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GIS Map Gallery: August 2003


Spatial Analysis of Freshwater Mussel Sampling

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Spatial Analysis of Freshwater Mussel Sampling

Freshwater mussels are some of the most imperiled wildlife within Virginia. As part of Virginia Department of Game and Inland Fisheries' freshwater mussel conservation effort, biologists are intensively surveying river segments in Southwest Virginia. Data from these surveys will provide baseline information for monitoring recovery efforts. The images above display results of one survey area. The map in the upper left corner displays the 875 sample points overlaid on an aerial photograph. Bottom depth, total number of mussels (abundance), total number of mussel species (richness), and presence of threatened or endangered species (T&E species) were recorded at each site. These variables can then be extrapolated over the entire study site. The primary map shows an extrapolation of predicted mussel abundance, with low abundance shown in blue and high abundance in red. Green circles represent T&E species observations. Depth contours or 3-dimensional profiles can also be created. Depth is displayed in the lower left-hand corner. Future mussel surveys can be compared to these spatial data to determine trends in populations. By recording and analyzing habitat information (e.g., depth, flow, substrate), it is also possible to model where species may occur in other areas of the river or the watershed.

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