What is a mangrove forest?

A mangrove forest is a coastal forest of salt-tolerant trees and shrubs that grow in the intertidal zone where rivers meet the sea. Australia has the third-largest area of mangroves in the world after Indonesia and Brazil, covering about 11,500 square kilometres along an estimated 20,000 kilometres of coastline.

Mangroves grow in saltwater, with specialised roots that exclude or excrete salt and aerial roots that take in oxygen above the waterlogged mud. Australia is home to about 41 mangrove species, far more than the seven species found across Africa or the eight in the Americas. The richest mangrove forests are in tropical northern Australia, especially the Kimberley, the Top End (including the Kakadu and Cobourg coasts), the Gulf of Carpentaria, and Cape York Peninsula.

Mangroves provide critical nursery habitat for fish and crustaceans, with estimates that 75 per cent of Australia's commercially caught fish depend on mangrove ecosystems at some life stage. They also stabilise coastlines against erosion and storm surge, store extraordinary amounts of carbon in their soils (so-called blue carbon), and support iconic species such as saltwater crocodiles, mudskippers, mangrove jacks, and several mangrove-specialised birds.

Australia experienced its worst-recorded mangrove die-off in 2015 to 2016, when about 40 million mangroves, covering 7,400 hectares of the southern Gulf of Carpentaria, died over a few months because of a combination of low sea levels, drought, and a marine heatwave linked to El Nino. Recovery has been partial. Mangrove conservation is now part of Australia's commitments to international blue-carbon initiatives, with several state programs rehabilitating cleared estuaries through replanting and removing barriers to tidal flow.