Evaluation of Cladophora laetevirens (Chlorophyta) and Patella caerulea (Mollusca) as bioindicators for heavy metals Pollution at Al-Hanyaa Mediterranean Coast, Libya.

Abstract

 This study was designed to evaluate the new record seaweed Cladophora laetevirens (Dillwyn) Kützing (Chlorophyta: Cladophorales) and Patella caerulea Linnaeus (Mollusca: Gastropoda) as bioaccumulating agents. The samples of two species were collected from polluted and unpolluted (reference) sites from the rocky shores of Al-Hanyaa coasts, Libya. Zinc (Zn), cadmium (Cd), lead (Pb) and copper (Cu) were determined using voltammetric technique. The results exhibited that, Cu occupied the highest level (559.15 ± 68.55 µg g^-1 fresh weights) among metals accumulated by Cl. laetevirens in polluted site, followed by Pb and vice versa in unpolluted site, where Pb attained 179.71 ± 31.19 µg g^-1 fresh weight. Despite that Cd has minimal concentration levels (either in Cl. laetevirens or P. caerulea tissues, at both sites), it recorded maximal bioaccumulation factors (BAFs) for Cl. laetevirens in both sites. Metal pollution index (MPI)  recorded in a descending order as: Cl. laetevirens > P. caerulea gut > P. caerulea muscle for both sites. Cadmium was positively correlated with Cu and Pb in both sites. The present data and their analysis proved the consistency, appropriateness, tolerance and reliability of Cl. laetevirens as a bioindicator regardless the metal concentration levels in seawater. These resultsconfirmedthat Cl. laetevirens is the strongest accumulator for Cu, Pb and Cd while P. caerulea is a potential accumulator for Zn.

 Keywords: Cladophora laetevirens; Patella caerulea; heavy metals;Al-Hanyaa; Libya; bioindicators