Description: Groundwater ecosystems are globally widespread yet still poorly understood. We investigated the microbiology of 〉100 groundwater samples from 90 monitoring wells (〈250m depth) located in 14 aquifers in the Canadian Prairie. This dataset contains the nucleotide sequences and taxonomy of archaeal 16S rRNA gene amplicons retrieved from groundwater samples of aquifers in the Canadian Prairie, collected between 2015 and 2020. The study area comprised 14 major aquifers and a geographic area of ~210.000 km2. The goal of the study was to understand the links between the biogeochemistry and microbial ecology of groundwater ecosystems in diverse geological settings on a broad spatial scale. Details concerning DNA extraction, sequencing and sequence analyses can be found in the associated publication by Ruff et al. 2023.

Description: Emission of the greenhouse gas methane from the seabed is globally controlled by marine aerobic and anaerobic methanotrophs gaining energy via methane oxidation. However, the processes involved in the assembly and dynamics of methanotrophic populations in complex natural microbial communities remain unclear. Here we investigated the development of a methanotrophic microbiome following subsurface mud eruptions at Håkon Mosby mud volcano (1250 m water depth). We analyzed surface and subsurface sediment samples across HMMV mud flows from most recently discharged subsurface muds towards old consolidated muds as well as one reference site located approximately 0.5 km outside of the HMMV. Surface sediment samples (0-20 cm) were recovered either by TV-guided Multicorer or by push cores. Subsurface sediments of all zones (〉2 m below sea floor) were obtained in by gravity corer. After recovery, sediments were immediately subsampled in a refrigerated container (0°C) and further processed for biogeochemical analyses or preserved at -20°C for later DNA analyses. Our study show that freshly erupted muds hosted deep-subsurface communities, which were dominated by Bathyarchaeota, Atribacteria and Chloroflexi. Methanotrophy was initially limited to a thin surface layer of Methylococcales populations consuming methane aerobically. With increasing distance to the eruptive center, anaerobic methanotrophic archaea, sulfate-reducing Desulfobacterales and thiotrophic Beggiatoaceae developed, and their respective metabolic capabilities dominated the biogeochemical functions of the community. Microbial richness, evenness, and cell numbers of the entire microbial community increased up to tenfold within a few years downstream of the mud flow from the eruptive center. The increasing diversity was accompanied by an up to fourfold increase in sequence abundance of relevant metabolic genes of the anaerobic methanotrophic and thiotrophic guilds. The communities fundamentally changed in their structure and functions as reflected in the metagenome turnover with distance from the eruptive center, and this was reflected in the biogeochemical zonation across the mud volcano caldera. The observed functional succession provides a framework for the response time and recovery of complex methanotrophic communities after disturbances of the deep-sea bed.