Bioaccumulation of copper in selected amphibians in relation to water and sediment quality at Head Balloki, River Ravi

Freshwater ecosystems are increasingly threatened by heavy metal pollution, particularly in developing regions where industrial waste discharge is poorly regulated. This study investigates the bioaccumulation of copper (Cu) in three amphibian species viz., Hoplobatrachus tigerinus, Bufo stomaticus, and Euphlyctis cyanophlyctis, in relation to copper concentrations in water and sediment at Head Balloki, a key hydrological site on the River Ravi, Punjab, Pakistan. Sampling was conducted from January to April 2024. Water and sediment samples were analyzed for copper content, and amphibian tissues (liver, muscle, and skin) were examined using atomic absorption spectrophotometry. Results revealed elevated levels of copper in both environmental and biological samples. Water samples showed higher concentrations upstream compared to downstream, with the highest values recorded in April. Sediment analysis indicated peak copper accumulation in February. Among the amphibians, H. tigerinus exhibited the highest tissue concentrations, particularly in the liver (6.17 ± 0.98 µg/g), followed by B. stomaticus and E. cyanophlyctis. Liver tissues consistently accumulated more copper than muscle or skin, reflecting organ-specific detoxification roles. This study highlights the ecological vulnerability of amphibians in the River Ravi basin and suggests that copper contamination poses a significant threat to aquatic biodiversity. Given the central role amphibians play in ecosystem functioning and their sensitivity to environmental changes, the study serves as an urgent call for targeted environmental policy, pollution control, and continued ecological surveillance in Pakistan’s freshwater systems.