scholarly journals Distinct methane-dependent biogeochemical states in Arctic seafloor gas hydrate mounds

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Scott A. Klasek ◽  
Wei-Li Hong ◽  
Marta E. Torres ◽  
Stella Ross ◽  
Katelyn Hostetler ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Gas Hydrate ◽  
High Arctic ◽  
Community Diversity ◽  
Sulfate Reducing ◽  
Gas Seepage ◽  
Microbial Responses ◽  
Methane Fluxes ◽  
Anaerobic Methanotrophs ◽  
Natural Settings

AbstractArchaea mediating anaerobic methane oxidation are key in preventing methane produced in marine sediments from reaching the hydrosphere; however, a complete understanding of how microbial communities in natural settings respond to changes in the flux of methane remains largely uncharacterized. We investigate microbial communities in gas hydrate-bearing seafloor mounds at Storfjordrenna, offshore Svalbard in the high Arctic, where we identify distinct methane concentration profiles that include steady-state, recently-increasing subsurface diffusive flux, and active gas seepage. Populations of anaerobic methanotrophs and sulfate-reducing bacteria were highest at the seep site, while decreased community diversity was associated with a recent increase in methane influx. Despite high methane fluxes and methanotroph doubling times estimated at 5–9 months, microbial community responses were largely synchronous with the advancement of methane into shallower sediment horizons. Together, these provide a framework for interpreting subseafloor microbial responses to methane escape in a warming Arctic Ocean.

scholarly journals Distinct methane-driven biogeochemical regimes in Arctic seafloor gas hydrate mounds

2020 ◽  
Author(s):  
Scott Klasek ◽  
Wei-Li Hong ◽  
Marta Torres ◽  
Stella Ross ◽  
Katelyn Hostetler ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Gas Hydrate ◽  
Methane Flux ◽  
High Arctic ◽  
Community Diversity ◽  
Sulfate Reducing ◽  
Recent Increase ◽  
Gas Seepage ◽  
Microbial Responses ◽  
Methane Fluxes

Abstract Archaea mediating anaerobic methane oxidation are key in preventing methane produced in marine sediments from reaching the hydrosphere; however, a complete understanding of how microbial communities in natural settings respond to changes in methane flux remains largely uncharacterized. We investigate microbial communities in gas hydrate-bearing seafloor mounds at Storfjordrenna, offshore Svalbard in the high Arctic, where distinct methane flux regimes ranging from steady-state dynamics, recent increase in subsurface diffusive flux, and gas seepage were identified. Populations of anaerobic methanotrophs and sulfate-reducing bacteria were highest at the seep site, while a recent increase in methane influx was associated with decreased community diversity. Despite high methane fluxes and methanotroph doubling times estimated at 5-9 months, microbial community responses were largely synchronous with the advancement of methane into shallower sediment horizons. Together, these provide a framework for interpreting subseafloor microbial responses to methane escape in a changing Arctic.

scholarly journals An experimental study on short-term changes in the anaerobic oxidation of methane in response to varying methane and sulfate fluxes

2009 ◽  
Vol 6 (5) ◽  
pp. 867-876 ◽  
Author(s):  
G. Wegener ◽  
A. Boetius
Keyword(s):  
Cold Seep ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
Anaerobic Oxidation ◽  
Short Term ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Column System ◽  
Methane Fluxes ◽  
Anaerobic Methanotrophs

Abstract. A major role in regulation of global methane fluxes has been attributed to the process of anaerobic oxidation of methane (AOM), which is performed by consortia of methanotrophic archaea and sulfate reducing bacteria. An important question remains how these energy limited, slow growing microorganisms with generation times of 3–7 months respond to rapid natural variations in methane fluxes at cold seeps. We used an experimental flow-through column system filled with cold seep sediments naturally enriched in methanotrophic communities, to test their responses to short-term variations in methane and sulfate fluxes. At stable methane and sulfate concentrations of ~2 mM and 28 mM, respectively, we measured constant rates of AOM and sulfate reduction (SR) for up to 160 days of incubation. When percolated with methane-free medium, the anaerobic methanotrophs ceased to produce sulfide. After a starvation phase of 40 days, the addition of methane restored former AOM and SR rates immediately. At methane concentrations between 0–2.3 mM we measured a linear correlation between methane availability, AOM and SR. At constant fluid flow velocities of 30 m yr−1, ca. 50% of the methane was consumed by the anaerobic methanotrophic (ANME) population at all concentrations tested. Reducing the sulfate concentration from 28 to 1 mM, a decrease in AOM and SR by 50% was observed, and 45% of the methane was consumed. Hence, the marine anaerobic methanotrophs (ANME) are capable of oxidizing substantial amounts of methane over a wide and variable range of fluxes of the reaction educts.

