USAP-DC

The objectives of this proposal are to investigate the controls on the large-scale distribution and production of the two major bloom-forming phytoplankton taxa in the Southern Ocean, diatoms and Phaeocystis Antarctica. These two groups, through their involvement in the biogeochemical cycles of carbon, sulfur and nutrient elements, may have played important roles in the climate variations of the late Quaternary, and they also may be key players in future environmental change. A current paradigm is that irradiance and iron availability drive phytoplankton dynamics in the Southern Ocean. Recent work, however, suggests that carbon dioxide (CO2) concentrations may also be important in structuring algal assemblages, due to species-specific differences in the physiology. This proposal examines the interactive effects of iron, light and CO2 on the physiology, ecology and relative dominance of Phaeocystis and diatoms in the Southern Ocean. The Ross Sea is an ideal system in which to investigate the environmental factors that regulate the distribution and production of these two algal groups, since it is characterized by seasonal blooms of both P. Antarctica and diatoms that are typically separated in both space and time. This study will take the form of an interdisciplinary investigation that includes a field survey and statistical analysis of algal assemblage composition, iron, mixed layer depth, and CO2 levels in the southern Ross Sea, coupled with shipboard experiments to examine the response of diatom and P. Antarctica assemblages to high and low levels of iron, light and CO2 during spring and summer.
This project will provide information on some of the major factors controlling the production and distribution of the two major bloom forming phytoplankton in the Southern Ocean and the related biogeochemical cycling of carbon, sulfur and nutrient elements. The results may ultimately advance the ability to predict how the Southern Ocean will be affected by and possibly modulate future climate change. This project will also make significant educational contributions at several levels, including the planned research involvement of graduate and undergraduate students, postdoctoral associates, a student teacher, and community outreach and educational activities. A number of activities are planned to interface the project with K-12 education. Presentations will be made at local schools to discuss the research and events of the research cruise. During the cruise there will be daily interactive email contact with elementary classrooms. Established websites will be used to allow students to learn about the ongoing research, and to allow researchers to communicate with students through text and downloaded images.

Person	Role
Ditullio, Giacomo	Investigator
Smith, Walker	Investigator
Dryer, Jennifer	Co-Investigator
Neale, Patrick	Investigator

Antarctic Organisms and Ecosystems	Award # 0741411
Antarctic Ocean and Atmospheric Sciences	Award # 0338350
Antarctic Organisms and Ecosystems	Award # 0338157
Antarctic Ocean and Atmospheric Sciences	Award # 0338097
Antarctic Organisms and Ecosystems	Award # 0338097
Antarctic Organisms and Ecosystems	Award # 0127037

NBP0508
NSF-ANT03-38097_1
NBP0305
NBP0608
NBP0601
smith_opp0338157

None in the Database

Repository	Title (link)	Format(s)	Status
R2R	Expedition Data	None	exist
R2R	Expedition Data	None	exist
R2R	Expedition Data	None	exist
R2R	Expedition Data	None	exist
USAP-DC	Interactive Effects of Iron, Light and Carbon Dioxide on Phytoplankton Community Dynamics in the Ross Sea	None	exist
USAP-DC	Processed Fluid Chemistry Data from the Ross Sea acquired during the Nathaniel B. Palmer expedition NBP0601	None	exists

1. Smyth, R. L., Akan, C., Tejada‐Martínez, A., & Neale, P. J. (2017). Quantifying phytoplankton productivity and photoinhibition in the R oss S ea P olynya with large eddy simulation of L angmuir circulation. Journal of Geophysical Research: Oceans, 122(7), 5545–5565. (doi:10.1002/2017jc012747)
2. Smith, W. O., Tozzi, S., Long, M. C., Sedwick, P. N., Peloquin, J. A., Dunbar, R. B., … DiTullio, G. R. (2013). Spatial and temporal variations in variable fluoresence in the Ross Sea (Antarctica): Oceanographic correlates and bloom dynamics. Deep Sea Research Part I: Oceanographic Research Papers, 79, 141–155. (doi:10.1016/j.dsr.2013.05.002)
3. Liu, X., & Smith, W. O. (2012). Physiochemical controls on phytoplankton distributions in the Ross Sea, Antarctica. Journal of Marine Systems, 94, 135–144. (doi:10.1016/j.jmarsys.2011.11.013)