Science.gov

Sample records for cold seep sediments

  1. Anaerobic oxidation of methane in hypersaline cold seep sediments.

    PubMed

    Maignien, Loïs; Parkes, R John; Cragg, Barry; Niemann, Helge; Knittel, Katrin; Coulon, Stephanie; Akhmetzhanov, Andrey; Boon, Nico

    2013-01-01

    Life in hypersaline environments is typically limited by bioenergetic constraints. Microbial activity at the thermodynamic edge, such as the anaerobic oxidation of methane (AOM) coupled to sulphate reduction (SR), is thus unlikely to thrive in these environments. In this study, carbon and sulphur cycling was investigated in the extremely hypersaline cold seep sediments of Mercator mud volcano. AOM activity was partially inhibited but still present at salinity levels of 292 g L(-1) (c. eightfold sea water concentration) with rates of 2.3 nmol cm(-3) day(-1) and was even detectable under saturated conditions. Methane and evaporite-derived sulphate comigrated in the ascending geofluids, which, in combination with a partial activity inhibition, resulted in AOM activity being spread over unusually wide depth intervals. Up to 79% of total cells in the AOM zone were identified by fluorescence in situ hybridization (FISH) as anaerobic methanotrophs of the ANME-1. Most ANME-1 cells formed monospecific chains without any attached partner. At all sites, AOM activity co-occurred with SR activity and sometimes significantly exceeded it. Possible causes of these unexpected results are discussed. This study demonstrates that in spite of a very low energy yield of AOM, microorganisms carrying this reaction can thrive in salinity up to halite saturation.

  2. High rates of denitrification and nitrate removal in cold seep sediments

    PubMed Central

    Bowles, Marshall; Joye, Samantha

    2011-01-01

    We measured denitrification and nitrate removal rates in cold seep sediments from the Gulf of Mexico. Heterotrophic potential denitrification rates were assayed in time-series incubations. Surficial sediments inhabited by Beggiatoa exhibited higher heterotrophic potential denitrification rates (32 μ N reduced day−1) than did deeper sediments (11 μ N reduced day−1). Nitrate removal rates were high in both sediment horizons. These nitrate removal rates translate into rapid turnover times (<1 day) for the nitrate pool, resulting in a faster turnover for the nitrate pool than for the sulfate pool. Together, these data underscore the rigorous nature of internal nitrogen cycling at cold seeps and the requirement for novel mechanisms to provide nitrate to the sediment microbial community. PMID:20944683

  3. High rates of denitrification and nitrate removal in cold seep sediments.

    PubMed

    Bowles, Marshall; Joye, Samantha

    2011-03-01

    We measured denitrification and nitrate removal rates in cold seep sediments from the Gulf of Mexico. Heterotrophic potential denitrification rates were assayed in time-series incubations. Surficial sediments inhabited by Beggiatoa exhibited higher heterotrophic potential denitrification rates (32 μM N reduced day(-1)) than did deeper sediments (11 μM N reduced day(-1)). Nitrate removal rates were high in both sediment horizons. These nitrate removal rates translate into rapid turnover times (<1 day) for the nitrate pool, resulting in a faster turnover for the nitrate pool than for the sulfate pool. Together, these data underscore the rigorous nature of internal nitrogen cycling at cold seeps and the requirement for novel mechanisms to provide nitrate to the sediment microbial community.

  4. Evidence of active methanogen communities in shallow sediments of the sonora margin cold seeps.

    PubMed

    Vigneron, Adrien; L'Haridon, Stéphane; Godfroy, Anne; Roussel, Erwan G; Cragg, Barry A; Parkes, R John; Toffin, Laurent

    2015-05-15

    In the Sonora Margin cold seep ecosystems (Gulf of California), sediments underlying microbial mats harbor high biogenic methane concentrations, fueling various microbial communities, such as abundant lineages of anaerobic methanotrophs (ANME). However, the biodiversity, distribution, and metabolism of the microorganisms producing this methane remain poorly understood. In this study, measurements of methanogenesis using radiolabeled dimethylamine, bicarbonate, and acetate showed that biogenic methane production in these sediments was mainly dominated by methylotrophic methanogenesis, while the proportion of autotrophic methanogenesis increased with depth. Congruently, methane production and methanogenic Archaea were detected in culture enrichments amended with trimethylamine and bicarbonate. Analyses of denaturing gradient gel electrophoresis (DGGE) fingerprinting and reverse-transcribed PCR-amplified 16S rRNA sequences retrieved from these enrichments revealed the presence of active methylotrophic Methanococcoides burtonii relatives and several new autotrophic Methanogenium lineages, confirming the cooccurrence of Methanosarcinales and Methanomicrobiales methanogens with abundant ANME populations in the sediments of the Sonora Margin cold seeps.

  5. Evidence of Active Methanogen Communities in Shallow Sediments of the Sonora Margin Cold Seeps

    PubMed Central

    L'Haridon, Stéphane; Godfroy, Anne; Roussel, Erwan G.; Cragg, Barry A.; Parkes, R. John; Toffin, Laurent

    2015-01-01

    In the Sonora Margin cold seep ecosystems (Gulf of California), sediments underlying microbial mats harbor high biogenic methane concentrations, fueling various microbial communities, such as abundant lineages of anaerobic methanotrophs (ANME). However, the biodiversity, distribution, and metabolism of the microorganisms producing this methane remain poorly understood. In this study, measurements of methanogenesis using radiolabeled dimethylamine, bicarbonate, and acetate showed that biogenic methane production in these sediments was mainly dominated by methylotrophic methanogenesis, while the proportion of autotrophic methanogenesis increased with depth. Congruently, methane production and methanogenic Archaea were detected in culture enrichments amended with trimethylamine and bicarbonate. Analyses of denaturing gradient gel electrophoresis (DGGE) fingerprinting and reverse-transcribed PCR-amplified 16S rRNA sequences retrieved from these enrichments revealed the presence of active methylotrophic Methanococcoides burtonii relatives and several new autotrophic Methanogenium lineages, confirming the cooccurrence of Methanosarcinales and Methanomicrobiales methanogens with abundant ANME populations in the sediments of the Sonora Margin cold seeps. PMID:25769831

  6. Comparison of the microbial diversity in cold-seep sediments from different depths in the Nankai Trough.

    PubMed

    Arakawa, Shizuka; Sato, Takako; Yoshida, Yasuhiko; Usami, Ron; Kato, Chiaki

    2006-02-01

    We have investigated the molecular phylogeny of cold-seep sediments obtained from the Nankai Trough, at depths of about 600, 2,000, and 3,300 m, and compared the microbial diversity profiles of those sediments samples. The gamma-Proteobacteria that might function as sulfide oxidizers and the symbiotically related delta-Proteobacteria which might function as sulfate reducers were identified amongst the bacteria from all depths of the sediments. However, anoxic methane oxidizing archaea (ANME) and methanogens were only found in the 600 m deep sediments. These results indicated that the cold-seep microbial sulfur circulation system could be functioning in the shallow seep sediment at a depth of 600 m and the microbial activities at these sites might be more dynamic than at other deeper cold-seep sites.

