Coastal salt marsh fact sheet

What is a salt marsh?

Coastal salt marsh is a low flat wetland found alongside tidal creeks, rivers, bays and estuaries. They thrive in the intertidal zone where very high tides submerge them in salty water and low tides reveal them. These marshes support a variety of salt-tolerant plants and are crucial for coastal ecosystems.

Salt marsh at Kittys Creek. Salt marshes develop on muddy or sandy sediments where tidal movement, salinity and elevation are ideal.

Where are coastal salt marshes found?

Coastal salt marshes are wetlands regularly flooded by tidal waters. They’re found in temperate and subtropical estuarine areas where freshwater from rivers and creeks meets salt water from the ocean. These low-lying coastal areas are typically found in protected areas, such as estuaries, bays, lagoons, tidal creeks and rivers and sheltered coastlines.

Coastal salt marshes are found in various locations across Sydney, including the Parramatta River, Sydney Olympic Park and Towra Point Nature Reserve. Lane Cove River and its tributaries, including Buffalo and Kittys Creek, also contain salt marsh.

Salt Marsh along the Coquun/Hunter River - Hunter Wetlands National Park.

Why are coastal salt marshes important?

In NSW this ecosystem is officially protected because it is an Endangered Ecological Community, and it is listed as vulnerable under Australia’s environment laws.

Salt marshes are special ecosystems vital for both biodiversity and human well-being. They provide a haven for shorebirds like the Sharp-tailed sandpiper and other wildlife, offering a place to rest and feed.

Coastal salt marshes act as a natural barrier protecting coastal environments from storm surges, floods, erosion, wind and waves. The plants slow down the waves and trap mud safeguarding the shoreline. This protection is becoming increasingly crucial as climate change and rising sea levels threaten coastal areas. Salt marshes stabilise the soil, filter pollutants, recycle contaminants and nutrients, maintaining and improving water quality.

Sharp-tailed sandpipers have a long thin beak to help find food in salt marshes.

What plants grow in salt marshes?

Saltmarsh plants are adapted to growing in salty, waterlogged soils. In Sydney you might see samphire/beaded glasswort, saltwater couch, sea rush and creeping brookweed. These plants can make the marsh look green in some places and red in others.

Samphire or beaded glasswort is often red, creating a carpet of colour in salt marshes at Towra Point Nature Reserve, Botany Bay.

Samphire close up.

Grey mangrove seedlings can spread into salt marsh areas.

What animals live in salt marshes?

Salt marshes support a thriving community of invertebrates like crabs, snails, amphipods and worms. The marsh’s edges and nearby creeks serve as nursery grounds for small fish. Shorebirds including migratory species forage across the marsh and mudflats probing for worms and tiny crustaceans.

Haswell’s shore crab can be found in some salt marshes.

How are salt marshes used by Aboriginal Peoples?

Saltmarsh has long provided people with food and material resources. Edible samphires can be harvested sustainably, and rushes such as juncus can be used for weaving.

Juncus was used for weaving.

What threats do mangrove forests face?

Salt marsh has been lost due to land filling, altered tidal flows and pollution. Weeds can then establish and trampling by people, pets and vehicles further damages the soft ground and plants. Furthermore, mangroves are encroaching on former salt marsh areas. Rising seas and climate change exacerbate these pressures.

We can care for salt marsh by staying on paths and boardwalks.

Boardwalks help to protect salt marsh areas from foot traffic.

Related Fact Sheets

Environments & ecosystems

• Mangrove forest fact sheet

• Eucalypt forest fact sheet

• Field of Mars Reserve fact sheet

Habitats

• Water habitats fact sheet

• Rock and log habitats fact sheet

Animals commonly found in salt marshes

• Red-fingered marsh crab fact sheet

• White ibis fact sheet