Abstract

Bacterial communities play an important role in the biogeochemical cycle in reservoir ecosystems. However, the dynamic changes in both planktonic and sediment bacterial communities in a highly regulated dam reservoir remain unclear. This study investigated the temporal distribution patterns of bacterial communities in a transition section of the Three Gorges Reservoir (TGR) using Illumina MiSeq sequencing. Results suggested that in comparison to the planktonic bacteria, sediment bacteria contributed more to the reservoir microbial communities, accounting for 97% of the 7434 OTUs. The Shannon diversity index in the water (3.22~5.68) was generally lower than that in the sediment (6.72~7.56). In the high water level period (January and March), Proteobacteria, Actinobacteria, Cyanobacteria, and Firmicutes were the most abundant phyla, whereas in the low water level period (May, July, and September), the dominant phyla were Proteobacteria, Actinobacteria, and Bacteroidetes. Sediment samples were dominated by Proteobacteria, Chloroflexi, and Acidobacteria. Principal coordinate analysis of the bacterioplankton communities showed greater sensitivity to monthly changes than that of the sediment bacterial communities. Network analysis suggested that in comparison to planktonic bacterial communities, sediment bacterial communities were more complex and stable. The linear relationship between the CH₄/CO₂ ratio, water level, and relative abundance of methanotrophs highlighted the potential methane-oxidizing process in the mid-part of the TGR. Moreover, the potential impact of dam regulation on the bacterial communities was revealed by the significant relationship between abundant phyla and the inflow of the TGR.

Key points

• Bacterioplankton communities showed great sensitivity to monthly changes.

• Potential methane-oxidizing process was revealed in this representative area.

• Water inflow regulated by dam has significant effects on dominant bacterioplankton.

中文翻译：

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三峡水库中部高度调节水坝下浮游细菌和沉积物细菌群落的变化

摘要

细菌群落在水库生态系统的生物地球化学循环中起着重要作用。但是，在高度调节的水库中浮游细菌和沉积细菌群落的动态变化仍不清楚。本研究使用Illumina MiSeq测序方法研究了三峡水库（TGR）过渡段细菌群落的时间分布格局。结果表明，与浮游细菌相比，沉积物细菌对储层微生物群落的贡献更大，占7434个OTU的97％。水中的香农多样性指数（3.22〜5.68）普遍低于沉积物的香农多样性指数（6.72〜7.56）。在高水位时期（1月和3月），变形杆菌，放线菌，蓝细菌和Firmicutes是最多的门，而在水位低的时期（5月，7月和9月），主要的门是变形杆菌，放线菌和拟杆菌。沉积物样品以变形杆菌，弯曲菌和酸性菌为主。浮游细菌群落的主坐标分析显示，对每月变化的敏感性高于沉积物细菌群落。网络分析表明，与浮游细菌群落相比，沉积物细菌群落更为复杂和稳定。CH ₄之间的线性关系/ CO ₂比，水位和甲烷营养菌的相对丰度突出了TGR中部的潜在甲烷氧化过程。此外，水坝调节对细菌群落的潜在影响通过丰富的门脉与TGR流入之间的显着关系揭示出来。

关键点

•浮游细菌群落对每月变化表现出极大的敏感性。

•在该代表性地区发现了潜在的甲烷氧化过程。

•大坝调节的水流入对优势浮游细菌有重要影响。