Abstract

The study was conducted to evaluate the impact of effluents containing heavy metals on the water quality and physiological health of Channa striata brooders. It focused on changes in bioindices and biochemical biomarkers, comprising antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) and metallothionein (MT) protein levels. Hormonal parameters, including testosterone and estradiol, along with the expression of vitellogenin (Vtg) and estrogen receptor alpha (ERα), were assessed in fish collected from two sites on the River Ganga, Narora and Kanpur, and a reference site, KGF at Aligarh. Kanpur (Jajmau) site receives effluents primarily from tannery industries and domestic sewage, while the Narora stretch is influenced by agricultural runoff as well as industrial discharges from the nearby lock-manufacturing units. Elevated concentrations of iron, nickel, chromium, cadmium, and lead at both sites due to contamination resulted in metal bioaccumulation in tissues (muscle, liver, and gonads). The liver showed the most pronounced site-specific variations in both sexes, including reductions in bioindices values and alterations in antioxidant enzyme activities, particularly at Kanpur. MT levels increased consistently from KGF to Kanpur (Jajmau) in both liver and gonads of brooders. Testosterone and estradiol levels declined in males and females, respectively, along the pollution gradient. In addition, site-specific expression patterns of Vtg and ERα genes revealed compromised reproductive health. Both genes were significantly upregulated, indicating metal-induced transcriptional activation.

Key words: Heavy metals, Bioaccumulation, Bio indices, Antioxidant enzymes, Metallothionein, Testosterone, Estradiol, Vtg, ERα