中型浮游动物是海洋食物链的关键营养级，通过摄食将浮游植物固定的能量到传递到鱼类等更高营养级，并通过排粪作用将生源碳通过生物泵的传递到深海。本项目研究人员利用CHOICE-C I南海北部四个季节航次的中型浮游动物生物量和摄食影响的变化，探讨中型浮游动物在食物链能量传递和下行控制中的作用。调查表明，南海北部的中型浮游动物生物量主要由上行效应控制，春季的陆架区域和冬季大洋站位中型浮游动物的增长是对浮游植物叶绿素a浓度增长的响应，而后者主要是响应了的营养输入和冬季海水混合引起营养增加。然而总体上，南海北部中型浮游动物对浮游植物的摄食影响较小，每天能摄食0.7～21.5%的浮游植物，如果不考虑极微型浮游植物（<2 μm），中型浮游动物对浮游植物的控制可达到31%/天（春季）。尽管它们对直接从浮游植物中获取生物量的作用不大，但它们通过捕食微型浮游动物形成生物量和对碳泵的贡献不容忽视，这需要进一步开展研究浮游动物排粪才能深刻评价中型浮游动物在南海北部生物泵中的作用。

南海四个季节中型浮游动物生物量（mg/m³）的分布

Chen M., H. Liu, S. Song, S. Sun. Size-fractionated mesozooplankton biomass and grazing impact on phytoplankton in Northern South China Sea during four seasons. 2015, Deep-Sea Res. II, http://dx.doi.org/10.1016/j.dsr2.2015.02.026i

Abstract：Biomass and grazing impact of three size fractions of mesozooplankton were investigated across a wide range of trophic conditions in northern South China Sea(SCS) during four seasonal cruises from July 2009 to May 2011. The grazing impact of mesozooplankton was determined by measurements of gut fluorescence and experimentally-derived gut clearance coefficients. In the northern SCS, the variation in mesozooplankton biomass was influenced by bottom-up effects. Due to riverine runoff to the shelf and winter mixing in oceanic areas, an increase in mesozooplankton biomass was observed in late spring corresponding to an increase in Chl a concentrations. However, because a significant portion of the Chl a came from pico-sizedphytoplankton can not be directly consumed by most mesozooplankton, especially in the oceanic waters during autumn and spring, the bottom-up effect was rather weak. Mesozooplankton consumed 0.7–21.5% of phytoplankton Chl a standing stocks daily, and it was higher in shallow shelf waters than in oceanic waters during spring and summer due to combined effects of mesozooplankton feeding behavior (higher herbivory in shelf waters) and phytoplankton composition(higher contribution of pico-sized phytoplankton in oceanic waters). If only the 42 μm phytoplankton were considered, the grazing impact by mesozooplankton became substantial, reaching ~31%d^_1. Among the three size fractions of mesozooplankton, large-sized mesozooplankton (41000 mm) dominated the total biomass and contributed more than 50% of the herbivory.