Predator-prey interactions in dynamic arctic ecosystems

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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.