Spring-fed Wetlands: Important Scientific and Cultural Resources of the Intermountain Region, May 7-9, 2002, Las Vegas, Nevada.

Australian desert spring fishes: their extreme habitats and ecological attributes.

P.J. Unmack

Approximately 190 strictly freshwater fish species occur in Australia, most in wetter northern and eastern areas. Central Australia, despite its aridity, contains 32 fishes of which 12 occur in springs. These springs represent the natural outlets from the Great Artesian Basin, a huge groundwater system that mostly receives recharge from the wetter Eastern Highlands. There are around 600 individually named springs, although many have multiple discrete outlets (up to 400 in extreme cases). Great Artesian Basin springs are categorized into 11 "supergroups" based on geographic proximity. The four supergroups that contain fishes all occur in Central Australia. Dalhousie Springs Supergroup (South Australia) has the highest richness with six fish species (five endemic), followed by Edgbaston Springs (Springsure Supergroup, Queensland) with three species (one endemic). The Lake Eyre Supergroup (South Australia) has two species, although one is only ephemerally present. Finally, Elizabeth Springs (Springvale Supergroup, Queensland) has one species which is endemic. The fish fauna of each spring system differs ecologically due to major geomorphological differences between spring groups. These include overall spring size, height and extent of spring mound formation, discharge volume and spring outflow geomorphology. The result of these differences is that some springs have large pools and streams with fairly constant physico-chemical characteristics, others lack pools, but have smaller discrete outflow channels with moderately constant conditions, and some have miniscule discharges with indiscrete outflows typified by extremely shallow water and highly variable physicochemical conditions. This presentation reviews Central Australian springfishes and focuses on their characteristics allowing survival under extreme physical conditions.