2002-2003 Science Planning Summary

Biology & Medicine

Dr. Polly Penhale
Program Manager

BO-047-O

NSF/OPP 00-87401
Station: McMurdo Station
RPSC POC: Don Michaelson
Research Site(s): USCG icebreaker, Southern Ross Sea, McMurdo Sound, CSEC

Interannual Variability in the Antarctic Ross Sea (IVARS): Nutrient fields and seasonal productivity II
Dr. Walker O. Smith
Virginia Institute of Marine Sciences
Biological Sciences
wos@vims.edu
Dr. Vernon Asper
University of Southern Mississippi

Deploying Team Members: Lindell K Asper . Vernon Asper . Arne Diereks . Grant M Killian . Jill A Peloquin . Scott M Polk . Amy R Shields . Walker O Smith . Walker T Smith . Joe Tegeder . Jeffery Williams
Research Objectives: During the last few decades, oceanographers and other scientists have found significant variations in Southern Ocean biogeochemical processes from year to year. Some of the more significant of these inter-annual variations are ice extent and concentration, the composition of herbivore communities, and the distributions and reproductive success of bird and marine mammals.

Surprisingly, because it is so central to the food web, little is known about how phytoplankton production varies from year to year or what role these variations may play. The production system in the Ross Sea consists predominantly of two major functional groups - diatoms and Phaeocystis Antarctica, a colonial haptophyte. Project team members will collect time-series data and assess the inter-annual variations of the production of phytoplankton in the southern Ross Sea, Antarctica.

The Ross Sea provides a unique setting for such an investigation, for a number of reasons. Researchers can build upon a de facto time-series already ongoing in the Ross Sea because so many studies have been conducted there in the last decade. It is established that there are fewer species there (relative to some other sites) and that 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.

Inter-annual variations in seasonal production (and of the two major taxa of producers) may be an important factor in the growth and survival of higher trophic levels within the Ross Sea food web. They also shed light on the natural variability of the suite of biogeochemical processes in the region. Having a scientific handle on that baseline of change is important, because of the scientific efforts to model how climate may change in the future. As climate changes, so too will biology be profoundly affected. Accurately modelling and evaluatihng such change means placing it in the context of "natural" inter-annual variability.


Field Season Overview:
The researchers plan to study the interannual variablility of phytoplankton production in the southern Ross Sea. The research team will travel on the USCG icebreaker Polar Star from Hobart, Tasmania to two locations in the southern Ross Sea to deploy instrument moorings that collect high resolution time series samples. During the transit from Hobart and in between mooring sites, they will conduct CTD casts (conductivity, temperature, depth) for water column samples. Phytoplankton samples will be isolated and incubated on the vessel.

Later in the field season, the research team will redeploy to McMurdo Station to recover the moorings During the recovery phase, additional CTD casts will be made at the mooring stations and at stations between the moorings. Some water and sediment samples will be returned to the home institution for analysis.