Seasonal production and bacterial utilization of DOC in the Ross Sea, Antarctica

• Main Author: Hugh W. Ducklow
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Antarctic; Austral; Ross Sea; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.7339; http://pal.lternet.edu/docs/bibliography/Public/260lterc.pdf

often dominant component of the euphotic zone biomass throughout much of the world ocean. In Antarctic waters however, the bacterial biomass is a much small-er fraction of the total plankton stock, at least during the Austral summer. In the Ross Sea during the 1996-1997 growing season, bacterial abundance reached a peak of 2-3 x 109 cells liter-!, comparable to peak levels in the fertile regions of the world ocean, but bacterial biomass was a paltry 5 % of the phytoplankton stock. Bacterial production ranged from <1 to 22 % of the daily primary produc-tion, averaging 6 % during October-April. Bacterial abundance and production were significantly correlated with the accumulation of semilabile dissolved organic carbon (DOC) over the growing season, indicating the importance of this carbon pool as a source of bacterial nutrition. Bacterial production increased prior to any increase in temperature. The semilabile DOC is entirely consumed by the end of the growing season. A microbial carbon budget based on these observa-tions suggests that ca. 30 % of the total annual primary production is metabolized by bacteria. Bacterioplankton biomass accumulation and production rates are reg-ulated by the amount of labile dissolved organic carbon produced on seasonal times cales in the upper 150 m of the Ross Sea. This relationship argues for the predominance of bottom-up control of bacterial standing stocks in these waters, possibly in contrast to other Antarctic coastal regions.