Eutrophication as a driver of microbial community structure in lake sediments

Abstract

Summary Lake sediments are globally important carbon sinks. Although the fate of organic carbon in lake sediments depends significantly on microorganisms, only few studies have investigated controls on lake sedimentary microbial communities. Here we investigate the impact of anthropogenic eutrophication, which affects redox chemistry and organic matter (OM) sources in sediments, on microbial communities across five lakes in central Switzerland. Lipid biomarkers and distributions of microbial respiration reactions indicate strong increases in aquatic OM contributions and microbial activity with increasing trophic state. Across all lakes, 16S rRNA genes analyses indicate similar depth‐dependent zonations at the phylum‐ and class‐level that follow vertical distributions of OM sources and respiration reactions. Yet, there are notable differences, such as higher abundances of nitrifying Bacteria and Archaea in an oligotrophic lake. Furthermore, analyses at the order‐level and below suggest that changes in OM sources due to eutrophication cause permanent changes in bacterial community structure. By contrast, archaeal communities are differentiated according to trophic state in recently deposited layers, but converge in older sediments deposited under different trophic regimes. Our study indicates an important role for trophic state in driving lacustrine sediment microbial communities and reveals fundamental differences in the temporal responses of sediment Bacteria and Archaea to eutrophication.

Total Arsenic, pH, and Sulfate Are the Main Environmental Factors Affecting the Microbial Ecology of the Water and Sediments in Hulun Lake, China

“…The physical and chemical indexes such as water temperature, pH, dissolved oxygen, and conductivity were determined using a three-channel analyzer (portable) (WTW, Germany), and the remaining environmental factors were determined in the laboratory according to standard methods ( Fang et al, 2015 ; Han et al, 2020 ) ( Supplementary Table 2 ).…”

Reply on RC1

“…(4) There is also essential information missing in the methods such as DNA extraction from the sediment, bioinformatics, and DNA sequencing. It seems that this part is instead presented in a manuscript that is in press (Han et al 2020), however there is no need to present this data as results for this manuscript. I also think it might be misleading to do so and the authors better double-check the journal guidelines for what is acceptable.…”

“…I also think it might be misleading to do so and the authors better double-check the journal guidelines for what is acceptable. Instead the authors can mention relevant findings from Han et al (2020) C3…”

“…Printer-friendly version Discussion paper in the discussion. If the results are first presented in Han et al (2020) then it should not be presented again as new results for this manuscript. Furthermore, Han et al (2020) is missing in the reference list so there is no way for the reviewers to read these methods or results.…”

“…To be clear: all sequencing data from tubes and macrofauna, and all functional gene data, are new to this study. We only include a small subset of published background sediment 16S rRNA gene from Han et al (2020) for comparison. These background sediment samples were extracted and sequenced using the same method that we applied in this study.…”