Threats to Australian desert springs


The following is an abbreviated summary of the extent of impacts largely drawn from summaries by Harris (1992) and Ponder (1986).

Aquifer drawdown

The water in the Great Artesian Basin (GAB) was first tapped in the late 1870's when the first bores or wells were sunk. This caused an initial period of drawdown or loss of pressure in the aquifer which resulted in a decline in spring discharge. This probably affected most springs within the GAB to some degree. Virtually all springs in the Bogan and Bourke supergroups are extinct or nearly so (Pickard 1992), many in the Eulo supergroup are extinct (Ponder 1986), and only 1 spring, Elizabeth Springs (which flows at <95% of its original rate) remains active in the Springvale supergroup (Habermehl 1982). Many of the Lake Eyre supergroup springs are also reduced in flow based on comparisons between descriptions by early explorers. Today, the GAB is in equilibrium between recharge and discharge; that is, no further decrease in spring flow is expected providing no new developments occur. In an effort to reduce the wastage of water, there is an active program underway to control or cap flowing bores. This should hopefully improve the situation somewhat and may actually enhance spring flows. One development that threatens the Lake Eyre supergroup is the Olympic Dam mining venture. Presently, the mine with draws 15 megalitres (4,000,000 gal) per day, however, it is planned to expand this to 33 megalitres (8,700,000 gal) per day (Harris 1992). Present levels of extraction has impacted several nearby springs, the impacts of increased extraction are difficult to accurately predict. Further, there is a proposal to establish an iron smelting plant near Coober Pedy. This will presumably use artesian water in considerable amounts, if not for industrial processes then certainly for the proposed township. There is also another mining proposal at Cloncurry (near Julia Creek, Queensland) that hopes to use GAB water (R. Wager pers. comm.).

Cattle grazing

Virtually every spring has cattle or sheep grazing on it except those at Dalhousie Springs where grazing ceased in 1985 (Harris 1989). A few of the Lake Eyre Springs were fenced in 1986-1988 (Harris 1992), and a few springs are protected within Carnarvon Gorge National Park (Ponder & Clark 1990). Due to the lack of water and fodder, stock tend to congregate around springs. This results in considerable trampling of the surrounding area as well as disturbance to the spring itself. Faeces tend to pollute springs by causing high ammonia concentrations. Occasionally, stock get trapped in soft mud and die, or they just happen to be in a spring when they die. In very small springs this results in the complete loss of fauna, in larger springs the total biomass tends to be reduced.

Spring alterations

Many springs in Queensland have been dug out by pastoralists to improve water supply for stock (Ponder & Clarke 1990; R. Wager pers. comm.). Why primarily in Queensland? This is probably because many of the springs there are fairly small and it has a higher density of people and pastoral properties (ranches). None of the springs have been channelised or diverted primarily because of their small size, no irrigation has occurred in Central Australia, and the springs were generally easily accessible to stock.

Introduced species

The only recorded introduced species is damnbusia, which occurs in a few springs in the Neales River and Frome Creek portions of the Lake Eyre supergroup, and a few scattered Queensland springs. They are gradually expanding their range primarily through flood dispersal. They are a major problem at Edgbaston Springs where they threaten redfinned blue eye and Edgbaston goby (Unmack & Brumley 1991; Wager & Unmack in prep.). No efforts have yet been made to eradicate damnbusia from any spring. Fortunately, due to its isolation, Dalhousie Springs remains free of exotic fish. However, this could easily change with increased tourist numbers, and the large warm pools (32-38C) (90-100F) may make ideal environments for some tropical fish species.

Fencing of springs

There is considerable debate as to whether fencing springs to prevent animal grazing is threatening or protecting them. The few Lake Eyre supergroup springs which have been fenced have become overgrown with Phragmites australis. This may result in a change to the plant and animal communities of unknown proportions. If the springs are not fenced, then they risk being destroyed by cattle trampling and pollution. There is also disagreement as to how much grazing occurred on the springs prior to European settlement. Did the spring flora and fauna ever experience grazing? Have the springs had time to come into equilibrium with cattle grazing? Have the springs changed to the point where they are dependent upon grazing to maintain aquatic habitats? For example, P. australis tends to decrease water depth by collecting sediment, but they were present before cattle grazing. Also, what was the water depth then? (Although the flow rate was higher then too). We also don't know how the Aborigines managed the springs. It is thought that they may have used fire to maintain access to the springs or to catch game, etc. Another historical question is, what where the springs like when the mega-fauna roamed around the springs before their extinction around 10,000 years ago? These are challenging management questions, which no one has attempted to answer yet.

References

Habermehl, M. A. 1982. Springs in the Great Artesian Basin, Australia - their origin and nature. Bureau of Mineral Resources, Geology & Geophysics, Australia Report No. 235.

Harris, C. 1989. Dalhousie Springs - An introduction. In, Natural History of Dalhousie Springs. Eds. Zeidler, W. & Ponder, W. F. South Australian Museum, Adelaide. pp 1-4.

Harris, C. 1992. Mound Springs: South Australian conservation initiatives. The Rangeland Journal. 14(2): 157-173.

Pickard, J. 1992. Artesian springs in the Western Division of New South Wales. The Graduate School of Environment Working Papers Series, Macquarie University. Paper No. 9202. pp 123.

Ponder, W. F. 1986. Mound springs of the Great Artesian Basin. In, Limnology of Australia. Eds. DeDeckker, P. & Williams, W. D. CSIRO, Australia and W. Junk, The Hague. pp 403-420.

Ponder, W. F. & Clark, G. A. 1990. A radiation of hydrobiid snails in threatened artesian springs in western Queensland. Records of the Australia Museum. 42(3): 301-363.

Unmack, P. & Brumley, C. 1991. Initial observations on the spawning and conservation status of the redfinned blue-eye, (Scaturiginichthys vermeilipinnis). Fishes of Sahul. 6(4): 282-284. (Journal of the Australian New Guinea Fishes Association, Australia).

Wager, R. N. E. & Unmack, P. J. (in prep) Threatened fishes of the world, Scaturiginichthys vermeilipinnis.


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This file was last modified:  18 March 2003