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Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy.

Ruff SE, Kuhfuss H, Wegener G, Lott C, Ramette A, Wiedling J, Knittel K, Weber M - Front Microbiol (2016)

Bottom Line: Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM.With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands.To link AOM phylotypes with seep habitats and to enable future meta-analyses we thus propose that seep environment ontology needs to be further specified.

View Article: PubMed Central - PubMed

Affiliation: Department for Molecular Ecology, Max Planck Institute for Marine MicrobiologyBremen, Germany; HGF MPG Group for Deep Sea Ecology and Technology, Max Planck Institute for Marine MicrobiologyBremen, Germany.

ABSTRACT
The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct microbial habitats due to their unique biogeochemical and physical characteristics. To link AOM phylotypes with seep habitats and to enable future meta-analyses we thus propose that seep environment ontology needs to be further specified.

No MeSH data available.


Related in: MedlinePlus

Concentration profiles of methane, dissolved inorganic carbon (DIC), DIC isotopic signature (vs. VPDB), alkalinity, sulfate, and sulfide of the three investigated emission spots: ES1a, ES2, and ES3, as well as a reference spot (Ref). Gray circles show water column measurements from 50 cm above seafloor.
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Figure 2: Concentration profiles of methane, dissolved inorganic carbon (DIC), DIC isotopic signature (vs. VPDB), alkalinity, sulfate, and sulfide of the three investigated emission spots: ES1a, ES2, and ES3, as well as a reference spot (Ref). Gray circles show water column measurements from 50 cm above seafloor.

Mentions: The emitted gas contained up to 85% methane (and not further quantified proportions of ethane, propane, and CO2), with an unusual carbon isotopic signature of around ∂13C = -16aaaa vs. the Vienna Pee Dee Belemnite (VPDB) standard. This indicated abiogenic origin, which was further supported by the basement of this site consisting of fractured magmatic rock and the low organic carbon content of the sediment. We measured methane concentrations between 50 and 550 μM in the pore water (Figure 2), whereas in the reference sediments methane was below the detection limit (<1 μM; Figure 2). We assume, that locally the methane concentrations were rather underestimated, due to outgassing and constant dilution occurring in advective systems.


Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy.

Ruff SE, Kuhfuss H, Wegener G, Lott C, Ramette A, Wiedling J, Knittel K, Weber M - Front Microbiol (2016)

Concentration profiles of methane, dissolved inorganic carbon (DIC), DIC isotopic signature (vs. VPDB), alkalinity, sulfate, and sulfide of the three investigated emission spots: ES1a, ES2, and ES3, as well as a reference spot (Ref). Gray circles show water column measurements from 50 cm above seafloor.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814501&req=5

Figure 2: Concentration profiles of methane, dissolved inorganic carbon (DIC), DIC isotopic signature (vs. VPDB), alkalinity, sulfate, and sulfide of the three investigated emission spots: ES1a, ES2, and ES3, as well as a reference spot (Ref). Gray circles show water column measurements from 50 cm above seafloor.
Mentions: The emitted gas contained up to 85% methane (and not further quantified proportions of ethane, propane, and CO2), with an unusual carbon isotopic signature of around ∂13C = -16aaaa vs. the Vienna Pee Dee Belemnite (VPDB) standard. This indicated abiogenic origin, which was further supported by the basement of this site consisting of fractured magmatic rock and the low organic carbon content of the sediment. We measured methane concentrations between 50 and 550 μM in the pore water (Figure 2), whereas in the reference sediments methane was below the detection limit (<1 μM; Figure 2). We assume, that locally the methane concentrations were rather underestimated, due to outgassing and constant dilution occurring in advective systems.

Bottom Line: Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM.With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands.To link AOM phylotypes with seep habitats and to enable future meta-analyses we thus propose that seep environment ontology needs to be further specified.

View Article: PubMed Central - PubMed

Affiliation: Department for Molecular Ecology, Max Planck Institute for Marine MicrobiologyBremen, Germany; HGF MPG Group for Deep Sea Ecology and Technology, Max Planck Institute for Marine MicrobiologyBremen, Germany.

ABSTRACT
The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct microbial habitats due to their unique biogeochemical and physical characteristics. To link AOM phylotypes with seep habitats and to enable future meta-analyses we thus propose that seep environment ontology needs to be further specified.

No MeSH data available.


Related in: MedlinePlus