Biodiversity publications archive

Refugia for biological diversity in arid and semi-arid Australia

Biodiversity Series, Paper No. 4
S.R. Morton, J. Short and R.D. Barker, with an Appendix by G.F. Griffin and G. Pearce
Biodiversity Unit
Department of the Environment, Sport and Territories, 1995

5. Foci of biological diversity in South Australia (continued)

5.2. Stony Plains

Area

181,951 km².

Primary land-use

Extensive pastoralism, mining.

National Parks and Nature Reserves

Witjira National Park.

Management problems

Land degradation due to over-grazing by stock and rabbits (Wilcox and Cunningham 1994). Birds of the chenopod shrublands appear to be particularly at risk of decline due to these effects (Reid and Fleming 1992).

The mound springs that characterise the Region suffer from problems of water drawdown, grazing and trampling by stock, and, more recently, pressure from campers and off-road vehicles (Lothian and Williams 1988). The discharge rate from springs is affected by an estimated 3-4,000 bores drawing from the Great Artesian Basin; it may also be affected by withdrawal of water for mines at Olympic Dam (Social and Ecological Assessment 1985). Extraction of groundwater from artesian bores has led to a fall in potentiometric surface to well below ground level and in turn to the decline and extinction of many mound springs. The Dalhousie complex discharges 41% of all mound spring discharge (1500 L/s) from Great Artesian Basin (Harris in Zeidler and Ponder 1989). Some authors believe that a new steady-state has been reached for the Great Artesian Basin in the last decade (Habermehl 1980 cited in Harris), but there has been a 6% decline in flow from the Dalhousie complex over the same period.

The introduced date palm Phoenix dactylifera is a management problem due to its abundance at some springs (Harris in Zeidler and Ponder 1989). Brumbies, feral donkeys, camels, rabbits and house mice are present around Dalhousie. The possible introduction of Gambusia affinis to mound springs could cause extinctions among aquatic organisms. A program of fencing to exclude stock is underway for 11 springs.

ANZECC-listed species

Mammals: Black-footed rock wallabies Petrogale lateralis (V) are known from the Davenport Ranges east of Coober Pedy (Eldridge et al. 1994a). The plains rat Pseudomys australis (V) is now confined to the lower Finke and Oodnadatta area (Breed and Head 1991). The kowari Dasyuroides byrnei (E) is recorded from the Region (Aslin 1983) but its current status there is uncertain.

Reptiles: The pygopodid Ophidiocephalus taeniatus (V), which is markedly confined to watercourses lined with gidgee Acacia cambagei between Abminga and Coober Pedy (Ehmann 1992; Cogger et al. 1993,
pp. 63-5).

Plants: Eriocaulon carsonii (Leigh et al. 1984, p. 103; Harris 1992), Atriplex kochiana (Leigh et al. 1984, p. 182), and Frankenia plicata (Leigh et al. 1984,
pp. 222-3), all (E) .

Species that are regionally endemic

The chestnut-breasted whiteface Aphelocephala pectoralis is unusual among birds in being endemic to one Region, the Stony Plains. The agamid lizard Ctenophorus gibba is endemic to gibber plains of the Region (Cogger 1992).

Among invertebrates of the mound springs, the endemic fauna is dominated by crustaceans and hydrobiid molluscs (Harris 1992). Endemics include the isopod Phreatomerus latipes, the ostracod Ngarawa dirga, further undescribed ostracods, a phreatic amphipod Phreatochiltonia anophthalma, further species of the amphipod genus Austrochiltonia, possibly endemic copepods, and a macrostomid flatworm. More than 20 taxa of snails (Hydrobiidae) have recently been found in artesian springs associated with the Great Artesian Basin in South Australia and parts of Queensland (Ponder 1986). Ten taxa are recognised in two endemic genera – Fonscochlea and Trochidrobia – from springs between Marree and Oodnadatta (Ponder et al. 1989); also, several species occur in artesian springs in Queensland (Ponder and Clark 1990).

The fishes include six species, of which four – Chlamydogobius sp., Neosilurus sp. and Craterocephalus dalhousiensis and C. gloveri – are endemic to the Dalhousie basin (Glover in Zeidler and Ponder 1989; Kodric-Brown and Brown 1993). Among 100 plant species recorded at Dalhousie, one is endemic to the springs complex (Nicotiana burbidgeae), one is the only record for central Australia (Lemna disperma), three constitute the only records for northern South Australia (Baumea arthrophylla, Hydrocotyle verticillata and Polygonum salicifolia) (Mollemans in Zeidler and Ponder 1989), and five are uncommon species in South Australia (Symon 1984 cited in Zeidler and Ponder 1989).

Relict populations

Mound springs stretch in an arc from Marree to north of Oodnadatta, at the fringe of the Great Artesian Basin (Lothian and Williams 1988). Twenty-two mound spring complexes exist, consisting of several hundred individual springs (Social and Ecological Assessment 1985). Mound springs are distinct mounds produced by minerals (soluble salts including sulphates, bicarbonates, chlorides and sodium, and in some cases accretions of Lower Cretaceous sands and clays) precipitated from the outflow of artesian waters. Active springs are generally <6 m in height, and provide a unique permanent wetland habitat in an arid environment. Dalhousie Springs consist of approximately 100 springs, of which 80 are active, and cover an area of 70 km² (Zeidler and Ponder 1989). There are large pools (largest 50 m long and 10 m deep); long drainage channels become extensive swamplands which support lush vegetation. Mollenmans (in Zeidler and Ponder 1989) estimated an area of 20 km² of wetland vegetation; on active mounds there is fringing vegetation of Melaleuca glomerata, Myoporum acuminatum, Typha domingensis, Phragmites australis and Cyperus gymnocaulos, and on drier slopes Acacia salicina. Lange and Fatchen (1990) noted that great variation exists in vegetation between springs. Further investigation is likely to reveal more relict species.

Other significant populations

An apparently isolated population of the fierce snake Oxyuranus microlepidotus occurs near Coober Pedy, SA (Read 1994).

Leigh et al. (1984) reported the rare plants Hemichroa mesembryanthema (p. 142) and Frankenia granulata (p. 222).

Wetland sites

The mound springs have been described above. In addition, Morelli and Drewien (1993) listed Lake Phillipson, south-west of Coober Pedy. The Lake is the terminus of the Long and Mabel Creek drainages, and is a freshwater ephemeral lake supporting large numbers of waterbirds, including freckled ducks Stictonetta naevosa.

Refugia

Dalhousie Springs (see section 11.1), the Lake Eyre mound springs (11.2), and Lake Phillipson (11.4) appear to represent refugia.