Swimming speeds of grass carp in response to turbulence

In this experimental series we studied the swimming capabilities and response of grass carp (Ctenopharyngodon idella) larvae to flow turbulence in a laboratory flume. We compared three different experimental configurations, representing in-stream obstructions commonly found in natural streams (e.g. a gravel bump, a single vertical cylinder, and patches of submerged rigid vegetation). Grass carp larvae (post gas bladder emergence) were introduce to each experimental configuration and subjected to a variety of hydrodynamic forces of different magnitudes and scales. We varied the flow velocities and water depths and found threshold values of turbulent kinetic energy and Reynolds stresses that triggered an apparent response in larval trajectories, and we estimated horizontal and vertical swimming speeds for each flow condition.