The abyssal plain covers more than half the Earth’s surface. The main food source to abyssal ecosystems is phytodetritus, which originates from phytoplankton in the surface ocean, and thus its variability to the seafloor is a major driver of abyssal ecosystem biomass and functioning. In this study, we conducted a comparative survey on organic matter (OM) quality and quantity in abyssal plain sediments and examined the distributions of megafauna, macrofauna, meiofauna, prokaryotes, and viruses in eutrophic (39°N), oligotrophic (1°N), and ultra-oligotrophic (12°N) areas of the western Pacific. We also analyzed stable carbon and nitrogen isotopic compositions of organisms at 39°N and 1°N to assess differences in benthic abyssal food-web structures with contrasting trophic states. Sediments collected at 39°N presented highest concentrations of total organic carbon (TOC) and labile OM, and high diffusive oxygen uptake rates. By contrast, the lowest values were found at 12°N. Vertical distributions of sediment macrofauna, meiofauna, and prokaryotes matched with labile OM profiles. There were prominent differences in abundances of macro- and megafauna among stations with different OM fluxes, whereas the abundance of meiofauna and prokaryotes showed smaller differences among stations. Such differences could be explained by higher turnover rates of smaller organisms. Food-web structures of abyssal plains are likely influenced by both the type and size of primary producers in surface ocean. Our results underscore the crucial importance of OM fluxes and their compositions to the abundances and vertical profiles of labile OM and benthic biota in abyssal ecosystems.

深海平原覆盖了地球表面的一半以上。深层生态系统的主要食物来源是植根碎屑，其起源于表层海洋的浮游植物，因此其对海底的变化是深层生态系统生物量和功能的主要驱动力。在这项研究中，我们对深海平原沉积物中的有机质（OM）的质量和数量进行了比较调查，并研究了富营养化（39°N），贫营养化（1°N）中大型动物，大型动物，中型动物，原核生物和病毒的分布）和西太平洋的超贫营养地区（北纬12度）。我们还分析了39°N和1°N时生物的稳定碳和氮同位素组成，以评估底栖深渊食物网结构与营养状态相反的差异。在39°N处收集的沉积物呈现出最高的总有机碳（TOC）和不稳定的OM浓度，以及高的扩散氧气吸收率。相比之下，最低值出现在12°N处。沉积物大型动物区系，中部动物区系和原核生物的垂直分布与不稳定的OM剖面相吻合。在具有不同OM通量的站点之间，大型和大型动物的丰度存在显着差异，而中型动物和原核生物的丰度在站点之间的差异较小。这种差异可以用较小的生物体更高的周转率来解释。深海平原的食物网结构可能受表层海洋初级生产者的类型和规模的影响。