3.5.1 Saltmarshes

Saltmarshes are important coastal ecosystems that occur mostly in the upper intertidal area of low-gradient marine and estuarine plains. 

They are part of a mosaic of habitats, including mangrove forests and seagrass meadows that provide important hydrological connections between terrestrial and marine environments.919,937,938

Saltmarsh vegetation typically comprises low-growing herbs, grasses, sedges and shrubs; only occasional emergent trees are present, if at all. Saltmarshes occur discontinuously along the entire Region coastline.935

Saltmarshes play a vital role in carbon sequestration

Saltmarshes provide intermittent feeding areas for several marine species, including commercial fishery species, such as bream, whiting, mullet 939 and tiger prawns.940 They also provide feeding and resting areas for resident and migratory birds.935 The important role played by saltmarshes in carbon sequestration 117,941 led to their inclusion in the National Ocean Ecosystem Account in late 2022,127 an important step towards systematic monitoring of saltmarsh condition in the Region.

Saltmarshes have historically been extensively drained and removed, as well as affected by the construction of structures such as roads and causeways that alter their hydrology and drainage, including bund walls used to retain freshwater upslope for ponded pastures.942 Such structures are now better regulated because of statewide regulatory controls that prohibit the construction of infrastructure like ponded pastures since the early 2000s through the Policy for Development and Use of Ponded Pastures 2001 (Qld).943 However, ongoing issues persist in some areas due to the presence of existing structure and reclamation in developed coastal areas.942 Projects have been successfully undertaken on a limited scale since 2014, such as removing bunds in the Mungalla wetlands east of Ingham to re-establish connection through culverts.938,944

No significant changes in extent of saltmarshes are reported since 2019,110 although local-scale declines in saltmarsh grass have been detected in recent years.121 As with mangroves, saltmarshes are dynamic ecosystems known for their ability to adapt to environmental changes, such as rising sea levels (see 3.2.5). However, the ability of marshes to grow vertically by accreting sediment is limited, leaving marshes vulnerable to future sea level rise.95

No significant changes in saltmarsh extent have occurred since 2019. However, little is known about saltmarsh condition, which is not currently monitored systematically across the Region. In future, both the extent and condition of saltmarshes are likely to be affected by rising sea levels.

  • 95. Saintilan, N., Horton, B., Törnqvist, T.E., Ashe, E.L., Khan, N.S., et al. 2023, Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C, Nature 621(7977): 112-119.
  • 110. State of Queensland (Department of Environment Science and Innovation) 2023, Biodiversity status of pre-clearing and 2021 remnant regional ecosystems - Queensland series, Version 6.13 edn.
  • 117. United Nations Educational, Scientific and Cultural Organization 2024, Blue Carbon, <https://www.ioc.unesco.org/en/blue-carbon>.
  • 121. Chamberlain, D., Phinn, S. and Possingham, H. 2020, Remote sensing of mangroves and estuarine communities in central Queensland, Australia, Remote Sensing 12(1): 197.
  • 127. Department of Climate Change Energy the Environment and Water 2024, National Ocean Ecosystem Account, Commonwealth of Australia, <https://eea.environment.gov.au/accounts/ocean-accounts/national-ocean-ecosystem-account>.
  • 919. Waterhouse, J., Pearson, R., Lewis, S., Davis, A. and Waltham, N. 2024, 7. Great Barrier Reef ecohydrology, in Oceanographic Processes of Coral Reefs. Physical and Biological Links in The Great Barrier Reef, eds E. Wolanski and M.J. Kingsford, CRC Press, Boca Raton, pp. 105-125.
  • 935. Jaensch, R. 2005, Wetland Management Profile: Saltmarshes, Department of Environment and Science (Qld).
  • 937. Meynecke, J., Lee, S.Y., Duke, N.C. and Warnken, J. 2007, Relationships between estuarine habitats and coastal fisheries in Queensland, Australia, Bulletin of Marine Science 80(3): 773-793.
  • 938. Abbott, B.N., Wallace, J., Nicholas, D.M., Karim, F. and Waltham, N.J. 2020, Bund removal to re-establish tidal flow, remove aquatic weeds and restore coastal wetland services—North Queensland, Australia, PLoS One 15(1): e0217531.
  • 939. Thomas, B.E. and Connolly, R.M. 2001, Fish use of subtropical saltmarshes in Queensland, Australia: relationships with vegetation, water depth and distance onto the marsh, Marine Ecology Progress Series 209: 275-288.
  • 940. Taylor, M.D., Becker, A., Moltschaniwskyj, N.A. and Gaston, T.F. 2018, Direct and indirect interactions between lower estuarine mangrove and saltmarsh habitats and a commercially important penaeid shrimp, Estuaries and Coasts 41(3): 815-826.
  • 941. Perera, N., Lokupitiya, E., Halwatura, D. and Udagedara, S. 2022, Quantification of blue carbon in tropical salt marshes and their role in climate change mitigation, Science of the Total Environment 820: 153313.
  • 942. Wegscheidl, C., Sheaves, M., McLeod, I.M. and Fries, J. 2015, Queensland's saltmarsh habitats: Values, threats and opportunities to restore ecosystem services, James Cook University, Townsville.
  • 943. Department of Natural Resources and Mines 2001, Policy for Development and Use of Ponded Pastures, Department of Natural Resources and Mines, Brisbane.
  • 944. Luke, H., Martens, M.A., Moon, E.M., Smith, D., Ward, N.J., et al. 2017, Ecological restoration of a severely degraded coastal acid sulfate soil: A case study of the East Trinity wetland, Queensland, Ecological Management & Restoration 18(2): 103-114.