  Betterton, Md.
 17.  Galena, Md.
 18.  Curtis Bay,  Md.
 19.  Sparrows Pt.,  Md.
 20.  Swan Point,  Md.
 21.  Rock Hall, Md.
 22.  Chestertown, Md.
 23.  Round Bay, Md.
 21.  Gibson Island,  Md.
 25.  Love Point,  Md.
 26.  Langford Creek,
 27.  Centreville, Md
 28.  Washington West
 29.  Washington East
 30.  South River, Md.
 31.  Annapolis, Md.
 32.  Kent Island, Md.
 33.  Queenstown,  Md.
 34.  Alexandria,  Va.-Md.
 35.  Deale, Md.
 36.  Claiborne, Md.
 37.  St. Michaels,  Md.
 38.  Easton, Md.
 39.  Fort Belvoir,  Va.-Md.
 40.  Mt. Vernon,  Va.-Md.
 41.  Lower Marlboro, Md.
 42.  North Beach, Md.
Md.
 Md.-DC-Va.
 DC-Md.
                        1978
                       803.67
                         5.62
                           .75

                        10.48

                           .84
                         4.67
  90
 200
   9
   6
   1
  33
  10
  29
 127
  12
 137
 139
  11
1255
  38
,06
.71
• 31
,40
,46
.40
,52
.86
,25
.31
,15
.45
.81
.20
.75
                         15.
                         27.
                        513-
                        492.

                         61.
                        421 ,
                        366.
                          1,
     14
     15
     68
     10

     51
    ,08
     09
    ,19
                    1984
   0
1741.85
  13.31
   0
   0
  49.8H
   2.01
 411.38
   3-47
   0
   0
   0
 183.99^
                                              5.
                                              5.
    .48
    .74
  11.88
   0
   0
  18.65
  30.13
   0
   0
   7.61
   0
 599.72
   0
   0 + +
   0
   0
   0
  26.28
  89.45
 160.40
   0
  52.25
  11.14
   0
    .91
 420.34
   0
   0
                                 continued

                                  -24-

-------
TABLE 4.  (continued)

13.
41.
15.
16.
17.
18.
19.
50.
51.
52.
53.
51.
55.
56.
57.
58.
59.
60.
61 .
62.
63.
61.
65.
66.
67.
68.
69.
70.
71.
72.
73-
71.
75.
76.
77.
78.
79.
80.
81.
82.
83.
81.
85.
86.
87.
88.


Tilghraan, Md.
Oxford, Md.
Trappe, Md.
Preston, Md.
Quantico, Va.-Md.
Indian Head, Va.-Md.
Benedict, Md.
Prince Frederick, Md.
Sharps Island, Md.
Church Creek, Md.
Cambridge, Md.
East New Market, Md.
Widewater, Va.-Md.
Nanjemoy, Md.
Machias Pt. , Md.-Va.
Popes Creek, Md.
Mechanicsville , Md.
Broomes Island, Md.
Cove Pt. , Md.
Taylors Island, Md.
Golden Hill, Md.
Passapatanzy , Md.-Va.
King George, Va.-Md.
Dahlgren, Va.-Md.
Colonial Beach North, Va.-Md.
Rock Pt., Md.
Leonardtown, Md.
Hollywood, Md.
Solomons Island, Md.
Barren Island, Md.
Honga, Md.
Wingate, Md.
Nanticoke, Md.
Colonial Beach South, Va.-Md.
Stratford Hall, Va.-Md.
St. Clements Island, Va.-Md.
Piney Point, Va.-Md.
St. Marys City, Md.
Point -No-Point, Md.
Richland Pt. , Md.
Bloodsworth Island, Md.
Deal Island, Md.
Monie, Md.
Champlain, Va.
Machodoc, Va.
Kinsale, Va.-Md.
continued
-25-
178.15
562.96
61.75
-
-
-
1.58
-
377.08
208.91
18.96
-
-
28.03
191.12
-
13.62
1.91
2.97
-
-
-
2.25
8.32
87.11
22.85
2.11
-
10.51
-
126.91
2.64
-
61.95
5.53
.13
-
-
-
.73
66.07
3.01
9.15
-
-
~~


6.87
23.25
0
0
0
0-n-
0
0
1.12
9.00
0
0
1.59
30.92
121.11
0
0
4.37
3.75
8.55
.12
0
13.11
2.67
25.63
0
0
0
.76
0
5.05
8.81
0
11.26
2.16
0
-
-
-
.38
18.29
0
0
-
-
™



-------
TABLE 1.  (continued)

89.
90.
91.
92.
93.
91.
95.
96.
97.
98.
99.
100.
101 .
102.
103.
101.
105.
106.
107.
108.
109.
110.
111.
112.
113.
111.
115.
116.
117.
118.
119.
120.
121 .
122.
123.
121.
125.
126.
127.
128.
129.
130.
131.
132.
133.
131.


St. George Island, Va.-Md.
Point Lookout , Md.
Kedges Straits, Md.
Terrapin Sand Point, Md.
Marion, Md.
Mount Landing, Va.
Tappahannock, Va.
Lottsburg, Va.
Heaths ville, Va.-Md.
Burgess, Va.-Md.
Ewell, Va.-Md.
Great Fox Island, Va.-Md.
Crisfield, Va.-Md.
Saxis, Va.-Md.
Dunnsville, Va.
Morattico, Va.
Lively, Va.
Reedville, Va.
Tangier Island, Va.
Chesconessex, Va.
Parksley, Va.
Urbanna, Va.
Irvington, Va.
Fleets Bay, Va.
Nandua Creek, Va.
Pungoteague, Va.
West Point, Va.
Saluda, Va.
Wilton, Va.
Deltaville, Va.
Jamesville, Va.
Toano, Va.
Gressitt, Va.
Ware Neck, Va.
Mathews, Va.
Franktown, Va.
Westover, Va.
Charles City, Va.
Brandon, Va.
Norge, Va.
Williamsburg, Va.
Clay Bank, Va.
Achilles, Va.
New Point Comfort, Va.
Cape Charles, Va.
Cheriton, Va.
continued
-26-
_
-
156.09
311.18
289.33
-
-
-
-
-
1183.30
510.65
7.18
-
-
-
-
230.10
105.06
182.51
80.35
—
5.31
133.23
181.86
101 .63
—
-
10.13
59.13
106.01
—
—
256.00
63.88
501.19
—
—
-
16.18
—
—
797.92
1096.31
321.12
85.20


_,
-
366.12
187.00
0
-
-
-
—
-
2308.58
807.81
113.01
-
-
-
—
108.56
611.11
808.61
261.80
—
9.33
155.15
315.10
716.76
—
—
0
6.62
367.36
—
—
203.15
30.32
395.26
•"•
—
—
16.18**
~
—
711.50
1092.71
308.32
55.99



-------
                          TABLE 4.  (continued)
135.   Savedge,  Va.
136.   Claremont,  Va.
137.   Surry,  Va.
138.   Hog Island, Va.
139.   Yorktown, Va.                             1.92                0.23
140.   Poquoson  West, Va.                      210.44              216.93
141.   Poquoson  East, Va.                      516.63              687.16
142.   Elliots Creek, Va.                       44.58               14.48
143.   Townsend, Va.                            42.70                4.80
144.   Bacons  Castle, Va.
145.   Mulberry  Island, Va.
146.   Newport News North, Va.
147.   Hampton,  Va.                            218.25              233.15
148.   Benns Church, Va.
149.   Newport News South, Va.                   1.87                0
150.   Norfolk North, Va.
151.   Little  Creek, Va.                         -                   0
152.   Cape Henry, Va.                           *                  37.87
153.   Chuckatuck, Va.
154.   Bowers  Hill, Va.
155.   Norfolk South, Va.
156.   Kempsville, Va.
157.   Princess  Anne, Va.                   	-              	-
      TOTAL                               16,636.39           15,399.70
NOTES:  -  indicates  quadrangle not photographed and assumed to have  no SAV
        0  indicates  quadrangle photographed and no SAV noted
        *  area not flown in  1978 but most likely had SAV in 1978 based on
           data collected in  subsequent years
       **  area not photographed in 1984.  Area known to still have SAV.  We
           made the assumption that the 1984 distribution would be similar
           to the  1978 distribution.
        +  Information on SAV distribution taken from 1983 aerial
           photographs provided by Willie Burton of Martin Marietta Corp.
       ++  Presence of SAV beds not detected from 1984 aerial photography.
           Information provided by Virginia Carter of the USGS for the 1984
           Potomac River Shoreline Survey indicated presence of SAV.
                                  -27-

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TABLE 5.   NUMBERS  OF  HECTARES  OF BOTTOM COVERED WITH SUBMERGED AQUATIC
          VEGETATION  IN 1978 AND 1984 FOR DIFFERENT SECTIONS WITHIN THE THREE
          ZONES IN THE  CHESAPEAKE BAY  (DATA FOR 1978 FROM ORTH, et al., 1979 AND
          ANDERSON AND  MACOMBER, 1980.
Section
1. Susquehanna Flats
2. Upper Eastern Shore
3. Upper Western Shore
4. Chester River
5. Central Western Shore
6. Eastern Bay
7. Choptank River
8. Patuxent River
9. Middle Western Shore
10. Lower Potomac River
11. Upper Potomac River
12. Middle Eastern Shore
13. Tangier Island Complex
14. Lower Eastern Shore
15. Reedville
16. Rappahannock River Complex
17. New Point Comfort Region
18. Mobjack Bay Complex
19. York River
20. Lower Western Shore
21 . James River
TOTAL
1978
Hectares Zone
804 +
29 Upper
484 2792
1475 hectares
241
1800
1740 Middle
34 4446
11 hectares
410
0*
210
3759
1991
364
93 Lower
271 9399
1785 hectares
157
925
54
16,637
1984
Hectares Zone
2150
43 Upper
244 3168
731 hectares
0
66
82 Middle
9 984
0 he ct ar es
194
600
33
5447
2232
264
23 Lower
299 11,248
1550 hectares
238
1149
46
15,400
+ 1978 data for Susquehanna Flats remapped and digitized to allow for greater
 compatability to 1984  data.

