EVALUATION OF BACTERIAL AND HEAVY METAL STATUS OF WATER, SEDIMENT AND FISH SAMPLES FROM KAINJI AND JEBBA LAKES, NIGERIA

Abstract

Information on limnology and status of heavy metals of Kainji and Jebba Lakes are key in the development and management of the Lakes. These Lakes receive organic and inorganic wastes through animal husbandry operations, illegal mining activities, direct waste disposal and other human activities. Quantitative and qualitative analyses of bacterial isolates in water, sediment and fish samples (Clarias gariepinus and Oreochromis niloticus) from Kainji and Jebba Lakes were carried out using primary isolation media, microbact identification kits (12A and 12B MB1132A/Ausralia) and molecular analysis of some species. Concentrations of heavy metals: lead (Pb), copper (Cu), cadmium (Cd), chromium (Cr) and arsenic (As) in water, sediment and fish samples were determined using atomic absorption spectrophotometer (AA500). Physico-chemical parameters of the Lake water samples were determined. Biosorption potentials of bacterial isolates were also evaluated. Faecal coliform counts of water samples from Kainji Lake were below maximum permissible limit of 5.0 x 102 MPN/100 mL while sampling station 1 (580.83 MPN/100 ml) and 2 (700.83 MPN/100 ml) of Jebba Lake were above maximum permissible limit of 5.0 x 102 MPN/100 mL according to Federal Environmental Protection Agency (FEPA). Faecal coliform counts during wet season were higher than those obtained during 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, Oceanobacillus oncorhynchi subsp. incaldanensis strain AM-75 were isolated from the water samples in both Lakes. Vibrio alginolyticus, Moraxella species, Escherichia hermannii, Vibrio parahaemolyticus, Aeromonas hydrophila were isolated from fish intestines and gills. Concentrations of Cu, Cr and As in water samples were below maximum permissible limit (2.0, 0.05 and 0.1 mg/L respectively). However, the concentrations of Cd were higher (0.09 and 0.17 mg/L for Kainji and Jebba Lakes respectively) than the maximum permissible limit of 0.01 mg/L according to Federal Environmental Protection Agency (FEPA). Concentrations of Pb in sample stations; Kl.2 (0.082 mg/L), Kl.3 (0.078 mg/L), Kl.4 (0.057 mg/L), Jl.1 (0.066 mg/L), Jl.2 (0.380 mg/L), Jl.3 (0.141 mg/L) and Jl.5 (0.064 mg/L) were above maximum permissible limit of 0.05 mg/ L. The concentrations of heavy metals in the water samples were higher during the wet season compared to the dry season. In fish samples, the concentrations of Pb in Oreochromis niloticus fish intestines (ONFI) and Clarias gariepinus fish intestines (CGFI) were above maximum permissible limit. Fish muscles of Oreochromis niloticus and Clarias gariepinus in both Lakes had low heavy metal concentrations. Heavy metal concentrations in sediment from the Lakes were found to be below threshold effect concentration (TEC). Physicochemical qualities of all the parameters examined in both Lakes were found to be within acceptable limit that is favourable for aquatic lives. Biosorption potentials of bacterial isolates revealed that Bacillus lacus strain AK 74 had high potential to biosorp Pb (99.0 %), Cu (98.0 %) and Cr (96.5 %) within 28 days at initial concentration of 1.0 parts per million. Kainji and Jebba Lakes are experiencing pollution due to increasing human activities. The results of this study showed high heavy metal concentrations in some of the sample stations; hence human activities such as mining in these stations should follow best practices