  7. Active archaeal communities at cold seep sediments populated by Siboglinidae tubeworms from the Storegga Slide.

    PubMed

    Lazar, Cassandre Sara; Dinasquet, Julie; Pignet, Patricia; Prieur, Daniel; Toffin, Laurent

    2010-10-01

    Siboglinid tubeworms in cold seep sediments can locally modify the geochemical gradients of electron acceptors and donors, hence creating potential microhabitats for prokaryotic populations. The archaeal communities associated with sediments populated by Oligobrachia haakonmosbiensis and Sclerolinum contortum Siboglinid tubeworms in the Storegga Slide were examined in this study. Vertical distribution of archaeal communities was investigated using denaturing gradient gel electrophoresis based on 16S rRNA genes. The active fraction of the archaeal community was assessed by using reverse-transcribed rRNA. Archaeal communities associated with sediments colonized by tubeworms were affiliated with uncultivated archaeal lineages of the Crenarchaeota and Euryarchaeota. The composition of the active archaeal populations changed with depth indicating a reorganization of microbial communities. 16S rRNA gene libraries were dominated by sequences affiliated to the Rice Cluster V which are unusual in marine sediment samples. Moreover, this study provides the first evidence of living Crenarchaeota of the Rice Cluster V in cold seep sediments. Furthermore, the Storegga Slide sediments harbored a high diversity of other minor groups of uncultivated lineages including Terrestrial Miscellaneous Euryarchaeotal Group, Marine Benthic Group (MBG)-D, MBG-E, Deep-Sea Hydrothermal Vent Euryarchaeotal Group, Lake Dagow Sediment, Val Kotinen Lake clade III, and Sippenauer Moor 1. Thus, we hypothesize that the vertical geochemical imprint created by the tubeworms could support broad active archaeal populations in the Siboglinidae-populated Storegga Slide sediments.

  8. Short-chain alkane cycling in deep Gulf of Mexico cold-seep sediments

    NASA Astrophysics Data System (ADS)

    Sibert, R.; Joye, S. B.; Hunter, K.

    2015-12-01

    Mixtures of light hydrocarbon gases are common in deep Gulf of Mexico cold-seep sediments, and are typically dissolved in pore fluids, adsorbed to sediment particles, trapped in methane ice, or as free gas. The dominant component in these natural gas mixtures is usually methane (>80% C1), but ethane (C2) and propane (C3) are nearly always present in trace amounts (<1% total). The processes that control the concentration and isotopic signature of these gases in sediments are well explained for methane, but the controls for C2/C3 cycling are still a relative mystery. Methane production proceeds in deep anoxic sediments by either 1) thermocatalytic cracking of fossil organic matter, or 2) as a direct product of microbial metabolism, i.e. methanogenesis. In surface sediments, it appears that both microbial consumption and chemical deposition of methane (i.e. as methane clathrate) ensures that >95% of the methane produced at depth never reaches the water column. Production of C1 and C2 in deep-sea sediments has been historically attributed only to thermocatalytic processes, though limited data suggests production of C2/C3 compounds through the activity of archaea at depth. Furthermore, carbon isotopic data on ethane and propane from deep cores of Gulf of Mexico sediments suggest alkanogenesis at >3 m depth in the sediment column and alkane oxidation in uppermost oxidant-rich sediments. Additional studies have also isolated microorganisms capable of oxidizing ethane and propane in the laboratory, but field studies of microbial-driven dynamics of C2/C3 gases in cold-seep sediments are rare. Here, we present the results of a series of incubation experiments using sediment slurries culled from surface sediments from one of the most prolific natural oil and gas seeps in the Gulf of Mexico. Rates of alkane oxidation were measured under a variety of conditions to assess the surface-driven microbial controls on C2/C3 cycling in cold-seep environments. Such microbial processes

  9. Enumeration of viruses and prokaryotes in deep-sea sediments and cold seeps of the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Kellogg, Christina A.

    2010-11-01

    Little is known about the distribution and abundance of viruses in deep-sea cold-seep environments. Like hydrothermal vents, seeps support communities of macrofauna that are sustained by chemosynthetic bacteria. Sediments close to these communities are hypothesized to be more microbiologically active and therefore to host higher numbers of viruses than non-seep areas. Push cores were taken at five types of Gulf of Mexico habitats at water depths below 1000 m using a remotely operated vehicle (ROV). The habitats included non-seep reference sediment, brine seeps, a microbial mat, an urchin field, and a pogonophoran worm community. Samples were processed immediately for enumeration of viruses and prokaryotes without the addition of a preservative. Prokaryote counts were an order of magnitude lower in sediments directly in contact with macrofauna (urchins, pogonophorans) compared to all other samples (107 vs. 108 cells g-1 dry weight) and were highest in areas of elevated salinity (brine seeps). Viral-Like Particle (VLP) counts were lowest in the reference sediments and pogonophoran cores (108 VLP g-1 dry wt), higher in brine seeps (109 VLP g-1 dry wt), and highest in the microbial mats (1010 VLP g-1 dry wt). Virus-prokaryote ratios (VPR) ranged from <5 in the reference sediment to >30 in the microbial mats and >60 in the urchin field. VLP counts and VPR were all significantly greater than those reported from sediments in the deep Mediterranean Sea and in most cases were higher than recent data from a cold-seep site near Japan. The high VPR suggest that greater microbial activity in or near cold-seep environments results in greater viral production and therefore higher numbers of viruses.

  10. Enumeration of viruses and prokaryotes in deep-sea sediments and cold seeps of the Gulf of Mexico

    USGS Publications Warehouse

    Kellogg, Christina A.

    2010-01-01

    Little is known about the distribution and abundance of viruses in deep-sea cold-seep environments. Like hydrothermal vents, seeps support communities of macrofauna that are sustained by chemosynthetic bacteria. Sediments close to these communities are hypothesized to be more microbiologically active and therefore to host higher numbers of viruses than non-seep areas. Push cores were taken at five types of Gulf of Mexico habitats at water depths below 1000 m using a remotely operated vehicle (ROV). The habitats included non-seep reference sediment, brine seeps, a microbial mat, an urchin field, and a pogonophoran worm community. Samples were processed immediately for enumeration of viruses and prokaryotes without the addition of a preservative. Prokaryote counts were an order of magnitude lower in sediments directly in contact with macrofauna (urchins, pogonophorans) compared to all other samples (107 vs. 108 cells g-1 dry weight) and were highest in areas of elevated salinity (brine seeps). Viral-Like Particle (VLP) counts were lowest in the reference sediments and pogonophoran cores (108 VLP g-1 dry wt), higher in brine seeps (109 VLP g-1 dry wt), and highest in the microbial mats (1010 VLP g-1 dry wt). Virus-prokaryote ratios (VPR) ranged from <5 in the reference sediment to >30 in the microbial mats and >60 in the urchin field. VLP counts and VPR were all significantly greater than those reported from sediments in the deep Mediterranean Sea and in most cases were higher than recent data from a cold-seep site near Japan. The high VPR suggest that greater microbial activity in or near cold-seep environments results in greater viral production and therefore higher numbers of viruses.

