Influences of anthropogenic land use on microbial community structure and functional potentials of stream benthic biofilms

Xiaodong Qu,Wenqi Peng,Haiping Zhang,Yuhang Zhang,Min Zhang,Xiaobo Liu,Ze Ren

doi:10.1038/s41598-017-15624-x

Abstract

Stream ecosystems are the primary receivers of nutrient and organic carbon exported from terrestrial ecosystems and are profoundly influenced by the land use of the surrounding landscape. The aquatic impacts of anthropogenic land use are often first observed in stream benthic biofilms. We studied the benthic biofilms in streams flowing through forest (upstream) and anthropogenic land use (downstream) areas in southwestern China. The results showed that anthropogenic land use increased nutrient and organic carbon in both stream water and benthic biofilms, which are closely related to the differences in the microbial communities. The taxonomic dissimilarity of the communities was significantly correlated with the functional gene dissimilarity, and the upstream sites had more distinct functional genes. Network analysis showed that upstream sites had more highly connected microbial networks. Furthermore, downstream sites had higher relative abundances of anammox and denitrification suggesting stronger nitrogen removal than upstream sites. Increased nutrients in both the stream water and biofilms caused by anthropogenic land use had severe impacts on the nitrogen cycle in stream ecosystems. Downstream sites also had stronger carbon metabolism than upstream sites. This study provides insights into the influences of anthropogenic land use on microbial community structure and functions of stream benthic biofilms.

Highlights

Natural landscapes are transformed by anthropogenic activities to satisfy human needs through processes such as agriculture and urbanization[1]
The aquatic impacts of land use can often first be observed in their effects on stream benthic biofilms[9,10], which are likely linked to watershed conditions because land use significantly controls the export of carbon (C), nitrogen (N), and phosphorus (P) from catchments to aquatic ecosystems[11,12,13], potentially shifting the in situ microbial community structure and bacteria mediated processes
biofilm nitrogen (Bio-N) was positively correlated with Total nitrogen (TN), NO3−, and Total phosphorus (TP) (Table 2, P < 0.05)

Summary

Introduction

Natural landscapes are transformed by anthropogenic activities to satisfy human needs through processes such as agriculture and urbanization[1]. The aquatic impacts of land use can often first be observed in their effects on stream benthic biofilms[9,10], which are likely linked to watershed conditions because land use significantly controls the export of carbon (C), nitrogen (N), and phosphorus (P) from catchments to aquatic ecosystems[11,12,13], potentially shifting the in situ microbial community structure and bacteria mediated processes. The influences of anthropogenic land use on microbial community structures and functional potentials of stream biofilms are remain unclear. We studied the benthic biofilms in streams flowing through forests and anthropogenic land use (agriculture and urban) areas in the Erhai Lake watershed in southwestern China. We hypothesized that (1) anthropogenic land use leads to nutrient and organic carbon increase and alters microbial community structure, and (2) anthropogenic land use alters the nitrogen and carbon metabolic pathways, which are associated with the community structure and nutrient concentrations

Methods

Results

Discussion

Conclusion