New research identifies the importance of healthy coastal habitats for combating climate change

Blue carbon ecosystems like seagrasses, mangroves and tidal saltmarshes have exceptional capacity to sequester carbon dioxide. Compared to many terrestrial forests, these coastal vegetation communities can accumulate carbon at faster rates and store it for longer periods, making them an important tool to combat climate change.

The Goyder Institute for Water Research’s Coastal Carbon Opportunities project is among the first to research the potential for coastal systems to help mitigate climate change in South Australia, investigating the potential of South Australian coastal ecosystems to sequester and store carbon.

The two-year project, led by The University of Adelaide, in collaboration with Edith Cowan University, SA Water, SA EPA, and CSIRO, has produced a series of technical and summary reports covering: the impact of degradation on carbon storage and accumulation rates at three case study siteschanges in the distribution of mangrove and saltmarsh across South Australia (1987 – 2015)ecosystem services provided by blue carbon habitatsusing drones to measure mangrove above-ground biomass; and vegetation dynamics at Mutton Cove (a site of tidal reconnection) .

“There’s over a million hectares of seagrass in the state. That ecosystem holds a lot of carbon, and it’s constantly sequestering more carbon every year,” said Dr Alice Jones, Research Associate, The University of Adelaide.

“For the area that they cover they punch above their weight in terms of the amount of carbon that’s stored compared to terrestrial ecosystems,” said Dr Jones.

“Most of the blue carbon values used in the past have been based on tropical coastal ecosystems, so one of our main goals was to get baseline information about blue carbon in South Australia,” said Dr Jones.

The team estimated that South Australia holds around 1.12 million hectares of blue carbon ecosystems, which is as much as 10% of the blue carbon habitat of all of Australia. Blue carbon habitats in South Australia contained about 5% (up to 76 Mt) of the nation’s soil organic carbon stocks, of which about 90% is in seagrass ecosystems. South Australian blue carbon ecosystems sequester 0.11–0.14 Tg Corg y-1 .

The Coastal Carbon Opportunities project provided critical knowledge for the State Government’s Blue Carbon Strategy, recently released by Hon Minister Speirs MP (Minster for Environment and Water), by filling key knowledge gaps and drawing on team members’ expertise on its technical reference panel. They have also contributed to a Blue Carbon Research Projects Synthesis Report and Research agenda for blue carbon in South Australia in partnership with colleagues from the Institute’s Salt to C research project, led by Professor Sabine Dittmann at Flinders University. The research agenda outlines the way forward for blue carbon research in SA as well as opportunities to increase carbon sequestration, potentially with options for carbon crediting.

As well as collecting baseline blue carbon information, the team looked at the effects of human coastal activity on carbon sequestration in seagrass and mangrove/saltmarsh environments.

“We found that the impacted sites had at least two times less carbon than the unimpacted sites,” said Dr Jones, “that information’s helping us understand what the implications are in terms of carbon release when there’s coastal development or changed tidal flow.”

Through the project the team also developed new techniques to measure above-ground mangrove biomass using drones and investigated the value of the ecosystem services that blue carbon habitats provide.

Habitat protection and restoration can increase the carbon sink value of coastal environments, as well as enhance the many other ecosystem services they provide. Highlighting these opportunities in South Australia could be a vital element in remediating coastal vegetation communities and increasing the carbon sequestration and storage capacity of mangrove and saltmarsh ecosystems throughout the state.

You can read more about the project’s research findings below and in the project reports or contact Dr Alice Jones for more information. You can also keep up-to-date with the team’s progress on twitter (@CoastalCarbonSA) or through their project website.

Carbon storage and accumulation rates

The team sampled blue carbon ecosystems in Adelaide coastal waters, Port Broughton, Port Pirie, Port Augusta and Whyalla to obtain initial baseline estimates of the variability in stocks and accumulation rates within and between the different coastal carbon habitats. They found that the seagrass carbon accumulation rate (10.1 Corg m-2 y-1) is significantly lower than tidal marshes (31.1 Corg m-2 y-1) and mangroves (38.8 g Corg m-2 y-1) but that seagrasses account for about 85% of SA’s annual blue carbon sequestration due to their large area (with tidal marshes and mangroves each contributing about 5–10% to annual SA blue carbon sequestration).

