AME 51:263-274 (2008)  -  DOI: https://doi.org/10.3354/ame01196

Seasonal variations in trophic dynamics of nanoflagellates and picoplankton in coastal waters of the western subtropical Pacific Ocean

An-Yi Tsai1, Kuo-Ping Chiang1,3,4,*, Jeng Chang2,3, Gwo-Ching Gong3

1Institute of Environmental Biology and Fishery Science, 2Institute of Marine Biology, 3Institute of Marine Environmental Chemistry and Ecology, and 4Center for Marine Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 202-24, Taiwan, ROC
*Corresponding author. Email:

ABSTRACT: This investigation was undertaken between August 2002 and July 2003 at a coastal station on the southern edge of the East China Sea. We found a 2-phase (warm season, >25°C [June to October] and cold season, <25°C [November to May]) seasonal cycle with a 10-fold variation in the growth of bacteria (heterotrophic bacteria only) and picophytoplankton, primarily coccoid cyanobacteria (Synechococcus spp.), and nanoflagellate grazing rates upon them. Growth rate in bacteria and Synechococcus spp. appeared to be affected by changes in temperature, and the nanoflagellate grazing rate was controlled by concentrations of bacteria and Synechococcus spp. The seasonal cycles of abundance in bacteria and Synechococcus spp. were a reflection of their changing net growth rates (i.e. picoplankton growth rates – nanoflagellate grazing rates), which were highest at the beginning of the warm season. During the warm season, nanoflagellates consumed an equal amount of bacteria and Synechococcus spp.; therefore, growth in both groups was affected equally by grazing in the warm season. However, during the cold season, bacteria contributed more to nanoflagellate carbon consumed than did Synechococcus spp. because the growth rate of Synechococcus spp. was low. We conclude that during the warm season a significant part of bacteria and Synechococcus spp. carbon is channeled through the microbial loop, possibly making it an important link between primary production and higher trophic levels.


KEY WORDS: Synechococcus spp. · Picoplankton · Nanoflagellate · Microbial loop


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Cite this article as: An-Yi T, Chiang KP, Chang J, Gong GC (2008) Seasonal variations in trophic dynamics of nanoflagellates and picoplankton in coastal waters of the western subtropical Pacific Ocean. Aquat Microb Ecol 51:263-274. https://doi.org/10.3354/ame01196

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