The importance of the cloacal bursae as the primary site of aquatic respiration in the freshwater turtle,Elseya albagula

Abstract

The ability of freshwater turtles to exchange respiratory gases with their aquatic environment is well known and facilitates prolonged dive durations among several species. Three main sites have been implicated in aquatic respiration (skin, cloaca and buccopharynx) yet the relative contribution of each to total aquatic O2 uptake has been poorly examined among Australian chelids. In this study we investigated the diving physiology of Elseya albagula, a bimodally respiring turtle from Queensland, Australia. Through partitioning experiments we tested the hypothesis that the cloacal bursae are the main site of aquatic O2 uptake in this species. Aquatic oxygen uptake accounted for 70 ± 8% of total oxygen requirements demonstrating the impressive ability of the species to respire underwater, although this was negatively correlated with body mass. Further, the cloacal bursae were found to account for 48% of total aquatic oxygen uptake, providing strong evidence that they are the primary site of aquatic respiration in E albagula.