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Sinking Diatom Assemblages as a Key Driver for Deep Carbon and Silicon Export in the Scotia Sea (Southern Ocean)

Zúñiga, D. and Sanchez-Vidal, A. and Flexas, M. M. and Carroll, D. and Rufino, M. M. and Spreen, G. and Calafat, A. and Abrantes, F. (2021) Sinking Diatom Assemblages as a Key Driver for Deep Carbon and Silicon Export in the Scotia Sea (Southern Ocean). Frontiers in Earth Science, 9 . Art. No. 579198. ISSN 2296-6463. doi:10.3389/feart.2021.579198.

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Physical and biogeochemical processes in the Southern Ocean are fundamental for modulating global climate. In this context, a process-based understanding of how Antarctic diatoms control primary production and carbon export, and hence global-ocean carbon sequestration, has been identified as a scientific priority. Here we use novel sediment trap observations in combination with a data-assimilative ocean biogeochemistry model (ECCO-Darwin) to understand how environmental conditions trigger diatom ecology in the iron-fertilized southern Scotia Sea. We unravel the role of diatoms assemblage in controlling the biogeochemistry of sinking material escaping from the euphotic zone, and discuss the link between changes in upper-ocean environmental conditions and the composition of settling material exported from the surface to 1,000 m depth from March 2012 to January 2013. The combined analysis of in situ observations and model simulation suggests that an anomalous sea-ice episode in early summer 2012–2013 favored (via restratification due to sea-ice melt) an early massive bloom of Corethron pennatum that rapidly sank to depth. This event drove high biogenic silicon to organic carbon export ratios, while modulating the carbon and nitrogen isotopic signals of sinking organic matter reaching the deep ocean. Our findings highlight the role of diatom ecology in modulating silicon vs. carbon sequestration efficiency, a critical factor for determining the stoichiometric relationship of limiting nutrients in the Southern Ocean.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemDatasets ItemECCO-Darwin model fields
Zúñiga, D.0000-0003-3597-8394
Sanchez-Vidal, A.0000-0002-8209-1959
Flexas, M. M.0000-0002-0617-3004
Carroll, D.0000-0003-1686-5255
Rufino, M. M.0000-0002-0734-7491
Calafat, A.0000-0001-7927-3105
Abrantes, F.0000-0002-9110-0212
Additional Information:© 2021 Zúñiga, Sanchez-Vidal, Flexas, Carroll, Rufino, Spreen, Calafat and Abrantes. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Received: 01 July 2020; Accepted: 26 May 2021; Published: 17 June 2021. The authors are deeply grateful to Joan Puigdefàbregas and Jordi Cateura for their technical assistance in mooring deployment and recovery; Rut Pedrosa-Pàmies and Montse Guart for their help with analytical tasks; the Captain and crew of the R/V Hespérides for their support during the 2012 and 2013 Antarctic cruises. This work was funded by the Spanish Polar Program through the Spanish Research and Innovation (I+D+i) National Plan (grant numbers CTM2009-08287-E/ANT and CTM2011-14056-E/ANT), and supported by the Catalan Government Grups de Recerca Consolidats Grant (2017 SGR 315) and the Internal Research and Technology Development program of the Jet Propulsion Laboratory, California Institute of Technology. DZ was funded by a postdoctoral fellowship (Plan I2C) from Xunta de Galicia (Spain) and performed diatom analysis during her stay at Instituto Português do Mar e da Atmosfera (IPMA), Lisbon, Portugal. Diatom analysis was sponsored by Portuguese national funding through FCT-Fundação para a Ciência e a Tecnologia (UIDB/04326/2020 and DiatBIo PTDC/AAG-GLO/3737/2012 projects). GS was supported by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority programme “Antarctic Research with comparative investigations in Arctic ice areas” SPP 1158 by Grant SITAnt (365778379). Data Availability Statement: The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: The datasets analyzed for this study have been deposited at the Spanish National Polar Data Center (CNDP), ECCO-Darwin model fields are available at: Author Contributions: DZ, AS-V and MMF contributed equally to the writing of the manuscript. MMF conceived, designed the monitoring experiment and acquired the data. AS-V. performed biogeochemical analyses and acquired the data. DZ counted and identified diatom assemblage. DC provided ECCO-Darwin time series and helped with manuscript editing and figure creation. MR performed the statistical analysis. FA provided relevant information for diatoms identification and contributed to the writing of the manuscript. GS contributed with sea-ice analysis and prepared Supplementary Figures S1–S3. TC contributed to the writting of the manuscript and provide valuable support during the whole process. All authors read, edited, and approved the final version of the manuscript. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Funding AgencyGrant Number
Ministerio de Ciencia Y Tecnologia (MCYT)CTM 2009-08287-E/ANT
Ministerio de Ciencia Y Tecnologia (MCYT)CTM 2011-14056-E/ANT
Generalitat de Catalunya2017 SGR 315
JPL Research and Technology Development FundUNSPECIFIED
Xunta de GaliciaUNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)UIDB/04326/2020
Fundação para a Ciência e a Tecnologia (FCT)PTDC/AAG-GLO/3737/2012
Deutsche Forschungsgemeinschaft (DFG)SPP 1158
Deutsche Forschungsgemeinschaft (DFG)365778379
Subject Keywords:diatoms, sea ice, marginal ice zone, carbon export, biogenic silicon, scotia sea, southern ocean, corethron pennatum
Record Number:CaltechAUTHORS:20210727-194728745
Persistent URL:
Official Citation:Zúñiga D, Sanchez-Vidal A, Flexas MM, Carroll D, Rufino MM, Spreen G, Calafat A and Abrantes F (2021) Sinking Diatom Assemblages as a Key Driver for Deep Carbon and Silicon Export in the Scotia Sea (Southern Ocean). Front. Earth Sci. 9:579198. doi: 10.3389/feart.2021.579198
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110037
Deposited By: Tony Diaz
Deposited On:28 Jul 2021 17:46
Last Modified:28 Jul 2021 17:46

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