Bruce C. Chessman
Australian Journal of Zoology 66 (5-6), 317-325, (21 May 2019) https://doi.org/10.1071/ZO18062
KEYWORDS: aerobic scope, Chelodina expansa, Chelodina longicollis, Emydura macquarii, oxygen consumption
Oxygen consumption (
) of Chelodina expansa, C. longicollis and Emydura macquarii (Pleurodira: Chelidae) was measured at rest and during induced exercise at 8, 13, 18, 22, 26, 30 and 34°C. Resting
varied significantly among species, being lowest in C. expansa, which is the most sedentary of the three species in nature, and highest in E. macquarii, which is the most energetic, but active
did not differ significantly among the three species overall. For both Chelodina species, resting
was appreciably lower than expected from regression of
on body mass for non-marine turtles globally, a result that reinforces previous evidence of low resting metabolism in Australian chelid turtles. Active
of all three species at higher temperatures was similar to
reported for active freshwater cryptodires. Resting
of all three species increased similarly with temperature, but active
and aerobic scope did not. In C. expansa and E. macquarii, active
and aerobic scope increased over the full temperature range assessed but in C. longicollis these variables reached a plateau above 22°C. Projected increases in freshwater temperatures in south-eastern Australia as a result of global warming are likely to enhance activity, feeding and growth of the three species (subject to food availability), especially in cooler seasons for C. longicollis and warmer seasons for C. expansa and E. macquarii. However, other aspects of predicted climate change, especially increased drought, are likely to be detrimental.