Accumulation of Cu(II) and Pb(II) in Three Rhodophytes of the Genus Gracilaria and the Impact of the Metals on the Algal Physiology

Abstract

The accumulation of two heavy metals, copper (Cu(II)) and lead (Pb(II)) in the tissues of three Gracilaria species (Rhodophyta): G. edulis, G. manilaensis and G. salicornia and the impacts of the metals on the algal maximal quantum yield (i.e. Fv/Fm), relative growth and chlorophyll (chl) a content were studied. The algae were exposed to 1 mg L-1 of the metals individually for 8 hrs. Results showed that the three species of Gracilaria reacted differently against the two metals. For every kilogram of thallus, > 1000 mg of Cu(II) and Pb(II) was collected for G. edulis and G. manilaensis. Furthermore, both algae has a Bioconcentration Factor (BCF) value of >1 for both metals. G. salicornia, however, collected < 1000 mg Cu(II) and Pb(II) for every kilogram of thallus, and has a BCF value of >1 for Cu(II) and < 1 for Pb(II). These values indicate that all algae are good accumulators of Cu(II) while G. edulis and G. manilaensis are good accumulators of Pb(II) but G. salicornia, on the other hand, is an excluder of Pb(II). There was a reduction of the algal Fv/Fm in both metals, with the highest reduction observed for G. manilaensis in Cu(II). Relative growth of the algae was also reduced in both metals. Cu(II) induced the synthesis of chl a in G. edulis and G. salicornia but inhibited chl a synthesis in G. manilaensis while Pb(II) induced the production of chl a in all algae