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Reconciliation of the carbon budget in the ocean’s twilight zone

Reconciliation of the carbon budget in the ocean’s twilight zone
Reconciliation of the carbon budget in the ocean’s twilight zone
Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean1, 2. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage3. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude4, 5, 6, 7, 8. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink.
0028-0836
480-483
Giering, Sarah L.C.
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Sanders, Richard
02c163c1-8f5e-49ad-857c-d28f7da66c65
Lampitt, Richard S.
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Anderson, Thomas R.
dfed062f-e747-48d3-b59e-2f5e57a8571d
Tamburini, Christian
445f11f9-4a45-4212-a5be-ba7563a80d14
Boutrif, Mehdi
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Zubkov, Mikhail V.
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Marsay, Chris M.
f18098e4-e58c-4799-a7fc-5d6f8ec95677
Henson, Stephanie A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Saw, Kevin
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Cook, Kathryn
5e057acb-36d1-44ae-934f-b1167898f3ea
Mayor, Daniel J.
a2a9c29e-ffdc-4858-ad65-3a235824a4c9
Giering, Sarah L.C.
db5f59a2-8cf2-44d4-99c4-53756df823dc
Sanders, Richard
02c163c1-8f5e-49ad-857c-d28f7da66c65
Lampitt, Richard S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad
Anderson, Thomas R.
dfed062f-e747-48d3-b59e-2f5e57a8571d
Tamburini, Christian
445f11f9-4a45-4212-a5be-ba7563a80d14
Boutrif, Mehdi
34a78807-202f-4f4d-a0e0-90a0d1c840b7
Zubkov, Mikhail V.
b1dfb3a0-bcff-430c-9031-358a22b50743
Marsay, Chris M.
f18098e4-e58c-4799-a7fc-5d6f8ec95677
Henson, Stephanie A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Saw, Kevin
aba28de9-80bc-426f-8b96-22d637550649
Cook, Kathryn
5e057acb-36d1-44ae-934f-b1167898f3ea
Mayor, Daniel J.
a2a9c29e-ffdc-4858-ad65-3a235824a4c9

Giering, Sarah L.C., Sanders, Richard, Lampitt, Richard S., Anderson, Thomas R., Tamburini, Christian, Boutrif, Mehdi, Zubkov, Mikhail V., Marsay, Chris M., Henson, Stephanie A., Saw, Kevin, Cook, Kathryn and Mayor, Daniel J. (2014) Reconciliation of the carbon budget in the ocean’s twilight zone. Nature, 507, 480-483. (doi:10.1038/nature13123).

Record type: Article

Abstract

Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean1, 2. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage3. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude4, 5, 6, 7, 8. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink.

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Giering Manuscrip&extended figs.pdf - Accepted Manuscript
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Published date: 27 March 2014
Organisations: Ocean and Earth Science, Marine Biogeochemistry, Ocean Technology and Engineering

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Local EPrints ID: 363272
URI: http://eprints.soton.ac.uk/id/eprint/363272
ISSN: 0028-0836
PURE UUID: 82f084a5-610d-4ceb-b0cb-eb6c0cd33061

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Date deposited: 20 Mar 2014 10:11
Last modified: 16 Dec 2019 20:26

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