ANTHROPOGENIC INFLUENCES ON NUTRIENT FLUXES IN MODERN RECREATIONAL LAKE SYSTEMS: EXAMPLE FROM CHAIN O’ LAKES STATE PARK, INDIANA

Chain O’Lakes State Park (COLSP) is located in northern Indiana and is a popular destination for recreation in the area. COLSP is a 2,718 acre park with 9 interconnected kettle lakes and 4 satellite lakes. Over the last decade some of the lakes have experienced cyanobacteria blooms likely due to increased nutrient fluxes into the lakes from agricultural runoff and a nearby leaking septic system. The increasingly eutrophic conditions have compromised water quality and reduced recreational opportunities at COLSP. Management at COLSP would like to reduce nutrient fluxes and return the lakes to a more pristine state. In an effort to identify the pre-anthropogenic conditions of the lakes, sediment cores were collected to evaluate temporal and spatial variability in fossil diatom assemblages and sediment geochemistry. In the fall of 2013, short (<1m) sediment cores were collected from the 9 interconnected lakes at COLSP, and in spring 2014 a longer core (1.5 m) was collected from Long Lake. Detailed phosphorus (P) geochemistry is being used to better understand the history of nutrient burial in COLSP resulting from land use change (pre-settlement to modern) and cultural eutrophication. Preliminary results from Long Lake suggests that total P concentrations have been relatively constant throughout the core, except for two maxima in P concentrations at 20 cm and 10 cm. Ongoing work includes detailed P geochemistry for the short cores and the determination of metal concentrations. Once dates have been obtained for the cores, an assessment of nutrient and metal loading over time will be possible. Geochemical and biologic records from these cores will help us determine the paleo-pristine conditions for this region, and it will help us better understand human impacts on this lake system.