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Mangrove forests play a major role pumping carbon the atmosphere the ocean, and may help regulate greenhouse gas concentrations. The trouble is, they are disappearing.

Mangroves are the intertidal forests that fringe many tropical coastlines. Like all plants, mangroves fix carbon dioxide the air photosynthesis and return organic material the soil when they decompose. But because their roots and soil are regularly washed tides, much of this organic carbon leaches the ocean.

Researchers led Thorsten Dittmar Florida State University in Tallahassee measured how much mangroves contribute the organic carbon dissolved ocean waters the coast of Brazil. They estimated that, worldwide, mangroves contribute a hefty 10 per cent the ocean's dissolved organic carbon .

This is roughly equal the amount entering the ocean from the Amazon river, the largest single source dissolved organic carbon. Much of the carbon produced mangroves is the form of molecules that are highly resistant decomposition, so it is likely to remain in the ocean decades instead being returned to the atmosphere as carbon dioxide.