Plankton respiration (R) is a key factor governing the ocean carbon cycle. However, although the ocean supports respiratory activity throughout its entire volume, to our knowledge there are no studies that tackle both the spatial and temporal variability of respiration in the dark ocean and its dependence on organic carbon sources. Here, we have studied the variability of epipelagic and mesopelagic R via the enzymatic activity of the electron transport system (ETS) in microbial communities, along two zonal sections (21°N and 26°N) extending from the northwest African coastal upwelling to the open-ocean waters of the North Atlantic subtropical gyre, during the fall 2002 and the spring 2003. Overall, integrated R in epipelagic (R_epi; 0–200 m) waters, was similar during the two periods, while integrated mesopelagic respiration (R_meso; 200–1000 m) was >25% higher in the fall. The two seasons, however, exhibited contrasting zonal and meridional patterns of ETS distribution in the water column, largely influenced by upwelling effects and associated mesoscale variability. Multiple linear regression between average R and average concentrations of dissolved organic carbon (DOC) and slow-sinking (suspended) particulate organic carbon (POC_sus) indicates that POC_sus is the main contributor to R_meso, supporting previous results in the same area. R_meso exceeded satellite-derived net primary production (NPP) at all stations except at the most coastal ones, with the imbalance increasing offshore. Moreover, the export flux of sinking POC collected at 200 m with sediment traps, represented on average less than 6% of the NPP. All this indicates that R_meso depends largely on small particles with low sinking rates, which would be laterally advected at mid water depths from the continental margin toward the open ocean, or transported by mesoscale features from the surface to the mesopelagic ocean, providing support to inferences from modeling studies in the region.

浮游生物呼吸（R）是控制海洋碳循环的关键因素。但是，尽管海洋在整个体积上都支持呼吸活动，但据我们所知，尚无研究解决暗海中呼吸的时空变化及其对有机碳源的依赖性。在这里，我们研究了沿微生物群落电子传输系统（ETS）的酶活性，沿着从非洲西北部沿海向上延伸到两个纬向区带（21°N和26°N）的上表皮和中生R的变化。 2002年秋季和2003年春季期间总北大西洋亚热带环流，开放式海洋水域，集成的R epipelagic（R_外延; 在这两个时期中，0-200 m）的水量相似，而秋季的中近呼吸综合呼吸（R _meso ; 200-1000 m）高出25％以上。然而，这两个季节在水柱中表现出不同的ETS纬向和经向分布格局，这在很大程度上受到上升流效应和相关的中尺度变化的影响。平均R和溶解有机碳（DOC）的平均浓度与缓慢下沉（悬浮）的颗粒有机碳（POC _sus）之间的多元线性回归表明，POC _sus是R _meso的主要贡献者，支持了同一地区的先前结果。[R_中观除最沿海的电台外，所有电台的卫星初次净初级生产（NPP）都超过了卫星，离岸失衡加剧。此外，下沉的POC的出口通量在200 m处用沉积物捕集器收集，平均不到NPP的6％。所有这些表明，R_细观主要依赖于低下沉率的小颗粒，这些细小颗粒将在从大陆边缘向大洋的中等水深处横向平移，或者通过中尺度特征从地表运至中弹性海，从而为下沉提供支持。来自该地区建模研究的推论。