Microbial subnetworks related to diel O2 fluxes within geochemically distinct freshwater wetlands.

O2 concentrations often fluctuate over diel timescales within wetlands, driven by temperature, sunlight, photosynthesis, and respiration. These daily fluxes have been shown to impact biogeochemical transformations (e.g. denitrification), which are mediated by the residing microbial community. However, little is known about how resident microbial communities respond to diel dramatic physical and chemical fluxes in freshwater wetland ecosystems. In this study, total microbial (bacterial and archaeal) community structure was only significantly related to diel time points in one out of four distinct freshwater wetlands sampled. This suggests that daily environmental shifts may influence wetlands differentially based upon the resident microbial community and specific physical and chemical conditions of a freshwater wetland. However, when exploring at finer resolutions of the microbial communities within each wetland, subcommunities within two wetlands were found to correspond to fluctuating O2 levels. Microbial taxa that were found to be susceptible to fluctuating O2 levels within these subnetworks may have intimate ties metabolism and/or diel redox cycles. This study highlights that freshwater wetland microbial communities are often stable in community structure when confronted with short-term O¬2 fluxes, however, specialist taxa may be sensitive these same fluxes.