Cadmium and silver in Mytilus californianus transplanted to an anthropogenic influenced and coastal upwelling areas in the Mexican Northeastern Pacific

Mussels Mytilus californianus were transplanted to coastal waters off Baja California, Mexico, to examine the spatial and temporal variations in cadmium and silver levels. One site was Islas Coronado, and the second was Punta Banda. The mussels were sampled during the upwelling period of April September 1989 and during the non-upwelling period of January March 1990. Cadmium and Ag concentrations were normalized relative to the condition index of the mussels. Throughout the study, Cd concentrations were higher in mussels at Punta Bunda than at Islas Coronado, and highest values were recorded between April and July. Silver concentrations were higher in mussels at Islas Coronado than at Punta Banda. At Punta Banda, Ag concentrations were high in the intermediate months of the study, while at Islas Coronado, concentrations were high at the end of the study period. Cadmium appeared to be associated with upwelling at both locations, but Ag at Islas Coronado appeared to be anthropogenic, as indicated by the negative correlation between Ag and the condition index.