An Assessment of Bacterial and Heavy Metal Levels in Water, Sediment, and Fish Samples Collected from Kainji and Jebba Lakes, Nigeria.

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An Assessment of Bacterial and Heavy Metal Levels in Water, Sediment, and Fish Samples Collected from Kainji and Jebba Lakes, Nigeria.

Abstract: Limnology and heavy metal status of Kainji and Jebba Lakes play a crucial role in their development and management. These lakes face contamination from various sources, including animal husbandry operations, illegal mining, direct waste disposal, and other human activities. This study conducted quantitative and qualitative analyses of bacterial isolates in water, sediment, and fish samples (Clarias gariepinus and Oreochromis niloticus) from both lakes. The analysis involved primary isolation media, microbact identification kits (12A and 12B MB1132A/Australia), and molecular analysis of certain species. Additionally, concentrations of heavy metals, such as lead (Pb), copper (Cu), cadmium (Cd), chromium (Cr), and arsenic (As), in water, sediment, and fish samples were determined using an atomic absorption spectrophotometer (AA500). The physico-chemical parameters of the lake water samples were also examined, and biosorption potentials of bacterial isolates were evaluated.

The findings revealed that faecal coliform counts in Kainji Lake water samples were below the permissible limit set by the Federal Environmental Protection Agency (FEPA) at 5.0 x 102 MPN/100 mL. However, in Jebba Lake, sampling station 1 (580.83 MPN/100 mL) and station 2 (700.83 MPN/100 mL) exceeded this limit. Faecal coliform counts were higher during the wet season compared to the dry season in both lakes. Bacterial species, such as Aeromonas aquatilis strain AE 207, Burkholderia pseudomallei, Bacillus lacus AK 74, Pseudomonas donghuensis HYS, Escherichia coli, Herbaspirillum aquaticum strain IEH 4430, Alcaligenes faecalis strain Sihong 663-1, Alcaligenes faecalis strain HPRTAK198, and Oceanobacillus oncorhynchi subsp. incaldanensis strain AM-75 were isolated from the water samples in both lakes. In fish intestines and gills, Vibrio alginolyticus, Moraxella species, Escherichia hermannii, Vibrio parahaemolyticus, and Aeromonas hydrophila were identified.

Regarding heavy metal concentrations in water samples, Cu, Cr, and As were below the permissible limit (2.0, 0.05, and 0.1 mg/L, respectively), while Cd concentrations were higher (0.09 and 0.17 mg/L for Kainji and Jebba Lakes, respectively) than the FEPA limit of 0.01 mg/L. Pb concentrations in certain sample stations exceeded the permissible limit of 0.05 mg/L. Heavy metal concentrations in water samples were higher during the wet season compared to the dry season. However, fish muscles of Oreochromis niloticus and Clarias gariepinus in both lakes had low heavy metal concentrations.

The sediment from both lakes had heavy metal concentrations below the threshold effect concentration (TEC). Physicochemical qualities of all examined parameters in both lakes were found to be within acceptable limits favorable for aquatic life. Bacillus lacus strain AK 74 exhibited high biosorption potential for Pb (99.0%), Cu (98.0%), and Cr (96.5%) within 28 days at an initial concentration of 1.0 parts per million.

The results indicate that Kainji and Jebba Lakes are facing pollution due to increasing human activities. Therefore, best practices should be adopted in mining and other human activities to mitigate the high heavy metal concentrations found in some sample stations.

An Assessment of Bacterial and Heavy Metal Levels in Water Sediment and Fish Samples Collected from Kainji and Jebba Lakes Nigeria.

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