Seagrass Stores More Carbon Than Forests

Tuesday, 22 May 2012 Reuters

Seagrass meadows store 90 per cent of their carbon in the soil and continue to build on this indefinitely

Coastal seagrass can store more heat-trapping carbon per square kilometre than forests can, which means these coastal plants could be part of the solution to climate change.

Even though seagrasses occupy less than 0.2 per cent of the world's oceans, they can hold up to 83,000 tonne of carbon per square kilometre, a global team of researchers reported in the journal Nature Geoscience.

That is more than twice the 30,000 tonnes of carbon per square kilometre a typical terrestrial forest can store.

Earth's oceans are an important carbon sink, keeping climate-warming carbon dioxide from human-made and natural sources out of the atmosphere. The scientists found that seagrasses account for more than 10 per cent of all the carbon buried in oceans, also known as blue carbon.

The study included researchers from the United States, Spain, Australia, the United Kingdom, Denmark and Greece.

The greatest concentration of carbon found was in the Mediterranean where seagrass meadows stored carbon many metres deep. According to the study, seagrass meadows store 90 per cent of their carbon in the soil and continue to build on this indefinitely.

"These results show that seagrasses are key sites for carbon storage and probably are far more important as carbon dioxide sinks than we realised," says study co-author Professor Gary Kendrick of the University of Western Australia.

In addition to storing carbon, seagrasses filter out sediment before it gets into oceans, protect coastlines from floods and storms and serve as habitat for fish, crustaceans and other commercially important species.

Seagrasses can be damaged by human activity, such as pollution from oil spills and by boat propellers and cargo that can rake through seagrass meadows and cut through roots.

"The good news is if seagrass meadows are restored they can effectively and rapidly re-establish lost carbon sinks and stores, as well as providing a range of other valuable ecosystem benefits, including water quality protection, and as an important biodiversity habitat," says Kendrick.

Some of the study's authors are affiliated with the Blue Carbon Initiative, a global plan to mitigate climate change by conserving and restoring coastal marine ecosystems. The initiative is a collaboration between UNESCO, the International Union for Conservation of Nature and Conservation International.

Source: ABC Science News