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Seagrass meadows for climate change: Why Blue Carbon is a critical part of the greenhouse gas story


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Seagrass Meadows and Climate Change

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We are all aware of the importance of diverse ecosystems to the health of

the planet. We often hear about forests and their role in the fight against climate change. Forests are huge reservoirs of carbon globally and critical to the mitigation of greenhouse gasses in the atmosphere. A lesser-known natural reservoir and potential greenhouse gas sink is what is known as seagrass meadows. These reservoirs are part of a larger group of aquatic plants that have the ability to sequester carbon known as Blue Carbon. In this article we will have a look at the importance of seagrasses and their carbon reservoirs and why it’s critical that we understand their role and work to protect them.


The declines in seagrasses globally over the last several decades is a little-known issue that requires understanding and awareness so that we can all work to protect these critical ecosystems. Additionally, caution must be exercised with respect to Carbon Credits associated with Blue Carbon, as the actual carbon uptake by these diverse ecosystems can vary significantly.


What are Seagrasses?

Seagrasses — not to be confused with seaweed — are a unique group of

marine flowering plants usually growing in soft sediments of shallow estuaries where rivers meet the ocean. Among the types of seagrass is genera Zostera marina, commonly known as eelgrass and widely distributed along the Pacific Coast of Canada and the United States [21,30].

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These plants collectively create seagrass meadows—some of the planet's most productive and diverse ecosystems [7]. Seagrass meadows provide food and habitat for cod, herring, salmon, and other fish and invertebrates [6,32]. They provide coastal erosion protection, [12] food security for people,[18] sequester carbon, [7] and support commercial fisheries and subsistence fisheries that support entire communities [34]. The extent and rate of seagrass meadow loss can have significant economic, social, cultural, and ecological consequences. For example, the decline in seagrass presents a further threat to the endangered Chinook salmon [15,34].


With the decline in the seagrass meadows comes not only a decrease

in CO2 uptake from the air by the ocean, but the potential for CO2

release into the atmosphere from the carbon that has been stored in

the sediments [28] It is estimated that coastal seagrass beds store up to 83,000 metric tons of carbon per square kilometer, mostly in sediments. For comparison,

terrestrial forests store about 30,000 metric tons per square kilometer [37].


The Decline of Seagrass Meadows

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Despite the immense benefits of seagrasses, they are among the most globally threatened ecosystems, [27,34] incurring an annual global loss of approximately 0.4 to 2.6% [28] that since the beginning of the twentieth century it is estimated to have a total global loss of 29% [11]. To put this in perspective, it is estimated that last year deforestation on land was at a rate of approximately 0.2% per year globally. The loss of seagrass has been accredited to a broad spectrum of anthropogenic and natural causes, including: [14,27,34]

  • Coastal development (e.g., seawalls, dredging)

  • Destructive fishing practices

  • Marine traffic (e.g., boat propellors and anchors)

  • Sediment pollution

  • Disease

  • Non-native species

  • Climate change

How does Climate Change affect Seagrass Meadows?

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It is widely acknowledged that burning fossil fuels increases atmospheric CO2, which enhances the greenhouse gas effect, trapping more solar radiation and thus increasing global

temperatures. Approximately 80% of the excess heat is absorbed

by the ocean [7] which is concerning for seagrasses [31] as the temperature is generally the most crucial range-limiting factor. Thus, one of the most significant climate-related threats to

seagrass meadows and their associated carbon storage is increasing global temperatures that change the geographic range of seagrasses [7] accompanied by more frequent short-term marine heat waves [18] causing local or widespread seagrass dieoffs [25]. The warming temperatures also accelerate glacier melting and change precipitation patterns, which can affect the input and timing of particles, carbon, and nutrients discharged into the ocean[1]. This can reduce the amount of light available and smother

seagrass meadows [25].


How does Seagrass Meadow sequester carbon?

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Seagrasses are able to collect CO2 from the ocean – absorbed from the atmosphere and over time collect sediments high in carbon from both the oceans and the atmosphere.


Is Blue Carbon the Answer?