MICROBIAL COMMUNITIES AND DIFFERENTIAL METHANE FLUX IN ARCTIC GAS HYDRATE MOUNDS

2017 ◽  
Author(s):  
Stella C. Ross ◽  
◽  
Scott Klasek ◽  
Wei-Li Hong ◽  
Marta E. Torres ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Gas Hydrate ◽  
Methane Flux

scholarly journals Early Spring Snowmelt and Summer Droughts Strongly Impair the Resilience of Key Microbial Communities in Subalpine Grassland Ecosystems

2021 ◽  
Author(s):  
Farhan Hafeez ◽  
Lionel Bernard ◽  
Jean-Christophe Clement ◽  
Franck Poly ◽  
Thomas Pommier
Keyword(s):  
Microbial Communities ◽  
Plant Biomass ◽  
Early Spring ◽  
Climatic Extremes ◽  
Soil Microbial ◽  
Cascading Effect ◽  
Growing Seasons ◽  
Grassland Ecosystems ◽  
Microbial Responses ◽  
Early Snowmelt

Subalpine grassland ecosystems are important from biodiversity, agriculture, and touristic perspectives but their resilience to seasonally occurring climatic extremes is increasingly challenged with climate change, accelerating their vulnerability to tipping points. Microbial communities, which are central in ecosystem functioning, are usually considered as more resistant and highly resilient to such extreme events due to their functional redundancy and strong selection in residing habitats. To investigate this, we explored the soil microbial responses upon recurrent summer droughts associated with early snowmelt in grasslands mesocosms set-up at the Lautaret Pass (French Alps). Potential respiration, nitrification and denitrification were monitored over a period of two growing seasons along with quantification of community gene abundances of total bacteria as well as (de)nitrifiers. Results revealed that droughts had a low and short-term impact on bacterial total respiration supporting their hypothesized high resistance and ability to recover. Nitrification and abundances of the corresponding functional guilds showed relatively strong resistance to summer droughts but declined in response to early snowmelt. This triggered a cascading effect on denitrification but also on the abundances of denitrifying communities which could recover from all climatic extremes except from the summer droughts where nitrifiers were collapsed. Denitrification and the respective functional groups faced high impact of applied stresses with strong reduction in the abundance and activity of this specialized community. Although, the consequently lower microbial competition for nitrate may be positive for plant biomass production, warnings exist when considering the potential nitrogen leaching from these ecosystems as well as risks of greenhouses gases emission such as N2O

scholarly journals ANME-1 archaea drive methane accumulation and removal in estuarine sediments

2020 ◽  
Author(s):  
Richard Kevorkian ◽  
Sean Callahan ◽  
Rachel Winstead ◽  
Karen G. Lloyd
Keyword(s):  
16S Rrna ◽  
Sulfate Reducing Bacteria ◽  
Low Energy ◽  
Estuarine Sediments ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Sulfate Reducing ◽  
Hydrogenotrophic Methanogenesis ◽  
Natural Settings ◽  
Reducing Bacteria

AbstractUncultured members of the Methanomicrobia called ANME-1 perform the anaerobic oxidation of methane (AOM) through a process that uses much of the methanogenic pathway. It is unknown whether ANME-1 obligately perform AOM, or whether some of them can perform methanogenesis when methanogenesis is exergonic. Most marine sediments lack advective transport of methane, so AOM occurs in the sulfate methane transition zone (SMTZ) where sulfate-reducing bacteria consume hydrogen produced by fermenters, making hydrogenotrophic methanogenesis exergonic in the reverse direction. When sulfate is depleted deeper in the sediments, hydrogen accumulates making hydrogenotrophic methanogenesis exergonic, and methane accumulates in the methane zone (MZ). In White Oak River estuarine sediments, we found that ANME-1 comprised 99.5% of 16S rRNA genes from amplicons and 100% of 16S rRNA genes from metagenomes of the Methanomicrobia in the SMTZ and 99.9% and 98.3%, respectively, in the MZ. Each of the 16 ANME-1 OTUs (97% similarity) had peaks in the SMTZ that coincided with peaks of putative sulfate-reducing bacteria Desulfatiglans sp. and SEEP-SRB1. In the MZ, ANME-1, but no putative sulfate-reducing bacteria or cultured methanogens, increased with depth. Using publicly available data, we found that ANME-1 was the only group expressing methanogenic genes during both net AOM and net methanogenesis in an enrichment. The commonly-held belief that ANME-1 perform AOM is based on the fact that they dominate natural settings and enrichments where net AOM is measured. We found that ANME-1 also dominate natural settings and enrichment where net methanogenesis is measured, so we conclude that ANME-1 perform methane production. Alternating between AOM and methanogenesis, either in a single ANME-1 cell or between different subclades with similar 16S rRNA sequences of ANME-1, may confer a competitive advantage, explaining the predominance of low-energy adapted ANME-1 in methanogenic sediments worldwide.Abstract ImportanceLife may operate differently at very low energy levels. Natural populations of microbes that make methane survive on some of the lowest energy yields of all life. From all available data, we infer that these microbes alternate between methane production and oxidation, depending on which process is energy-yielding in the environment. This means that much of the methane produced naturally in marine sediments occurs through an organism that is also capable of destroying it under different circumstances.

scholarly journals Comparing Rock-inhabiting Microbial Communities in Different Rock Types from a High Arctic Polar Desert

