Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Seagrass ecosystems as a globally significant carbon stock


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. Here, we compile published and unpublished measurements of the organic carbon content of living seagrass biomass and underlying soils in 946 distinct seagrass meadows across the globe.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, we estimate that, globally, seagrass ecosystems could store as much as 19.9 Pg organic carbon; according to a more conservative approach, in which we incorporate more data from surface soils and depth-dependent declines in soil carbon stocks, we estimate that the seagrass carbon pool lies between 4.2 and 8.4 Pg carbon. We estimate that 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 metre of soils is remineralized.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Mediterranean seagrass meadows of P. oceanica have the largest documented Corg stores, which can form ‘mattes’ of high Corg content not reported for other seagrass species.
Figure 2
Figure 3: Frequency distribution of reported and calculated observations of soil Corg from seagrass meadows.
Figure 4: Frequency histogram of estimates of soil Corg stored in the world’s seagrass meadows.
Figure 5: A comparison of seagrass soil Corg storage in the top metre of the soil with total ecosystem Corg storage for major forest types.


  1. Forster, P. et al. in IPCC Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) (Cambridge Univ. Press, 2007).

    Google Scholar 

  2. Agrawal, A., Nepstad, D. & Chhatre, A. Reducing emissions from deforestation and forest degradation. Ann. Rev. Environ. Resour. 36, 373–396 (2011).

    Article  Google Scholar 

  3. IPCC Good Practice Guidance for Land Use, Land-Use Change and Forestry (IPCC National Greenhouse Gas Inventories Programme, 2003).

  4. IPCC Climate Change 2007: Synthesis Report 104 (IPCC, 2007).

  5. Keith, H., Mackey, B. G. & Lindenmayer, D. B. Re-evaluation of forest biomass carbon stocks and lessons from the world’s most carbon-dense forests. Proc. Natl. Acad. Sci. USA 106, 11635–11640 (2009).

    Article  Google Scholar 

  6. Chmura, G. L., Anisfeld, S. C., Cahoon, D. R. & Lynch, J. C. Global carbon sequestration in tidal, saline wetland soils. Glob. Biogeochem. Cycles 17, 1111 (2003).

    Article  Google Scholar 

  7. Donato, D. C. et al. Mangroves among the most carbon-rich forests in the tropics. Nature Geosci. 4, 293–297 (2011).

    Article  Google Scholar 

  8. Duarte, C. M., Middelburg, J. J. & Caraco, N. Major role of marine vegetation on the oceanic carbon cycle. Biogeosciences 2, 1–8 (2005).

    Article  Google Scholar 

  9. Mcleod, E. et al. A blueprint for blue carbon: Toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2 . Front. Ecol. Environ 7, 362–370 (2011).

    Article  Google Scholar 

  10. Duarte, C. M. & Chiscano, C. L. Seagrass biomass and production: A reassessment. Aquat. Bot. 65, 159–174 (1999).

    Article  Google Scholar 

  11. Zieman, J. C. & Wetzel, R. G. in Handbook of Seagrass Biology, An Ecosystem Prospective (eds Phillips, R. C. & McRoy, C. P.) 87–116 (Garland STPMPress, 1980).

    Google Scholar 

  12. Kennedy, H. et al. Seagrass sediments as a global carbon sink: Isotopic constraints. Glob. Biogeochem. Cycles 24, GB4026 (2010).

    Article  Google Scholar 

  13. Mateo, M. A., Cebrián, J., Dunton, K. & Mutchler, T. in Seagrasses: Biology, Ecology and Conservation (eds Larkum, A. W. D., Orth, R. J. & Duarte, C. M.) 159–192 (Springer, 2006).

    Google Scholar 

  14. Mateo, M. A., Romero, J., Pérez, M., Littler, M. M. & Littler, D. S. Dynamics of millenary organic deposits resulting from the growth of the Mediterranean seagrass Posidonia oceanica. Estuar. Coast. Shelf Sci. 44, 103–110 (1997).

    Article  Google Scholar 

  15. Orem, W. H. et al. Geochemistry of Florida Bay sediments: Nutrient history at five sites in eastern and central Florida Bay. J. Coast. Res. 15, 1055–1071 (1999).

