Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach

Belcher, Anna; Henley, Sian F.; Hendry, Katharine; Wootton, Marianne; Friberg, Lisa; Dallman, Ursula; Wang, Tong; Coath, Christopher; Manno, Clara

doi:https://doi.org/10.5194/bg-20-3573-2023

Articles | Volume 20, issue 16

https://doi.org/10.5194/bg-20-3573-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-20-3573-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 16

Research article

|

25 Aug 2023

Research article |

| 25 Aug 2023

Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach

Anna Belcher, Sian F. Henley, Katharine Hendry, Marianne Wootton, Lisa Friberg, Ursula Dallman, Tong Wang, Christopher Coath, and Clara Manno

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Final revised paper (published on 25 Aug 2023)
Supplement to the final revised paper
Preprint (discussion started on 04 Jan 2023)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on bg-2022-246', Anonymous Referee #1, 14 Feb 2023

Please find my comments in the attached file.

Citation: https://doi.org/10.5194/bg-2022-246-RC1
- AC1: 'Reply on RC1', Anna Belcher, 22 May 2023
  
  Dear Reviewer 1,
  Thank you for taking the time to review our manuscript, please see attached for detailed response to your comments.
  
  Citation: https://doi.org/10.5194/bg-2022-246-AC1
RC2:
'Comment on bg-2022-246', Anonymous Referee #2, 15 Mar 2023

please find my comments in the attached pdf file.

Citation: https://doi.org/10.5194/bg-2022-246-RC2
- AC2: 'Reply on RC2', Anna Belcher, 22 May 2023
  
  Dear Reviewer 2,
  We appreciate the comments you have given us and the time taken to review our manuscript. Please see attached our detailed response to your comments.
  
  Citation: https://doi.org/10.5194/bg-2022-246-AC2
AC3: 'Comment on bg-2022-246', Anna Belcher, 22 May 2023

For attention of reviewers, the marked up version of the manuscript highlighting the changes made to the manuscript in response to their comments.

Citation: https://doi.org/10.5194/bg-2022-246-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (07 Jun 2023) by Sebastian Naeher

AR by Anna Belcher on behalf of the Authors (07 Jun 2023) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (08 Jun 2023) by Sebastian Naeher

RR by Patricia Grasse (20 Jun 2023)

RR by Anonymous Referee #1 (03 Jul 2023)

Suggestions for revision or reasons for rejection

In “Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: A stable isotope approach”, Belcher et al. present a study investigating the seasonal variations of organic matter (POC and PON) and biogenic silica fluxes from two sediment traps located north-West of South Georgia in the Scotia Sea (Southern Ocean). Using stable isotope approaches the authors examine the origin and some of the processes controlling the fluxes they have observed in the traps.

They investigated the differences between two productive events (in February 2018 – summer season – and December 2018 – spring season) and the coupling of C, N and Si fluxes during these events. Their main results are: Particulate fluxes and isotopic compositions were similar in the deep and shallow trap suggesting that most of the remineralization occurred in the upper layer of the water column. Despite a very noisy d15N signal, the synchronicity if the d30Si and d13C signals highlight the coupling between these two elements and the significant role of diatoms in the export of C (and BSi) in the area. Based on the estimation of isotopic baselines associated with the two productive events, they also suggested a change in the source region of the material coming into the sediment traps.

Having reviewed the first version of this manuscript, I greatly appreciate authors’ efforts to improve the reading by carefully re-organizing the different sections. The introduction is clear and describes all the background needed to fully appreciate the manuscript. New elements have been added to the discussion and greatly improve the manuscript. Some minor points will still benefit to be clarified and, although they have already greatly improved the figure, I am personally not convinced that figure 3, which is the most important figure in the manuscript, is presented in the clearest/smartest possible way (but this is my personal taste, the data are currently there).

I detail these points below and, although I recommend publication of the manuscript after minor revisions, I am convinced that this paper will be a great addition to “Biogeosciences”.

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (03 Jul 2023) by Sebastian Naeher

AR by Anna Belcher on behalf of the Authors (12 Jul 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (16 Jul 2023) by Sebastian Naeher

AR by Anna Belcher on behalf of the Authors (16 Jul 2023)

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Short summary

The oceans play a crucial role in the uptake of atmospheric carbon dioxide, particularly the Southern Ocean. The biological pumping of carbon from the surface to the deep ocean is key to this. Using sediment trap samples from the Scotia Sea, we examine biogeochemical fluxes of carbon, nitrogen, and biogenic silica and their stable isotope compositions. We find phytoplankton community structure and physically mediated processes are important controls on particulate fluxes to the deep ocean.