USAP-DC

The ocean plays a critical role in sequestering CO2 by exporting fixed carbon to the deep ocean through the biological pump. There is a pressing need to understand the systematics of carbon export in the Southern Ocean in the context of global warming because of the sensitivity of this region to climate change, already manifested as significant temperature increases. Numerous studies have indicated that Fe supply is a primary control on phytoplankton biomass and productivity in the Southern Ocean. The results from previous cruises in Feb-Mar 2004 and Jul-Aug 2006 have revealed the major natural Fe fertilization from Fe-rich shelf waters to the Fe-limited high nutrient low chlorophyll (HNLC) Antarctic Circumpolar Current Surface Water (ASW) in the southern Drake Passage, producing a series of phytoplankton blooms. Remaining questions include: How is natural Fe transported to the euphotic zone through small-meso-large scale horizontal-vertical transport and mixing in different HNLC ACC areas? How does plankton community structure evolve in response to a natural Fe addition, how does Fe speciation respond to biogeochemical processes, and how is Fe recycled to determine the longevity of phytoplankton blooms? How does the export of POC evolve as a function of upwelling-mixing, Fe addition-recycling and bacteria-plankton structure? This synthesis proposal will address these fundamental questions using a unique dataset combining multiyear physical, Fe and biogeochemical data collected between 2004 and 2006 from 2 NSF-funded Fe fertilization experiment cruises and 3 Antarctic Marine Living Resource (AMLR) cruises in the southern Drake Passage and southwestern Scotia Sea through collaboration with scientists in the AMLR program and US Southern Ocean GLOBEC projects. All investigators involved in this study are engaged in graduate and undergraduate instruction, and mentoring of postdoctoral researchers. Each P.I. will incorporate key elements of the proposed syntheses in our lectures, problem sets and group projects. The project includes support to convene a 4-5 day international workshop on natural Fe fertilization at Woods Hole Oceanographic Institution. The workshop will include scientists from United Kingdom, France and Germany who have conducted natural Fe fertilization experiments, and Korea and China who are planning to conduct natural Fe fertilization experiments. The participation of graduate students and postdoctoral scholars will be especially encouraged. The results will be published in a Deep-Sea Research II special issue.

Person	Role
Mitchell, B.	Investigator
Azam, Farooq	Co-Investigator
Barbeau, Katherine	Co-Investigator
Gille, Sarah	Co-Investigator
Holm-Hansen, Osmund	Co-Investigator
Measures, Christopher	Investigator
Selph, Karen	Co-Investigator

Antarctic Organisms and Ecosystems	Award # 0948357
Antarctic Organisms and Ecosystems	Award # 0948338

NSF-ANT09-48338
NSF-ANT09-48357

None in the Database

Repository	Title (link)	Format(s)	Status
BCO-DMO	Project: Blue Water Zone	None	exist
BCO-DMO	Trace Metal data 2006 (ID3801)	None	exist
BCO-DMO	Trace Metals - 2004	None	exist

1. Prend, C. J., Gille, S. T., Talley, L. D., Mitchell, B. G., Rosso, I., & Mazloff, M. R. (2019). Physical Drivers of Phytoplankton Bloom Initiation in the Southern Ocean’s Scotia Sea. Journal of Geophysical Research: Oceans, 124(8), 5811–5826. (doi:10.1029/2019jc015162)
2. Carranza, M. M., Gille, S. T., Franks, P. J. S., Johnson, K. S., Pinkel, R., & Girton, J. B. (2018). When Mixed Layers Are Not Mixed. Storm‐Driven Mixing and Bio‐optical Vertical Gradients in Mixed Layers of the Southern Ocean. Journal of Geophysical Research: Oceans, 123(10), 7264–7289. (doi:10.1029/2018jc014416)
3. Carranza, M. M., & Gille, S. T. (2015). Southern Ocean wind-driven entrainment enhances satellite chlorophyll-a through the summer. Journal of Geophysical Research: Oceans, 120(1), 304–323. (doi:10.1002/2014jc010203)
4. Gille, S. T., Carranza, M. M., Cambra, R., & Morrow, R. (2014). Wind-induced upwelling in the Kerguelen Plateau region. Biogeosciences, 11(22), 6389–6400. (doi:10.5194/bg-11-6389-2014)
5. Gille, S. T., Carranza, M. M., Cambra, R., & Morrow, R. (2014). Wind-induced upwelling in the Kerguelen Plateau Region. (doi:10.5194/bgd-11-8373-2014)