No abstract

The aim of the present study was to establish the extent to which the outlet waters of trout farms affect the ecosystems of the Crnica and Skrapež rivers in Serbia. We monitored selected biomarkers of oxidative stress: superoxide dismutase (SOD), glutathione peroxidase (GPx) and total glutathione (GSH) in larvae of the species Ecdyonurus venosus, and simultaneously analyzed the changes in the physical and chemical parameters. The investigations were carried out in spring at four localities along the Skrapež and Crnica rivers: one upstream (the control localities), and three downstream from the fish farm outlets. On the Skrapež River, the fish farm was clearly visible and was markedly changed by the chemical parameters of the water, manifested as a decreased concentration of dissolved oxygen, increased concentrations of nitrates, nitrites, ammonium ions, total phosphorus and total organic carbon, and increased SOD and GPx activities and decreased GSH concentration in larvae from the first downstream locality as compared to the control locality. On the Crnica River, due to the high values of water flow (around 3 m 3 /s), effluents from the fish farm had no effect on the chemical parameters of the water or on the tested biomarkers.