The role of behavioural plasticity in shaping the responses of organisms to the cumulative effects of multiple stressors.

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Behaviour mediates interactions between an individual and its environment. Of the traits that influence the ability of an animal to cope in response to rapid environmental change, behavioural plasticity (how an individual varies in its responsiveness across contexts and over time) plays an important role in how animals respond to environmental change. Given that individuals constantly face multiple stressors at the same time, it is challenging to determine how and why individual variation in responsiveness to stressors influences performance, reproduction and survival. My research program aims to apply and test information on how and why some individuals respond better than others to altered environments to predict how future developments in rapid environmental change will affect population size and stability. As objectives, my research group will determine: 1) how variation in behavioural plasticity - as defined by Exploration tendency, Neophobia, and Aggression (ENA) - is altered by key environmental (abiotic and biotic) factors; 2) whether variation in responsiveness affects performance (foraging, anti-predator, movement behaviour); and 3) the consequences of these response-performance relationships to growth, reproduction and survival modeled under multiple ecological scenarios. To pursue my research objectives I will be using relevant and emerging stressors within ecological systems characterized as human-induced rapid environmental change. Using a local population of yellow perch (Perca flavescens) raised under a spectrum of semi-wild to wild conditions, I will examine both within- and among-individual variation in behavioural types (ENA) under multiple real-world stressors (temperature, oxygen saturation and heavy-metal toxicity), and investigate how these stressors affect the movement ecology (spatial distribution patterns) of individual perch in relation to risk-sensitive foraging, their growth and survival. Using stocks of lake-bound Atlantic salmon (Salmo salar) approved for reintroduction into Lake Ontario, I will explore stock-related differences in behavioural and physiological (skin-pigmentation/stress hormones) coping under both captive and semi-natural settings, and then assess their ability to forage effectively under varying risks of predation and competition to evaluate if plasticity within stocks differs and confers differential fitness between stocks. Using an aquaculture-based stock of Pacific Chinook salmon (Oncorhynchus tshawytscha) with known genetic pedigree, I will investigate whether male reproductive strategies (sneaker vs. normal males), that already possess distinct behavioural characteristics, can be altered by the rearing environment capable of affecting fish growth rates and competitive abilities. For each project I will develop individual-based or system-dynamics models, both ideal methodologies in understanding the behaviour of complex systems over space or time, to determine how individuality in stressor-mediated responses scale up to population-level effects during various spatiotemporal or management-ecological scenarios. An understanding of how individuals differ in their behavioural response to different stressors, and how these differences might interact within variable environments and affect population persistence is crucial for understanding how and why certain species succeed or fail in novel environments. Combining these different individual-based approaches with ecological-scenario modelling can help to identify the key processes and driving forces involved in populations exposed to multiple environmental stressors, significantly contributing to both fundamental ecological and economically relevant applied research.