Seasonal Variations in Microbial Loads and Heavy Metals Concentrations in Fish from Yenagoa Metropolis, Nigeria
In Nigeria and other parts of the world, fishery products have raised serious health issues and are responsible for some of the reported deaths. In this study, the seasonal variation in microbial loads and heavy metal contents in dominant freshwater fishes from major markets in the Yenagoa metropolis was investigated. The microorganisms were isolated by using selected media and identified using Bergey’s manual. Heavy metals; Cu, Zn, Pb, and Cd concentrations were analyzed using Atomic Absorption Spectrophotometer. The isolated microorganisms include; Klebsiella species, Bacillus species, Shigella species, Pseudomonas species, Fusarium species, Mucor species, Aspergillus species, Rhizopus species, Actinomycetes species, Staphylococcus species, Chromatium species, Candida species, Trichophyton species, Listeria species, and Salmonella species. The microbial loads and isolates varied significantly (p<0.05) within seasons, with the wet season having high microbial load than the dry season. The concentrations (μg/gdw) range of the metals in the dry season are; Cu(806 – 4403), Zn (3110 – 5520) , Cd(1.40 – 5.10), Pb(7.40–14.50),while that of wet season is Cu(1280–5120) ), Zn(3170 – 6210), Cd(2.50 –6.20) and Pb(11.80 – 16.10). There was no significant difference (P > 0.01) in the concentrations of the metals among the markets and the seasons. Zn, Pb, and Cu were above the FEPA and WHO regulatory limits Cd was within the regulatory limit. Fish is one of the most affordable commodities for human for its nutritionally beneficial but can be infected with pathogenic microorganisms and contaminated with heavy metals if not properly maintained, which can pose a serious health hazard to consumers.
Keywords: Microbial loads, Heavy metal, Freshwater fish, Regulatory limit, Health hazard