Nonmarine ostracods as Quaternary palaeoenvironmental indicators

Abstract

Ostracods are small, bivalved crustaceans with calcitic shells that are often well preserved in Quaternary sediment sequences. Although ostracods are found in most types of water body, work on Quaternary faunas has focused on marine environments. This paper, however, reviews the significant contribution that ostracods have also made to the study of nonmarine environments, particularly lakes. Although much of the early work on ostracods was taxonomic, recent studies have dramatically improved our understanding of ostracod ecology. Aquatic chemistry, in particular, has been shown to be an important control on the occurrence of nonmarine species. However, data are still lacking from many parts of the world and for many species. A knowledge of such controls is vital if ostracods are to be used as palaeoenvironmental indicators. An exciting development over the past decade has been the use of ostracod shell chemistry as a palaeoenvironmental tool. The stable isotope composition of the shell has been used in a number of studies to provide important information on palaeohydrology and palaeoproductiv ity of lakes. Furthermore, the trace-element geochemistry of ostracod shells has been used most successfully as a palaeosalinity and palaeotemperature indicator. Although nonmarine ostracods have yet to be used routinely as Quaternary palaeoenvironmental indicators, it is clear that they will play an increasingly important role with the collection of more ecological data and the development of new techniques.