Dry Creek salt field prepares for green future

The restoration of the Dry Creek salt fields north of Adelaide is part of a State Government push for carbon neutrality.

Under the Goyder Institute for Water Research ‘Salt to C environmental project – led by Professor Sabine Dittmann from Flinders University – the blue carbon work has already resulted in a revival of plant life in one salt pond after 18 months of tidal reconnection.

The investigations will generate knowledge and data on bio-sequestration and carbon abatement through revegetation of salt fields.

After salt production ceased at Dry Creek, the research is looking for emissions abatement through carbon sequestration and/or emission avoidance as a result of long-term revegetation.

Blue carbon is the term used to describe carbon captured by ocean and coastal ecosystems.

Professor Dittmann, with fellow university researchers and experts from the State Government and private sector, says tidal re-connection is a top priority activity recommended by a national blue carbon working group for establishing a methodology under the Emissions Reduction Fund for blue carbon.

“The project is of nationwide interest as a proof of concept for blue carbon benefits from tidal re-connection and salt field restoration,” she says.

The scientists have investigated changes in the carbon stocks in sediments and vegetation and greenhouse gas fluxes, within the pond and adjacent reference areas.

“There has been a net gain of organic carbon in the sediment surface layers, mostly likely through seagrass (wrack) accumulating in the pond,” says marine biologist Professor Dittmann, from the College of Science and Engineering at Flinders University.

“While long-term sediment accumulation rates were highly variable in and outside of the pond, surface elevation tables are indicating recent sediment deposition since reconnection.

“The flux of greenhouse gases also varied by elevation, with emissions at higher elevation and uptake of CO2 in lower lying areas with moister sediments.

“The comparison between the trial pond and reference area indicates that further restoration of vegetation within the pond can reduce emissions.”

The salt pond before intertidal connection in 2017.

Based on the elevation and predicted vegetation changes, most of the pond can be recolonised by mangrove.

Measurements from adjacent mangrove forests have yielded an average above ground biomass of 240 t dry mass per ha, equivalent to 413 tCO2e per ha, according to Professor Dittmann’s update.

The biomass estimate is higher than reported for other temperate mangroves and could indicate the potential for carbon benefits through restoration of mangrove forests.

“Saltmarsh plants have been the fastest colonisers in the pond and their arrival was subject to seasonal differences in seed dispersal, which was detected with monthly deployment of seed traps,” she says.

“On a very positive note, the saltmarsh plants now established within the pond are flowering and setting seed, which can accelerate further recolonisation.”

The interdisciplinary project involves scientists from Flinders University, the University of Adelaide, the University of South Australia, the Department for Environment and Water, as well the Australian National University and Silvestrum Climate Associates.

Flinders University is also involved in several other environmental rehabilitation Goyder projects in South Australia including:

In November, Emeritus Professor Michael Barber AO, FAA, FTSE gave a Goyder lecture on the UN Sustainable Development Goals, hosted by the National Centre for Groundwater Research and Training and Flinders University.

Read more at the Goyder Institute website. The Goyder Institute brings together leading researchers to support government water resource policies.

 

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College of Science and Engineering

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