PHYSIOLOGICAL-EFFECTS AND TISSUE ACCUMULATION OF COPPER IN FRESH-WATER RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) UNDER NORMOXIC AND HYPOXIC CONDITIONS

Rainbow trout (Oncorhynchus mykiss) were exposed to a sublethal copper concentration (0.5 ppm) for 9 days in normoXiC (P(O2) > 130 mmHg) and hypoxic (70 mmHg), hard water ([Ca2+] = 2.15 mM). There were no signs of respiratory dysfunction in any of the exposed fish. A small, transient extracellular alkalosis was induced, which was of metabolic origin in normoxia and of respiratory origin in hypoxia. During copper exposure the plasma concentrations of Na+, K+ and Ca2+ decreased. In hypoxia the decrease in [Na+] continued throughout the experiment, whereas in normoxia [Na+] recovered towards the control values. The concentration of copper increased drastically in mucous and gill, liver and kidney tissues, whereas the copper concentration of white muscle, heart, spleen and whole blood was only marginally affected by copper exposure. There were no significant differences in the degree of tissue copper accumulation between copper/normoxia- and copper/hypoxia-exposed fish.