The Southern Ocean remains one of the least explored marine environments. The investigation of temporal microbial dynamics has thus far been hampered by the limited access to this remote ocean. We present here high‐resolution seasonal observations of the prokaryotic community composition during phytoplankton blooms induced by natural iron fertilization. A total of 18 seawater samples were collected by a moored remote autonomous sampler over 4 months at 5–11 day intervals in offshore surface waters (central Kerguelen Plateau). Illumina sequencing of the 16S rRNA gene revealed that among the most abundant amplicon sequence variants, SAR92 and Aurantivirga were the first bloom responders, Pseudomonadaceae, Nitrincolaceae and Polaribacter had successive peaks during the spring bloom decline, and Amylibacter increased in relative abundance later in the season. SAR11 and SUP05 were abundant prior to and after the blooms. Using network analysis, we identified two groups of diatoms representative of the spring and summer bloom that had opposite correlation patterns with prokaryotic taxa. Our study provides the first seasonal picture of microbial community dynamics in the open Southern Ocean and thereby offers biological insights to the cycling of carbon and iron, and to an important puzzling issue that is the modest nitrate decrease associated to iron fertilization.

中文翻译：

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自主采样器揭示了南大洋中原核生物的季节性动态及其与硅藻的关系。

南大洋仍然是勘探最少的海洋环境之一。迄今为止，由于对这片偏远海洋的访问受到限制，暂时微生物动力学的研究受到了阻碍。我们在此提供由天然铁肥诱导的浮游植物开花期间原核生物群落组成的高分辨率季节性观察。系泊的远程自主采样器在4个月内以5-11天的间隔在离岸地表水（中央克格伦高原）中总共采集了18个海水样品。对16S rRNA基因的Illumina测序显示，在最丰富的扩增子序列变体中，SAR92和Aurantivirga是第一个绽放响应物，假单胞菌科，硝化杆菌科和极地细菌。在春季开花下降期间出现了连续的峰值，并且在本季节后期，支链杆菌的相对丰度增加了。盛开前后SAR11和SUP05含量很高。使用网络分析，我们确定了代表春季和夏季开花的两组硅藻，它们与原核生物分类具有相反的相关模式。我们的研究提供了开阔的南大洋中微生物群落动态的第一张季节性图景，从而为碳和铁的循环以及重要的令人费解的问题提供了生物学见解，因为与铁肥有关的硝酸盐含量的适度下降。