Proximate Composition and Heavy Metal Content of Three Class Sizes of the Clam Senilia senilis from the Andoni River, Niger Delta, Nigeria

The proximate composition and heavy metal content of the clam Senilia senilis from the Andoni River was investigated. Samples were categorized into three class sizes: small (< 30 mm), medium (30-50 mm), and large (> 50 mm) each with 10 sampling units for each class size. Differences across class size were significant for carbohydrate, protein, lipid, and fiber contents but not ash and moisture contents. Effect of class size on proximate composition of soft tissues of clams was more pronounced in carbohydrate and lipid contents relative to protein and fiber contents, with mean values of carbohydrate and lipid generally higher in largesized clams compared to small-sized and medium-sized clams. Among the heavy metals, variations in mean Cu and Zn levels in S. senilis were minimal compared to Cd and Pb in which large-sized clams also had higher mean values than small-sized clams. The chances of uptake of Cd and Pb in higher trophic levels of the food chain are higher following consumption of large-sized clams, since the concentrations of these heavy metals appear to be higher in large-sized clams compared to small-sized and medium-sized individuals.