scholarly journals Fauna associated with shallow-water methane seeps in the Laptev Sea

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9018 ◽  
Author(s):  
Andrey A. Vedenin ◽  
Valentin N. Kokarev ◽  
Margarita V. Chikina ◽  
Alexander B. Basin ◽  
Sergey V. Galkin ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Shallow Water ◽  
Control Area ◽  
Laptev Sea ◽  
Methane Seep ◽  
Methane Seeps ◽  
Methane Seepage ◽  
Macrobenthic Community Structure ◽  
Benthic Ecosystems ◽  
Siberian Shelf

Background Methane seeps support unique benthic ecosystems in the deep sea existing due to chemosynthetic organic matter. In contrast, in shallow waters there is little or no effect of methane seeps on macrofauna. In the present study we focused on the recently described methane discharge area at the northern Laptev Sea shelf. The aim of this work was to describe the shallow-water methane seep macrofauna and to understand whether there are differences in macrobenthic community structure between the methane seep and background areas. Methods Samples of macrofauna were taken during three expeditions of RV Akademik Mstislav Keldysh in 2015, 2017 and 2018 using 0.1 m2 grabs and the Sigsbee trawl. 21 grabs and two trawls in total were taken at two methane seep sites named Oden and C15, located at depths of 60–70 m. For control, three 0.1 m2 grabs were taken in area without methane seepage. Results The abundance of macrofauna was higher at methane seep stations compared to non-seep sites. Cluster analysis revealed five station groups corresponding to control area, Oden site and C15 site (the latter represented by three groups). Taxa responsible for differences among the station groups were mostly widespread Arctic species that were more abundant in samples from methane seep sites. However, high densities of symbiotrophic siboglinids Oligobrachia sp. were found exclusively at methane seep stations. In addition, several species possibly new to science were found at several methane seep stations, including the gastropod Frigidalvania sp. and the polychaete Ophryotrocha sp. The fauna at control stations was represented only by well-known and widespread Arctic taxa. Higher habitat heterogeneity of the C15 site compared to Oden was indicated by the higher number of station groups revealed by cluster analysis and higher species richness in C15 trawl sample. The development of the described communities at the shallow-water methane seeps can be related to pronounced oligotrophic environment on the northern Siberian shelf.

scholarly journals Methane Seep Carbonates Host Distinct, Diverse, and Dynamic Microbial Assemblages

mBio ◽  
2015 ◽  
Vol 6 (6) ◽  
Author(s):  
David H. Case ◽  
Alexis L. Pasulka ◽  
Jeffrey J. Marlow ◽  
Benjamin M. Grupe ◽  
Lisa A. Levin ◽  
...  
Keyword(s):  
16S Rrna Gene Sequencing ◽  
Methane Flux ◽  
Rrna Gene ◽  
Methane Seep ◽  
Methane Seeps ◽  
Methane Seepage ◽  
Wide Range ◽  
Sediment Bottom ◽  
Rrna Gene Sequencing ◽  
Geologic Record

ABSTRACTMarine methane seeps are globally distributed geologic features in which reduced fluids, including methane, are advected upward from the subsurface. As a result of alkalinity generation during sulfate-coupled methane oxidation, authigenic carbonates form slabs, nodules, and extensive pavements. These carbonates shape the landscape within methane seeps, persist long after methane flux is diminished, and in some cases are incorporated into the geologic record. In this study, microbial assemblages from 134 native and experimental samples across 5,500 km, representing a range of habitat substrates (carbonate nodules and slabs, sediment, bottom water, and wood) and seepage conditions (active and low activity), were analyzed to address two fundamental questions of seep microbial ecology: (i) whether carbonates host distinct microbial assemblages and (ii) how sensitive microbial assemblages are to habitat substrate type and temporal shifts in methane seepage flux. Through massively parallel 16S rRNA gene sequencing and statistical analysis, native carbonates are shown to be reservoirs of distinct and highly diverse seep microbial assemblages. Unique coupled transplantation and colonization experiments on the seafloor demonstrated that carbonate-associated microbial assemblages are resilient to seep quiescence and reactive to seep activation over 13 months. Various rates of response to simulated seep quiescence and activation are observed among similar phylogenies (e.g.,Chloroflexioperational taxonomic units) and similar metabolisms (e.g., putative S oxidizers), demonstrating the wide range of microbial sensitivity to changes in seepage flux. These results imply that carbonates do not passively record a time-integrated history of seep microorganisms but rather host distinct, diverse, and dynamic microbial assemblages.IMPORTANCESince their discovery in 1984, the global distribution and importance of marine methane seeps have become increasingly clear. Much of our understanding of methane seep microorganisms—from metabolisms to community ecology—has stemmed from detailed studies of seep sediments. However, it has become apparent that carbonates represent a volumetrically significant habitat substrate at methane seeps. Through combinedin situcharacterization and incubation experiments, this study demonstrates that carbonates host microbial assemblages distinct from and more diverse than those of other seep habitats. This emphasizes the importance of seep carbonates as biodiversity locales. Furthermore, we demonstrate that carbonate-associated microbial assemblages are well adapted to withstand fluctuations in methane seepage, and we gain novel insight into particular taxa that are responsive (or recalcitrant) to changes in seep conditions.

