Effect of temperature on excess post-exercise oxygen consumption in juvenile southern catfish (Silurus meridionalis Chen) following exhaustive exercise

The effects of temperature on resting oxygen consumption rate (MO2rest) and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise (chasing) were measured in juvenile southern catfish (Silurus meridionalis) (8 40 +/- 0 30 g, n = 40) to test whether temperature has a significant influence on MO2rest, maximum post-exercise oxygen consumption rate (MO2peak) and EPOC and to investigate how metabolic scope (MS MO2peak - MO2rest) vanes with acclimation temperature The MO2rest increased from 647 (10 degrees C) to 160 3 mg O-2 h(-1) kg(-1) (25 degrees C) (P < 0 05) and reached a plateau between 25 and 30 degrees C The post-exercise MO2 in all temperature groups increased immediately to the peak values and then decreased slowly to a steady state that was higher than the pre-exercise MO2 The MO2peak did not significantly differ among the 20,25 and 30 degrees C groups, though these values were much higher than those of the lower temperature groups (10 and 15 degrees C) (P < 0 05) The duration of EPOC varied from 32 9 min at 10 degrees C to 345 min at 20 degrees C, depending on the acclimation temperatures The MS values of the lower temperature groups (10 and 15 degrees C) were significantly smaller than those of the higher temperature groups (20, 25 and 30 degrees C) (P < 0 05) The magnitude of EPOC varied ninefold among all of the temperature groups and was the largest for the 20 degrees C temperature group (about 422 4 mg O-2 kg(-1)) These results suggested that (1) the acclimation temperature had a significant effect on maintenance metabolism (as indicated by MO2rest) and the post-exercise metabolic recovery process (as indicated by MO2peak, duration and magnitude of EPOC), and (2) the change of the MS as a function of acclimation temperature in juvenile southern catfish might be related to their high degree of physiological flexibility, which allows them to adapt to changes in environmental conditions in their habitat in the Yangtze River and the haling River