Interannual variation of summer zooplankton size structure and its relation to
physical and biological processes in the Yellow Sea and East China Sea
Yongjiu Xu1,2, Joji Ishizaka1, Meixun Zhao2 and Jing Zhang3
1
School of Fishery, Zhejiang Ocean University, Zhoushan, Zhejiang, PR China
E-mail: xyj-20012318@hotmail.com
2
Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya, Japan
3
Key Laboratory of Marine Chemistry Theory and Technology of the Ministry of Education, Ocean
University of China, Qingdao, PR China
4
Graduate School of Science and Engineering, Toyama University, Toyama, Japan
Interannual variation of summer zooplankton size community and its relation to physical
and biological processes in the Yellow Sea (YS) and East China Sea (ECS) were examined
during 2011 to 2013. Zooplankton was size-fractionated with sieves of 2, 1, 0.5, 0.212 and
0.1 mm. The contribution of large size fraction (> 0.5 mm) to total biomass was larger than
the small size fraction (<0.5 mm) in the central YS and Kuroshio Water, whereas the
smaller size fraction (<0.5 mm) was dominant in the Changjiang Diluted Water (CDW) and
its adjacent regions. The geographical distribution of zooplankton size community and its
fraction was significantly affected by the physical and biological features of the YS and
ECS. The large size fraction in all the stations in the central YS was highly related to the
temperature (<10°C) under the thermocline, and these regions corresponded to the Yellow
Sea Bottom Cold Water (YSCBW) region. The small size fraction in the majority of the
stations in the CDW region was related to low surface salinity (<30). This indicates that the
large size zooplankton in the central YS was probably related to the YSBCW, and the small
size zooplankton in CDW region was related to Changjiang discharge water. The
normalized size spectra of zooplankton community in each region were analyzed, and were
compared with other studies to understand the characteristics of the ecosystem in YS and
ECS.