Present address: National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Blvd East, Seattle, WA 98112, USA.
1365-2435/asset/olbannerleft.gif?v=1&s=c8b848a8f001fdfa90240fe2ab26b1f04b6fe8e4)
1365-2435/asset/olbannerright.gif?v=1&s=2cf6e00d281371851f86902da3937ac5884bcfe0)
You have full text access to this OnlineOpen article
Energy reserve allocation in fasting Northern Elephant Seal Pups: inter-relationships between body condition and fasting duration
Article first published online: 2 APR 2004
DOI: 10.1111/j.0269-8463.2004.00840.x
Additional Information
How to Cite
Noren, D. P. and Mangel, M. (2004), Energy reserve allocation in fasting Northern Elephant Seal Pups: inter-relationships between body condition and fasting duration. Functional Ecology, 18: 233–242. doi: 10.1111/j.0269-8463.2004.00840.x
Publication History
- Issue published online: 2 APR 2004
- Article first published online: 2 APR 2004
- Received 2 June 2003; revised 5 October 2003; accepted 17 October 2003
- Abstract
- Article
- References
- Cited By
Keywords:
- Dynamic state variable model;
- fasting metabolism;
- individual variation;
- lipid catabolism;
- protein catabolism
Summary
- 1Organisms are forced to make trade-offs when allocating energy reserves during sustained periods of fasting.
- 2For most animals, lipid catabolism is the preferred source of energy to safeguard important protein sources. However, marine mammals also have a compounding pressure to conserve some lipid stores. The main site of lipid storage in these animals is the blubber layer, which is not only an important energy source during fasting, but is also the primary thermal barrier when at sea.
- 3To explain how the allocation of protein and lipid reserves during fasting are influenced by body condition (body mass and percentage lipid of total body mass), a dynamic state variable model that takes into account fitness consequences of different allocation strategies was developed.
- 4This model was parameterized with respect to conditions faced by weaned Northern Elephant Seal (Mirounga angustirostris Gill) pups. It incorporates the independent effects of body mass and protein mass (the two state variables) on survival and the costs of utilizing either lipid or protein during the postweaning fast.
- 5Predictions of lipid and protein allocation by the model were not significantly different from measurements on wild seals. Finally, the model showed that body lipid content and fasting duration both influence allocation of energy reserves.