E 2008, by the American Society of Limnology and Oceanography, Inc. Inorganic carbon uptake by Southern Ocean phytoplankton

• Main Authors: Chris Payne, Celine Gueguen, Robert F. Strzepek, Philip W. Boyd, Björn Rost
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Ross Sea; Southern Ocean; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.297.3690; http://www.aslo.org/lo/toc/vol_53/issue_4/1266.pdf

We report the results of laboratory and field studies examining inorganic carbon (Ci) utilization by Southern Ocean phytoplankton. Both in monospecific laboratory cultures of diatoms and Phaeocystis antarctica and in transport. The natural assemblages in the Ross Sea, Ci uptake by phytoplankton was dominated by direct HCO { 3 contribution of HCO { 3 transport to total Ci uptake ranged from 65 % to 95%, with an overall average of,80%. There was no significant difference among diatoms and Phaeocystis in the extent of HCO { 3 transport. Extracellular carbonic anhydrase activity (eCA) was detected in eight of nine laboratory phytoplankton cultures and in all natural assemblages in the Ross Sea. The effective catalytic enhancement of HCO { 3:CO2 interconversion ranged from 1.5- to 13-fold (overall mean,4-fold). Diatom-dominated Ross Sea assemblages had significantly greater eCA levels than did Phaeocystis-dominated assemblages. We found no strong correlations between Ci uptake parameters and in situ CO2 concentrations or chlorophyll a levels in the Ross Sea assemblages. Incubation experiments with natural assemblages showed that HCO { 3 uptake and eCA expression