Oxidative damage and antioxidant defence parameters in the Antarctic bivalve Laternula elliptica as biomarkers for pollution impacts

The Antarctic continent is increasingly vulnerable to anthropogenic pollution; however, assessments of the impacts that chemical pollutants have on cold-adapted marine organisms are limited. Oxidative stress (OS) occurs when the rate of reactive oxygen species generation exceeds the scavenging capacity of an organism's antioxidant (AO) system and is an important unifying feature underlying the toxicity of many chemical contaminants in aquatic organisms. The Antarctic bivalve Laternula elliptica is a widely distributed, infaunal filter-feeding organism. We analysed AO enzyme activities, levels of the molecular antioxidant glutathione, protein carbonylation and lipid peroxidation as OS biomarkers in L. elliptica from contaminant-impacted sites near McMurdo Station and the relatively pristine Cape Evans. The objective was to evaluate the effectiveness of these biomarkers for detecting contaminant stress in this cold-adapted marine invertebrate. The concentrations of total polycyclic aromatic hydrocarbons were quantified as a proxy for contamination and found to be elevated in gonad and muscle tissues from L. elliptica dwelling in contaminated sites. These individuals exhibited a greater degree of OS than those from the reference site, evidenced by increases in oxidative lipid and protein damage, as well as an upregulation of AO defences. Coincidentally, L. elliptica from the contaminated sites were significantly smaller in shell length (1.3-fold) than those from the reference site. Oxidative biomarkers proved to be useful indicators of contamination exposure in the present study and were used to document ongoing biological impacts from historic and current pollution in McMurdo Sound.