Abstract
Coastal zones account for 75% of marine methane emissions, despite covering only 15% of the ocean surface area. In these ecosystems, the tight balance between methane production and oxidation in sediments prevents most methane from escaping into seawater. However, anthropogenic activities could disrupt this balance, leading to an increased methane escape from coastal sediments. To quantify and unravel potential mechanisms underlying this disruption, we used a suite of biogeochemical and microbiological analyses to investigate the impact of anthropogenically induced redox shifts on methane cycling in sediments from three sites with contrasting bottom water redox conditions (oxic-hypoxic-euxinic) in the eutrophic Stockholm Archipelago. Our results indicate that the methane production potential increased under hypoxia and euxinia, while anaerobic oxidation of methane was disrupted under euxinia. Experimental, genomic, and biogeochemical data suggest that the virtual disappearance of methane-oxidizing archaea at the euxinic site occurred due to sulfide toxicity. This could explain a near 7-fold increase in the extent of escape of benthic methane at the euxinic site relative to the hypoxic one. In conclusion, these insights reveal how the development of euxinia could disrupt the coastal methane biofilter, potentially leading to increased methane emissions from coastal zones.
Original language | English |
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Pages (from-to) | 11421-11435 |
Number of pages | 15 |
Journal | Environmental Science and Technology |
Volume | 58 |
Issue number | 26 |
DOIs | |
Publication status | Published - 2 Jul 2024 |
Bibliographical note
Publisher Copyright:© 2024 The Authors. Published by American Chemical Society.
Funding
We thank the captain, the crew of RV Electra, and Christoph Humborg for their assistance with the fieldwork. Arnold van Dijk, Coen Mulder, Helen de Waard, Tom Bastiaan, and Liam Kirwan (Utrecht University) are thanked for analytical assistance. This study was funded by ERC Synergy MARIX 854088 (M.S.M.J., C.P.S., and N.A.G.M.v.H.), NESCC 02001001 (W.K.L., A.J.W., M.S.M.J., and C.P.S.), SIAM 024002002 (M.J.E.M., C.U.W., M.S.M.J.), Havsochvattenmyndigheten DNR 1960-2018 (M.H. and C.P.S.), VI.Veni.222.332 (W.K.L.), and VI.Veni.212.040 (P.D.M.). We are also grateful to Rasmus Rodineliussen for assistance with sampling, Linnea Kop for ideas and code for data visualization, and Mike Lee for creating the DADA2 tutorial (https://astrobiomike.github.io/amplicon/dada2_workflow_ex) from which we derived code for the 16S rRNA gene analyses in this study.
Funders | Funder number |
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European Research Council | 854088 |
NESCC | SIAM 024002002, 02001001 |
Havsochvattenmyndigheten DNR | VI.Veni.212.040 |
Keywords
- anaerobic oxidation of methane
- coastal sediments
- eutrophication
- euxinia