Meeting Abstract
54.7 Tuesday, Jan. 6 The Challenge of Energetic and Thermal Balance in Aquatic Environments: a simple bioenergetic-behavioral model for sea otters YEATES, Laura C.*; WILLIAMS, Terrie M.; TINKER, M. Tim; Univ. of California Santa Cruz; Univ. of California Santa Cruz; Univ. of California Santa Cruz yeates@biology.ucsc.edu
Because of its high surface to volume ratio, elevated metabolic demands, and reliance on fur insulation, the sea otter represents an extreme example of the energetic and thermal challenges of marine living by mammals. To assess daily activity patterns and budgets, twenty two adult sea otters (6 males,16 females) were captured and tagged using temperature sensitive VHF radio transmitters. Additionally, two captive adult sea otters were used to measure energetic costs of foraging, grooming, swimming and resting. Data from daily activity budgets, behavior specific energetic costs and the relationships between core body temperature and behavior were used to develop an integrated bio-energetic behavioral model for wild otters. The model was used to address the importance of maintaining an elevated core body temperature while living in water, how changes in the proportion of the day spent performing energetically costly behaviors affect energy stores, and how the caloric value of prey impacts the cost to benefit ratio. In simulation 1, thermal stability was dependent on the heat increment of associated with a predictable schedule of meals occurring throughout the day and night. Engaging in energetically costly behaviors such as swimming to different areas to obtain food quickly put the sea otter into an energy deficit, although body temperature could be maintained. In simulation 3, the availability of high quality food resulted in a surplus of energy and cost benefit ratio of 2.5 while poor quality or dispersed food resulted in cost benefit ratio of 0.7. Using a relatively simple bioenergetic-behavioral approach can provide insight into the vulnerability of this small, recently evolved marine mammal to such perturbations and may applicable to other mammals as well.
