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LEVEL AND EXTENT OF MERCURY CONTAMINATION IN OREGON, USA, LOTIC FISH
Citation:
Peterson, S A., A. T. Herlihy, R. M. Hughes, K. L. Motter, AND J. M. Robbins. LEVEL AND EXTENT OF MERCURY CONTAMINATION IN OREGON, USA, LOTIC FISH. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. SETAC Press, Pensacola, FL, 21(10):2157-2164, (2002).
Description:
Because of growing concern with widespread mercury contamination of fish tissue, we sampled 154 streams and rivers throughout Oregon using a probability design. To maximize the sample size we took samples of small and large fish, where possible, from wadeable streams and boatable rivers. The two sample types were analyzed by piscivore and invertivore trophic guilds and by specific fish taxon and related to western and eastern ecoregions of Oregon. We found no significant relationship between fish taxa, large of small, and ecoregion. However, the relationship between fish tissue mercury concentration and fish length was highly significant for both invertivores and piscivores. Analytical results were inferred to Oregon aggregate ecoregions and to the length of streams/rivers that exceeded critical threshold wet weight mercury values for piscivorous birds (0.02 ug Hg/g), mustelids (0.1 ug Hg/g), and humans (0.2 ug Hg/g). We found that for bass and pikeminnow 100% of assessed streams exceeded the avian threshold. For the same two species, 70.3% and 96.3% of assessed streams exceeded the mustelid threshold. Pikeminnow also exceeded the human health threshold in 86.8% of assessed stream length. Trout exceeded the avian, mustelid, and human health thresholds in 82.0%, 15.3%, and 3.8% of assessed stream lengths, respectively. Mercury concentrations in both big and small fish were greater in western Oregon than in eastern Oregon. It is speculated that this might be due to greater precipitation in the west and to the atmospheric transport of air borne contaminants from eastern Asia to the coast of Oregon.