Saltmarsh occurs in areas that are periodically inundated by the sea, where the wave action is subdued and sediments are able to accumulate. It is therefore largely confined to estuaries and inlets. Near the mouths of estuaries and inlets, where the inundating water is highly saline, saltmarshes are dominated by succulent herbs and shrubs. The most common succulent herb is the beaded glasswort (Sarcocornia quinqueflora
), and a common succulent shrub is shrub glasswort (Sclerostegia arbuscula
). Where inflowing rivers and streams make the water less saline, tussock rushes, tussock sedges, tussock grasses and non-succulent herbs are more prominent. The saltmarsh rush (Juncus kraussii
) is a common saltmarsh species.
Where to see saltmarsh
The most accessible areas of saltmarsh in south-east Tasmania are at Lauderdale, Old Beach on the Derwent River, and on the spit at Marion Bay. In the north excellent saltmarshes can be seen near Port Sorell and Bakers Beach, and near Smithton. However, saltmarshes can be seen in any part of the state in estuaries and sheltered bays.
Biodiversity values of saltmarsh
Saltmarsh is poorly reserved in Tasmania. It contains several rare and threatened plants including the blue wilsonia (Wilsonia humilis
) and the saltmarsh statice (Limonium australe
). Saltmarsh and its adjacent mudflats are used by many migratory birds, some of which are rare or threatened. Saltmarsh stabilises the coast and contributes significant amounts of organic material to estuaries. This is important for the food chain which contains the breeding stock of many commercial and non-commercial fish species. Saltmarshes in the north west and on King Island are important food sources for the endangered orange-bellied parrot (Neophema chrysogaster).
Management of saltmarsh
Some owners of saltmarshes have attempted to drain them for agricultural use. This usually results in salt-scalded, bare ground. Saltmarshes have also been used for rubbish dumping although this practice has largely stopped. Some saltmarshes are used for stock grazing. This can result in a loss of species, soil compaction, and promotion of the few weeds that can invade saltmarsh, such as buckshorn plantain (Plantago coronopus
). While saltmarshes generally recover well after fire (except when the fire is followed by stock grazing), fire is not necessary for their regeneration. Several estuaries in the state, most notably the Tamar estuary, have been invaded by the introduced ricegrass (Spartina anglica
). Ricegrass occupies the intertidal mud flats and reduces bird habitat. As it is difficult to remove once well established, it is important to destroy any colonising plants in estuaries that are largely free of the species.
The major recommendation for saltmarsh is to leave it alone. This means excluding fire and grazing. Ricegrass invasion should be monitored closely. Remove any ricegrass plants that colonise in areas that have not been infested previously. However, care should be taken when removing them because when a plant is broken up each of the fragments can form a new plant.