Disentangling ecological mechanisms behind dredging is meaningful to implement environmental policy for improving water quality. However, environmental adaptation and community assembly processes of bacterioplankton in response to dredging disturbance are poorly understood. Based on Illumine MiSeq sequencing and multiple statistical analyses, we estimated interactions, functions, environmental breadths, phylogenetic signals, phylogenetic clustering, and ecological assembly processes of bacterioplankton community before and after dredging. We found distinct change in community composition, comparable decreases in diversity, functional redundancy and conflicting interaction, relatively low phylogenetic clustering, and relatively weak environmental adaptation after dredging. The bacterioplankton community assembly was affected by both stochastic and deterministic processes before dredging, but dominated by stochasticity after dredging. Sediment total phosphorus was a decisive factor in balancing determinism and stochasticity for bacterioplankton community assembly before and after dredging. Consequently, taxonomic and phylogenetic α-diversities of bacterioplankton exhibited higher contributions to the water trophic level represented by chlorophyl α before dredging than afterwards. Our results emphasized bacterioplankton in response to environmental changes caused by dredging, with nutrient loss and ecological drift playing important roles. These findings extend knowledge of contribution of bacterioplankton diversity to water trophic level and decipher mechanisms of bacterioplankton diversity maintenance in response to dredging, which is useful for guiding mitigation of cyanobacterial blooms.

理清疏浚背后的生态机制对于实施改善水质的环境政策具有重要意义。然而，人们对浮游细菌响应疏浚干扰的环境适应和群落组装过程知之甚少。基于Illumine MiSeq测序和多重统计分析，我们估计了疏浚前后浮游细菌群落的相互作用、功能、环境广度、系统发育信号、系统发育聚类和生态组装过程。我们发现，疏浚后群落组成发生明显变化，多样性下降，功能冗余和相互冲突，系统发育聚类相对较低，环境适应性相对较弱。疏浚前浮游细菌群落集聚受到随机性和确定性过程的影响，疏浚后以随机性为主。沉积物总磷是平衡疏浚前后浮游细菌群落聚集的决定性和随机性的决定性因素。因此，浮游细菌的分类学和系统发育 α 多样性对疏浚前叶绿素 α 所代表的水营养水平的贡献高于疏浚之后。我们的研究结果强调了浮游细菌对疏浚引起的环境变化的反应，其中养分流失和生态漂移起着重要作用。