SEASONAL AND LOCAL VARIATIONS OF METAL CONCENTRATIONS IN THE SEAGRASSPOSIDONIA-OCEANICA (L) DELILE IN THE ANTIKYRA GULF, GREECE

The accumulation of Fe, Pb, Zn, Cu, Cd, Na, K, Ca and Mg in the leaves of seagrass Posidonia oceanica (L.) Delile was studied in the Gulf of Antikyra. The investigated area was of interest because of the specif ic composition of its substrate (involving bauxite) and also because o f the nearby discharge wastes from an aluminium factory. All metal con centrations in the phanerogam were evenly distributed at the seven sta tions where there were adequate data for analysis. Cd, K and Ca displa yed significant seasonal variation with high concentrations in P. ocea nica during summer and autumn and low levels in winter and spring. Thi s variation could have been the effect of age-dependent distribution o f these metals in the leaves. Significant variation was also evident i n Pb concentrations, which was probably associated with the growth dyn amics of Posidonia oceanica. Other factors playing a role were the bio mass of calcareous epiphytes on the plant leaves (as concerns Ca) and the interactions of metals for binding by the plant tissues. The depen dence of metal concentrations in the plant on their concentrations in the environment (sediment and seawater) was also relevant. A significa nt correlation was found between Cd concentrations in the plant and th ose in sediment. A comparison between metal concentrations in P. ocean ica of the Antikyra Gulf and those of the species belonging to the sub family Posidonioideae from other areas is also presented. Cu, Pb, Cd, Fe, Ca and Mg concentrations in P. oceanica in the study area were gen erally high.