Distribution of Submerged Aquatic Vegetation in the Chesapeake Bay and Tributaries and Chincoteague Bay - 1991
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W&M ScholarWorks Reports 12-1992 Distribution of Submerged Aquatic Vegetation In The Chesapeake Bay and Tributaries and Chincoteague Bay - 1991 R J. Orth Judith F. Nowak Virginia Institute of Marine Science Gary Anderson Virginia Institute of Marine Science Kevin P. Kiley Virginia Institute of Marine Science Jennifer R. Whiting Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/reports Part of the Environmental Sciences Commons Recommended Citation Orth, R. J., Nowak, J. F., Anderson, G., Kiley, K. P., & Whiting, J. R. (1992) Distribution of Submerged Aquatic Vegetation In The Chesapeake Bay and Tributaries and Chincoteague Bay - 1991. Virginia Institute of Marine Science, College of William and Mary. http://dx.doi.org/doi:10.21220/m2-031r-g688 This Report is brought to you for free and open access by W&M ScholarWorks. It has been accepted for inclusion in Reports by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. 11° oo' 76° 00' 75°00' 39° oo' 38° oo' 37° 0 10 20 30 oo' NAUTICAL MILES 11° oo' 75° oo· \/\rfl:S ~~ JJ~.i OG+ \~q I C,.3 Distribution of Submerged Aquatic Vegetation in the Chesapeake Bay and Tributaries and Chincoteague Bay - 1991 by Robert J. Orth, Judith F. Nowak, Gary F. Anderson, Kevin P. Kiley, and Jennifer R. Whiting Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, VA 23062 Funded by: U.S. Environmental Protection Agency (Grant X00346503) National Oceanographic Atmospheric Administration (Grant No. NAl 70Z0359-0l) Virginia Institute of Marine Science/School of Marine Science Maryland Department of Natural Resources (C272-92-005) U.S. Fish and Wildlife Service (14-16-0005-91-9023) Allied-Signal Foundation Final Report Submitted to: U.S. Environmental Protection Agency Chesapeake Bay Program Offic:e Annapolis, MD 21403 December 1992 Cover Photograph: Hydrilla verticillata in the Potomac River. (Photograph by Nancy Rybicki, USGS.) Inside Cover: Map of Chesapeake Bay and Tributaries and Chincoteague Bay. CONTENTS Page TABLES . iv FIGURES V EXECUTIVE SUMMARY . viii ACKNOWLEDGEMENTS xiii SAV SPECIES . 1 METHODS ... 2 Introduction . 2 Aerial photography . 2 Mapping process . 5 SAV perimeter digitization and area calculation 9 Tests of precision and accuracy . 9 Standard operating procedures . 11 Choice of representative SAV bed . 11 Conversion of SAV perimeter points from X,Y centimeters to Universal Transverse Mercator (UTM) coordinates in ARC/INFO format . 12 Calculation of 1991 SAV areas . 12 Organizational procedures for analysis . 13 Ground truth and other data bases . 17 RESULTS ...... 20 Data presentation 20 1991 Summary . 20 Upper Bay Zone . 20 Middle Bay Zone . 37 Lower Bay Zone . 37 Chincoteague Bay 38 Discussion of sections arranged within zones . 38 Upper Bay Zone . 38 Susquehanna Flats (Section 1) . 38 Upper Eastern Shore (Section 2) . 38 Upper Western Shore (Section 3) . 41 Chester River (Section 4) 41 Middle Bay Zone . 41 ii CONTENTS (continued) Page RESULTS (continued) Central Western Shore (Section 5) 41 Eastern Bay (Section 6) . 45 Choptank River (Section 7) . 45 Patuxent River (Section 8) . • • 45 Middle Western Shore (Section 9) 45 Lower Potomac River (Section 10) 50 Upper Potomac River (Section 11) 50 Middle Eastern Shore (Section 12) 53 Mid-Bay Island Complex (Section 13) 53 Lower Bay Zone . 53 Lower Eastern Shore (Section 14) . 53 Reedville Region (Section 15) . 57 Rappahannock River Complex (Section 16) 57 New Point Comfort Region (Section 17) 60 Mobjack Bay Complex (Section 18) . 60 York River (Section 19) ...... 60 Lower Western Shore (Section 20) 60 James River (Section 21) 65 Chincoteague Bay 65 LITERATURE CITED 68 APPENDICES . 71 A Species of submerged aquatic plants found in the Chesapeake Bay and tributaries . 73 B. Latitude and longitude coordinate points defining the 21 Chesapeake Bay sections and Chincoteague Bay 85 C. Topographic quadrangles for the Chesapeake Bay and Chincoteague Bay showing distribution, abundance, and ground trothing of SAV in 1991 . 89 Map Legend ...................... 90 D. Number of square meters of SAV for individual beds and totals for density categories for each topographic quadrangle in 1991 . 205 E. 1991 SAV ground truth data listed by topographic quadrangle and by SAV bed, cross referenced with 1990 SAV beds . 233 iii TABLES Number Page 1 Guidelines for acquisition of aerial photographs . 4 2 List of USGS 7 .5 minute topographic quadrangles for the Chesapeake Bay and Chincoteague Bay SAV study areas and corresponding code numbers . 7 3 Area descriptions for each of the 21 sections in the Chesapeake Bay SAV study area . 15 4 Total area of SAVin hectares by USGS 7 .5 minute topographic quadrangle for 1990 and 1991 . 21 5 Number ofhectares ofSAVin 1990 and 1991 for the 21 sections and three zones of the Chesapeake Bay, and for Chincoteague Bay . 