Liver Stress Biomarkers as Indicators of Water Pollution in Oreochromis mossumbicus-Tilapia Fish from Three Lakes around Bangalore: Preliminary Report

Toxic chemicals discharged into aquatic environments enter the food chain and induce multiple adverse effects on aquatic organisms and human health. The use of biomarkers provides preliminary information which, once validated through laboratory studies can provide direct measures of actual effect of heavy metals on biota, especially fish thereby overcoming large areas of uncertainty implicit in normal risk assessments. Heavy metals accumulated in the tissues of aquatic organisms may catalyze reaction that generates reactive oxygen species (ROS) which may lead to oxidative stress in the exposed organisms. Therefore, antioxidant defense systems are increasingly studied as potential biochemical biomarkers for environmental monitoring systems. Oreochromis species are widely consumed and serve as important fishery resources. In the present study, bioaccumulation of metals in Oreochromis mossambicus collected from three lakes around Bangalore was assessed through analysis of antioxidant enzyme activity and lipid peroxidation as early biological markers of environmental stress. The results suggest chloride values in the range of 161.14 mg/L to 201 mg/L and phosphates 2.23 mg/l to 165mg/l from across sampling sites. Elevated chlorine levels in Hebbal Lake appear to contribute to physiological stress, while high phosphate levels suggest reduced glucose oxidation in fish. Biological oxygen demand (BOD) ranged from 15 mg/L to 40 mg/L, with higher values in Hebbal and Kanakapura lakes indicating organic and effluent pollution. Increased liver marker enzyme activity suggests toxic effects of metals and minerals on hepatic function. Overall, the findings highlight the detrimental impact of water pollutants on lake ecosystems and aquatic fauna. Liver enzyme biomarkers may serve as effective early indicators of toxicity and provide a practical model for lake pollution monitoring and fishery management.