The team compared carbon stocks and accumulation rates at disturbed and undisturbed seagrass and mangrove sites and found that historical disturbance reduced their blue carbon stocks and accumulation rates. This suggests that carbon sequestration can be enhanced through ecosystem restoration, and that conservation of these ecosystems will both maintain sequestration and avoid emissions.

Mangrove and saltmarsh distribution (1987 – 2015)
Researchers used Land Cover Layers to estimate the area covered by mangroves (164.2 km2) and tidally-influenced salt marshes (197.6 km2) in 2015 and found relatively small net increases in both ecosystems since 1987. There was a small reduction in the area of saltmarsh between 2005 and 2010 and in the area of mangroves between 2010 and 2015.

The researchers also investigated uncertainty in these area change estimates by comparing mangrove and saltmarsh area estimates and patterns of change from the Land Cover Layers with aerial photographs at Torrens Island and Middle Beach. The aerial photography estimates for both mangrove and saltmarsh appeared to better represent the actual spatial coverage and changes over time. The Land Cover Layers dataset was still the best available state-wide mapping product to use for baseline carbon stock assessment and to identify broad scale gains and losses in saltmarsh and mangrove ecosystems. The findings suggest a multi scale approach is required to accurately estimate blue carbon habitats going forward, which involves further external validation of the Land Cover Layers classification of saltmarsh and mangrove.

Vegetation dynamics at Mutton Cove
Mutton Cove, the last remnant area of saltmarsh and mangrove on the Le Fevre Peninsula, was enclosed by a seawall in the early 1970s and cut off from tidal influence. Consequently, most of the mangroves inside the seawall died-off due to disconnection from tidal flow and only patchy stranded saltmarshes remained. In the early 2000s a restoration program began, to allow controlled tidal flow back into the site and after 10 years the site was restored to a mixture of low and mid saltmarsh communities, with mangroves along the creek edges. In mid-2016 the seawall was breached and the site has since experienced increasing and uncontrolled tidal inundation. Researchers used Mutton Cove as a case study to demonstrate the impact of degradation, restoration and re-introduction of tidal flows into a tidally-restricted saltmarsh area.

Aerial images (dating back to the 1940s), on-ground surveys, physical data collection, and drone-based remote sensing were used to monitor changes at the site. The team found that the building of the seawall and subsequent site degradation led to a significant decrease in sediment carbon stocks and sequestration rates. Since the breach, there has been significant die-off of saltmarsh, especially in lower lying parts of the site, but there has been an increase in the area of mangroves across the site, including lots of mangrove seedlings.

This indicates that in time, with the new tidal regime at the site, the vegetation may eventually return to the mangrove-dominated system that was present prior to the seawall being built in the 1970s.

Using drones to measure mangrove above-ground biomass
The proof-of-concept case study tested a new method for remotely estimating above-ground biomass and carbon stored in mangroves using drones. Drones have the potential to provide a relatively low-cost, low-risk and quick approach to surveying mangrove above-ground biomass when compared to on-the-ground forestry methods that involve physically measuring trees.

The team found that the drone-based imagery can provide very accurate estimates of tree height, but overall tree biomass estimation was better (had lower prediction errors) when they used techniques that rely on taking direct measurements of structural characteristics from the trees in the field. However, with further testing and model development, they aim to improve the accuracy of the drone-based method in order to provide robust estimates of mangrove above-ground biomass.

This study produced a new equation that improves estimates of above-ground mangrove biomass for South Australian Avicennia marina magrove trees compared to other published equations and should be used for future estimation of above-ground biomass in South Australian mangroves.

Ecosystem services provided by blue carbon habitats
Blue carbon habitats provide a wide range of ecosystem services – the benefits provided to humans by ecosystems. Blue carbon habitats provide important ecosystem services including, transport and water supply; recreation and tourism; erosion control; nursery and habitat for fishes, birds and other species; and cultural heritage. The researchers conducted a review to help determine the potential value of co-benefits provided by coastal carbon ecosystems in South Australia.

There was a significant lack of information that clearly linked ecosystem services to monetary or societal values in the South Australian context. The researchers identified the knowledge gaps that currently prevent a complete ecosystem services valuation and analysis. They recommended using case studies in the first instance to clearly demonstrate the value (economic and social) of blue carbon ecosystems and examine the link between ecosystem condition and the ability to provide ecosystem services.

