STABLE CARBON ISOTOPE COMPOSITION OF MOLLUSCTISSUES: EVIDENCE OF FOOD SOURCES

Carbon isotope composition of the tissue of several mollusc species gathered from the Huaxi river, in China, a typical karst river, was analysed to determine their potential food sources. The results showed that delta C-13(tissues) values of gastropod species Cipangopaludina chinensis are about 3 parts per thousand heavier than the values of bivalve species Corbicula fluminea and Anodonta woodiana, which indicates the different food and nutrition sources between species. According to the delta C-13 values of mollusc's tissues and the potential food, bivalve species C. fluminea and A. woodiana mainly assimilate phytoplankton and terrestrial plant detritus as food, while gastropod species C. chinensis also utilize sediment organic matter as a food source excluding the phytoplankton and terrestrial plant detritus. Moreover, the preferential food selection behavior and varied metabolic intensity between different ages and individuals may lead to some variation of delta C-13(tissues) values of C. fluminea. This study will be helpful in defining the role of molluscs in the energy flow of the karst river ecosystem, and to protect and manage those molluscs' resources.