Ecosystem functioning, i.e. the transfer of material through a system, supports the ecosystem services deep-sea sediments provide, including carbon sequestration, nutrient regeneration, and climate regulation. To date, seven studies globally have researched how various benthic groups contribute to organic matter degradation in abyssal sediments through stable isotope tracer experiments, of which only one in the Atlantic (at the Porcupine Abyssal Plain or PAP). To expand the limited knowledge base on abyssal ecosystem functioning, we performed stable isotope experiments in the Cabo Verde Abyssal Basin (CVAB, tropical North-East Atlantic). The Cabo Verde marine region is an oceanographically interesting region with complex currents, resulting in strong gradients of productivity and unique ecological characteristics. We conducted 2-day incubations with organic substrate (lyophilised diatom culture) labelled with C and N stable isotopes through five benthic lander deployments to 4,200 m in an area presumed mesotrophic. We assessed sediment community oxygen consumption (SCOC), dissolved inorganic carbon (DIC) production, nutrient fluxes, and label incorporation into bacteria, large Foraminifera (>300 μm), meiobenthos, and macrofauna. Results were specifically compared across the Atlantic basin to the eutrophic PAP for which all the same system components were reported (). At CVAB, bacteria and meiobenthos dominated phytodetritus processing (91% and 8%, respectively), in contrast to PAP where macrofauna dominated (98%). Phytodetritus remineralisation was two to three times lower at CVAB compared to PAP, most likely due to the low abundance of fast responding macrofauna. However, overall phytodetritus processing efficiency at CVAB was four times greater compared to PAP. Our results support a mesotrophic regime at the CVAB lander site, and provide a unique first insight into ecosystem functioning of tropical (low-latitude) abyssal systems in the Atlantic Ocean. A better understanding of abyssal ecosystem functioning in various ocean regions, to which this study contributes, provides insight into main regulators of abyssal communities and thus may have implications for our understanding of abyssal systems under future climate scenarios.

中文翻译：

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佛得角深渊盆地（热带东北大西洋）原位底栖群落对植物碎屑脉冲的反应


生态系统功能，即物质通过系统的转移，支持深海沉积物提供的生态系统服务，包括碳封存、养分再生和气候调节。迄今为止，全球已有七项研究通过稳定同位素示踪实验研究了各种底栖类群如何促进深海沉积物中的有机物降解，其中只有一项在大西洋（豪猪深海平原或 PAP）。为了扩展关于深海生态系统功能的有限知识库，我们在佛得角深海盆地（CVAB，热带东北大西洋）进行了稳定同位素实验。佛得角海洋区域是一个海洋学上有趣的区域，具有复杂的海流，导致生产力梯度很大和独特的生态特征。我们通过五个底栖着陆器部署到 4,200 m 的假定中营养区域，用标有 C 和 N 稳定同位素的有机基质（冻干硅藻培养物）进行了 2 天的培养。我们评估了沉积物群落耗氧量 (SCOC)、溶解无机碳 (DIC) 产生、养分通量以及细菌、大型有孔虫 (>300 μm)、小型底栖动物和大型动物的标签掺入。将大西洋盆地的结果与报告了所有相同系统组件的富营养化 PAP 的结果进行了专门比较 ()。在 CVAB 中，细菌和小型底栖动物在植物碎屑处理中占主导地位（分别为 91% 和 8%），而 PAP 中大型动物占主导地位（98%）。与 PAP 相比，CVAB 的植物碎屑再矿化率低两到三倍，这很可能是由于快速反应的大型动物群的丰度较低。然而，CVAB 的总体植物碎屑处理效率是 PAP 的四倍。 我们的结果支持 CVAB 着陆器站点的中营养状况，并为大西洋热带（低纬度）深海系统的生态系统功能提供了独特的第一视角。这项研究有助于更好地了解不同海洋区域的深海生态系统功能，深入了解深海群落的主要调节者，从而可能对我们理解未来气候情景下的深海系统产生影响。