Methane fluxes from coastal sediments are enhanced by macrofauna

Methane fluxes from coastal sediments are enhanced by macrofauna

Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change. Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of trace gas, isotope...

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Published in:Scientific reports Vol. 7; no. 1; pp. 13145 - 10
Main Authors: Bonaglia, Stefano, Brüchert, Volker, Callac, Nolwenn, Vicenzi, Alessandra, Chi Fru, Ernest, Nascimento, Francisco J. A.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 13-10-2017
Nature Publishing Group
Subjects:
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704/47/4113
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Bacteria
Benthic fauna
Biogeochemistry
biogeokemi
Bioturbation
Bivalvia
Carbon cycle
Climate change
Denitrifying bacteria
Element cycles
Greenhouse effect
Greenhouse gases
Humanities and Social Sciences
Isotopes
Low temperature
Macrofauna
Methane
Methanogenesis
Microbial ecology
Mollusks
multidisciplinary
Nitrous oxide
Science
Science (multidisciplinary)
Sediments
Stable isotope analysis
Symbionts
Water column
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Summary:Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change. Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of trace gas, isotope, and molecular analyses, we studied the direct and indirect contribution of two macrofaunal groups, polychaetes and bivalves, to methane and nitrous oxide fluxes from coastal sediments. Our results indicate that macrofauna increases benthic methane efflux by a factor of up to eight, potentially accounting for an estimated 9.5% of total emissions from the Baltic Sea. Polychaetes indirectly enhance methane efflux through bioturbation, while bivalves have a direct effect on methane release. Bivalves host archaeal methanogenic symbionts carrying out preferentially hydrogenotrophic methanogenesis, as suggested by analysis of methane isotopes. Low temperatures (8 °C) also stimulate production of nitrous oxide, which is consumed by benthic denitrifying bacteria before it reaches the water column. We show that macrofauna contributes to GHG production and that the extent is dependent on lineage. Thus, macrofauna may play an important, but overlooked role in regulating GHG production and exchange in coastal sediment ecosystems.
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ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-017-13263-w