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Distribution and abundance of submerged aquatic vegetation in the lower Chesapeake Bay, Virginia
| Content Provider | Semantic Scholar |
|---|---|
| Author | Orth, Robert J. Moore, Kenneth A. Gordon, Hayden H. |
| Copyright Year | 1979 |
| Abstract | The distribution and abundance of submerged aquatic vegetation (SAV) in the lower Chesapeake Bay and its tributaries were delineated with color aerial photography and surface information. Over 8500 hectares of SAV were identified on 31 topographic quadrangles. To enable computer retrieval of the aerial resource information, all information from the 1978 mapping effort was entered into a data base based on the Universal Transverse Mercator coordinate system. The greatest concentrations of SAV were found at the mouths of the largest tidal rivers and creeks along the Chesapeake Bay shoreline, and to the east of Tangier and Great Fox Islands. Freshwater and low salinity portions of Virginia's tidal rivers were generally found lacking in large areas of SAV, although numerous small fringing beds and pocket areas associated with adjacent tidal marshes were identified. Based on the co-occurrence of the 20 species found at 93 locations throughout Virginia's tidal waters three species associations of SAV were identified. Zostera marina and Ruppia maritima dominated the higher salinity regions, Zannichellia palustris and others the lower salinities regions and Ceratophyllum demersum and others in the freshwater regions. Of the total of 20 species of SAV that were identified, 18 of the species occur primarily within the tidal rivers. Species richness was inversely related to salinity with the low salinity areas having the greatest number of species. Seventeen transects conducted across large SAV beds in six areas around the Chesapeake Bay shoreline revealed Ruppia to be dominating the shallow, more protected areas (+1 to -4 dm) with Zostera and Ruppia co-occurring at intermediate depths (-4 to -8 dm) and Zostera predomi.nating at deeper depths (-8 to -12 dm). Bottom types varied from silts to coarse sands with variations in sediment not directly related to speciation of these two species. Analysis of the historical distribution of SAV throughout the lower Bay was accomplished by use of aerial photography for six selected areas. Low levels of SAV in 1937 increased significantly until approximately 1971 when a precipitous decline in coverage occurred during the period of 19731974. This decline continued until 1978 when the lowest levels in SAV over the last 40 years were recorded. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=3019&context=reports |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
