USING THECAMOEBIANS AS INDICATORS OF ENVIRONMENTAL CHANGE WITHIN TODDS LAKE, MURFREESBORO, TENNESSEE

The Stones River watershed is located in Rutherford County, Tennessee and is the source of the city of Murfreesboro’s drinking water. Rutherford County has grown 44% in the last decade with the population of Murfreesboro increasing by 40,000 in the same time period. This growth rate is considered to be one of the highest in the nation and the watershed is considered to be impacted due to urban growth. Black Fox Spring, which begins in a Tennessee Wildlife Resources Agency protected wetland, travels through several subdivisions and receives runoff from lawns and driveways. It ends at Todds Lake in Murfreesboro. This lake was originally a wetland and after two dams were built it is now an artificial lake and reservoir for Murfreesboro. Todds Lake is also located near a subdivision, a strip mall, and a gas station, and could possibly be receiving runoff from those areas. Thecamoebians, microscopic invertebrates, can be used to study the water quality of an area with little or no disturbance to the area. Thecamoebians are benthic, living at or near the bottom of a body of water. This allows them to give a good indication of the conditions at the bottom of a freshwater environment. Thecamoebians are also very sensitive to changes in the environment and they have been used as pollution indicators in studies in North America and Europe. The shells of these organisms preserve easily, and they can be used to study ecological changes in the fossil record going back decades to centuries. Sediment samples have been collected from Todds Lake and the assemblage of thecamoebians, including Centropyxis aculeata and Arcella vulgaris, present in the lake indicate that it is currently a stressed environment. A sediment core will be retrieved from the lake and the thecamoebian communities in the core will be analyzed to determine if there have been changes in the ecological condition of this wetland and lake over the last two centuries.