EFFECTS OF COAL MINING ON SURVIVORSHIP AND TAPHONOMY OF THE ASIAN CLAM

We propose that mining activity occurring in the New River Basin (NRB) of Tennessee is greatly enhancing dissolution rates of freshwater mussel shells, increasing mortality and thus negatively impacting aquatic ecosystems and our ability to access their record. Our study, in mining impacted waters of the NRB, involves measuring the mortality rates of live Corbicula fluminea assemblages and the shell dissolution rates of their death assemblages to gather information supporting this hypothesis. The freshwater molluscan record provides information on paleoecology and paleoclimates. The freshwater record also helps us understand species composition changes on part of anthropogenic activities (Cummins 1994). Surface coal mining activity is capable of erasing this record. The taphonomic effects of changing water chemistry can have an important impact on paleontological analysis including live/dead fidelity, size frequency distributions, numerical abundance, and biomass estimates (Cummins 1994). A long history of such surface coal mining exists in the NRB of Tennessee and in recent years these mining practices have escalated (Bullock 2007). To measure the effects of mining on living mussels, silos containing live Corbicula fluminea were placed in several localities in creeks of the NRB that receive mining drainage. To measure the effects of mining on shell dissolution rates, mesh bags containing shells of Corbicula fluminea were also placed in several localities in creeks of the NRB that receive mining drainage. The weight of these shells were periodically measured, over the course of many weeks, to determine the rate of dissolution. To assess the factors affecting mortality rates and dissolution rates of shells, we measured water velocity as well as several chemical parameters: calcium, pH, sulfate, and conductivity. Our preliminary findings indicate that survivorship is influenced by most of these variables. We find that dissolution rates of the dead shells are also influenced by these factors and that the rates are relatively high, on the order of 5-10% per year, indicating that all fossil evidence of the dead will be gone in a time frame of less than a few decades.