2018 ◽  
Author(s):  
Yong-Hoe Choe ◽  
Mincheol Kim ◽  
Jusun Woo ◽  
Mi Jung Lee ◽  
Jong Ik Lee ◽  
...  
Keyword(s):  
Microbial Communities ◽  
High Arctic ◽  
Polar Desert ◽  
Rock Types

Seasonal variability of natural methane seepage offshore Western Svalbard

2021 ◽  
Author(s):  
Manuel Moser ◽  
Knut Ola Dølven ◽  
Bénédicte Ferré
Keyword(s):  
Gas Hydrate ◽  
Bottom Water ◽  
Methane Flux ◽  
Mixing Rate ◽  
Bottom Water Temperature ◽  
Acoustic Data ◽  
Methane Seepage ◽  
Continental Shelves ◽  
Water Conditions ◽  
Methane Fluxes

<p>Natural methane seepage from the seafloor to the water column occurs worldwide in marine environments, from continental shelves to deep-sea basins. Depending on water depth, methane fluxes, and mixing rate of the seawater, methane may partially reach the atmosphere, where it could contribute to the global greenhouse effect. Estimates of annual marine methane fluxes are commonly calculated from hydro-acoustic data collected during single research surveys. These snapshot estimates neglect short (i.e., tide) and long (seasonal) variations.</p><p>Here we compare the seepage activity along the upper limit of the gas hydrate stability zone offshore Western Svalbard in August 2017 (bottom water temperature (BT) ~3.46°C), June 2020 (BT ~1.75°C), and November 2020 (BT ~3.96°C) using high-resolution vessel-based multibeam data. Our results complete annual methane flux estimates by Ferré et al. (2020) and confirm a significantly reduced seepage activity during the cold bottom-water conditions. We investigate short-term variation by comparing a 7.5 km long multibeam section at three phases of the lunar semidiurnal (M2) tide. We will discuss how these processes affect annual methane fluxes estimates offshore Svalbard and further Arctic methane fluxes estimates.</p><p>The research is part of the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) and is supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259 and UiT.</p><p> </p><p>Ferré, B., Jansson, P. G., Moser, M., Serov, P., Portnov, A., Graves, C. A., et al. (2020). Reduced methane seepage from Arctic sediments during cold bottom-water conditions. Nat. Geosci. 13, 144–148. DOI: 10.1038/s41561-019-0515-3</p>

scholarly journals Resilience and Assemblage of Soil Microbiome in Response to Chemical Contamination Combined with Plant Growth

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Shuo Jiao ◽  
Weimin Chen ◽  
Gehong Wei
Keyword(s):  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Soil Microbiome ◽  
Chemical Contamination ◽  
Plant Interactions ◽  
Soil Microbial Diversity ◽  
Soil Microbial ◽  
Microbial Responses ◽  
Legume Plants ◽  
Functional Profiles

ABSTRACT A lack of knowledge of the microbial responses to environmental change at the species and functional levels hinders our ability to understand the intrinsic mechanisms underlying the maintenance of microbial ecosystems. Here, we present results from temporal microcosms that introduced inorganic and organic contaminants into agro-soils for 90 days, with three common legume plants. Temporal dynamics and assemblage of soil microbial communities and functions in response to contamination under the influence of growth of different plants were explored via sequencing of the 16S rRNA amplicon and by shotgun metagenomics. Soil microbial alpha diversity and structure at the taxonomic and functional levels exhibited resilience patterns. Functional profiles showed greater resilience than did taxonomic ones. Different legume plants imposed stronger selection on taxonomic profiles than on functional ones. Network and random forest analyses revealed that the functional potential of soil microbial communities was fostered by various taxonomic groups. Betaproteobacteria were important predictors of key functional traits such as amino acid metabolism, nucleic acid metabolism, and hydrocarbon degradation. Our study reveals the strong resilience of the soil microbiome to chemical contamination and sensitive responses of taxonomic rather than functional profiles to selection processes induced by different legume plants. This is pivotal to develop approaches and policies for the protection of soil microbial diversity and functions in agro-ecosystems with different response strategies from global environmental drivers, such as soil contamination and plant invasion. IMPORTANCE Exploring the microbial responses to environmental disturbances is a central issue in microbial ecology. Understanding the dynamic responses of soil microbial communities to chemical contamination and the microbe-soil-plant interactions is essential for forecasting the long-term changes in soil ecosystems. Nevertheless, few studies have applied multi-omics approaches to assess the microbial responses to soil contamination and the microbe-soil-plant interactions at the taxonomic and functional levels simultaneously. Our study reveals clear succession and resilience patterns of soil microbial diversity and structure in response to chemical contamination. Different legume plants exerted stronger selection processes on taxonomic than on functional profiles in contaminated soils, which could benefit plant growth and fitness as well as foster the potential abilities of hydrocarbon degradation and metal tolerance. These results provide new insight into the resilience and assemblage of soil microbiome in response to environmental disturbances in agro-ecosystems at the species and functional levels.

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