Collaborative Research: Establishing baselines for nearshore marine ecosystems by examining sea otter trophic variation over 5,000 years of climatic and anthropogenic change

知识价值：pi将利用碳、氮和氧的天然稳定同位素来确定海獭的营养地位，以及它在阿拉斯加科迪亚克和阿留申东部地区从史前（5000年前）到历史（过去300年）时期的变化。将分析每个地区已知猎物物种的稳定同位素数据，构建同位素食物网，以比较海獭骨同位素比率随时间的变化。史前数据将来自垃圾堆中的动物遗骸。来自考古和现代贝壳的氧和碳稳定同位素数据以及来自海洋沉积物岩心的古代用数据将用于评估可能影响近岸生态系统的环境变化。这些数据将用于评估海獭营养地位和丰度最近急剧变化的机制解释。将被研究的现存种群中，有一种正在减少，而另一种则表现良好。理解这些不同的现代轨迹背后的机制是基本的生态和管理利益。更广泛的影响：本项目更广泛的影响建立在跨学科的研究、保护和管理上。这将是首次对跨越数千年的关键物种的同位素记录进行单系统、多地理的比较。这项研究将促进两所大学、一个博物馆和当地学校之间的跨学科研究、合作和教育。该项目包括与当地博物馆合作设计的外展计划，为青少年提供教育，参与正在进行的成人系列讲座，并为博物馆图书馆提供项目信息和结果，当地人和游客都可以访问。最后，本研究结果将有利于海獭、近岸海洋生态系统和渔业的长期保护和管理。

Intellectual Merit: The PIs will utilize natural stable isotopes of carbon, nitrogen and oxygen to define the trophic position of sea otters and how it has varied from pre-historic (5000BP) to historic (last 300 years) times in the Kodiak and eastern Aleutian regions of Alaska. Stable isotope data from known prey species in each area will be analyzed to construct an isotopic food web to compare with changes in sea otter bone isotope ratios over time. Prehistoric data will come from faunal remains in middens. Oxygen and carbon stable isotope data from archaeological and modern shells and paleo-proxy data from marine sediment cores will be used to evaluate changes in environment that may have affected nearshore ecosystems. These data will be used to evaluate mechanistic explanations for the dramatic recent changes in sea otter trophic position and abundance. One of the extant populations that will be studied is declining, while the other is doing well. Understanding the mechanisms behind these divergent modern trajectories is of fundamental ecological as well as management interest.Broader Impacts: The broader impacts of this project are founded in interdisciplinary research, conservation and management. This will be the first single-system, multiple-geographic, comparison of isotopic records of a keystone species that spans thousands of years. This study will promote interdisciplinary research, collaboration, and education across two universities, a museum, and local schools. Included in this project is an outreach program devised in conjunction with the local museum to provide youth education, participation in an ongoing lecture series for adults, and information on the project and results for the museum's library, which is accessed by bothlocals and visitors. Lastly, results of this study will benefit the long-term conservation and management of sea otters, nearshore marine ecosystems, and fisheries.