Journal article
Does hydrogenotrophic methanogenesis occur in seagrass beds? Insights from whole-ecosystem stable isotope labelling
Environmental research letters, Vol.21(14), pp.1-27
22/07/2026
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Abstract
Seagrass beds are blue carbon ecosystems; however, they release methane (CH<sub>4</sub> ), a potent greenhouse gas. Although likely important, the influence of primary production on methanogenic pathways remains understudied. We labelled intact seagrass-sediment cores and in situ seagrass beds with 13 C-dissolved inorganic carbon ( <sup>13</sup> C-DIC) to trace the transfer to <sup>13</sup> C-CH<sub>4</sub> over a short (<24 hours) and long (35 days) time frame. Labelled carbon was transferred from DIC to CH<sub>4</sub> in the absence of primary production, indicating hydrogenotrophic methanogenesis or mixotrophy. Longer-term persistent in situ <sup>13</sup> C-CH<sub>4</sub> release suggests that CH<sub>4</sub> was also produced from <sup>13</sup> C-labelled organic substrates. The transformation rate of <sup>13</sup> C-DIC to 13 C-CH<sub>4</sub> was reduced by 50% in the light, indicating interactions with primary production via CH<sub>4</sub> oxidation, oxidative stress, or substrate competition. Additionally, dark CH<sub>4</sub> fluxes (5.1 ± 0.7 μmol m -2 d -1 ) were 16% higher than light CH<sub>4</sub> fluxes (4.3 ± 0.4 μmol m -2 d -1 ) in seagrass beds under in situ conditions. These findings highlight the role of plant-sediment interactions in governing methanogenic pathways, with implications for seagrass beds as carbon-sequestering hotspots and CH<sub>4</sub> sources.
Details
- Title
- Does hydrogenotrophic methanogenesis occur in seagrass beds? Insights from whole-ecosystem stable isotope labelling
- Creators
- Mona Abouhaidar Andskog - Southern Cross UniversityAna Sierra Padilla - Southern Cross UniversityTijs Joling - Southern Cross UniversityDamien T Maher - Southern Cross UniversityJames Z. Sippo - Southern Cross UniversityJack Middelburg - Utrecht UniversityBradley D. Eyre - Southern Cross UniversityJoanne M Oakes - Southern Cross University
- Publication Details
- Environmental research letters, Vol.21(14), pp.1-27
- Publisher
- IOP Publishing Ltd; Bristol
- Grant note
- This research was supported by the Australian Research Council Discovery Project DP200100546, which provided project funding and PhD stipends, and by an Australian Institute of Nuclear Science and Engineering Postgraduate Research Award (AINSE PGRA).
- Identifiers
- 991013389926302368
- Copyright
- © 2026 The Author(s).
- Academic Unit
- Faculty of Science and Engineering; Graduate School; Science
- Language
- English
- Resource Type
- Journal article