Polar Bears International Isotope Study

Measurements of naturally occurring stable isotopes in animal tissues can be used to monitor the diets of wide-ranging species, such as polar bears, that cannot be directly observed. Stable isotopes of carbon and nitrogen are incorporated into organisms at differing rates depending on their prey and trophic level. Basically, Stable isotope analysis is based on the principle "you are what you eat." These isotopes are increasingly being used to understand changes in ecosystem structure.

Over the last 30 years, sampling in the Southern Beaufort Sea has collected claw shavings (i.e., collected with nail trimmers) and hair samples from live-captured polar bears. Using stable isotopes of carbon and nitrogen preserved in these two tissues, we will examine ecosystem dynamics relative to sea ice conditions, climate indices, and population trends.  We will explore the utility of using stable isotopes to understand changes in the distribution, diet, and migration patterns of polar bears in the Southern Beaufort Sea. This study exploits new methods but it is hoped that the results will explore how climate change affects foraging success and movement patterns of polar bears and may provide insight into the decline in polar bear body condition associated with demographic changes and the documented population decline. New technology introduced to the Canadian Center for Isotopic Microanalysis at the University of Alberta (Canadian Foundation for Innovation) allows fine-scale (1-30 microns) in situ sampling of isotopes within samples (i.e., hair and claws). This technology, typically used in geochemistry, is a powerful new tool for biological samples. Using the fine-scale ion microprobe we will be able to sample stable isotopes of carbon and nitrogen along each hair and nail providing us with a timeline of feeding and movements. We will also use more conventional methods of whole hair and nail analysis to develop monitoring methods for polar bear population status. This project builds on existing expertise in isotope analyses at the University of Alberta.