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Warm plankton soup and red herrings: Calcareous nannoplankton cellular communities and the Paleocene-Eocene thermal maximum

Warm plankton soup and red herrings: Calcareous nannoplankton cellular communities and the Paleocene-Eocene thermal maximum
Warm plankton soup and red herrings: Calcareous nannoplankton cellular communities and the Paleocene-Eocene thermal maximum
Past global warming events such as the Palaeocene–Eocene Thermal Maximum (PETM—56 Ma) are attributed to the release of vast amounts of carbon into the ocean, atmosphere and biosphere with recovery ascribed to a combination of silicate weathering and organic carbon burial. The phytoplanktonic nannoplankton are major contributors of organic and inorganic carbon but their role in this recovery process remains poorly understood and complicated by their contribution to marine calcification. Biocalcification is implicated not only in long-term carbon burial but also both short-term positive and negative climatic feedbacks associated with seawater buffering and responses to ocean acidification. Here, we use exceptional records of preserved fossil coccospheres to reconstruct cell size distribution, biomass production (particulate organic carbon, POC) and (particulate) inorganic carbon (PIC) yields of three contrasting nannoplankton communities (Bass River—outer shelf, Maud Rise—uppermost bathyal, Shatsky Rise—open ocean) through the PETM onset and recovery. Each of the sites shows contrasting community responses across the PETM as a function of their taxic composition and total community biomass. Our results indicate that nannoplankton PIC:POC had no role in short-term climate feedback and, as such, their importance as a source of CO2 to the environment is a red herring. It is nevertheless likely that shifts to greater numbers of smaller cells at the shelf site in particular led to greater carbon transfer efficiency, and that nannoplankton productivity and export across the shelves had a significant modulating effect on carbon sequestration during the PETM recovery.
1364-503X
Gibbs, Samantha
82dfbcbc-3a8a-40da-8a80-fe7ad83f3110
Sheward, Rosie
21a9f84a-f0b2-4488-9ab9-1482ce26e18e
Bown, Paul
8132f693-7f8e-4d02-9b10-df5709f0c487
Poulton, Alex
14bf64a7-d617-4913-b882-e8495543e717
Alvarez, Sarah
d1af0847-7e4a-4983-9cbc-e60d0a6c96aa
Gibbs, Samantha
82dfbcbc-3a8a-40da-8a80-fe7ad83f3110
Sheward, Rosie
21a9f84a-f0b2-4488-9ab9-1482ce26e18e
Bown, Paul
8132f693-7f8e-4d02-9b10-df5709f0c487
Poulton, Alex
14bf64a7-d617-4913-b882-e8495543e717
Alvarez, Sarah
d1af0847-7e4a-4983-9cbc-e60d0a6c96aa

Gibbs, Samantha, Sheward, Rosie, Bown, Paul, Poulton, Alex and Alvarez, Sarah (2018) Warm plankton soup and red herrings: Calcareous nannoplankton cellular communities and the Paleocene-Eocene thermal maximum. Philosophical Transactions of The Royal Society A, 376 (2130). (doi:10.1098/rsta.2017.0075).

Record type: Article

Abstract

Past global warming events such as the Palaeocene–Eocene Thermal Maximum (PETM—56 Ma) are attributed to the release of vast amounts of carbon into the ocean, atmosphere and biosphere with recovery ascribed to a combination of silicate weathering and organic carbon burial. The phytoplanktonic nannoplankton are major contributors of organic and inorganic carbon but their role in this recovery process remains poorly understood and complicated by their contribution to marine calcification. Biocalcification is implicated not only in long-term carbon burial but also both short-term positive and negative climatic feedbacks associated with seawater buffering and responses to ocean acidification. Here, we use exceptional records of preserved fossil coccospheres to reconstruct cell size distribution, biomass production (particulate organic carbon, POC) and (particulate) inorganic carbon (PIC) yields of three contrasting nannoplankton communities (Bass River—outer shelf, Maud Rise—uppermost bathyal, Shatsky Rise—open ocean) through the PETM onset and recovery. Each of the sites shows contrasting community responses across the PETM as a function of their taxic composition and total community biomass. Our results indicate that nannoplankton PIC:POC had no role in short-term climate feedback and, as such, their importance as a source of CO2 to the environment is a red herring. It is nevertheless likely that shifts to greater numbers of smaller cells at the shelf site in particular led to greater carbon transfer efficiency, and that nannoplankton productivity and export across the shelves had a significant modulating effect on carbon sequestration during the PETM recovery.

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Gibbs_etal_2018accepted - Accepted Manuscript
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Accepted/In Press date: 21 May 2018
e-pub ahead of print date: 3 September 2018
Published date: 13 October 2018

Identifiers

Local EPrints ID: 422299
URI: http://eprints.soton.ac.uk/id/eprint/422299
ISSN: 1364-503X
PURE UUID: 9e1f31c7-cad2-4a3f-bd31-82695eca501e

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Date deposited: 20 Jul 2018 16:30
Last modified: 10 Jan 2022 05:59

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Contributors

Author: Samantha Gibbs
Author: Rosie Sheward
Author: Paul Bown
Author: Alex Poulton
Author: Sarah Alvarez

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