Climate change related alterations in the Arctic have influences on the marine ecosystems, in particular on phytoplankton bloom dynamics. Since phytoplankton blooms are the main provider of carbon sources to the microbial loop, the bacterial and archaeal community are affected by the changes as well. Warmer water and less sea ice can lead to an earlier onset of phytoplankton blooms and consequently also to changes in the bacterial and archaeal community dynamics throughout Arctic summers. Here, we compared the bacterial and archaeal community composition during three summers (2018, 2019, and 2021) along a transect from the Barents Sea to the Arctic Ocean north of Svalbard. We used 16S rRNA gene sequencing to investigate changes in the communities in time and space. The main results showed that, Gammaproteobacteria (Nitrincolaceae), Bacteroidia (Polaribacter), and Alphaproteobacteria (SAR11 clade 1a members) dominated the bacterial and archaeal community in the surface waters but varied in abundance patterns between the years. The variations are potentially a result of different phytoplankton bloom stages and consequently differences in the availability of carbon sources. The distinctly different deep water communities were dominated by Candidatus Nitrosopumilus, Marinimicrobia, and members of the SAR324 clade in all years. The results indicate that changes in phytoplankton bloom dynamics can influence bacterial and archaeal community and thereby marine carbon cycling in surface waters, although direct links to the effects of global warming remain uncertain.

北极气候变化相关的变化对海洋生态系统有影响，特别是对浮游植物繁殖动态的影响。由于浮游植物大量繁殖是微生物循环碳源的主要提供者，因此细菌和古细菌群落也会受到这些变化的影响。温暖的海水和较少的海冰会导致浮游植物更早开始大量繁殖，从而也会导致整个北极夏季细菌和古细菌群落动态发生变化。在这里，我们比较了三个夏季（2018 年、2019 年和 2021 年）沿着从巴伦支海到斯瓦尔巴群岛以北北冰洋的横断面的细菌和古细菌群落组成。我们使用 16S rRNA 基因测序来研究社区在时间和空间上的变化。主要结果表明，Gammaproteobacteria（Nitrincolaceae）、拟杆菌（Polaribacter）和Alphaproteobacteria（SAR11 进化枝 1a 成员）在地表水中的细菌和古细菌群落中占主导地位，但各年丰度模式各不相同。这些变化可能是浮游植物开花阶段不同以及碳源可用性差异的结果。明显不同的深水群落以Candidatus Nitrosopumilus、Marinimicrobia为主，以及所有年份的 SAR324 进化枝成员。结果表明，浮游植物大量繁殖动态的变化会影响细菌和古细菌群落，从而影响地表水中的海洋碳循环，尽管与全球变暖影响的直接联系仍不确定。