Communication

Seagrass meadows store twice as much carbon as forests, according to IMEDEA (CSIC-UIB) researchers

  • An international research team presents the first global analysis about carbon storage in these meadows
  • Although the meadows occupy less than 0.2% of the ocean surface they are in charge of burying more than 10% of the entire amount of carbon absorbed annually by the oceans

Madrid, 28th May 2012. An international research team, involving the Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB), has found that seagrass meadows can store twice as much carbon as temperate and tropical forests. The study, published in the latest issue of the journal Nature Geoscience, confirms the relevant role these ecosystems play mitigating the effects of climate change.

The study presents the first global analysis about carbon storage in these meadows after compiling 3,640 estimations for the amount of carbon stored on the ground and biomass of 946 seagrass meadows spread across the planet. The study shows that plants surroundings costs can bury up to 830 tons of carbon per ha. on the ground that harbor below. A tropical forest, in contrast, has the ability to store, on average, about 300 tons per ha.

Seagrass meadows are one of the most threatened ecosystems on the planet.

According to scientists, it is estimated that more than a quarter of its global extension has been destroyed. This is mainly due to the eutrophication of the coast and the sea floor dredging, which cause the acceleration of the overall loss rate. The meadows can accumulate in its grounds deposits of organic carbon more than one meter thick. In some species such as Posidonia oceanica on the Mediterranean Sea, the thickness of these deposits can be up to over four meters”, says Óscar Serrano, CSIC researcher at the Center for Advanced Studies of Blanes.

The researchers also calculated that although the meadows occupy less than 0.2% of the ocean surface they are in charge of burying more than 10% of the entire amount of carbon absorbed annually by the oceans. According to the study, these ecosystems accumulate 90% of the carbon they have on the ground where they grow up and, unlike forests, continue to do so indefinitely while sea level raises.

According to the CSIC researcher Carlos Duarte, “the great capacity of grasslands as sinks is based on the fact that this ecosystem fixes more carbon than it consumes or breathes, the fact that part of the net ecosystem production is buried, as well as the fact that they trap and bury particles of the water column. In contrast to forest floors, sediment in the seagrass meadows accumulates vertically as sea level rises and therefore can increase their volume over centuries and millennia.

 The absence of fire at sea also contributes to the persistence of these carbon sinks”, notes Duarte. “The organic carbon deposits result from accumulation over centuries and millennia”, says Miguel Ángel Mateo, CSIC researcher at the Center for Advanced Studies of Blanes. In particular, it is in the posidonia meadows in the Mediterranean Sea where this research has found the highest concentration of carbon.

To these scientists, the results show that “it is essential to conserve and restore seagrass meadows to preserve their capacity as a sink for CO2”. Their conservation, next to that of mangroves and marshes, help to mitigate climate change impacts, while preserving the benefits to society.

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Source: Dpto. Comunicación CSIC.

Citation: James W. Fourqurean, Carlos M. Duarte, Hilary Kennedy, Núria Marbà, Marianne Holmer, Miguel Ángel Mateo, Eugenia T. Apostolaki, Gary A. Kendrick, Dorte Krause?Jensen, Karen J. Mc Glatheryand, Óscar Serrano. Seagrass ecosystems as a globally significant carbon stock. Nature Geoscience. DOI:10.1038/Ngeo1477.