USAP-DC

During the past few decades of oceanographic research, it has been recognized that significant variations in biogeochemical processes occur among years. Interannual variations in the Southern Ocean are known to occur in ice extent and concentration, in the composition of herbivore communities, and in bird and marine mammal distributions and reproductive success. However, little is known about the interannual variations in production of phytoplankton or the role that these variations play in the food web. This project will collect time series data on the seasonal production of phytoplankton in the southern Ross Sea, Antarctica. Furthermore, it will assess the interannual variations of the production of the two major functional groups of the system, diatoms and Phaeocystis Antarctica, a colonial haptophyte. The Ross Sea provides a unique setting for this type of investigation for a number of reasons. For example, a de facto time-series has already been initiated in the Ross Sea through the concentration of a number of programs in the past ten years. It also is well known that the species diversity is reduced relative to other systems and its seasonal production is as great as anywhere in the Antarctic. Most importantly, seasonal production of both the total phytoplankton community (as well as its two functional groups) can be estimated from late summer nutrient profiles. The project will involve short cruises on the US Coast Guard ice breakers in the southern Ross Sea that will allow the collection of water column nutrient and particulate after data at specific locations in the late summer of each of five years. Additionally, two moorings with in situ nitrate analyzers moored at fifteen will be deployed, thus collecting for the first time in the in the Antarctic a time-series of euphotic zone nutrient concentrations over the entire growing season. All nutrient data will be used to calculate seasonal production for each year in the southern Ross Sea and compared to previously collected information, thereby providing an assessment of interannual variations in net community production. Particulate matter data will allow us to estimate the amount of export from the surface layer by late summer, and therefore calculate the interannual variability of this ecosystem process. Interannual variations of seasonal production (and of the major taxa of producers) are a potentially significant feature in the growth and survival of higher trophic levels within the food web of the Ross Sea. They are also important in order to understand the natural variability in biogeochemical processes of the region. Because polar regions such as the Ross Sea are predicted to be impacted by future climate change, biological changes are also anticipated. Placing these changes in the context of natural variability is an essential element of understanding and predicting such alterations. This research thus seeks to quantify the natural variability of an Antarctic coastal system, and ultimately understand its causes and impacts on food webs and biogeochemical cycles of the Ross Sea.

Person	Role
Smith, Walker	Investigator
Gordon, Arnold	Investigator

Antarctic Organisms and Ecosystems

Award # 0087401

NBP0601A

Deployment	Type
NBP0301B	ship expedition
NBP0305A	ship expedition
NBP0501	ship expedition
NBP0601A	ship expedition

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Fluorometer Data acquired on Moorings deployed the Ross Sea and recovered during the Nathaniel B. Palmer expedition NBP0601A (2006)	None	exists
USAP-DC	Processed Fluid Chemistry Data from the Ross Sea acquired during the Nathaniel B. Palmer expedition NBP0601A	None	exists
R2R	Expedition data of NBP0301B	None	exists
R2R	Expedition data of NBP0305A	None	exists
R2R	Expedition data of NBP0501	None	exists
R2R	Expedition data of NBP0601A	None	exists
USAP-DC	Current Meter Data from the Ross Sea acquired with a Mooring deployed in December 2005 and recovered during the Nathaniel B. Palmer expedition NBP0601A (2006)	None	exists
R2R	Expedition data of NBP0501	None	exists

1. 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)
2. Asper, V., & Smith, W. (2019). Abundance and size distribution of abandoned (ghost) Phaeocystis colonies from profiles conducted during R/V Polar Star cruises in the Ross Sea, Antarctica between 2001 and 2005. Biological and Chemical Oceanography Data Management Office. (doi:10.1575/1912/bco-dmo.768570.1)
3. Asper, V., & Smith, W. (2019). Abundance and size distribution of marine snow aggregates from profiles conducted during R/V Polar Star cruises in the Ross Sea, Antarctica between 2001 and 2005. Biological and Chemical Oceanography Data Management Office. (doi:10.1575/1912/bco-dmo.719478.2)