Interpreting the paleoenvironmental, paleoclimatic and life history records in mollusc shells

The shells of fossil bivalve molluscs contain a wealth of paleoenvironmental, paleoclimatic, and life history information, preserved as physical and chemical variations within the shell. To interpret the shell records, stable oxygen and carbon isotopic profiles were studied across annual shell increments, in modern species and compared with measured oceanographic parameters. Isotopic profiles were found to track the annual temperature and salinity cycles, reflect thermocline developmentrecord productivity patterns on the continental, shelf, and provide information on age and season of death. Pleistocene shells from the U.S. Atlantic Coastal Plain reveal paleoseasonality and life history data similar to today, except that isotopic profiles may be offset by amounts which reflect the effect of global climatic changes upon the isotopic composition of sea-water.