Trace metals in the American oyster, Crassostrea virginica, and sediments from the coastal lagoons Mecoacan, Carmen and Machona, Tabasco, Mexico

The concentrations of trace metals (Pb, Cd, Zn, Cu, Fe, and Cr), from three coastal lagoons (Mecoacan, Carmen and Machona) in the southern Gulf of Mexico, were measured in oysters and recent sediments. The mean values in oysters were lower than those found in the northern Gulf of Mexico, with the exception of copper in Mecoacan and chromium in the three lagoons. The mean values in sediments were much lower than those in the northern Gulf, with the exception of cadmium, that presented similar values in both places. Significant correlations were found between the condition index and salinity (r=0.645) and the concentration of copper (r=−0.652). It is concluded that the diminishing yields of oysters in these lagoons is due to a complex interaction of coastal zone and fisheries mismanagement, the presence of parasites and pollution.