Biodilution and biomagnification of silver in Lake Moreno, Patagonia, Argentina

REVENGA, J.; CAMPBELL, L.; KYSER, K; ARRIBÉRE, M.; ARCAGNI, M; RIZZO, A.; RIBEIRO GUEVARA, S.

La Malbaie, Canada

Workshop; 36th Aquatic Toxicity Workshop; 2009

Silver (Ag) concentration in sediments and biota from Lake Moreno, Patagonia, Argentina, have been found to be enriched in association with human population growth. Fish liver Ag concentrations are among the highest ever reported globally. The goal of this study was to analyse the trophic transfer of Ag in Lake Moreno in Nahuel Huapi National Park, in light of the ecotoxicological risk. During 2001-2008 the biota of Lake Moreno was sampled, and stable N and C isotopes were used to characterize food web transfer of Ag. There was Ag biodilution between phytoplankton and zooplankton. In addition, no toxic effects of diet borne Ag was found in relation to [Na] in zooplankton. Interestingly, brook trout (Salvelinus fontinalis) showed hepatic biomagnification, although no biomagnification trends were detected for muscle tissue samples. When whole biota was analysed, significant Ag biomagnification was observed for the whole food web. Both Ag biodilution and biomagnification operates simultaneously in Lake Moreno. Biodilution in the phytoplankton and zooplankton food decreases the toxicological risk for organisms in planktonic food webs, whereas biomagnification in fish livers and whole biota increases the toxicological risk to terrestrial and avian predators such as gulls. However, human risk is very low due to the absence of fish liver consumption in the region