ASSESSMENT OF FAECAL CONTAMINATION IN SELECTED CONCRETE AND EARTHEN PONDS STOCKED WITH CLARIAS GARIEPINUS AT FUTA OBAKEKERE

Abstract

This study was carried out to determine the levels of faecal pollution in catfish (Clarias gariepinus) and rearing waters in selected earthen and concrete ponds. Water and catfish samples were collected once in a week in the months of February, March, April, May, June and July, 2019 and they were taken in the morning and afternoon hours of the day from the selected ponds. Counts of faecal indicator bacteria in the water and catfish samples were determined using membrane filtration and pour plate methods, respectively. The physicochemical characteristics of the rearing water samples were determined using standard methods. The rate of bioaccumulation of faecal indicator bacteria was obtained by dividing the log concentration of each organism in catfish by the corresponding log concentration in the rearing waters. The results showed that the mean counts of faecal coliforms in the rearing water samples ranged from 2.85 to 3.50 log10 CFU/100ml and 2.05 to 3.00 log10 CFU/100ml in catfish samples in earthen pond, whereas in the concrete pond the mean counts of faecal coliforms in the rearing waters ranged from 2.30 to 2.80 log10 CFU/100ml and 2.25 to 3.00 log10 CFU/100ml in catfish samples. Pearson’s correlation analysis showed that faecal coliforms exhibited positive relationships with alkalinity in water samples from the earthen (r = 0.61) and concrete ponds (r = 0.62). Salmonella and faecal coliforms had the highest and least bioaccumulation in catfish raised in earthen pond respectively, whereas Salmonella and enterococci had the highest and least bioaccumulation in catfish raised in concrete pond respectively. Whilst faecal coliforms and E. coli had the highest and least counts in water samples from the earthen pond during the dry and wet months, Salmonella and E. coli had the highest and least counts in water samples from the concrete pond during the dry and wet months. The findings from this study demonstrated high levels of bacterial faecal pollution markers in water and C. gariepinus from the earthen and concrete ponds. Physicochemical characteristics of the water and seasonality played major roles in the rate of bioaccumulation of the faecal pollution markers in C. gariepinus raised in the earthen and concrete ponds.