Zooplankton fecal pellets constitute a major component of passively sinking particles in the ocean. The sinking of zooplankton fecal pellets provides an efficient vehicle for the transfer and sequestration of particulate organic carbon (POC) in the deep sea, which has been widely reported in different regions. However, most existing studies focus on the sinking flux of fecal pellets within the upper ocean, while lower mesopelagic and bathypelagic zones are rarely investigated. Here, we report the spatiotemporal flux variation of zooplankton fecal pellets collected by two sediment traps deployed in mesopelagic and bathypelagic zones (500 m and 2190 m, respectively) of the South China Sea from June 2020 to May 2022, and compare it with deep-sea (>500 m) fecal pellet flux data reported in the global ocean. In the South China Sea, fecal pellet fluxes display distinct seasonal patterns due to the control of the East Asian monsoon system, with higher fluxes in winter and spring, and lower fluxes in summer and autumn. Small fecal pellets (width < 100 μm) dominate the overall pellet numerical flux (more than 98 %), while rare large pellets (width > 100 μm) account for averaging 20 % of fecal pellet carbon flux. Both large and small pellet fluxes appear to be higher at 2190 m, mainly due to the in-situ reworking and repackaging of deep-dwelling zooplankton communities, as well as the input of lateral advection from high productive continental coasts and shelves. Identifiable zooplankton fecal pellets constitute approximately 10 % to the total POC flux in the deep South China Sea. Comparing the eutrophic polar and upwelling regions with mesotrophic and oligotrophic regions, we find a good correlation between marine primary production and fecal pellet carbon export. On the global scale, carbon fluxes through zooplankton fecal pellets to the deep sea are mainly constrained by the grazing impacts of zooplanktons, influenced by temperature, zooplankton biomass, and zooplankton size spectrum.

中文翻译：

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浮游动物粪便颗粒通量和碳输出：南海记录及其全球比较


浮游动物粪便颗粒是海洋中被动下沉颗粒的主要组成部分。浮游动物粪便颗粒的沉降为深海颗粒有机碳 （POC） 的转移和封存提供了一种有效的载体，这在不同地区已得到广泛报道。然而，现有的大多数研究都集中在上层海洋中粪便颗粒的下沉通量上，而下层中上层和深海区很少被研究。本文报道了 2020 年 6 月至 2022 年 5 月在南海中上层区和深海区（分别为 500 m 和 2190 m）部署的两个沉积物陷阱收集的浮游动物粪便颗粒的时空通量变化，并将其与全球海洋报道的深海 （x3E500 m） 粪便颗粒通量数据进行比较。在南海，由于东亚季风系统的控制，粪便颗粒通量表现出明显的季节性模式，冬季和春季的通量较高，夏季和秋季的通量较低。小粪便颗粒（宽度 < 100 μm）在颗粒总通量中占主导地位（超过 98 %），而罕见的大颗粒（宽度 > 100 μm）平均占粪便颗粒碳通量的 20%。在 2190 m 处，大颗粒和小颗粒通量似乎都更高，这主要是由于深部浮游动物群落的原位返工和重新包装，以及来自高产大陆海岸和大陆架的横向平流输入。可识别的浮游动物粪便颗粒约占南海深海总 POC 通量的 10%。将富营养化极地和上升流区域与中营养和寡营养区域进行比较，我们发现海洋初级生产和粪便颗粒碳输出之间具有良好的相关性。 在全球范围内，通过浮游动物粪便颗粒到达深海的碳通量主要受到浮游动物放牧影响的限制，受温度、浮游动物生物量和浮游动物大小谱的影响。