In recent years, the northern Bering Sea has experienced changes in the timing of sea-ice retreat and in hydrographic conditions during the summer. The influence of these environmental changes on the diatom community has not been examined. In this study, we investigated the spatial changes in the diatom community of the northern Bering Sea during the summers of 2017 and 2018, and evaluated the effects of environmental variability on these communities. We found that the diatom cell density and diversity varied with water masses. A cluster analysis based on cell density revealed that the diatom communities were separated into four groups, and that the distributions of three of these groups were different spatially between 2017 and 2018. In the Bering Strait and the Chirikov Basin regions, the diatom communities differed between 2017 and 2018. In 2017, these diatom communities were dominated by cold-water species such as Chaetoceros gelidus and Chaetoceros spp. (subgenus Hyalochaetae), while in 2018, the community was dominated by cosmopolitan species such as Thalassionema nitzschioides and Chaetoceros spp. (subgenus Phaeoceros). NMDS and multiple regression analysis indicated that the timing of the sea-ice retreat was the most important contributor to the differences in the diatom community. In contrast, there was no year-to-year difference south of St. Lawrence Island, possibly because nutrients were depleted and phytoplankton types other than diatoms were dominant.

近年来，北部白令海经历了夏季海冰撤退时间和水文条件的变化。这些环境变化对硅藻群落的影响尚未得到检验。在这项研究中，我们调查了2017年和2018年夏季白令海北部硅藻群落的空间变化，并评估了环境变化对这些群落的影响。我们发现硅藻细胞的密度和多样性随水的质量而变化。基于细胞密度的聚类分析显示，硅藻群落分为四个组，并且这三个组的分布在2017年至2018年之间在空间上是不同的。在白令海峡和奇里科夫盆地地区，硅藻群落之间存在差异。 2017年和2018年。Chaetoceros gelidus和Chaetoceros spp。（Hyalochaetae属），而在2018年，该社区被世界性物种所控制，例如Thalassionema nitzschioides和Chaetoceros spp。（Phaeoceros亚属）。NMDS和多元回归分析表明，海冰撤退的时机是造成硅藻群落差异最重要的因素。相比之下，圣劳伦斯岛以南没有逐年差异，这可能是因为营养物质枯竭，而硅藻以外的浮游植物类型占主导。