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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 13, issue 15
Biogeosciences, 13, 4581-4594, 2016
https://doi.org/10.5194/bg-13-4581-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 4581-4594, 2016
https://doi.org/10.5194/bg-13-4581-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 15 Aug 2016

Research article | 15 Aug 2016

Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

Oscar Serrano1,2, Aurora M. Ricart1,3, Paul S. Lavery1,4, Miguel Angel Mateo1,4, Ariane Arias-Ortiz5, Pere Masque1,2,5,6, Mohammad Rozaimi1,7, Andy Steven8, and Carlos M. Duarte9 Oscar Serrano et al.
  • 1School of Sciences, Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup WA 6027, Australia
  • 2The University of Western Australia Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
  • 3Departament d'Ecologia, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
  • 4Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones Científicas, 17300 Blanes, Spain
  • 5Departament de Física & Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain
  • 6School of Physics, the University of Western Australia, Crawley WA 6009, Australia
  • 7School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
  • 8CSIRO, EcoSciences Precinct, 41 Boggo Road, Dutton Park QLD 4102, Australia
  • 9Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia

Abstract. Biotic and abiotic factors influence the accumulation of organic carbon (Corg) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2–4m depth) accumulated 3- to 4-fold higher Corg stocks (averaging 6.3kgCorgm−2) at 3- to 4-fold higher rates (12.8gCorgm−2yr−1) compared to meadows closer to the deep limits of distribution (at 6–8m depth; 1.8kgCorgm−2 and 3.6gCorgm−2yr−1). In shallower meadows, Corg stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (<0.125mm) in shallower meadows (2.0mmyr−1 and 9%, respectively) were approximately 2-fold higher than in deeper meadows (1.2mmyr−1 and 5%, respectively). The Corg stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6kgCorgm−2 and 1.2gCorgm−2yr−1) were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1%) and seagrass detritus contribution to the Corg pool (20%) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

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The recent focus on carbon (C) trading has intensified interest in "Blue Carbon" – C sequestered by coastal vegetation. However, the factors influencing C storage are poorly understood. The patterns found in this study support that C storage in Posidonia seagrass soils is influenced by interactions of biological, chemical and physical factors within the meadow. We conclude that there is a need to improve global estimates accounting for biogeochemical factors driving variability within habitats.
The recent focus on carbon (C) trading has intensified interest in "Blue Carbon" – C...
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