Unidad Académica de Ecología y Biodiversidad Acuática, Institute of Marine Sciences and Limnology, National Autonomous University of Mexico, Mexico City, Mexico.
Microb Ecol. 2020 Oct;80(3):519-536. doi: 10.1007/s00248-020-01508-7. Epub 2020 May 15.
Microbial communities within oxygen minimum zones (OMZs) are crucial drivers of marine biogeochemical cycles; however, we still lack an understanding of how these communities are distributed across an OMZ. We explored vertical (from 5 to 500 m depth) and horizontal (coast to open ocean) distribution of bacterioplankton and its relationships with the main oceanographic conditions in three transects of the tropical Mexican Pacific OMZ. The distribution of the microbial diversity and the main clades changed along the transition from oxygen-rich surface water to the OMZ core, demonstrating the sensitivity of key bacterial groups to deoxygenation. The euphotic zone was dominated by Synechococcales, followed by Flavobacteriales, Verrucomicrobiales, Rhodobacterales, SAR86, and Cellvibrionales, whereas the OMZ core was dominated by SAR11, followed by SAR406, SAR324, SAR202, UBA10353 marine group, Thiomicrospirales and Nitrospinales. The marked environmental gradients along the water column also supported a high potential for niche partitioning among OMZ microorganisms. Additionally, in the OMZ core, bacterial assemblages from the same water mass were more similar to each other than those from another water mass. There were also important differences between coastal and open-ocean communities: Flavobacteriales, Verrucomicrobiales, Rhodobacterales, SAR86, and Cellvibrionales were more abundant in coastal areas, while Synechococcales, SAR406, SAR324, SAR202, UBA10353 marine group, and Thiomicrospirales were more abundant in the open ocean. Our results suggest a biogeographic structure of the bacterioplankton in this OMZ region, with limited community mixing across water masses, except in upwelling events, and little dispersion of the community by currents in the euphotic zone.
海洋氧最小层（OMZs）内的微生物群落是海洋生物地球化学循环的关键驱动因素；然而，我们仍然缺乏对这些群落如何在 OMZ 中分布的理解。我们在热带墨西哥太平洋 OMZ 的三个横截面上探索了浮游细菌的垂直（从 5 米到 500 米深度）和水平（从海岸到开阔海洋）分布及其与主要海洋条件的关系。微生物多样性的分布和主要分支在从富氧地表水到 OMZ 核心的过渡过程中发生了变化，这表明关键细菌群对脱氧的敏感性。真光层主要由聚球藻目、黄杆菌目、疣微菌目、红杆菌目、SAR86 和细胞动弯杆菌目主导，而 OMZ 核心主要由 SAR11 主导，其次是 SAR406、SAR324、SAR202、UBA10353 海洋群、硫微菌目和硝化螺旋菌目。水柱中的明显环境梯度也支持 OMZ 微生物之间具有高度的生态位分化潜力。此外，在 OMZ 核心，来自同一水体的细菌组合彼此之间比来自另一水体的组合更相似。沿海和开阔海洋群落之间也存在重要差异：黄杆菌目、疣微菌目、红杆菌目、SAR86 和细胞动弯杆菌目在沿海地区更为丰富，而聚球藻目、SAR406、SAR324、SAR202、UBA10353 海洋群和硫微菌目在开阔海洋中更为丰富。我们的结果表明，该 OMZ 区域的浮游细菌具有生物地理结构，除了上升流事件外，水团之间的群落混合有限，在真光层中，群落也很少受到洋流的分散。
