Biochemical, haematological and oxidative stress responses of common carp (Cyprinus carpio L.) after sub-chronic exposure to copper

The aim of the present study was to investigate the impact of copper-based pesticides (at concentrations of copper of 20, 30, 40 and 70 µg/l) on one-year-old common carp (Cyprinus carpio L.) during 28 days of exposure. Abnormal behaviour was observed in fish exposed to 70 µg/lfrom Day14. Histological alterations were noticed only in liver in the groups exposed to 40 and 70 µg/l.Significant changes (P ˂ 0.05) in almost all haematological indices were found, especially in the group exposed to the highest concentration of copper (70 µg/l). Biochemical analysis revealed various significant (P ˂ 0.05) differences among the tested groups. Significant differences in copper tissue concentration (P ˂ 0.05) among groups were found in liver, gills and kidney. Among antioxidative enzymes, significant changes were revealed mainly in catalase and glutathione-S-transferase activity (P ˂ 0.05). In gills, metallothionein content increased significantly (P ˂ 0.05) in the group exposed to the highest copper concentration (70 µg/l) compared with the other tested groups, including the control. A significant (P ˂ 0.05) change in total glutathione content was recorded in liver and gills, although the reduced/oxidised ratio was not affected. Oxidative damage to lipids increased significantly (P ˂ 0.05) with increasing copper concentration in liver and kidney. The results demonstrate the deleterious influence of copper on common carp even at low, environmentally relevant concentrations.