Temporal dynamics of geothermal microbial communities in Aotearoa-New Zealand

Abstract

Microbial biogeography studies, in particular for geothermal-associated habitats, have focused on spatial patterns and/or individual sites, which have limited ability to describe the dynamics of ecosystem behaviour. Here, we report the first comprehensive temporal study of bacterial and archaeal communities from an extensive range of geothermal features in Aotearoa-New Zealand. One hundred and fifteen water column samples from 31 geothermal ecosystems were taken over a 34-month period to ascertain microbial community stability (control sites), community response to both natural and anthropogenic disturbances in the local environment (disturbed sites) and temporal variation in spring diversity across different pH values (pH 3, 5, 7, 9) all at a similar temperature of 60–70°C (pH sites). Identical methodologies were employed to measure microbial diversity via 16S rRNA gene amplicon sequencing, along with 44 physicochemical parameters from each feature, to ensure confidence in comparing samples across timeframes. Our results indicated temperature and associated groundwater physicochemistry were the most likely parameters to vary stochastically in these geothermal features, with community abundances rather than composition more readily affected by a changing environment. However, variation in pH (pH ±1) had a more significant effect on community structure than temperature (±20°C), with alpha diversity failing to adequately measure temporal microbial disparity in geothermal features outside of circumneutral conditions. While a substantial physicochemical disturbance was required to shift community structures at the phylum level, geothermal ecosystems were resilient at this broad taxonomic rank and returned to a pre-disturbed state if environmental conditions re-established. These findings highlight the diverse controls between different microbial communities within the same habitat-type, expanding our understanding of temporal dynamics in extreme ecosystems.

Antarctic geothermal soils exhibit an absence of regional habitat generalist microorganisms

“…Despite its high abundance, this MAG (Erebus-TR_bin. 23 given that Archaea are generally much more dispersal limited than Bacteria (56). Our hope is that further microbial explorations at these unique sites, with broader sampling at more areas and further metagenomic, transcriptomic, and culturing work, will help uncover the wealth of novel microorganisms present.…”

“…Finally, Antarctic geothermal regions serve as enrichment zones for thermophiles, given the vast amount of ice and snow separating regions and the extremely cold air conditions in Antarctica, resulting in little regional influence of non-thermophiles on the microbial communities present. Interestingly, past studies of thermophiles, mainly in hot spring environments, have found high niche specialization for temperature or pH, with environmental selection being the primary factor influencing community assembly and low dispersal rates between sites (20)(21)(22)(23)(24). It is unknown whether the strong winds in Antarctica are capable of overcoming the generally low dispersal rates for thermophiles at Antarctic geothermal regions.…”

CALDERA: a scientific drilling concept to unravel Connections Among Life, geo-Dynamics and Eruptions in a Rifting Arc caldera, Okataina Volcanic Centre, Aotearoa New Zealand

“…There is therefore a critical need to develop new approaches, techniques, and infrastructure to assess responses of subsurface biospheres to geologic processes, particularly in volcanically and seismically active regions. As of now, they are mainly investigated through their surface manifestations (hot springs), which indicate that subsurface microbial communities are acutely responsive and sensitive to spatial changes in the physicochemical composition of aquifers sourcing the springs (Colman et al, 2021;Fullerton et al, 2021;Power et al, 2023). Collectively, these studies are strong indicators that subsurface litho-autotrophic microbial ecosystems (SliMEs) in hydrothermal systems would similarly be responsive to input of geogenic electron donors or acceptors, regardless of the process involved (e.g.…”

Antarctic geothermal soils exhibit an absence of regional habitat generalist microorganisms

“…For example, Erebus-TR_bin. 23.permissive_ nal (class Nitrososphaeria), present at all four sites, has a limited metabolic repertoire (genes for aerobic CO oxidation, chlorite reduction, nitrite reduction, and sulfur oxidation), with mostly aerobic pathways (Fig. 6C).…”

“…Finally, Antarctic geothermal regions serve as enrichment zones for thermophiles, given the vast amount of ice and snow separating regions and the extremely cold air conditions in Antarctica, resulting in little regional in uence of non-thermophiles on the microbial communities present. Interestingly, past studies of thermophiles, mainly in hot spring environments, have found high niche specialization for temperature or pH, with environmental selection being the primary factor in uencing community assembly and low dispersal rates between sites (20)(21)(22)(23)(24). It is unknown whether the strong winds in Antarctica are capable of overcoming the generally low dispersal rates for thermophiles at Antarctic geothermal regions.…”