Temperature Effects on Aerobic Metabolism and Terrestrial Locomotion in American Alligators

• American Alligators were hatched and used for study
• Kept animals at 15, 25 or 35° C overnight before testing
• Measured mean VO₂ at each temp.
• Used treadmill walking to evaluate VO₂ contribution to total metabolism
• Measured VO₂ via open-flow calorimetric system before, during and after exercise
• Monitored T_b throughout treadmill activity
• Max. VO₂ was determined from last 3 min. of 8 min. exercise bout

• Max. VO₂ 10X higher at 25 and 35° C than at 15° C
• Avg. recovery VO₂ during 30 min. post-exercise was 6X higher at 25 and 35° C than at 15° C
• Distance traveled was 3X higher at 25 and 35° C than at 15° C
• Q10 for resting VO₂ = 2.8 b/w 15 and 25° C , 2.3 b/w 25 and 35° C
• Factorial Scope: <2 at 15° C, >6 at 25° C and 2.5 at 35° C
• Plateau in Max. VO₂ b/w 25 and 35° C (thermally insensitive)
• Distance traveled did not increase at high temps

• The broad plateau (b/w 25 and 35° C) allows alligators to be active at wide range of temps. in nature
• Suggested max. VO₂ plateau may be due to fact that the alligators exert the same energy at exercise b/w the upper temp. region
• May also explain their broad geographical range
• After exercise, the VO₂ did not return immediately to pre-exercise levels (EPOC= excess post-exercise O₂ consumption). This was due to mitochondrial O₂ consumption. (resynthesis of ATP and glycogen, removal of lactate, and increased T_b)
• Suggested that this heightened VO₂ attributed to EPOC was part of the energy costs of the exercise itself and should be included in the temp. effects on the non-sustainable activity
• Suggested a more inclusive estimate of energetic cost of exercise would encorporate EPOC
• (VO₂ from exercise + recovery VO₂) / total distance traveled