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

该计划的主要目标是通过检查南极自由潜水的威德尔海豹，量化自然觅食的哺乳动物食肉动物脂质摄取和利用的动态。这个物种提供了一个独特的机会来研究大型食肉动物营养利用的生化和生理学，这在任何其他系统中都是不可能的。这是由于与大型捕食者(如自由放养的猫科动物（如狮子、老虎）或熊科动物（熊）一起工作，以及在动物积极觅食时获取多种血液样本和测量消化化学物质，这些基本上是不可能的后勤工作。虽然这类研究可以在实验室或动物园环境中进行，但它们必然局限于圈养动物，因为圈养动物的喂养时间通常受到饲养要求和人为饮食的限制。然而，南极有一个独特的机会，可以在野外积极觅食的大型食肉动物身上进行消化化学实验。几十年来，威德尔海豹一直是自然潜水生理学研究的焦点，因为可以利用南极洲麦克默多站附近海冰上的孤立洞来研究威德尔海豹。在这个系统中，海豹可以进入一个冰洞，它通常会回到那里呼吸、睡觉、消化等。使用血液采样导管，每次海豹在潜水之间返回水面时，都可以收集到一系列的血液样本。海豹主要依靠脂质代谢来满足它们的日常能量需求，在这个新的项目中，掠食性食肉动物的营养代谢将通过检查活跃觅食过程中脂质摄取和利用的动力学来研究。来自自由潜水动物的标记血液样本将用于量化脂质周转率并表征脂质池的各种成分。成年海豹的脂质摄取和利用将与幼崽的类似过程进行比较，幼崽在哺乳过程中适应了大量和快速的脂质利用。这个项目将为自由生活的食肉动物的觅食生物化学提供罕见的，也许是无与伦比的数据。研究结果不仅将为南极生态系统研究提供新思路，而且将为整个哺乳动物脂质代谢领域和食肉动物生物学研究提供新思路。

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.