Meeting Abstract
Fish encounter complex hydrodynamic environments while swimming and probably rely on multiple sensory systems to adjust their swimming and to remain stable in unsteady flows. It is unclear how the lateral line and vision contribute to a fish’s ability to compensate for different types of unsteady flows, including horizontal vortices (like those shed by waterfalls, or over the top of rocks). Preliminary experiments showed that bluegill sunfish (Lepomis macrochirus) were stable in horizontal vortices with and without their lateral line and visual systems. Here, we challenged fish in a flow tank to more frequent horizontal vortices generated by a custom-made flapper and faster flow rates to continue testing the relative importance of these sensory systems in fish swimming. To test vision, fish were filmed under regular or infrared light and to test the lateral line system, fish were treated with cobalt chloride to deactivate this sensory modality. A fish was positioned behind the flapper (flapping frequency = 1, 2, or 3 Hz) while swimming at one of three speeds during each trial and recorded with three high-speed cameras to obtain the fish’s position relative to the flapper over time. Overall, fish recovered quickly from the flapper action and differences in swimming movements were observed under the various flow and sensory conditions and will be discussed. Therefore, we continue to support that bluegill sunfish are relatively stable in horizontal vortices likely due to passive properties of their bodies, but sensory input from the lateral line and visual systems contribute to regaining stability after exposure to unsteady flows.
