DIATOM COMMUNITIES NEAR ACID MINE DRAINAGE AT GREEN VALLEY LAKE, WEST TERRE HAUTE, INDIANA

Green Valley Lake is located in West Terre Haute, Indiana, near an abandoned coal mine. Acid mine drainage (AMD) leaching from the site of the abandoned mine has impacted this area for almost 55 years. Seasonally, the pH of effluent streams drops as low as 3 in some areas. Elevated levels of SO₄, Fe, Al, and heavy metals occur in streams (and groundwater) that may contaminate Green Valley Lake.

Diatoms are a golden-brown algae with a siliceous skeleton; they are an important primary producers that are abundant and typically well-preserved as fossils in most lake systems. To explore the environmental impact of AMD on this system, we sampled the lake plankton and sediments for fossil diatoms, which are known to be highly sensitive to acidity in lakes and streams. The purpose of this study is to analyze the spatial distribution of diatoms in the lake and sediments. Samples were collected from the plankton and sediment from 11 locations around the lake. Our hypothesis is that diatom diversity should increase away from areas of riverine discharge into the lake. Results from this study will help determine how AMD has influenced the structure of the diatom community in the lake and provide a baseline measurement for the modern lake system so that the long-term resilience of these communities can be analyzed in future studies.