Chemosensory assessment of local predation threats in aquatic vertebrates

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Prey animals are often faced with the conflicting demands of the detection and avoidance of predators and a suite of other fitness related behavioural activities, including foraging, mating and territorial defence. The threat-sensitive predator avoidance hypothesis predicts that prey capable of adjusting the intensity of the antipredator response proportional to the degree of perceived threat should be better equipped to balance these trade-offs. Such models assume that prey can reliably assess local predation risk, yet surprisingly little is known about how prey perceive risk or about the factors that shape these trade-offs. Recent studies in my laboratory have focused on the use chemosensory cues as reliable indicators of risk for a number of prey fishes and how these cues function in threat-sensitive decision-making. In a series of laboratory and field studies, I will examine how prey integrate multiple information sources (i.e., chemosensory and visual cues) and how environmental factors such as resource competition, group size and habitat complexity influence threat-sensitive decisions. I will also examine the role of variability in predation risk over time scales ranging over short-term (days or weeks), long-term (entire growing seasons) or evolutionary (multigenerational) durations plays in the shaping of threat-sensitive trade-offs. Threat-sensitivity models predict that individuals should be able to alter their behaviour in order to compensate for the costs associated with predator avoidance, though this remains largely untested under natural conditions. I will conduct long-term field studies to investigate this hypothesis. Finally, a great deal of recent research demonstrates that anthropogenic pollutants, such as acid precipitation, impair the ability of prey fishes to chemically assess local predation risks. It remains unknown if prey can compensate for the loss of chemosensory inputs by either altering their behaviour patterns or increasing their reliance on other, non-chemical inputs. By improving our understanding of how prey assess and respond to local predation threats in a threat-sensitive fashion, we hope to enhance the ecological validity of environmental assessment and management programs and fisheries stock enhancement efforts.