Evidence of Weak Contaminant-Related Oxidative Stress in Glaucous Gulls (Larus hyperboreus) from the Canadian Arctic

Abstract

Environmental contaminants are transported over great distances to Arctic ecosystems, where they can accumulate in wildlife. Whether contaminant concentrations in wildlife are sufficient to produce adverse effects remains poorly understood. Exposure to contaminants elevates oxidative stress with possible fitness consequences. The glaucous gull (Larus hyperboreus), an Arctic top predator, was used as a bioindicator for investigating relationships between contaminant levels (organochlorines and polychlorinated biphenyls [OC/PCB], mercury [Hg], and selenium [Se]) and measures of oxidative stress (glutathione [GSH] metabolism and lipid peroxidation) in Canadian Arctic ecosystems. Contaminant levels were low and associations between contaminant exposure and oxidative stress were weak. Nevertheless, glutathione peroxidase activity rose with increasing hepatic Se concentrations, levels of thiols declined as Hg and OC/PCB levels rose, and at one of the two study sites levels of lipid peroxidation were elevated with increasing levels of hepatic Hg. These results suggest the possibility of a deleterious effect of exposure to contaminants on gull physiology even at low contaminant exposures.

Funding was provided by Environment Canada's Northern Ecosystem Initiative, Natural Resources Canada's Polar Continental Shelf Program and the Department of Indian Affairs, and Northern Development's Northern Contaminants Program. Animals were collected in accordance with terms of scientific permits issued by Environment Canada and the Government of Nunavut, following protocols that were approved by the Canadian Wildlife Service Animal Care Committee acting on behalf of the Canadian Council of Animal Care. We thank M.-L. Gentes, J. M. Devink, I. Storm, E. Cumming, N. North, A. Idrissi, P. Dunlop, E. Neugebauer, S. VanWilgenberg, S. Lawson, J. Conkin, P. Scully, and R. Zega for their assistance.