IUCN Red List of Ecosystems, Mangroves of the East Central and Southeast Australian Shelf

Tertius de Kluyver, Norman C. Duke, James E. Longworth, Patrick G. Dwyer, Neil Saintilan, Catherine E. Lovelock, Ena Suarez, Sean G. MCGregor

Mangroves of the East Central and Southeast Australian Shelf is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology). It includes the marine ecoregions of Bassian, Cape Howe, Lord Howe and Norfolk Islands, Manning-Hawkesbury, Tweed-Moreton, and Western Bassian. The East Central and Southeast Australian Shelf mangrove province mapped extent in 2020 was 462.2 km2, representing 0.3% of the global mangrove area.
The province has a warmer subtropical northern region but is largely temperate in climate that results in a gradient of decreasing mangrove diversity as latitude increases. There are 11 species of mangrove reported for this province, only 6 of which are still present at the border between Queensland and New South Wales. This is reduced to only one species in Victoria and South Australia. The province is also diverse in its geomorphology with its northern extent characterised by large coastal sand islands protecting estuaries then, moving south into New South Wales, broad river estuaries and drowned river valleys and bays, and into southern NSW and Victoria with their large coastal lakes and lagoons, large bays and finally the coastal cliffs and rocky inlets of western Victoria and SE South Australia. All but the last of which offer a variety of habitats in which mangroves are established.
Today the East Central and Southeast Australian Shelf mangroves cover +1.3% greater extent than our broad estimation for 1970. However, the mangrove net area change has been 0.1% since 1996. If this trend continues an overall change of 0.4% is projected over the next 50 years. However, under a high sea level rise scenario (IPCC RCP8.5) ≈-33.7% of the East Central and Southeast Australian Shelf mangroves would be submerged by 2060. Moreover, 0.7% of the province’s mangrove ecosystem is undergoing degradation, with the potential to increase to 2.1% within a 50-year period, based on a vegetation index decay analysis. Overall, the East Central and Southeast Australian Shelf mangrove ecosystem is assessed as Vulnerable (VU).