St Kilda mangroves
The Dry Creek salt field in the vicinity of the St Kilda mangroves is a complex 30 kilometre, 4000 hectare site which encompasses the Adelaide International Bird Sanctuary and the Adelaide Dolphin Sanctuary.
This area provides important feeding and roosting habitat for migratory and resident shorebirds, is recognised as a wetland of national significance and is part of the East Asian-Australasian Flyway Site.
It contains Temperate Saltmarsh, which is listed as a threatened ecological community under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The salt field areas to the south also form part of the Barker Inlet-St Kilda Aquatic Reserve.
The South Australian Government shares the community’s concern about the vegetation dieback at St Kilda in the vicinity of the Dry Creek salt field.
Scientific reports on vegetation dieback
The Department for Environment and Water (DEW) has developed a mapping methodology to measure the extent and composition of native vegetation impacted in the St Kilda dieback event of late 2020.
Approximately 9 hectares of mangrove; 10 hectares of saltmarsh; and nearly 5 hectares of bare, sparsely vegetated, or aquatic ecosystems within the Adelaide International Bird Sanctuary National Park – Winaityinaityi Pangkara (AIBS) at St Kilda have been impacted.
Mapping of the site was undertaken by DEW in March 2021, which determined there was no significant expansion of previous dieback areas, and no appearance of new dieback areas. There is high confidence that no major areas of dead vegetation occur outside this mapping. See the Vegetation dieback extent and composition map.
Mangrove propagule monitoring was undertaken between December 2021 and November 2022. It examined the rate of recovery following a hypersalinity event. The aim was to look at the natural recovery of the area and mangrove propagule dispersal through the forest and persistence of juveniles. The Persistence study: Propagules and juvenile mangroves at the St Kilda boardwalk will inform the feasibility of future restoration works through mangrove propagule translocation.
*NEW* University of Adelaide conceptual models of saltmarsh and mangrove vegetation
In 2022, DEW commissioned the University of Adelaide Acid Sulfate Soil Centre to develop conceptual models of the St Kilda site, impact pathways and a timeline of the 2020 event. The project also summarised relevant scientific knowledge of the hydrology and ecology of the site and to provides potential future management options for the impacted area. Relevant experts and stakeholders were consulted and available scientific data collated and summarised. See:
- Summary report: St Kilda Mangrove and Saltmarsh Hypersaline Brine Contamination 2020 (University of Adelaide, Dec 2022)
- Conceptual model: St Kilda mangrove and saltmarsh hypersaline brine contamination 2020 conceptual model (Intertidal Zone Adjacent Section 2).
Further information can be accessed in the scientific reports and online data viewer:
- The Dry Creek salt fields vegetation impact mapping Spring 2021 summary report provides an update to initial mapping base on September 2021 imagery.
- The Dry Creek salt fields vegetation impact mapping: Summary report summarises the results and insights from the integrated analysis.
The Dry Creek salt fields vegetation impact mapping: DEW Technical report presents the results and insights, describes methods used, and outlines next steps. It has been independently reviewed.
Online Data Viewer
DEW used a variety of mapping techniques and datasets to measure the extent of dieback. The Dry Creek salt fields Online Data Viewer lets users pan, zoom and compare the datasets compiled and used in the analyses.
Experts from the Department for Energy and Mining (DEM), DEW, the Environment Protection Authority (EPA) and the University of Adelaide, along with external consultants, are collaborating to:
- stop further impact
- promote conditions for recovery of the affected areas
- establish long-term environmental stability for the mangrove and wider ecosystem.
DEM is the lead regulator and regulates the salt fields site under the Mining Act 1971. The DEM website has up-to-date information on the current activities underway.