The effect of temperature on the resting and post-exercise metabolic rates and aerobic metabolic scope in shortnose sturgeon Acipenser brevirostrum

The effects of acclimation temperature (15, 20, 25 A degrees C) on routine oxygen consumption and post-exercise maximal oxygen consumption rates (MO2) were measured in juvenile shortnose sturgeon (Acipenser brevirostrum LeSueur, 1818). The routine MO2 of shortnose sturgeon increased significantly from 126.75 mg O-2 h(-1) kg(-1) at 15 A degrees C to 253.13 mg O-2 h(-1) kg(-1) at 25 A degrees C. The temperature coefficient (Q (10)) values of the routine metabolic rates ranged between 1.61 and 2.46, with the largest Q (10) values occurring between 15 and 20 A degrees C. The average post-exercise MO2 of all temperature groups increased to a peak value immediately following the exercise, with levels increasing about 2-fold among all temperature groups. The Q (10) values for post-exercise MO2 ranged from 1.21 to 2.12, with the highest difference occurring between 15 and 20 A degrees C. Post-exercise MO2 values of shortnose sturgeon in different temperature groups all decreased exponentially and statistically returned to pre-exercise (resting) levels by 30 min at 15 and 20 A degrees C and by 60 min at 25 A degrees C. The aerobic metabolic scope (post-exercise maximal MO2-routine MO2) increased to a maximum value similar to 156 mg O-2 h(-1) kg(-1) at intermediate experimental temperatures (i.e., 20 A degrees C) and then decreased as the temperature increased to 25 A degrees C. However, this trend was not significant. The results suggest that juvenile shortnose sturgeon show flexibility in their ability to adapt to various temperature environments and in their responses to exhaustive exercise.