Mangrove Forest

Sydney Olympic Park supports approximately 60 hectares of Mangrove forest, primarily located within Badu Mangroves, Nuwi Wetland, Haslams Reach and Newington Nature Reserve wetland.

Mangroves are trees and shrubs forming forests on the intertidal mudflats along the shores of estuaries, typically growing between saltmarsh and seagrass beds.  The Mangrove forest of Sydney Olympic Park is predominantly Grey Mangrove Avicennia marina, with small pockets of both naturally occurring and planted River Mangrove Aegiceras corniculatum.

The majority of the forest is relatively young, developing within the last 40 to 50 years following land reclamation works and resultant changes to hydrology and sedimentation.

Conservation significance

Sydney Olympic Park supports the largest areas of Mangrove forest within the Parramatta River estuary. They form part of a rare example of complete estuarine zonation of mangroves, Coastal Saltmarsh, Swamp Oak Floodplain Forest, and Eucalypt forest.

Mangrove forests play an important role in estuarine and marine ecology, providing habitat for many fauna species. Each square kilometre of Mangrove forest contributes about 600 tonnes of plant material each year to the estuarine food chain. Mullet, prawns, molluscs and crabs eat Mangrove detritus broken down by bacteria and fungi. Mangrove forests are nursery grounds, feeding areas and shelter sites for fish such as the flat-tail mullet and silver biddy, and support many bird species. Mangrove forests are also often used by migratory shorebirds as roost sites, and sometimes as foraging sites.

In addition, Mangrove forests play an important role in the protection of shorelines from erosion caused by wave action; in the filtration of pollutants from run-off; in the reduction of waterway siltation; and as a visual screen along developed shorelines.

Management

The Park’s Mangrove forests are highly modified systems - there has been historic construction of seawalls and bunds, alteration to creeklines, and sediment deposition, and consequent significant change to the original vegetation. Many of these changes have promoted mangrove growth at the expense of other estuarine habitats. However, more recently dieback was occurring in areas with poor tidal exchange.

Since the 1990s, restoration works have been undertaken to conserve and enhance the Park’s estuarine ecosystems. Works have included construction of tidal flushing channels and weirs to restore tidal regimes, and land remediation to prevent chemical contaminants from leaching into wetlands and waterways.

These works have reversed dieback and improved the health of Mangrove forests and related systems, however they have also caused change in the balance between Mangrove, Saltmarsh, casuarina and mudflat habitats. As a result, ongoing management of Mangrove and casuarina colonisation is needed to conserve key saltmarsh and mudflat habitats.

Small numbers of River Mangroves have been propagated and planted in upstream sections of Powell’s Creek, and a boardwalk installed in the forest of Badu Mangroves to support educational and interpretive programs and passive recreation.

Various monitoring and research projects have been undertaken within the Park’s mangrove forests, aimed at improving understanding of the ecology of the forest community and guiding its management.
The Authority undertakes strategic mosquito management across many of the Park’s estuarine wetlands, by aerial and ground-based application of a biological larvicide.