UBC Theses and Dissertations
Effects of contaminants and climate change on the health of western Arctic beluga whales (Delphinapterus leucas) Crichton, Ellika
The Arctic is currently undergoing a period of transformation brought on primarily by climate change. Climate-induced changes in sea ice have led to changes in primary productivity, prey abundance and distribution, and habitat availability. There are concerns that the Arctic could be ice free by 2040, meaning that there is urgency in determining the impacts that climate change will have on the organisms that inhabit the Arctic. Climate change, however, is not the only pressure that marine organisms are facing. Contaminants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and mercury (Hg) have been identified as contaminants of concern to wildlife in the Arctic. Little is known about the interaction between contaminants and climate change, but concerns have arisen that the two stressors may exacerbate each other. The goal of this thesis is to add to our current knowledge of the impacts of contaminants and climate change on the health of western Arctic beluga whales and to explore the potential interaction between the two stressors. I examined the mRNA expression of 12 genes involved in detoxification of xenobiotics, nutritional stress and metabolism as a proxy for beluga whale health. The relationship between mRNA expression and contaminant burdens, stable isotopes and fatty acid signatures, sea ice levels and body condition metrics were examined in liver and blubber samples taken between 2008 to 2017. A principal component analysis on gene expression resulted in factor 1 explaining 78% percent of the variance for blubber and 90% of the variance for liver. Factor 1 was found to be significantly related to ẟ¹³C in blubber. Analysis of fatty acid profiles using PCA revealed inter-annual clustering of the year with the highest sea ice extent as well as the year with the lowest sea ice extent. Analysis of individual genes revealed that sea ice extent, fatty acids, length, ẟ¹³C and Hg may contribute most to the overall variation in gene expression. Results suggest that physiology of Beaufort Sea beluga whales are affected by a combination of climate-induced changes in foraging patterns and environmental contaminants.
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