Anthropogenic radionuclides bioaccumulation in Antarctic marine fauna and its ecological relevance

The paucity of investigations on the presence of artificial radionuclides a nd their bioaccumulation in Antarctic fauna is due to the erroneous belief that this area is pristine. We report evidence that significant levels of t he artificial radionuclides Sr-90, Cs-137, Am-241 and plutonium isotopes ca n be found in sponges, bivalves, krill and demersal fish fauna of Terra Nov a Bay (Ross Sea), sometimes with a seasonal pattern. Increasing concentrati ons of Cs-137 were detected in the bivalve Adamussium colbecki (Antarctic s callop) during austral summer months, as a result of major trophic activity and changes in metabolic rates. Bioconcentration factors for artificial ra dionuclides in different Antarctic species are presented and discussed in r elation to their different trophic strategies. Unexpectedly high radiocesiu m bioconcentration factors determined in bivalves suggested the particular role played by filter feeding in bioaccumulation, particularly in summer wh en radionuclide bioavailability is enhanced. The feeding preference of the trematomiid fish Trematomus bernacchii for the scallop A. colbecki is confi rmed, not only by fish gut content analyses, but also through radiometric r esults. Transuranics bioaccumulation by sensitive species allowed some inte resting comparisons on the different plutonium contamination of the souther n hemisphere with respect to the northern one.