Does acute lead (Pb) contamination influence membrane fatty acid composition and freeze tolerance in intertidal blue mussels in arctic Greenland?

Abstract

In their natural habitats, organisms are exposed to multiple stressors. Heavy metal contamination stresses the cell membrane due to increased peroxidation of lipids. Likewise, sub-zero air temperatures potentially reduce membrane functionality in ectothermal animals. We tested if acute lead (Pb) exposure for 7 days would influence survival in intertidal blue mussels (Mytilus edulis) after exposure to realistic sub-zero air temperatures. A full factorial experiment with five tissue Pb concentrations between 0 and 3500 μg Pb/g and six sub-zero temperatures from 0 to -17 °C were used to test the hypothesis that sub-lethal effects of Pb may increase the lethality caused by freezing in blue mussels exposed to temperatures simulating Greenland winter conditions. We found a significant effect of temperature on mortality. However, the short-term exposure to Pb did not result in any effects of Pb, nor did we find interactions between Pb and temperature. We analysed the relative abundance of major phospholipid fatty acids (PLFAs) in the gill tissue, but we found no significant effect of Pb tissue concentration on PLFA composition. Results suggest that Pb accumulation has limited effects on freeze tolerance and does not induce membrane damage in terms of persistent lipid peroxidation.

Keywords: Arctic; Freeze tolerance; Indicator; Mining; PLFA; Risk assessment.