Investigation of heavy metal (Pb+) effect in presence of (Ca2+) on photosynthetic pigmentsand antioxidant enzymes activityof Entromorpha sp.

Lead as one of the most expanded metals in environment, effects on human health. Besides, the biological absorption by algae leads to the reduction of heavy metal pollutions in aqueoussolutions. In this study, accumulation and bioabsorption of Pb+ on biochemical characteristics of green alga Entromorpha was investigated. For this purpose, effects of  different concentrations of Pb2+ (0, 50, 100 and 150 µM Pb(SO4)2) in presence of two concentrations of Ca2+ (0 and 0.5 mM CaCl2) was studied in Entromorpha collected on Caspian Sea in two times of 3 and 8 days in random complete design with 4 replications for photosynthetic pigments content, membrane lipid peroxidation and antioxidant enzymes activity. The results indicated a decreasing rate of chlorophylla and b, total chlorophyll and carotenoid and also activity of polyphenoloxidase enzymewith increase of Pb2+ concentration and stress during. In membrane lipid peroxidation assay, malondialdehyde increased significantly by increase of Pb2+concentration. For these traits including chlorophyll, and carotenoid content and also membrane lipid peroxidation assay, effects of Pb2+ stress decreased by using CaCl2 treatment. The results of antioxidant assay showed that catalase, ascorbate peroxidase and peroxidase activities in both 3 and 8 days stress was high without CaCl2 treatment than using it. In general, the results of this study showed that Pb2+causes oxidative stress and biochemical changes in Enteromorpha green algae. Also, the presence of CaCl2 treatment reduces the effects of stress.