Spatial variation of cadmium concentration in the bivalve Beguina semiorbiculata (Linnaeus, 1758) from coastal coral reefs of Vietnam.

The spatial distribution of trace metals (Fe, Zn, Cu, Cd, Mn, Pb and Ni) in the soft tissues of Beguina semiorbiculata from coastal reefs of Vietnam was studied. Bivalves were collected in May 2013 from 22 sites along the south-eastern coast from Gulf of Thailand to Ha Long Bay. The most increased concentrations of studied metals (excluding Cd) were shown in the B. semiorbiculata living in Ha Long Bay characterized by terrestrial runoff and anthropogenic effects. In contrast, the maximal Cd concentrations were found in the bivalves from coastal reefs of central Vietnam and Gulf of Thailand. Apparently, Cd concentration depends on seasonal upwellings (central part of Vietnam coast) and composition of suspended matter (Gulf of Thailand). Consequently, Cd distribution in the coastal waters of Vietnam should be strongly controlled in relation with predicted risk of climate change that may further significantly increased Cd bioavailability for habitants of coral reefs.