Abstract
In stratified lakes, methane-oxidizing bacteria (MOB) are strongly mitigating methane fluxes to the atmosphere by consuming methane entering the water column from the sediments. MOB communities in lakes are diverse and vertically structured, but their spatio-temporal dynamics along the water column as well as physico-chemical parameters and interactions with other bacterial species that drive the community assembly have so far not been explored in depth. Here, we present a detailed investigation of the MOB and bacterial community composition and a large set of physico-chemical parameters in a shallow, seasonally stratified, and sub-alpine lake. Four highly resolved vertical profiles were sampled in three different years and during various stages of development of the stratified water column. Non-randomly assembled MOB communities were detected in all compartments. We could identify methane and oxygen gradients and physico-chemical parameters like pH, light, available copper and iron, and total dissolved nitrogen as important drivers of the MOB community structure. In addition, MOB were well-integrated into a bacterial-environmental network. Partial redundancy analysis of the relevance network of physico-chemical variables and bacteria explained up to 84% of the MOB abundances. Spatio-temporal MOB community changes were 51% congruent with shifts in the total bacterial community and 22% of variance in MOB abundances could be explained exclusively by the bacterial community composition. Our results show that microbial interactions may play an important role in structuring the MOB community along the depth gradient of stratified lakes.
Highlights
Atmospheric concentrations of the potent greenhouse gas methane have steadily increased since the pre-industrial era from 722 to 1874 ppb.1 Freshwater lakes are significant natural methane sources, responsible for about 70% of the freshwater methane emissions (DelSontro et al, 2018; Sanches et al, 2019)
We investigated the combined effects of microbial communities and the physico-chemical environment on methane-oxidizing bacteria (MOB) community assemblies in order to improve our understanding of MOB-based ecosystem function under varying conditions
Turbidity (Turb) maxima were mostly congruent with chlorophyll a (Chl-a) throughout the water column as profiled in June and August 2013
Summary
Atmospheric concentrations of the potent greenhouse gas methane have steadily increased since the pre-industrial era from 722 to 1874 ppb. Freshwater lakes are significant natural methane sources, responsible for about 70% of the freshwater methane emissions (DelSontro et al, 2018; Sanches et al, 2019). The magnitude of the methane fluxes to the atmosphere is under strong control of anaerobic and aerobic methane oxidation (Chistoserdova, 2011; Nordi et al, 2013; Graf et al, 2018; Martinez-Cruz et al, 2018). Aerobic methane-oxidizing bacteria (MOB) oxidize up to 90% of methane within the water column of freshwater systems (Bastviken et al, 2003, 2008). They mainly belong to Gammaproteobacteria and Alphaproteobacteria and are often referred to as type I and type II MOB, respectively (Hanson and Hanson, 1996; Chistoserdova and Lidstrom, 2013; Knief, 2015)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call