Marine planktonic bacteria and archaea commonly exhibit pronounced seasonal succession in community composition. But the existence of seasonality in their assembly processes and between‐domain differences in underlying mechanism are largely unassessed. Using a high‐coverage sampling strategy (including single sample for each station during four cruises in different seasons), 16S rRNA gene sequencing, and null models, we investigated seasonal patterns in the processes governing spatial turnover of bacteria and archaea in surface coastal waters across a sampling grid over ~300 km in the East China Sea. We found that archaea only bloomed in prokaryotic communities during autumn and winter cruises. Seasonality mostly overwhelmed spatial variability in the compositions of both domains. Bacterial and archaeal communities were dominantly governed by deterministic and stochastic assembly processes, respectively, in autumn cruise, probably due to the differences in niche breadths (bacteria < archaea) and relative abundance (bacteria > archaea). Stochasticity dominated assembly mechanisms of both domains but was driven by distinct processes in winter cruise. Determinism‐dominated assembly mechanisms of bacteria rebounded in spring and summer cruises, reflecting seasonal variability in bacterial community assembly. This could be attributed to seasonal changes in bacterial niche breadths and habitat heterogeneity across the study area. There were seasonal changes in environmental factors mediating the determinism‐stochasticity balance of bacterial community assembly, holding a probability of the existence of unmeasured mediators. Our results suggest contrasting assembly mechanisms of bacteria and archaea in terms of determinism‐vs.‐stochasticity pattern and its seasonality, highlighting the importance of seasonal perspective on microbial community assembly in marine ecosystems.

中文翻译：

---

沿海水域中细菌和古细菌的群落聚集受不同机制的支配：一个季节性的观点。

海洋浮游细菌和古细菌通常在群落组成上表现出明显的季节性演替。但是，在组装过程中是否存在季节性变化以及潜在机制之间的域间差异在很大程度上未被评估。使用高覆盖率采样策略（包括在不同季节进行的四次航行中每个站点的单个采样），16S rRNA基因测序和无效模型，我们研究了控制整个表层沿海水域中细菌和古细菌的空间周转过程中的季节性模式东海约300公里处的采样网格。我们发现古细菌仅在秋季和冬季巡游期间在原核生物群落中开花。在两个领域的构成中，季节性大多使空间变异性不堪重负。在秋季航行中，细菌和古细菌群落分别受确定性和随机装配过程的支配，这可能是由于利基宽度（细菌<古细菌）和相对丰度（细菌>古细菌）的差异。随机性主导了两个领域的组装机制，但受到冬季航行中不同过程的驱动。确定性主导的细菌装配机制在春季和夏季航行中反弹，反映了细菌群落装配的季节性变化。这可能归因于整个研究区域细菌生态位宽度和生境异质性的季节性变化。环境因素的季节性变化介导了细菌群落装配体的确定性-随机性平衡，从而有可能存在无法测量的介质。