Life Sciences Seminar: Physiological adaptations of fishes to changing ecosystems

Physiological adaptations of fishes to changing ecosystems

Dr. Ryan Shartau
Research Scientist with Fisheries and Oceans Canada
Pacific Biological Station
Ecosystems Science Divisions

Animals experience changes in their environment; this requires them to elicit an appropriate physiological response to tolerate these changes. This talk will discuss two projects that employ molecular, cellular, whole animal, and field-based approaches to investigate the physiological adaptations used to cope with severe environmental challenges. This work demonstrates the use of a novel strategy of acid-base regulation in fish and reptiles that allow them to tolerate CO2 tensions exceeding 200,000 µatm, which may be associated with the evolution of air breathing in vertebrates.

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Abstract:
Extreme environmental challenges occur worldwide, yet many animals can tolerate, and even thrive in such environments due to their physiological adaptations. Elucidating the physiological mechanisms that underlie these responses depend on understanding the environmental conditions in which they occur. My research links the molecular, cellular, and whole animal responses to environmental change, and how this contributes to the diversity and evolution of vertebrates; in this talk, I will share findings from two projects that utilize this approach. In many aquatic systems, CO2 tensions are very high, with some exceeding 200 times atmospheric levels; for many fishes this poses severe challenge to acid-base regulation. My work demonstrated that fishes in these habitats possess a novel strategy of acid-base regulation, termed preferential intracellular pH regulation, allowing them to fully protect intracellular pH of heart and brain despite up to a 1 pH unit reduction in blood pH, which allows them to survive CO2 tensions of 200,000 µatm; a physiological phenomenon not previously observed. Further investigations into preferential intracellular pH regulation revealed it is also used in developing alligators and turtles to protect embryos from environmental stress; together my work suggest that this strategy plays an important role in the evolution of vertebrates. My other project investigated the response of salmon to toxic microcystin-producing cyanobacteria in coastal British Columbia where mass mortality events have been documented at salmon farms. As part of an industry-government partnership I directed, the molecular and physiological effects of microcystin exposure under environmentally-relevant conditions were investigated. I demonstrated acute microcystin exposure induced changes to genes associated with health and metabolism, and led to the rapid appearance of severe hepatic lesions. Equally important, I documented the persistent and widespread presence of microcystins and other algal toxins throughout southern British Columbia over a three-year period, providing the first insight into the potential risk posed by harmful algae in this region. Finally, my future research plans will be discussed, which involves investigating how natural and anthropogenic environmental stressors affect physiological responses, particularly with a goal of understanding the molecular mechanisms of acid-base and ion regulation in fishes. I am also interested in exploring if maternal exposure to stress events alters the development of progeny, which may provide insight into short-term adaptation to rapid environmental changes.

Speaker Bio:
Ryan Shartau is a Mitacs Elevate Postdoctoral Fellow at the University of Prince Edward Island and an Affiliate at Vancouver Island University. He is originally from Calgary Alberta Canada and completed his PhD at the University of British Columbia investigating the acid-base response of fish and reptiles to high environmental CO2, with much of this research taking place in Brazil, Vietnam, Texas, and Mississippi. Following his PhD, Ryan took up a Visiting Fellowship at the Government of Canada’s Pacific Biological Station investigating the molecular and physiological effects of exposure to toxic cyanobacteria in salmonids. In his current role as a Mitacs Elevate PDF, he looks at the transcriptomic responses of Atlantic Salmon to algal toxins to develop molecular biomarkers to assess the health impacts of exposure. He was recently awarded a prestigious Natural Sciences and Engineering Research Council (NSERC) of Canada Postdoctoral Fellowship to investigate how maternal exposure to aquatic toxins alters developmental programming in fish.

Intended Audience:
Undergraduates, graduates, and experts. Those with interest in the topic.

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