Expression of common biomarkers in Antarctic krill (Euphausia superba) exposed to an organochlorine contaminant

Abstract

Persistent organic pollutant (POP) contamination of Polar Regions continues to present a major ecological challenge and an environmental stressor to local biota. Antarctic krill (Euphausia superba) are a keystone species of the Antarctic sea ice ecosystem. Krill have repeatedly been found to accumulate a diverse array of POPs and thereby serve as vectors of these to the remainder of the Antarctic food web. p,p′-Dichlorodiphenyldichloroethylene (p,p′-DDE) is a dominant POP compound accumulating in Antarctic krill and higher trophic level predators. Recently, p,p′-DDE uptake dynamics, associated behavioural and developmental toxicity were evaluated in this species. The present study investigated the response of enzymes with known roles in detoxification (glutathione S-transferase, GST and cytochrome P450 2B, CYP2B), neurotoxicity (acetylcholinesterase, AChE) and oxidative stress (glutathione peroxidase GPx) in Antarctic krill exposed to p,p′-DDE. CYP2B was not detectable in Antarctic krill. No strong concentration responses resulted from the exposure to p,p′-DDE. These findings do not provide evidence for an activated detoxification response to this compound via the tested biochemical pathways in Antarctic krill. This is the first time that GST, AChE and GPx have been characterised in this species following pollutant exposure. Further research with additional pollutants and compound mixtures is necessary to assess the practical role of these enzymes as biomarkers of pollutant exposure in Antarctic krill. These first exploratory findings present a valuable contribution to a critical knowledge gap in polar ecotoxicology, namely the comparative sensitivity of polar organisms relative to temperate and tropical counterparts.