MOLLUSKS AS LAKE-LEVEL INDICATORS IN CRYSTAL LAKE, OHIO

Crystal Lake is a kettle lake located in Medway, Ohio, formed by retreating glaciers at the end of the Pleistocene. It is located in a private community of approximately 500 residences whose owners have a vested interest in the lake as it is the focal point of their community. In 2007, T. Lowell and colleagues extracted a sediment core for scientific study. The core is believed to contain a nearly complete geologic record spanning approximately 15,000 years. This study will attempt to reconstruct lake levels during this period from the end of the Pleistocene until today.

If lake levels have remained stable, then that should be reflected in the mollusk communities preserved within the core, as each species of mollusk lives at a characteristic depth range. Samples taken from the core are sieved, all mollusk fossils removed for identification, and terrestrial organic matter preserved for future carbon dating. The study is currently ongoing. Five samples have been analyzed. Data supports a depth of 3 meters in at least one portion of the lake as indicated by the presence of V. sincera in all samples analyzed which preserved mollusk remains.

Future research is needed before any assessments can be made to determine past climate and biotic assemblages of Crystal Lake. Ongoing research will continue through the spring of next year, working from Pleistocene to Holocene sediments. Radiocarbon dating of one sample is currently underway at an independent lab, and results from that test are expected soon. In the spring, the live fauna of Crystal Lake will be sampled and compared to fossil assemblages from the core. Other areas of future research include using existing sediment-composition data from LOI to explore how it relates to mollusk-fossil density.