Do habitat degradation and chemical alarm cues alter the escape behavior of a schooling coral reef fish?

Escaping predation is essential for species survival, but prey must effectively match their response to the perceived threat imposed by a predator. Fish evaluate their surroundings using a multitude of sensory stimuli, including olfactory, visual, auditory, and mechanical cues. Following a predator attack, fast-start responses are used to evade the predator in range of taxa, including fishes, sharks, and larval amphibians. These responses are a high-energy, anaerobically fueled burst of movement starting either from rest or routine swimming and are thought to be initiated by Mauthner cells and other reticulospinal neurons in the brainstem neural escape network. Further, while evidence suggests that habitat degradation alters the perception of conspecific chemical alarm cues that act as a pre-warning of increasing ambient threat, we are currently unsure how these changes will influence antipredator behavior in social fishes. To investigate this question, we examined how habitat degradation (i.e., cues of healthy versus degraded coral) and conspecific chemical alarm cues modulate the escape response of schools of the blue-green Chromis damselfish, Chromis viridis. Our results indicate there was no effect of either coral health or alarm cue on fast-start performance. These results suggest that C. viridis maintains social communication despite changing coral health. In fish schools, individuals depend on social cues to survive predator attacks. This study increases our understanding of the factors that modulate escape behavior for animals that live in a social context and how these behaviors may shift in response to degrading habitat conditions.