Reducing greenhouse gas emissions is critical to limiting human-induced climate change. However, we also need other solutions to help drawdown excess carbon dioxide already in our atmosphere.
The Blue Carbon Seascapes project seeks to establish if tropical seaweeds could provide a nature-based solution to help reduce climate change effects.
The five-year project, co-funded by AIMS and BHP, will help answer fundamental questions in blue carbon science. While focused on tropical marine ecosystems in Australia’s north-west, the science will be transferrable across the tropical world where these seaweeds are commonly found.
What is blue carbon?
The oceans are thought to have more capacity than forests to regulate our climate. They do this thanks to their ability to capture and store carbon in vast areas of soil along our coasts and under our deep oceans. This blue carbon storage provides a buffer against the effects of climate change by locking the carbon away from the atmosphere.
A primary pathway for blue carbon storage is via the process of photosynthesis, whereby coastal plants like mangroves, saltmarsh and seagrass, and marine plants living in the ocean, draw in carbon dioxide from the air or water around them and incorporate this into their tissues. When those pieces of plant break off, some become buried in the soils around them, and in the deep sea, where it becomes stored for hundreds to thousands of years. This sequestered carbon is known as blue carbon.
One of the plants that could be driving this storage of blue carbon is a common tropical seaweed known as Sargassum, found across the world. In the Blue Carbon Seascapes project, AIMS scientists are collecting hard data on how much blue carbon flows from Sargassum into different coastal and deep ocean environments, how long it is stored there and how we can best protect and enhance this natural process.
Investigating a common tropical seaweed for blue carbon
AIMS scientists’ research has found that the natural seasonal cycles of Sargassum off the Western Australian coast incorporate significant amounts of carbon during their summer growth phase.
The key to understanding Sargassum’s contribution to blue carbon is held in these marine soils. To unlock this information, the science team are collecting soil cores (long, thin samples of the seabeds or muds underneath seagrass beds and mangrove forests) along the Ningaloo, Exmouth Gulf and Port Hedland coasts of Western Australia.
This natural pathway for carbon sequestration has been happening for millions of years. The Blue Carbon Seascapes project aims to work out how we best protect that natural process, and whether we can dial it up to help us drawdown some of the excess carbon dioxide in our atmosphere.
More about Sargassum
Sargassum is common in many shallow waters, particularly in the tropics.
Its large, complex canopy of golden brown are an important food and shelter for fish and small critters. At Ningaloo, Sargassum is especially important habitat for young Spangled emperor (Lethrinus nebulosos) who feed and grow in the Sargassum meadows until they become fully-grown adult fish. Spangled emperors support the majority of the local recreational fishery catch at Ningaloo.
If we find that Sargassum can be a solution to safely store carbon in our oceans, this project could provide a game-changing addition to our portfolio of solutions to climate change.
The five year $20m Blue Carbon Seascapes project is co-funded by AIMS and BHP and began in 2023.
Feature image: Violeta Brosig.