Tags: Carbon Sequestration Climate Action Climate Change Department for Environment and Water (DEW) Healthy Ecosystems South Australia University of Adelaide

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Chris Wright

Manager Water Science, DEW

Chris Wright holds significant experience in public sector senior leadership, having led policy, scientific and operational business units over the last twelve years in both State and Commonwealth government agencies. Chris has excellent experiences in leading policy and strategy formulation. He is skilled in building and maintaining networks across the public and private sectors to facilitate business delivery; leading and negotiating with others to achieve outcomes; and in bridging the science-policy gap, drawing on earlier roles in geospatial information systems (GIS) consulting. Chris’s formal qualifications include a Bachelor of Social Science, a Masters of Spatial Information Science and graduation from the AICD Company Directors course in 2019.

Dr Ilka Wallis

Senior Lecturer, Flinders University

Dr Ilka Wallis is a hydrogeologist with areas of expertise in quantitative hydrogeology and geochemistry. Ilka focuses on the development of reactive geochemical transport models which integrate fundamental processes that are normally studied in isolation (hydrogeological, mineralogical, geochemical and biochemical).

Ilka is also an Adjunct Professor, Department of Civil Engineering, University of Manitoba, Canada since 2017.

Peter Goonan

Environmental Science Branch, EPA

Peter Goonan is the Principal Aquatic Biologist in the Environmental Science Branch of the EPA. He has over 30 years’ experience monitoring the condition of aquatic ecosystems in SA and assessing the environmental effects caused by discharges, deposits and contaminants entering inland and coastal waters. He specialises in aquatic invertebrate identification and their responses to contaminants and water quality stressors. He also provides expert professional advice relating to water quality risks, regulation, policy, and strategic directions, and represents the EPA as an expert witness in court.

Dr Paul Monis

Manager, Research Stakeholders and Planning, SA Water

Dr Paul Monis is a technical expert within SA Water’s Business Services group, which provides scientific expertise to support the delivery of water and wastewater services to SA Water’s customers. He has specialist expertise in the areas of biotechnology and microbiology, with almost 20 years’ experience applying DNA-based and other technologies to address water quality challenges posed by microorganisms, especially enteric pathogens. Dr Monis also holds title of Adjunct Associate Professor at Flinders University, the University of Adelaide and UniSA.

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Principal Advisor Research Partnerships, DEW

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Dr Tanya Doody

Principal Research Scientist, CSIRO

Dr Tanya Doody is a Principal Research Scientist working on high impact spatial eco-hydrological projects within CSIRO’s Land and Water Business Unit. Dr Doody leads the Managing Water Ecosystems Group, based in Adelaide, Albury and Canberra and has significant experience in quantifying the water requirements of vegetation and at times, their impact on water resources. This involves ecophysiological field-based research to underpin remote sensing tools to scale regionally to improve our understanding of the effect of flood regimes on the health of water-dependent ecosystems on the Murray-Darling Basin floodplains. Additional research includes investigating the ecological response of vegetation to water availability and environmental water to inform integrated basin water planning and management.

Professor Lin Crase

Dean of Programs (Accounting & Finance), UniSA

Professor Lin Crase is Professor of Economics and Dean of Programs (Accounting & Finance) at UniSA. He joined UniSA in February 2016 as Head of School of Commerce. Prior to commencing at UniSA, Lin was Professor and Director of the Centre for Water Policy and Management at La Trobe University.

Lin’s research has focused on applied economics in the context of water. He has analysed water markets and the property rights that attend them, water pricing and numerous applications of water policy. Whilst his expertise includes the Murray-Darling Basin in Australia, he has also worked on projects in south Asia, Japan and Europe. Lin has published over 100 journal articles, numerous book chapters, four books and a range of other papers and opinion pieces.

Professor Justin Brookes

Director, Water Research Centre, University of Adelaide

Justin has broad research interests in limnology and water treatment with a primary focus on coupling between hydrodynamics, biology and water quality contaminants such as cyanobacteria and pathogens. He is a founding member of the management committee of the IWA Specialist Group on Lake and Reservoir Management and member of the Steering Committee for the Global Lakes Ecological Observatory Network.

Justin has a PhD and a Bachelor of Science degree with Honours from the University of Adelaide.

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Daniel Flaherty is the Accountant for the Goyder Institute for Water Research.

