Publication Details
Abstract
Objective: The present study aims to examine the individual and combined sublethal effects of these two elements (Lead (Pb) and Cadmium (Cd)) on the endemic Binni fish (Mesopotamichthys sharpeyi). Method: A multi-tiered approach using biomarkers was applied after 60-days of laboratory exposure to environmentally relevant concentrations of Pb (50 and 100 µg/L), Cd (5 and 10 µg/L) and low-concentration mixture (50 µg/L Pb + 5 µg/L Cd). Results: Results indicated strong bioaccumulation of the two metals, in a dose-dependent manner, with liver being the main target organ, accumulating metal concentrations many orders of magnitude above those found in muscle tissue. This build-up led to a high degree of hepatic oxidative stress as indicated by increased levels of lipid peroxidation (malondialdehyde) and also a profound decrease in the key antioxidant enzymes catalase and superoxide dismutase. The biochemical disturbances were the most severe with the exposure mixture, suggesting a synergistic toxic effect. These changes occurred in the sub-cellular level and were directly linked to the extensive histopathological damage. Novelty: The results show that current environmental levels of Pb and Cd in the Tigris River are potentially very harmful to the health of M. sharpeyi, and have clear implications for the ecological integrity of the aquatic ecosystem, and potentially human health via the food chain.