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Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments

Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments
Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments
Anthropogenic stressors can alter the structure and functioning of infaunal communities, which are key drivers of the carbon cycle in marine soft sediments. Nonetheless, the compounded effects of anthropogenic stressors on carbon fluxes in soft benthic systems remain largely unknown. Here, we investigated the cumulative effects of ocean acidification (OA) and hypoxia on the organic carbon fate in marine sediments, through a mesocosm experiment. Isotopically labelled macroalgal detritus (13C) was used as a tracer to assess carbon incorporation in faunal tissue and in sediments under different experimental conditions. In addition, labelled macroalgae (13C), previously exposed to elevated CO2, were also used to assess the organic carbon uptake by fauna and sediments, when both sources and consumers were exposed to elevated CO2. At elevated CO2, infauna increased the uptake of carbon, likely as compensatory response to the higher energetic costs faced under adverse environmental conditions. By contrast, there was no increase in carbon uptake by fauna exposed to both stressors in combination, indicating that even a short‐term hypoxic event may weaken the ability of marine invertebrates to withstand elevated CO2 conditions. In addition, both hypoxia and elevated CO2 increased organic carbon burial in the sediment, potentially affecting sediment biogeochemical processes. Since hypoxia and OA are predicted to increase in the face of climate change, our results suggest that local reduction of hypoxic events may mitigate the impacts of global climate change on marine soft‐sediment systems.
1354-1013
4165-4178
Ravaglioli, Chiara
079a87f3-760a-424e-b907-17c9bef4f89f
Bulleri, Fabio
bcd65a86-a185-4b29-8068-12918b1329e5
Rühl, Saskia
725215f8-08a4-4fb8-8284-2d6b3efd75cb
Mccoy, Sophie J.
fc6d991b-16bb-4c5b-9619-27c9005f26c0
Findlay, Helen S.
22b14520-0926-413e-8fd2-c5180c839eee
Widdicombe, Stephen
3ecf2b3e-6b3f-4f2f-86c5-baf070e8c82b
Queirós, Ana M.
d025b945-6df7-4038-a887-eea952e07182
Ravaglioli, Chiara
079a87f3-760a-424e-b907-17c9bef4f89f
Bulleri, Fabio
bcd65a86-a185-4b29-8068-12918b1329e5
Rühl, Saskia
725215f8-08a4-4fb8-8284-2d6b3efd75cb
Mccoy, Sophie J.
fc6d991b-16bb-4c5b-9619-27c9005f26c0
Findlay, Helen S.
22b14520-0926-413e-8fd2-c5180c839eee
Widdicombe, Stephen
3ecf2b3e-6b3f-4f2f-86c5-baf070e8c82b
Queirós, Ana M.
d025b945-6df7-4038-a887-eea952e07182

Ravaglioli, Chiara, Bulleri, Fabio, Rühl, Saskia, Mccoy, Sophie J., Findlay, Helen S., Widdicombe, Stephen and Queirós, Ana M. (2019) Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments. Global Change Biology, 25 (12), 4165-4178. (doi:10.1111/gcb.14806).

Record type: Article

Abstract

Anthropogenic stressors can alter the structure and functioning of infaunal communities, which are key drivers of the carbon cycle in marine soft sediments. Nonetheless, the compounded effects of anthropogenic stressors on carbon fluxes in soft benthic systems remain largely unknown. Here, we investigated the cumulative effects of ocean acidification (OA) and hypoxia on the organic carbon fate in marine sediments, through a mesocosm experiment. Isotopically labelled macroalgal detritus (13C) was used as a tracer to assess carbon incorporation in faunal tissue and in sediments under different experimental conditions. In addition, labelled macroalgae (13C), previously exposed to elevated CO2, were also used to assess the organic carbon uptake by fauna and sediments, when both sources and consumers were exposed to elevated CO2. At elevated CO2, infauna increased the uptake of carbon, likely as compensatory response to the higher energetic costs faced under adverse environmental conditions. By contrast, there was no increase in carbon uptake by fauna exposed to both stressors in combination, indicating that even a short‐term hypoxic event may weaken the ability of marine invertebrates to withstand elevated CO2 conditions. In addition, both hypoxia and elevated CO2 increased organic carbon burial in the sediment, potentially affecting sediment biogeochemical processes. Since hypoxia and OA are predicted to increase in the face of climate change, our results suggest that local reduction of hypoxic events may mitigate the impacts of global climate change on marine soft‐sediment systems.

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More information

Accepted/In Press date: 27 July 2019
e-pub ahead of print date: 18 December 2019
Published date: December 2019

Identifiers

Local EPrints ID: 439485
URI: http://eprints.soton.ac.uk/id/eprint/439485
ISSN: 1354-1013
PURE UUID: 506cfe9c-b7fd-425c-8d1c-2439b39e9a85
ORCID for Saskia Rühl: ORCID iD orcid.org/0000-0002-4650-6045

Catalogue record

Date deposited: 24 Apr 2020 16:30
Last modified: 07 Oct 2020 01:31

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Contributors

Author: Chiara Ravaglioli
Author: Fabio Bulleri
Author: Saskia Rühl ORCID iD
Author: Sophie J. Mccoy
Author: Helen S. Findlay
Author: Stephen Widdicombe
Author: Ana M. Queirós

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