Bioaccumulation of metals by the green alga Ulva rigida from Thermaikos Gulf, Greece

Fe, Pb, Cu, Zn and Cd concentrations in the green alga Ulva rigida C. Agardh and in the sediment and seawater were studied at five stations of the Thermaikos Gulf, which is the recipient of domestic and industrial wastes. The relative abundance of metals in U. rigida and seawater (concerning Zn, Pb, Cu, Cd) decreased in the order: Fe > Zn > Pb > Cu > Cd, whereas in the sediment the order was the same except in the case of Pb > Fe > Zn. The seasonal variation of metal concentrations in the alga was significant for Cd and Zn. The mean values in the alga increased from spring to fall reaching a maximum in October or June (only for Cu). These variations are discussed in relation to growth dynamics, the concentrations of metals in the environment and tissue age. The concentrations of all metals in the alga were distributed uniformly among the five stations. There is a significant positive correlation in U. rigida between Pb-Cu, Fe-Cu and Cd-Pb. Pb and Cu concentrations in the alga were positively correlated with the respective concentrations in the sediment. Pb, Zn and Cd values in U. rigida from the study area exceeded those in the same or other species of the genus from other areas. U. rigida could be regarded as an indicator species for Pb, Zn and Cd. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.