HEAVY-METAL ACCUMULATION BY FUCUS-CERANOIDES IN A SMALL ESTUARY IN NORTH-WEST SPAIN

Concentrations of Fe, Al, Mn, Cu, Ni, Co, and Zn were measured in Fucu s ceranoides and F. vesiculosus from Pontedeume, a small estuary on th e north-west coast of Spain, affected by mining activities upstream an d by sewage discharge to the estuary itself. Plants were collected fro m two intertidal levels at each of six locations, each sample eventual ly consisting of the homogenized tissues of ten individuals. Tips and thalli were analysed separately. By using these methods, it was found that three or four samples were sufficient to detect differences betwe en means for different sites of 50% for all the metals considered exce pt Cu, the high variability of which made eight samples necessary in o rder to detect differences of 100%. It was demonstrated that the contr ibution of particulate matter not removed during washing prior to anal ysis is significant only in the cases of Fe, Al and Cr. Mn and Co, and , to a less but still considerable extent, Ni and Zn, were found to be greatly enriched in the algae studied Concentrations in mature tissue s were higher than in apices for all the metals studied except Cu, for which there were no significant differences between the two tissues. The vertical position on shore did not affect apical metal concentrati ons but showed correlations with Mn, Co, Ni, Zn and Cu in mature tissu es. Possible reasons for these correlations are discussed.