Wetlands are considered as the final accumulation place of many toxic pollutants that enter this ecosystem through different ways and ultimately affect its balanced environment. Therefore, it is necessary to measure pollutants in water environments. Meanwhile, the selection of indicator species can provide an accurate evaluation of the ecosystem health. The aim of this work was to evaluate the accumulation of heavy metals (Zn, Cu and Pb) and antioxidant enzymes (superoxide dismutase SOD, catalase CAT and alkaline phosphatase ALP) in the liver and gill tissue of common carp caught from Bojaq wetland (Kiashahr, Gilan). In this study, 15 common carp (weight 430 g and length 30 cm) were collected from different areas of the wetland, and after separating the liver and gill tissue, the concentration of heavy metals and the activity of enzymes were measured. The results showed that the highest concentration of Zn was in liver and gill tissue, and Cu and Pb metals showed higher values, respectively. The results obtained from the enzymes activity showed that the highest levels of SOD and CAT enzymes activity were measured in the liver and gill, respectively, while higher amounts of other enzymes including CAT and ALP, were reported in the liver, and SOD and ALP were recorded in the gills. The results of the correlation test between enzymes and heavy metals showed that a significant correlation was observed between CAT enzyme and Zn in liver and between SOD enzyme and Pb in gill. The results obtained from the present study showed that the concentration of the heavy metals was not a threat to human health, but the conservation of biological species such as fish and their valuable role in the food chain in this wetland requires scientific management and continuous monitoring.
