Brzezinski, M. A. Marine Science Institute, brzezins@lifesci.ucsb.edu
Nelson, D. A. College of Oceanic and Atmospheric Sciences, nelsonda@ucs.orst.edu
Franck, V. M. Marine Science Institute, franck@lifesci.ucsb.edu
Sigmon, D. E. College of Oceanic and Atmospheric Sciences, dsigmon@oce.orst.edu

 
RATES OF BIOGENIC SILICA PRODUCTION WITHIN AN INTENSE DIATOM BLOOM AT THE ANTARCTIC POLAR FRONT AT 170W
 
An intense diatom bloom developed within the strong silicic acid gradient across the Antarctic Polar Front at about 61 degrees S., 170 degrees W. in early December 1997. Both the bloom and the silicic acid gradient moved southward away from the Polar Front with the bloom tracking the center of the silicic acid gradient. The bloom persisted until the end of January 1998, having consumed ca. 40 uM silicic acid from the euphotic zone between 60 and 65 degrees S. Integrated biogenic silica concentrations within the bloom averaged 471 mmol Si m-2 (range 310 - 800). Silica production rates averaged 34.4 mmol Si m-2 d-1 within the bloom (range 8 - 64 ), consistent with diatom growth being the cause of the southward displacement of the silicic acid gradient through time. Integrated siliceous biomass and silica production rates were similar to those reported for ice-edge diatom blooms in the Ross Sea, Antarctica which is among the most productive regions in the Southern Ocean. Our observations indicate that high diatom biomass and high silica production rates also occur in the ice-free open ocean near the Polar Front within the latitudinal band overlying the great sedimentary opal belt.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS31WE1401S