Relationship Between Heavy Metal Concentrations in Bottom Sediments and the Clam, Galatea Paradoxa (Born 1778) from the Volta Estuary, Ghana

Abstract

This research was carried out at two locations, Ada and Aveglo at the Volta Estuary, Ghana to evaluate the importance of sediments as regulatory media in controlling the levels of four metals, Manganese (Mn), Zinc (Zn), Iron (Fe) and Mercury (Hg) in the tissues of the clam, Galatea paradoxa (Born 1778) and to investigate the possible relationships between the concentrations of the metals in the sediments and the clams. The clams were categorized into three size classes as follows: small (25 - 40 mm), medium (41 - 55 mm), and large (above 55 mm). To understand the possible relationships between the concentrations of the studied metals in the sediments and in the tissues of the three clam size classes, the monthly concentrations of the studied metals were graphed and subjected to Pearson correlation analyses (p < 0.05) to identify metal accumulation patterns and determine whether or not positive relationship patterns existed between the concentrations in the clams and sediment samples. The correlation revealed no simple linear relationships between the concentrations of four heavy metals in the clam tissues and the sediments at the two sampling stations although some distinct trends were observed. Mn concentrations in the clams and sediments from the two stations showed some clear positive relationship patterns with some increments in monthly sediment concentrations resulting in increments in clam tissue concentrations. This relationship though, was not too clear-cut.