Picoplankton Dynamics and Their Trophic Roles in the Microbial Food-Web Processes in the Southern East China Sea Upwelling Region During Summer

• Main Authors: An-Yi Tsai, Gwo-Ching Gong, Kuo-Ping Chiang, Pei-Jung Tsai, Chien Fu Chao
• Format: Article
• Language: English
• Published: Chinese Geoscience Union 2014-01-01
• Series: Terrestrial, Atmospheric and Oceanic Sciences
• Subjects: Upwelling; Nanoflagellate; East China Sea
• Online Access: http://tao.cgu.org.tw/images/attachments/v253p435.pdf
• ISSN: 1017-0839; 2311-7680

We monitored the abundance and biomass of nanoflagellates and their potential prey, heterotrophic bacteria, and Synechococcus spp. five times during the summers in 2010 and 2011. We used size-fractionation to measure growth and grazing rates of heterotrophic bacteria and Synechococcus spp. Temporal changes in surface water chlorophyll a (Chl a) concentrations during our study were caused by an influx of nutrient-rich water upwelling into the surface water. The bacterial growth rates ranged from 0.01 to 0.08 h-1 and grazing rates from 0 to 0.06 h-1. Bacterial growth rate had a positive relationship with Chl a concentration. Furthermore, growth and grazing rates of Synechococcus spp. ranged from 0.01 to 0.09 and 0 to 0.02 h-1, respectively. During the study period about 68% of the bacterial production and 41% of the Synechococcus spp. production was grazed by nanoflagellates in the southern East China Sea upwelling region, thus, a large fraction of bacterial biomass is transferred to higher trophic levels via nanoflagellate grazing.