The total loss of saltmarshes in Australia is highly significant as habitat although it has not been great in area, with most loss concentrated in the south-east where the initial area was small. Coral reefs are among the most productive, diverse and complex ecosystems in the world. They are also under global threat. It is estimated that around 70 per cent of all the world's coral reefs are degraded in some way. This decline in the world's coral reefs has made the conservation of Australia's reefs of growing importance.
Coral reefs are well represented in marine protected areas.
Although most reefs are still in a relatively good condition, recent comparisons of several sites in the GBR show major changes have occurred to some of the reef flats over the last 40 to 100 years. The impact of human activity on the GBR requires further research and study. Australia has a unique, though poorly understood, area of submerged rocky reefs in temperate zones. These are well known for their commercial and recreational value, for fishing and diving, but there is inadequate scientific data on these areas and few are protected. Temperate reefs along Australia's southern coastline have a very high species diversity of algae and invertebrates and 80 per cent to 90 per cent of species are endemic.