*No aerial photography  was taken of  this area in  1978 and that the absence of
 SAV is based on ground survey observations by the USGS.
                                    -28-

-------
TABLE 6.   NUMBER OF SQUARE  METERS  OF  SAV  IN EACH  QUADRANGLE CONTAINED WITHIN
          THE 21  SECTIONS FOR 1981
SECTION
Susquehanna Flats - 1
Upper Eastern Shore - 2
Upper Western Shore - 3
QUADRANGLE
              (1)
Conowingo Dam
Aberdeen (2)
Havre de Grace (3)
North East (4)
Ferryman (8)
Spesutie (9)
North East (4)
Elkton (5)
Ferryman (8)
Spesutie (9)
Earleville (10)
Cecilton (11)
Gunpowder Neck
Hanesville (15)
Betterton (16)
Galena (17)
Swan Point (20)
Rock Hall (21 )
White Marsh (6)
Edgewood (7)
Ferryman (8)
Spesutie (9)
Baltimore East (12)
Middle River (13)
Gunpowder Neck (14)
Hanesville (15)
Curtis Bay (18)
Sparrows Point (19)
Round Bay (23)
Gibson Island (24)
   AREA

         0
         0
17,418,496
         0
         0
 4,082.974

21,501,470 sq.m =
2150.1 5 hectares
5310.86 acres

   133,146
         0
         0
    22,526
    34,703
         0
         0
    54,798
    57,422
   118,828
         0
    10,002
                     431,425 sq.m =
                      43.14 hectares
                     106.56 acres

                              0
                        498,100
                         20,136
                          8,325
                              0
                              0
                      1,839,900
                              0
                              0
                              0
                              0
                         76,075
                                                        2,442,536 sq.m =
                                                          244.25 hectares
                                                          603.31 acres
                                  -29-
                                 continued

-------
                          TABLE 6.   (continued)
Chester River - 4
Central Western Shore - 5
Eastern Bay - 6
Choptank River - 7
Swan Point (20)
Rock Hall (21)
Chestertown (22)
Love Point (25)
Langford Creek  (26)
Centreville (27)
Kent Island (32)
Queenstown (33)
Round Bay (23)
Gibson Island (24)
South River (30)
Annapolis (31)
Deale (35)
North Beach (42)
Love Point (25)
Annapolis (3D
Kent Island (32)
Queenstown (33)
Claiborne (36)
St. Michaels (37)
Easton (38)
Claiborne (36)
St. Michaels  (37)
Easton (38)
Tilghman  (43)
Oxford (44)
Trappe (45)
Preston (46)
Sharps Island (51 )
Church Creek  (52)
Cambridge (53)
East New Market  (54)
Taylors Island  (62)
  186,456
  291,300
        0
        0
5,997,246
        0
   77,356
  756,388

7,308,746 sq.m -
  730.87 hectares
 1805.25 acres

        0
        0
        0
        0
        0
        0
        0

        0
        0
  185,439
  138,088
  222,031
  111,365
        0
  656,923 sq.m -
   65.69 hectares
  162.25 acres

  300,482
        0
        0
   68,699
  232,542
        0
        0
   44,176
   90,017
        0
        0
   85,512
                                                          821 ,428 sq.m =
                                                            82.1 4 hectares
                                                          202.89 acres
                                  -30-
                                 continued

-------
                           TABLE  6.   (continued)
Patuxent River - 8
Middle Western Shore - 9
Lower Potomac River - 10
Lower Marlboro (41)
Benedict (49)
Mechanicsville (59)
Broomes Island (60)
Cove Point (61)
Hollywood (70)
Solomons Island (71)
North Beach (42)
Prince Frederick  (50)
Broomes Island (60)
Cove Point (61)
Solomons Island  (71)
St. Marys City (80)
Point No Point (81 )
Point Lookout (90)
Nanjemoy (56)
Mathias Point  (57)
Popes Creek (58)
Dahlgren (66)
Colonial Beach
  North (67)
Rock Point (68)
Leonardtown (69)
Colonial Beach
  South (76)
Stratford Hall (77)
St. Clements
  Island (78)
Piney Point (79)
St. Marys City (80)
Machodoc (87)
Kinsale (88)
St. George
  Island (89)
Point Lookout  (90)
Lottsburg (96)
Heathsville (97)
Burgess (98)
       0
       0
       0
   43,692
   37,518
       0
   7,616

   88,826 sq.m =
    8.88 hectares
   21.93 acres

       0
       0
       0
       0
       0
      np
      np
      n£
       0

   309,243
 1,211,162
        0
   26,712

   256,316
        0
        0

   112,561
   21 ,600

        0
       np
       np
        0
        0

       np
       np
       np
       np
	np
                                                        1 ,937,594 sq.m =
                                                          193.76 hectares
                                                          478.59 acres
                                  -31-
                                 continued

-------
                          TABLE 6.   (continued)
Upper Potomac River -  11
Middle Eastern Shore - 12
Tangier Island Complex - 13
Washington West (28)
Washington East (29)
Alexandria (3*0
Fort Belvoir (39)
Mt. Vernon (10)
Quantico (17)
Indian Head (48)
Widewater (55)
Passapatanzy (61)
King George (65)
Taylors Island (62)
Golden Hill (63)
Barren Island (72)
Honga (73)
Wingate (71)
Nanticoke (75)
Richland Point (82)
Bloodsworth
  Island  (83)
Deal Island (81)
Monie (85)
Kedges Straits (91)
Terrapin Sand
  Point (92)
Marion (93)
        0
        0
1 ,603,981
    9,072
1,203,106
        0
        0
   15,861
        0
  131.113

5,996,736 sq.m =
  599.67 hectares
 1181.19 acres

        0
    1,218
        0
   50,178
   88,116
        0
    3,810

  182,910
        0
        0
        0

        0
        0
Chesconessex (108)    7
Parksley (109)        2
Tangier Island (107)  6
Ewell  (99)           23
Great  Fox IslandOOO) 8
Kedges Straits (91)   3
Terrapin Sand
   Point (92)         1
Crisfield (101)       1
Marion (93)
Saxis  (102)
  329,592 sq.m =
   32.96 hectares
   81 .11 acres

  ,816,191
  ,618,039
  ,111,118
  ,085,831
  ,078,128
  ,661,153

  ,869,981
  ,130,088
         0
         0
                                  -32-
                                                        51,167,135  sq.m =
                                                         5,116.71 hectares
                                                        13,153.37 acres
                                 continued

-------
                           TABLE  6.   (continued)
Lower Eastern Shore - 14
Elliots Creek (142)
Townsend (143)
Cape Charles (1 33)
Cheriton (131)
Franktown (124)
Jamesville (119)
Nandua Creek (113)
Pungoteague (114)
Chesconessex (108)
   144,822
    48,042
 3,083,185
   559,874
 3,952,565
 3,673,577
 3,451,033
 7,167,565
   239,628

22,320,291  sq.m =
2,232.03 hectares
5,513.11 acres
Re.;dville - 15
Fleets Bay (112)
Reedville (106)
Burgess (98)
 1,554,487
 1 ,085,642
	0

 2,640,129 sq.m =
 264.01  hectares=
 652.10 acres
Rappahannock River Complex - 16
New Point Comfort Region - 17
Mathews (123)
Wilton (117)
Deltaville (118)
Irvington (111)
Urbanna (110)
Champlain (86)
Mount Landing (94)
Tappahannock (95)
Dunnsville (1 03)
Morattico (104)
Lively (105)
Saluda (116)
Mathews (123)
New Point
  Comfort (132)
    72,588
         0
    66,241
    93,276
         0
         0
         0
         0
         0
         0
         0
         0
                                                          232,105 sq.m =
                                                          23.21  hectares
                                                          57.33  acres
                                                         2,985,042

                                                         2,985,042 sq.m =
                                                         298.50  hectares
                                                         737.30  acres
                                   -33-
                                 continued

-------
                          TABLE 6.   (continued)
Mobjack Bay Complex - 18
 Achilles (13D
 New Point
    Comfort (132)
 Ware Neck (112)
 Mathews (123)
 5,297,298

 7,342,019
 2,031 ,^75
   230.562

15,501 ,354 sq.m -
 1 ,550.14 hectares
 3,828.82 acres
York River - 19
 Poquoson West (140)
 Yorktown (139)
 Clay Bank (130)
 Achilles (131 )
 West Point (115)
 Toano  (1?0)
 Gressitt (121)
 Williamsburg  (129)
   257,028
     2,340
         0
 2,117,660
         0
         0
         0
	0

 2,377,046 sq.m -
   237.70 hectares
   587.1 2 acres
Lower Western Shore - 20
 Cape Henry (152)
 Hampton  (147)
 Poquoson East (141)
 Poquoson West (140)
 Norfolk North (150)
 Little Creek  (151 )
 Kempsville (156)
 Princess Anne (157)
   378,
   ,331,
   ,871,
   ,912,
714
495
628
278
  0
  0
  0
  0
                                                        11 ,494,115 sq.m =
                                                        1,149.41 hectares
                                                        2,839.04 acres
James River - 21
  Hampton  (147)                 0
  Newport  News
    South  (149)                 0
  Norge  (128)             464,766
  Savedge  (135)                 0
  Claremont  (136)               0
  Surry  (135)                   0
  Hog Island (138)              0
  Yorktown (139)                0
  Bacons Castle  (144)           0
  Mulberry Island  (145)         0

 -34-
continued

-------
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-------
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-------
     In order to facilitate the  discussion of the distribution of SAV in the



bay, each of the 21  sections in  the  3 major  zones will be discussed




separately.




