Collaborative Research: Investigating Holocene Shifts in the Diets and Paleohistory of Antarctic Krill Predators

南极海洋生态系统生产力很高，支持各种具有生态和商业重要性的物种。这一生态系统中的一个关键物种是南极磷虾，除了商业捕捞外，它还是包括企鹅、海豹和鲸鱼在内的各种海洋生物的主要猎物。这项研究的目的是利用企鹅和其他磷虾捕食者作为南极海洋食物网过去变化的敏感指标，这些变化是由于气候变化和人类对海豹和鲸鱼的历史性捕捞造成的。具体地说，这项研究将恢复和分析现代(20岁)、历史(20-200岁)和古代(200-10,000岁)企鹅和其他磷虾捕食者的组织，以跟踪它们过去的饮食和相对于气候变化和南极磷虾可获得性的种群迁移。了解磷虾捕食者在过去如何受到这些因素的影响，将使我们更好地了解这些捕食者、它们所依赖的磷虾以及整个南极海洋生态系统将如何应对当前的挑战，如全球气候变化和南极磷虾商业渔业的扩大。该项目将推动美国国家科学基金会培养新一代科学家和向公众提供科学发现的目标。该项目将支持本科生和研究生在生态学和生物地球化学领域的高级分析技术方面的跨机构培训。此外，该项目还包括旨在通过让K-12学生参与与南极洲、企鹅、海洋生态、生物地球化学和全球气候变化有关的科学问题的教育推广活动。这项研究将结合气候变化和商业收获，通过研究南极磷虾捕食者(企鹅、海豹和鱿鱼)的饮食和种群迁移的十年和千年尺度的变化，帮助将南大洋最近的生态变化置于更大的历史背景中。这将通过结合先进的稳定和放射性同位素技术，特别是化合物特定的稳定同位素分析，史无前例地获得整个全新世南极捕食者组织的现代、历史和保存完好的古档案来实现。这种方法将使该项目能够经验性地测试在过去数千年中观察到的南极捕食者整体组织稳定同位素值的变化是否是由于气候驱动的食物网底部的变化以及捕食者饮食的变化造成的，或者更确切地说，是由于历史性的捕食磷虾鲸鱼和海豹后竞争性释放造成的。此外，该项目还将跟踪南极洲周围企鹅群在过去几千年来因应气候和海冰条件的变化而被大规模抛弃和重新占领的情况。这些综合的实地研究和实验室分析将为影响企鹅等富有魅力的磷虾捕食者过去的饮食变化和种群迁移的潜在机制提供新的见解。这将有助于改进对未来气候变化的生态系统后果的预测，以及可能影响南极磷虾可获得性的南极人为捕捞情景。

The Antarctic marine ecosystem is highly productive and supports a diverse range of ecologically and commercially important species. A key species in this ecosystem is Antarctic krill, which in addition to being commercially harvested, is the principle prey of a wide range of marine organisms including penguins, seals and whales. The aim of this study is to use penguins and other krill predators as sensitive indicators of past changes in the Antarctic marine food web resulting from climate variability and the historic harvesting of seals and whales by humans. Specifically this study will recover and analyze modern (20 year old), historic (20-200 year old) and ancient (200-10,000 year old) penguin and other krill predator tissues to track their past diets and population movements relative to shifts in climate and the availability of Antarctic krill. Understanding how krill predators were affected by these factors in the past will allow us to better understand how these predators, the krill they depend on, and the Antarctic marine ecosystem as a whole will respond to current challenges such as global climate change and an expanding commercial fishery for Antarctic krill. The project will further the NSF goals of training new generations of scientists and of making scientific discoveries available to the general public. This project will support the cross-institutional training of undergraduate and graduate students in advanced analytical techniques in the fields of ecology and biogeochemistry. In addition, this project includes educational outreach aimed encouraging participation in science careers by engaging K-12 students in scientific issues related to Antarctica, penguins, marine ecology, biogeochemistry, and global climate change.This research will help place recent ecological changes in the Southern Ocean into a larger historical context by examining decadal and millennial-scale shifts in the diets and population movements of Antarctic krill predators (penguins, seals, and squid) in concert with climate variability and commercial harvesting. This will be achieved by coupling advanced stable and radio isotope techniques, particularly compound-specific stable isotope analysis, with unprecedented access to modern, historical, and well-preserved paleo-archives of Antarctic predator tissues dating throughout the Holocene. This approach will allow the project to empirically test if observed shifts in Antarctic predator bulk tissue stable isotope values over the past millennia were caused by climate-driven shifts at the base of the food web in addition to, or rather than, shifts in predator diets due to a competitive release following the historic harvesting of krill eating whale and seals. In addition, this project will track the large-scale abandonment and reoccupation of penguin colonies around Antarctica in response to changes in climate and sea ice conditions over the past several millennia. These integrated field studies and laboratory analyses will provide new insights into the underlying mechanisms that influenced past shifts in the diets and population movements of charismatic krill predators such as penguins. This will allow for improved projections of the ecosystem consequences of future climate change and anthropogenic harvesting scenarios in the Antarctica that are likely to affect the availability of Antarctic krill.