Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing, 210024, PR China.
Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing, 210024, PR China.
Environ Res. 2022 Nov;214(Pt 2):113913. doi: 10.1016/j.envres.2022.113913. Epub 2022 Jul 14.
Understanding how the structures and functions of bacterial and microeukaryotic communities vary within cross-sections will improve managements aimed at restoring river ecological functions. However, no comprehensive investigation has examined how microbial community characteristics vary within cross-sections, which makes the accurate calculation and prediction of microbial metabolic processing of substances in rivers difficult. Here, the distributions, co-occurrence networks, and assemblies of bacterial and microeukaryotic communities and their feedback to nitrogen transformation in cross-sections of the Yangtze River were studied by coupling ecological theory, biogeochemistry, and DNA meta-barcoding methods. The study found that depth in cross-sections was the primary driving factor regulating the composition of sediment bacterial and microeukaryotic communities. Co-occurrence network analysis indicated that the effect of bacteria on the co-occurrence network decreased and the network become more simplified and instability with depth in river cross-sections. Quantified using the β-nearest taxon index, the H2 layer sediment (depth 10-20 m) displayed the largest variation in selection processes for microbial assemblies, while homogeneous selection and homogenizing dispersal contributed most to the bacterial and microeukaryotic assemblies in the H3 layer (depth >20 m). Cross-sectional depth and denitrification genes had a significant quadratic correlation, with the highest microbial nitrogen-removal potential occurring in the H2 layer sediment. Structural equation models showed that the sediment nitrogen distributions were regulated by distinct environmental pathways at different depths, and that the H2 layer sediment was primary driven by bacterial community. In this layer, river cross-sectional depth influenced nitrogen transformation by regulating the distribution of sediment particle sizes, which then influenced the assembly of the multitrophic microbial communities. This study will improve river management by clarifying the importance of cross-sectional depth to the ecological function of rivers.
了解细菌和微型真核生物群落的结构和功能如何在河流横截面上变化，将有助于改善旨在恢复河流生态功能的管理措施。然而，目前还没有全面的研究来检查微生物群落特征在横截面上是如何变化的，这使得准确计算和预测河流中物质的微生物代谢处理变得困难。在这里，通过耦合生态理论、生物地球化学和 DNA 元条形码方法，研究了长江横截面上细菌和微型真核生物群落的分布、共现网络和组装及其对氮转化的反馈。研究发现，横截面上的深度是调节沉积物细菌和微型真核生物群落组成的主要驱动因素。共现网络分析表明，随着河流横截面上深度的增加，细菌对共现网络的影响减小，网络变得更加简化和不稳定。使用β最近分类单元指数量化，H2 层沉积物（深度 10-20 m）显示出微生物组装选择过程的最大变化，而同质选择和同质化扩散对 H3 层（深度>20 m）的细菌和微型真核生物组装贡献最大。横截面上的深度和反硝化基因之间存在显著的二次相关性，H2 层沉积物中微生物氮去除潜力最高。结构方程模型表明，不同深度的环境途径对沉积物氮的分布有不同的调节作用，H2 层沉积物主要受细菌群落的驱动。在这一层，河流横截面上的深度通过调节沉积物粒径的分布来影响氮转化，从而影响多营养级微生物群落的组装。本研究通过阐明横截面上的深度对河流生态功能的重要性，将改善河流管理。