                           1.  SUSQUEHANNA FLATS




     The distribution of SAV in  this section for 1984 was based primarily on




species presence and abundance from  Dr. Stan Kollar because of the loss of




imagery of the Flats area.   SAV  beds on the  Flats for 1978 were remapped to




allow for greater comparability  to the 1984  data.  Instead of mapping each




small bed, the entire area was remapped as distinct units and given a




density classification.   Thus, instead of 110 hectares being reported on




1978, the remapping of these data yielded 804 hectares in a density 1




classification.  In 1984, the Flats  contained sparse patches of SAV




throughout the region which were mapped as one  unit and then classified as a



density of 1 (very sparse).  Thus, the 1984  survey showed 2,150 hectares in




this section compared to 804 in  1978 (Tables 4-7).  The information provided




by Kollar indicates a large increase, albeit only in small patches on the




Susquehanna Flats, from  1978 to  1984.  Seven species of SAV were found in




1984, with milfoil, the  most abundant, being found in patches throughout the




Flats.  Wild celery was  the second most important species in this section.




Both species were noted  in 1978  with milfoil also being the most common.




Both Hydrilla and water  stargrass were noted in 1984 in small isolated




pockets but not in 1978.




     The Md.DNR survey sampled 37 stations in 1984 and found no vegetation



in any of these stations (Table  8, Fig. 7).  No stations were located in the




Susquehanna River where  SAV occurs along the shoreline just north of the




Interstate 95 bridge.  The survey did find some vegetation from 1981 to 1983






                                  -39-

-------



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-40-

-------
Figure 7.   Trends of occurrence of  submerged  vegetation  at  eight of the 26
           areas surveyed by  the Maryland Department  of  Natural Resources,
           1971-1984.
                                  -41-

-------
                                 cc
                                 <
SNOI1V1S JO  lN3083d

-------
but the very sparse nature of SAV  on  the Flats probably resulted in the SAV




not being sampled in 1984.




     It appears from the SAV  survey conducted in 1982 by Dr. Richard




Anderson, ground observations by Stan Kollar in 1984 and the 1984 aerial




survey, that SAV is expanding both in the Susquehanna River and the Flats.




                          2.  UPPER EASTERN SHORE




     Small, scattered SAV beds  were found in this section in the Elk and



Sassafras Rivers in 1984.   A total of 43 hectares were mapped in 1984




compared to 29 hectares in 1978 (Tables 4-7) with 30% of the SAV found in




the Elk River of the North East quadrangle.  Seven of the 12 quadrangles had




SAV in 1984 compared to 8 in  1978.  The small beds found in the Elkton and




Swan Point quadrangles in 1978  were not observed in 1984 while the SAV beds




in the North East quadrangle  in 1984  were not present in 1978.   Fifteen




stations were sampled in the Elk and  Bohemia Rivers by the Md.DNR in 1984




with no vegetation recorded at  any of the stations (Table 8).  Several of




the stations were located in  deep  water just off SAV beds evident on the




photography.  SAV was found in  one of ten stations in the Sassafras River by



this survey.  The SAV was milfoil  and was noted to be abundant throughout



Lloyd Creek where SAV had been  observed in the photographs in 1978.  Five



stations on Stillpond had no SAV in the Md.DNR survey although SAV was




observed on the aerial photography in 1984 and 1978 in this area on both the



Hanesville and Betterton quadrangles.  Seven additional stations were




sampled in the Howell and Swan  Point  system and no SAV were found.
                                  -42-

-------
                          3.   UPPER  WESTERN SHORE




     The 1978 aerial survey indicated there were 484 hectares of SAV.  In




1984, several flight lines were lost here due to a malfunction in the film




processing.  As a consequence,  SAV beds  for 1984 were poorly represented in




the Middle, Gunpowder and Bush Rivers where large beds were found in 1978.




However, aerial photography of  the Gunpowder River was available for 1983




from Martin Marietta which showed SAV beds in areas similar to 1978.  Thus,




SAV information for 1984  was  assumed to  be similar to 1983.  The Middle




River was not flown in 1983 and it could be assumed there was SAV in this




river similar to the 1978 distribution.  Th? available 1983-84 photography




showed 244 hectares of SAV in this section.  Thus, the distribution of SAV




in 1984 shown here is probably less  than what was actually present.




     The Md.DNR survey showed vegetation at 3 of 27 stations in the




Gunpowder, Bush, Back and Middle Rivers  (Table 8).  The three stations that




had SAV were in the Middle River and contained wild celery, milfoil and




Chara sp.  In the Magothy River, two of  12 stations had SAV (only horned




pondweed) while no SAV was found in  23 stations in the Patapsco River.




                             4.   CHESTER RIVFR




     In 1978, the Chester River section  contained a diverse assemblage of 7




species of SAV encompassing 1,475 hectares.  These species included milfoil,




redhead grass, wild celery, horned pondweed, widgeongrass and Naiad species.




Eighty-five percent of the SAV  in 1978 was in the Langford quadrangle with




the grasses occurring along both shorelines of the lower Chester River.  In




1984, 731 hectares of SAV were recorded  with 82% found in the Chester River,




Langford quadrangle.  There was a decrease of 655 hectares in the Langford




quadrangle from 1978 to 1984.   No SAV was mapped for the East and West Forks




of Langford Creek in 1984 because of a film processing malfunction.  There



                                  -43-

-------
were 97 hectares found in this  area  in  1978.  There were SAV beds in this




area in 1984, as the Md.DNR survey recorded redhead grass, milfoil and sago



pondweed.




     The Md.DNR survey found 19.4$ of their 35 stations in the Chester River



vegetated in 1984 compared to 1 %  in  1983 and 0% in 1982 (Table 8, Fig. 7).



However, this was still lower than the  44J of the stations vegetated in the




1978 photo survey.   Notes taken during  the 1984 Md.DNR survey indicated




large beds of SAV inshore from  many  of  the actual sampling stations as well




as much drift SAV.




                         5.   CENTRAL WESTERN SHORE




     No SAV's were noted in this  section in 1984, compared with 241  hectares




found in 1978 (Tables 4-7).   Aerial  coverage of this section in 1984 was




complete.   Fifty-seven percent  of the vegetation in 1978 in this section was




present in the Severn River  with  smaller amounts found in the South and




Rhode Rivers.  Seven species were present:  milfoil, wild celery, redhead




grass, sago pondweed, horned pondweed,  widgeongrass and Najas sp.



     The Md.DNR survey found no SAV  in  1984 in the Severn, South, West and




Rhode River systems (Table 8).   Twenty-seven percent of the stations in the



Severn River were vegetated in  1978.  This declined to 0% in 1982.  Some



vegetation was found in 1983 but  declined to 0% again in 1984.  Since 1971




the Md.DNR survey has never found SAV in the South-West-Rhode Rivers.



                             6.  EASTERN BAY




     In 1984, only 66 hectares  of SAV were noted in the aerial photography




for the section.  This was a significant decrease from the 1,800 hectares of




SAV recorded in 1978, which was the  most abundant section that year (Tables




4-7).  Diverse beds of milfoil,  redhead grass, sago pondweed, elodea, horned




                                  -44-

-------
pondweed and widgeongrass were found  along the shores of Eastern Bay in 1978




but these were considerably reduced by  1984.




     The Md.DNR found no vegetation at  8 stations in the Love-Kent Points




systems and SAV at only 3 of 46 stations in the Eastern Bay system in 1984




(Table 8).  In 1978,  26.1$ of the  stations were vegetated.  This percentage




has vacillated between 1978 and 1984, increasing to 34.8$ in 1980 and then




declining to the 6.5$ in 1984.   The only species found by the survey in 1984




was widgeongrass.




                             7.  CHOPTANK RIVER




     In 1984, only 82 hectares of  SAV were noted in the aerial photography




compared with 1740 hectares in 1978.  Five species were observed in 1978:




milfoil, sago pondweed, redhead grass,  common elodea and horned pondweed.




Large decreases of SAV were noted  from  1978 to 1984 in the Claiborne,




Oxford, Sharps Island and Church Creek  quadrangles.  In 1984, 65$ of the SAV




was found in two quadrangles, Claiborne and Oxford.




