USAP-DC

The Ross Sea continental shelf is one of the most productive areas in the Southern Ocean, and may comprise a significant, but unaccounted for, oceanic CO2 sink, largely driven by phytoplankton production. The processes that control the magnitude of primary production in this region are not well understood, but data suggest that iron limitation is a factor. Field observations and model simulations indicate four potential sources of dissolved iron to surface waters of the Ross Sea: (1) circumpolar deep water intruding from the shelf edge; (2) sediments on shallow banks and nearshore areas; (3) melting sea ice around the perimeter of the polynya; and (4) glacial meltwater from the Ross Ice Shelf. The principal investigators hypothesize that hydrodynamic transport via mesoscale currents, fronts, and eddies facilitate the supply of dissolved iron from these four sources to the surface waters of the Ross Sea polynya. These hypotheses will be tested through a combination of in situ observations and numerical modeling, complemented by satellite remote sensing. In situ observations will be obtained during a month-long cruise in the austral summer. The field data will be incorporated into model simulations, which allow quantification of the relative contributions of the various hypothesized iron supply mechanisms, and assessment of their impact on primary production. The research will provide new insights and a mechanistic understanding of the complex oceanographic phenomena that regulate iron supply, primary production, and biogeochemical cycling. The research will thus form the basis for predictions about how this system may change in a warming climate. The broader impacts include training of graduate and undergraduate students, international collaboration, and partnership with several ongoing outreach programs that address scientific research in the Southern Ocean. The research also will contribute to the goals of the international research programs ICED (Integrated Climate and Ecosystem Dynamics) and GEOTRACES (Biogeochemical cycling and trace elements in the marine environment).

Person	Role
Smith, Walker	Investigator
McGillicuddy, Dennis	Investigator

Antarctic Organisms and Ecosystems	Award # 0944254
Antarctic Organisms and Ecosystems	Award # 0944165

NSF-ANT09-44165
NSF-ANT09-44254

Deployment	Type
NBP1201	ship expedition

None in the Database

Repository	Title (link)	Format(s)	Status
BCO-DMO	Project data: Processes Regulating Iron Supply at the Mesoscale - Ross Sea	None	exist
BCO-DMO	Data from expdition NBP1201	None	exist
R2R	Expedition Data	None	exist

1. Li, Y., McGillicuddy, D. J., Dinniman, M. S., & Klinck, J. M. (2017). Processes influencing formation of low-salinity high-biomass lenses near the edge of the Ross Ice Shelf. Journal of Marine Systems, 166, 108–119. (doi:10.1016/j.jmarsys.2016.07.002)
2. Ryan-Keogh, T. J., DeLizo, L. M., Smith, W. O., Sedwick, P. N., McGillicuddy, D. J., Moore, C. M., & Bibby, T. S. (2017). Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica. Journal of Marine Systems, 166, 87–96. (doi:10.1016/j.jmarsys.2016.08.014)
3. Fernández‐González, C., Pérez‐Lorenzo, M., Pratt, N., Moore, C. M., Bibby, T. S., & Marañón, E. (2020). Effects of Temperature and Nutrient Supply on Resource Allocation, Photosynthetic Strategy, and Metabolic Rates of Synechococcus sp. Journal of Phycology, 56(3), 818–829. (doi:10.1111/jpy.12983)
4. Dinniman, M. S., Klinck, J. M., Hofmann, E. E., & Smith, W. O. (2018). Effects of Projected Changes in Wind, Atmospheric Temperature, and Freshwater Inflow on the Ross Sea. Journal of Climate, 31(4), 1619–1635. (doi:10.1175/jcli-d-17-0351.1)
5. Smith, W. O., Dinniman, M. S., Hofmann, E. E., & Klinck, J. M. (2014). The effects of changing winds and temperatures on the oceanography of the Ross Sea in the 21st century. Geophysical Research Letters, 41(5), 1624–1631. (doi:10.1002/2014gl059311)
6. Smith, W. O., & Kaufman, D. E. (2018). Climatological temporal and spatial distributions of nutrients and particulate matter in the Ross Sea. Progress in Oceanography, 168, 182–195. (doi:10.1016/j.pocean.2018.10.003)
7. Smith, W. O., & Donaldson, K. (2015). Photosynthesis–irradiance responses in the Ross Sea, Antarctica: a meta-analysis. Biogeosciences, 12(11), 3567–3577. (doi:10.5194/bg-12-3567-2015)
8. Mack, S. L., Dinniman, M. S., Klinck, J. M., McGillicuddy, D. J., & Padman, L. (2019). Modeling Ocean Eddies on Antarctica’s Cold Water Continental Shelves and Their Effects on Ice Shelf Basal Melting. Journal of Geophysical Research: Oceans, 124(7), 5067–5084. (doi:10.1029/2018jc014688)
9. Smith, W. O., Delizo, L. M., Herbolsheimer, C., & Spencer, E. (2017). Distribution and abundance of mesozooplankton in the Ross Sea, Antarctica. Polar Biology, 40(12), 2351–2361. (doi:10.1007/s00300-017-2149-5)
10. Smith, W. O., & Donaldson, K. A. (2014). Photosynthesis–irradiance responses in the Ross Sea, Antarctica: a meta-analysis. (doi:10.5194/bgd-11-18045-2014)
11. Mosby, A. F., & Smith, W. O. (2016). Structural equation modeling of the influence of environmental factors on summer phytoplankton growth in the Ross Sea. Polar Biology, 40(2), 291–299. (doi:10.1007/s00300-016-1953-7)
12. Phan-Tan, L., Nguyen-Ngoc, L., Smith, W. O., & Doan-Nhu, H. (2018). A new dinoflagellate species, Protoperidinium smithii H. Doan-Nhu, L. Phan-Tan et L. Nguyen-Ngoc sp. nov., and an emended description of Protoperidinium defectum (Balech 1965) Balech 1974 from the Ross Sea, Antarctica. Polar Biology, 41(5), 983–992. (doi:10.1007/s00300-018-2262-0)