Heavy metals in Posidonia oceanica and Paracentrotus lividus from seagrass beds of the north-western Mediterranean

The concentration of Zn, Pb, Cd, Fe, Cr, Cu and Ti were measured in specimens of the seagrass Posidonia oceanica and the echinoid Paracentrotus 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 selectively 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 both the seagrass and the echinoid according to the considered meadow. These differences are of low amplitude except for Fe, Ti, Cu and Hg. Contaminations by these four metals show significant departures from background concentrations in Ischia biotas. Contamination by Pb differs from the background levels in both species in the three sampled sites.