     The Md.DNR survey found SAV in only 1 of 60 sampled stations in the




Choptank River and no SAV in 19 stations in the Little Choptank River (Table




8).  The only species found in 1984 was widgeongrass.  In 1978, 28.3$ of the




stations in the Choptank River were vegetated which declined to lower levels




after 1980.   No vegetation has been found in the Little Choptank River since




1979.   The qualitative surveys of  the UMdHPL found SAV at only 2 of their 6




monitoring stations in 1984.   In 1980,  the year they began monitoring all




six stations were  vegetated.  .The  most  dramatic loss of SAV occurred at




Benoni Point (Oxford  quadrangle),  Dickinson Bay (Trappe quadrangle), and




Todd's Cove (Church Creek quadrangle) during the 1981-82 growing season.
                                  -45-

-------
                             8.   PATUXENT RIVER




     In 1984,  9 hectares  of SAV were observed from the photography, compared




with 31* hectares in 1978  (Tables  4-7).  SAV occurred in the Broomes Island,




Cove Point and Solomons Island  quadrangles in 1984.  Two species,




widgeongrass and horned pondweed,  were  found in 1978.  The Md.DNR survey




found no SAV in 43 stations and have not recorded any since 1979 when 2% of




the stations were vegetated,  the  same percentage as 1978 (Table 8).




                          9.  MIDDLE WESTERN SHORE




     No SAV was recorded  in this  section in 1984 compared to 11 hectares




found in 1978 (Tables 4-7).   The  Md.DNR survey found no SAV in 8 sampled




stations in Curtis - Cove Points  system (Table 8).  This area is a very




exposed region and would  not  be expected to support significant stands of




SAV.




                          10.   LOWER POTOMAC RIVER




     The Potomac River received more coverage, both from ground and aerial




surveys, than any other part  of the bay.  Ground surveys by the Md.DNR,




NVCC, and USGS and the 1984 aerial survey provided excellent coverage of the




Distribution of SAV's this year.   However, several problems were encountered




with the aerial survey.   Five quadrangles were not covered with photography




because of airspace restrictions  by the Patuxent NAS:  Piney Point, St.




Marys City, Point No Point, St. George  Island and Point Lookout.  The 1978




aerial survey found no SAV's  in these quadrangles.  However, Carter, et al




(1985) did find three or  four species growing in the St. Marys River during




their 1978-81  survey.  Another  complication was the timing of the flights




for the Potomac River in  1984.  Very  poor atmospheric conditions delayed the




flying of the Potomac River  flight lines until early November when some of
                                  -46-

-------
the SAV had decline  .   This resulted  in less coverage than that expected




during the growing  eason.




     In 1984,  the .  rial  survey  noted 194 hectares of SAV compared to 410




hectares found in '  78 (Tables 4-7).  SAV was found in the Nanjemoy, Mathias




Point, Dahlgren,  C<  onial Beach  North, Colonial Beach South and Stratford




Hall quadrangles  it  1984, similar  to  what was observed in 1978.  Most of the




SAV in 1984 was in  he Mathias Point  quadrangle (63?) as was the case in




1978 (48*).




     The Md.DNR sut  -ey sampled 88  stations  in the lower section and found




vegetation in only  ne, near Blossom  Point  at the mouth of Nanjemoy Creek.




Wild celery and wi  ;eongrass were  the only  two species observed.




     The USGS samp  d only  the freshwater tidal and transition zone down to




the Wicomico River  in 1983 and  1984)  (Fig. 6).  Table 9 lists the species




found in the  vege'  ited transects.  Wild celery, milfoil, redhead grass,




sago pondweed, and  idgeongrass  were  among  the species found in this




section.   A compar.  on with earlier data collected from 1978-1981 indicated




more vegetated sta'  ons and grabs  were found on sampled transects in 1984




than in 1981 (Tabl<  10).



     The NVCC surv<  • also sampled  in  the transition zone (Fig. 5) in 1984



and found 9 specie  in this section (Table  11).  These were the same species




found by the USGS .  irvey.  The distribution of the species found by NVCC is




given in Figs. 8-1    Wild  celery  was by far the most abundant species found




by the NVCC survey  md often was found in 100? coverage.




     It is apparen  from  the data  collected by the USGS and NVCC that SAV




was more abundant >  lan indicated in the aerial survey.  Thus, the smaller




amount of SAV foun  in 1984 is most probably due to the timing of the aerial





                                  -47-

-------
TABLE 9.   SPECIES  OF SUBMERSED AQUATIC PLANTS FOUND ON VEGETATED TRANSECTS
          IN THE TIDAL POTOMAC RIVER AND TRANSITION ZONE,  1984.

                         n.d. is no data available
  Transect
   Spring
                                         Species
                                                I/
    Fall
   OR-1R

   AD-1R
   DM-1R
   DM-2R
   DM-3R

   DM-HR
   GC-1R

   GC-2R
   GC-14R
   WC-1R
   BC-1T-1
   PY-1R
   PY-1.5R
   PY-2R
   PY-3R

   PY-4R
   PY-5R
   PY-7R
   PY-8R
   PY-1T-1
   PY-1T-3
   PY-2T-1
   MN-9R
   MN-10R
Hydr,  Vail,
P. pect,  Zann
Hydr,  P.  cris
Hydr
Hydr
Hydr

Hydr,  P.  pect
Vail,  Zann

Cerat
Vail, Zann
Cerat, Heter,
Hydr, Myrio,
Najas g.,  P.  cris
P. pect, Vail
Myrio, Naj as  m.
Myrio, Najas  m.
Myrio
Vail, Zann
Cerat
Hydr
Cerat, P. pect
P. pect, Vail,
Zann
Heter

Hydr
Cerat, Hydr
Cerat, Hydr
Cerat, Hydr,
Nitella
Cerat, Heter,
Hydr, Myrio,
Nitella, Vail
Heter, Hydr,
Myrio
Myrio, Vail
Vail
Vail
n.d.
Myrio
n.d.
Cerat, Heter,
Hydr, Myrio,
Najas g., Vail
Hydr, Myrio
Najas g.
Najas g.
Heter
Heter, Hydr,
Myrio, Najas g.,
Najas m., Vail
Cerat, Heter,
Hydr, Myrio
Najas g., Vail,
Zann
Myrio,
n.d.
Cerat, Hydr, Myrio
Vail
Vail
                                  -48-
                                 continued

-------
                           TABLE 9.   (continued)
  Transect
                                          Species
                                                 1 /
Spring
Fall
MN-14T-1
MN-14T-2

MP-3R
MP-4R

NP-2R
NP-3R
NP--HR
NP-5K
NP-bR

NP-7R
NP-8R
NP-9R
NP-10R

NP-11R
NY-3T-3

PO-1T-5
PO-2T-1
PO-2T-2
PO-2T-3
PO-3T-1
WO-5T-1
WD-8T-1
Cerat
Vail

Vail
Myrio, Najas g.,
Vail, Zann
n.d.
n.d.
n.d.
n.d.
n.d.

n.d.
n.d.
n.d.
n.d.

n.d.
n.d.

n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Cerat, Myrio
Najas g., P. pus,
Vail
n.d.
n.d.

Vail
Vail
P. perf, Vail
Vail
Cerat, P. pect ,
P. perf, Vail
Vail
Vail
P. perf, Vail
Myrio, P. perf,
Vail
Vail
Cerat, Myrio,
P. pus
Myrio, Vail
Vail
Vail
Vail
Myrio, Vail
P. perf, Rupp
Najas g. , Rupp

1_/Cerat = Ceratophyllum demersum,  Heter =  Heteranthera dubia,
  Hydr = Hydrilla verticillata,  Myrio = Myriophyllum spicatum,
  Najas g = Najas guadalupensis,  Najas m = Najas  minor
  Nitella = Nitella flexilis,  P.  cris = Potamogeton crispus,
  P.  pect = Potamogeton pectinatus,  P.  pus =  Potamogeton  pusillus,
  Vail = Vallisneria americana,  Zann = Zannichellia palustris
  P.  perf = Potamogeton perfoliatus, Rupp  = Ruppia maritima
                                  -49-

-------
TABLE 10.   RELATIVE  OCCURRENCE OF VEGETATED TRANSECTS, STATIONS AND GRABS FOR
           THE  TIDAL POTOMAC  RIVER AND ESTUARY, 1978-81 AND 1984.
            Relative  occurrence as  number vegetated/total number
Site
Tidal river
Washington
Channel
transects
stations
grabs
Mattawoman/
Piscataway
Creeks
transects
stations
grabs
Gunston
Cove
transects
stations
grabs
Transition
Maryland
Point

transects
stations
grabs
Wicomico
River
transects
stations
grabs
Vegetated
Date

Fall 1981

1/1
2/4
6/12
Summer 1978


1/34
1 /160
3/480
Fall 1979

0/13
0/65
0/195
zone
Spring 1981


2/4
5/20
8/60
Summer 1981

2/8
3/39
6/117
transects
Date

Fall 1984

1/1
3/4
7/12
Fall 1984


12/34
46/197
84/491
Fall 1984

3/13
14/77
17/231

Spring 1984


2/4
20/38
39/11 4
Fall 1984

2/8
9/44
24/132
Site Vegetated
Date

Pomonkey Spring 1981
Creek
0/4
0/20
0/60
MN-4T-2 Fall 1981


1/1
3/4
7/12






*Nanjemoy/ Summer 1981
Port Tobacco
River
17/17
53/108
1 19/324





transects
Date

Fall 1984

0/4
0/20
0/60
Fall 1984


1/1
1/5
3/15






Fall 1984


16/17
76/135
173/405





*0nly transects which had three  or more species in 1978-80 were sampled.
                                    -50-

-------









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-51-

-------
Figure 8.   Distribution  of  wild celery  (1), Vallisneria americana, in the
           trnsition zone of  the Potomac River, 1984 (from Allaire, et al.,
           1985).
                                  -52-

-------

-------
Figure 9.   Distribution of  Hydrilla  (1) Hydrilla verticillata, coontail (2)
           Ceratophyllum demersum, and milfoil  (3) Myriophyllum spicatum in
           the transition zone  of  the Potomac River, 1984  (from Allaire, et
           al.,  1985).
                                  -53-

-------

-------
Figure 10.   Distribution of sago pondweed (1)  £.  pectinatus,  curly pondweed
            (2)  P_.  crispua and redhead gras  (3) £.  perfoliatus  in the
            transition zone of the Potomac River,  198H  (from Allaire, et
            al., 1985).
                                   -54-

-------

-------
Figure 11.   Distribution of  widgeongrass  (1) Ruppia maritima, horned
            pondweed (2)  Zannichelia  palustris, Chara  (3) sp., and common
            elodea (4)  Elodea  canadensis  in the transition zone of the
            Potomac River, 1984  (from Allaire, et al., 1985).
                                  -55-

-------

-------
overflights in this area which were conducted after the peak in standing



crop of SAV.




