USING TESTATE AMOEBAE TO ANALYZE WATER QUALITY AND ENVIRONMENTAL CHANGES IN THE CLINCH AND POWELL RIVER WATERSHED, VIRGINIA OVER THE LAST 100 YEARS (Invited Presentation)

Testate amoebae (also known as thecamoebians or arcellaceans) have been used in paleoenvironmental studies around the world to detect environmental changes such as eutrophication, pollution, deforestation and land use changes. They are microscopic, unicellular organisms found in all freshwater environments including rivers, lakes and peatlands. They build a mineralized shell or test that is either secreted by the organism or built using agglutinated (xenosomic) particles and this test can be preserved in the fossil record. While studies focusing on these organisms have become increasingly common they are still an underutilized group and few of the studies focusing on testate amoebae have been conducted in the southeastern United States.

The Clinch and Powell River watershed in southwest Virginia is one of the most biodiverse river systems in North America. Declines have been observed in the distribution of the mussel and fish fauna recently, likely due to sedimentation and habitat degradation from development, agricultural land use, contaminant spills and coal mining. Work on testate amoebae assemblages in this watershed has allowed me to distinguish between populations found in two distinct environments. Samples from unfavorable environments, such as those potentially affected by acid mine drainage or soil erosion from coal mining, are defined by low numbers of testate amoebae and dominant species of Centropyxis and Arcella. Populations found in samples from healthy environments, such as remote lakes at high elevations, are defined by high numbers of testate amoebae and diverse assemblages of Difflugia species.

The current study focuses on sediment cores collected from streams and lakes within this watershed. Virginia has very few natural lakes, with most being created by the impoundment of streams within the last 100 years. The main aim of this study is to determine if changes in recent land use can be detected in the fossil records of testate amoebae from these locations. An additional objective is to look at xenosomic particle selection of testate amoebae from the different locations to determine if test construction has been affected by environmental changes like land use changes.