ABUNDANCE AND BIOMASS DISTRIBUTION OF MICROBIAL ASSEMBLAGES AT THE SURFACE IN THE OCEANIC PROVINCE OF ANTARCTIC OCEAN

• Main Authors: Michie Ishiyama, Juro Hiromi, Atsushi Tanimura, Sadami Kadota
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Antarctic Ocean; Indian; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.554.5177; http://polaris.nipr.ac.jp/~penguin/polarbiosci/issues/pdf/1993-Ishiyama.pdf

length), and microzooplankton (1 5-250 pm in length) were collected from the surface of the Indian and Australian sectors of Antarctic Ocean. The average abundance of bacterioplankton was 4.56xlo4 cells/ml, and the biomass was 0.25 mg c1m3. The values of the autotrophic nanoplankton were 0. 5 ~ 1 0 ~ cellslml and 2.27 mg c1m3, respectively. There were 1. 0 2 ~ 1 0 ~ cellslml of heterotrophic nanoplankton in abundance, and its biomass was 0.71 mg c1m3. About 30 % of the biomass of this assemblage was choanoflagellates. Average abundance and biomass of the microzooplankton were 1. 6 2 ~ 1 0 ~ inds.11 and 3.78 mg c/m3, respectively. A large portion of the abundance and biomass of microzooplankton was oligotrichs. Protozoans within micro-sized (15-250 pm) category which ingest preys similar to or larger than themselves were found where biomass ratio of nanoplankton to microzooplankton was low (<0.3). This may indicate adaptability of the protozoan to a severe food environment. The biomass (log-scale) decreased linearly with increasing individual body weight (log-scale) with a slope of-0.21. This result suggests that smaller protozoans such as heterotrophic nanoplankton and oligotrichs have an important role in the Antarctic Ocean's energy flow. 1.