                          11.   UPPER POTOMAC RIVER




     This section may be one of the most  interesting of this study because




of its past history and what has been occurring with SAV in the last three



years.  This section of the river had been largely devoid of SAV since the




1930's although large beds of  SAV were present in the early 1900's (Orth and




Moore, 1984; Carter, et al.,  1985b).   During the 1978-81 USGS surveys no




species of SAV were found.  Since 1981, however, not only has there been a




dramatic increase in many of the native species, but also three species,




Hydrilla verticillata,  Heteranthera dubia, and Najas minor, not present in




earlier surveys (Carter, et al.,  1985a,b) were reported.  This increase has




occurred in the reach between  Alexandria, Virginia, and Marshall Hall,




Maryland.   Fig. 12 shows the species  diversity of SAV in the tidal Potomac




River in 1983 while Fig. 13 shows the increase in species diversity in this




same area in 1984.  Comparison of the 1984 transect data (Table 9, Fig. 6)




with that of the 1978-81  survey clearly shows the increase in the upper




tidal river (Table 10).   All of the increase which occurred in the



Mattawoman/Piscataway Creeks and the  Gunston Cove regions was above Marshall



Hall.   There is still virtually no SAV  in the reach between Marshall Hall




and Quantico, Virginia.



     The presence of Hydrilla  is notable given the growth potential of this




species.  Hydrilla is a fast growing  exotic plant from Southeast Asia.  It




is considered a nuisance in California, Florida and other southeastern




states because it forms thick  mats of vegetation which interfere with




recreational use of the water.   It reproduces both vegetatively and




sexually,  and overwinters by tubers and turions.  In 1981 ,  a small



                                  -56-

-------
Figure 12.   SAV species  diversity  in  the  tidal Potomac River, 1983 (from
            Carter,  et  al.,  1985a).
                                  -57-

-------
                 77° 15'
                                                   717°
39°
45'
                                                EXPLANATION
                                                Number of species
                                                                10 MILES
                                                                 I
                                                       10 KILOMETERS

-------
Figure 13.   SAV species diversity in the  tidal  Potomac  River,  1984  (from
            Carter,  et al.,  1985a).
                                  -58-

-------
                  77«|l5'
7|7"
39°
_38°
45'
                                                  MARYLAND
                                                  EXPLANATION
                                                  Number of species
                  Mallows Bay
                                                     0

                                                     1-2
           3-4

           >4
              10 MILES
               I
                                                          I
                                                         10 KILOMETERS

-------
population of Hydrilla was  found  in Dyke Marsh, Virginia.  In 1982,  the

Department of Agriculture made  a  positive identification and discovered that

Hydrilla was widespread in  lentic environments in the Washington, D.C.  area.

By 1983, Hydrilla was firmly  established in the reach above Marshall Hall,

with its greatest population  in the Dyke Marsh area on the Virginia side of

the river (Fig.  14).   In 1984,  it filled in along the Maryland and Virginia

shorelines,  with the  largest  populations along the shoreline adjacent  to

and across from  Dyke  Marsh  (Fig.  15).   In many parts of the tidal river, it

is found growing with many  other  species and composes less than 10 percent

of the total plant material.  There is  concern that Hydrilla might

outcompete other desirable  SAV  species  in the Potomac River.

     Allaire et  al. (1985)  also reported Hydrilla in this section (Table 11)

but much farther south than that  reported by Rybicki et al. (1985).   It was

prevalent in the marsh guts on  the Maryland side of the river down to

Mathias Point and present in  1 3 of the  186 grids sampled (Fig. 9).  One

specimen was found floating in  a  tributary of Potomac Creek, and three

plants were found rooted behind the marsh at Aquapo Beach on Aquia Creek.

No Hydrilla was  found rooted  in the main part of the Potomac River in the

transition zone.

     Allaire et  al. (1985)  also found other species present in this section

(Table 11, Figs. 8-11).   No vegetation  was found in the Quantico quadrangle

while Indian Head, Widewater, Passapatanzy and King George had 20%,  2Q%, 32%

and 12? of the grids  vegetated, respectively.  Coontail and wild celery were

the most abundant species evident.

     The Md.DNR  survey sampled  52 stations in this section in 1984 and found

vegetation in only one,  Broad Creek.  Hydrilla was present in the three

samples collected from this site.
                                 -59-

-------
                   77"h5'
39°
45'
                                                    EXPLANATION
                                                    Percent Cover
                                                         10-40

                                                         <5 (occasional patches)
                                                                       10 MILES
                                                                        I
                                                             10 KILOMETERS

-------
     The 1984 aerial survey confirmed the  presence  of  the SAV beds in this




section (Tables 1-7) with 631  hectares mapped from  the photography.  Of the




11 quadrangles in this section,  SAV was present  in  six, with 67% found in




the Mt. Vernon quadrangle and  25? in the Alexandria quadrangle.  As




indicated from the ground surveys of the USGS, the  SAV was a mixture of many




species, including Hydrilla.   No SAV was mapped  for this section in 1978.




     The cause for the increase  in SAV in  this section is not known but may




be related to nutrient changes in this region.   There  has been a dramatic




decrease in phosphate loading  from the Blue  Plains  sewage treatment plant




since the late 1970's.  In 1983,  Blue Plains began  nitrification, changing




the predominant nitrogen species in the river from  ammonia to nitrate.  At




the same time, Blue Plains reduced the suspended solids output from the




plant (Table 12).   Secchi depths in the upper tidal river were significantly




higher in 1983 than in the 1978-81  (Table  13).   There  were blue-green algae




blooms during the summer of 1983  and 1981, but the  1983 bloom did not reach




the Wilson Bridge until nearly September,  moving upriver from the Quantico




area.  In 1981, the river discharge was higher and  the bloom never reached




the upper tidal river.  These  recent algal blooms have thus had little




effect upon the water clarity  and light available for  SAV growth in this




section.




                         12.   MIDDLE EASTERN SHORE




     In 1981, there was only 32.9 hectares of SAV in this section compared




to 210 hectares found in 1978  (Tables 1-7).   The earlier aerial survey found




only four species present:   widgeongrass,  horned pondweed, sago pondweed and




eelgrass.   This section comprises a large  area of the  mid-bay section with




many areas having large, broad flats (Bloodsworth and  South Marsh Islands)




or coves that would be conducive  for SAV growth,  yet very little is present



                                  -62-

-------
TABLE 12.   TOTAL SUSPENDED SOLIDS OUTPUT FROM THE PRIMARY OUTLET OF BLUE
           PLAINS SEWAGE  TREATMENT PLANT, 1982 AND 1983.


Month
April
May
June
July
August
September
October
[Monthly mean in mg/L (number
1982
9.8 (30)
1.16 (3D
7.09 (30)
U.82 (31 )
5.18 (3D
6.7 (30)
5.24 (3D
of observations)]
1983
1.2 (20)
1.0 (3D
1.3 (30)
1.1 (30)
1.2 (3D
1.2 (30)
1.3 (3D
                                  -63-

-------
TABLE 13.   SECCHI  DEPTH  IN THE UPPER AND LOWER TIDAL RIVER,  JULY-OCTOBER,
           1978-81  AND JULY-OCTOBER, 1983 (SE = STANDARD £RROR,  N = NUMBER OF
           OBSERVATIONS).

[Depth in cm]
Location/Date
Upper tidal river
July-October, 1978-81
July-October, 1983
July-August, 1983
Lower tidal river
July-October, 1978-81
July-October, 1983
July-August, 1983
Mean

51.8
85.5
87.3

38.8
50.8
50.8
SE

3.28
4.69
5.20

1 .29
4.96
4.96
N

38
48
39

72
13
13

                                  -64-

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today in this section.   Fifty-five  percent of the SAV in this section in

1984 occurs in the Bloodsworth quadrangle with the remaining beds located in

Golden Hill,  Honga,  Wingate  and Richlend Point quadrangles.   No SAV occurs

in 8 quadrangles.

     The Md.DNR survey  sampled 169  stations in this section, examining sites

in the James-Barren Island system,  Honga River, Fishing Bay, Nanticoke -

Wicomico River, Manokin River  and Big Annemessex River (Table 8, Fig. 7).

Only 1  of 15  stations in the Manokin River had SAV (widgeongrass) ,  while 1

of 12 stations in  the Big Annemessex River was also vegetated with

widgeongrass  (Table 8,  Fig.  7).  All the stations sampled in the other areas

were unvegetated.

                        13.  TANGIER ISLAND COMPLEX

     This section  contains the second largest number of quadrangles that

contain SAV (8) and is  the section  with the most SAV present.  In 1984,

5,376 hectares were mapped compared to 3,759 hectares in 1978, a 43$

increase (Tables 4-7).   The  number  of hectares in this section was  over

twice as much as in the next largest section, the Lower Eastern Shore, which

has 2,232 hectares.   Of the  SAV mapped in the Lower Bay zone, 48? is located

in the Tangier Island Complex.

