Elevated levels of heavy metals in the catfish Synodontis clarias can be a good indication of pollution of an aquatic ecosystem due to anthropogenic influence. The concentrations of Zn, Cd, Pb, Mn and Ni were determined in Synodontis clarias caught along a section of Taylor Creek and its associated tributaries. Samples were collected bimonthly between July 1999 and June 2000 in five stations. The metals: Zn, Cd, Ni, Pb and Mn were recorded in appreciable quantities, signifying their bioavailability. The levels of Zn, Cd, Ni, Pb and Mn may have obvious health implications on the rural communities that depend on fish species as fish supplement in view of its rich protein content and its bio-economic value. Generally, the sources of the metals in the catfish appear to be point and diffuse which include rural and agricultural runoff sources in the catchments area. However, the presence of an oil industry activity (Etelebou oil field and flow station) in one of its tributaries appears to be the major point source of the metal pollutants.

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The aim of this study was to assess accumulation of heavy metals in tissues of Periwinkle (Tympanotonus fuscatus var radula (L.) obtained from Azuabie creek using Okujagu creek as control location. Fifty samples were collected from each site for three months (October-December 2015). Atomic Absorption Spectrophotometric technique was used in heavy metal analysis. Mean metal concentrations in sediments were as follows Zn: 178.08 mgkg -1 ; Cd: 0.3 mgkg -1 ; Cr: 14.27 mgkg -1 and Pb: 18.75 mgkg -1 . While those in Periwinkle tissue with biosediment accumulation factor (BAF) in parenthesis were thus Zn: 24.42 mgkg -1 (0.137); Cd: 0.02 mgkg -1 (0.067); Cr: 1.57 mgkg -1 (0.11) and Pb 0.01 mgkg -1 0.001). The result of BAF of metals indicated low values which could be related to assimilation and excretion rate of heavy metals in the organisms examined. Variations in the concentration of Zn in the gastropod tissues showed significant difference (p<0.01) between sites, likewise, Cr (p<0.001) and Cd (p<0.05). In conclusion, comparison between the two creeks showed that tissue samples from St1, St2 and St3 (Azuabie creek) had higher concentration of metals in relation to the control station (Okujagu creek) indicating potentials for accumulation, mainly due to differences in anthropogenic activities. Cr, Cd and Pb concentrations in tissue had mean values less than the recommended limits in seafood by FAO/WHO however, regular monitoring is required to observe perturbations.

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