To address the effects of climate change, a dual strategy is necessary: an end to fossil fuel emissions and a mechanism to remove CO2 from the atmosphere. To remove CO2 from the atmosphere, various technologies have been proposed with varying degrees of uncertainties and risks. However, over the past decade, interest has developed in the sequestration of carbon in vegetated coastal ecosystems—known as Blue Carbon. These are seen as a low-risk, nature-based solution to offset carbon emissions because the global rate of sequestration in seagrass meadows has been estimated to be as much as 18% of the carbon sequestered in the sediment of the whole ocean [20] Although several projects have been created to offset emissions and provide carbon credits for sale based on Blue Carbon projects, we need to be cautious about how we quantify the true carbon uptake of these ecosystems.


Not all meadows are the same

Not all seagrass meadows have the same carbon sequestration and storage abilities. Different environmental factors determine the net organic carbon sequestration rate [18]. In the tropics and subtropics, large, long-lived species that produce extensive root mattes capable of storing large pools of organic carbon tend to dominate seagrass meadows [18]. Of the pools of organic carbon in living seagrasses, the largest was found in Mediterranean meadows dominated by Posidonia oceanica, a large seagrass with extensive, long-lived rhizomes11. In temperate waters, seagrasses tend to be smaller, short-lived, with short, fine roots 18, and thus may not store as much carbon as tropical meadows. Temperate meadows still contribute to carbon storage and could be used in climate change mitigation strategies. A single, consistent interpretation of the role of seagrass meadows in offsetting carbon emissions globally has yet to exist [18] We must be

extremely cautious making generalizations regarding blue carbon that have the potential to be counterproductive for tackling climate change [29] Interested readers can find a map showing the diversity in these ecosystems around the globe in this article: https://www.nature.com/articles/s41558-021-01089-4/figures/1


Final Thoughts

The preservation and restoration of seagrass meadows is an important piece of the overall Greenhouse Gas battle. These ecosystems are critical to marine life and biodiversity and are critical to the long-term sequestration of carbon.

Losing a seagrass meadow could represent the loss of thousands of years of carbon storage. Raising awareness about this precious ecosystem is vital if we are to actively protect and expand these natural carbon sequestration

machines. Nature has provided us with perfect carbon capture technology. Let’s ensure its survival so that we can reap the rewards of its many benefits to the earth.


References

1. Bidlack, A.L., Bisbing, S., Buma, B., Diefenderfer, H.L., et al. (2021) Climate-mediated changes to linked terrestrial and marine ecosystems across the northeast Pacific coastal temperate rainforest margin BioScience, 71(6), 581–95. doi:

10.1093/biosci/biaa171


2. Brouns, J.J. (1994). in Impacts of Climate Change on Ecosystems and Species: Marine and Coastal Ecosystems, eds Pernetta JC, Leemans R, Elder D, Humphrey S (International Union for Conservation of Nature, Gland, Switzerland), Vol 2, 59–72.


3. Campbell, C.R. (2010). Blue Carbon-British Columbia: The case for conserving and enhancing estuarine processes and sediments in B.C. B.C., Canada: Sierra Club. Available online: <http://sierraclub.bc.ca/wp-content/uploads/2015/08/Blue-Carbon-

British-Columbia -Report.pdf>.


4. CEC. (2016). North America’s Blue Carbon: Assessing Seagrass, Salt Marsh and Mangrove Distribution and Carbon Sinks. Montreal, Canada: Commission for Environmental Cooperation. 54pp. Available at: <www.cec.org/islandora/es/ item/11664-north-america-s-blue-carbon-assessing-seagrass-salt-marsh-and-mangrove>.


5. Chmura, G. L., Anisfeld, S. C., Cahoon, D. R. & Lynch, J. C. (2003). Global carbon sequestration in tidal, saline wetland soils. Glob. Biogeochem. Cycles, 17(4). doi: 10.1029/2002GB001917


6. Chung, I. K., Beardall, J., Mehta, S., Sahoo, D., and Stojkovic, S. (2011). Using marine macroalgae for carbon sequestration: a critical appraisal. J. Appl. Phycol., 23, 877–886. doi: 10.1007/s10811-010-9604-9


