Predator-prey interactions in dynamic arctic ecosystems

气候变化正在从根本上改变北极生态系统。变暖的温度正在改变物种的分布，而海冰栖息地正在以在当前气候条件下不可逆转的方式发生变化。在陆地和海洋环境中，在食物网底部附近开始的生态变化可能很难检测到，特别是在早期阶段。然而，这样的变化可能会对顶级(顶端)捕食者的饮食产生显著影响。这项研究的长期目标是确定在多个时间和空间尺度上影响捕食者觅食的自然和人为因素。饮食数据将反映海洋和陆地环境中个体对种群规模的反应，并将具有重要的理论和应用意义；数据将揭示气候变化的生态影响，并指导制定适当的管理和养护战略。短期内，这项研究将为研究自由放养的捕食者的觅食习性提供改进和创新的方法。我将使用脂肪酸图谱和稳定同位素分析相结合的方法来研究北极熊(Ursus Maritimus)、灰熊(U.arctos)、狼(Canis Lupus)和狼獾(Gulo Guo)的摄食生态。这些技术基于对饮食成分的生化结合，其结果反映了几周到几个月的综合饮食构成。将这些技术与身体状况、繁殖和动物运动的数据相结合，将允许在4个核心领域进行创新：1)识别可用于研究捕食者饮食的新生物标记物；2)使用圈养和自由放养的动物检查大型食肉动物的营养生理学；3)检验栖息地条件和生态系统生产力影响顶级捕食者觅食行为的假设；以及4)通过猎物可获得性的变化来量化海冰变化与北极熊能量摄入量之间的关系。这些调查将支持培训许多高素质的人员，并为评估北极生态系统未来的变化提供一个量化的数据框架。

Climate change is fundamentally altering arctic ecosystems. Warming temperatures are changing the distribution of species while sea ice habitat is being transformed in ways that are irreversible under current climatic conditions. In terrestrial and marine environments, ecological shifts initiated near the base of the food web may be difficult to detect, especially in the early stages. However, such changes may have pronounced effects on the diets of top (apex) predators. The long-term objective of this research is to identify the natural and anthropogenic factors that influence predator foraging over multiple temporal and spatial scales. Dietary data will reflect individual- to population-scale responses in marine and terrestrial environments and will have important theoretical and applied implications; data will reveal the ecological impacts of climate change and guide the development of appropriate management and conservation strategies. In the short-term, this research will produce improved and innovative methods for studying the foraging habits of free-ranging predators. I will examine the feeding ecology of polar bears (Ursus maritimus), grizzly bears (U. arctos), wolves (Canis lupus), and wolverines (Gulo gulo) using a combination of fatty acid profiles and stable isotope analyses. These techniques are based on the biochemical incorporation of dietary components and their results reflect integrated diet composition over a span of weeks to months. Combining these techniques with data on body condition, reproduction, and animal movement will allow innovation in 4 core areas: 1) Identification of novel biomarkers that can be used to study predator diets; 2) Examination of the nutritional physiology of large carnivores using captive and free-ranging animals; 3) Testing the hypothesis that habitat conditions and ecosystem productivity influence the foraging behaviour of top predators; and 4) Quantifying the relationship between sea ice changes and the energetic intake of polar bears via changes in prey availability. These investigations will support the training of numerous highly qualified personnel and provide a quantitative framework of data for assessing future changes in arctic ecosystems.