Effects on Growth and Accumulation of Zinc in Six Seaweed Species

Seaweed species from a coastal area contaminated by heavy metals (Sepetiba Bay) 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,andSpyridia filamentosa,were cultivated under laboratory semistatic conditions in five Zn concentrations in seawater, 10, 20, 100, 1000, and 5000 μg · liter−1for a period of 21 days. All species died at 5000 μg · liter−1of Zn, two species (U. lactucaandE. flexuosa) died at 1000 μg · liter−1, and one,H. musciformis,died with 100 μg · liter−1. The lowest concentration of Zn that presented growth inhibition in the six species was 20 μg · liter−1. The brown algaP. gymnosporapresented the highest accumulation level of Zn, andH. musciformisthe lowest level. The results of tolerance and accumulation under laboratory conditions, associated with field results, indicate the species ofPadinaandSargassumas the best species for monitoring heavy metals in tropical coastal areas, and the potential use of their biomass to remove heavy metals from wastewaters.