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The natural vegetation of Homebush Bay - Two hundred years of changes
... There is limited information about the distribution of saltmarsh species within individual NSW estuaries. In the Sydney region Clarke & Hannon (1967, 1969, 1970, 1971 identified seven species in a very detailed study at Towra Point, Clarke & Benson (1987) found the same seven species along the Lane Cove River, Clarke & Benson (1988) listed 25 species at Homebush Bay, and Pickthall et al. (2004) found 30 species along the Georges River. For Lake Illawarra, Yassini (985) listed 40 species, and for Jervis Bay Clarke (1993) listed 24 species. ...
... Flora surveys of Homebush Bay in Parramatta River (Clarke & Benson 1988;Adam 1996) have identified other species of conservation significance. Lampranthus tegens, a spreading, prostrate shrub is only found around the ports of NSW, appears to have been introduced from South Africa in the 19 th Century, but has since become extinct in that country (S.W.J. Jacobs, pers. ...
... Kelleway et al. (2007) did not find it in Lane Cove River, but located it at 89 other locations in the upper river and along the southern shore including Homebush Bay. Juncus acutus was recorded at the latter location some decades ago (Clarke and Benson 1988). This weed should be contained, and future management should also deal with continued disturbances caused by unauthorised access and recreational use of saltmarsh. ...
... The presence of the Navy, while it protected the area from many impacts of the later urbanisation of Sydney, led to further trenching, waste dumping and associated disturbances by the Navy itself. Nevertheless, the plant community appears to be a remnant of the original vegetation (Clarke and Benson, 1988). The second area of saline wetlands is represented by remnant patches of what was once a continuous border along the tidal length of Haslams Creek (Fig. 1). ...
... Lampranthus tegens was ®rst described botanically in Australia, from material collected near Homebush Bay (Robinson et al., 1983), but since the family Aizoaceae is not otherwise present in the continent's indigenous ¯ora, it is thought to have been introduced from South Africa. However, no exact equivalent can be found on that continent today (Adam, 1996), and according to Clarke and Benson (1988), the species is now endemic to a tiny area of the Port Jackson estuary, primarily in the Parramatta River basin. Halosarcia pergranulata is common on the saltpans on the western plains of this State, and is known in coastal areas in southern states. ...
The Homebush Bay area, Sydney, site of the Olympic Games 2000, has been largely occupied for nearly a century by an abattoir, brickworks, armaments depot and waste dumps. However, it contains remnants of original ecosystems, including two estuarine wetlands, and the Olympic Co-ordination Authority (OCA), set up to manage the redevelopment of the site, is committed to the rehabilitation of these ecosystems. The ecological approaches and rehabilitation measures used for one of the wetlands are detailed. Apart from a history of disturbance, it has for 10 years been without tidal flushing. However, these wetlands are the largest remaining in the Sydney estuary, and are significant for a number of reasons including biodiversity and waterbird conservation. The ecological parameters of the site, the results of a `before-restoration-impact' study, and the iterative links between science and management in the introduction of the rehabilitation measures, are presented. Criteria for success are discussed, along with biomonitoring strategies to test success.
... Mai Po Marshes (Lai and Lorne, 2006;Lai et al., 2006a) and Sydney's Homebush Olympic site (Burchett et al., 1999;Clarke and Benson, 2010;Saintilan and Williams, 2010) are good examples of the former. Efforts to restore the lower reaches of the Rhine in the Scheldt Estuary (Nienhuis et al., 2002;Van den Bergh et al., 2005) are good examples of the latter. ...
Informed by property rights economics, this paper explores some unique advantages of reclamation, as a form of expansionist dynamic zoning, compared to densification of existing built up urban land and conversion of rural and peri-urban land. One major argument is that modern reclamation package, in light of global circulation of capital, can be one comprehensive project that avoids old mistakes and tries out new ideas without upsetting pre-existing development or interests. It then explains, with the help of statistics collected from a historical study of land reclamation of Hong Kong, that the future urban development in this open economy will be arrested if she gives up reclamation. The loss of corporate memory, using civil service staff movements based on the Staff List, seldom used in Hong Kong studies on town planning, as a proxy, in strategic planning is advanced as a factor behind the current situation.
