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

智力价值：PI将利用碳、氮和氧的天然稳定同位素来定义海獭的营养位置，以及它如何在阿拉斯加的科迪亚克和阿留申东部地区从史前(5000 BP)到历史(过去300年)的变化。将对每个地区已知猎物物种的稳定同位素数据进行分析，以构建一个同位素食物网，与海獭骨骼同位素比率随时间的变化进行比较。史前数据将来自中部的动物遗骸。将利用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替代数据来评估可能已影响近岸生态系统的环境变化。这些数据将被用来评估对最近海獭营养位置和丰度发生戏剧性变化的机械解释。将被研究的现存种群中，有一个正在减少，而另一个则表现良好。了解这些不同的现代轨迹背后的机制具有基本的生态和管理利益。更广泛的影响：该项目的更广泛影响建立在跨学科的研究、保护和管理中。这将是第一次对跨越数千年的关键物种的单系统、多地域的同位素记录进行比较。这项研究将促进两所大学、一家博物馆和当地学校的跨学科研究、合作和教育。该项目包括与当地博物馆联合设计的一个外联计划，以提供青年教育，参加正在进行的成人系列讲座，并为博物馆的图书馆提供关于该项目和结果的信息，当地人和参观者都可以进入。最后，这项研究的结果将有利于海獭、近岸海洋生态系统和渔业的长期养护和管理。

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.