  11. Microbial Diversity in Sediments Collected from the Deepest Cold-Seep Area, the Japan Trench.

    PubMed

    Li; Kato; Horikoshi

    1999-07-01

    : The Japan Trench land slope at a depth of 6,400 m is the deepest cold-seep environment with Calyptogena communities. Sediment samples from inside and beside the Calyptogena communities were collected, and the microbial diversity in the sediment samples was studied by molecular phylogenetic techniques. From DNA extracted directly from the sediment samples, 16S rDNAs were amplified by the polymerase chain reaction method. The sequences of the amplified 16S rDNAs selected by restriction fragment length polymorphism analysis were determined and compared with sequences in DNA databases. The results showed that 33 different bacterial 16S rDNA sequences from the two samples analyzed fell into similar phylogenetic categories, the alpha-, gamma-, delta-, and varepsilon-subdivisions of Proteobacteria, Cytophaga, and gram-positive bacteria; some of the 16S rDNA sequences were common to both samples. delta- and varepsilon-Proteobacteria-related sequences were abundant in both sediments. These sequences are mostly related to sulfate-reducing or sulfur-reducing bacteria and epibionts, respectively. Eight different archaeal 16S rDNA sequences were cloned from the sediments. The majority of the archaeal 16S rDNA sequences clustered in Crenarchaeota and showed high similarities to marine group I archaeal rDNA. A Methanococcoides burtonii-related sequence obtained from the sediment clustered in the Euryarchaeota indicating that M. burtonii-related strains in the area of Calyptogena communities may contribute to production of methane in this environment. From these results, we propose a possible model of sulfur circulation within the microbial community and that of Calyptogena clams in the cold-seep environment.

  12. Phylogenetic diversity of dissimilatory sulfite reductase genes from deep-sea cold seep sediment.

    PubMed

    Fukuba, Tatsuhiro; Ogawa, Mari; Fujii, Teruo; Naganuma, Takeshi

    2003-01-01

    The phylogenetic diversity of dissimilatory sulfite reductase (DSR, EC 1.8.99.3) alpha-subunit genes from a deep-sea cold seep was analyzed. Bulk genomic DNA was extracted from the cold seep sediment and used for amplification by polymerase chain reaction (PCR) of DSR alpha-subunit gene. Two sizes of PCR products, 1.4 kb (expected) and 1.3 kb (unexpected), were amplified. Sixteen clones of the 1.4-kb amplicons and 16 clones of 1.3-kb amplicons, a total of 32 clones, were obtained and grouped into operational DSR units (ODUs) based on restriction fragment length polymorphism (RFLP) by digestion with HaeIII and MboI. A total of 14 ODUs, i.e., 5 ODUs from 1.4-kb amplicon clones and 9 ODUs from 1.3-kb amplicon clones, were recovered. About 400 bp of the 5' ends of all the clones was sequenced and validated the RFLP-based ODU grouping. All the 5'-end 400-bp sequences of ODUs, even from the 1.3-kb amplicons, showed the characteristic DSR amino acid sequence motifs. The ODUs from 1.4-kb amplicons were closely related to the delta-Proteobacterial lineage with the DSR genes from epsilon-Proteobacterial epibionts of the hot vent worm Alvinella pompejana. The ODUs from 1.3-kb amplicons were mostly related to the unknown but possibly archaeal lineage. The diversity of the DSR genes may indicate the diversity of sulfate reducers in the seep sediment as well as the complexity of electron donors including methane.

  13. Mercury concentrations, speciation, and isotopic composition in sediment from a cold seep in the northern Gulf of Mexico.

    PubMed

    Brown, Garry; Sleeper, Kenneth; Johnson, Marcus W; Blum, Joel D; Cizdziel, James V

    2013-12-15

    Total-Hg, monomethylmercury (MMHg), and mercury isotopic composition was determined in sediment from a cold seep and background sites in the northern Gulf of Mexico (nGoM). Total-Hg averaged 50 ng/g (n=28), ranged from 31 to 67 ng/g, and decreased with depth (0-15 cm). MMHg averaged 0.91 ng/g (n=18), and ranged from 0.2 to 1.9 ng/g. There was no significant difference for total-Hg or MMHg between cold seep and background sites. δ(202)Hg ranged from -0.5 to -0.8‰ and becomes more negative with depth (r=0.989). Mass independent fractionation (Δ(199)Hg) was small but consistently positive (0.04-0.12‰); there was no difference between cold seeps (Δ(199)Hg = +0.09±0.03; n=7, 1SD) and background sites (Δ(199)Hg=+0.07±0.02; n=5, 1SD). This suggests that releases of hydrocarbons at the cold seep do not significantly alter Hg levels, and that cold seeps are likely not major sources of MMHg to nGoM waters.

  14. Integrated metagenomic and metaproteomic analyses of an ANME-1-dominated community in marine cold seep sediments.

    PubMed

    Stokke, Runar; Roalkvam, Irene; Lanzen, Anders; Haflidason, Haflidi; Steen, Ida H

    2012-05-01

    Sulfate-reducing methanotrophy by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) is a major biological sink of methane in anoxic methane-enriched marine sediments. The physiology of a microbial community dominated by free-living ANME-1 at 14-16 cm below the seafloor in the G11 pockmark at Nyegga was investigated by integrated metagenomic and metaproteomic approaches. Total DNA was subjected to 454-pyrosequencing (829 527 reads), and 16.6 Mbp of sequence information was assembled into 27352 contigs. Taxonomic analysis supported a high abundance of Euryarchaea (70%) with 66% of the assembled metagenome belonging to ANME-1. Extracted sediment proteins were separated in two dimensions and subjected to mass spectrometry (LTQ-Orbitrap XL). Of 356 identified proteins, 245 were expressed by ANME-1. These included proteins for cold-adaptation and production of gas vesicles, reflecting both the adaptation of the ANME-1 community to a permanently cold environment and its potential for positioning in specific sediment depths respectively. In addition, key metabolic enzymes including the enzymes in the reverse methanogenesis pathway (except N(5) ,N(10) -methylene-tetrahydromethanopterin reductase), heterodisulfide reductases and the F(420) H(2) :quinone oxidoreductase (Fqo) complex were identified. A complete dissimilatory sulfate reduction pathway was expressed by sulfate-reducing Deltaproteobacteria. Interestingly, an APS-reductase comprising Gram-positive SRB and related sequences were identified in the proteome. Overall, the results demonstrated that our approach was effective in assessing in situ metabolic processes in cold seep sediments.

  15. Shimia sagamensis sp. nov., a marine bacterium isolated from cold-seep sediment.

    PubMed

    Nogi, Yuichi; Mori, Kozue; Uchida, Hiromi; Hatada, Yuji

    2015-09-01

    A novel marine bacterial strain designated JAMH 011(T) was isolated from the cold-seep sediment in Sagami Bay, Japan. Cells were Gram-stain-negative, rod-shaped, non-spore-forming, aerobic chemo-organotrophs and motile by means of a single polar flagellum. Growth occurred at temperatures below 31 °C, with the optimum at 25 °C. The major respiratory quinone was Q-10. The predominant fatty acid was C18 : 1ω7c. On the basis of 16S rRNA gene sequence analysis, the isolated strain was closely affiliated with members of the genus Shimia in the class Alphaproteobacteria, and the 16S rRNA gene sequence similarity of the novel isolate with the type strain of the closest related species, Shimia haliotis WM35(T), was 98.1%. The DNA G+C content of the novel strain was 57.3 mol%. The hybridization values for DNA-DNA relatedness between strain JAMH 011(T) and reference strains belonging to the genus Shimia were less than 9.4 ± 0.7%. Based on differences in taxonomic characteristics, the isolated strain represents a novel species of the genus Shimia, for which the name Shimia sagamensis sp. nov. is proposed. The type strain is JAMH 011(T) ( = JCM 30583(T) = DSM 29734(T)).

