Profiling of Sediment Microbial Community in Dongting Lake before and after Impoundment of the Three Gorges Dam.

Wei Huang,Xia Jiang

doi:10.3390/ijerph13060617

Abstract

The sediment microbial community in downstream-linked lakes can be affected by the operation of large-scale water conservancy projects. The present study determined Illumina reads (16S rRNA gene amplicons) to analyze and compare the bacterial communities from sediments in Dongting Lake (China) before and after impoundment of the Three Gorges Dam (TGD), the largest hydroelectric project in the world. Bacterial communities in sediment samples in Dongting Lake before impoundment of the TGD (the high water period) had a higher diversity than after impoundment of the TGD (the low water period). The most abundant phylum in the sediment samples was Proteobacteria (36.4%–51.5%), and this result was due to the significant abundance of Betaproteobacteria and Deltaproteobacteria in the sediment samples before impoundment of the TGD and the abundance of Gammaproteobacteria in the sediment samples after impoundment of the TGD. In addition, bacterial sequences of the sediment samples are also affiliated with Acidobacteria (11.0% on average), Chloroflexi (10.9% on average), Bacteroidetes (6.7% on average), and Nitrospirae (5.1% on average). Variations in the composition of the bacterial community within some sediment samples from the river estuary into Dongting Lake were related to the pH values. The bacterial community in the samples from the three lake districts of Dongting Lake before and after impoundment of the TGD was linked to the nutrient concentration.

Highlights

The operation of large-scale water conservancy projects can change the natural hydrological cycles and sediment translocation processes in downstream linked lakes [1,2]
The bacterial 16S rRNA gene sequences were obtained from sediment samples in different locations during the high and low water periods
Diversity concerns both taxon richness and evenness, and the results demonstrated that both parameters in most of sediments (HS3–HS10) from high water period were higher than sediments (LS3–LS10) from low water period (Figure 2)

Summary

Introduction

The operation of large-scale water conservancy projects can change the natural hydrological cycles and sediment translocation processes in downstream linked lakes [1,2]. The damming of rivers has had a significant global impact on natural water resources [3], as impoundment of dams can affect the water environments, i.e., physical, chemical, and biological characteristics, as well as the hydrology of neighboring lakes or rivers. The Three Gorges Dam (TGD) is on the lower section of the upper reaches of the Yangtze River, and is the largest hydroelectric project in the world. The project has played a significant role in controlling frequent catastrophic floods downstream, generating hydropower (18,200 MW), water storage (12.4 billion m3 , 2003), and improving navigation at the upper reaches of the Yangtze

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Results

Conclusion