Seasonal changes in oxidant and antioxidant biomarkers in liver and muscle of common carp (Cyprinus carpio) in Atatürk Dam Lake

Seasonal investigations were conducted on 640 Cyprinus carpio specimens obtained through commercial fishing at four different stations (Gerger, Sitilce, Hosirge, and Samsat) in the Atatürk Dam Lake. MDA (malondialdehyde) levels were measured in the liver and muscle tissues of male and female fish; the results revealed a significant increase in MDA levels at stations exposed to point-source discharge. This indicates that pollution-induced oxidative stress in fish varies significantly across seasonal and regional scales. Among the stations compared, the lowest MDA values were detected in fish tissues from the Gerger station, while the highest values were recorded at the Sitilce and Hosirge stations. Analysis of SOD, GSH-Px, and GSH values across all stations showed that these parameters fluctuated in correlation with MDA levels thereby maintaining the oxidant-antioxidant balance. This study investigated seasonal and spatial variations in oxidative stress biomarkers in common carp (Cyprinus carpio) collected from four stations in Atatürk Dam Lake. A total of 640 specimens were analyzed for malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and reduced glutathione (GSH) levels in liver and muscle tissues. Results showed that MDA levels were significantly higher in fish collected from Sitilce and Hosirge stations, indicating elevated lipid peroxidation associated with point-source pollution. In contrast, the lowest MDA levels were observed at the reference station, Gerger. Antioxidant enzyme activities (SOD, GSH-Px, and GSH) exhibited tissue-, season-, and site-dependent variations, suggesting adaptive responses to oxidative stress. Overall, the findings demonstrate that anthropogenic pressures in Atatürk Dam Lake significantly alter the oxidant–antioxidant balance in fish, highlighting the usefulness of these biomarkers for environmental monitoring.