7. Duarte, B., Martins, I., Rosa, R., Matos, A.R., Roleda, M.Y., Reusch, T.B.H., Engelen, A.H., Serrão, E.A., Pearson, G.A., Marques, J.C., Caçador, I., Duarte, C.M. & Jueterbock, A. (2018). Climate Change Impacts on Seagrass Meadows and Macroalgal

Forests: An Integrative Perspective on Acclimation and Adaptation Potential. Front. Mar. Sci, 5(90). doi: 10.3389/fmars.2018.00190


8. Duarte, C. M., Kennedy, H., Marbà, N. & Hendriks, I. (2011). Assessing the capacity of seagrass meadows for carbon burial: Current limitations and future strategies. Ocean Coast. Manage. 51, 1-7. https://imedea.uibcsic.es/master/cambioglobal/Modulo_III_cod101608/tema%201-caracteristicas,funciones,servicios/Duarte%20et%20al%202011%20(ocean%26coastal%20management).pdf


9. Duffy, J.E., Richardson, J.P., & France, K. (2005). Ecosystem consequences of diversity depend on food chain length in estuarine vegetation. Ecol Lett, 8(3), 301–309. doi: 10.1111/j.1461-0248.2005.00725.x


10. Duffy, J.E. (2006). Biodiversity and the functioning of seagrass ecosystems. Mar Ecol Prog Ser, 311, 233-250. doi: 10.3354/meps311233


11. Fourqurean, J., Duarte, C., Kennedy, H., Marba, N., Holmer, M., Mateo, M., Apostolaki, E., Kendrick, G. Krause-Jensen, D., McGlathery, K., & Serrano, O. (2012). Seagrass ecosystems as a significant global carbon stock. Nature Geoscience, 5, 505-509.

doi: 10.1038/ngeo1477.


12. Harley, C. D. G., Anderson, K. M., Demes, K. W., Jorve, J. P., Kordas, R. L., Coyle, T. A., et al. (2012). Effects of climate change on global seaweed communities. J. Phycol. 48, 1064–1078. doi: 10.1111/j.1529-8817.2012.01224.x


13. Hendriks, I. E., Sintes, T., Bouma, T. & Duarte, C. M. (2007). Experimental assessment and modeling evaluation of the effects of seagrass (P. oceanica) on flow and particle trapping. Mar. Ecol. Prog. Ser., 356, 163–173. doi: 10.3354/meps07316


14. Howarth R., Anderson, D.M., Cloern, J.E., et al. (2000). Nutrient pollution of coastal rivers, bays and seas. Issues in Ecology, 7, 1–14.


15. Hughes, A.R., Williams, S.L., Duarte, C.M., Heck, K.L., & Waycott, M. (2009). Associations of concern: Declining seagrasses and threatened dependent species. Frontiers in Ecology and the Environment, 7(5), 242–246. Doi: 10.1890/080041


16. IPCC. (2018). Summary for policymakers Global Warming of 1.5 ◦C. An IPCC Special Report on the Impacts of Global Warming of 1.5 ◦C Above Pre-Industrial Levels and Related Global Greenhouse Gas Emission Pathways, in the Context of

Strengthening the Global Response to the Threat of Climate Change, Sustainable Development, and Efforts to Eradicate Poverty. https://www.ipcc.ch/sr15/


17. Jackson JBC, et al. (2001). Historical overfishing and the recent collapse of coastal ecosystems. Science, 293, 629–638. doi: 10.1126/science.1059199


18. Johannesen, S.C. (2022). How can blue carbon burial in seagrass meadows increase long-term, net sequestration of carbon? A critical review. Environ. Res. Lett. 17 093004. DOI 10.1088/1748-9326/ac8ab4


19. Keller, C. F. (2009). Global warming: a review of this mostly settled issue. Stoch. Environ. Res. Risk Assess., 23, 643–676. doi: 10.1007/s00477-008-0253-3


20. Kennedy, H., Beggins, J., Duarte, C.M., Fourqurean, J.W., Holmer, M., Marbà, N., & Middelburg, J.J. (2010). Seagrass sediments as a global carbon sink: isotopic constraints. Glob. Biogeochem. Cycles, 24, GB4026. doi: 10.1029/2010GB003848.