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Daniel is a Fellow of CPA Australia and has a Bachelor of Economics from the University of Adelaide.

Dr Alec Rolston

Interim Director

Alec Rolston joined the Institute in 2021 as Research Program Manager of the Goyder Institute’s research projects in the Healthy Coorong, Healthy Basin program. He has extensive experience in integrated water resource management, integrated catchment management, drinking water source protection and wetland ecology, conservation and management across Europe and Australia.

Alec holds a PhD from the National University of Ireland Maynooth and has worked with An Fóram Uisce|The Water Forum and the Dundalk Institute of Technology in Ireland as well as the MANTEL Innovative Training Network across Europe.

Alec spent his early career in Adelaide working with Flinders University through the Coorong, Lower Lakes and Murray Mouth (CLLAMM) Ecology Research Cluster and within the Department for Environment and Water.

Daniel Pierce

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Daniel Pierce has managed research projects at the Goyder Institute for Water Research since November 2017 under both the second and third terms of the Institute.

Daniel brings experience in project management and knowledge transfer and application from 4 years working as a Senior Hydrogeologist in the Department for Environment and Water (DEW) in South Australia and from 13 years of private sector work in environmental management, science and engineering in Australia and the South Pacific. His work with DEW has included providing technical advice to the development and revision of Water Allocation Plans around South Australia in collaboration with researchers and policy makers, and managing a team of groundwater modellers and hydrogeologists involved in an assortment of water resource management issues.

Daniel has a Bachelor of Engineering (Hons, Environmental) and a Bachelor of Science (Geography) from the University of Western Australia.

Professor Enzo Lombi

Dean of Research, UniSA STEM

Professor Lombi’s main contributions to environmental research cover various aspects of contaminant risk assessment, biogeochemistry, ecotoxicology and waste management. Furthermore, the methodological development he has pursued in his research has provided the basis for collaborative efforts in a variety of research areas ranging from soil fertility and plant physiology to human health issues related to contaminant uptake via occupational exposure and diet. In the last few years he has been increasingly focusing on the transformation and toxicity of manufactured nanomaterials in the environment.

Dr Carmel Pollino

Research Director Land and Water, CSIRO

Dr Carmel Pollino is a Research Director for Land and Water at CSIRO. She has 20 years of experience working on water issues in Australia and throughout Asia. Carmel has degrees in science and environmental law and works across the science and policy interface. Significant areas of research in Environmental Flows, Hydrology, Ecology and Integrated River Basin Planning. Carmel is the lead and also a contributor to global working groups on water and has published widely in this domain.

Professor Bronwyn Gillanders

Head of School of Biological Sciences, The University of Adelaide

Professor Bronwyn Gillanders is interim Head of School of Biological Sciences at the University of Adelaide. Prof Gillanders completed her BSc at the University of Canterbury, MSc at the University of Otago and her PhD at the University of Sydney. She has a research background in environmental science focused predominantly on freshwater and marine ecology.

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Director, Water Security, Policy and Planning, Department for Environment and Water (DEW)

Dan Jordan is the Director, Water Security, Policy and Planning, Department for Environment and Water (DEW). Dan is also the Basin Officials Committee Alternate Member for South Australia.

Professor Okke Batelaan

Dean, School of the Environment, Flinders University

Professor Okke Batelaan is a graduate of the Free University of Amsterdam, Netherlands (MSc – Hydrogeology) and of the Free University Brussels, Belgium (PhD – Engineering). He worked for more than 20 years at the Free University Brussels and also led the hydrogeology group at the KU Leuven, Belgium since 2006. He was chairman of the Interuniversity Programme in Water Resources Engineering.

Since 2012 Okke Batelaan is Strategic Professor in Hydrogeology and currently Dean of the School of the Environment, Flinders University. Okke has broad experience in teaching groundwater hydrology, groundwater modelling, GIS and remote sensing for hydrological applications. He was supervisor of more than 140 MSc and 25 PhD students. He has extensive research experience and a publication record in shallow groundwater hydrology and modeling, recharge-discharge estimation and modeling, urban hydrology and distributed modelling, ecohydrology and impacts of land use and climate change on groundwater systems. He coordinated and participated in a large number of projects in Europe, Africa, South America, Asia and Australia. He is editor-in-chief of Journal of Hydrology: Regional Studies and of MDPI-Hydrology.