ORCID
- Simon Ussher: 0000-0001-6724-9212
- Angela Milne: 0000-0002-3304-8962
Abstract
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.
DOI
10.1073/pnas.2220111120
Publication Date
2023-07-03
Publication Title
Proceedings of the National Academy of Sciences
ISSN
0027-8424
Embargo Period
2023-07-20
Recommended Citation
Wyatt, N., Birchill, A., Ussher, S., Milne, A., Bouman, H., Troein, E., Pabortsava, K., Wright, A., Flanagan, O., Bibby, T., Martin, A., & Moore, C. (2023) 'Phytoplankton responses to dust addition in the FeMn co-limited eastern Pacific sub-Antarctic differ by source region', Proceedings of the National Academy of Sciences, . Available at: https://doi.org/10.1073/pnas.2220111120
