Understanding change in Arctic marine ecosystems: polar bears as ecological indicators

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Predicting the impacts of environmental change on species requires an understanding of reproduction, survival, growth, behaviour, habitat use, foraging, migration, and timing of life history events. Further, early warning indicators are essential for effective conservation and management. The main objective of my research is to identify the mechanisms associated with polar bear population change over time to predict the effects of global warming. The research uses three integrated approaches including satellite telemetry (GPS collars), analysis of tissues that record life history or physiological status, and mathematical modelling. Four polar bear populations are being studied in the Canadian Arctic that reflect different sea ice regimes and rates of sea ice change across the range of ecological conditions that polar bears experience. I am developing movement models using satellite telemetry data that integrate the dynamics of the habitat and searching strategies to identify specific behaviours (e.g., feeding, migration). Satellite telemetry data is also being used to develop regional sea ice models to predict future conditions relevant to polar bears with focus on key periods that affect reproduction and survival. Integration of these data into mathematical models (e.g., dynamic energy budget models, population projection models) allows an improved understanding of population dynamics. Coincident field sampling of tissues that record life history (e.g., tooth annuli, claw shavings, isotopes in teeth by laser ablation, and hormones in hair) are being used to develop new cross-disciplinary insights into polar bear ecology. Using these tissue archives, I will examine how changes in sea ice regimes are associated with nutritional stress in polar bears (e.g., hair cortisol) while distribution, diet, and migration patterns will be examined using isotopic signature. The results will specifically address how climate change affects foraging success and movement patterns of polar bears, and thus may provide a mechanistic understanding of the decline in polar bear body condition associated with demographics. Using different biomarkers along with known histories and movement patterns of the animals, my research will be able to identify patterns associated with changing ice conditions.