Saltmarsh are intertidal wetland plant communities made up of a mosaic of succulents, grasses, low shrubs and saltpans. They commonly occur in upper intertidal zones between the mangrove fringe and more terrestrial vegetation.

The saltmarsh environment is much more extreme than that of mangroves, with more variable and higher salinities, no shade (hence higher sunlight on the ground and greater exposure to wind) and less frequent tidal incursions, giving rise to periods of very low soil moisture content.

Saltmarshes may be bare or vegetated. Bare saltmarshes are termed “salt flats” or “salt pans” and their existence indicates hypersaline conditions.

Vegetated saltmarshes fall into two categories: those dominated by sparse to medium density dwarf shrubland of semi-woody plants (samphires) and those dominated by sparse to dense, low tussock grassland.

Saltmarsh is considered a wetland community.

Saltmarsh, Susan River - Maryborough

Soil and Geology:

The substrate of saltmarsh is normally deep grey or black clay of marine origin and is low in oxygen.

Relationship with fire:

This vegetation community is naturally fire tolerant when inundated, providing natural firebreaks and a refuge for animals during bushfires. In drought conditions or in wetlands with altered drainage, which has resulted in drier conditions and altered species composition, can increase the risk of more frequent and severe fires. Severe fires can lead to the exposure of acid sulfate soils.

More research is required to better understand the appropriate fire regimes (frequency, intensity, and season of occurrence – if any) is required to protect the ecological values of this community. Fire sensitivity does vary within this vegetation community and degradation of habitat values has been reported post fire.

Fire has been used in Northern Queensland areas to manage exotic pasture grasses like Para grass (Brachiaria mutica) and Hymenachne (Hymenachne amplexicaulis).

Threats:

  • The exclusion of tidal or freshwater inflow from the construction of seawalls, bunds, roads, bridge embankments and industrial infrastructure through wetland, with inadequate piping for water exchange or none at all.

  • Development and expansion of agricultural practices e.g. sugarcane

  • Pollution runoff from residential, industrial and agricultural land use.

  • Sedimentation from flooding.

  • Inappropriate grazing regimes.
  • Feral animals, particularly pigs.
  • Weeds.
  • Off-road vehicle use.
Encroachment of agricultural practices into wetland areas - impacting the extent and health of the vegetation communities, including saltmarsh.
Cattle impact on saltmarsh and mangrove vegetation, Susan River - Maryborough
Pig impact on saltmarsh, Susan River - Maryborough

Values:

  • Nutrient recycling.
  • Significant carbon storage.
  • Support a range of species including fish, crabs, prawns, molluscs, worms and waterbirds. They provide nursery habitat for species of ecosystem, commercial, recreational and Indigenous food value.
  • Important habitat for migratory shorebirds.

Management Considerations:

Saltmarsh wetlands mainly fall under the management of local and state government. However, some private ownership does occur, and private land can adjoin saltmarsh wetlands.

Land managers with saltmarsh systems on their property or living adjacent to this vegetation community should take the measures to reduce their impact on this wetland. This may be fencing the area from livestock, creating a buffer between your property and the saltmarsh system (approx. 50-100m), disposing chemicals and wastewater appropriately, and avoid vehicle and foot traffic.

It is often that this wetland may be part of a broader wetland complex e.g. connecting to paperbark woodlands, mangroves and grass-sedge swamps. This needs to be considered when identifying management actions for this vegetation community.

Where degradation or damage to vegetation is evident, landholders are advised to gain expert advice on appropriate remediation options for the site.

Wetland buffers:

A useful tool of protecting wetland biodiversity and ecological values is by maintaining a buffer zone of intact vegetation. Buffer distances range from 50-200 meters.

The buffer is used to reduce the impact from adjacent land uses. Its role is to:

  • Trap and filter sediment and nutrients from surface run-off, from land distant to the wetland,

  • Providing a physical barrier to herbicide and pesticide spray drift from adjacent agricultural activities and mosquito control measures

  • Providing an attractive visual barrier from adjacent land uses.

There are specific guidelines for wetland buffer zones under local and state government legislation where development is being undertaken adjacent to the wetland area.

Fisheries Act 1994 and Declared Fish Habitat:

Marine plants in Queensland are protected under the Fisheries Act 1994, which includes the protection of all marine plants, including mangroves, seagrass, salt couch, salt marshes etc. This act also controls activities such as the collection of dead wood and algae for aquariums hobby use. These environments are further categorised as Declared Fish Habitat under the Act acknowledging their vital role in sustaining fish stocks for recreational, commercial, and Indigenous fishing.

This Act is put in place to help protect these valuable marine environments from inappropriate development, such as construction of roads, water crossings, pontoons and jetties etc. Removal or damage of saltmarsh vegetation is illegal without approval. The Fisheries Act 1994 requires land managers to undertake an approval process for development activities, where removal or damage to marine plants will occur. To learn more about this process please visit, here.

We encourage landholders to report sightings of Mangrove and other marine environment damage to the Fishwatch Hotline on 1800 017 116. The Queensland Boating and Fisheries Patrol can issue on-the-spot fines for damage to marine plants and fish habitats. Significant penalties may apply, and serious cases are taken to court.