Blue carbon ecosystems, such as mangroves, saltmarshes and seagrasses, play critical roles in climate change mitigation and adaptation. Victoria is home to vast areas of these natural climate solutions, where large-scale research has uncovered their importance and the many ecosystem services they provide. On a local scale, it is increasingly important to understand the opportunities to maintain and restore these blue carbon ecosystems, to help contribute on the path to net zero carbon emissions.
The regions Western Port Bay and eastern Port Philip Bay hold nearly a quarter (24%) of Victoria’s coastal blue carbon ecosystems and have substantial potential to capture even more carbon, through restoring areas that have been damaged or lost over time. To understand how to do this, Western Port Biosphere Reserve Foundation (WPBRF) has partnered with Blue Carbon Lab, along with local member councils of the South East Councils Climate Change Alliance (SECCA), to identify local scale opportunities to manage these ecosystems for a climate positive future.
“Land clearance and degradation of the world’s forests regularly hit the international news as a threat to the Earth’s capacity to absorb carbon dioxide. Yet the loss of marine ecosystems on our doorstep and around the world and the equally substantial role they play in maintaining a liveable planet slips by virtually unnoticed. Globally, wetlands have already declined by 64-71% since 1900.”
Uncovering local blue carbon opportunities
The Blue Carbon Lab team, led by Dr Micheli Costa, Dr Maria Palacios, and Prof Peter Macreadie, estimated the past and current distribution of mangrove forests, seagrass beds and saltmarshes throughout seven Local Government Areas to explore the key role these wetlands are playing in providing ecosystem services, and understand their restoration potential.
The researchers found that blue carbon ecosystems in the area currently capture nearly a third of Victoria’s blue carbon (31.5%) and provide an array of ecosystem services to the region. These include benefits like capturing carbon (8.9 million tonnes CO2e), fixing nitrogen (>400 tonnes N yr−1), benefitting commercial fisheries (>60 million kg fish yr−1) and providing coastal hazard mitigation for many nearby properties (>45,000). However, when the team took to historical maps, they discovered that some of these areas have been lost over time, finding declines in saltmarsh habitat (16%) and mangrove forests (5%) since European settlement, while seagrass cover has grown (40%) since 1960.
Future management for lasting impact
Taking a focus on mangroves and saltmarshes, the team identified opportunities to restore these coastal wetlands and enhance their potential for climate change mitigation for the future. To do this, the team highlighted three local scale management actions for each Council, and mapped the restoration potential and benefits of each. The three actions, which are scalable to have widespread impact, included:
- Tidal reinstatement – potential to restore 441 ha and drawdown of ~3,208 tonnes CO2e yr−1
- Fencing – potential to restore 321 ha and drawdown ~2341 CO2e yr−1
- Managed retreat to sea-level rise – potential to restore over 9000 ha and drawdown >65,000 tonnes CO2e yr−1
To implement these actions, the Blue Carbon Lab team developed a ‘Blue Carbon Roadmap’, which proposes a range of activities for the future management of blue carbon in the region. The Roadmap proposes activities to advance research, engage communities, improve governance, enable finance and kick start local conservation and restoration projects.
The findings of the project are a great example of how local scale management of our coastal wetlands can have widespread impacts, with the potential to play a huge role in climate change adaptation and mitigation in the future. All findings and recommendations can be found in the report Blue carbon opportunities at a local scale within Western Port Bay & eastern Port Phillip Bay.