Biogeographical patterns of endemic diversity and its conservation in Australia's artesian desert springs

Aim: Springs in the Australian arid zone are distinct from other waterways because they house a large number of endemic species. We aimed to assess spatial patterns in endemic diversity at a basin-wide scale and whether environmental features can help to explain them. In doing so, we take the opportunity to summarize the current state of conservation in the system. Location: Great Artesian Basin (GAB), arid and semiarid regions of eastern Australia Methods: We combine data regarding the location of springs with published GIS layers regarding environmental characteristics and a literature review of all species and subspecies documented in the published literature to be endemic to GAB springs. Results: We found evidence of 96 species and subspecies of fishes, molluscs, crustaceans and plants endemic to these springs. The majority of endemic species are invertebrates with geographical distributions limited to a single spring complex (<61 km(2)). Endemic taxa are concentrated in 75 of the 326 spring complexes. Spring complexes with a large number of springs, high connectivity via drainage basins and low rainfall were more likely to contain endemic taxa, but environmental models were poor predictors of diversity. Only 24% spring complexes with high conservation value are within conservation reserves, and the majority of endemic species are unassessed under the IUCN and Australian conservation legislation, particularly the invertebrates. Main conclusions: Diversity in this system is underestimated given the current rate of species discovery and prevailing data deficiency for many taxa. Historical processes and species-specific environmental requirements may be more important for explaining why diversity is concentrated in particular complexes. Almost a decade after this system was listed as endangered, most complexes of high conservation value remain outside of conservation reserves, and the endangered species status of many taxa, and particularly the invertebrates, remain unassessed.