The fate of organic matter (OM) in the deep ocean remains enigmatic, with little understood regarding the flux and its utilization by deep food webs. We used compound‐specific nitrogen stable isotope ratios of source amino acids measured in particle size classes and deep zooplankton (700–1500 m) to determine the contribution of small (0.7–53 μm) vs. large particles (> 53 μm) to their diet at four sites in the North Pacific. Our results show that small particles constitute between 9% and 98% of zooplankton diets, being the contribution higher at sites with lower flux regimes. The contribution of small particles to the diet of deep zooplankton was also higher when biomass of vertical migrators, and therefore actively transported OM, was lower. Climate‐driven changes in primary production and export are expected to shift particle fluxes to smaller size classes, and thus their importance in midwater food webs may become more widespread.

中文翻译：

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当粒子通量较低时，深浮游动物依靠小粒子

深海中的有机物（OM）的命运仍然是个谜，人们对深层食物网的通量及其利用知之甚少。我们所使用的源的具体化合物的氮稳定同位素比氨基粒径类和深浮游动物（700-1500米）测定氨基酸以确定的小的（0.7-53贡献 μ米）与大颗粒（> 53  μm）在北太平洋的四个地方饮食。我们的结果表明，小颗粒占浮游动物日粮的9％至98％，在通量较低的地区，其贡献更大。当垂直迁徙者的生物量较低时，小颗粒对深层浮游动物饮食的贡献也较高，因此主动运输的OM较低。预期由气候驱动的初级生产和出口变化会将颗粒通量转移到较小尺寸的类别，因此它们在中水食物网中的重要性可能会更加广泛。