Estuarine ecological communities of Sydney Olympic Park are:
Coastal Saltmarsh is an ‘endangered ecological community’ of the intertidal zone of estuaries and lagoons. Sydney Olympic Park supports 20 hectares of remnant and regenerating Coastal Saltmarsh, across the Parklands precincts of Newington Nature Reserve wetland, Badu Mangroves, Haslams Reach, Haslams Creek Flats, Nuwi Wetland, Newington Armory, Blaxland Common and Wilson Park.
The term ‘Coastal Saltmarsh’ refers to the integrated assemblage of succulents, sedges, grasses, fauna and other organisms that form the ecological community. Saltmarsh provides habitat and food for invertebrates such as crabs, insects including mosquitoes, molluscs and spiders, as well as for fish, birds and bats. It is a breeding and nursery ground for marine life, and filters nutrients that would otherwise enter estuarine waters. Saltmarsh at Sydney Olympic Park provides habitat for migratory shorebirds protected under international treaties, and for one of the two known remaining Sydney populations of the White-fronted Chat.
Plants of the Coastal Saltmarsh community at Sydney Olympic Park include:
Elevation and hydrology affects species composition at particular locations – Sarcocornia quinqueflora dominates at lower, and hence more frequently inundated levels, whereas Wilsonia backhousei and Juncus kraussii prefer less frequent inundation.
Coastal Saltmarsh communities are undergoing widespread global and local decline. Coastal Saltmarsh in NSW was listed as an ‘endangered ecological community’ under the NSW Threatened Species Conservation Act 1995. An endangered ecological community is one that is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival cease to operate. The Coastal Saltmarsh of Sydney Olympic Park contains Wilsonia backhousei, a saltmarsh plant that was listed as ‘vulnerable’ under the NSW Threatened Species Conservation Act 1995 in 2000. A vulnerable species is one that is considered likely to become endangered in NSW unless the circumstances and factors threatening its survival or evolutionary development cease to operate.
Large areas of Coastal Saltmarsh have been lost from Homebush Bay and elsewhere along the Parramatta River as a result of land reclamation and development. The community has regenerated to some extent at Sydney Olympic Park, which now supports the largest remaining Coastal Saltmarsh community on the Parramatta River, and the second largest within the Sydney Basin. The Coastal Saltmarsh community contains the largest Sydney population of Wilsonia backhousei, and two species of restricted distribution and local conservation significance – Halosarcia pergranulata and Lampranthus tegens. The latteris thought to have been introduced from South Africa, but has naturalised in Australia and is now only known from the Sydney region and the Victorian coast. It is regarded as part of the cultural heritage of Sydney Olympic Park.
The Coastal Saltmarsh at Sydney Olympic Park also forms part of a rare example of complete estuarine zonation of Mangrove forest, Coastal Saltmarsh, Casuarina forest and Eucalypt forest.
Coastal Saltmarsh generally, and Wilsonia backhousei in particular, were identified as being of conservation significance in the early stages of Sydney Olympic Park’s redevelopment, many years prior to the legal protection that came with their listing under threatened species legislation.
Remediation works in the 1990s included several major estuary restoration projects. Remnant Coastal Saltmarsh was conserved and a nursery established to provide local provenance seed and cuttings used in replanting programs. The concrete-lined channel of Haslams Creek was replaced with a new creek-bed and newly-built tidal mudflats were planted with Coastal Saltmarsh. Tidal flushing was restored to the wetlands of Newington Nature Reserve to improve the health of the wetland communities, and Coastal Saltmarsh was planted along a newly-built Fishway in Bicentennial Park.
Remnant and planted Coastal Saltmarsh has been under active management since the 1990s. Current management actions within Coastal Saltmarsh communities include:
Restoration of tidal flushing within Newington Nature Reserve has resulted in a significant expansion of the saltmarsh community across Main Lagoon, at the expense of tidal mudflats. SOPA is seeking to achieve a balance between these two habitats through adaptive management of weir settings.
Various monitoring and research projects have been undertaken in the Coastal Saltmarsh of Sydney Olympic Park, aimed at improving understanding of the ecology of the community and guiding its management. These include a SOPA-funded PhD study of the ecology of Wilsonia backhousei and Lampranthus tegens.
The Authority undertakes strategic mosquito management across many of the Park’s estuarine wetlands, by aerial and ground-based application of a biological larvicide.
The saltmarshes of Sydney Olympic Park can be seen at:
Help to protect and conserve the saltmarsh by staying on the paths and do not pick saltmarsh plants.
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.
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.
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.
Olympic Park supports approximately 5 hectares of Swamp Oak Floodplain Forest (SOFF), an endangered ecological community. Some stands of this community have established naturally within the Park. In other areas, stands of this community have developed from planted trees.
