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

南极海洋生态系统具有很高的生产力，支持着各种具有重要生态和商业价值的物种。南极磷虾是这个生态系统中的一个关键物种，除了用于商业捕捞外，它还是包括企鹅、海豹和鲸鱼在内的多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，这些变化是由气候变化和历史上人类捕杀海豹和鲸鱼造成的。具体来说，这项研究将恢复和分析现代（20年），历史（20-200年）和古代（200-10,000年）企鹅和其他磷虾捕食者的组织，以跟踪它们过去的饮食和人口流动与气候变化和南极磷虾的可用性有关。了解过去这些因素是如何影响磷虾捕食者的，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。该项目将进一步实现国家科学基金会培养新一代科学家和使科学发现向公众开放的目标。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先进分析技术的跨机构培训。此外，该项目还包括旨在鼓励K-12学生参与与南极洲、企鹅、海洋生态学、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。这项研究将通过研究南极磷虾捕食者（企鹅、海豹和鱿鱼）的饮食和人口流动与气候变化和商业捕捞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下。这将通过结合先进的稳定同位素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，以及前所未有的对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的访问来实现。这种方法将使该项目能够从经验上测试，在过去的几千年里，南极捕食者的总体组织稳定同位素值的变化是否由气候驱动的食物网底部的变化引起，或者更确切地说，由于磷虾捕食鲸鱼和海豹的历史性收获后的竞争性释放，捕食者的饮食发生了变化。此外，该项目还将追踪过去几千年来，由于气候和海冰条件的变化，南极洲周围的企鹅栖息地被大规模遗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魅力磷虾捕食者过去饮食变化和人口流动的潜在机制提供新的见解。这将有助于更好地预测未来气候变化和南极人为捕捞可能影响南极磷虾供应量的生态系统后果。

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.