USING THECAMOEBIANS AS INDICATORS OF ENVIRONMENTAL IMPACTS IN THE CLINCH AND POWELL RIVER WATERSHED, VIRGINIA

The Clinch and Powell River watershed in southwest Virginia is one of the most biodiverse river systems in North America. The watershed supports a diverse aquatic ecosystem with over 40 species of native freshwater mussels and over 120 species of native fish. Declines have been observed in the distribution of the mussel fauna over the past century. These declines are likely due to sedimentation and habitat degradation from urban, industrial, commercial and residential development; agricultural land use; contaminant spills and coal mining. Thecamoebians, testate amoebae, have been used increasingly in ecological research where they have proven to be valuable tools for examining the spatial variability of anthropogenic impacts. Rarely have they been used in examining the ecology of rivers. Thecamoebian assemblages were analyzed from sediment samples collected throughout the Clinch and Powell River watershed. These assemblages can be used to differentiate between favorable environments in lakes at high elevations which are remote from urban areas and unfavorable environments in tributaries that continue to be subjected to acid mine drainage. Small-diameter short cores were also collected from the watershed as the preservation potential of the shells of thecamoebians allows the collection of quantitative historical data. Comparisons will be made between thecamoebian assemblages in core samples and known land use changes such as that seen in Wetlands Estonoa. In the early 1900s the wetland began as a wet cornfield. It then became a town swimming hole, followed by an illegal trash dump and is now a reclaimed wetland being preserved by high school students. The comparison of recent historical thecamoebian assemblages with present day assemblages should help develop methods for using thecamoebians to evaluate the environmental impacts in this watershed and provide a tool for aiding in mitigation and restoration efforts in this area.