The Eastern Australian Region: a Dynamic Tropical/Temperate Biotone

Abstract

Eastern Australia lies in an overlap of tropical Indo-Pacific and temperate bioregions because of the influence of the southward-flowing East Australian Current. It has a very high biodiversity, from tropical coral reef and seagrass in the north, to coastal lakes and kelp communities in the south. Offshore, Norfolk and Lord Howe Islands and Elizabeth and Middleton Reefs, are the highest latitude coral reefs in the world. The coastal region includes South-East Queensland and New South Wales (NSW) and supports almost half of Australia’s population. Catchments have been extensively cleared for agriculture and water quality in many rivers and estuaries is poor. There has been major loss of wetlands and acid soil runoff causes fish kills and diseases in estuaries. The coastline is exposed, and much has been mined for heavy minerals and is subject to erosion. Urbanization and industrialization, particularly in the Sydney area, has resulted in sewage and heavy metal pollution. Many of the coastal fisheries are declining, largely because of loss of water quality and wetlands habitats, and in some cases overfishing. Marine environmental management (the responsibility of the two states to the 3 mile limit, and the Commonwealth to the boundary of the 200 mile EEZ) is variable, and largely focused on the urban centres. Queensland has a system of marine protected areas (MPAs) while NSW has minimal protected areas. The major issues are declining water quality, loss of estuarine habitats, degradation of coastal lakes, and localized pollution from heavy metals and sewage in the Sydney area.