Unravelling life history of the Inland Freshwater Crab Austrothelphusa transversa in seasonal tropical river catchments

Few freshwater aquatic species have ecological traits that deal with the vagaries of flow in ephemeral tropical rivers. In northern Australia, the tropical freshwater crab, Austrothelphusa transversa (von Martens, 1868) is a conspicuous species that occupies seasonal rivers, where it is thought to estivate in underground burrows while waiting for summer rain. During a survey in seasonal river catchments the first photographic evidence was obtained of an estivating female crab containing 42 crablets under the abdomen plate. Uncovering this female with crablets suggests that egg development progressing to crablets occurs during the dry season estivation when crabs are underground and no water exists in river channels; if this is the case then this female crab may have been waiting for rain, to emerge and successfully continue the life cycle in water. Since 2012 the southern Gulf of Carpentaria has experienced below average rainfall, contributing to no or short flow periods over most of the landscape. In light of modelled climate change (which predicts an increase in the number of years with low rainfall in northern Australia), along with intensification of agriculture development, it is postulated that reduced access to water might become a regular challenge for this crab species. With more data the IUCN Red List status (Least concern) for this species might need further review.