Is climate change poised to exacerbate contaminant-related health risks in marine mammals?

Peter Ross, chercheur à Pêches et Océans Canada, vient de présenter des résultats fort intéressants à la "18ième Conférence biennale sur la biologie des mammifères marins" qui s'est tenu du 12 au 16 octobre 2009, dans le centre de la capitale québécoise (Canada) et qui a réuni plus de 1500 scientifiques du monde entier. Ce congrès était organisé par la "Society for Marine Mammalogy".

Le résumé de la communication (retrouvez une version française et vulgarisée des travaux présentés par Peter Ross : ici) :

Increasing sea surface temperatures may lead to diminished ocean productivity in some areas of the world, raising the spectre of energetic stresses on certain marine mammal populations. Since persistent organic pollutants (POPs) are fat-soluble contaminants that amplify in marine mammal food webs, any productivity-related reduction in lipids will concentrate POPs in the diminishing blubber stores of marine mammals. We highlight here evidence from our research that illuminates our climate - contaminant hypothesis in marine mammals: 1) 'thinner' harbour seals have higher POP concentrations in lipid; 2) high polychlorinated biphenyl (PCB) concentrations in Puget Sound harbour seals can only be explained if they consume more fish to compensate for reduced lipid content observed in prey; 3) very high PCB concentrations in endangered southern resident killer whales in the NE Pacific Ocean relative to their northern resident counterparts also appear to be explained by a higher consumption of salmon to compensate for reduced prey lipid content; 4) PCB-associated  disruption of thyroid hormone receptor expression and circulating thyroid hormones in Puget Sound seals may be causing increased metabolic turnover as a consequence of PCB toxicity. Collectively, our contaminant-oriented research suggests that marine mammals consume more prey under two conditions: 1) when their prey contains lower lipid content, and 2) when PCBs disrupt thyroid physiology and alter metabolism. In the former case, climate change-associated impacts on the nutritional quality of prey may increase POP exposure through increased consumption. In the latter case, PCB-associated thyroid toxicity may be exacerbated by a climate-driven 'concentration effect' for toxic chemicals, and lead to increased POP exposure as a result of increased energetic needs. We speculate that these two scenarios will act synergistically in a warming ocean to increase POP exposure and associated health risks in some long-lived, high trophic level marine mammals.

Authors: Ross, Peter S.¹; Cullon, Donna^{2, 1}; Buckman, Andrea¹; Jeffries, Steve³; Helbing, Caren²; Ford, John K.B.⁴

(1) Fisheries and Oceans Canada, 9860 West Saanich Rd, Sidney, BC, V8L 4B2, Canada
(2) University of Victoria, P.O. Box 3055, Victoria, British Columbia, V8W 3P6, Canada
(3) Washington Department of Fish and Wildlife, 7801 Phillips Road, Tacoma, Washington, 98498, USA
(4) Fisheries and Oceans Canada, Hammond Bay Road, Nanaimo, British Columbia, V9R 5K6, Canada

Corresponding author: peter.s.ross@dfo-mpo.gc.ca
 

Comments

[Faculté des Sciences de la Terre, de la Géographie et de l'Aménagement du Territoire]

merci pour votre publication bonne continuation