In vitro lead accumulation in Gracilaria coronopifolia and Gracilaria eucheumoides

Abstract

The effects of lead at different concentrations (0.02, 0.10, 1.0 and 5.0 ppm) on growth rate, total chlorophyll content, and dissolved oxygen production of Gracilaria coronopifolia and Gracilaria eucheumoides were investigated under laboratory conditions. The amount of lead accumulated in the plant tissue and in the agar extracted from the two Gracilaria species was determined by using the Spectra AAS atomic absorption spectrometer. Results showed that the specific growth rate in biomass of the two Gracilaria species did not differ significantly (P<0.05) among treatments. Although the chlorophyll content in G. coronopifolia decreased and G. eucheumoides increased at the end of the culture period, both species did not differ significantly among treatments. Dissolved oxygen production in all treatments decreased on the 15 th day of culture of both species. The amount of lead detected in the agar extracted from G. coronopifolia and G. eucheumoides was 2.1 to 31.4 times higher than the lead content in the tissues of both species. The amount of lead in the water medium significantly decreased after 15 days of culture. An important characteristic of G. coronopifolia and G. eucheumoides is their ability to absorb lead from water and survive in lead -contaminated waters with concentrations as high as 5ppm. These characteristics make both Gracilaria species good candidates for bioremediation as a means of improving water quality in nearshore ecosystems.