Relation of oxygen consumption to temperature and time of day in tropical anuran amphibians

Abstract

Oxygen consumption was examined in three species of tropical frogs, Rana blythi, R. chalcanota and R. nicobariensis, at ambient temperatures between 20 and 35�C. Oxygen consumption varied directly with temperature over the entire range studied. The thermal coefficient (Ql0) for oxygen consumption for the three species averaged 2.67 (range 2.49-2.84), which is similar to that of temperate zone amphibians. At 25�C, the resting oxygen consumption of the tropical frogs averaged only 30% of that predicted for ranids on the basis of body weight. Oxygen consumption of R. nicobariensis and R. chalcanota, determined at 30�C in continuous darkness at 15-min intervals for 26 consecutive hours, exhibited an endogenous rhythm with a period of approximately 12 hours. Thus, while these tropical anurans resemble their temperate relatives in some respects, they possess greatly reduced levels of resting oxygen consumption.