Abstract

In Chile, there are no references on the effects of mining discharges on populations and communities of the shallow subtidal habitats. During 1996-1997, covering more than 1500 km of coast (in polluted and control areas), a study was carried out to account for the chemical characterization of copper and iron discharges, the distribution of heavy metals in Lessonia trabeculata, the distribution of heavy metals in water, changes on Lessonia composition and quality of phycocolloid and morphology, as well as the effects upon the macroinvertebrate community associated with Lessonia holdfast and on the rocky subtidal community. The obtained data indicate that the levels of heavy metals in seawater, plants and alginates of Lessonia in contaminated and pristine sites are highly variable.Between June 1996 and August 1997, rocky subtidal environments affected by solid and liquid mine tailings from copper and iron mining in Chile were sampled, and heavy-metal concentrations were determined in seawater, in alginates, and in plants of Lessonia trabeculata. Population- and community-level effects were also considered. The results showed that Cu mining had caused more ecological perturbations than Fe mining. Perturbations were restricted to the 0-30 m depth, however, and up to 3 km from the contamination source. Although the concentrations of Cu and Fe in seawater exceeded background, they did not appear to generate modifications per se, as there were subtidal communities dominated by macroalgae in areas with high Cu and Fe concentrations in seawater. The concentrations of Cu and Fe in fronds, stipes, and holdfasts of L. trabeculata and in alginates showed no clear pattern as a function of the cation content in seawater. The community of macroinvertebrates associated with L. trabeculata exhibited a strong and significant reduction in species richness, density, and biomass of the intra-holdfast organisms in areas closer to the contamination. Communities on hard bottoms also showed similar responses.