Central Australian Freshwater

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Kakadu National Park, Australia.
© WWF / Frédy MERCAY

About the Area

Characterised by some of the most unpredictable flow patterns of any continent, freshwater systems in arid Australia support species with amazing adaptations to environmental variability. This ecoregion has high levels of local endemism with many species that have survived here for millions of years.

This ecoregion is defined primarily by the interior-draining Lake Eyre and Bulloo-Bancannia drainage basins, though it also overlays a portion of the Great Artesian Basin, one of the world's largest artesian (underground) basins. It covers 1,760,000km² (633,600mi²) or 22% of Australia.

Around the artesian basin occur numerous mound springs and spring-fed complexes, such as Dalhousie Springs. These springs, some of which are as warm as 46°C, can be as old as a million years.
Size:
1,340,000 sq. km (517,000 sq. miles)

Habitat type:
Xeric Basins

Geographic Location:
Central Australia

Conservation Status:
Vulnerable

Local Species

Seen here are exceptional levels of endemism in fish, wetland-dependent plants, amphipods, ostracods, isopods, and snails (more than 20 species in at least 2 endemic genera). A large portion of this ecoregion's freshwater species exhibits highly restricted ranges, though a few such as Spanged perch (Leiopotherapon unicolor) are more widespread.

The Dalhousie Springs fauna is notable for its extremely high endemicity that includes species like the Dalhousie catfish (Neosilurus sp.), Dalhousie hardyhead (Craterocephalus dalhousiensis), Dalhousie mogurnda (Mogurnda sp.), and Dalhousie goby (Chlamydogobius gloveri).

Other endemics found at Dalhousie Springs are at least 6 snails, 1 blind crustacean, possibly 1 crayfish, and 1 frog species. Endemic plants to the mound springs in general include Halosarcia fontinalis and Eriocaulon carsonii.

Featured species

Dalhousie hardyhead (Craterocephalus dalhousiensis)

The largest recorded hardyhead is 78mm (3in) SL. They are commonly found up to 50mm (2in). They occur in the wild at temperatures from 20°C to 40°C (68 to 104°F) and make very brief excursions into water of 41.8°C (107°F). This is the highest recorded voluntary temperature tolerance of any Australian fish and one of the hottest voluntary temperatures that fish have been recorded at anywhere in the world!

They are generally found in the pools and channels in the spring outflows. The minimum dissolved oxygen tolerated is 0.5 mg O2/L. Their diet consists mostly of green filamentous algae but also includes ciliates, ostracods, insects, hydrobiid snails, detritus, and worms. They are morphologically sexually dimorphic. Virtually nothing is known of reproduction in the wild.

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Threats

In this arid ecoregion, any water withdrawals or other modifications to the flow regime pose serious threats to aquatic species. Illegal fishing, exotic species, overgrazing, and untreated sewage disposal threaten the fragile aquatic ecosystems. In addition, proposed dams, water diversions, and commercial fisheries pose a future threat.

WWF’s work

Working with World Expeditions and the World Wildlife Fund (WWF) with the "Escape to the Andes" program, Outdoor Australia has helped to raise $43,000 for the WWF Threatened Species Program. The money is used by WWF to care for the many creatures that are currently under threat in the Australian landscape. WWF Australia began its work, 25 years ago, focused on recovery of threatened plants and animals.

Over the years, WWF learnt that working to recover a single species is nowhere near as useful or effective as working on a landscape scale. This means developing multi-species recovery plans, protecting habitat, and fostering wiser management of our land and water resources. Today, WWF's Threatened Species Program encompasses all these activities and more.

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