FCE researchers have found that seagrass ecosystems remove significant amounts of carbon dioxide from the atmosphere and store it in below-ground soils. If seagrass ecosystems continue to be lost due to nutrient enrichment, coastline modifications and sea level rise, a globally significant amount of carbon could be lost to the atmosphere.
- Key Findings
The protection of organic carbon stored in forests is considered as an important method for mitigating climate change. Like terrestrial ecosystems, coastal ecosystems store large amounts of carbon, and there are initiatives to protect these 'blue carbon' stores. Organic carbon stocks in tidal salt marshes and mangroves have been estimated, but uncertainties in the stores of seagrass meadows - some of the most productive ecosystems on Earth - hinder the application of marine carbon conservation schemes.
Jim Fourqurean dives near Shark Bay to research the extensive seagrass meadows. Credit: Dr. Gary Kendrick A team of international seagrass researchers, led by the FCE and VCR LTERs, compiled published and unpublished measurements of the organic carbon content of living seagrass biomass and underlying soils in 946 distinct seagrass meadows across the globe. Using only data from sites for which full inventories exist, they estimated that, globally, seagrass ecosystems could store as much as 19.9 Pg organic carbon. According to a more conservative approach that incorporates more data from surface soils and depth-dependent declines in soil carbon stocks, they estimated that the seagrass carbon pool lies between 4.2 and 8.4 Pg carbon. This means that the present rates of seagrass loss could result in the release of up to 299 Tg carbon per year, assuming that all of the organic carbon in seagrass biomass and the top meter of soils is remineralized.
- Results
A comparison of seagrass soil Corg> storage in the top meter of the soil with total ecosystem C>org storage for major forest types. Credit: Fourqurean, J.W., C.M. Duarte, H. Kennedy, N. Marba, M. Holmer, M.A. Mateo, E.T. Apostolaki, G.A. Kendrick, D. Krause-Jensen, K.J. McGlathery, O. Serrano. 2012. Seagrass ecosystems as a globally significant carbon stock. Nature Geoscience 5: 505-509. DOI: 10.1038/ngeo1477.
For more information, contact James Fourqurean.