Bacteriological and heavy metal status of water and fish samples from Jebba Lake – Nigeria

Abstract

Quantitative and qualitative analysis of bacterial isolates in water and fish samples (Oreochromis niloticus and Clarias gariepinus) from Jebba Lake were carried out using primary isolation media and microbact identification kits. The concentration of heavy metals, Lead (Pb), Copper (Cu), Cadmium (Cd), Chromium (Cr) and Arsenic (As) were determined using Atomic Absorption Spectrophotometer (AAS). Samples were collected from five (5) different stations. Station Jl.1 and Jl.2 are located at the upper course of the lake and were characterized by high human activities (washing, bathing, mining and animal husbandry operations) especially in sample station Jl.2. Sample station Jl.3 has low human activities, however it has a tributary with high mining activities. Station Jl.4 has high domestic washings but low animal husbandry operation and low mining activities. Station Jl.5 has low domestic washings, low animal husbandry operation and low mining activities. Mean faecal coliform count of sample station Jl.1 (580.83 CFU/100ml) and station Jl.2 (700.83 CFU/100ml) were above maximum permissible limit for Federal Environmental Protection Agency (FEPA). Faecal coliform count of sample stations Jl.3, Jl.4 and Jl.5 were below maximum permissible limit. Maximum faecal coliform count during the wet season was 1600.00 CFU/100ml, while the maximum count during the dry season was 920.00 CFU/100ml. Bacterial species such as Aeromonas caviae, Aeromonas hydrophila, Pseudomonas fluorescens – 25, Escherichia coli, Moraxella species, Mannheimia (pasturella) haemolytica, Pseudomonas aeruginosa, Pseudomonas fluorescens – 35, Escherichia hermannii were found in water samples and species such as Vibrio alginolyticus, Moraxella species, Escherichia hermannii, Vibrio parahaemolyticus, Aeromonas hydrophila were isolated from fish intestines and gills. Concentration of Cu, Cr and As in water was observed to be within permissible limit but the concentration of Pb and Cd were above tolerable limit. In fish organs, the concentration of heavy metals were within permissible limit except that of Pb and As in Oreochromis niloticus fish intestines (ONFI) (0.38±0.00 and 0.03±0.00 respectively) and Clarias gariepinus fish intestines (CGFI) (0.40±0.00 and 0.03±0.01 respectively) which were above maximum permissible limit by standard organizations.

Key words: Jebba Lake, water, fish, Oreochromis niloticus, Clarias gariepinus, bacteria, heavy metals