The Green Review

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Universities play a crucial role in achieving a sustainable future, especially through their research. Considering this, we are excited to highlight individuals and groups at UNB that have dedicated their time to pursuing sustainability-related research. Know someone who should be a Sustainability Research Champion? Let us know at sustain@unb.ca.

Our newest Sustainability Research Champion is Emily Williams, a graduate student at the University of New Brunswick Saint John.

Seasonal changes in the heat tolerance of heart function in Atlantic and Arctic fishes with different overwintering strategies

My research focuses on understanding how changes in seasonal temperature influence the heart function in Atlantic and Arctic fishes. Fishes are ectotherms, meaning their body temperature is set by that of the surrounding water. Temperature is a major environmental factor influencing most major bodily processes and, consequently, the overall performance of the animal. Aquatic environments, especially in northern climates, often experience extreme seasonality resulting in large temperature variation over the course of a fish’s lifetime. This thermal variation can challenge critical physiological processes in fishes, such as heart function.

I have been carrying out two studies. The first is a detailed laboratory study on the thermal acclimation of the heart and its control by adrenaline, a central hormone involved in the fight-or-flight response, in marine and freshwater fish (cunner, brook trout, and lumpfish) acclimated to three seasonally relevant temperatures; and, second, a field study in the Kitikmeot region in central Nunavut on the seasonal acclimation of the heart and adrenaline regulation in wild Arctic marine and freshwater fishes (Greenland cod, lake trout, and fourhorn sculpin). Overwintering strategies can vary among species; those employed by my study species range from winter active to winter dormant, so it is important to consider the influence of these distinct winter responses on the seasonal changes in heart performance. The goal of these studies is to provide comparative information on the flexibility of the heart’s performance and tolerance across variable seasonal temperatures among a diverse range of fishes, to improve our understanding on how different species of fishes’ cope with the temperature variation that accompanies changing seasons.

How does your work intersect with sustainability?

As climate conditions become more variable, especially in winter and/or regions such as the Arctic that are changing rapidly, it is becoming increasingly more important to understand the effects of temperature variation on vital temperature sensitive functions like heart rate. This is particularly important given the economic, ecological, and cultural importance of several of my study species as detailed knowledge of how temperature and environmental variation affects their health and well-being (i.e. their physiology) is needed to inform evidence-based conservation efforts that allow for the long-term sustainability of these populations.

What impact do you hope this research will have?

I see my research as a piece of a much bigger picture. My work will provide important information on the ability of species to cope with changing and increasingly variable temperature conditions and can be used alongside several other crucial studies (i.e. movement studies) to help make evidence-based conservation and management decisions. For example, my recent work on Arctic lake trout showed that in the height of summer they may be experiencing temperatures at or even above their temperature limit for heart performance. When paired with our tracking studies, we will be able to see how these extreme temperatures are impacting the function and movements of lake trout throughout the watershed and their abundance in certain lakes in the region throughout the season. Together, this information can help identify times of year when this population of lake trout may be particularly vulnerable and help us assess how they will fair with increasing water temperatures and temperature variability.

Where can people find more information about your work?

See the recent article from UNB for more information.