The tide is turning
on coastal health

Professor Sabine Dittmann

“When I look at mudflats, I see an upside-down forest.” It’s an important view that defines ecological insight for Professor Sabine Dittmann, Professor of Marine Biology at Flinders University, whose focus on tidal wetlands is central to the conservation and restoration of coastal ecosystems.

Professor Sabine Dittmann

Her knowledge of mudflats helps define the vast ecosystem beneath the mud surface, facilitating habitat for huge numbers of species that interact and thrive in a healthy environment.

Of importance is Professor Dittmann’s work applying this knowledge to improve the health of the Coorong, where salt levels are concentrating to concerning levels in the southern part, with salinity up to four times higher than sea water.

“In some areas of the Coorong, salinity levels are so high that an accumulating toxic black mud is making it uninhabitable for many invertebrates that support the health of the whole ecosystem,” she says.

Fortunately, her research team is finding that such conditions can be reversed. “We have been able to do controlled experiments on site and in real-time that have had incredible results for sediment and water quality improvements. Within a few weeks, we saw significant change in the sulphur concentration of the mud. Worms came back and made the whole system come alive. The turnaround was remarkable.”

This project is part of the South Australian Government’s Healthy Coorong, Healthy Basin Program (HCHB), which is jointly funded by the Australian and South Australian governments. The Goyder Institute for Water Research, of which Flinders University is a partner, is delivering five research components of the HCHB program, providing independent research to inform future management decisions for the region. These Goyder-led projects will be completed by mid 2022.

The ramifications of ensuring the Coorong’s health as an ecosystem are huge, and not just for fish and marine life. It serves as a crucial feeding ground for many migratory shorebird species – such as red-necked stint and sharp-tailed sandpiper that migrate annually from Siberia. The main prey items of these shorebirds are macroinvertebrates, which Professor Dittmann’s team measures each year to determine changes in the condition of the Coorong. With food volumes reduced in a compromised Coorong, the long-term survival of these bird populations will be severely threatened. Through this research, her team is now able, for the first time, to also analyse the nutritional value of prey items, to find out whether the birds can get enough energy for their return journey.

Professor Dittmann brings a global perspective to the understanding of mudflats, having done her initial studies in Germany’s Wadden Sea (a UNESCO World Heritage Site), and then further studies in tropical northern Queensland, before coming to Flinders University and doing critical examination along South Australia’s temperate coastline. Her work on tidal wetlands also includes mangrove and saltmarsh, which are important carbon sinks in the emerging Blue Carbon conversation.

The Blue Carbon term, introduced globally in 2009, refers to the natural carbon sequestration in coastal and marine ecosystems. By restoring and increasing the area of Blue Carbon ecosystems, carbon is captured and stored, a nature-based solution to mitigate climate change. Yet, when these ecosystems are degraded, lost or converted to other land uses, the large stores of Blue Carbon are exposed and released as CO2 into the atmosphere.

South Australia holds an estimated 1.12 million hectares of Blue Carbon ecosystems (more than seven per cent of Australia’s Blue Carbon habitat) with seagrass beds accounting for 96%, and tidal saltmarsh and mangrove comprising about two per cent each, but with much higher carbon storage per hectare.

Professor Dittmann’s work on assessing and monitoring carbon capture and storage provided a pivotal basis for Blue Carbon projects and policy in South Australia – from the St Kilda mangroves to ongoing transformation of a Dry Creek salt pond, which has become a national pilot project for the reintroduction of tidal flow to former salt harvesting sites.

Introducing positive change through rehabilitation was the focus of the Salt to C Project, delivered through the Goyder Institute for Water Research. Professor Dittmann’s team found that reintroducing tidal flows to one pond in the Dry Creek salt field worked well and could gain carbon credits as restoration through tidal flows, providing substantial carbon offset opportunities.

Bringing her expansive knowledge to the St Kilda mangroves is crucial in trying to solve an ongoing problem of plants dying due to high salt concentration. Funded by the Blue Carbon Futures Fund of the Green Adelaide Landscape Board, Professor Dittmann’s team is assessing the health of the mangrove and its carbon storage, to quantify effects of the dieback on the Blue Carbon storage of the mangrove.

“Building on our foundational projects, further research on Blue Carbon can make South Australia a leader in integrating coastal management and climate change mitigation.”

While she says many coastal systems in South Australia are in quite good shape, and guarded by legislation, Professor Dittmann still worries about possible future developments compromising the outcomes of the state’s Blue Carbon future.

“We have pristine systems in place that we can monitor – many of which are unique in the world – but there are still great risks that these fragile environments can be damaged, especially with developments and restrictions to inland migration with sea-level rise,” she says. “Our data presents strong arguments for more stringent protection, to safeguard our Blue Carbon future.”

The sum of this research and engagement provides an important qualifier to enable continued coastal restoration, and Professor Dittmann is confident of attracting growing amounts of corporate and industrial support. “We are seeing many companies wanting to take responsible action. For example, fisheries want protection and increase of fish nursery habitats and they want to benefit from carbon offsets. It’s a double win.”

She therefore hopes her research will provide evidence for even tighter environmental legislation, while also providing a framework for future Blue Carbon projects once the Clean Energy Regulator has determined a methodology to earn Australian carbon credit units through tidal restoration.

“The conservation, restoration and creation of stronger coastal ecosystems not only has the potential to mitigate climate change, but also provide many other important ecosystem services, such as improved water quality, tourism, fisheries and shoreline protection.”

The way forward demands different thinking and action – and Professor Dittmann is keen to see more Indigenous knowledge incorporated in future ecological management plans and practices.

She sees that this expansive view of improved environmental management will have global benefits.

“We are leading the way with this measurement of carbon and biodiversity, and our work will be of great value in many parts of the world where environmental degradation must be urgently addressed.”

Professor Sabine Dittman

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