     The SAV  beds  are concentrated  in several distinct areas:  adjacent to

Big Marsh between  Chesconessex Creek and Deep Creek, on the west side of

Webb and Halfmoon  Island,  the  east  side of Fox Islands around Cedar Straits

and the areas in and around  Tangier and Smith Islands and the large broad

shoal area between the  two islands.  Seventy-three percent (3,909 hectares)

of the SAV in this section is  located in the Tangier-Smith Island region.

This, by far, is the section of the bay that has the densest concentration

of SAV.
                                 -65-

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     The Md.DNR survey of Smith Island indicated a decline in SAV from 1983




to 1984, when only 29.4? of  the 17 stations were vegetated.   This is in




contrast to the photographic data showing a large increase in the Smith




Island area.   A comparison of  the 17 DNR station locations and the




distribution maps from aerial  photography indicated that the twelve




unvegetated stations  were adjacent to existing beds outlined in the




photographs and that  the five  vegetated stations were in areas classified as




dense from the photography.




     Two other areas  were field checked by the Maryland survey.  No SAV  was




found in the 22 stations in  the Pocomoke Sound area although small.




scattered beds were aerially mapped very close to the shoreline, well




inshore of the sampled stations.  In the Little Annemessex River, the




Maryland survey showed no SAV  in 8 sampled stations.  The aerial survey




showed beds located on both  shores of the river in a narrow band and well




inshore of several of the Maryland stations.  The SAV in the Crisfield




quadrangle increased  from 7  to 107 hectares from 1978 to 1984 in the aerial




survey while the Maryland survey has shown no increase and very little




vegetation in this region.




                         14.  LOWER EASTERN SHORE




     This section contains the largest number of quadrangles that contain




SAV (9) and is the second largest section in SAV area in the Lower Bay zone.




In 1984, 2,232 hectares, consisting of eelgrass and widgeongrass, were




mapped compared to 1,991 hectares in 1978, an increase of 12$ (Tables 4-7).




The largest beds were found  around Cape Charles at the mouth of Cherrystone




Inlet, and at the mouths of  Hungars and Mattawoman Creeks (also called




Vaucluse Shores), Occahannock  Creek, Craddock Creek, Pungoteague Creek and




Onancock Creek.  The  areas between these creek systems are sparsely



                                  -66-

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vegetated or unvegetated because of  the  exposed nature of these broad sand




flats.




     SAV in the Vaucluse Shores  historical  area  (includes part of Hungars




and Mattawoman Creeks)  (see Orth,  et al.,  1979, for a detailed description




of the site) has remained relatively stable since  1978 (Table 14, Fig. 16),




although changes prior  to 1978 were  a result  of the dynamic nature of the




sand bars and spits in  this region.   The historical area was also the site




where seven transects were made  in 1978  for species distribution.  These




transects showed widgeongrass  in the shallowest areas, eelgrass in the




deeper sites and both species  at intermediate depths.  Horned pondweed has




also been found mixed with widgeongrass  in  the shallowest depths.




                              15.   REEDVILLE




     In 1984, 264 hectares of  SAV  were observed in the section compared to




the 364 hectares mapped in 1978  (Tables  4-7).  Most of the beds, which are




found throughout the section,  were classified as sparse or very sparse




(Table 7).   This section contains  the Fleets  Bay historical site where 101




hectares were mapped in 1984 compared to 73 hectares in 1978 (Table 14, Fig.




16).   SAV coverage actually decreased from  1978 to 1980 but increased in




1981.  This increase from 1981 to 1984 was  noted to occur in areas that were




classified as sparse or very sparse.




                      16.   RAPPAHANNOCK  RIVER COMPLEX




     Only 23 hectares of SAV were found  in  this section in 1984 compared to




93 in 1978 (Tables 4-7).  Several  small  but dense  beds are present in the




Milford Haven area, remnants of  the  dense beds present in the early 1970's.




The other beds are small and sparse, located  along the north shore of the




Rappahannock River.  No SAV was  observed in  the Piankatank River.  There




were no SAV beds in the Parrott  Island historical  area (Table 14, Fig. 16).



                                  -67-

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TABLE 14.   AREAS OF SAV AT HISTORICAL  MAPPING SITES (LOWER BAY ZONE) 1937~1984
Parrott Islands

Date
1937
1951
1960
1968
1974
1978
1980
1981
1984

<10$
0
394,797
411,306
92,064
0
0
0
0
0

10-40?
297,024
778,146
631,566
1 ,354,110
2,922
22,872
0
0
0
Area m2
40-70$
1,598,268
1 ,222,410
547,014
1 ,205,628
7,710
0
0
0
0

70-100$
0
1 ,158,384
1,947,372
124,374
0
0
0
0
0

Total
1 ,895,292
3,553,737
3,537,258
2,776,176
10,632
22,872
0
0
0
Fleets Bay

Date
1937
1953
1961
1969
1974
1978
1980
1981
1984

<10$
0
1 ,488,258
1 ,572,612
1,436,403
105,714
167,688
0
0
232,164

10-40$
1,385,424
597,354
1,330,140
1 ,938,660
1 ,624,884
528,918
121 ,890
683,250
730,680
Area m2
40-70$
548,076
591 ,018
1,643,892
1 ,592,170
1,325,040
33,592
26,040
9,816
33,318

70-100$
744,864
284,232
884,280
270,372
0
0
2,472
13,986
14,556

Total
2,678,364
2,960,862
5,430,924
5,237,605
3,055,638
730,198
150,402
707,052
1 ,010,718
Mumfort Islands

Date
1937
1953
1960
1971
1974
1978
1980
1981
1984



<10$
0
151 ,728
0
0
0
0
0
0
0



10-40$
495,060
699,252
258,210
685,536
127,488
0
0
0
0


Area m2
40-70$
397,368
106,356
1 ,880,238
1 ,088,976
23,826
0
0
0
0
-68-
continued

70-100$
23,832
1 ,461 ,846
0
0
0
0
0
0
0



Total
91 6,260
2,419,182
2,138,448
1 ,774,512
151,314
0
0
0
0



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TABLE 14.   (continued)

Jenkins- Neck

Date
1937
1953
1960
1971
1974
1978
1980
1981
1984

<10*
0
426,480
140,448
0
93,972
132,714
60,810
0
72,876

10-40$
1 ,180,200
647,112
794,178
278,586
303,804
299,760
191 ,605
0
289,388
Area mz
40-70*
820,612
717,180
639,012
2,350,380
1 ,599,228
671 ,616
690,968
763,194
563,268

70-100*
32,520
1 ,811 ,832
2,067,948
33,792
93,912
162,408
179,589
309,012
954,360

Total
2,033,332
3,602,604
3,641,586
2,662,758
2,090,916
1 ,266,498
1,122,972
1 ,072,206
1 ,879,892
East River

Date
1937
1953
1963
1971
1974
1978
1980
1981
1984

<10*
1 ,024,010
591 ,840
31,032
0
509,730
47,860
191 ,520
0
496,445

10-40*
809,770
1 ,158,490
1 ,916,530
2,007,460
348,820
515,000
451,351
96,174
739,836
Area m2
40-70?
1,357,790
1 ,394,740
2,3^0,480
2,253,080
1 ,955,130
1 ,864,850
808,842
1 ,183,542
' 706,736

70-100*
85,530
1 ,742,050
0
96,620
0
0
158,634
198,474
88,458

Total
3,277,100
4,887,120
4,288,042
4,357,160
2,81 3,680
2,427,710
1 ,610,347
1 ,478,190
2,031,475
Vaucluse Shores

Date
1938
1948
1955
1966
1972
1978
1980
1981
1984

<10*
0
506,706
1 ,938,258
452,940
286,554
187,728
359,551
327,786
0

10-40?
1 ,120,284
1 ,171 ,884
0
402,324
364,764
507,054
7,098
97,950
15,792
Area m2
40-70*
1 ,451 ,392
1 ,715,556
528,996
2,53^,178
2,515,740
80,872
697,842
355,344
1,137,882

70-100*
1 ,480,128
0
1 ,238,124
604,176
391 ,770
2,036,526
1,783,938
1 ,852,392
1 ,731 ,678

Total
4,051 ,804
3,994,146
3,705,378
3,993,618
3,558,828
2,812,180
2,848,429
2,633,472
2,885,352
    -69-

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Figure 16.   Trends  in areal  coverage of SAV at six intensively mapped areas
            in the  lower  Chesapeake Bay, 1937-1984.
                                  -70-

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S3dVlD3H

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                       17.   NEW POINT  COMFORT REGION




     Dense beds of SAV were found  in this section in 198*1 from New Point




Comfort Lighthouse to just  north of Horn Harbor (Tables 4-7).  Two hundred




ninety-nine hectares of SAV were mapped in  1984 compared to 271  hectares in




1978.  Prominent features of this  section are the distinct, unvegetated sand




bars found parallel to the  shoreline with SAV found in the troughs between




successive bars.




     Two transects were made in the area in 1978 for species distribution.




Both eelgrass and widgeongrass  were present, with widgeongrass in the




shallower depths a Long the  transect and eelgrass in the deeper zones.




