Effects of variations of osmolarity on behavior in Leptodactylus macrosternum Miranda-Ribeiro, 1926 (Leptodactylidae, Anura, Amphibia)

Amphibians experiencing evapotranspirative water loss may suffer dehydration. Another difficulty is their limited tolerance to brackish water. This study aimed to investigate the effect of water salinity on behavior (activity and water conservation posture) in Leptodactylus macrosternum, in normally hydrated animals with urine in their bladder, in normally hydrated animals without urine in their bladder and in dehydrated ones with urine removed from their bladder. Experiments were filmed, behaviors were registered, and a Behavioral Dehydration Protection Index (BDPI) was calculated, using a weighted average of the postures. A GLM and Kruskall Wallis test was performed with Dunn's multiple comparisons test to evaluate the effects of osmotic gradient stress on BDPI. It was found that emptied bladder and aerial dehydration did not influence BDPI (p = 0.832 and p = 0.142, respectively), contrary to what is seen in the literature. The different osmotic media had a significant effect on BDPI (p = 0.0003).