  16. Thalassobius abyssi sp. nov., a marine bacterium isolated from the cold-seep sediment.

    PubMed

    Nogi, Yuichi; Mori, Kozue; Makita, Hiroko; Hatada, Yuji

    2015-11-09

    A novel marine bacterial strain designated JAMH 043T was isolated from the cold-seep sediment in Sagami Bay, Japan. Cells were Gram-negative, rod-shaped, non-motile and aerobic chemo-organotrophs. The cells of the isolate grew optimally at 25 °C, pH 7.0-7.5, and with 3% (w/v) NaCl. The major respiratory quinone was Q-10. The predominant fatty acid was C18:1ω7c. On the basis of 16S rRNA gene sequence analysis, the isolated strain was closely affiliated with members of the genus Thalassobius in the class Alphaproteobacteria, and the 16S rRNA gene sequence similarity of the novel isolate with the type strain of closest related species, Thalassobius aestuarii JC2049T, was 98.4 %. The DNA G+C content of the novel strain was 58.0 mol%. The hybridization values for DNA-DNA relatedness between strain JAMH043T and reference strains belonging to the genus Thalassobius were less than 14.1±2.2 %. Based on differences in taxonomic characteristics, the isolated strain represents a novel species of the genus Thalassobius, for which the name Thalassobius abyssi sp. nov. is proposed. Type strain is JAMH 043T (=JCM 30900T =DSMZ 100673T).

  17. Methane-metabolizing microbial communities in sediments of the Haima cold seep area, northwest slope of the South China Sea.

    PubMed

    Niu, Mingyang; Fan, Xibei; Zhuang, Guangchao; Liang, Qianyong; Wang, Fengping

    2017-09-01

    Cold seeps are widespread chemosynthetic ecosystems in the deep-sea environment, and cold seep microbial communities of the South China Sea are poorly constrained. Here we report on the archaeal communities, particularly those involved in methane metabolization, in sediments of a newly discovered cold seep (named 'Haima') on the northwest slope of the South China Sea. Archaeal diversity, abundance and distribution were investigated in two piston cores collected from a seep area (QDN-14B) and a non-seep control site (QDN-31B). Geochemical investigation of the QDN-14B core identified an estimated sulfate-methane transition zone (Estimated SMTZ) at 300-400 cm below sea floor (cmbsf), where a high abundance of anaerobic methane-oxidizing archaea (ANME) occurred, as revealed by analysis of the 16S rRNA gene and the gene (mcrA) encoding the α-subunit of the key enzyme methyl-coenzyme M reductase. ANME-2a/b was predominant in the upper and middle layers of the estimated SMTZ, whereas ANME-1b outcompeted ANME-2 in the sulfate-depleted bottom layers of the estimated SMTZ and the methanogenic zone. Fine-scale phylogenetic analysis further divided the ANME-1b group into three subgroups with different distribution patterns: ANME-1bI, ANME-1bII and ANME-1bIII. Multivariate analyses indicated that dissolved inorganic carbon and sulfate may be important factors controlling the composition of the methane-metabolizing community. Our study on ANME niche separation and interactions with other archaeal groups improves our understanding of the metabolic diversity and flexibility of ANME, and the findings further suggest that ANME subgroups may have evolved diversified/specified metabolic capabilities other than syntrophic anaerobic oxidation of methane coupled with sulfate reduction in marine sediments. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Molecular phylogenetic analyses of reverse-transcribed bacterial rRNA obtained from deep-sea cold seep sediments.

    PubMed

    Inagaki, Fumio; Sakihama, Yuri; Inoue, Akira; Kato, Chiaki; Horikoshi, Koki

    2002-05-01

    A depth profile of naturally occurring bacterial community structures associated with the deep-sea cold seep push-core sediment in the Japan Trench at a depth of 5343 m were evaluated using molecular phylogenetic analyses of RNA reverse transcription-PCR (RT-PCR) amplified 16S crDNA fragments. A total of 137 clones of bacterial crDNA (complimentary rDNA) phylotypes (phylogenetic types) obtained at three different depths (2-4, 8-10 and 14-16 cm) were identified in partial crDNA sequencings. crDNA phylotypes from the cold seep sediment were dominantly composed of delta- and epsilon-Proteobacteria (36% and 42% respectively). Phylotype analysis of crDNA clone libraries and terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the majority of bacterial components shifted from delta- Proteobacteria to epsilon-Proteobacteria with increasing depth. Among the delta-proteobacterial crDNA clones, the sequences related to the genus Desulfosarcina were dominant. Almost all sequences of crDNA belonging to epsilon-Proteobacteria were affiliated with the same cluster (epsilon-CSG: epsilon-proteobacterial cold seep group), and were closely related with rDNA sequences from deep-sea hydrothermal vent environments.

  19. Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep

    USGS Publications Warehouse

    Pohlman, John W.; Riedel, Michael; Novosel, Ivana; Bauer, James E.; Canuel, Elizabeth A.; Paull, Charles K.; Coffin, Richard B.; Grabowski, Kenneth S.; Knies, David L.; Hyndman, Roy D.; Spence, George D.

    2011-01-01

    Delineating sediment organic matter origins and sediment accumulation rates at gas hydratebearing and hydrocarbon seeps is complicated by the microbial transfer of 13C-depleted and 14Cdepleted methane carbon into sedimentary pools. Sediment 13C and 14C measurements from four cores recovered at Bullseye vent on the northern Cascadia margin are used to identify methane carbon assimilation into different carbon pools. While the total organic carbon (TOC) is mostly unaltered and primarily terrigenous in origin, planktonic foraminifera and the bulk carbonate display evidence of methane overprinting. Mass balance models are applied to determine the extent to which methane overprinting increased the radiocarbon ages of the biogenic foraminifera. The corrected and calibrated foraminifera ages between sediment depths of 70 and 573 cm are from 14.9 to 15.9 ka BP, which coincides with the retreat of the late Quaternary Cordilleran Ice Sheet from Vancouver Island. Uniform TOC _13C values of -24.5 ± 0.5‰ from the upper 8 meters of sediment at Bullseye vent suggest all cored material is Pleistocene-derived glacimarine material deposited as the ice edge retreated landward. Bullseye vent is located within an uplifted sediment block isolated from turbidite deposition and has been a site of non-deposition since the ice sheet retreated from the shelf. Biogeochemical implications of seep sediments being dominated by aged, organic-poor (<0.4 wt% TOC) material are that methane is the primary energy source, and microbes directly and indirectly associated with the anaerobic oxidation of methane (AOM) will dominate the seep microbial community.

  20. Geochemical Tracers and Rates of Short-Chain Alkane Production in Gulf of Mexico Cold Seep Sediments

    NASA Astrophysics Data System (ADS)

    Sibert, R.; Bernard, B. B.; Brooks, J. M.; Hunter, K.; Joye, S. B.

