Effects of Body Temperature, Mass, and Activity on Aerobic and Anaerobic Metabolism in Juvenile Crocodylus porosus

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Abstract
Resting oxygen consumption (V̇o2 rest) and active oxygen consumption (V̇o2 active) of juvenile Crocodylus porosus increased significantly with body temperature (Tb) and had mass exponents of 0.702 ± 0.160 and 0.839 ± 0.530 (mean ± 95% confidence interval), respectively. Compared with other reptiles, V̇o2 active of C. porosus was low. Both V̇o2 rest and V̇o2 active had high thermal sensitivities (Q10) and reached peak levels between 30 and 33 C, a range that overlaps both preferred Tb range and summer water temperatures. This may enable crocodiles to be most active and to recover rapidly from activity within a narrow Tb range experienced throughout the day in the field. Anaerobic capacity showed no significant trend with changes in body mass or Tb. During activity to exhaustion, aerobic capacity increased with Tb while anaerobic capacity remained thermally independent. Consequently, the total metabolic input and proportion of energy supplied aerobically increased with Tb to a maximum at 33 C and may explain the increased duration of activity at higher Tb.