Many foraging fishes spend their vulnerable life stages with low food availability in the oligotrophic Kuroshio. Although they are likely dependent on microbial production as their energy source, there is limited knowledge of the trophodynamics of the planktonic food web in the Kuroshio of the East China Sea (ECS-Kuroshio). Here, we demonstrate energy sources and feeding impacts of microzooplankton on the phytoplankton community based on size-fractionated dilution experiments in the ECS-Kuroshio. Naked ciliates were the most predominant among micro-sized heterotrophs biomass throughout the study area. Pico- to nano-phytoplankton such as Prochlorococcus and haptophytes contributed to total chlorophyll a concentrations. The apparent growth rates in non-diluted bottles without nutrient enrichment were significantly negative for Prochlorococcus and haptophytes. Microzooplankton grazing rates were higher for nano-phytoplankton (0.17–1.45 d⁻¹) compared with those for pico- (0.18–1.23 d⁻¹) and micro-phytoplankton (0.06–0.92 d⁻¹). The community grazing impacts accounted for up to 122% of primary production. These results suggest that one major pathway at lower trophic levels in the ECS-Kuroshio is from pico- and nano-phytoplankton to microzooplankton. This pathway could support energy transfer to higher trophic levels through food resources of mesozooplankton and fish larvae.

在贫营养的黑潮中，许多觅食鱼度过了脆弱的生命阶段，食物供应不足。尽管它们很可能依赖微生物生产作为其能源，但对东海黑潮（ECS-Kuroshio）中浮游食物网的营养动力学的认识有限。在这里，我们根据ECS-Kuroshio中大小分级的稀释实验证明了微浮游动物的能量来源和摄食对浮游植物群落的影响。在整个研究区域，裸纤毛虫是微型异养生物中最主要的生物。微米级至纳米级浮游植物（如原绿球菌和触藻类）有助于总叶绿素a浓度。在没有营养富集的情况下，未稀释瓶中的表观生长速率对原球菌和触藻类植物显着为负。微型浮游动物放牧率纳米浮游植物（0.17-1.45 d较高^-1与那些用于微微相比）（0.18-1.23 d ^-1）和微浮游植物（0.06-0.92 d ^-1）。社区放牧影响占初级生产的122％。这些结果表明，ECS-Kuroshio营养级较低的一个主要途径是从微微浮游植物和纳米浮游植物到微浮游植物。该途径可通过中生浮游动物和鱼幼虫的食物资源支持将能量转移到更高的营养水平。