Microbial diversity, heavy metals and hydrocarbons concentration in some fish species from Qua Iboe River Estuary, Akwa Ibom State, Nigeria

The diversity of fish gut microflora, heavy metals and hydrocarbon concentration of two fish species (Pseudotolithus typus and Chrysichthys nigrodigitatus) from Qua Iboe River Estuary was investigated. The total heterotrophic bacteria and fungi as well as hydrocarbon utilizing bacteria and fungi in the fish guts were abundant and ranged from 6.87 to 7.57logcfu/g, 5.68 to 5.80logcfu/g, 5.42 to 5.48 logcfu/g and 2.76 to 3.40logcfu/g respectively. The microbial counts varied among the fish species. Proteus, Bacillus, Staphylococcus, Salmonella, Vibrio, Escherichia, Lactobacillus, Micrococcus and Enterobacter were the different bacterial genera encountered in the study while Penicillium sp., Aspergillus niger., Fusarium sp. and Mucor sp were the fungal species identified. The analysis of the metals showed that Zn, Cu and Fe with concentrations ranging from 0.51 to 4.20mg/kg, 3.51 to 4.11 and 1.19 to 2.04mg/kg respectively were the most abundant and were higher than the maximum permissible limits set by FEPA/WHO. The total mean PAHs and BTEX concentrations were 62.18±4.72 ng/g and 43.67±4.06 ng/g for C. nigrodigitatus, 123.52±3.11 ng/g and 211.68±3.53 ng/g for P. typus respectively which were higher than acceptable limits. Findings from this study shows poor microbiological quality thus the need for continuous monitoring of our natural waters and proper processing of aquatic foods as the present situation portends a potential concern for ecological risk.