Submesoscale eddies and fronts are important components of oceanic mixing and energy fluxes. These phenomena occur in the surface ocean for a period of several days, on scales between a few hundred meters and few tens of kilometers. Remote sensing and modeling suggest that eddies and fronts may influence marine ecosystem dynamics, but their limited temporal and spatial scales make them challenging for observation and in situ sampling. Here, the study of a submesoscale filament in summerly Arctic waters (depth 0–400 m) revealed enhanced mixing of Polar and Atlantic water masses, resulting in a ca. 4 km wide and ca. 50 km long filament with distinct physical and biogeochemical characteristics. Compared to the surrounding waters, the filament was characterized by a distinct phytoplankton bloom, associated with depleted inorganic nutrients, elevated chlorophyll a concentrations, as well as twofold higher phyto- and bacterioplankton cell abundances. High-throughput 16S rRNA gene sequencing of bacterioplankton communities revealed enrichment of typical phytoplankton bloom-associated taxonomic groups (e.g., Flavobacteriales) inside the filament. Furthermore, linked to the strong water subduction, the vertical export of organic matter to 400 m depth inside the filament was twofold higher compared to the surrounding waters. Altogether, our results show that physical submesoscale mixing can shape distinct biogeochemical conditions and microbial communities within a few kilometers of the ocean. Hence, the role of submesoscale features in polar waters for surface ocean biodiversity and biogeochemical processes need further investigation, especially with regard to the fate of sea ice in the warming Arctic Ocean.

中文翻译：

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亚尺度物理化学动力学在时空上直接塑造浮游细菌群落结构

亚尺度涡旋和前沿是海洋混合和能量通量的重要组成部分。这些现象在表层海洋中持续数天，尺度在几百米到几十公里之间。遥感和建模表明，涡流和锋面可能会影响海洋生态系统动力学，但它们有限的时空尺度使它们对观测和原位采样具有挑战性。在这里，对夏季北极水域（深度 0-400 米）中亚中尺度细丝的研究表明，极地和大西洋水团的混合增强，导致约。4 公里宽，约。50 公里长的细丝，具有明显的物理和生物地球化学特征。与周围水域相比，长丝的特点是明显的浮游植物大量繁殖，与枯竭的无机养分有关，a浓度，以及两倍高的浮游植物和浮游细菌细胞丰度。浮游细菌群落的高通量 16S rRNA 基因测序揭示了典型的浮游植物水华相关分类群（如黄杆菌目）的富集) 灯丝内部。此外，与强烈的水俯冲有关，与周围水域相比，长丝内部 400 m 深度的有机物质垂直输出高两倍。总而言之，我们的结果表明，物理亚中尺度混合可以在海洋几公里内形成不同的生物地球化学条件和微生物群落。因此，极地水域的亚中尺度特征对表层海洋生物多样性和生物地球化学过程的作用需要进一步研究，特别是在变暖的北冰洋中海冰的命运方面。