21. Lavery, P.S., Mateo, M.A., Serrano, O., & Rozaimi, M. (2013). Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service. PLoS ONE, 8(9). doi: 10.1371/journal.pone.0073748


22. Macreadie, P.I., Trevathan-Tackett, M., Skilbeck, C.G., Sanderman, J., et al. (2015). Losses and recovery of organic carbon from a seagrass ecosystem following disturbance Proc. R. Soc. B, 282(1817). doi: 10.1098/rspb.2015.1537


23. Mateo, M. A., Romero, J., Pérez, M., Littler, M. M. & Littler, D. S. (1997). Dynamics of millenary organic deposits resulting from the growth of the Mediterranean seagrass Posidonia oceanica. Estuar. Coast. Shelf Sci., 44, 103–110. doi:10.1006/ecss.1996.0116


24. Mcleod, E., Chmura, G.L., Bouillon, S., Salm, R., et al. (2011). 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. doi: 10.1890/110004


25. Murphy, G.E., Dunic, J., Ada,czyk, E.M., Bittick, S.J., et al. (2021). From coast to coast to coast: ecology and management of seagrass ecosystems across. Canada Facets, 6(1), 139–79. doi: 10.1139/facets-2020-0020


26. Oliver, E.C., Burrows, M.T., Donat, M.G., Gupta, A.S., et al. (2019). Projected marine heatwaves in the 21st century and the potential for ecological impact. Front. Mar. Sci., 6. doi: 10.3389/fmars.2019.00734


27. Orth, R.J., T.J.B. Carruthers, W.C. Dennison, C.M. Duarte, J., et al. (2006). A global crisis for seagrass ecosystems. BioScience, 56(12), 987–996. doi: 10.1641/0006-3568(2006)56[987:AGCFSE]2.0.CO;2


28. Pendleton, L., D.C. Donato, B. Murray, S. Crooks, W.A. Jenkins, S. Sifleet, & A. Baldera. (2012). Estimating global “blue carbon” emissions from conversion and degradation of vegetated coastal ecosystems. PLoS ONE, 7(9). doi:10.1371/journal.pone.0043542


29. Postlethwaite, V.R., McGowan, A.E., Kohfeld, K.E., Robinson, C.L.K., & Pellatt, M.G. (2018). Low blue carbon storage in eelgrass (Zostera marina) meadows on the Pacific Coast of Canada. PLoS ONE, 13(6). doi: 10.1371/ journal.pone.0198348


30. Raposa, K. & Bradley, M. (2009). Methods and protocols for eelgrass mapping in Rhode Island: recommendations from the Rhode Island eelgrass mapping task force. Narragansett Bay (RI): Narragansett Bay Research Reserve. Report No.:


31. Short, F., Carruthers, T., Dennison, W., and Waycott, M. (2007). Global seagrass distribution and diversity: a bioregional model. J. Exp. Mar. Bio. Ecol., 350, 3–20. doi: 10.1016/j.jembe.2007.06.012


32. Thomson, J. A., Burkholder, D. A., Heithaus, M. R., Fourqurean, J. W., Fraser, M. W., Statton, J., et al. (2015). Extreme temperatures, foundation species , and abrupt ecosystem change : an example from an iconic seagrass ecosystem. Glob.

Change Biol., 21, 1463–1474. doi: 10.1111/gcb.12694


33. Tutin, T.G. (1942). Zostera L. The Journal of Ecology, 30(1), 217–226. doi: 10.2307/2256698


34. Waycott, M., Duarte, C., Carruthers, T., Orth, R., et al. (2009). Accelerating loss of seagrass across the globe threatens coastal ecosystems. Proceedings of the National Academy of Sciences of the United States of America, 106, 12377-81. doi:

10.1073/pnas.0905620106.


35. Williams, S.L. (2007). Introduced species in seagrass ecosystems: Status and concerns. J Exp Mar Biol Ecol, 350(1), 89–110. doi: 10.1016/j.jembe.2007.05.032




Contributors


Researchers

Katarina Duke

Mauro Aiello, Ph.D.


Authors

Katarina Duke

Denis Koshelev

Mauro Aiello, Ph.D.


Lark Scientific Financial Support

Axel Doerwald


Graphics

Adri Poggetti


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