                          18.   MOB JACK BAY  COMPLEX




     This section contains  one  of  the  largest amounts of SAV in the lower




Bay zone.  In 1984, 1,550 hectares were mapped compared to 1785 hectares in




1978 (Tables 4-7).  SAV beds, consisting of eelgrass and widgeongrass, are




present along the shorelines of the entire  Mobjack Bay and three of the four




tributaries:  Severn, Ware  and  North Rivers.  Little SAV is present in the




East River.   One of the largest and densest beds found along the western




shore of the lower bay is present  around the Guinea Marshes in the New Point




Comfort quadrangle.




     Four transects on the  Achilles quadrangle (Browns Bay and Ware Point)




and two in the New Point Comfort quadrangle (mouth of East River) were made




in 1978.  Data from these transects also showed widgeongrass in the




shallowest depths and eelgrass  predominantly in the deeper locations with




the two found together at intermediate depths.




     SAV in the East River  historical  area  (see Orth, et al., 1979, for a




detailed description of this site) decreased from 1978 to 1984,  but




examination of data collected in 1980  and 1981- showed SAV increasing 37%



                                  -71-

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from 1981  to 1984  (Table  14,  Fig.  16).  Observation of this area has shown




the increase also  occurring  from recruitment and growth of seedlings.




                              19.  YORK RIVER




     There were 238  hectares  of SAV mapped in 1984 compared to 157 hectares




in 1978, an increase of 52%  (Tables 4-7).  The major SAV beds, consisting of




eelgrass and widgeongrass, in this section are present on the north side of




lower York River in  the Achilles quadrangle.  There are no SAV beds above




Gloucester Point in  the Clay  Bank  quadrangle.  One small bed present in the




Yorktown quadrangle  in 1984 near Gloucester Point was transplanted to this




area in the fall of  1983  (Orth, unpublished data).  Monitoring of the lower




York River has shown these areas to be increasing as a result of seedling




recruitment from adjacent, upstream beds, followed by rapid growth of these




seedlings.




     There was still no SAV present in the Mumfort Island historical area




while SAV increased  48$ from  1978  in  the Jenkins Neck historical area (Table




14, Fig. 16) (see  Orth, et al., 1979, for a detailed description of the




sites).  The increase is  a result  of  seedling establishment and growth.




     Two additional  0.25-hectare beds were transplanted near Gloucester




Point in the Achilles quadrangle,  one in the fall of 1982 and the second in




the fall of 1983-  The 1982  planting  was done on 1.0 and 0.5 m centers using




eelgrass.   The bed has grown  almost into one unit in less than three years.




The 1983 eelgrass  planting was conducted on 2 m centers and the units have




not coalesced but  are still  present and growing very well.  The 0.25-hectare




plot in the Yorktown quadrangle was also planted on 2 m centers.




                         20.  LOWER  WESTERN SHORE




     The SAV in this section, consisting of eelgrass and widgeongrass, was




found in the Broad Bay area  off Lynnhaven River, Back River, Drum Island






                                  -72-

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Flats between Back and Poquoson Flats, Poquoson River and on the south side




of Goodwin Island.  There were 1,1*19  hectares of SAV mapped in 1984 compared




to 925 hectares in 1978 (Tables 4-7).  The SAV beds in the Broad Bay area




(37.87 hectares-Cape Henry quadrangle) were not mapped in 1978, although it




is most likely they were present that  year since subsequent surveys from




1980 through 1983 has shown the persistence of this vegetation.  The




distribution of vegetation in the Hampton and Poquoson West quadrangles




remained similar while there was a 33? increase in SAV (51 6 to 687 hectares)




in Poquoson East quadrangle.   This increase occurred on the Drum Island




Flats adjacent to existing beds of SAV that, have persisted since the early




1970's.  Most of the beds in this section have been classified as moderate




(40 to 70%) or dense (70 to 100?) (Table 7).




                              21 .  JAMES RIVER




     The small patches of SAV,  consisting of eelgrass, in the Hampton Roads




area present in 1978 had disappeared  by 1980 and were still absent in 1984




(Tables 4-7).  The remaining SAV beds  identified in 1978 were located in the




Norge quadrangle, and although this area was not photographed and mapped in




1984, an aerial reconnaissance survey  of the area in late 1984 indicated




that these beds were still present that appeared very similar to the 1978




distribution maps.  We have assumed here that the 1984 total would be




similiar to the 1978 total.  These beds occur as narrow fringing beds




located along the edge of the marsh channels at water depths of less than 1




meter.  The dominant species here are  coontail, several Naiad species and




common elodea (Orth, et al.,  1979).
                                  -73-

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                                SECTION 5




                         SUMMARY AND CONCLUSIONS




     The distribution of  beds  of submerged aquatic vegetation in the




Chesapeake Bay and tributaries in 1984 was examined using both aerial




photographic and ground surveys.  Aerial photographs were used to map SAV




bed outlines onto topographic  quadrangles while ground surveys provided both




photo verification of the SAV  beds and species identification.  To delineate




SAV beds on a baywide basis, the distribution of SAV was divided into three




major zones and 21  sections within the three zones.  The areas mapped were




displayed on 157 topographic quadrangles.  The quadrangles include all areas




with a potential for  SAV  growth in the bay region.  The distribution data




for 1984 were compared to data collected from a baywide survey conducted in




1978.




     In 1984, SAV was found occupying 15,400 hectares of bottom.  Of this




total, 18.7? of the beds  were  classified as very sparse (<10? coverage),




18.6% as sparse (10-40?), 27.3? as moderate (40-70?) and 35.5? as dense (70-




100?).  In 1984, 20.6? of the  SAV beds were located in the Upper Bay zone,




6.3? in the Middle Bay zone and 73.0? in the Lower Bay zone.  The coverage




of SAV in 1984 was less than the total found in 1978 (16,637 hectares).  In




the 1978 survey, 16.8? of the  vegetation was found in the Upper Bay zone,




26.7? in the Middle Bay zone and 56.5? in the Lower Bay zone.  Increases in




SAV coverage from 1978 to 1984 were  measured in 8 of the 21 sections:




Susquehanna Flats, Upper  Eastern Shore, Upper Potomac River, Tangier Island




Complex, Lower Eastern Shore,  New Point Comfort Region, York River and Lower




Western Shore.  Decreases were measured in 1 3 of the 21 sections:  Upper




Western Shore, Chester River,  Central Western Shore, Eastern Bay, Choptank




River, Patuxent River, Middle  Western Shore, Lower Potomac River, Middle






                                  -74-

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Eastern Shore, Reedville,  Rappahannock  River Complex, Mobjack Bay Complex
and James River.
     In the Upper Bay zone,  although  there was an increase noted, all of
this occurred on the Susquehanna Flats  where 95$ of the area was classified
as very sparse «10/K coverage).   Independent aerial and ground surveys of
this area in 1982 and 1984,  respectively, indicate that there has been an
expansion of SAV  in this section since  1978 but that the vegetation is very
patchy and not readily apparent  on  higher altitude photography.  Most of the
SAV observed on the Susquehanna  Flats was Myriophyllum spicatum (milfoil)
with Vailisneria  americana (wild celery) occurring in lesser abundance.   A
total of only 2 species were noted  in the ground surveys in 1984, in
contrast to the 15 species found here in the late 1950's (Bayley, et al.,
1978; Orth and Moore, 1984).   Reductions of SAV were recorded in the Upper
Eastern Shore and Upper Western  Shore sections.  Although, there was some
loss of the aerial imagery from  these two sections, the Md.DNR ground survey
showed reductions of SAV in these areas.
     SAV in the Middle Bay zone  was reduced from 1978 to 1984:  4,446 to
984 hectares, respectively.   Seven  of the eight sections showed a decline of
SAV.  In one of these sections,  Lower Potomac River, aerial photography
obtained late in  the season may  have  resulted in an underestimation of SAV
abundance.   Ground surveys by USGS  and  NVCC personnel documented SAV
presence at a number of stations in areas that did not show SAV in the
aerial photography.   Given the survey information for 1984, and what was
observed for the  entire Potomac  River in 1984, the actual abundance of SAV
in the Lower Potomac River was at least equal to that recorded in 1978.   The
Upper Potomac River section was  the only area of the river to show a
significant increase.  No  aerial photography of the Upper Potomac was
                                  -75-

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obtained in 1970 and  ground surveys found no SAV through 1981.   From 1981  to
1984, 631  hectares of river bottom became vegetated with SAV.   This increase
includes not only many native species but also significant populations of
two species not recorded  in earlier surveys of the river:  Hydrilla
verticillata (Hydrilla) and Heteranthera dubia (water stargrass).  Since
Hydrilla has become a problem species in other areas of the U.S., there is
concern over its increase to nuisance levels in certain sections of the
Potomac.  The river should be carefully monitored in succeeding years to
follow the growth of  Hydrilla as well as other native species.
     The Lower Bay zone showed an increase of 1778 hectares since 1978 (19?)
with most of the increase (82%) occurring in the Tangier Island Complex.
Increases in SAV beds in  the York River have been observed to occur from
seed recruitment from nearby vegetated areas.  This increase was also noted
in 3 of the 6 historical  sites in this zone:  Jenkins Neck, East River and
Fleets Bay.  As in 1978,  no SAV was observed at two sites  (Mumfort Island
and Parrott Island).   The sixth site, Vaucluse Shores, has remained
relatively stable since 1978.
     In summary, although the total amount of SAV in the bay in  1984 is
somewhat less than that found in 1978, both increases and decreases have
been observed in particular sections.  Most of the decrease has  occurred in
the region from just  below the Susquehanna Flats to Smith Island.  This
decrease in vegetation during the last 6 years has also been noted by the
Md.DNR vegetation survey  (Table 8, Fig. 17).  The number of sampled stations
with SAV has continued to decrease from earlier years.  In 1984, only H.0%
of the stations were  vegetated compared to 9.5% in 1978.  Seventeen of 26
areas were without any SAV compared to 12 in 1978. However, certain
procedures used in the Maryland DNR survey, such as stations located in
                                  -76-

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Figure 17.   Trends in occurrence  of SAV  in  the Maryland portion of the
            Chesapeake Bay,  1971-1984.   Values represent the percentage of
            stations with vegetation  (N  = 644) and  the percentage of
            unvegetated areas  (N  = 26).
                                  -77-

-------
SV3HV JO !N30y3d
                                 (T
                                 <
                                 UJ
SNOI1V1S  dO lN30H3d

-------
waters too deep to support SAV  growth,  may  be resulting in a skewed or an




unrealistically low impression  of total SAV presence.




