Saltmarsh ecosystems are protecting more than 88,000 homes from storm surges and are sequestering carbon at a rapid rate, according to the Australian Bureau of Statistics.
The data was released as part of the federal government's National Ocean Ecosystem Account, which showed the marshes sequestered about 10 million tonnes of carbon dioxide in 2021.
In the past saltmarshes and mangrove swamps have been viewed as wastelands with little economic value.
But their ability to absorb eight times as much carbon at 35 times the rate of "land-based" forests, according to Local Land Services (LLS), is one of the factors driving the effort to save them.
The agency is working with farmers to fence off saltmarshes on private land.
Fences up
Shoalhaven dairy farmer Paul Anderson says he enjoys having a mix of wetlands and productive pastures on his Pyree property.
"This place here is about 200 acres … probably about 80 acres of it is saltmarsh," he said.
"The saltmarsh is pretty low country and you can't make any feed or silage off it, so it's just a holding paddock for cows.
"If we can beautify it a bit more, that's good — because we do have a bit of a wetland area with a few birds there and water all the time."
Mr Anderson and his brother Keith are working with LLS to fence off 17 hectares.
About 80 per cent of the area is saltmarsh.
The remaining 20 per cent is made up of mangroves and swamp oak forest.
LLS senior land services officer Sonia Bazzacco said there was funding available to help farmers fence off key saltmarsh areas.
"This is a really large significant area that the Andersons are putting aside towards having an environmental gain," she said.
"I've been approaching a lot of farmers in Pyree, because there's actually 220 hectares of saltmarsh in the Shoalhaven.
"That's the largest area of saltmarsh in the whole of south-east New South Wales."
Key habitats
Threats to coastal salt marsh include development, uncontrolled livestock, the rising sea level and mangrove incursion.
"The first step really is to exclude stock off these very sensitive areas," Ms Bazzacco said.
Saltmarshes are a key breeding habitat for fish, birds and crustaceans.
It has been estimated that mangrove-related species in eastern Australia account for about 67 per cent of the entire commercial catch.
Recently saltmarshes and mangroves have attracted more funding for restoration work as countries around the world look to invest in a blue carbon strategy.
"A lot of people don't realise is that coastal saltmarsh is able to absorb eight times as much carbon [at] 35 times the rate than a land-based forest," Ms Bezzacco said.
"It's also very important in improving water quality.
"The saltmarsh acts as a buffer between the terrestrial and aquatic environment.
"Sediment and farm run-off, such as nitrogen and contaminants, are actually filtered through and absorbed and recycled by the saltmarsh."
Earlier this year the Albanese government invested $9.5 million to support five new practical restoration blue carbon projects.
Environment and Water Minister Tanya Plibersek said in a statement that saltmarshes also protected homes.
"Over 19,000 kilometres of our coastline are being protected from storm surge by mangrove and saltmarsh ecosystems," she said.
"If these were lost it would cost over $225 billion to replace their coastal protection services with seawalls.
"This new data clearly shows how important they are and how many of us living along the coast of Australia benefit [from their protection], possibly without even realising."