The largest stand of the community occurs within Newington Nature Reserve, to the south of Main Lagoon where it lies between the Coastal Saltmarsh and Sydney Turpentine Ironbark Forest communities, and has established since 1955. Small areas also occur in other parts of the Reserve, within Newington Armory, along Haslams Creek, and within Badu Mangroves.
Swamp Oak Floodplain Forest is an ‘ecological community’ – an integrated assemblage of trees, shrubs, herbs, grasses and fungi, mammals, birds, amphibians, invertebrates and micro-organisms.
The Swamp Oak Floodplain Forest community occurs on the coastal floodplains of NSW. It typically forms mosaics with other floodplain forest communities and wetlands, and often fringes treeless wetlands with semi-permanent standing water, such as Main Lagoon in Newington Nature Reserve. The most saline forms of Swamp Oak Floodplain Forest may adjoin or intergrade with Coastal Saltmarsh. The boundaries between these communities are dynamic and may shift in response to changes in hydrological regimes, fire regimes or land management practices.
Swamp Oak Floodplain Forest has a dense to sparse tree layer in which Casuarina glauca is the dominant species northwards from Bermagui. Other trees including Acmena smithii and Melaleuca spp. may be present as subordinate species, but are found most frequently in stands of the community northwards from Gosford. Tree diversity decreases with latitude. The understorey is characterised by frequent occurrences of vines, a sparse cover of shrubs, and a continuous groundcover of forbs, sedges, grasses and leaf litter. The composition of the ground stratum varies depending on levels of salinity in the groundwater.
At Sydney Olympic Park, the Swamp Oak Casuarina glauca is the only canopy species present; dominant understorey and groundcover species are Myoporum boninense and Cupaniopsis anacardioides, and Juncus kraussii, though generally these strata are poorly developed.
Faunal components of Swamp Oak Floodplain Forest are poorly documented but both vertebrate and invertebrate assemblages can be diverse. The community sometimes provides food resources for the Yellow-tailed Black Cockatoo Calyptorhyncus funereus and the threatened Glossy Black Cockatoo Calyptorhynchus lathami lathami (although the latter has not been recorded to date at Sydney Olympic Park). Several species of microchirpoteran bats have been recorded foraging and roosting within the forest at Sydney Olympic Park, particularly the Lesser Long-eared Bat Nyctophilus geoffroyii.
The community also provides habitat for adult mosquitoes, and mosquito breeding sites where poorly drained depressions occur at higher elevations.
Swamp Oak Floodplain Forest was listed as an ‘endangered ecological community’ under the NSW Threatened Species Conservation Act 1995, in 2004. An ‘endangered ecological community’ is one that is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival cease to operate.
Although Swamp Oak Floodplain Forest occurs on floodplains throughout coastal NSW, it has been extensively cleared and modified. The remaining area of this community is considered likely to represent much less than 30% of its original range. It was estimated in 1998 that only about 13% of this community remained on the Cumberland Plain of western Sydney.
The remaining stands of Swamp Oak Floodplain Forest are severely fragmented by past clearing. Small areas of Swamp Oak Floodplain Forest are contained within existing conservation reserves including Newington Nature Reserve, but these occurrences are unevenly distributed throughout the range of the community and are unlikely to represent its full diversity. Very few examples of SOFF remain unaffected by weeds.
The community at Sydney Olympic Park has few weeds, and forms part of a rare example of complete estuarine zonation of Eucalypt forest, Casuarina forest, Coastal Saltmarsh and mangroves.
Weed control using bush regeneration techniques has been practiced for the past several years, with the result that there is now a very low level of weed infestation. In 2005, mowing ceased within part of the Newington Armory buffer zone, to promote expansion of the community.
During 1999/2000, Casuarina glauca were planted within parts of what is now Newington Nature Reserve following wetland remediation works. There is no documentation of the provenance of the Casuarina glauca plantings within the Reserve, though some local seed was collected and propagated for use in the extensive planting programs underway across Sydney Olympic Park at that time.
The majority of the Park’s Swamp Oak Floodplain Forest is fenced within Newington Nature Reserve; public access to this area has been restricted since the community developed. Re-introduction of tidal flushing to the Newington Nature Reserve wetland in the late 1990s initially caused some die-back of canopy trees. Forest health has since improved, following adjustment of the hydrological regime.
Casuarina glauca has been widely used in landscape plantings across Sydney Olympic Park since the 1990s. Planted stands and individual trees of Casuarina glauca in terrestrial areas are not currently considered to comprise the Swamp Oak Floodplain Forest community. Some plantings in estuarine areas, including Newington Nature Reserve may develop into this community over time.
Casuarina glauca is a highly invasive species that spreads by suckering and seeding, and is actively controlled in many parts of the Park where it poses a threat to other native species and communities such as Coastal Saltmarsh and Green and golden Bell Frog habitat.
The Authority undertakes strategic mosquito management across many of the Park’s estuarine wetlands, by aerial and ground-based application of a biological larvicide.