The different climatic zones of northern Australia produce a diverse array of wetlands that differ greatly in their hydrology and hence the behaviour of the animals and plants that depend upon them.
In the wet-dry tropic zone of the northern coastline the highly seasonal rainfall results in many of the freshwater wetlands drying out for varying periods during the long dry season. Here the remaining permanent waters (creeks, billabongs, swamps) become important refuge areas for many animals. This process can result in spectacular aggregations of wildlife that are a wonderful sight for tourists and provide a time of good hunting for the many traditional Aboriginal owners of the country.
In the Wet tropics of the east coast of north Queensland, although there is usually more rain in the summer monsoon period, there are many more permanent wetlands whilst in the arid regions of more southern parts of WA, NT and western Queensland wetlands may remain dry for years at a time.
A major feature of the coastal zone of northern Australia is the vast area of floodplain wetlands (marshes and Melaleuca swamps) that are, by comparison to southern Australia, largely unaffected by agriculture and industrial pursuits of modern society. The importance of many of these sites and other types of wetland, 106 in all, is recognised by their listing in the Directory of Important Wetlands in Australia. However, only 9 sites are listed as Ramsar sites of international importance compared to 44 sites in southern Australia. A number of sites (Arafura swamp; Gulf Salt flats) have also been proposed for registration on the National Estate.
The wetlands of northern Australia are necessary for the maintenance of viable populations of many aquatic fauna species (fish, birds, reptiles) which play an important role in the nutrition and culture of Aboriginal peoples and sustain important commercial and recreational fisheries and tourism.