Turbulence decreases the hydrodynamic predator sensing ability of the calanoid copepod Acartia tonsa

The copepod Acartia tonsa is very sensitive to hydrodynamic signals, including those made by approaching predators, and responds with a vigorous escape jump. Whether the presence of moderate turbulence changes this ability to detect hydrodynamic signals was investigated by comparing the response of copepods to velocity gradients created by a siphon flow in turbulent and still water. Turbulence decreased the distance at which A. tonsa initiated escapes from the siphon and increased the capture rate, indicating decreased sensitivity to hydrodynamic signals, but did not trigger unnecessary escape reactions that might produce fatigue.