Seasonal Variability of Heavy Metals Concentration in Fish Species Organs From Upper River Benue, Yola- Adamawa State

Seasonal Variability of Heavy metal in Fish species organs in Upper River in Yola Adamawa State was investigated from May 2018 to April 2019. Fish species of commercial importance (Auchenoglanis occidentalis, Oreochromis niloticus and Clarias gariepinus) were sampled monthly in triplicate for the twelve months. The entire fish samples (Auchenoglanis occidentalis, Oreochromis niloticus and Clarias gariepinus) were separated and scales were removed (for those with scales) and washed with running water before dissecting with sterile scissors to remove gills, livers and muscles. Wet digestion technique was used as described by AOAC (2002). Seasonal variability of Heavy metals in fish species Organs were determined by comparing levels obtained in Wet season with the level obtained in Dry season. Data obtained in this study were subjected to descriptive statistics to establish means, standard errors. One way analysis of variance (ANOVA) was used to determine the mean significant seasonal variation (at 0.05) of heavy metals in the fishes from the sampling stations using Statistical Package for Scientists and Engineers (Statistix 9.0). All the heavy metals investigated were present in fish organs except cadmium and chromium which were also below detection level. The mean values of heavy metals obtained in this study revealed that, metals accumulate more in the organs of fish species in dry season than in the wet season. The trend of the accumulation of metal in the study was Zn>Cu>Pb>Ni. The trend of the accumulation of metal in the organs of fish species in this study was liver>liver>flesh>liver of C.gariepinue>C.gariepinue>O.niloticus> C.gariepinue Heavy metals Cu, Ni, Pb and Zn recorded their highest values (1.27±0.18mg/kg, 0.31±0.13mg/kg, 0.94±0.05mg/kg and 1.64±0.14mg/kg) in dry season (April, March, December and January) respectively, when compared with wet season in fish of Upper River Benue