Seasonal Variations in Microbial Community Structure and Function in the Waters Along the Yangtze-to-Huaihe Water Diversion Project According to Metagenomics.

Water diversion projects can alleviate the uneven spatiotemporal distribution of water resources, but they may also impact functions of aquatic ecosystems in the waters along the route. Despite their importance, the temporal and spatial changes in multi-domain microbial community structure and function along the route remain poorly understood. Metagenomics was employed to investigate the community structure and function of bacteria, archaea, and fungi in the aquatic environments along the Yangtze-to-Huaihe water diversion project in winter and summer seasons. The results showed that seasonal variations may drive a trade-off in the species diversity of bacterial and fungal communities. Seasonal variations altered microbial communities (especially for the bacteria), and exerted a greater influence on community structure than spatial factors. Microbial community composition was more sensitive to seasonal fluctuations than functional genes. The species spatial turnover played a dominant role in shaping microbial communities (especially for winter) in both seasons. Archaea, bacteria, fungi and KEGG functional genes all exhibited a positive correlation with some environmental factors in summer but not in winter. PLS-SEM indicated that water quality and microbial composition directly significantly impacted functional genes. This study offers a theoretical basis for maintaining the stability of water ecological microorganisms in water transfer projects.