    Google Scholar 

  16. Serrano, O. et al. The Posidonia oceanica marine sedimentary record: A Holocene archive of heavy metal pollution. Sci. Total Environ. 409, 4831–4840 (2011).

    Article  Google Scholar 

  17. Smith, S. V. Marine macrophytes as a global carbon sink. Science 211, 838–840 (1981).

    Article  Google Scholar 

  18. Waycott, M. et al. Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proc. Nat. Acad. Sci. USA 106, 12377–12381 (2009).

    Article  Google Scholar 

  19. Orth, R. J. et al. A global crisis for seagrass ecosystems. BioScience 56, 987–996 (2006).

    Article  Google Scholar 

  20. IPCC in IPCC Guidelines for National Greenhouse Gas Inventories (eds H.S. Eggleston et al.) (National Greenhouse Gas Inventories Programme,IGES, 2006).

  21. Charpy-Roubaud, C. & Sournia, A. The comparative estimation of phytoplanktonic and microphytobenthic production in the oceans. Mar. Microb. Food Webs 4, 31–57 (1990).

    Google Scholar 

  22. Houghton, R. A. Balancing the global carbon budget. Ann. Rev. Earth Planet. Sci. 35, 313–347 (2007).

    Article  Google Scholar 

  23. Duarte, C. M., Kennedy, H., Marbà, N. & Hendriks, I. Assessing the capacity of seagrass meadows for carbon burial: Current limitations and future strategies. Ocean Coast. Manage. 51, 671–688 (2011).

    Google Scholar 

  24. Hendriks, I. E., Sintes, T., Bouma, T. & Duarte, C. M. Experimental assessment and modeling evaluation of the effects of seagrass (P. oceanica) on flow and particle trapping. Mar. Ecol. Prog. Ser. 356, 163–173 (2007).

    Article  Google Scholar 

  25. Lo Iacono, C. et al. Very high-resolution seismo-acoustic imaging of seagrass meadows (Mediterranean Sea): Implications for carbon sink estimates. Geophys. Res. Lett. 35, L18601 (2008).

    Article  Google Scholar 

  26. Short, F. T. & Wyllie-Echeverria, S. Natural and human-induced disturbance of seagrasses. Environ. Conserv. 23, 17–27 (1996).

    Article  Google Scholar 

  27. Duarte, C. M. et al. Seagrass community metabolism: Assessing the carbon sink capacity of seagrass meadows. Glob. Biogeochem. Cycles 24, GB4032 (2010).

    Article  Google Scholar 

  28. Jandl, R. et al. How strongly can forest management influence soil carbon sequestration? Geoderma 137, 253–268 (2007).

    Article  Google Scholar 

  29. Paul, K. I., Polglase, P. J., Nyakuengama, J. G. & Khanna, P. K. Change in soil carbon following afforestation. Forest Ecol. Manag 168, 241–257 (2002).

    Article  Google Scholar 

  30. Paling, E. I., Fonseca, M., van Katwilk, M. M. & Van Keulen, M. in Coastal Wetlands: An Integrated Ecosystem Approach (eds Perillo, M. E., Wolanski, E., Cahoon, D. R. & Brinson, M. M.) (Elsevier, 2009).

    Google Scholar 

  31. Duarte, C. M. The future of seagrass meadows. Environ. Conserv. 29, 192–206 (2002).

    Article  Google Scholar 

  32. Irving, A. D., Conell, S. D. & Russell, B. D. Restoring coastal plants to improve global carbon storage: Reaping what we sow. Plos One 6, e18311 (2011).

    Article  Google Scholar 

  33. Lawson, S. E., Wiberg, P. L., McGlathery, K. J. & Fugate, D. C. Wind-driven sediment suspension controls light availability in a shallow coastal lagoon. Estuar. Coasts 30, 102–112 (2007).

    Article  Google Scholar 

  34. Orth, R. J., Luckenbach, M. L., Marion, S. R., Moore, K. A. & Wilcox, D. J. Seagrass recovery in the Delmarva Coastal Bays, USA. Aquat. Bot. 84, 26–36 (2006).

    Article  Google Scholar 

  35. Orth, R. J., Moore, K. A., Marion, S. R., Wilcox, D. J. & Parrish, D. Seed addition facilitates Zostera marina L. (eelgrass) recovery in a coastal bay system (USA). Mar. Ecol. Prog. Ser. 448, 177–195 (2012).

