Waves affect the escape response of juvenile coral reef fish

Data set for Roche (submitted) Waves affect the escape response of juvenile coral reef fish 1. Fish often escape from predators with a burst of speed (fast-start responses). In laboratory studies, these responses are always measured in stationary water. However, water motion due to waves and currents is ubiquitous in many aquatic systems. 2. In shallow marine habitats, wave action creates unsteady water motion that varies spatially and temporally. This likely affects the ability of fish to escape, especially when they are small. Since body depth is thought to improve postural control and stability, I examined how wave-driven water flow affects the escape response of juvenile coral reef fish in three species of Pomacentridae with different body morphologies. 3. Escape responses were elicited under static or unsteady flow conditions. In unsteady flow, all fish covered a greater distance and reached a higher speed and acceleration when escaping in the direction of the water flow. However, compared to static flow, unsteady flow had no detectable effect on maximum escape performance. 4. Fish took longer to respond to the stimulus in unsteady compared to static flow. This effect differed between species. The fusiform-shaped species responded more slowly in unsteady than in static flow. This difference was less pronounced in the species with an intermediate body depth and absent in the species with a deep body. The deep-bodied species also tended to orient itself more directly into the water flow and was less displaced by water motion. 5. Response latency is a major determinant of escape success, so postural disturbances from unsteady water motion might reduce the ability of some fishes to evade predators during juvenile settlement. This could have important implications for the distribution, abundance and recruitment of reef fishes across spatial and temporal scales.