Evaluation of Heavy Metal Contents as Pollution Biomaskers in Fishes of Wasai Reservoir, Kano State-Nigeria

The study was carried out to assess heavy metal concentrations in water, gills and liver of Tilapia zilli sampled from Wasai Reservoir from January 2019 to June 2020, with the aim of predicting health risk to the consumers. Sampling stations were selected based on variation of human activities around the water body. Levels of metals were determined using Microwave Plasma Emission Spectroscopy (MP-AES). The results indicated that metal concentrations in water followed the following order: Zinc (2.55 mg/L) > Chromium (0.067 mg/L) > Lead (0.058 mg/L) > Cadmium (0.031 mg/L), with Arsenic undetected. The Bioaccumulation Factor (BAF) showed that heavy metal accumulation in fish tissues was highest for Zn, followed by Pb, Cr, Cu, Cd, and As. Significant differences (P<0.05) were observed in the heavy metal concentrations across sampling stations, months, and seasons, except for Cr and Cd, which did not show significant variations (P>0.05). Fish tissue analysis revealed significant increases (P<0.05) in the gills (Cu > Pb > Zn > Cr > As > Cd) and liver (Cu > Pb > Zn > Cd > Cr > As). Pearson’s correlation coefficient indicated strong positive correlations for Zn, Cr, Cd, and Pb (P<0.01), while negative correlations were observed for Cd and Cu (P<0.01). The study concluded that heavy metal pollution significantly affected fish physiology and water quality in the reservoir, primarily due to anthropogenic activities. It recommends the implementation of proper reservoir management systems to conserve this vital ecosystem and prevent its long-term deterioration.