Sensory and cognitive ecology of risk assessment in a changing world

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Most organisms live in environments that have been altered by humans via habitat destruction, the spread of exotic species, harvesting, pollution or climate change. These changes can alter the delicate balance between predators and prey, by altering the way prey can detect, recognize or assess the risk associated with potential threats. These situations occur if (1) the new environment itself masks the cues used by prey to detect predators; (2) a novel stressor or toxic compound prevents prey from properly recognizing a predation threat; or (3) prey misjudge a risky or safe situation because they use information that was reliable in their past environment, but no longer relevant in the modified one. ******In this grant, I will investigate if cognitive or behavioural plasticity, two traits put forward as main predictors of organism success, allow prey to avoid being caught within the context of the three scenarios outlined above. My work focuses on fish and I typically use stressors that are timely and of economic importance. A perfect example of environmental masking (scenario 1) occurs in coral reefs, where some fish species cannot detect alarm cues when they are surrounded by dead reefs (coral degradation). These chemicals are crucial as they mediate most antipredator responses. I will investigate if these fish can improve their odds of surviving by eavesdropping on other fish species nearby. If risk information can be obtained from other species, then they should have better odds despite their handicap. After last summer, 1/3 of the Great Barrier Reef corals are dead or dying. Many species are forced to survive in this habitat and their fate is currently unknown. A stressor known to cause a dramatic increase in mortality of fish is boat noise, which prevents fish from responding to predators, even when facing imminent death (scenario 2). Canada desperately needs to provide regulations for underwater noise pollution, a difficult task when so little is known. I will first determine the spatial scale for which this mortality issue arises, using species of economic importance to Canada. I will test if the noise handicap can be alleviated via habituation (can they become accustomed to it), or via anticipation (can they avoid it if they can predict it). This project will also tell us about the longer-term costs of noise exposure on fish growth and mortality. Finally, I will address scenario 3 by testing if early-life conditions can create a learning bias that allows prey to be less impacted by environmental change. For example, if prey experienced predation risk as embryos, are they more likely to treat unknown threats (eg, invasive predators) as potentially dangerous? Conversely, if they are exposed to safe environments, would they be less likely to treat humans as potential threats, or be quicker to habituate to them? It is critical for us to understand the extent to which prey can compensate and thrive in impacted environments. **