    Article  Google Scholar 

  36. McGlathery, K. J. et al. Recovery trajectories during state change from bare sediment to eelgrass dominance. Mar. Ecol. Prog. Ser. 448, 209–221 (2012).

    Article  Google Scholar 

  37. Pedersen, M. F., Duarte, C. M. & Cebrián, J. Rates of change in organic matter and nutrient stocks during seagrass Cymodocea nodosa colonization and stand development. Mar. Ecol. Prog. Ser. 159, 29–36 (1997).

    Article  Google Scholar 

  38. Barrón, C., Marbà, N., Terrados, J., Kennedy, H. & Duarte, C. M. Community metabolism and carbon budget along a gradient of seagrass (Cymodocea nodosa) colonization. Limnol. Oceanogr. 49, 1642–1651 (2004).

    Article  Google Scholar 

  39. Nellemann, C. et al. Blue Carbon. A Rapid Response Assessment 78 (United Nations Environment Programme, GRID-Arenal, 2009).

  40. Duarte, C. M. Seagrass nutrient content. Mar. Ecol. Prog. Ser. 67, 201–207 (1990).

    Article  Google Scholar 

  41. Fourqurean, J. W., Marbà, N., Duarte, C. M., Diaz-Almela, E. & Ruiz-Halpern, S. Spatial and temporal variation in the elemental and stable isotopic content of the seagrasses Posidonia oceanica and Cymodocea nodosa from the Illes Balears, Spain. Mar. Biol. 151, 219–232 (2007).

    Article  Google Scholar 

  42. Fourqurean, J. W., Moore, T. O., Fry, B. & Hollibaugh, J. T. Spatial and temporal variation in C:N:P ratios, δ15N, and δ13C of eelgrass Zostera marina as indicators of ecosystem processes, Tomales Bay, California, USA. Mar. Ecol. Prog. Ser. 157, 147–157 (1997).

    Article  Google Scholar 

  43. Fourqurean, J. W., Zieman, J. C. & Powell, G. V. N. Phosphorus limitation of primary production in Florida Bay: Evidence from the C:N:P ratios of the dominant seagrass Thalassia testudinum. Limnol. Oceanogr. 37, 162–171 (1992).

    Article  Google Scholar 

  44. Hemminga, M. A. & Duarte, C. M. Seagrass Ecology (Cambridge Univ.Press, 2000).

    Book  Google Scholar 

Download references


This is a contribution of the International Blue Carbon Science Working Group. We thank the contributors of unpublished data to our database, including A. Paytan, W.H. Orem and M. Copertino. Partial support for J.W.F.’s contribution was provided by a Gledden Visiting Senior Fellowship from the Institute of Advanced Studies, University of Western Australia and an Australian National Network in Marine Sciences Visiting Scholar fellowship and by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research programme under Grant No. DBI-0620409. C.M.D and N.M. were financially supported through the MEDEICG project of the Spanish Ministry of Science and Innovation (project ID CTM2009-07013). G.A.K. was supported by NHT II- Caring for our Country funding. M.H. was financially supported by the Danish Natural Science Foundation (09-071369). M.A.M. and O.S. acknowledge the Spanish Ministry of Science and Innovation (MICINN) and the High Council of Scientific Research (CSIC) for financially supporting various pioneering projects to explore the role of P. oceanica as a coastal C sink and a palaeoecological record. D.K.J. acknowledges the Danish National Monitoring and Assessment Programme for the Aquatic and Terrestrial Environment (NOVANA) and colleagues associated with the programme for support. K.J.M. was supported by the National Science Foundation through the Virginia Coast Reserve Long-Term Ecological Research programme under Grant No. 0621014. This is contribution no. 550 from the Southeast Environmental Research Center at Florida International University.

Author information

Authors and Affiliations



All authors contributed extensively to the work presented in this paper.

Corresponding author

Correspondence to James W. Fourqurean.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 567 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fourqurean, J., Duarte, C., Kennedy, H. et al. Seagrass ecosystems as a globally significant carbon stock. Nature Geosci 5, 505–509 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing