| Summary: | Arctic surface air temperatures have been warming at twice the global rate, making it one of the most susceptible regions to current climate change. Effects on cold-adapted aquatic species, such as the culturally and ecologically important Arctic charr (Salvelinus alpinus), are difficult to anticipate and may vary depending on site-specific attributes. Temperature has a direct influence on aspects of species’ fitness, including growth, reproduction and, ultimately, survival. Previous research on temperature-growth patterns in Arctic charr has yielded variable results, particularly for studies observing these patterns in the wild. Two field-based studies are presented in this thesis, in an attempt to better understand temperature-growth patterns for wild populations of Arctic charr. In the first study, individual measurements of annual, or within-season growth were determined from tag-recaptured Arctic charr and examined in relation to summer sea surface temperatures and within-season capture timing in the Ungava and Labrador regions of eastern Canada. Differences in among-year growth were significant for Ungava Bay Arctic charr, with growth being positively correlated with temperature. Growth of Labrador Arctic charr did not vary significantly among years. Regional comparisons demonstrated that Ungava Arctic charr had significantly higher annual growth rates, with differences among years in all regions being positively correlated with temperature. Within-season growth rates of Labrador Arctic charr peaked in June, declined toward August, and were negatively correlated with the length of time spent at sea and mean experienced sea surface temperatures. A quadratic model relating growth rate to temperature best explained the pattern of within-season growth. The higher annual growth of Ungava Bay Arctic charr was attributed to the high sea surface temperatures experienced in 2010-11 and the localized differences in nearshore productivity as compared to Labrador. Results suggest that increases in water temperature ...
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