RECORDS OF LAND-USE IMPACTS ON BASS LAKE, OHIO USING PALEOLIMNOLOGY AND REMOTE SENSING

A paleolimnological investigation of recent sediments was conducted on Bass Lake, Geauga County, Ohio to assess anthropogenic impacts since settlement and remote sensing of aerial images was used to quantify changes in surrounding land-use pressures since the 1950's. Bass Lake is a recent acquisition of the Geauga Park District. The Bass Lake Preserve is comprised of the 65 hectare lake and approximately 245 hectares of surrounding land. Approximately 90 percent of the current shoreline is reforested or has extensive marsh vegetation. A 152 cm sediment core was taken in September 2006 and sub-sectioned at 1 cm intervals. The upper 100 cm were sub-sampled and analyzed for Pb210. Loss-on-ignition (LOI) analysis was conducted on all samples to determine organic carbon content. Select intervals were analyzed for fossil diatom assemblages based on changes in carbon content. Correspondence analysis was conducted to determine major changes in diatom assemblages, and changes in diatom-inferred total phosphorous concentrations were calculated from existing nutrient-optima data sets. Written historical records were collected to determine potential human impacts and compared with LOI carbon, diatom assemblage data, and GIS analysis of 20th century land-use changes. Evidence of early damming and dredging with recent eutrophication from development is seen in the carbon and diatom record. An initial increase in dry density occurs around 1900 and sedimentation increases to > 0.3 g cm-2 yr-1 after 1920. Diatom data show an assemblage shift from low-pH, low-nutrient species to higher-pH, higher-nutrient species. GIS results show a transition from heavy agricultural use in the watershed during the 1950's. Reforestation occurs during the 1960's and existing vegetation buffers may remediate impact of increased development that has occurred over the past decade.