Heavy metals bioaccumulation and subsequent multiple biomarkers based appraisal of toxicity in the critically endangered Tor putitora

The construction of hydropower projects discharges effluents to aquatic bodies. The effluents consist of different chemicals including heavy metals. The current study assessed the effects of effluents discharged from an under-construction hydropower project on the bioaccumulation of heavy metals in the tissues of critically endangered Tor putitora (Hamilton, 1822) in the river Panjkora. The subsequent toxic impacts of higher bioaccumulation of heavy metals on different biochemical, hematological, and serum biochemical profiles were also studied. Different biochemical changes were observed in the tissues of T. putitora including stress biomarkers such as reactive oxygen species, lipid peroxidation, total protein contents, antioxidant enzymes (peroxidase, superoxide dismutase, catalase, reduced glutathione, glutathione reductase, and glutathione-s-transferase), acetylcholinesterase, and whole-body cortisol. The hematotoxic effects were also observed as the count of red blood cells, hematocrit, and hemoglobin decreased whereas the count of white blood cells increased. Serum biochemical analysis revealed that cholesterol, urea, total bilirubin, and glucose concentration increased, whereas total proteins and albumin decreased with an increase in the concentration of heavy metals across the sampling sites. The fish from the river was found to be under severe stress as compared to the fish from the reference site. To mitigate the current scenario, stocking fish in an appropriate amount is suggested. The fish diversity and water quality should be assessed at regular intervals to avoid further deterioration and diversity loss. The safety and conservation of wild fisheries should be ensured by implementing strict environmental protection and fishing laws. •Hydropower projects discharge toxic effluents and deteriorate the rivers ecosystem.•Tor putitora in polluted rivers bioaccumulate toxic metals in several tissues.•Heavy metals cause stress and compromise the overall wellbeing of the Tor putitora.