Oxygen and Carbon Isotopic Data from Wellington Creek, Lorain County, Ohio

To test whether these organisms secrete their shell in isotopic equilibrium, the delta 18O values of shell aragonite are compared to ambient water temperature and delta 18O values monitored for > 1 year. These bivalves were chosen for study because they are abundant in surface sediments and cores from Lake Erie where they represent a source of information on the environmental history of the lake.

The observed mean values are -5.54% for A. grandis and -6.16% for S. striatinum. The mean delta 18O value expected for bivalve aragonite if equilibrium precipitation is occurring during May-August in Wellington Creek is -5.69%. The similarity between measured and predicted isotopic values for both species suggests that they are useful sources of paleoenvironmental data.