Field Metabolic Rate and PCB Adipose Tissue Deposition Efficiency in East Greenland Polar Bears Derived from Contaminant Monitoring Data

Abstract

Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2′,4,4′,55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.

Risk of POP mixtures on the Arctic food chain

“…However, the consequences of global changes have not been considered in the present study, and the main assumption is that polar bear feed only on ringed seal. A similar diet simplification was assumed recently by Pavlova et al in their modeling exercise.…”

Polyhalogenated compounds (PCBs, chlordanes, HCB and BFRs) in four polar bears (Ursus maritimus) that swam malnourished from East Greenland to Iceland

“…These scenarios indicate that the East Greenland population of polar bears may be more endangered than anticipated. A recent simulation of the field metabolic rate indicated that even relatively small reductions in feeding opportunities could affect the survival of the polar bears in East Greenland (Pavlova et al, 2014).…”

Toxicology of Marine Mammals: New Developments and Opportunities

“…Models in marine mammal toxicology follow the same principles, but face probably more challenges as the biology and physiology of most marine mammal species is often scarcely known and biomonitoring data is usually focussed on just a few tissues. Nevertheless, several types of marine mammal models are available for cetaceans and pinnipeds (reviewed in Weijs et al 2014) and polar bears (Sonne et al 2009;Pavlova et al 2014).…”