    2014-12-01

    The organic-rich cold seep sediments in the deep Gulf of Mexico commonly contain mixtures of light hydrocarbon gases either dissolved in pore fluids, adsorbed to sediment particles, trapped in methane ice, or as free gas. The dominant component in these natural gas mixtures is typically methane (C1), but ethane (C2) and propane (C3) are nearly always present in trace or major amounts. The ratio of C1:C2:C3 varies but C2 and C3 are typically present at single digit percent levels, whereas methane usually dominates at >80%. Methane production proceeds by at least two well-studied mechanisms: either 1) by thermocatalytic cracking of fossil organic matter, or 2) as a direct product of microbial metabolism, methanogenesis. In contrast, ethane and propane production in deep-sea sediments has been historically attributed only to thermocatalytic processes. However, limited data suggests production of C2/C3 compounds through the activity of archaea. Such studies of microbial- driven dynamics of C2/C3 gases (i.e. 'alkanogenesis') in cold seep sediments are rare. Furthermore, the identities of potential substrates are poorly constrained and no attempt has been made to quantify production rates of C2/C3 gases. However, carbon isotopic data on ethane and propane from deep cores from the Gulf of Mexico suggest alkanogenesis at depth in the sediment column and alkane oxidation in uppermost oxidant-rich sediments. Here, we present the results of a series of incubation experiments using sediment slurries culled from GC600, one of the most prolific natural oil and gas seeps in the Gulf of Mexico. Rates of both alkane production and oxidation were measured under a variety of conditions to assess the net rates of alkane production and elucidate the driving microbiological mechanisms and controls on the central processes of >C1 alkane cycling in cold seep sediments. Microbial processes are important both in terms of alkane production and oxidation, raising many questions as to the

  1. Molecular evidence that phylogenetically diverged ciliates are active in microbial mats of deep-sea cold-seep sediment.

    PubMed

    Takishita, Kiyotaka; Kakizoe, Natsuki; Yoshida, Takao; Maruyama, Tadashi

    2010-01-01

    Cold seeps are areas of the seafloor where hydrogen sulfide- and methane-rich fluid seepage occurs, often sustaining chemosynthetic ecosystems. It is well known that both archaea and bacteria oxidize sulfides and methane to produce chemical energy and that several endemic animals use this energy to thrive in cold seeps. On the other hand, there is little knowledge regarding diversity and ecology of microbial eukaryotes in this ecosystem. In this study we isolated environmental RNA and DNA from microbial mats of cold-seep sediment in Sagami Bay, Japan, and retrieved eukaryotic small-subunit ribosomal RNA sequences with polymerase chain reaction methods followed by clone library construction. Most RNA-derived clones obtained were from ciliates, although DNA-derived clones were mainly from the fungus Cryptococcus curvatus, suggesting that ciliates are active in the environment. The ciliate sequences were phylogenetically diverse, and represented eight known class lineages as well as undesignated lineages. Because most ciliates are bacterivorous, it is highly likely that the ciliates for which sequences were recovered play a role in the food web of this ecosystem as grazers of microbial mats. In addition, given that the environment studied is under highly reduced (anoxic) conditions, based on the prokaryotic community structure deduced from T-RFLP profiles, the ciliates detected may be obligatory or facultative anaerobes.

  2. Authigenesis of vivianite as influenced by methane-induced sulfidization in cold-seep sediments off southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Hsu, Ta-Wei; Jiang, Wei-Teh; Wang, Yunshuen

    2014-08-01

    Authigenesis of iron-rich phosphate nodules occurs in iron-rich cold-seep sediments (MD052911 core) at Yung-An Ridge offshore southwestern Taiwan. Raman, FTIR, and quantitative X-ray energy-dispersive spectroscopic analyses indicate that the phosphate mineral is vivianite (or barićite) and shows Fe/Mg molar ratios spanning from ca. 0.6 to 4.0 and a general down core trend of increasing Fe/Mg ratios. The formation of vivianite is limited to a depth interval of 13-17 mbsf (meters below seafloor) and is most prominent at ∼16 mbsf in association with high dissolved iron concentrations and depleted dissolved sulfide below a peak sulfidization zone (enriched in mackinawite and greigite). Alternate growths of vivianite and iron monosulfides and compositional zoning with Mg enriched towards the peripheries of individual nodules occur in the transition from the zone of vivianite mineralization to the sulfidization zone. The crystallization of vivianite below the sulfidization front could have been favored by scavenging of downward diffusive dissolved sulfide from pore waters in the sulfidization zone. Alternate growths and overlapping of the zones of iron monosulfides and vivianite can be attributed to fluctuations of the sulfidization front and methane flux. The discovery of vivianite in the Yung-An Ridge sediments implies that authigenic vivianite can be an important sink for phosphorus burial in cold-seep sediments that have high reactive-iron contents and high sedimentation rates.

  3. Multiple archaeal groups mediate methane oxidation in anoxic cold seep sediments.

    PubMed

    Orphan, Victoria J; House, Christopher H; Hinrichs, Kai-Uwe; McKeegan, Kevin D; DeLong, Edward F

    2002-05-28

    No microorganism capable of anaerobic growth on methane as the sole carbon source has yet been cultivated. Consequently, information about these microbes has been inferred from geochemical and microbiological observations of field samples. Stable isotope analysis of lipid biomarkers and rRNA gene surveys have implicated specific microbes in the anaerobic oxidation of methane (AOM). Here we use combined fluorescent in situ hybridization and secondary ion mass spectrometry analyses, to identify anaerobic methanotrophs in marine methane-seep sediments. The results provide direct evidence for the involvement of at least two distinct archaeal groups (ANME-1 and ANME-2) in AOM at methane seeps. Although both archaeal groups often occurred in direct physical association with bacteria, they also were observed as monospecific aggregations and as single cells. The ANME-1 archaeal group more frequently existed in monospecific aggregations or as single filaments, apparently without a bacterial partner. Bacteria associated with both archaeal groups included, but were not limited to, close relatives of Desulfosarcina species. Isotopic analyses suggest that monospecific archaeal cells and cell aggregates were active in anaerobic methanotrophy, as were multispecies consortia. In total, the data indicate that the microbial species and biotic interactions mediating anaerobic methanotrophy are diverse and complex. The data also clearly show that highly structured ANME-2/Desulfosarcina consortia are not the sole entities responsible for AOM at marine methane seeps. Other microbial groups, including ANME-1 archaea, are capable of anaerobic methane consumption either as single cells, in monospecific aggregates, or in multispecies consortia.

  4. Cold-seep-like macrofaunal communities in organic- and sulfide-rich sediments of the Congo deep-sea fan

    NASA Astrophysics Data System (ADS)

    Olu, K.; Decker, C.; Pastor, L.; Caprais, J.-C.; Khripounoff, A.; Morineaux, M.; Ain Baziz, M.; Menot, L.; Rabouille, C.

