Effects on growth and accumulation of zinc in six seaweed species

Seaweed species from a coastal area contaminated by heavy metals (Sepetiba Bag) in Rio de Janeiro State (Brazil) presented different levels of Zn concentrations, In some species the levels were 20 times higher than that from a noncontaminated area, The present study was undertaken to investigate the capability of different species to tolerate and accumulate zinc, For this purpose six species, Ulva lactuca, Enteromorpha flexuosa, Padina gymnospora, Sargassum filipendula, Hypnea musciformis, and Spyridia filamentosa, were cultivated under laboratory semistatic conditions in five Zn concentrations in seawater, 10, 20, 100, 1000, and 5000 mu g.liter(-1) for a period of 21 days, All species died at 5000 mu g.liter(-1) of Zn, two species (U. lactuca and E. flexuosa) died at 1000 mu g.liter(-1), and one, H. musciformis, died with 100 mu g.liter(-1). The lowest concentration of Zn that presented growth inhibition in the six species was 20 pg liter(-1). The brown alga P. gymnospora presented the highest accumulation level of Zn, and LI. musciformis the lowest level. The results of tolerance and accumulation under laboratory conditions, associated with field results, indicate the species of Padina and Sargassum as the best species for monitoring heavy metals in tropical coastal areas, and the potential use of their biomass to remove heavy metals from wastewaters. (C) 1997 Academic Press.