Ecology of stress in wild fish in a changing world

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The long-term goal of the Fish Ecology and Conservation Physiology Laboratory is to establish a clear understanding of the inter-relationships between the environment and individual-level physiology, behaviour, and fitness. In other words, we are interested in the ecology of stress. Stress is a part of the functional underpinning of ecology and plays a fundamental role in defining animal distribution and abundance. The neuro-endocrine stress axis (particularly the stimulation, synthesis, and release of glucocorticoids; GCs) integrates environmental information that influences life-history decisions such as those related to energy use and allocation, which ultimately influence fitness and survival. We focus on teleost fish, but unlike most previous research, do so in an ecological context using wild fish in field settings. Over the past five years our lab has made substantial progress in understanding stress in wild fish. However, the world is changing rapidly as a result of human activity, which means that fish are increasingly exposed to multiple stressors, some of which are novel. As such, our five-year goal for this NSERC Discovery Grant is to study the ecology of stress in wild fishes in the context of a changing world, attempting to understand (Theme A) how abiotic and biotic factors mediate stress responsiveness and (Theme B) the consequences of stress and stress responsiveness on organismal condition, behaviour, and fitness. The scientific approaches that will be used for hypothesis testing will include extensive experimentation and comparative surveys in natural field (e.g., lakes, rivers) and mesocosm (e.g., experimental ponds and streams) environments. For Theme A we will rely heavily on non-lethal blood sampling combined with electronic tagging. We will evaluate population-specific variation in stress responsiveness by assessing changes in cortisol, the principal GC in teleost fish, and also consider how habitat quality influences GC responsiveness. In some experiments we will expose fish to varied holding environments (e.g., manipulating thermal environment and flow) and evaluate GC responsiveness. For Theme B we will primarily use exogenous cortisol manipulations before releasing fish and observing the consequences of GC elevation. In some experiments we will evaluate how stressors influence wound healing in wild fish, while in other studies we will focus on reproductive success and survival endpoints. We will also manipulate environmental stressors and consider the potential for carryover effects across seasonal and life-history transitions. The proposed research is novel and has the potential to have a substantial influence on understanding ecological processes, particularly in the face of environmental change. The integrative research themes span the fundamental-applied continuum will provide a functional understanding of the effect of anthropogenic environmental change on organisms while elucidating the mechanistic relationships between physiological processes and population declines. For example, the work will reveal whether there is a mismatch between novel stressors and the GC response. The proposed work has substantial scope for training of highly qualified people and will help to ensure that the next generation of scientists has an understanding and appreciation for how human activities influence animal populations and the ecosystem services that these populations provide. In addition, there is considerable opportunity to engage the public and concerned stakeholders and generate knowledge of use to environmental managers.