    2017-08-01

    Methane-rich fluids arising from organic matter diagenesis in deep sediment layers sustain chemosynthesis-based ecosystems along continental margins. This type of cold seep develops on pockmarks along the Congo margin, where fluids migrate from deep-buried paleo-channels of the Congo River, acting as reservoirs. Similar ecosystems based on shallow methane production occur in the terminal lobes of the present-day Congo deep-sea fan, which is supplied by huge quantities of primarily terrestrial material carried by turbiditic currents along the 800 km channel, and deposited at depths of up to nearly 5000 m. In this paper, we explore the effect of this carbon enrichment of deep-sea sediments on benthic macrofauna, along the prograding lobes fed by the current active channel, and on older lobes receiving less turbiditic inputs. Macrofaunal communities were sampled using either USNEL cores on the channel levees, or ROV blade cores in the chemosynthesis-based habitats patchily distributed in the active lobe complex. The exceptionally high organic content of the surface sediment in the active lobe complex was correlated with unusual densities of macrofauna for this depth, enhanced by a factor 7-8, compared with those of the older, abandoned lobe, whose sediment carbon content is still higher than in Angola Basin at same depth. Macrofaunal communities, dominated by cossurid polychaetes and tanaids were also more closely related to those colonizing low-flow cold seeps than those of typical deep-sea sediment. In reduced sediments, microbial mats and vesicomyid bivalve beds displayed macrofaunal community patterns that were similar to their cold-seep counterparts, with high densities, low diversity and dominance of sulfide-tolerant polychaetes and gastropods in the most sulfidic habitats. In addition, diversity was higher in vesicomyid bivalve beds, which appeared to bio-irrigate the upper sediment layers. High beta-diversity is underscored by the variability of geochemical

  5. New insight into stratification of anaerobic methanotrophs in cold seep sediments.

    PubMed

    Roalkvam, Irene; Jørgensen, Steffen Leth; Chen, Yifeng; Stokke, Runar; Dahle, Håkon; Hocking, William Peter; Lanzén, Anders; Haflidason, Haflidi; Steen, Ida Helene

    2011-11-01

    Methane seepages typically harbor communities of anaerobic methane oxidizers (ANME); however, knowledge about fine-scale vertical variation of ANME in response to geochemical gradients is limited. We investigated microbial communities in sediments below a white microbial mat in the G11 pockmark at Nyegga by 16S rRNA gene tag pyrosequencing and real-time quantitative PCR. A vertical stratification of dominating ANME communities was observed at 4 cmbsf (cm below seafloor) and below in the following order: ANME-2a/b, ANME-1 and ANME-2c. The ANME-1 community was most numerous and comprised single or chains of cells with typical rectangular morphology, accounting up to 89.2% of the retrieved 16S rRNA gene sequences. Detection rates for sulfate-reducing Deltaproteobacteria possibly involved in anaerobic oxidation of methane were low throughout the core. However, a correlation in the abundance of Candidate division JS-1 with ANME-2 was observed, indicating involvement in metabolisms occurring in ANME-2-dominated horizons. The white microbial mat and shallow sediments were dominated by organisms affiliated with Sulfurovum (Epsilonproteobacteria) and Methylococcales (Gammaproteobacteria), suggesting that aerobic oxidation of sulfur and methane is taking place. In intermediate horizons, typical microbial groups associated with methane seeps were recovered. The data are discussed with respect to co-occurring microbial assemblages and interspecies interactions.

  6. Characteristics and possible origin of native aluminum in cold seep sediments from the northeastern South China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Huang, Chi-Yue; Zhao, Meixun; Yan, Wen; Chien, Chih-Wei; Chen, Muhong; Yang, Huaping; Machiyama, Hideaki; Lin, Saulwood

    2011-01-01

    Although native aluminum (Al°) has been reported to occur in various geological settings for more than 20 locations but its mechanism of formation still remains to be elucidated. We report the occurrence and characterization of Al° particles recovered from the surface sediment (CF4) and a short core sediment (ROV-G, 37 cm length) obtained at cold seeps in the northeastern continental slope (NCS) of the South China Sea (SCS). X-ray diffraction analysis shows that the collected particles are metallic aluminum with the unit cell edge a of 4.059 ± 0.005 Å (CF4#2) and 4.029 ± 0.004 Å (T26-28#2, ROV-G). The Al° particles occur as spherules, irregular plates and elongated forms with typical lamellar structures. Their chemical compositions are 95.07-99.84% Al (the average values is 98.42%) with very small amounts of Si, Fe, Ti, S, Zn, Mg, Ca, K, Na, Cu, Co and P, and are similar to Al° particles from the East Pacific Rise and the Central Indian Basin but differ markedly to those from other locations. After ruling out several possibilities of Al° sources and mechanism of formation, an alternative cold seep mechanism is proposed for the origin of Al° in the SCS. During the processes of anaerobic oxidation of methane (AOM) and pyrite formation, high H 2S and H 2 partial pressures result in strong reducing micro-environments, under which Al(OH)4- is reduced to its metallic state by the microbial-bacterial processes.

  7. Presence and diversity of anammox bacteria in cold hydrocarbon-rich seeps and hydrothermal vent sediments of the Guaymas Basin.

    PubMed

    Russ, Lina; Kartal, Boran; Op den Camp, Huub J M; Sollai, Martina; Le Bruchec, Julie; Caprais, Jean-Claude; Godfroy, Anne; Sinninghe Damsté, Jaap S; Jetten, Mike S M

    2013-01-01

    Hydrothermally active sediments are highly productive, chemosynthetic areas which are characterized by the rapid turnover of particulate organic matter under extreme conditions in which ammonia is liberated. These systems might be suitable habitats for anaerobic ammonium oxidizing (anammox) bacteria but this has not been investigated in detail. Here we report the diversity and abundance of anammox bacteria in sediments that seep cold hydrocarbon-rich fluids and hydrothermal vent areas of the Guaymas Basin in the Cortés Sea using the unique functional anammox marker gene, hydrazine synthase (hzsA). All clones retrieved were closely associated to the "Candidatus Scalindua" genus. Phylogenetic analysis revealed two distinct clusters of hzsA sequences (Ca. Scalindua hzsA cluster I and II). Comparison of individual sequences from both clusters showed that several of these sequences had a similarity as low as 76% on nucleotide level. Based on the analysis of this phylomarker, a very high interspecies diversity within the marine anammox group is apparent. Absolute numbers of anammox bacteria in the sediments samples were determined by amplification of a 257 bp fragment of the hszA gene in a qPCR assay. The results indicate that numbers of anammox bacteria are generally higher in cold hydrocarbon-rich sediments compared to the vent areas and the reference zone. Ladderanes, lipids unique to anammox bacteria were also detected in several of the sediment samples corroborating the hzsA analysis. Due to the high concentrations of reduced sulfur compounds and its potential impact on the cycling of nitrogen we aimed to get an indication about the key players in the oxidation of sulfide in the Guaymas Basin sediments using the alpha subunit of the adenosine-5'-phosphosulfate (APS) reductase (aprA). Amplification of the aprA gene revealed a high number of gammaproteobacterial aprA genes covering the two sulfur-oxidizing bacteria aprA lineages as well as sulfate-reducers.

  8. Presence and diversity of anammox bacteria in cold hydrocarbon-rich seeps and hydrothermal vent sediments of the Guaymas Basin

    PubMed Central

    Russ, Lina; Kartal, Boran; op den Camp, Huub J. M.; Sollai, Martina; Le Bruchec, Julie; Caprais, Jean-Claude; Godfroy, Anne; Sinninghe Damsté, Jaap S.; Jetten, Mike S. M.

