Like terrestrial ecosystems, coastal ecosystems store large amounts of carbon, and there are initiatives to protect these ‘blue carbon’ stores.
Although seagrass meadows occupy less than 0.2 percent of the world's oceans, they are responsible for more than 10 percent of all carbon buried annually in the sea, according to a research paper published this week in the journal Nature Geoscience.
The paper, "Seagrass Ecosystems as a Globally Significant Carbon Stock," is the first global analysis of carbon stored in seagrasses.
The results demonstrate that coastal seagrass beds store up to 83,000 metric tons of carbon per square kilometer, mostly in the soils beneath them. As a comparison, a typical terrestrial forest stores about 30,000 metric tons per square kilometer, most of which is in the form of wood. Seagrass meadows, on the other hand, store ninety percent of their carbon in the soil--and continue to build on it for centuries.
In the Mediterranean, the geographic region with the greatest concentration of carbon found in the study, seagrass meadows store carbon in deposits many meters deep.
Seagrasses are among the world's most threatened ecosystems. Some 29 percent of all historic seagrass meadows have been destroyed, mainly due to dredging and degradation of water quality. At least 1.5 percent of Earth's seagrass meadows are lost every year.
One remarkable thing about seagrass meadows is that, if restored, they can effectively and rapidly sequester carbon and reestablish lost carbon sinks
Karen McGlathery, University of Virginia