TRACKING EUTROPHICATION THROUGH A CHAIN OF LAKES IN AGRICULTURAL INDIANA

Chain O’ Lakes State Park, located in northern Indiana, consists of nine interconnected lakes and four satellite lakes, with depths that range from 1 to 20 m. Park managers have reported increasing cyanobacteria blooms throughout last decade, which has resulted in periodic closure of on-site recreational facilities. Park managers are concerned about the impact on the lake ecosystems and tourism to the park.

Chain O’ Lakes State Park is bordered by farmland in the extreme northeast and southwest corners of the park, and has a correctional facility in the eastern-most section of the park. Some additional nutrient loading may be coming from leaks in the on-site sewage treatment plant associated with the corrections facility.

In the spring of 2013, we collected plankton from most of the lake systems, along with sediment cores from two lakes for diatom analysis. We found that most of the flora were dominated by species indicating elevated nutrient levels, however there were some trends between lakes. Diatom species indicative of higher phosphorus levels tended to be greatest in the eastern lakes, generally decreasing through the chain westward, but peaks again in the westernmost lakes, possibly as a result of agricultural runoff.

Our project is designed to explore the impact of eutrophication through a chain of interconnected lakes, and the impacts of human development and agriculture on the system of lakes over the last two centuries. We will be analyzing a series diatom assemblages from short cores taken from each lake in the system. One long core will be taken from Long Lake in order to establish a baseline nutrient level for the lake systems. Charcoal will be analyzed to establish when Native Americans first colonized the area. We ultimately intend to compare the timing of eutrophication within individual systems as a means of exploring the influence of lake hierarchy on nutrient cycling in a flow-through system.