HEAVY-METALS IN POSIDONIA-OCEANICA AND PARACENTROTUS-LIVIDUS FROM SEAGRASS BEDS OF THE NORTH-WESTERN MEDITERRANEAN

The concentrations of Zn, Pb, Cd, Fe, Cr, Cu and Ti were measured in s pecimens of the seagrass Posidonia oceanica and the echinoid Paracentr otus lividus from three meadows in the N.W. Mediterranean (Marseille, France; Ischia, Italy; Calvi, Corsica). The concentrations of Hg were measured in the same echinoid specimens. Investigated metals are selec tively distributed in the compartments of both species (i.e. the leaf- epiphyte complex, rhizome and root; and the digestive wall, gonads and body wall). Concentrations of most metals significantly differ in bot h the seagrass and the echinoid according to the considered meadow. Th ese differences are of low amplitude except for Fe, Ti, Cu and Hg. Con taminations by these four metals show significant departures from back ground concentrations in Ischia biotas. Contamination by Pb differs fr om the background levels in both species in the three sampled sites.