Tempereature tolerance and developmental phenotypic plasticity in early life stage fish

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Global climate change is contributing to a general trend of increased temperatures in river systems worldwide. Consequently, temperature increases in local aquatic environments driven by human sources may be inducing intense selection pressures on fish in these ecosystems. How animals cope with changes in their environment will predict how populations respond to these future conditions. While we understand a great deal about acute responses to warming and cooling in fish, we know much less about how thermal history might promote physiological adjustments that result in protection from chronic warming or episodic heating events. My research program focuses on the phenotypic responses of early life stage fish, and how exposure to elevated temperature may enhance protection from future thermal challenge. To address this, I intend to characterize the magnitude and timing of thermal protection acquired during development of larvae and juvenile fish, and as a result of pre-exposure to increased temperatures. I will also describe the proportion of thermal protection that is permanent (i.e., a result of developmental plasticity, as opposed to through acclimation) when eggs or larval fish are reared under different thermal regimes. Examining, then, this phenotypic plasticity to elevated temperatures over the broader context of life history characteristics, I will test the hypothesis that longer generational times in fish will be associated with a propensity for reversible phenotypes, as there may be less selective pressure to permanently adjust to current conditions. *** In BC, there is great interest in both the long-lived, primitive sturgeons, and more ephemeral, but hugely ecologically and economically important salmonids, that represent social and cultural icons on the West Coast. For the studies outlined here, I will focus on these two groups, sturgeon and salmon, as these anadromous, migratory fishes have substantially different life history strategies that may have contributed to different approaches to thermal tolerance. This work will provide knowledge that will help protect endemic stocks and mitigate climate change effects on species with great cultural, socioeconomic and ecological value to British Columbians. The unique, cutting-edge RAS facilities and location of Vancouver Island University are exceptionally well suited to begin this work, and over the course of five years, I intend to train 7 undergraduates, 2 M. Sc. students, and a Ph.D. student.