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Phytoplankton responses to dust addition in the Fe–Mn co-limited eastern Pacific sub-Antarctic differ by source region

Phytoplankton responses to dust addition in the Fe–Mn co-limited eastern Pacific sub-Antarctic differ by source region
Phytoplankton responses to dust addition in the Fe–Mn co-limited eastern Pacific sub-Antarctic differ by source region

The seasonal availability of light and micronutrients strongly regulates productivity in the Southern Ocean, restricting biological utilization of macronutrients and CO 2 drawdown. Mineral dust flux is a key conduit for micronutrients to the Southern Ocean and a critical mediator of multimillennial-scale atmospheric CO 2 oscillations. While the role of dust-borne iron (Fe) in Southern Ocean biogeochemistry has been examined in detail, manganese (Mn) availability is also emerging as a potential driver of past, present, and future Southern Ocean biogeochemistry. Here, we present results from fifteen bioassay experiments along a north–south transect in the undersampled eastern Pacific sub-Antarctic zone. In addition to widespread Fe limitation of phytoplankton photochemical efficiency, we found further responses following the addition of Mn at our southerly stations, supporting the importance of Fe–Mn co-limitation in the Southern Ocean. Moreover, addition of different Patagonian dusts resulted in enhanced photochemical efficiency with differential responses linked to source region dust characteristics in terms of relative Fe/Mn solubility. Changes in the relative magnitude of dust deposition, combined with source region mineralogy, could hence determine whether Fe or Mn limitation control Southern Ocean productivity under future as well as past climate states.

biogeochemistry, ecophysiology, phytoplankton
0027-8424
Wyatt, Neil J.
258d214b-9dae-4a5f-acc9-c0a55fb66efd
Birchill, Antony
b2541497-080a-4b7b-a245-3f4135ec1168
Ussher, Simon
ac1386f0-f0a1-4663-8fc5-26dbc178327b
Milne, Angela
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Bouman, Heather A.
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Shoenfelt Troein, Elizabeth
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Pabortsava, Katsiaryna
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Wright, Alan
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Flanagan, Oliver
2be7c8e9-fb2a-4bca-abac-fb649c02cee9
Bibby, Thomas S.
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Martin, Adrian
9d0d480d-9b3c-44c2-aafe-bb980ed98a6d
Moore, C. Mark
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Wyatt, Neil J.
258d214b-9dae-4a5f-acc9-c0a55fb66efd
Birchill, Antony
b2541497-080a-4b7b-a245-3f4135ec1168
Ussher, Simon
ac1386f0-f0a1-4663-8fc5-26dbc178327b
Milne, Angela
39b44fbd-8f5e-40ea-80c9-244c20998020
Bouman, Heather A.
5f21cf59-afa4-42be-b826-c1ac2c6730c4
Shoenfelt Troein, Elizabeth
4651c23a-205e-45f1-8c59-aa0aeb2a676b
Pabortsava, Katsiaryna
89032ead-22c9-40bc-b414-ed59845fc72f
Wright, Alan
88f0d02f-0ebb-4034-8b02-b6f71b3a1cdc
Flanagan, Oliver
2be7c8e9-fb2a-4bca-abac-fb649c02cee9
Bibby, Thomas S.
e04ea079-dd90-4ead-9840-00882de27ebd
Martin, Adrian
9d0d480d-9b3c-44c2-aafe-bb980ed98a6d
Moore, C. Mark
7ec80b7b-bedc-4dd5-8924-0f5d01927b12

Wyatt, Neil J., Birchill, Antony, Ussher, Simon, Milne, Angela, Bouman, Heather A., Shoenfelt Troein, Elizabeth, Pabortsava, Katsiaryna, Wright, Alan, Flanagan, Oliver, Bibby, Thomas S., Martin, Adrian and Moore, C. Mark (2023) Phytoplankton responses to dust addition in the Fe–Mn co-limited eastern Pacific sub-Antarctic differ by source region. Proceedings of the National Academy of Sciences, 120 (28), [e2220111120]. (doi:10.1073/pnas.2220111120).

Record type: Article

Abstract

The seasonal availability of light and micronutrients strongly regulates productivity in the Southern Ocean, restricting biological utilization of macronutrients and CO 2 drawdown. Mineral dust flux is a key conduit for micronutrients to the Southern Ocean and a critical mediator of multimillennial-scale atmospheric CO 2 oscillations. While the role of dust-borne iron (Fe) in Southern Ocean biogeochemistry has been examined in detail, manganese (Mn) availability is also emerging as a potential driver of past, present, and future Southern Ocean biogeochemistry. Here, we present results from fifteen bioassay experiments along a north–south transect in the undersampled eastern Pacific sub-Antarctic zone. In addition to widespread Fe limitation of phytoplankton photochemical efficiency, we found further responses following the addition of Mn at our southerly stations, supporting the importance of Fe–Mn co-limitation in the Southern Ocean. Moreover, addition of different Patagonian dusts resulted in enhanced photochemical efficiency with differential responses linked to source region dust characteristics in terms of relative Fe/Mn solubility. Changes in the relative magnitude of dust deposition, combined with source region mineralogy, could hence determine whether Fe or Mn limitation control Southern Ocean productivity under future as well as past climate states.

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More information

Accepted/In Press date: 16 May 2023
e-pub ahead of print date: 3 July 2023
Published date: 3 July 2023
Additional Information: Funding Information: ACKNOWLEDGMENTS. We thank the captain, officers, and crew of the R.R.S. Discovery DY111 cruise. We are further grateful to Michael Kaplan (Columbia University) for supplying the Patagonian dust sources used in our experiments. Two reviewers are thanked for comments which considerably improved the manuscript. For the purpose of open access, we have applied a CC BY public copyright license to any author-accepted manuscript version arising from this submission. The work was supported by the Natural Environment Research Council UK project Carbon Uptake and Seasonal Traits in Antarctic Remineralisation Depth (CUSTARD) through grants NE/P021328/1 (C.M.M., H.A.B., and T.S.B.), NE/P021336/1 (S.U. and A.M.), and NE/P021247/2 (A.M.).
Keywords: biogeochemistry, ecophysiology, phytoplankton
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Identifiers

Local EPrints ID: 481390
URI: http://eprints.soton.ac.uk/id/eprint/481390
DOI: doi:10.1073/pnas.2220111120
ISSN: 0027-8424
PURE UUID: a7962f60-7d7b-4bc0-950f-73377a718b06
ORCID for Neil J. Wyatt: ORCID iD orcid.org/0000-0002-1080-7778
ORCID for C. Mark Moore: ORCID iD orcid.org/0000-0002-9541-6046

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Date deposited: 24 Aug 2023 17:08
Last modified: 18 Mar 2024 02:51

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Contributors

Author: Neil J. Wyatt ORCID iD
Author: Antony Birchill
Author: Simon Ussher
Author: Angela Milne
Author: Heather A. Bouman
Author: Elizabeth Shoenfelt Troein
Author: Katsiaryna Pabortsava
Author: Alan Wright
Author: Oliver Flanagan
Author: Thomas S. Bibby
Author: Adrian Martin
Author: C. Mark Moore ORCID iD

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