Behavioural response of Rana cyanophylictis tadpole exposed to changes in dissolved oxygen concentration

Abstract

To study surfacing behaviour and buccal movement, different stages of the tadpole Rana cyanophylictis life cycle were exposed to changes in dissolved oxygen concentration (DO). Surfacing frequency is inversely related to DO, but the buccal movement is DO-independent. Correlation between DO and surfacing frequency becomes significant in Stage 41, and it suggests that the younger tadpole may utilize the larger body surface (on a unit weight basis) available for respiration. There is a marked increase in surfacing frequency below the critical DO level of 5.8 mg/l. This suggests the occurrence of a physiological mechanism that preferentially uses the aerial respiratory surface over aquatic. Buccal movement is negatively correlated (−0.963) to life stage of the tadpole; however, surfacing frequency is positively correlated (+0.963) to it and both correlations are statistically significant. With a decrease in aquatic respiration, there is a proportionate increase in aerial respiration in the old tadpole.