Kirchman, D. L. University of Delaware, kirchman@udel.edu
Meon, B. L. University of Delaware, bmeon@udel.edu
Steward, G. F. Scripps Institution of Oceanography, gsteward@ucsd.edu
Azam, F. Scripps Institution of Oceanography, fazam@ucsd.edu
Ducklow, H. W. College of William and Mary, duck@vims.edu

 
COMPOSITION AND TURNOVER OF SELECTED DOM COMPONENTS IN THE SOUTHERN OCEAN
 
Concentrations and turnover of free and combined sugars and amino acids were examined in the Ross Sea and Polar Front Zone as part of the AESOPS JOGFS program. This presentation will focus on free sugars and dissolved polysaccharides ("combined sugars ") in the Ross Sea because an abundant phytoplankton species (Phaeocystis) in the Ross Sea is known to produce high concentrations of polysaccharides. Our data, however, reveal that concentrations of dissolved polysaccharides are similar to that observed in other oceanic waters without high Phaeocystisabundance. Dissolved polysaccharides averaged about 1.2 uM-C in November (Process 4) and 3 uM-C in January (Process 2) in the Ross Sea, much higher than free glucose concentrations (0.06 uM-C). Glucose was the only free sugar detected, whereas the composition of dissolved polysaccharides was much more varied. This composition was similar to that observed elsewhere and thus lacked any obvious signal (e.g. high glucose) from high Phaeocystisproduction. Uptake of glucose supported a small fraction of bacterial growth (<5%), much less than observed elsewhere (about 30%). These data are consistent with observations of total organic carbon indicating a very rapid transfer of phytoplankton-derived carbon to bacterial carbon without obvious mediation by the dissolved organic pools.
 
Day: Thursday, Feb. 4
Time: 04:00 - 04:15pm
Location: Sweeney Center
 
Code: SS31TH0400S