186 Endangered Freshwater Invertebrates Box Mound springs of the Great Artesian Basin in Australia Much of the arid interior of eastern Australia is underlain by a large aquifer called the Great Artesian Basin Fresh- or brackish-water springs occur along the margins of this aquifer in Queensland, New South Wales, and South Australia These springs range in size from small, moist seeps to large (4100 L sÀ1), flowing springs, and some of them have built up large (410 m high) hills of sand and mineral deposits, and so are locally called ‘‘mound springs.’’ Although perhaps connected to one another in the past, when the Australian climate was wetter, the springs are now separated from one another by a few meters to many kilometers of desert, and are not connected by streams or rivers Like many springs in arid regions, the springs of the Great Artesian Basin support animals that live nowhere else in the world (Ponder, 1986, 1995; Ponder et al., 1989; Ponder and Clark, 1990; Knott and Jasinka, 1998; Perez et al., 2005) Many of these species are found in only one or a few neighboring springs Only the fish and the snails of these Australian springs have received much study About 25 species and three genera of snails have so far been found to be endemic to the springs (Figure 9) All of the endemic snails belong to the Hydrobiidae, a widespread family that has produced flocks of endemic species in springs, caves, and ground waters in the Balkans, the arid Southwest of the United States and Mexico, and elsewhere Although these snails may be very abundant in the Australian springs (41,000,000 mÀ2), some species are restricted to one or a few springs, and all are highly vulnerable to human impacts The endemic fauna is thought to have originated by speciation in the more or less isolated springs, perhaps after a more widespread fauna was stranded in the springs by an increasingly arid Australian climate in the Pleistocene The chief threat to the spring fauna is from development of wells in the Great Artesian Basin Because this is an arid region, there is great demand for water for humans, livestock, and mining When new wells are brought into production, the groundwater level drops, causing springs to dry up Additional threats include trampling of springs by livestock, which has badly degraded many springs, conversion of springs into pools by excavation or damming, and introduction of non–native species Over the past three decades, the springs of the Great Artesian Basin have come to be recognized as important habitats for conservation, and steps are being taken to limit at least local impacts from grazing and habitat alterations Nevertheless, many springs, especially in New South Wales, have dried up as a result of groundwater extraction, and many have been badly altered by livestock or people It seems likely that at least some of the unique invertebrates of the Great Artesian Basin have gone extinct, and the remaining fauna are at risk of loss In arid regions around the world, extreme isolation of aquatic habitats has promoted speciation and development of endemic invertebrate faunas As in the Great Artesian Basin, water in arid regions is a critically important resource that has been exploited heavily by people Consequently, freshwater invertebrates of arid regions around the world are endangered by forces similar to those at work in the Great Artesian Basin References Knott B and Jasinska EJ (1998) Mound springs of Australia In: Botosaneanu L (ed.) Studies in Crenobiology: The Biology of Springs and Springbrooks, pp 23–38 Leiden: Backhuys Perez KE, Ponder WF, Colgan DJ, Clark SA, and Lydeard C (2005) Molecular phylogeny and biogeography of spring-associated hydrobiid snails of the Great Artesian Basin, Australia Molecular Phylogenetics and Evolution 34: 545–556 Ponder WF (1986) Mound springs of the Great Artesian Basin In: De Deckker P and Williams WD (eds.) Limnology in Australia, pp 403–420 Melbourne: CSIRO Ponder WF (1995) Mound spring snails of the Australian Great Artesian Basin In: Kay EA (ed.) The Conservation Biology of Molluscs., Occasional Paper of the IUCN Species Survival Commission 9, pp 13–18 Gland: IUCN Ponder WF and Clark GA (1990) A radiation of hydrobiid snails in threatened artesian springs in western Queensland Records of the Australian Museum 42: 301–363 Ponder WF, Herschler R, and Jenkins B (1989) An endemic radiation of hydrobiid snails from artesian springs in northern South Australia: Their taxonomy, physiology, distribution and anatomy Malacologia 31: 1–140 occur in hot spots, so species-based research and protection will necessarily have to accompany any program of hot-spot protection Further, we could be more aggressive about identifying and removing threats that endanger species rather than just trying to protect the few populations that have somehow escaped threats This will require creative thinking about how to preserve or restore essential features of habitat without making unrealistic demands on humans A second class of possible solutions could be focused on alleviating the dispersal limitations that are so acute for many freshwater invertebrates by actively establishing new populations of endangered species This class of solutions is motivated by two main concerns First, simple protection of existing populations of endangered species may fail to assure long-term survival because natural or human-caused catastrophes (e.g., chemical spills) or normal population fluctuations ultimately may take many isolated populations into extinction Second, it seems likely that global climate change may be faster than the abilities of some freshwater invertebrates to disperse into suitable habitats To preserve species under these conditions it may be necessary to deliberately establish populations of endangered species in new locations where suitable habitat exists This strategy, which is called ‘‘assisted migration,’’ has received a lot of attention from conservationists in recent years However, this strategy has serious problems when applied to freshwater invertebrates because we know so little about these animals (the typical species of endangered freshwater invertebrate in the United States has been mentioned in a total of just one scientific publication!) First, we currently cannot reliably identify ‘‘suitable habitat’’ for most freshwater invertebrates Second, we not have good protocols for reintroductions for most species Third, species introduced outside their native ranges may have unpredictable and undesirable effects on ecosystems and species Finally, many biologists feel that it is unethical to introduce species outside of their known historical ranges (of course, for many invertebrate species, the known historical range is much smaller than the actual and unknowable historical range) Despite these problems, it may be necessary to confront the problem of species reestablishments, especially if climate change in the twenty-first century is substantial Clearly, we will need much better information on how fast species are able to disperse in response to a changing climate (to identify which species, if any, will perish without intervention), practical information on how to establish populations of freshwater