Meeting Abstract
We exposed bluegill Lepomis macrochirus to turbulence and no turbulence after the injection of gallamine triethiodide (Flaxedil, non-depolarizing neuromuscular blocking agent), lidocaine (afferent nerve blocker) or saline solution (control) into the dorsal fin erector muscles. We expect that when motor control or afferent information are compromised, fish exposed to turbulence will show no activity in the erector muscles and erratic behavior will occur. We quantified fin erector muscle activity using electromyography and high-speed video of dorsal and lateral views. Under control conditions, lateral video kinematic data show that the erector muscles of the spiny dorsal fin are responsible for moving the fin up, as onset and offset of muscles coincided with changes in fin height. Under turbulent conditions, fish displayed erratic behavior when afferent information was removed, suggesting its inability to effectively control the dorsal fin. This effect was only partially seen in Flaxedil treatments. Electromyographic recordings show higher magnitude of muscle contraction during turbulence in both the control and Flaxedil treatments but not in the lidocaine treatment. Frequency and duration of contraction were kept constant under turbulent and non-turbulent conditions for both lidocaine and Flaxedil, however they were significantly different under control conditions. We can conclude that when sensory information is removed the fish is unable or unwilling to erect the spiny dorsal fin to recover stability. When a muscle relaxant is applied, there were some changes in muscle recruitment indicating that not all muscle fibers had been completely blocked. Bluegill rely on the spiny dorsal fin deployment to correct positioning in the water column when faced with turbulence and sensory information is essential to avoid overcompensation.