26 6 Number of square meters of SAV in 1991 for each quadrangle of the 21 sections in the Chesapeake Bay and of Chincoteague Bay 27 iv FIGURES Number Page 1 Map of Chesapeake Bay and tributaries with Upper, Middle, and Lower zones, and Chincoteague Bay, with locations of all SAV beds in 1991 ix 2 Total hectares SAV for the Upper, Middle, and Lower zones of the Chesapeake Bay in 1991 . • . x 3 Total hectares SAV in 1991 by section of the Chesapeake Bay . xi 4 Map of Chesapeake Bay, its tributaries, and Chincoteague Bay with approximate locations of flight lines for 1991 SAV photo- graphy.............................. 3 5 Location ofUSGS 7.5 minute topographic quadrangles in the Chesapeake Bay, its tributaries, and Chincoteague Bay with corresponding code numbers . 6 6 Crown density scale used for determining density of SAV beds: (1) very sparse, 0-10%; (2) sparse, 10-40%; (3) moderate, 40-70%; (4) dense, 70-100% ................... 10 7 Location of Chincoteague Bay and Chesapeake Bay with Upper, Middle, and Lower zones and 21 sections used for delineation of SAV distribution patterns . , . 14 8 Distribution of SAV in the Susquehanna Flats (Section 1) 39 9 Distribution of SAV in the Upper Eastern Shore (Section 2) 40 10 Distribution of SAVin the Upper Western Shore (Section 3) 42 11 Distribution of SAV in the Chester River (Section 4) . 43 12 Distribution of SAV in the Central Western Shore (Section 5) . 44 13 Distribution of SAV in the Eastern Bay (Section 6) . 46 14 Distribution of SAV in the Choptank River (Section7) . 47 15 Distribution of SAV in the Patuxent River (Section 8) . 48 V FIGURES (continued) Number Page 16 Distribution of SAVin the Middle Western Shore (Section 9) . 49 17 Distribution of SAVin the Lower Potomac River (Section 10) 51 18 Distribution of SAVin the Upper Potomac River (Section 11) 52 19 Distribution of SAV in the Middle Eastern Shore (Section 12) 54 20 Distribution of SAVin the Mid-Bay Island Complex (Section 13) . 55 21 Distribution of SAV in the Lower Eastern Shore (Section 14) . 56 22 Distribution of SAV in the Reedville Region (Section 15) . 58 23 Distribution of SAV in the Rappahannock River Complex (Section 16) . 59 24 Distribution of SAV in the New Point Comfort Region (Section 17) 61 25 Distribution of SAV in the Mobjack Bay Complex (Section 18) 62 26 Distribution of SAV in the York River (Section 19) . 63 27 Distribution of SAV in the Lower Western Shore (Section 20) 64 28 Distribution ofSAVin the James River (Section 21) . 66 29 Distribution of SAV in the Chincoteague Bay . 67 30 Illustration of Chara spp. (Muskgrass) . 74 31 Illustration of Nitella spp. (Stonewort) . 75 32 Illustration of Najas guadalupensis (Southern naiad) . 76 33 Illustration of Vallisneria americana (Tapegrass) . 77 34 Illustration of Egeria spp. (Water-weed) . 78 35 Illustration of Hydrilla verticillata (Hydrilla) . 79 vi FIGURES (continued) Number Page 36 A comparison: illustrations of Hydrilla verticillata, Elodea canadensis, and Egeria spp. 80 37 A comparison: illustrations of Hydrilla verticillata, Elodea canadensis, and Egeria spp. 81 38 Illustration of Ceratophyllum demersum (Coontail) 82 39 Illustration of Trapa natans (Water chestnut) . 83 40 Illustration of Myriophyllum spicatum (Eurasian watermilfoil) 84 vii EXECUTIVE SUMMARY The distribution of submerged aquatic vegetation, principally rooted vascular macrophytes, in the Chesapeake Bay, its tributaries, and Chincoteague Bay was mapped during May to October 1991 at a scale of 1:24,000 using black and white aerial photography. SAV bed perimeter information was digitized and stored in a computerized data base. Ground truth information was obtained from the U. S. Fish and Wildlife Service, the University of Maryland Horn Point Environmental Laboratories, the Metropolitan Washington Council of Governments, the Maryland Department of Natural Resources, Harford Community College, Essex Community College SAV Research Group of Baltimore County, National Park Service, Assateague Island, and the College of William and MaryNirginia Institute of Marine Science/School of Marine Science. Citizen support via the U. S. Fish and Wildlife Service and Chesapeake Bay Foundation provided additional ground truth information. In 1991, the Chesapeake Bay had 25,623 hectares of SAV, compared to 24,296 hectares in 1990, with 2,158 hectares (8.4%), 11,664 hectares (45.5%), and 11,802 hectares (46.1%) occurring in the Upper, Middle, and Lower Bay zones, respectively (Figs. 1, 2, and 3). In 1991 seventy-eight percent (1,684 hectares) of the SAV within the Upper Bay zone was located in the Susquehanna Flats (Section 1). Eight species of SAV were documented by ground truth surveys in this section, with Myriophyllum spicatum being dominant. A recently introduced exotic species, Hydrilla verticillata, was found in the Flats but occurred in small isolated beds. Overall abundance of SAV declined from the 1990 (1,773 hectares) level, but the density of beds increased slightly from 1990. Eighty-nine percent of all SAV beds in the Flats were classified as very sparse (0-10% coverage), and 7% of beds were classified as dense (70-100% coverage).