| Summary: | Specialization: Physiology, Cell and Developmental Biology Degree: Master of Science Abstract: Global climate change (GCC) is most pronounced at higher latitudes; to what degree northern migratory fish species can tolerate this change remains largely unknown. Imminent effects of GCC on arctic rivers include warmer water temperatures and changes in the timing, frequency and magnitude of high and low flow events, all of which could reduce fish passage. Arctic char (Salvelinus alpinus), are a salmonid species of great ecological, cultural, and subsistence value, and are among the fish species likely to be impacted by these changes. Based on this, my research aim was to identify life-history and physiological characteristics that would be likely to shape the ability of arctic char to cope with GCC. To this end, in chapter 2, I characterized alternative migratory life-history strategies that facilitate the existence of a char population in a harsh environment. The most significant of these strategies included the earliest documented return migration timing in the Canadian Arctic and a very low annual fidelity (near 0%) which together, reduced fishes exposure to even harsher conditions than those they already faced. In the physiological components of my research I took a comparative approach and conducted experiments on rainbow trout, a well-studied temperate reference species, in addition to arctic char. In chapter 3, I used laboratory simulations to identify potential physiological constraints on the migration of arctic char through current and future thermal regimes that include large diurnal temperature fluctuations. In chapter 4, I revealed transcriptional and biochemical responses of arctic char to these thermal regimes that were indicative of only partially successful compensatory responses in addition to severe heat-stress and disruption of biochemical processes. In chapter 4, I also verified the utility of a suite of transcripts as biomarkers for thermal stress in wild arctic char. Together my research ...
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