Saltmarsh research
From WetlandLink
The coastal saltmarshes of Victoria: extent, condition and threats
Paul I. Boon
Victoria University
Institute for Sustainability & Innovation
Contact: Paul Boon
Coastal saltmarshes are amongst the most abused of all of Victoria’s wetland ecosystems. Altered hydrological conditions, impacts from sea-level rise, clearing, reclamation for coastal development and weed invasion have led to significant declines in these wetlands for at least a century. Current trends suggest that saltmarshes will be almost fully lost within the next few decades, especially due to Climate Change, unless there is a concerted effort to address these issues.
Coastal saltmarsh and mangrove plant communities are scattered along Victoria’s coast, on sheltered (low-energy) flats, associated with bays, estuaries, barrier islands and spits. Coastal saltmarsh and mangrove environments support several distinctive plant communities/associations, forming herbfields, shrublands, sedgelands and/or grasslands. These are only partly described in the Department of Sustainability & Environment’s current EVC typology. These and adjacent environments also provide habitat for native fauna, (including endangered species such as the Orange-bellied Parrot), ecosystem services benefiting commercial and recreational fisheries, and are foci for recreation and coastal development.
The Victorian coast is one of the few places where saltmarsh and mangrove co-exist: mangroves are frost-limited further south and saltmarshes are reduced in extent and floristic diversity to the north. In a national and global context, Victorian saltmarshes are well developed and have high alpha and gamma diversity; over 120 vascular plant species have been recorded from these ecosystems across the State. Mangrove and saltmarsh communities are spatially restricted in Victoria, as they require sheltered, low energy coastlines. Although discrete patches of saltmarsh along the coast are typically less than 100 ha, larger continuous areas over 1000 ha occur in Westernport Bay, Corner Inlet and along the lower Barwon River. It is estimated that there is less than 12,000 ha of saltmarsh and mangrove vegetation remaining in Victoria. What proportion of the original extent of intertidal vegetation this represents is currently difficult to determine. It is clear, however, that extensive areas of saltmarsh have been lost as a consequence of the development of salt production facilities and the carrying out of so called ‘reclamation’ works such as coastal drainage schemes and seawall construction. Key areas of direct loss include the northern shoreline of Corner Inlet, the eastern shoreline of Westernport Bay and the western shoreline of Port Phillip Bay.
Professor Paul Boon, from the Institute for Sustainability & Innovation at Victoria University in Melbourne, leads an NHT-funded project to help address the decline in extent and condition of coastal saltmarshes. The project is a collaboration between Victoria University, Ecology Australia, Biosis Research, the Arthur Rylah Institute, Pathways Bushland & Environment, and Ipsos. Tim Allen, from the Department of Sustainability and Environment, is the project’s immediate link with government. The project will provide the first comprehensive State-wide assessment of Victoria’s coastal saltmarshes, assess the extent and condition of existing saltmarsh remnants, identify specific threats to the survival of these communities and, most importantly, provide clear strategic guidance to management authorities regarding required on-ground actions to halt the decline. It will assess also the current extent of the exotic weed Spartina in Victoria’s estuaries and embayments and facilitate the development of a coordinated action plan to control these infestations.
Figure 1: An example of Victorian coastal saltmarsh. Photograph by Tim Allen, Department of Sustainability and Environment.
See other Research on wetlands
