Bioaccumulation of heavy metals in oyster (Saccostrea cucullata) from Chabahar bay coast in Oman Sea: Regional, seasonal and size-dependent variations

The concentration of heavy metals was determined in tissues of oyster, Saccostrea cuccullata, phytoplanktons and water samples from intertidal regions of the Chabahar bay, Oman sea. Oysters were collected from 5 stations and during spring, summer and autumn seasons. The heavy metals content in oysters, planktons and water samples showed variations depending on season, sampling station and size of the oysters. The heavy metals in water, plankton and tissue of oyster were higher in summer and the lowest metal contents were observed in autumn. The oyster tissue samples of size-class had lowest concentrations of Co, Pb, Ar and Cu. The maximum tissue levels of Ar, Cu, Ni and Zn were observed in oysters of size-class II while the values of Cd, Co and Pb had maximum levels in those of size-class III. The minimum levels of Cd and also Ni and Zn were found respectively in tissue of the oysters of size-class II and size-class III. There were significant differences in heavy metal content of oyster tissue, planktons and water samples between sampling stations. In all sampling stations and during all sampling seasons, the concentrations of heavy metals (except Cu) were almost higher in soft tissues than in hard tissues of oysters especially in oysters of size-class II and III. Seasonal analysis of tissue heavy metal content of oysters showed no significant differences between sampling stations.