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Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data.

Pavlova V, Nabe-Nielsen J, Dietz R, Svenning JC, Vorkamp K, Rigét FF, Sonne C, Letcher RJ, Grimm V - PLoS ONE (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Aarhus University, Department of Bioscience, Section for Marine Mammal Research, Roskilde, Denmark.

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.

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Tested combinations of deposition efficiencies and field metabolic factors.a) Only few combinations of proportionality constants: ωA ( = AA×fA) and ωY( = AY×fY) produced predictions not significantly different from actual data: in older bears (blue), yearlings (yellow) or both groups (green). All tested combinations are coloured grey. b) Combinations of ωA and ωY that produced predictions not significantly different from actual data in both studied groups exhibited a negative relationship.
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pone-0104037-g003: Tested combinations of deposition efficiencies and field metabolic factors.a) Only few combinations of proportionality constants: ωA ( = AA×fA) and ωY( = AY×fY) produced predictions not significantly different from actual data: in older bears (blue), yearlings (yellow) or both groups (green). All tested combinations are coloured grey. b) Combinations of ωA and ωY that produced predictions not significantly different from actual data in both studied groups exhibited a negative relationship.

Mentions: Visual representation of all values of proportionality constants ωA and ωY allowed us to gain a better insight into the influence of the combined age group specific parameters on the significance (or non – significance) of the results (Fig. 3a). The contamination levels in yearlings never prevented a realistic contamination time trend to arise for adult bears: with almost any value of ωY non-significantly different regression lines in both slope and intercept could be obtained for adults. On the other hand, for yearlings neither ωA nor ωY could be too high. This means that the contaminant levels in older bears determined the contaminant levels in yearlings to a large degree, but not vice versa. The reason is that the body burdens in yearlings formed only a small part of the total body burden of the older bears.


Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data.

Pavlova V, Nabe-Nielsen J, Dietz R, Svenning JC, Vorkamp K, Rigét FF, Sonne C, Letcher RJ, Grimm V - PLoS ONE (2014)

Tested combinations of deposition efficiencies and field metabolic factors.a) Only few combinations of proportionality constants: ωA ( = AA×fA) and ωY( = AY×fY) produced predictions not significantly different from actual data: in older bears (blue), yearlings (yellow) or both groups (green). All tested combinations are coloured grey. b) Combinations of ωA and ωY that produced predictions not significantly different from actual data in both studied groups exhibited a negative relationship.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4125222&req=5

pone-0104037-g003: Tested combinations of deposition efficiencies and field metabolic factors.a) Only few combinations of proportionality constants: ωA ( = AA×fA) and ωY( = AY×fY) produced predictions not significantly different from actual data: in older bears (blue), yearlings (yellow) or both groups (green). All tested combinations are coloured grey. b) Combinations of ωA and ωY that produced predictions not significantly different from actual data in both studied groups exhibited a negative relationship.
Mentions: Visual representation of all values of proportionality constants ωA and ωY allowed us to gain a better insight into the influence of the combined age group specific parameters on the significance (or non – significance) of the results (Fig. 3a). The contamination levels in yearlings never prevented a realistic contamination time trend to arise for adult bears: with almost any value of ωY non-significantly different regression lines in both slope and intercept could be obtained for adults. On the other hand, for yearlings neither ωA nor ωY could be too high. This means that the contaminant levels in older bears determined the contaminant levels in yearlings to a large degree, but not vice versa. The reason is that the body burdens in yearlings formed only a small part of the total body burden of the older bears.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Aarhus University, Department of Bioscience, Section for Marine Mammal Research, Roskilde, Denmark.

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.

Show MeSH