A thermal profile of metabolic performance in the rare Australian chelid, Pseudemydura umbrina

Abstract

Thermal performance curves are useful for predicting how organisms might respond to environmental change, and are becoming increasingly applicable for ectothermic animals threatened by climate change. Here we present a thermal performance curve for the critically endangered western swamp turtle (Pseudemydura umbrina) based upon measurements of O2 consumption and CO2 production obtained by flow-through respirometry at temperatures between 15 and 30°C. Standard metabolic rate was significantly higher at 30°C (0.030 mL g–1 h–1 O2, 0.021 mL g–1 h–1 CO2) than at 20°C (0.007 mL g–1 h–1 O2, 0.006 mL g–1 h–1 CO2) and the 20-30°C Q10 for O2 and CO2 were 4.60 and 3.55 respectively. Oxygen consumption rates at 15°C and 25°C were 0.002 (±0.000) and 0.018 (±0.000) mL g–1 h–1, with a corresponding Q10 of 9.21. Beyond ~30°C there was a decline in physiological performance, which was supported by activity patterns reported for P. umbrina in the literature.