Meeting Abstract
P3.48 Saturday, Jan. 5 The effects of acute temperature change on labriform swimming performance in bluegill sunfish JONG, Arianne*; JONES, Emily A; ELLERBY, David J; Wellesley College dellerby@wellesley.edu
Bluegill sunfish are potentially exposed to a wide range of water temperatures. Bluegill swim in the labriform mode at low speeds, switching to undualtory swimming at higher speeds. We investigated how exposure to acute temperature change affected maximal labriform swimming performance in this species. In fish acclimated to 22 °C exposure to lower water temperatures (14 and 18 °C) reduced maximal labriform swimming speed and pectoral fin beat frequency relative to 22 °C. Exposure to temperatures above 22 °C (26 and 30 °C) had no detectable effect on maximal labriform swimming speed and pectoral fin beat frequency. Dissolved oxygen levels decrease with increasing water temperature, potentially limiting performance. Elevating oxygen levels with pure oxygen at 30 °C had no effect on swimming performance, suggesting that dissolved oxygen was not a limiting factor. Total oxygen uptake could be increased beyond the level used during maximal labriform swimming, suggesting that systemic oxygen uptake did not limit labriform swimming performance. Muscle level rather than systemic factors appeared to be limiting maximal labriform swimming speed. Measurements of pectoral girdle muscle mechanical power output in vitro showed that at temperatures above 22 °C the muscle was capable of operating at higher cycle frequencies and generating more power than under in vivo conditions. This suggested that factors other than the intrinsic mechanical properties of the muscle, possibly oxygen delivery at the muscle level, were limiting performance at high temperatures. At temperatures below 22 °C, the pectoral girdle muscle operated at a cycle frequency that maximized power output. This suggested that at low temperatures the mechanical properties of the pectoral girdle muscles set the limits to labriform swimming speed.
