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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

Map of the Tuscan Island seep area (A) with the three major sites, close to the islands of Elba and Pianosa, and the islet Scoglio d’Africa. This study focused on the Pomonte seep site (B) and nearby reference sites (Ref1–3). (C) Shows the detailed location of the investigated methane emission spots (ES1a, 1b, 2–4) at the Pomonte seep site. The emission spots are characterized by gas flares (D) as well as black sulfidic sediments that are occasionally covered by white mats of sulfur-oxidizing bacteria (E). The emission spots are situated in 12 m water depth, surrounded by seagrass and rocks and are easily accessible by scuba diving (F).
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Figure 1: Map of the Tuscan Island seep area (A) with the three major sites, close to the islands of Elba and Pianosa, and the islet Scoglio d’Africa. This study focused on the Pomonte seep site (B) and nearby reference sites (Ref1–3). (C) Shows the detailed location of the investigated methane emission spots (ES1a, 1b, 2–4) at the Pomonte seep site. The emission spots are characterized by gas flares (D) as well as black sulfidic sediments that are occasionally covered by white mats of sulfur-oxidizing bacteria (E). The emission spots are situated in 12 m water depth, surrounded by seagrass and rocks and are easily accessible by scuba diving (F).

Mentions: Here, we investigated shallow-water methane seepage off the coast of the Tuscan Island Elba (Italy). Elba is located in the Northern Tyrrhenian Sea, a relatively young (<15 Ma) back-arc basin formed by the roll-back of the Adriatic and Ionian subducting plates. The region is underlain by very thin continental crust and is tectonically very active (Greve et al., 2014 and references therein). Since 1995 the diving team of the HYDRA Field Station on Elba observe gas flares near the coast of the little village Pomonte, the island of Pianosa and the islet Scoglio d’Africa (Figure 1), which are all included in this tectonically active zone. At the Pomonte site the gas bubbles escape from permeable, organic carbon depleted sands and seagrass beds at around 12 m water depth. This unusual combination of tectonic setting, sediment characteristics and hydrodynamics turns the Pomonte seepage site into an outstanding ecosystem that differs from other known seep sites.


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)

Map of the Tuscan Island seep area (A) with the three major sites, close to the islands of Elba and Pianosa, and the islet Scoglio d’Africa. This study focused on the Pomonte seep site (B) and nearby reference sites (Ref1–3). (C) Shows the detailed location of the investigated methane emission spots (ES1a, 1b, 2–4) at the Pomonte seep site. The emission spots are characterized by gas flares (D) as well as black sulfidic sediments that are occasionally covered by white mats of sulfur-oxidizing bacteria (E). The emission spots are situated in 12 m water depth, surrounded by seagrass and rocks and are easily accessible by scuba diving (F).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Map of the Tuscan Island seep area (A) with the three major sites, close to the islands of Elba and Pianosa, and the islet Scoglio d’Africa. This study focused on the Pomonte seep site (B) and nearby reference sites (Ref1–3). (C) Shows the detailed location of the investigated methane emission spots (ES1a, 1b, 2–4) at the Pomonte seep site. The emission spots are characterized by gas flares (D) as well as black sulfidic sediments that are occasionally covered by white mats of sulfur-oxidizing bacteria (E). The emission spots are situated in 12 m water depth, surrounded by seagrass and rocks and are easily accessible by scuba diving (F).
Mentions: Here, we investigated shallow-water methane seepage off the coast of the Tuscan Island Elba (Italy). Elba is located in the Northern Tyrrhenian Sea, a relatively young (<15 Ma) back-arc basin formed by the roll-back of the Adriatic and Ionian subducting plates. The region is underlain by very thin continental crust and is tectonically very active (Greve et al., 2014 and references therein). Since 1995 the diving team of the HYDRA Field Station on Elba observe gas flares near the coast of the little village Pomonte, the island of Pianosa and the islet Scoglio d’Africa (Figure 1), which are all included in this tectonically active zone. At the Pomonte site the gas bubbles escape from permeable, organic carbon depleted sands and seagrass beds at around 12 m water depth. This unusual combination of tectonic setting, sediment characteristics and hydrodynamics turns the Pomonte seepage site into an outstanding ecosystem that differs from other known seep sites.

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