scholarly journals Proposed Methodology to Quantify the Amount of Methane Seepage by Understanding the Correlation Between Methane Plumes and Originating Seeps

2021 ◽  
Vol 9 ◽  
Author(s):  
Chiharu Aoyama ◽  
Nidomu Maeda
Keyword(s):  
Environmental Impact ◽  
Target Position ◽  
Energy Resources ◽  
Basic Data ◽  
Methane Seeps ◽  
Remotely Operated Vehicle ◽  
Methane Seepage ◽  
The World ◽  
Backscattering Strength ◽  
The Mean

In recent years, discoveries of methane plumes (also called methane flares) have been reported in various sea areas around the world. Clusters of naturally seeping methane bubbles rising from the seafloor are visualized as methane plumes on the echograms of quantitative echo sounders and multibeam sonars. In order to determine if seeping methane can be used as energy resources and its environmental impact, it is necessary to estimate the amount of naturally seeping methane. From April, 2020, a 3-year project is being conducted in Japan to evaluate the amount of methane seepage from methane plumes. The authors propose the following steps to quantify the amount of methane seepage accurately. First of all, methane plumes in the Exclusive Economic Zone (EEZ) of Japan are mapped out using acoustic devices such as quantitative echo sounders and multibeam sonars. Secondly, methane bubbles of a few millimeters in diameter from methane seeps at seafloor are collected and sampled using a cone-shaped collector with 20 cm in diameter, operated by Remotely Operated Vehicle (ROV). If we can identify the number of seep mouths that form into one single plume, we will be able to quantify the methane seepage from one plume. Based on this result, calibration of the mean backscattering strength and the amount of seeping methane from methane plumes becomes possible and will be applied to the mapped plumes in order to estimate the methane seepage in the EEZ of Japan. Once this calibration is established, it can be applied to the methane plumes observed worldwide, and methane seepage can be quantified simply by acoustic observations of methane plumes. In this study, a method to verify the correlation between methane plumes and methane seeps is introduced, as well as a method to locate methane seeps effectively using the Target Position function of a quantitative echo sounder. The authors intend to use this as the basic data for establishing a method to estimate the amount of methane released from a methane plume by observing the methane plume acoustically.

Methane seeps on the outer shelf of the Laptev Sea: characteristic features, structural control, and benthic fauna

2020 ◽  
Vol 40 (4) ◽  
pp. 541-557 ◽  
Author(s):  
B. Baranov ◽  
S. Galkin ◽  
A. Vedenin ◽  
K. Dozorova ◽  
A. Gebruk ◽  
...  
Keyword(s):  
Structural Control ◽  
Benthic Fauna ◽  
Outer Shelf ◽  
Laptev Sea ◽  
Methane Seeps ◽  
Characteristic Features ◽  
The Laptev Sea

The Fault System Controlling Methane Seeps on the Shelf of the Laptev Sea

2019 ◽  
Vol 486 (1) ◽  
pp. 571-574 ◽  
Author(s):  
B. V. Baranov ◽  
L. I. Lobkovsky ◽  
K. A. Dozorova ◽  
N. V. Tsukanov
Keyword(s):  
Fault System ◽  
Laptev Sea ◽  
Methane Seeps ◽  
The Laptev Sea

Authigenic Mg-calcite at a cold methane seep site in the Laptev Sea

Oceanology ◽  
2017 ◽  
Vol 57 (1) ◽  
pp. 174-191 ◽  
Author(s):  
M. D. Kravchishina ◽  
A. Yu. Lein ◽  
A. S. Savvichev ◽  
L. E. Reykhard ◽  
O. M. Dara ◽  
...  
Keyword(s):  
Laptev Sea ◽  
Methane Seep ◽  
The Laptev Sea ◽  
Seep Site
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