Effect of thermal acclimation on locomotor energetics and locomotor performance in a lungless salamander, Desmogna- thus ochrophaeus

To determine the effects of thermal acclimation upon locomotor performance and the rate of oxygen consumption (MOl) during activity, small (<3g), lungless salamanders, Desmognathus ochrophaeus Cope, were acclimated to three tempera-tures (5,13 and 21°C) and exercised at various controlled speeds within an exercise wheel while their MOj was measured. MQ2 increased with speed at low speeds (<14cmmin-1). Although animals could sustain greater speeds, MOl did not increase further. These small, exclusively skin-breathing salamanders could increase their MOz 9-11 times during exercise and could sustain nearly half of the oxygen flux expected across a similar surface area of the mammalian lung. However, their maximum aerobic speed was remarkably slow (14cmmin"1) and their net cost of transport remarkably large (15—17 ml Ozg~1km~1). Thermal acclimation affected MQ2 during activity, the maximum sustainable speed and locomotor stamina in different ways. During exercise at 13°C, cold-acclimated animals had a significantly greater MQJ than warm-acclimated animals, but did not differ in stamina or the maximum sustainable speed. During exercise at 21 °C, cold acclimation did not affect the MQ2 significantly, but it decreased the stamina and increased the rate of lactate accumulation. Thus, these results suggest that thermal acclimation of the MOl is not tightly coupled to thermal acclimation of locomotor performance in salamanders