    2013-01-01

    Hydrothermally active sediments are highly productive, chemosynthetic areas which are characterized by the rapid turnover of particulate organic matter under extreme conditions in which ammonia is liberated. These systems might be suitable habitats for anaerobic ammonium oxidizing (anammox) bacteria but this has not been investigated in detail. Here we report the diversity and abundance of anammox bacteria in sediments that seep cold hydrocarbon-rich fluids and hydrothermal vent areas of the Guaymas Basin in the Cortés Sea using the unique functional anammox marker gene, hydrazine synthase (hzsA). All clones retrieved were closely associated to the “Candidatus Scalindua” genus. Phylogenetic analysis revealed two distinct clusters of hzsA sequences (Ca. Scalindua hzsA cluster I and II). Comparison of individual sequences from both clusters showed that several of these sequences had a similarity as low as 76% on nucleotide level. Based on the analysis of this phylomarker, a very high interspecies diversity within the marine anammox group is apparent. Absolute numbers of anammox bacteria in the sediments samples were determined by amplification of a 257 bp fragment of the hszA gene in a qPCR assay. The results indicate that numbers of anammox bacteria are generally higher in cold hydrocarbon-rich sediments compared to the vent areas and the reference zone. Ladderanes, lipids unique to anammox bacteria were also detected in several of the sediment samples corroborating the hzsA analysis. Due to the high concentrations of reduced sulfur compounds and its potential impact on the cycling of nitrogen we aimed to get an indication about the key players in the oxidation of sulfide in the Guaymas Basin sediments using the alpha subunit of the adenosine-5′-phosphosulfate (APS) reductase (aprA). Amplification of the aprA gene revealed a high number of gammaproteobacterial aprA genes covering the two sulfur-oxidizing bacteria aprA lineages as well as sulfate

  9. Functional diversity patterns of abyssal nematodes in the Eastern Mediterranean: A comparison between cold seeps and typical deep sea sediments

    NASA Astrophysics Data System (ADS)

    Kalogeropoulou, V.; Keklikoglou, K.; Lampadariou, N.

    2015-04-01

    Spatial patterns in deep sea nematode biological trait composition and functional diversity were investigated between chemosynthetic and typical deep sea ecosystems as well as between different microhabitats within the chemosynthetic ecosystems, in the Eastern Mediterranean. The chemosynthetic ecosystems chosen were two mud volcanoes, Napoli at 1950 m depth and Amsterdam at 2040 m depth which are cold seeps characterized by high chemosynthetic activity and spatial heterogeneity. Typical deep sea ecosystems consisted of fine-grained silt-clay sediments which were collected from three areas located in the south Ionian Sea at 2765 to 2840 m depth, the southern Cretan margin at 1089 to 1998 m depth and the Levantine Sea at 3055 to 3870 m depth. A range of biological traits (9 traits; 31 categories) related to buccal morphology, tail shape, body size, body shape, life history strategy, sediment position, cuticle morphology, amphid shape and presence of somatic setae were combined to identify patterns in the functional composition of nematode assemblages between the two habitats, the two mud volcanoes (macroscale) and between the microhabitats within the mud volcanoes (microscale). Data on trait correspondence was provided by biological information on species and genera. A total of 170 nematode species were allocated in 67 different trait combinations, i.e. functional groups, based on taxonomic, morphological and behavioral characteristics. The Biological Trait Analysis (BTA) revealed significant differences between the mud volcanoes and the typical deep sea sediments indicating the presence of different biological functions in ecologically very different environments. Moreover, chemosynthetic activity and habitat heterogeneity within mud volcanoes enhance the presence of different biological and ecological functions in nematode assemblages of different microhabitats. Functional diversity and species richness patterns varied significantly across the different

  10. Psychromonas kaikoae sp. nov., a novel from the deepest piezophilic bacterium cold-seep sediments in the Japan Trench.

    PubMed

    Nogi, Yuichi; Kato, Chiaki; Horikoshi, Koki

    2002-09-01

    Two strains of obligately piezophilic bacteria were isolated from sediment collected from the deepest cold-seep environment with chemosynthesis-based animal communities within the Japan Trench, at a depth of 7434 m. The isolated strains, JT7301 and JT7304T, were closely affiliated with members of the genus Psychromonas on the basis of 16S rDNA sequence analysis. Hybridization values for DNA-DNA relatedness between these strains and the Psychromonas antarctica reference strain were significantly lower than that accepted as the phylogenetic definition of a species. The optimal temperature and pressure for growth of the isolates were 10 degrees C and 50 MPa and they produced both eicosapentaenoic acid (C20:5omega3) and docosahexaenoic acid (C22:6) in the membrane layer. Based on the taxonomic differences observed, the isolated strains appear to represent a novel obligately piezophilic Psychromonas species. The name Psychromonas kaikoae sp. nov. (type strain JT7304T = JCM 11054T = ATCC BAA-363T) is proposed. This is the first proposed obligately piezophilic species of the genus Psychromonas.

  11. Molecular evidence that deep-branching fungi are major fungal components in deep-sea methane cold-seep sediments.

    PubMed

    Nagahama, Takahiko; Takahashi, Eriko; Nagano, Yuriko; Abdel-Wahab, Mohamed A; Miyazaki, Masayuki

    2011-08-01

    The motile cells of chytrids were once believed to be relics from the time before the colonization of land by fungi. However, the majority of chytrids had not been found in marine but freshwater environments. We investigated fungal diversity by a fungal-specific PCR-based analysis of environmental DNA in deep-sea methane cold-seep sediments, identifying a total of 35 phylotypes, 12 of which were early diverging fungi (basal fungi, ex 'lower fungi'). The basal fungi occupied a major portion of fungal clones. These were phylogenetically placed into a deep-branching clade of fungi and the LKM11 clade that was a divergent group comprised of only environmental clones from aquatic environments. As suggested by Lara and colleagues, species of the endoparasitic genus Rozella, being recently considered of the earliest branching taxa of fungi, were nested within the LKM11 clade. In the remaining 23 phylotypes identified as the Dikarya, the majority of which were similar to those which appeared in previously deep-sea studies, but also highly novel lineages associated with Soil Clone Group I (SCGI), Entorrhiza sp. and the agaricomycetous fungi were recorded. The fungi of the Dikarya may play a role in the biodegradation of lignin and lignin-derived materials in deep-sea, because the characterized fungal species related to the frequent phylotypes within the Dikarya have been reported to possess an ability to degrade lignin.

  12. Diversity of microbial eukaryotes in sediment at a deep-sea methane cold seep: surveys of ribosomal DNA libraries from raw sediment samples and two enrichment cultures.

    PubMed

    Takishita, Kiyotaka; Yubuki, Naoji; Kakizoe, Natsuki; Inagaki, Yuji; Maruyama, Tadashi

    2007-07-01

    Recent culture-independent surveys of eukaryotic small-subunit ribosomal DNA (SSU rDNA) from many environments have unveiled unexpectedly high diversity of microbial eukaryotes (microeukaryotes) at various taxonomic levels. However, such surveys were most probably biased by various technical difficulties, resulting in underestimation of microeukaryotic diversity. In the present study on oxygen-depleted sediment from a deep-sea methane cold seep of Sagami Bay, Japan, we surveyed the diversity of eukaryotic rDNA in raw sediment samples and in two enrichment cultures. More than half of all clones recovered from the raw sediment samples were of the basidiomycetous fungus Cryptococcus curvatus. Among other clones, phylotypes of eukaryotic parasites, such as Apicomplexa, Ichthyosporea, and Phytomyxea, were identified. On the other hand, we observed a marked difference in phylotype composition in the enrichment samples. Several phylotypes belonging to heterotrophic stramenopiles were frequently found in one enrichment culture, while a phylotype of Excavata previously detected at a deep-sea hydrothermal vent dominated the other. We successfully established a clonal culture of this excavate flagellate. Since these phylotypes were not identified in the raw sediment samples, the approach incorporating a cultivation step successfully found at least a fraction of the "hidden" microeukaryotic diversity in the environment examined.

