Effects of Foraging on the Lipid Biochemistry of Freely Diving Weddell Seals

点击翻译按钮获取中文摘要

The primary goal of this program is to quantify the dynamics of lipid uptake and utilization in a naturally foraging mammalian carnivore by examining freely diving Weddell seals in Antarctica. This species offers a unique opportunity to follow the biochemistry and physiology of nutrient utilization in a large carnivore that may not be possible in any other system. This is due to the essentially impossible logistics of working with large predators such as free-ranging felids (e.g, lions, tigers) or ursids (bears) and obtaining multiple blood samples and measuring digestive chemistry while the animal is actively foraging. While such studies can be conducted in laboratory or zoo settings, they are necessarily limited to using captive animals where feeding times are typically constrained by husbandry requirements and to human-determined diets. However, a unique opportunity to perform digestive chemistry experiments in actively foraging large carnivores in the wild exists in the Antarctic. For several decades, the Weddell seal has been the focus of studies on natural diving physiology because of the ability to work with the species using isolated holes in the sea ice near McMurdo Station, Antarctica. In that system, the seal has access to a single ice hole where it routinely returns to breathe, sleep, digest, etc. With the use of blood-sampling catheters, serial samples of blood can be collected whenever the seal returns to the surface between diving bouts. Seals rely primarily on lipid metabolism for their daily energy demands and in this new program, nutrient metabolism in predatory carnivores will be studied by examining the kinetics of lipid uptake and utilization during active foraging bouts. Labeled blood samples from freely diving animals will be used to quantify lipid turnover rates and to characterize the various components of the lipid pool. Adult seal lipid uptake and utilization will be compared to similar processes in pups, which are biochemically adapted for massive and rapid lipid utilization while nursing. This project will provide rare and perhaps unparalleled data on the foraging biochemistry of freely living carnivores. Results will also provide insight not only to Antarctic ecosystem studies, but to the entire field of lipid metabolism in mammals and to the study of carnivore biology.