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PROPOSED USE OF LENGTH ALONG SHORELINE OF EELGRASS BEDS AS A MEASURE OF SUBMERGED AQUATIC VEGETATION (SAV) IN EMBAYMENTS
Citation:
Pesch, C, D McGovern, G Cicchetti, AND J S. Latimer. PROPOSED USE OF LENGTH ALONG SHORELINE OF EELGRASS BEDS AS A MEASURE OF SUBMERGED AQUATIC VEGETATION (SAV) IN EMBAYMENTS. Presented at New England Estuarine Research Society Annual Meeting, Block Island, RI, October 6-9, 2004.
Description:
The U.S. EPA's Atlantic Ecology Division (AED) has a multi-year research program to develop empirical nitrogen load-response models for embayments in southern New England. This research program is part of EPA's Aquatic Stressors Program, which is designed to provide managers with tools to manage aquatic environments. As part of this program, AED is developing a nitrogen load-response model with submerged aquatic vegetation (SAV) as one endpoint, using SAV measurements from aerial images of 44 embayments along the Connecticut, Rhode Island, and southern Massachusetts shores. Because of the large number of study systems and the need to develop a rapid, inexpensive method of measuring SAV, a linear measurement of eelgrass beds rather than the traditional area measurement was proposed. In order to test this proposed method, an existing map of eelgrass beds in Massachusetts (1999, MassGIS) was used to examine the relationship of the linear measurement (length of eelgrass bed along the shoreline) to area. When the length along the shoreline of eelgrass beds (summed by embayment) was plotted against area (summed by embayment) for 23 Massachusetts embayments there was a strong curvilinear relationship. When length along shoreline of individual beds in the 23 Massachusetts embayments was plotted against area of individual beds, the relationship was not as good. When the total area of eelgrass beds per embayment is large (> 1,000,000 sq m) and the embayment has a complex shoreline with islands there is more variability. However, for embayments of moderate size and complexity, and eelgrass bed area < 1,000,000 sq m, length along the shoreline seems to provide a good approximation of SAV.