Bioaccumulation of some heavy metals in organs of Heterotis niloticus and Tilapia zillii in Maladumba Wetland, Misau Lga, Bauchi north-eastern Nigeria

Abstract

Fish is a highly valued source of protein, prized for its exceptional quality, polyunsaturated fatty acids, vitamin B, and other essential nutrients. This study, conducted in Maladumba Wetland, Misau Local Government Area of Bauchi State, northeastern Nigeria, aimed to assess the concentration of heavy metals (lead, chromium, cadmium, and copper) examine the spatio-temporal dynamics of physicochemical parameters in the wetland and evaluate the accumulation of these heavy metals in the kidney, liver, flesh, and gills of two commercially important fish species, Heterotis niloticus (African bony tongue) and Tilapia zillii (Mango Fish). Water quality parameters such as pH, dissolved oxygen (DO), temperature, etc. were measured. Data were analyzed using ANOVA, Tukey’s test, and Pearson’s correlation. The mean physicochemical parameters recorded in water were temperature (23.83 ± 0.94°C), pH (6.61 ± 0.17), DO (4.63 ± 0.11 mg/L), BOD (28.41 ± 0.11 mg/L), COD (183.91 ± 3.01 mg/L), and turbidity (28.17 ± 0.17 NTU). The mean concentrations (mg/kg) of heavy metals in Heterotis niloticus were cadmium (0.93 ± 0.01), chromium (5.01 ± 0.17), copper (7.31 ± 0.04), and lead (7.15 ± 0.04). In Tilapia zillii, the concentrations were cadmium (3.00 ± 0.20), chromium (5.00 ± 0.17), copper (9.95 ± 0.03), and lead (6.80 ± 0.17). Copper was the most abundant heavy metal in both fish species, while cadmium was the least. The study highlighted the risks associated with heavy metal contamination in the Maladumba Wetland and the potential dangers of consuming contaminated fish. Further research is recommended to explore the human health implications of heavy metal bioaccumulation in fish from this wetland.