Hales, B. Oregon State University, bhales@oce.orst.edu
Takahashi, T. Lamont-Doherty Earth Observatory of Columbia University, taka@ldeo.columbia.edu
Mathot, S. Virginia Institute of Marine Science, sylviem@vims.edu
Sweeney, C. Lamont-Doherty Earth Observatory of Columbia University, csweeney@ldeo.columbia.edu

 
THREE BIOGEOCHEMICAL REGIMES CHARACTERIZE BLOOM INITIATION IN THE ROSS SEA POLYNYA
 
The high-spatial resolution physical and biogeochemical measurements made with the Lamont Pumping SeaSoar allowed identification of three regions at 76.5 S in the Ross Sea Polynya in Austral Spring of 1997: 1) A weakly-stratified, high-biomass region in the west (170-174 E) with minimal silicate uptake and N:P uptake ratios of about 19 where the assemblage is dominated by Phaeocystis antarctica; 2) A moderately-stratified, high-biomass region in the east (176-179 E) with large silicate uptake and N:P uptake ratios of about 10 where the assemblage is dominated by diatoms; 3) A well-stratified, low-biomass region in the center (174-176 E) with large silicate uptake and N:P uptake ratios of about 10, again dominated by diatoms. We speculate that weak stratification in the west limited diatoms' ability to dominate because they could not optimally adjust to the varying light conditions. Lack of a seed population may prevent phaeocystis from becoming a dominant component of the community in the central and eastern portions of the polynya. High silicate to nitrate uptake ratios in the central portion of the polynya may be due to iron-limited diatom growth, which may explain the low overall productivity and biomass there.
 
Day: Wednesday, Feb. 3
Time: 04:15 - 04:30pm
Location: Sweeney Center
 
Code: SS31WE0415S