Vol.4 No.3 – 4 : Marine pollution by some heavy metals and physiological response of Ruditapes decussatus

By : G.M El Khodary, E.H Radwan, M.M El Ghazaly and D. El Bahnasawy

Damanhour University, Faculty of Science, Zoology department, Egypt

Abstract

Bivalves can accumulate toxicants such as heavy metals in their tissues, for this reason they are considered as a good bio-indicators for water quality. The risk is increased due to eating these clams raw or lightly cooked. The aim of this study is to determine the concentration of some selected metals (Cu, Zn, Mn, Cd, and Pb) in the soft tissue of Ruditapes decussatus collected in the summer of 2017, from three locations at Alexandrian coasts, Egypt, Abo Quir, (loc.#1), Sedi Beshr (loc.#2) and (loc.#3), El-Max)  and to find out whether pollution alters the clam physiological functions or not. The present data showed that the highest mean value of salinity was reported in water samples collected from Abo Quir (loc.#1) and the highest level of dissolved oxygen was reported in water samples collected from Sedi Beshr (loc.#2). The present results showed that the studied heavy metals concentrations are highly significant in samples of water and soft tissue of Ruditapes decussatus collocated from Abo Quir bay. From the above cited results it is concluded that loc.#1(Abo Quir bay) represent the most polluted site in the present study. Statistical analysis showed significant increase of MDA and significant decrease of SOD and GPx in the soft tissue of Ruditapes decussatus collected from Abo-Quir Bay (loc.#1). There was high significant difference between tissue of clams collected from the three locations (p<0.001). The correlation coefficient of  physicochemical parameters, heavy metals in tissue, heavy metals in water  and oxidative stress biomarkers in Abo Quir Bay  (loc.#1) showed that; MDA mean activity concentration is positively correlated   with the mean activity level of  SOD at r = 0.844,  p = 0.035. The correlation coefficient between the five investigated heavy metals  Mn, Cu, Zn, Pb & Cd and oxidative stress bio-makers for the clam showed that in Abo Quir Bay (loc.#1), GPx is negatively correlated with Zn in tissue at r = -0.846 and p=0.034. On the other hand the Pb in tissue is positively correlated with mean Zn concentration in tissue at r = 0.878, p = 0.022.

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