Accumulation of silver from the diet in two marine benthic predators: The snow crab (Chionoecetes opilio) and American plaice (Hippoglossoides platessoides)

The kinetics and fine-scale tissue distribution of a single dose of Ag-110m ingested with food were determined in snow crab and American plaice throug h the techniques of in vivo gamma counting and whole-body autoradiography. Metal that was retained after the first 3 d was distributed in all the soft tissues of snow crab, whereas it concentrated in gut, liver, and gallbladd er of the American plaice. In snow crab, the biological half-life of retain ed Ag,which represented 67-100% of the ingested dose, was greater than 1000 d. In contrast, in American plaice the retained fraction represented only 4-16% of the ingested dose and the biological half-life ranged from 13 to 1 02 d. Modeling the trophic accumulation of Ag for snow crab and American pl aice living in the St. Lawrence Estuary, assuming realistic values for food ingestion rates and Ag concentration in benthic organisms of lower trophic levels, reveals that continuous feeding on Ag-contaminated prey would resu lt in much higher metal levels in the snow crab than in the American plaice . Measurement of Ag concentrations in snow crab and American plaice from th e St. Lawrence Estuary, an environment receiving significant inputs of anth ropogenic Ag, confirmed this prediction. The similarity between laboratory- based predictions and field data strongly suggests that predation is the ma jor transfer route of Ag towards these marine benthic predators.