A climate change research project is measuring the so called "blue" carbon stored in mangrove forest mud around Darwin harbour. The scientists hope the data they're gathering could help protect Southeast Asian coastal environments in years to come.
Source: 7.30 NT | Duration: 5min 20sec
DANIELLE PARRY, PRESENTER: It's been dubbed blue carbon. It's the carbon stored in marine ecosystems - such as mangrove forests and sea-grass beds. Now a climate-change research project is measuring how much carbon is stored in the mud around Darwin Harbour. Scientists hope the data they're gathering will help protect South East Asian coastal environments in years to come. Genevieve Hussey reports.
GENEVIEVE HUSSEY, REPORTER: In the mangrove forests around Darwin harbour scientists from Charles Darwin University are gathering hundreds of samples of mud. It's part of a cutting edge climate-change research project - measuring what's called blue carbon.
DR LINDSAY HUTLEY, ENVIRONMENTAL SCIENCE, CHARLES DARWIN UNIVERSITY: It's a bit of a new term. But it's carbon stored in marine ecosystems the ocean and also the coastal systems like mangroves, sea grasses, salt marshes - things like that.
GENEVIEVE HUSSEY: Researchers want to know how much carbon is stored within marine ecosystems. That information can be used to work out what impact the protection or destruction of these areas has on climate change. Early research worldwide indicates blue carbon is vitally important.
DR KEITH MCGUINESS ECOLOGIST, CHARLES DARWIN UNIVERSITY: They are highly productive ecosystems. We're starting to get a handle on just how productive they are and the figures that are coming out are quite surprising, but they are often more productive than tropical rainforest systems and that's something that people find very, very surprising.
DR LINDSAY HUTLEY, ENVIRONMENTAL SCIENCE, CHARLES DARWIN UNIVERSITY: Blue carbon ecosystems store quite a lot more carbon per area, per land unit area than many terrestrial ecosystems, forests, et cetera.
GENEVIEVE HUSSEY: CDU honours student Le Bai has taken on the task of collecting the mud samples from Darwin's mangrove forests to find out how much carbon is stored in mangrove soils. He's using a steel pump to suck up the soil from a metre underground, and collecting samples from a range of sites across the 20,000 hectares that make up the mangrove reserve.
LE BAI, HONOURS STUDENT: We are going to select 15 sites across Darwin harbour and we are going to take soil samples from these 15 sites. We are doing five replications so the equipment we are using is called a piston sampler, where we could push the whole thing into the mud and we suck at least one metre, sort of two, soils into this cylinder.
GENEVIEVE HUSSEY: Darwin is an ideal location for the research because of the relatively pristine nature of the mangroves. Only about two percent of Darwin's mangroves have been disturbed in any serious way by human activity.
DR KEITH MCGUINESS ECOLOGIST, CHARLES DARWIN UNIVERSITY: It's a large and very significant stand of mangroves within the context of Australia and also world mangrove reserves. 20,000 hectares in one location is a large, large forest.
GENEVIEVE HUSSEY: Back at the laboratory the soil samples are ground and sieved to remove roots and stones. The powdered mud is then analysed to find out just how much carbon is stored within it. Scientists say the data will fill a gap in our knowledge.
DR KEITH MCGUINESS ECOLOGIST, CHARLES DARWIN UNIVERSITY: Now we actually have estimates of the trees. The biomass, the litter that falls down - that's the leaves and branches and the one big box that we don't know anything much about is what is actually stored in the soil itself, and that is often a huge amount of carbon.
GENEVIEVE HUSSEY: Heavily developed coastal environments in South East Asia could eventually benefit from the Darwin-based research. The scientists say this data will help them estimate how much carbon is released when mangrove forests are destroyed.
LE BAI, HONOURS STUDENT: Once the mangrove forests get cleared within eight years of time 50 percent of carbon reduction and these carbons have been released into the atmosphere where otherwise has been stored more than 10,000 years.
GENEVIEVE HUSSEY: The data will also help in developing estimates of the positive impact on greenhouse gas emissions of mangrove forest rehabilitation.
DR LINDSAY HUTLEY, ENVIRONMENTAL SCIENCE, CHARLES DARWIN UNIVERSITY: A lot of the South East Asian ecosystems are degraded - they might effectively be leaking carbon, they've been cleared - they've been cleared for aquaculture perhaps, they might have be used for fuel woods, they've been burnt even. Our data would let people know what is possible to be stored or what is stored in these ecosystems when they are in an intact state.
DR KEITH MCGUINESS ECOLOGIST, CHARLES DARWIN UNIVERSITY: In South East Asian areas in general, mangrove forests and other unusual coastal systems like sea grasses are under huge stresses from development, from harvesting and so on, and if we can find ways to make those resources more valuable as intact forests and sea-grass beds then there's more incentive to keep them, preserve them, manage them effectively.
GENEVIEVE HUSSEY: By the end of this year the research around Darwin harbour will be complete. Scientists hope the information they're gathering now will help guide development for years to come.