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EFFECTS OF COPPER AND ZINC ON SMOLTIFICATION OF COHO SALMON
Citation:
Lorz, H. AND B. McPherson. EFFECTS OF COPPER AND ZINC ON SMOLTIFICATION OF COHO SALMON. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-77/032.
Description:
Many species of trout and salmon spend their early life in freshwater and then migrate to the sea. Transition from freshwater to marine existence requires physiological changes which are involved in the development of the migratory smolt stage. Sublethal exposure to pollutants in freshwater could theoretically disrupt smoltification and indirectly cause the death of smolts. In this study, exposure of smolt age coho to sublethal levels of copper in freshwater interfered with normal osmotic and ionic control in blood plasma; when the copper exposed fish were transferred to seawater the plasma osmolality and chloride concentrations increased significantly, compared to controls, and many died. These responses were attributed in part to an observed suppression of Na(+), K(+) -- activated ATPase activity in the gills of copper exposed fish. The most sensitive latent effect of exposure to sublethal levels of copper was the failure of copper exposed coho smolts to migrate successfully following release into a natural stream.