Status of Some Heavy Metals in Tissues of Wedge Clam, Donax Scortum (Bivalvia: Donacidae) Collected from Padukere Beach, Karnataka

The wedge-clam, Donax scortum is a filter-feeding bivalve and is one of the few clams collected for food by the coastal population, especially the fishermen community, around Padukere (Karnataka) on the south-west coast of India. The samples of D. scortum were collected from Padukere beach from February 2009 to January 2010 at monthly intervals. The concentrations of five heavy metals (Cu, Pb, Fe, Cr and Ni) were detected in tissues of wedge clam, D. scortum. The concentrations of heavy metals were determined by Atomic Absorption Spectrophotometer (AAS, GBC 932 plus). The concentrations of those metals were in the order of Fe>Cu>Ni>Pb>Cr in the study area. The mean concentrations of the heavy metals, viz., Cu (19.38 μg/g dry weight), Pb (7.56 μg/g dry weight) and Cr (5.38 μg/g dry weight) in the wedge clam were below the permissible limits except for Ni (14.26 μg/g dry weight). Results indicated that higher concentrations of Cu, Pb and Ni were found in larger D. scortum. The present study showed seasonal variations of accumulation of metals in the donacids. The hierarchical cluster analysis using complete linkage showed two major groups of seasonal variation of heavy metals in wedge clams.