Efeito interativo do cobre e niquel em diferentes pH em juvenis de Colossoma macropomum

Abstract

Copper (Cu) and nickel (Ni) reach aquatic ecosystems through different sources, such as mining activities, leaching of agricultural crops, and household effluents. In the environment, these metals may interact with other metals and factors, such as: pH, water hardness and others. Considering the pH variations that may occur in the environment, naturally or not, and the increasing demand for Cu and Ni in the most different industrial segments, the objective of this study was to evaluate the toxicological effects of exposure to Cu and Ni and their interaction in different pH, on biochemical and physiological markers of juveniles of Colossoma macropomum. For this, 64 juveniles of C. macropomum were exposed to four treatments, with 8 animals each: Control (without addition of metals); Cu, Ni, Cu + Ni association at pH 4 and 7, for 96 hours. In the experiment, a significant effect of pH was observed, with increased hemoglobin, catalase and lipoperoxidation and decreased activities of superoxide dismutase and acetylcholinesterase at pH7. The activity of H+-ATPase was inhibited by exposure to Cu and Cu + Ni association at pH4. The Na+/K+-ATPase activity was inhibited in the Cu, Ni, Cu + Ni treatments at pH7; the Cu + Ni association inhibited enzyme activity at both pH. For blood red series it was observed that Cu was more toxic at pH4, and Cu + Ni was more toxic at pH7. In addition, it is noted that lipoperoxidation and acetylcholinesterase activity have an inverse relationship. These results indicate that antioxidant, neurotoxic and damage responses are influenced by water pH. In addition, the inhibition of Na+/K+-ATPase activity in the treatment with the Cu + Ni association in both pH evidences an antagonistic effect of the combination of the metals.