Supervisors: Michael Power and Jim Reist
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As a cold-water adapted fish, Arctic charr is especially at risk to climate change, particularly with respect to a reduction of their diverse ecological specializations. To initiate a better understanding on the changing fate of this cold-water adapted fish under rapid warming, I investigated Arctic charr biological responses to climate variation via a long-term site-specific database1 and a latitudinal gradient2. I assessed temporal variation in biological characteristics of the Hornaday River (NWT) anadromous Arctic charr population and linked these with environmental drivers through 15 years of data. Age-specific differences suggested that the coupling between growth and environmental fluctuations varied by life stage. I found an age-related pattern of decreasing importance of temperature as a determinant of size and increasing age-related importance of precipitation driven nutrient availability to fuel growth and maturation. In a spatial context, I analyzed 66 populations of Arctic charr across a 37º latitudinal gradient from eastern North America to test for the countergradient hypothesis as an explanation in seasonally adjusted growth rates. Lacustrine Arctic charr demonstrated countergradient support, whereas anadromous charr exhibited equivocal evidence. My research has provided unique insights on attributes that influenced differential growth, information relevant to predict the effect of long-term climate change. I actively established a baseline, reference dataset that are crucially needed in northern areas, which more recent and future data may be compared. This is an initial step toward a direction I intend to pursue, through a combination of local to large spatial and temporal studies and one to multi-species, to include the connectivity of Arctic foodwebs. An ecosystemic approach is the foundation to comprehend the coming storm that will be relevant for the northern fisheries management.
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