Expanding Greenland seagrass meadows contribute new sediment carbon sinks

Abstract
The loss of natural carbon sinks, such as seagrass meadows, contributes to grenhouse gas emissions and, thus, global warming. Whereas seagrass meadows are declining in temperate and tropical regions, they are expected to expand into the Arctic with future warming. Using paleoreconstruction of carbon burial and sources of organic carbon to shallow coastal sediments of three Greenland seagrass (Zostera marina) meadows of contrasting density and age, we test the hypothesis that Arctic seagrass meadows are expanding along with the associated sediment carbon sinks. We show that sediments accreted before 1900 were highly 13C depleted, indicative of low inputs of seagrass carbon, whereas from 1940’s to present carbon burial rates increased greatly and sediment carbon stocks were largely enriched with seagrass material. Currently, the increase of seagrass carbon inputs to sediments of lush and dense meadows (Kapisillit and Ameralik) was 2.6 fold larger than that of sparse meadows with low biomass (Kobbefjord). Our results demonstrate an increasing important role of Arctic seagrass meadows in supporting sediment carbon sinks, likely to be enhanced with future Arctic warming.

Citation
Marbà N, Krause-Jensen D, Masqué P, Duarte CM (2018) Expanding Greenland seagrass meadows contribute new sediment carbon sinks. Scientific Reports 8. Available: http://dx.doi.org/10.1038/s41598-018-32249-w.

Acknowledgements
This work was funded by EU FP7 (project Opera’s, contract number 308393) and King Abdullah University of Science and Technology (KAUST). DKJ received support from the COCOA project under the BONUS program funded by the EU 7th framework program and the Danish Research Council and from the NOVAGRASS (0603-00003DSF) project funded by the Danish Council for Strategic Research. P.M. was supported by the Generalitat de Catalunya through its grant 2017 SGR-1588. We are grateful to the Greenland Institute of Natural Resources for serving as logistic platform and we direct a special thanks to Flemming Heinrich, for help in the field. Kitte Linding Gerlich and Karina Bomholt Oest, Aarhus University, are thanked for help with laboratory analyses. The study is also a contribution to the Greenland Ecosystem Monitoring program (www.G-E-M.dk), the Arctic Science Partnership (www.asp-net.org) and the ICTA ‘Unit of Excellence’ (MinECo, MDM2015-0552)”.

Publisher
Springer Nature

Journal
Scientific Reports

DOI
10.1038/s41598-018-32249-w

Additional Links
https://www.nature.com/articles/s41598-018-32249-w

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