The Coastal Carbon Opportunities project is among the first to research climate change mitigation in coastal systems. The Goyder Institute for Water Research team, led by Professor Bronwyn Gillanders (University of Adelaide), are investigating the potential of South Australian coastal ecosystems (seagrass, mangrove and saltmarsh) for carbon sequestration and storage. 

To help demonstrate the additionality and potential for future offsets, the team is estimating baseline carbon stocks and carbon accumulation rates, as well as carbon storage dynamics at case study sites along the South Australian coast. The data collected will contribute to providing SA-specific estimates of ‘blue carbon’ resources and help assess sequestration and emissions-abatement opportunities in SA and beyond.

The project, a collaboration between the University of Adelaide, CSIRO, SA Water and the Department for Environment and Water (DEW) has reached its half-way mark and made significant progress towards its objectives. In addition to the field work outlined below, the team are completing a literature review on SA coastal carbon and a meta-analysis of SA coastal ecosystem services.

Sediment sample collection and analysis
More than 20 sediment cores from three case-study locations in seagrass and mangrove systems have been collected, completing the sediment sample collection aspect of the project. The team have also analysed samples from cores (dating and carbon content) and mangroves (carbon content, isotope ratios and biomass measurements). This data will be key to characterising the carbon sequestration potential of SA mangrove and seagrass ecosystems and how impacts on these systems can affect their carbon sequestration and storage capacity.

The team also installed sediment elevation tables (SETs) at all case study sites, and have taken measurements from the SETs—over time this data will provide insights into sediment (and carbon) accumulation rates. The team also installed water level loggers at the mangrove sites to better understand the effect of tidal flow on sediment and carbon accumulation.

Assessing broad-scale change in mangrove and saltmarsh distribution
The team are using Landsat remote-sensed data and aerial photography from DEW to assess changes in mangrove and saltmarsh distribution across the state – this work is well underway. They’ve also begun developing methods to externally validate the state-wide assessment as it became clear there are uncertainties associated with the Landsat remote-sensed data (land-cover dataset). Aerial imagery from various time points at specific locations, such as Torrens Island, is being compared to changes found using the Landsat data.

Drone-based methods for surveying mangrove biomass

A pilot study on the potential to use drone-based methods to survey mangrove biomass is well advanced, with the resulting aerial imagery used to develop a model of mangrove biomass. The team are now preparing this study for publication. Repeat drone surveys have also been carried out at the Mutton Cove case study site and will continue into early 2019. Along with on-the-ground vegetation surveys, these surveys will provide detailed insight into vegetation health and distribution changes associated with the breached seawall (and changed tidal inflow) at the site.

New opportunities 

The team have successfully leveraged the project to receive further funding from the Hermon Slade Foundation. This is supporting a PhD student (Nicole Foster), who is looking at environmental DNA (eDNA) through core samples to identify change in coastal vegetation communities over time. This is an important development for coastal carbon work, as it will allow the project team to better constrain the vegetation communities present at different points in time and relate the carbon sequestered at that time to the associated vegetation communities. Currently, carbon sequestration projects assume that the contemporary vegetation type represents the historic vegetation type.

The project continues to contribute to the strategic intent of the Goyder Institute — to support world-leading water and natural resource management in South Australia through excellent science.

The project team has worked closely with the DEW on analysis of spatial datasets and are involved in discussions with the State government about strategies to develop blue carbon opportunities in South Australia. They’ve also presented their findings at a range of local, national and international conferences and attended workshops focused on developing methods for including blue carbon projects into the Emissions Reduction Fund and the Verified Carbon Standard offsetting scheme. The project team collaborates closely with the other blue carbon related Goyder Institute project 'From Salt to C: carbon sequestration through ecological restoration at the Dry Creek Salt Field'.

For more information about the project, contact project leader Professor Bronwyn Gillanders or you can keep up-to-date with the team’s progress on twitter (@CoastalCarbonSA) or through their project website.

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