Integrated laboratory and field assessments of heavy metals accumulation in edible periwinkle, Tympanotonus fuscatus var radula (L.)

Laboratory and field bioaccumulation experiments were employed in assessing the impact of metal-laden effluents on the tissue concentrations of heavy metals in edible periwinkle, Tympanotonus fuscatus, in Lagos Lagoon. The field experiments showed that Zn and Pb accumulated in T. fuscatus collected from impacted stations were found to be about 10 times higher than the concentrations detected in control animals. A similar observation was also recorded in the laboratory experiment whereby the concentrations of the metals accumulated in whole body tissues of exposed animals were about 3–4 times higher than the concentrations detected in control animals. With respect to accumulation of Cu in T. fuscatus, the pattern was neither regular nor consistent throughout the duration of the experiment, under both the field and the laboratory conditions. The termination of metal-laden effluent discharges into the experimental creek, after 150 days of contamination, resulted in a rapid and significant decline in the concentrations of the metals detected in the sediment. However, the concentrations of metals accumulated in tissues of the periwinkles remained high. The significance of the observations for heavy metal pollution management in aquatic ecosystems and for consumer safety are discussed.