Diving Physiology and Behavior of Emperor Penguins

皇帝企鹅是南极生态系统中首屈一指的鸟类潜水员和顶级捕食者。500米潜水员出海觅食的例行公事既是一个生理之谜，也是一个行为之谜。这个项目的目标是解决皇帝们如何以及为什么潜水如此之深和如此之久。该项目考察了帝企鹅潜水生物学中的四个主要主题：压力耐受性、氧气储备管理、潜水低氧/缺血的终末器官耐受性以及深潜觅食行为。这些课题与皇帝在南极生态系统中作为顶级捕食者的角色有关，也与潜水生理学中的关键概念有关，包括减压病、氮气麻醉、浅水停电、耐低氧和延长有氧潜水时间。将检验以下假设：1)帝王企鹅的氮气麻醉和减压病的预防是通过抑制肺深部气体交换实现的。2)浅水停电不是因为大脑对低氧的耐受性较高，而在深潜时，是因为在最后一次上升时恢复了肺气体交换。3)血氧储备的耗尽率是潜水深度和心率的函数。4)有氧跳水极限(ADL)反映的是运动肌肉乳酸积累的开始，而不是所有储氧量的完全耗尽。5)组织抗氧化能力和自由基清除酶活性的提高对潜水过程中常规的缺血/再灌流具有保护作用。6)在深潜过程中，南极银鱼是帝王的主要猎物。除了对以下假设进行评估外，该项目还在几个领域产生了更广泛的影响，如与外国和国家研究所和组织(例如，日本国家极地研究所、墨西哥诺罗埃斯特调查中心、国家地理、德克萨斯大学西南医学中心和海洋世界)的伙伴关系。参与国家地理电视纪录片将为公众提供独特的教育机会；最先进技术的发展(如血氧电极记录仪、血液采样器和微型数码相机)将为该小组和其他人未来的研究奠定基础；B15冰山对帝企鹅繁殖成功的影响将继续通过在几个罗斯海帝企鹅群计划进行的实地考察期间进行的人口普查来评估。

The emperor penguin, Aptenodytes forsteri, is the premier avian diver and a top predator in the Antarctic ecosystem. The routine occurrence of 500-m diver during foraging trips to sea is both a physiological and behavior enigma. The objectives of this project address how and why emperors dive as deep and long as they do. The project examines four major topics in the diving biology of emperor penguins: pressure tolerance, oxygen store management, end-organ tolerance of diving hypoxemia/ischemia, and deep-dive foraging behavior. These subjects are relevant to the role of the emperor as a top predator in the Antarctic ecosystem, and to critical concepts in diving physiology, including decompression sickness, nitrogen narcosis, shallow water blackout, hypoxemic tolerance, and extension of aerobic dive time. The following hypotheses will be tested: 1) Prevention of nitrogen narcosis and decompression sickness in emperor penguins is achieved by inhibition of pulmonary gas exchange at depth. 2) Shallow water black out does not occur because of greater cerebral hypoxemic tolerance, and, in deep dives, because of resumption of pulmonary gas exchange during final ascent. 3) The rate of depletion of the blood oxygen store is a function of depth of dive and heart rate. 4) The aerobic dive limit (ADL) reflects the onset of lactate accumulation in locomotory muscle, not total depletion of all oxygen stores. 5) Elevation of tissue antioxidant capacity and free-radical scavenging enzyme activities protect against the routine ischemia/reperfusion which occur during diving. 6) During deep dives, the Antarctic silverfish, Pleuorogramma antarcticum, is the primary prey item for emperors. In addition to evaluation of the hypotheses below, the project has broader impacts in several areas such as partnership with foreign and national institutes and organizations (e.g., the National Institute of Polar Research of Japan, Centro de Investigacioines del Noroeste of Mexico, National Geographic, the University of Texas Southwestern Medical Center, and Sea World). Participation in National Geographic television documentaries will provide unique educational opportunities for the general public; development of state-of-the-art technology (e.g., blood oxygen electrode recorders, blood samplers, and miniaturized digital cameras) will lay the groundwork for future research by this group and others; and the effects of the B15 iceberg on breeding success of emperor penguins will continue to be evaluated with population censuses during planned fieldwork at several Ross Sea emperor penguin colonies.