Response of prokaryotic, eukaryotic and algal communities to heavy rainfall in a reservoir supplied with reclaimed water

The global climate change made the heavy rainfall happen more frequently, and the non-point source pollution caused by it would exacerbate the risk to the water ecological environment. In this study, we took a reservoir (Shahe reservoir, Beijing, China) supplied with reclaimed water as an exapmle to investigate how spatiotemporal changes in the quantity and diversity of prokaryotic, eukaryotic, and algal communities respond to heavy rainfall. Results showed that heavy rainfall could directly impact the composition of the prokaryotic community by introducing amounts of runoff closely associated bacterium especially for the human potential pathogens such as Aliarcobacter, Aeromonas and Pseudomonas in the Shahe reservoir area. While the eukaryotic community was rather stable, and the development and changes in algal communities occurred in the last few days after heavy rainfall. The microbial source tracking through FEAST indicated that Nansha river (S) was the major contributor to the development of all the three concerned communities in the reservoir. The co-occurrence analysis showed that the modules with the highest cumulative abundance in each community were all strongly and positively connected with Chl-a, pH, turbidity, COD and TOC, but negatively correlated with NO3-N (p < 0.01). The network analysis showed that the eukaryotes played a key role in the interaction network among the three communities, and were more likely to interact with algae and prokaryotes. It was suggested that the controlling of human potential pathogens associated with prokaryotic community should be emphasized at the beginning of the heavy rainfall, but the prevention of the eutrophication bloom should be another focus after the heavy rainfall. This study provided valuable information concerning the role of heavy rainfall on the water ecological environment from the perspective of microbial community.

Automated summary

Global climate change leads to more frequent heavy rainfall, which causes non-point source pollution and exacerbates risks to the water ecological environment. This study investigated the response of prokaryotic, eukaryotic, and algal communities to heavy rainfall in the Shahe reservoir in Beijing, China. The results showed that heavy rainfall directly impacted the composition of the prokaryotic community and introduced potential human pathogens into the reservoir. The eukaryotic community remained stable, while changes in algal communities occurred a few days after heavy rainfall. Microbial source tracking revealed that the Nansha river was the major contributor to the development of all three communities in the reservoir. Co-occurrence analysis and network analysis highlighted the importance of eukaryotes in the interaction network among the three communities. The findings suggest that controlling human potential pathogens associated with the prokaryotic community should be a priority during heavy rainfall, while preventing eutrophication blooms should be addressed afterwards.