Linking Metal Contamination to Catalase Activity in Labeo rohita: Insights from the Indus River of Pakistan

Abstract

This study examined catalase enzyme activity in relation to metal pollutant bioaccumulation in various body parts of Labeo rohita collected from different fishing sites along the Indus River, including Sukkur Barrage (SB), Guddu Barrage (GB), and Kotri Barrage (KB). A total of ten fish samples were captured from each site. The selected fish were dissected on-site to collect the liver, gills, muscle tissue, and kidneys. The extracted organs were stored in labeled polythene bags placed in crushed ice and transported to the laboratory for further analysis. Water samples from each site were also collected to measure the concentrations of heavy metals, including nickel (Ni), lead (Pb), cadmium (Cd), cobalt (Co), and mercury (Hg). The collected organ samples were prepared to assess catalase enzyme activity using a spectrophotometer at 240 nm. Both water and tissue samples were analyzed for metal content following standard procedures. Catalase activity in the liver, kidney, gills, and muscle tissues was highest in samples from SB, followed by GB, and lowest in KB. The concentration of heavy metals in both water and fish organs followed the order: Ni > Pb > Co > Cd > Hg. The findings suggest that measuring antioxidant enzyme activity and heavy metal bioaccumulation in fish tissues can serve as an early indicator of environmental pollution, helping to detect contamination levels before they reach thresholds that could harm aquatic life and disrupt ecosystem health. Monitoring enzyme activity in local fish populations can thus provide valuable insights into the ecological status of riverine systems.