USING MICROSCOPIC INVERTEBRATES TO ASSESS WATER QUALITY IN URBAN AND NON-URBAN LAKES IN TENNESSEE AND VIRGINIA

The states of Tennessee and Virginia have few natural lakes, with most lakes in these states created by the impoundment of streams to create swimming holes, ponds for watering cattle or horses, drinking water reservoirs, or for flood control. These lakes face a variety of pollution sources such as agricultural and urban run-off and acid mine drainage. Thecamoebians (testate amoebae) are microscopic, single-celled organisms that build a mineralized shell which is preserved in the fossil record. They are found in all freshwater environments, including those with sufficient moisture such as tree bark, wet moss, wet soil, and peatlands. In the last 35 years they have been used increasingly in paleoenvironmental studies to detect eutrophication, deforestation and land clearance, pH and salinity changes, and heavy metal and organic pollution. These studies have been mostly limited to Canada and Europe. We have sampled lakes in Tennessee and Virginia to determine the utility of thecamoebians as a cost-effective tool to assess water quality change in the southeast. The fossilization potential of these organisms gives them an advantage over other micro- and macroinvertebrates. Sediment samples from the lakes have been collected to determine the current faunal distribution in the region. Sediment cores have been collected to analyze changes in thecamoebian populations in the decades since impoundment to determine if recent changes in land-use or pollution of the lakes can be distinguished in the fossil record. Lakes assessed include Todds Lake in Tennessee and Wetlands Estonoa, Lake Keokee, and Lake Witten in Virginia. The thecamoebian communities from the urban lakes, Todds Lake and Wetlands Estonoa, will be compared with the communities from Lake Keokee and Lake Witten, which are both remote from urban areas and possibly more environmentally pristine. Case studies at the urban lakes have been completed by undergraduate students at Middle Tennessee State University.