     Increases in SAV have been noted in  the Upper Potomac River,




Susquehanna Flats and at a number of  locations  in the Lower Bay zone.  The




increase of SAV in the upper Potomac  River  may  be related to nutrient




changes in this part of the river,  primarily from a reduction in phosphate




loading and suspended solids from the Blue  Plains sewage treatment plant and




the initiation of nitrification in  1983.  The causes for the increase in SAV




in several sections and decreases in  others is  not known, but annual




monitoring of SAV populations along with  the monitoring of nutrient and




light parameters at these areas is  essential for generating any significant




correlative data.  In addition, the success of  various transplant efforts by




both states should be examined  carefully  with regard to the nutrient and




light regimes found in those river  systems  where the transplanting is being




conducted.  These data will be  critical in  understanding the success at




these sites.
                                  -78-

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                                 SECTION  6




                              LITERATURE  CITED




Allaire, R. A., K. W. Potts,  T.  P.  Sheehan  and N.  R.  Sinclair.   1985.




     Shoreline survey of submersed aquatic  vegetation including  Hydrilla  in




     the transition zone of the  Potomac River  during  the summer  and fall  of




     1984.   Final Report.  U.S.  Army Corps  of  Engineers.  Contract No. DACW




     31-82-D-007.  40 pp.



Anderson, R.  R. and R.  T. Macomber.   1980.   Distribution of  submersed




     vascular plants Chesapeake  Bay, Maryland.   U.S.  EPA.  Final Report.




     Chesapeake Bay Program.   Grant  No. R805970.   126 pp.




Bayley, S., V. D. Stotts, P.  F.  Springer  and J.  Steenis.  1978.  Changes  in




     submerged aquatic macrophyte populations  at  the  head of  the Chesapeake




     Bay, 1958-1974.   Est.  1:171-182.




Carter, V., N. B. Rybicki,  R.  T.  Anderson,  T.  J,  Trombley and G. L. Zynjuk.




     1985a.  Data on the distribution  and abundance of submersed aquatic




     vegetation in the tidal  Potomac River  and transition zone of  the




     Potomac estuary, Maryland,  Virginia, and  the District  of Columbia,




     1983 and 1984.  U.S. Geological Survey Open-File Report  85~82.  65 pp.




Carter, V., J. E. Paschal,  Jr. and N.  Bartow.   1985b.  Distribution and




     abundance of submersed aquatic  vegetation in the tidal  Potomac River




     and estuary, Maryland and Virginia,  May 1978 to  November 1981.  U.S.




     Geological Survey Water-Supply  Paper 2234A.   54  pp.




Haramis, G. M. and V. Carter.   1983-  Distribution of submersed  aquatic




     macrophytes in the tidal Potomac River.   Aquat.  Bot. 15:65-79.




Kemp, W. M.,  W. R.  Boynton, R. R.  Twilley,  J.  C.  Stevenson and L.  G. Ward.




     1984.   Influences of submersed  vascular plants on ecological  processes







                                  -79-

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     in upper Chesapeake Bay.   pp.  367-394.   In:  V. S. Kennedy  (ed.).  The




     estuary as a filter.   Academic Press, Inc., New York.




Orth, R.  J.,  K. L.  Heck, Jr. and  J. van Montfrans.  1984.  Faunal




     communities in seagrass communities:  A  review of the influence of




     plant structure and prey  characteristics on predator-prey




     relationships.   Est.  7:339~350.




Orth, R.  J.  and K.  A. Moore.   1981.   Submerged aquatic vegetation in the




     Chesapeake Bay:   past, present and future.  P. 271-283.  In:  Proc.




     46th North American Wildlife and Natural Resources Conf. Wildlife




     Manage.  Inst.,  Wash.,  D.C.




Orth, R.  J.  and K.  A. Moore.   1982.   The  biology and propagation of Zost?ra




     marina,  eelgrass, in the  Chesapeake  Bay, Virginia.  U.S. EPA.  Final




     Report Chesapeake Bay Program.  Grant No. R805953.  187 pp.




Orth, R.  J.  and K.  A. Moore.   1983.   Chesapeake Bay:  an unprecedented




     decline in submerged aquatic vegetation.  Sci. 222:51-53.




Orth, R.  J.  and K.  A. Moore.   1984.   Distribution and abundance of submerged




     aquatic vegetation in Chesapeake Bay:   an historical perspective.  Est.




     7 :531~540.




Orth, R.  J.,  K. A.  Moore and H.  H.  Gordon.   1979.   Distribution  and




     abundance of submerged aquatic vegetation in the lower  Chesapeake Bay,




     Virginia.  U.S.  EPA.   Final  Report.  Chesapeake Bay Program.  EPA-




     600 78-79-029/SAV1 .




Orth, R.  J.,  K. A.  Moore and J.  van Montfrans.   1982.  Submerged aquatic




     vegetation:  Distribution and abundance in  the lower Chesapeake Bay  and




     the interactive effects  of light, epiphytes  and grazers.  U.S. EPA.




     Final Report.  Chesapeake Bay Program.   Grant  No. X003246.  236 pp.






                                  -80-

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Rybicki, N.  B.,  V.  Carter,  R.  T.  Anderson  and T. J. Trombley.  1985.




     Hydrilla vertlcillata  in the tidal Potomac River, Maryland, Virginia,




     and the District of Columbia,  1983 and  1984.  U.S. Geological Survey.




     Open File Report 85~77.   28  pp.




Stevenson, J. C. and N.  M.  Confer.   1978.  Summary of available information




     on Chesapeake  Bay submerged  vegetation.  U.S. Dept. of Interior, Fish




     and Wildlife Service.   FWS/OBS-78/66.   335 pp.




Thayer, G. W.,  D. A. Wolfe  and R.  B. Williams.  1975.  The impact of man on




     seagrass systems.  Am.  Sci.  63=288-296.




U.S.E.P.A. Chesapeake Bay Program  Technical Studies.  A Synthesis.  1982.




     Final Report.   Washington, D.C.   635  pp.




Ward,  L. G.,  W.  M.  Kemp and W.  R.  Boynton.   1984.  The influence of waves




     and seagrass communities on  suspended sediment dynamics in an estuarine




     embayment.   Mar. Geol.   59:85-103.
                                 -81-

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                                 APPENDIX A

1TECIES OF SUBMERGED AQUATIC PLANTS  FOUND IN THE  CHESAPEAKE  BAY  AND
TRIBUTARIES (MODIFIED FROM CARTER,  ET AL. ,  1985)
  Family
       Species
Common name
Characeae
(muskgrass)
Najadaceae
(pondweed)
Chara brauni i Cm.
Chara zeylanica Km. ex Wild
Nitella flexilis (L).  Ag.

Potamogeton perfoliatus L.
Potamogeton pectinatus L.
Potamogeton cri spus L
Potamogeton pusillus L.
Ruppi a mari tima L.
Zanni chellia palustri s L.
Najas quadalupensis (Spreng.
  Morong
NaJ as gracill ima Magnus
Naias minor All
Muskgrass
Redhead-grass
Sago pondweed
Curly pondweed
Slender pondweed
Widgeongrass
Horned pondweed
Southern naiad

Naiad
Hydrocharitaceae
(frogbit)
Ceratophyllaceae
(coontail

Haloragidaceae
(watermilfoil)

Pondedariceae
(pickerelweed)

Potamogetonaceae
Vailisneria americana Michx.
Elodea canadenis (Michx.)
  Planch.
Egeria densa Planch.
Hydrilla verticillata (L.f.)
  Caspary

Ceratophyllum demersum L.
Myriophyllum spicatum L.
Heteranthera dubia (Jacqin)
  MacM.

Zostera marina (L.)
Wildcelery
Common elodea

Water-weed
Hydrilla
Coontail
Eurasian
watermilfoil

Water-stargrass
eelgrass
                                   -82-

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                                 APPENDIX B
TOPOGRAPHIC QUADRANGLES SHOWING THE  DISTRIBUTION AND ABUNDANCE  OF SAV  (1
<10J; 2 = 10-40?; 3 = ^0-70$;  4 = 70-100$)
                                   -83-

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   UNTOD tTATO
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                 r
                                    -84-

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                                                               NORTH KA«T QUADKANOLK
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                                                             >2
                                     -85-

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     SUBMERGED AQUATIC VEGETATION 13*4
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                  SUBMERGED AORMTKWEGETATUIN 1984
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                                                   .-/•

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                                                                  PERRYMAN MAffYLAMO
                                  -87-

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                                       -93-

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                                                -128-

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       -133-

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                                              -134-

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                                      -139-

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