PDF(Pubmed)
Abstract：
Floodplains play essential roles in the ecological functions of regional environments. The merging and coalescence of bacterial communities in aquatic environments results in periodic patterns driven by regular hydrological activities, which may, in turn, influence ecological activities. However, the degree of bacterial community coalescence in the lateral and vertical directions as well as the underlying hydrological mechanism of floodplain ecosystems is poorly understood. Therefore, we investigated the spatiotemporal patterns and coalescence processes of planktonic and sedimentary bacterial communities during normal and high-water periods in a floodplain ecosystem of the Yellow River source region. We classified bacterial operational taxonomic units (OTUs) based on 16S rRNA gene sequencing, and quantified community coalescence by calculating the proportions of overlapping OTUs, the contributions of upstream sources to downstream sinks, and positive/negative cohesion. The results revealed major differences in the composition and diversity of planktonic and sedimentary bacterial communities. Bacterial community diversity in the high-water period was higher than in the normal period. Laterally, hydrological connectivity promoted the immigration and coalescence of bacterial communities to oxbow lakes in both the mainstream and tributaries, with the coalescence degree of planktonic bacteria (2.9%) higher than that of sedimentary bacteria (1.7%). Vertically, the coalescence degree of mainstream planktonic and sedimentary bacterial communities was highest, reaching 2.9%. Co-occurrence network analysis revealed that hydrological connectivity increased the complexity of the bacterial network and enhanced the coalescence of keystone species to oxbow lakes. Furthermore, community coalescence improved the competitiveness and dispersal of bacterial communities. This study demonstrated that coalescence of bacterial communities is driven by hydrological connectivity in a floodplain ecosystem. Further studies should investigate the processes of bacterial community coalescence in floodplains in more detail, which could provide new approaches for environmental protection and ecological function preservation.
摘要：
洪泛区在区域环境的生态功能中起着至关重要的作用。水生环境中细菌群落的合并和合并导致由常规水文活动驱动的周期性模式，可能，反过来,影响生态活动。然而,细菌群落在横向和垂直方向上的聚结程度以及洪泛区生态系统的潜在水文机制知之甚少。因此,我们调查了黄河源区洪泛区生态系统在正常和高水位期间浮游和沉积细菌群落的时空格局和聚结过程。我们根据16SrRNA基因测序对细菌操作分类单位（OTU）进行分类，并通过计算重叠OTU的比例来量化社区合并，上游来源对下游汇的贡献，和积极/消极的凝聚力。结果表明，浮游和沉积细菌群落的组成和多样性存在重大差异。高水时期的细菌群落多样性高于正常时期。横向,水文连通性促进了细菌群落向主流和支流牛弓湖的迁移和合并，浮游细菌的聚结程度（2.9％）高于沉积细菌的聚结程度（1.7％）。垂直,主流浮游和沉积细菌群落的聚结程度最高，达到2.9%。共现网络分析显示，水文连通性增加了细菌网络的复杂性，并增强了梯形物种与牛弓湖的结合。此外，群落聚结提高了细菌群落的竞争力和分散性。这项研究表明，细菌群落的合并是由洪泛区生态系统中的水文连通性驱动的。进一步的研究应该更详细地研究洪泛区细菌群落合并的过程，为环境保护和生态功能保护提供了新的途径。
