Physiological constraints in marine mammals

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The response of animals to alterations in their environment is outwardly manifest as changes in their behaviour. Physiology represents the proximate controls as well as the capacity or limitations of the response. Bioenergetics is a measure of the sum result or consequences of these interactions in a currency (energy) that ultimately impacts health and survival. My research program investigates how physiology constrains the response of marine mammals to changes in their biotic or physical environment, and the resulting behavioural and energetic consequences. I specialize in marine mammals, given the unique demands placed upon them by their environment. One of the most striking aspects is the fact that they forage at depth but must return to the surface to breathe. This represents an extreme situation where the resultant behaviour embodies a compromise between competing long-term (energy balance) and short-term (oxygen balance) physiological demands. This dichotomy has spawned an entire subfield of optimal foraging models based on underlying physiological capacity and energetic costs. Thermoregulatory capacity is also an important physiological consideration in this group of animals, given the high conductivity of their environment and the conflicting demands on their blubber layer as both an insulative organ and an energy reserve. Additionally, there are innate physiological conflicts between diving abilities, digestion, and thermoregulatory abilities that must be resolved in light of nutritional states and hormone-mediated seasonal energetic priorities. Understanding physiological limitations and energetic consequences of behavioural responses has become more critical given recent rapid environmental changes that may impact prey distribution and substrate stability of many marine mammals. ******I have proposed three specific avenues of research inquiry to be undertaken in the immediate future. The program will investigate (i) the physiological control of dive behaviour in marine mammals, (ii) seasonal interactions between diving physiology, energy budgets, and nutrition, and (iii) the effects of changes in environmental conditions on pinniped energy budgets and physiology. Together, these studies will contribute to our understanding of the energetic consequences, physiological controls, and behavioural responses of marine mammals to changes in their environment.