This paper presents the methodology and rationale used when differentiating fill and natural soft clays in a site on waterfront reclaimed land. The area of reclaimed land has a history of settlement impacting existing developments, which has motivated careful consideration of the ground conditions for future works. As the reclaimed land was dredged locally then loaded by fill and warehouses, it closely resembles the underlying estuarine and marine sediment lithology and consistency. Two historical ground investigations and one Arup ground investigation have been conducted, including clusters boreholes, cone penetrometer tests, seismic dilatometer tests and lab testing. The four types of subsurface information were compared to build and verify a ground model with an emphasis on the extent of reclaimed land. Peripheral desktop study information including historical maps, imagery, sea level records, and the historical settlements observed at site were considered to assist in differentiating the fill and natural soft clays. The importance of understanding this site’s history reinforces the value of a thorough desktop study when developing geological models.KeywordsSoft claysSettlementDesktop studyGround modelSite investigationReclaimed land
Careel Bay is the most significant area of estuarine wetlands in the Pittwater Local Government Area. Management of the wetlands is the responsibility of Pittwater Council. We have been engaged by Council to undertake a study of the birds of Careel Bay, their habitats and conservation needs, to guide Council in the preparation of a plan of management for the wetlands.
The bird habitats of Careel Bay and its immediate catchment may be divided into eight categories: subtidal waters of the bay (including an extensive area with submerged Posidonia australis seagrass beds); intertidal mudflats (including Zostera capricorni seagrass beds that are exposed at low tide); mangrove forest (10 ha, dominated by Grey Mangrove Avicennia marina); saltmarsh (3 ha, consisting of low, sparse mangroves over a ground layer of Samphire Sarcocornia quinqueflora); casuarina forest (4 ha, dominated by Swamp Oak Casuarina glauca, with a weedy understorey); eucalypt forest (McKay Reserve, Stapleton Park and Careel Headland Reserve); open parkland (Hitchcock Park); and residential areas (notable for their high tree density).
A total of 122 bird species (114 native) have been recorded from the area, of which 72 species (65 native) were recorded during the 1997 survey. lt is a regionally significant site for an endangered species, the Bush Stone-curlew Burhinus grallarius. Careel Bay, which has a single resident pair, is the only site in the County of Cumberland where this species is still regularly recorded. Also regionally significant is the Mangrove Gerygone Gerygone levigaster, a recent colonist of the Sydney region which is only known from two other sites in the County. Three other resident species are also noteworthy occurrences, particularly at the local level, the Striated Heron Butorides striatus, Whistling Kite Hatiastur sphenurus and Azure Kingfisher Alcedo azurea.
As the largest area of estuarine wetlands in Pittwater, Careel Bay provides habitat of high local conservation significance for a variety of waterbirds. These include migratory waders from the Northern Hemisphere such as the Eastern Curlew Numenius madagascariensis, Whimbrel N. phaeopus and Bar-tailed Godwit Limosa lapponica, whose conservation is the subject of international agreements. Careel Bay also has local significance as a temporary stopover for birds during migration, both waterbirds and bushbirds.
Management issues identified in the study were:
o Potential predation of Bush Stone-curlews by foxes and cats.
o Excessive disturbance by people and dogs of waterbirds feeding on the intertidal mudflats or roosting on the sandspit north of Etival Street.
o lnterference by increasing numbers of Silver Gulls Larus novaehollandiae in the feeding activities of other waterbirds on the mudflats.
o lnterbreeding of introduced Mallards Anas platyrhynchos with native Pacific Black Ducks A. superciliosa.
o Continued invasion of saltmarsh by mangroves resulting in the total loss of saltmarsh, a critical roosting and nesting habitat for the Bush Stone-curlew.
o Potential effects of various human-related factors on invertebrate and fish populations that are the food resources for the waterbirds.
