Australia has been isolated from the rest of the world for 50 million years. This has provided the flora and fauna a chance to evolve in unique ways, and therefore developing a high degree of endemism. Unlike North America, Australia has been tectonically very stable for a considerable period of time; no major mountain building has occurred for tens of millions of years. Parts of the Finke River are thought to have followed the same course for at least 65 million years (my) and possibly up to 350 my (Cook 1968 cited in Pickup et. al. 1988). Significant streamflow in parts of Central Australia ceased around 15my ago (Van De Graaff et. al. 1977), marking the time that aridity first began in Central Australia.

Today, 70% of Australia is semi arid to arid desert. In Central Australia, average daily summer temperatures are typically 37-39°C (98-102°F). Occasionally, they may climb into the low 50's (120's). Average daily winter temperatures range between 16-24oC (61-77°F). Night time temperatures in winter rarely drop below -2 or 3°C (28-26°F). In Central Australia, annual evaporation varies between 2400-4400mm (100-180 inches). Average annual rainfall varies between 110mm (4.4 inches) around Lake Eyre to 300-450mm (12-18 inches) on the margins. Rainfall is very sporadic. Droughts are the normal situation in Central Australia. However, localised falls can be extremely heavy, for instance, 300mm (12 inches) in an overnight storm at Merty Merty homestead (near Innamincka) (Bonython 1989).

Not surprisingly, the desert region of Australia supports a limited, highly localised fish fauna. Only thirty-three native species, and two subspecies from eleven families are present. The fish show a high degree of endemism and extraordinary adaptations for desert existence. Five exotic species have been recorded, however only three remain. Three native species have been translocated into Central Australian waters.

References

Bonython, C. W. 1989. Introduction and overview. In, The Great Filling of Lake Eyre in 1974. Eds. Bonython, C. W. & Fraser, A. S. Royal Geographical Society of Australasia, South Australian Branch, Adelaide. pp 1-9.

Pickup, G., Allen, G. & Baker, V. R. 1988. History, paleaeochannels and palaeofloods of the Finke River, Central Australia. In, Fluvial Geomorphology of Australia. Ed. Warner, R. F. Academic Press, Sydney. pp 177-200.

Van De Graaff, W. J. E., Crowe, R. W. A., Bunting, J. A. & Jackson, J. 1977 Relict early Cainzoic drainage's in arid Western Australia. Zeitschrift fur Geomorphologie. 21(4): 379-400.

This file was last modified:  18 March 2003