Influence of glacial runoff on baseline metal accumulation in the Antarctic limpet Nacella concinna from King George Island

Abstract

Abstract: Natural variability of baseline metal levels was investigated for the Antarctic limpet Nacella concinna with reference to massive land runoff (glacial-melt water inflow) during the summer months. Spatial variations in metal concentrations were investigated for the Antarctic limpet Nacella concinna on King George Island. A distinct temperature gradient was developed in the bay with lower temperatures near submerged glaciers and ice-melt water streams. Al concentrations were notably elevated in seawater at the sites where the surface water temperature was lower, indicating massive input of lithogenic particles along the melt water. Fe, Mn, Cu, Pb and Cr concentrations showed distributional patterns very similar to that of Al, and these concentrations were correlated highly with the concentrations of Al., clearly showing that the metals were associated with lithogenic particles introduced into the bay along with the glacier melt-water. Limpets were collected from several intertidal sites of varying degree of ice-melt water influence. In the limpet tissue Fe, Mn, Cu, Pb and other metals of the lithogenic sources are also found to be highly elevated at the sites close to the sources of the glacial melt-water input, showing that these elevations are natural. Thus metal levels in the limpet, Nacella concinna closely reflect gradients in physical environment, demonstrating the excellent 'indicator' properties of N. concinna. In particular, levels of Mn and Cu concentrations in the tissues of N. concinna near the melt-water sources were comparable to the values found in other patellid limpets from polluted waters. The results of this study suggest that spatial (probably temporal) variations in metal accumulation associated with melt-water inflow should be taken into account in elucidating baseline metal concentration of Antarctic marine biomonitor species.