Management recommendations are made to address these issues.
All records of crustaceans, molluscs, polychaetes, echinoderms and fishes from Sydney Harbour were extracted from the Australian Museum database, and plotted onto a map of Sydney Harbour that was divided into four regions. Records were analysed according to the number of species, genera and families present and over 3000 species were recorded, approximately double to triple the number of species found in the neighbouring Hawkesbury River, Botany Bay and Port Hacking. We examined the rate of accumulation of records and species over time since the 1860s, which followed a stepwise pattern usually correlated with the research activity of specific curators at the Australian Museum. The high species richness of Sydney Harbour is probably the result of multiple factors including significant tidal flushing and the high diversity of habitats present Not all parts of the harbour have been well sampled, however, and we highlight areas and habitats that should be prioritised for further biodiversity surveys. An Appendix is provided listing all species in the five groups of animals considered here. The present study highlights the remarkable richness of the Sydney Harbour fauna and provides a consolidated background to guide future management and research, and emphasises the values of museum collections.
The conditions that determine habitat suitability for waterbirds on temporary wetlands in Australia are poorly understood. This study describes the foraging behavior of the Black-fronted Plover (Elseyornis melanops) on two shallow saline lagoons with variable water depths. When water levels were receding, areas were left exposed around the periphery of the lagoons, which formed a succession from substrates still covered by water, to wet mud with a surface layer of water, to moist firm mud and eventually to dry, hard mud. The plovers showed a strong preference for feeding in areas of moist, firm mud and their prey capture rates were highest in this substrate type. When water levels rose following rainfall, previously exposed areas were partially flooded and the birds’ prey capture rates fell significantly. Most abandoned the lagoon. The species was thus highly dependent on receding water levels to provide suitable foraging conditions.
The landward transgression of man- groves into saltmarsh environments in the estuaries of south-east Australia over the last five decades is established as a widespread trend through a review of a number of independent studies. This process is occurring in a range of geomorphic settings, and in some cases reversing the direction of longer-term vegetation change. Several hypotheses are advanced to explain this occurrence, including increases in rainfall, revegetation of areas cleared for agriculture, altered tidal regimes or estuary water levels, and increases in nutrient levels and sedimentation.
It is clear that saltmarshes are a unique and important component of the coastal biosphere of Australia. Their contribution
ranges from stabilisation of fine sediments and providing an excellent protective buffer between land and sea, to their diverse
blend of terrestrial and marine fauna. Further, saltmarsh plants are highly specialised and adapted to fill a harsh niche
allowing them to act in roles that other vegetation types cannot. Saltmarsh habitats are recognised for their importance to
migratory waders under the Ramsar convention, but it is becoming increasingly evident that they are also important to a variety
of commercially valuable fish and native mammal species. Activities that are detrimental to saltmarshes continue and need
to be addressed in order to conserve remaining saltmarsh areas. In general, urbanisation of the catchment has lead to filling
of saltmarshes, tidal restriction, use by recreational vehicles, grazing, trampling and increased sedimentation and nutrient
runnoff allowing colonisation and invasion of mangroves. These disturbances have a number of ecological consequences ranging
from weed infestation to complete changes in the species composition and ecology. Reversing the disturbance is not always
simple and can require extensive groundwork to be successful. Rehabilitation of existing saltmarsh areas has been a successful
means to enhance this habitat. In general, it requires relatively little effort to remove weeds and fence off areas to regenerate
naturally. Saltmarsh areas have been shown to respond well to this type of manipulation. Restoration and creation require
substantial effort and planning to ensure a successful outcome. However, given the right environmental combinations of elevation,
tide and salinity, saltmarsh will establish and grow. To speed the process transplantation of saltmarsh plants can be considered
either from donor sites or plants propagated in green houses.
ResearchGate has not been able to resolve any references for this publication.