DATING LACUSTRINE MOLLUSCAN SUBFOSSIL ASSEMBLAGES USING AAR TECHNIQUES TO ASSIST IN RECONSTRUCTING THE PALEOCOMMUNITIES OF TEMPERATE WISCONSIN LAKES

The majority of environmental conservation studies and efforts focus on recent conditions, overlooking past ecosystem states. However, the emerging field of conservation paleobiology changes this approach by using the geologic record to establish environmental and biological baselines from which to analyze deviation. Paleoecological and historical reconstructions of lacustrine ecosystems have proven particularly informative for assessing changes in environmental quality. Here, we present data from surface and core-collected molluscan subfossil assemblages from Shadow Lake, a remediated lake in Wisconsin. In order to estimate the degree of time-averaging in the core’s assemblages, we selected gastropods from the upper, middle, and lower sections of the core for amino acid racemization (AAR) dating with radiocarbon calibration. Understanding the degree of time-averaging allows us to more accurately interpret data on paleocommunities as part of a larger environmental investigation. We can determine the effectiveness of current lake remediation practices in regards to recovering molluscan communities by comparing the time-averaged, historical species compositions to Recent assemblages. If lacustrine remediation efforts have been effective in reducing and eliminating anthropogenic pressures, we expect to find a return of the molluscan communities to a state similar to that of the baseline (pre-impact) community. This reconstruction of the biological community can then be correlated with other proxy records to inform and improve future conservation efforts.