An integrative approach to stress physiology in fish

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The long-term objective of my research program is to understand the physiology of stress in fish. Most animals, including fish, regularly face environmental challenges that threaten their homeostasis. The initiation of a coordinated suite of behavioural, neuroendocrine and cellular events, collectively termed a stress response, allows the animal to respond to such stressors. Despite the importance of stress responses to the survival and fitness of individuals and populations, our knowledge of how they are regulated and integrated with other physiological systems remains limited, particularly during chronic stress. Moreover, the field of stress physiology is becoming more complex as evidence accrues for early life adversity and intergenerational effects of stress in shaping the stress physiology and behaviour of the next generation.*** The proposed research will use chronic social stress and exposure to acid-base challenges to probe the physiology of stress in rainbow trout and zebrafish. Juvenile salmonid fish establish social hierarchies in which individuals of higher rank profit (e.g. grow better) at the expense of lower-ranking fish. Low growth rates reflect anorexia and remodelling of liver metabolism, and we will identify the regulatory pathways responsible for these effects. Subordinate fish also experience persistent elevation of the stress hormone cortisol, triggered by the presence of the dominant fish. These high cortisol levels disrupt stress axis function, and we will analyze the mechanisms underlying this dysregulation. Because cortisol is both a stress hormone and a regulator of salt, water and acid-base balance in fish, we will study cross-talk between these two functions in the early development of zebrafish, aiming to understand how early life adversity shapes responses to stressors and acid-base challenges later in life. We also aim to identify the mechanisms through which fish sense acid-base challenges and initiate appropriate compensatory responses.*** Collectively, the proposed research will advance our fundamental knowledge of the physiology of stress in fish. Fish can be subjected to multiple stressors both in the natural environment (e.g. angling, environmental pollutants, climate change) and in aquaculture settings (e.g. high holding density, handling, social interactions). Understanding how fish respond to these multiple stressors is critical to improving the management of both wild and aquaculture species.