Heavy Metals Accumulation in Marine Edible Molluscs, Timsah Lake, Suez Canal, Egypt

Aims: to investigate and to compare the variation of the bioaccumulation of heavy metals (Cr, Cd, Fe, Mn, Pb and Zn) by two different molluscs species and also heavy metal concentration in sea water and sediment in Timsah Lake-Suez Canal. And finally to study the correlation between metal concentrations in different size classes of each molluscan species. Study Design: Levels of the heavy metals (Cr), (Cu), (Fe),(Mn), (Pb), and (Zn) were determined in water, sediment and soft tissues of the gastropod Thais carinifera and the bivalve Venerupis aureus in Timsah LakeSuez Canal. Place and Duration of Study: Marine Sciences Department, Faculty of Science, Suez Canal University, Ismailia, Marine Sciences Department, Faculty of Science, Port Said University, Egypt, in April 2013. Methodology: Surface sediment sample (15 cm), Sample of water (0.5 m depth) and 244 molluscan specimens (65 gastropods and 179 bivalves) covering a wide size-range was collected from sampling site. Results: The concentrations of heavy metals in water were 0.5, 0.9, 2.5, 0.22, 0.41and 0.25 for Cr, Cu, Fe, Mn, Pb and Zn μg L-1, respectively. The corresponding concentration values in the sediments 12.8, 10.2, 18.8, 14.5, 12 and 45 μg g-1 dry weight for Cr, Cu, Fe, Mn, Pb and Zn, respectively. While the heavy metals concentrated in molluscs was 17.5, 17.4, 933.5, 20.9, 30.25 and 89 (μg g-1 dry weight) for Cr, Cu, Fe, Mn, Pb and Zn, respectively. Conclusion: The accumulation of heavy metals is predominant in molluscs than in sediment and water. The gastropod (t. Carinifera) and the bivalve (v. Aureus) accumulate different amount of metals in their tissues. The accumulation of metals was more pronounced in v. Aureus than t. Carinifera. A positive correlation between metal concentration and size of the gastropod t. Carinifera was found, which means that the largest individuals contained the highest levels of metals. While metal concentrations increased with length in v. Aureus.