Australia has approximately 11,500 km2 of mangroves, primarily on the northern and eastern coasts of the continent. Areas where mangroves occur include the intertidal zone of tropical, subtropical and protected temperate coastal rivers, estuaries, bays and marine shorelines
Australian mangrove forests comprise 41 plant species from 19 families, which is approximately half the world’s mangrove species.
Each mangrove tree species is specific to particular latitudes and levels of tidal inundation. The greatest diversity of species is found in the far northern and north-eastern areas of Australia, and declines rapidly with increasing latitude. For example, Darwin Harbour, in the north of Australia, contains 36 mangrove tree species, while Bunbury, in the south, contains only one mangrove tree species. There are no mangroves in Tasmania.
Mangrove forests also support several salt-tolerant plant species which are not classed as mangroves. In tropical areas, this may include the Mangrove Palm (Nypa fruticans), the Mangrove Fern (Acrostichum speciosum), and orchids which grow on the trunks and branches of mangrove trees. Other plants found in association with mangroves include the Mangrove Lily (Crinum pedunculatum).
Mangrove forests provide breeding nurseries for a wide range of fish and crustaceans, including many species of commercial and recreational value, for example, Barramundi (Lates calcarifer), Mangrove Jack (Lutjanus argentimaculatus), mud crabs (Scylla serrata) and Banana Prawn (Penaeus merguinensis). The forests also provide a habitat for spat settlement and development of oyster species.
Many terrestrial fauna, such as insects, reptiles, frogs, birds and mammals, use mangroves for food, shelter, breeding and feeding grounds.
The Rusty Monitor (Varanus semiremex) shelters in the hollows of mature or dead mangrove trees in north-eastern Queensland. The Mangrove Snake (Fordonia leucobalia) and Estuarine Crocodile (Crocodylus porosus) are found in mangrove forests in the north.
The Lesser Noddy (Anous tenuirostris melanops) builds a platform nest of leaves in mangrove trees. This bird is listed as Vulnerable under Australia’s Environment Protection and Biodiversity Conservation Act 1999.
Mangrove forests provide habitat for many small insectivorous birds, including the Varied Honeyeater, Mangrove Honeyeater, Rufous-banded Honeyeater, Mangrove Robin, Lemon-bellied Flycatcher, Buff-sided Robin, Little Shrike-thrush Grey Whistler, White-breasted Whistler, Northern Fantail, Mangrove Grey Fantail, Arafura Fantail, Broad-billed Flycatcher,Shining Flycatcher, Spectacled Monarch, White-eared Monarch and Yellow White-eye. Other bird species observed to frequent mangrove forests are the Rose-crowned Fruit-Dove, Little Bronze-Cuckoo, Papuan Frogmouth, Azure Kingfisher, Little Kingfisher, Forest Kingfisher, Collared Kingfisher, Sacred Kingfisher and Fawn-breasted Bowerbird.
Mangrove forests are sometimes used as nursery areas by flying foxes in the Darwin Harbour and other areas of Australia. Several species, including the Little Red Flying Fox, are dependent on mangrove pollen as food.
Mangroves protect coastal areas from erosion, storm surge, and tsunamis. The massive root systems of mangroves are efficient at dissipating wave energy. Mangroves retard the tidal movement of water, allowing sediment to be deposited as the tide comes in, and leaving all except fine particles when the tide ebbs. Mangroves therefore build their own environment.
The commercial and recreational fishing industries are prime beneficiaries of mangrove forests, which provide breeding and feeding grounds for fish and prawns. About 75% of the fish and prawns caught for commercial and recreational purposes in Queensland spend at least part of their lifecycles in mangroves.
In some coastal communities, boardwalks and bird-viewing areas in mangrove forests provide attractions for the eco-tourism industry, for example, at Boondall Wetlands