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

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 ORCID: https://orcid.org/0000-0002-1202-8612; 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). https://doi.org/10.1073/pnas.2220111120

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Official URL: http://dx.doi.org/10.1073/pnas.2220111120

Abstract/Summary

The seasonal availability of light and micronutrients strongly regulates productivity in the Southern Ocean, restricting biological utilization of macronutrients and CO2 drawdown. Mineral dust flux is a key conduit for micronutrients to the Southern Ocean and a critical mediator of multimillennial-scale atmospheric CO2 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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1073/pnas.2220111120
ISSN:	0027-8424
Date made live:	04 Jul 2023 11:37 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/535223

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1073/pnas.2220111120

ISSN:

0027-8424

Date made live:

04 Jul 2023 11:37 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/535223