Paper No. 2
Presentation Time: 9:00 AM-6:00 PM


DAVIDSON, Max I., Union College Geology Department, 807 Union St, Schenectady, NY 12308, GILLIKIN, David P., Department of Geology, Union College, 807 Union St, Schenectady, NY 12308, GOODWIN, David H., Department of Geosciences, Denison University, 100 Sunset Hill Drive, Granville, OH 43023 and WATTERS, G. Thomas, Department of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43212,

Freshwater bivalve shells record geochemical information at the time of precipitation. Most of the C that forms the shell is precipitated from dissolved inorganic carbon (DIC). Therefore shells may record d13CDIC and provide an archive of biogeochemical cycles. However, metabolic C (Cm) that is incorporated into bivalve shells can reduce the precision of the d13CDIC archive. To constrain the fidelity of freshwater shells as d13CDIC recorders, we monitored a plethora of water parameters including d13CDIC and d13CPOC every week for one year at the Columbus Zoo and Aquarium Freshwater Mussel Conservation and Research Center and adjacent O’Shaughnessy Reservoir in Ohio. Lampsilis cardium that grew in this water were collected and shells and tissues were analyzed for C isotopes. Based on samples collected from the commissure of the shell, percent Cm on two collection dates was 17.0% and 15.3% in September and December, respectively. We plan to investigate high resolution variations in Cm over the year in several shells. Shells are currently being serial sampled to allow calculation of Cm over the full year with a resolution of ~1 week. Moreover, we conducted an experiment to determine the d13C value of respired carbon in this species to assess if the error associated with using soft tissue d13C as a proxy of respired carbon d13C. These results will allow the use of the d13Cshell proxy to be used with more confidence in L. cardium.