3 – Fish distribution, status and threats 37 and are comparatively secure as this spring complex is reserved as a national park and fenced to exclude stock. Cattle, pigs and camels all severely damage and deplete springs through pugging, wallowing and drinking (Fig. 3.3). In addition, the invasive fish species gambusia or mosquitofish has not been recorded in the Diamantina catchment in Queensland. Two species of endangered and endemic fish occur at Edgbaston in the Barcaldine group (Fig. 3.3), the most ecologically diverse Great Artesian Basin spring complex in Australia. The Edgbaston goby (Fig. 3.4) is a close relative of the Elizabeth Springs goby and three other Chlamydogobius species from South Australia and the Northern Territory. All are morphologically similar and their speciation is an artefact of their prolonged isolation and subsequent evolution. The second species, the red-finned blue-eye, is far more curious. It is the only Pseudomugilid fish known from inland Australia all other species in this family live in coastal-draining rivers in northern and eastern Australia and New Guinea. Discovered in 1990 by fish biogeographer and geneticist Peter Unmack, populations of the species had dwindled to occupy only four of the 40 habitable springs when the conservation not-for-profit organisation Bush Heritage Australia purchased the property in 2008. The red-finned blue-eye was identified by IUCN as among the world’s 100 most endangered species of any animal or plant group, and is threatened by gambusia, feral and domestic stock, and aquifer drawdown. Gambusia probably out-compete red-finned blue eye because the former give birth to live young, meaning new-born juveniles are comparatively large and self-sufficient. In contrast, red-finned blue-eye are egg-layers, and gambusia are known to predate the eggs of Fig. 3.3. Great Artesian Basin springs form isolated wetlands that provide habitat for the endangered red-finned blue-eye and Edgbaston goby. These species are significantly affected by competition with the invasive mosquito fish. Trampling by livestock and feral animals and drawdown from water extraction are more general threats to spring complexes (photo, A. Kerezsy).
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