Heavy metal contents in soft-bottom marine macrophytes and sediments alongthe Mediterranean coast of Spain

Hg, Cd, Pb and Zn concentrations were determined in sediment and in tissues of five species of soft-bottom marine macrophytes (Posidonia oceanica, Cym odocea nodosa, Zostera noltii, Ruppia cirrhosa and Caulerpa prolifera) alon g the Spanish Mediterranean coast. Levels of metals were low in most of the sampling stations and similar to those found by other authors in uncontami nated zones. Certain locations, however, showed some degree of contaminatio n (Cambrils, Almassora, Alacant, Mar Menor and El Portus). In Santa Pola we found high contents of metals in one sample of sediment due to the high pr oportion of the fine fraction (particules < 63 mu m) and organic matter, bu t not in the seagrass species. Mercury and zinc concentrations in the sedim ent are correlated to those in at least some anatomic fractions of Posidoni a oceanica, Cymodocea nodosa and Caulerpa prolifera, suggesting that these species reflect the levels of these metals in the environment. Lead content s in the alga Caulerpa prolifera are also correlated to those in the sedime nt, while no significant correlations were obtained for cadmium. Among the species studied, Posidonia oceanica and Cymodocea nodosa seem to be better biomonitors than Caulerpa prolifera.