How Microbial Communities Respond To Dams

There are more nitrogen cycling bacteria found in rivers that have been dammed, scientists say.

AsianScientist (Mar. 24, 2015) – As one of the most abundant types of organisms on Earth, bacterioplankton have been found existing in water almost anywhere. Extremely diverse and highly dynamic, their activities directly influence water conditions and biogeochemical cycling.

Bacterioplankton communities also undergo significant shifts in composition or function in response to the environmental variations. The environmental changes from the construction of river dams can greatly affect the aquatic microorganisms living in the reservoir systems. However, most research to date has focused on community structure; knowledge regarding microbial function in response to dam building is still lacking.

In order to screen the community structure and its function, a team of researchers from the Institute of Hydrobiology of the Chinese Academy of Sciences and the University of Oklahoma investigated the response of bacterioplankton to the Three Gorges Dam.

Focusing on bacterioplankton collected from the Xiangxi River, the team used metagenomics to study the function of bacterial communities. The results indicated that backwater and riverine bacterioplankton communities, representing communities with and without direct dam effects respectively, were both taxonomically and functionally different.

In the riverine area, there were many more nitrogen cycling Betaproteobacteria (e.g., Limnohabitans) and a higher abundance of functional genes and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology groups involved in nitrogen cycling. This suggests a higher level of bacterial activity involved in generating more nitrogenous nutrients for the growth of phytoplankton.

Although different methods used in describing the microbial diversity did not necessarily give identical results, the results suggest that the culture-independent approaches used in this study detected similar bacterioplankton patterns along the Xiangxi River.

Moreover, all of the diversity revealed by the different methods significantly correlated with the environmental factors. The results also confirmed that environmental filtering was one of the major processes driving the bacterioplankton community changes in the Xiangxi River.

The article can be found at: Yan et al. (2015) Impacts of the Three Gorges Dam on Microbial Structure and Potential Function.

—–

Source: Chinese Academy of Sciences; Photo: Harvey Barrison/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Asian Scientist Magazine is an award-winning science and technology magazine that highlights R&D news stories from Asia to a global audience. The magazine is published by Singapore-headquartered Wildtype Media Group.

Related Stories from Asian Scientist