Biodiversity and biogeography of groundwater invertebrates in Queensland, Australia

Groundwater systems, traditionally considered lifeless conduits of water (Hancock and Boulton 2008, Schulz et al. 2013), are now known to provide critical habitat for a diverse range of fauna collectively called stygofauna. Stygofauna communities can have significant conservation value as exemplified by relatively high levels of endemism and biodiversity. Despite this the biogeography and taxonomic diversity of stygofauna communities largely remains undocumented. This paper describes the development and interrogation of a state-wide database of 755 samples from 582 sites, and reviews the current knowledge of stygofauna biodiversity and biogeography across Queensland (north-eastern Australia). Queensland is known to host 24 described families of stygofauna with stygofauna composition broadly consistent with other regions around the world. However Queensland assemblages tend to be unusually rich in both oligochaetes (16% cf. 2%) and syncarids (12% cf. 4%). Associations between stygofauna taxonomic richness and key environmental variables were consistent with many general assumptions of habitat suitability. However there were also notable exceptions, including stygofauna records from: groundwater 60 meters below ground level; groundwater with electrical conductivity above 50,000 μS/cm, and; both highly acidic (pH 3.5) and alkaline (pH 10.3) environments. These exceptions clearly demonstrate that strict adherence to general assumptions about habitat suitability when planning sampling activities may mask the true diversity of groundwater ecosystems