Southwest Australia Rivers and Streams

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Coastal granite, Cape Legrand, West Australia.
© WWF / Frédy MERCAY

About the Area

After Antarctica, Australia has the fewest rivers and the least run-off of any continent. There are several rivers in this ecoregion: the Swan, Murray, Blackwood, Warren, and Frankland, as well as many inland lakes. Some of the lakes and rivers in this ecoregion are dry for part of the year.

Comprised of short coastal rivers, this region exhibits lower species richness than Eastern Australia, but displays high levels of endemism due to long periods of isolation.

The pools and marshes that form among granite outcrops come and go with the seasons and support unusual species of plants and insects that have adapted to the changing availability of water.
Size:
325,000 sq. km (125,000 sq. miles)

Habitat type:
Small Rivers

Geographic Location:
Southwestern Australia

Conservation Status:
Critical/Endangered
Local Species
Nine of 14 fish species found in this ecoregion are endemic, as are 12 of 19 fairy shrimp (Anostraca) species.

Among the endemics are Freshwater cobbler (Tandanus bostocki), Nightfish (Bostockia porosa), Western pygmy perch (Edelia vittata), Long-headed goby (Afurcagobius suppositus), and King River perchlet (Nannatherina balstoni).

In addition, the anadromous and monotypic-pouched lamprey (Geotria australis) inhabits this ecoregion. Salamanderfish (Lepidogalaxias salamandroides) - the only species in the family Lepidogalaxiidae, is one of the distinctive species found here.

The salamanderfish may be related to galaxiids, of which there are 3 endemic species in this ecoregion as well: Western minnow (Galaxia occidentalis), Black-stripe minnow (Galaxiella nigrostriata), and Western mud minnow (G. munda).

Featured species

Salamanderfish (Lepidogalaxias salamandroides)

The Salamanderfish is an elongate species with a cylindrical body and reddish eyes. It is greenish-brown above and pale below. It has dark blotches and silver speckles on the sides of the body. It grows to about 7 cm in length. Males are smaller than females.

This species is found in freshwater streams and pools in sandy peat flat areas. When pools start to dry up in summer, the fish constructs a small burrow in which it aestivates until heavy rains fall in winter. The diet of salamanderfish consists mainly of insect larvae.

The Salamanderfish cannot move its eyes. Instead it has an unusually flexible neck, that allows the head to be moved independently of the body.

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Threats
A number of introduced species, including Rainbow trout (Onchorhynchus mykiss) and Brown trout (Salmo trutta) have proliferated in streams and rivers of the region. With the exception of one endemic species, all of the exotic species far outsize the native freshwater fauna found here.

Habitat loss (particularly of important ephemeral pools), alteration of the natural flow regime, and negative impacts from agricultural practices, all pose threats to the native biota.
WWF’s work

WWF launches bold new action plan for the west of Australia
16 Apr 2002
Perth, Australia - The Hon Judy Edwards, Western Australia's Minister for Environment and Heritage will launch WWF-Australia's new Western Region programme on 17 April.

The newly developed programme will include: extending WWF’s work to protect and recover threatened species and woodlands in southwest Western Australia; significant marine conservation initiatives; community action to protect shorebird sites; influencing state and regional water management policies; and promoting the conservation of rivers and wetlands in the Kimberley.

The Western Region program will continue to promote community action for threatened species conservation in priority ecoregions of Western Australia as well as with traditional landowners and pastoral communities in the central deserts.

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Photos and graphics © WWF or used with permission. Text available under a Creative Commons licence.