Data from: Nanoplankton dominate autumn biomass on the Agulhas Bank

Autumn productivity is key to the large marine ecosystems of the Agulhas Bank, which support numerous economically important regional fisheries. Despite such importance, data is sparce on plankton composition in terms of primary or secondary producers, or on trophic transfer. While investigating autumn plankton composition we found that nanophytoplankton (2-20 μm) dominated carbon stocks, with lower contributions from picophytoplankton (<2 μm) and microphytoplankton (>20 μm). While picoplankton biomass exhibited a relationship with warm nutrient poor waters, nanoplankton showed no clear relationship to environmental parameters. The dominance of nanophytoplankton biomass on the Agulhas Bank highlights a critical role for micro-zooplankton grazing as a trophic transfer between these small plankton, meso-zooplankton and the higher trophic levels that make the bank so important for regional fisheries. Outside of localized coastal upwelling on the Agulhas Bank, this study highlights a significant role for nanoplankton and micro-zooplankton in supporting the bank’s large marine ecosystems.厄加勒斯浅滩（Agulhas Bank）的大型海洋生态系统核心依托于秋季生产力，该区域支撑着众多具有重要经济价值的区域性渔业。尽管其生态与经济价值举足轻重，但目前针对该区域初级或次级生产者的浮游生物组成，以及营养级传递过程的相关数据仍较为匮乏。本研究在调查秋季浮游生物组成时发现，纳米浮游植物（nanophytoplankton，2~20μm）在碳储量中占据主导地位，微微浮游植物（picophytoplankton，<2μm）与微型浮游植物（microphytoplankton，>20μm）的碳贡献占比相对较低。其中，微微浮游植物的生物量与暖水贫营养水域存在显著相关性，而纳米浮游植物的生物量则未表现出与环境参数的明确关联。厄加勒斯浅滩纳米浮游植物生物量的主导地位，凸显出微型浮游动物（micro-zooplankton）的牧食作用在这类小型浮游生物、中型浮游动物（meso-zooplankton）与更高营养级之间的营养级传递中发挥着关键作用——这也是该浅滩对区域性渔业如此重要的核心原因。在厄加勒斯浅滩的局地沿岸上升流区域之外，本研究进一步揭示了纳米浮游植物与微型浮游动物在维持该浅滩大型海洋生态系统运转中所扮演的重要角色。