  13. Microbial Diversity of Cold-Seep Sediments in Sagami Bay, Japan as Determined by 16S rDNA and Lipid Analyses

    NASA Astrophysics Data System (ADS)

    Fang, J.; Arakawa, S.; Kato, C.; Schouten, S.

    2006-12-01

    Microbial communities in Calyptogena sediment and microbial mats of Sagami Bay, Japan were characterized by using 16S rDNA sequencing and lipid biomarker analysis. Characterization of 16S rDNA isolated from these samples suggested a predominance of bacterial phylotypes related to γ- (57-64%) and δ-subclasses (27-29%) of the Proteobacteria. The ɛ-subclass of the Proteobacteria commonly found in cold seeps and hydrothermal vents were only detected in the microbial mat sample. There are significantly different archaeal phylotypes between Calyptogena sediment and microbial mat; the former contains only Crenarchaeota clones (100% of the total archaeal clones) and the latter exclusively Euryarchaeota clones including the ANME-2a and ANME-2c archaeal groups. Many of these lineages are as yet uncultured and undescribed groups of bacteria and archaea. Phospholipid fatty acid analysis suggests the presence of sulfate-reducing and sulfur-oxidizing bacteria. Results of intact glyceryl dialkyl glyceryl tetraether (GDGT) lipid analysis indicate the presence of nonthermophilic marine planktonic archaea. These results suggest that the microbial community in the Sagami Bay seep site is distinct from previously characterized cold seep environments.

  14. Microbial diversity of cold-seep sediments in Sagami Bay, Japan, as determined by 16S rRNA gene and lipid analyses.

    PubMed

    Fang, Jiasong; Shizuka, Arakawa; Kato, Chiaki; Schouten, Stefan

    2006-09-01

    Microbial communities in Calyptogena sediment and microbial mats of Sagami Bay, Japan, were characterized using 16S rRNA gene sequencing and lipid biomarker analysis. Characterization of 16S rRNA gene isolated from these samples suggested a predominance of bacterial phylotypes related to Gammaproteobacteria (57-64%) and Deltaproteobacteria (27-29%). The Epsilonproteobacteria commonly found in cold seeps and hydrothermal vents were only detected in the microbial mat sample. Significantly different archaeal phylotypes were found in Calyptogena sediment and microbial mats; the former contained only Crenarchaeota clones (100% of the total archaeal clones) and the latter exclusively Euryarchaeota clones, including the anaerobic oxidation of methane archaeal groups ANME-2a and ANME-2c. Many of these lineages are as yet uncultured and undescribed groups of bacteria and archaea. Phospholipid fatty acid analysis suggested the presence of sulphate-reducing and sulphur-oxidizing bacteria. Results of intact glyceryl dialkyl glyceryl tetraether lipid analysis indicated the presence of nonthermophilic marine planktonic archaea. These results suggest that the microbial community in the Sagami Bay seep site is distinct from previously characterized cold-seep environments.

  15. Community Proteogenomics of a Cold-methane Seep Sediment at Nyegga, Mid-Norwegian Margin

    NASA Astrophysics Data System (ADS)

    Stokke, R.; Roalkvam, I.; Lanzen, A.; Chen, Y.; Haflidason, H.; Steen, I.

    2010-12-01

    Anaerobic oxidation of methane (AOM) is limited to anoxic environments and differs in its rates from a few pmol cm-3day-1 in subsurface SMTZ (sulfate-methane transition zone) of deep margins, to a few μmol cm-3 day-1 in surface sediments above gas hydrates [1]. This process is catalyzed by consortia of anaerobic methane oxidizing archaea (ANME) in association with sulfate-reducing bacteria. The Nyegga area is located on the Mid-Norwegian continental slope at the northern flank of the Storegga Slide at 700-800 mbsl. Hundreds of pockmarks are widespread on the seabed in Nyegga and sub-zero temperatures (-0.7 °C), and pingo-structures within the pockmarks are indicators of active fluid flow locations. Preliminary microbial and geochemical profiling of a 22 cm push-core within the G11 pockmark gave strong indications of an ANME-1 dominated community at 14-16 cmbsf. In light of these findings we submitted extracted DNA to 454-pyrosequencing. Sequencing data (829,527 reads) was assembled using the Newbler v2.3, resulting in 13,151 contigs (357,530 reads) over 500 bp with the longest contig being 24,521 bp. MEGAN taxonomic analysis supported the high abundance of Euryarchaea (70%) with 66% of the assembled metagenome belonging to ANME-1. In order to obtain functional information of the ANME-1 community, protein extraction protocols from sediment samples was established. Extracted proteins was separated on a large (18cm) 1D-SDS-PAGE and subsequently cut in 30 gel slices. Peptides extracted after In-gel tryptic digest was injected into an Ultimate 3000 nanoLC system connected to a linear quadropole ion trap-orbitrap (LTQ-Orbitrap XL) mass spectrometer equipped with a nanoelectrospray ion source. A custom database of open reading frames (ORFs) from the metagenome including known contaminants such as trypsin and human keratin was search against using Mascot 2.2. IRMa tool box [2] was used in peptide validation and peptides whose score >= 25.0 (i.e avg identity, p<0.05) and

  16. Molecular phylogenetic and chemical analyses of the microbial mats in deep-sea cold seep sediments at the northeastern Japan Sea.

    PubMed

    Arakawa, Shizuka; Sato, Takako; Sato, Rumi; Zhang, Jing; Gamo, Toshitaka; Tsunogai, Urumu; Hirota, Akinari; Yoshida, Yasuhiko; Usami, Ron; Inagaki, Fumio; Kato, Chiaki

    2006-08-01

    Microbial communities inhabiting deep-sea cold seep sediments at the northeastern Japan Sea were characterized by molecular phylogenetic and chemical analyses. White patchy microbial mats were observed along the fault offshore the Hokkaido Island and sediment samples were collected from two stations at the southern foot of the Shiribeshi seamount (M1 site at a depth of 2,961 m on the active fault) and off the Motta Cape site (M2 site at a depth of 3,064 m off the active fault). The phylogenetic and terminal-restriction fragment polymorphism analyses of PCR-amplified 16S rRNA genes revealed that microbial community structures were different between two sampling stations. The members of ANME-2 archaea and diverse bacterial components including sulfate reducers within Deltaproteobacteria were detected from M1 site, indicating the occurrence of biologically mediated anaerobic oxidation of methane, while microbial community at M2 site was predominantly composed of members of Marine Crenarchaeota group I, sulfate reducers of Deltaproteobacteria, and sulfur oxidizers of Epsilonproteobacteria. Chemical analyses of seawater above microbial mats suggested that concentrations of sulfate and methane at M1 site were largely decreased relative to those at M2 site and carbon isotopic composition of methane at M1 site shifted heavier ((13)C-enriched), the results of which are consistent with molecular analyses. These results suggest that the mat microbial communities in deep-sea cold seep sediments at the northeastern Japan Sea are significantly responsible for sulfur and carbon circulations and the geological activity associated with plate movements serves unique microbial habitats in deep-sea environments.

  17. Spatial scales of bacterial community diversity at cold seeps (Eastern Mediterranean Sea).

    PubMed

    Pop Ristova, Petra; Wenzhöfer, Frank; Ramette, Alban; Felden, Janine; Boetius, Antje

    2015-06-01

    Cold seeps are highly productive, fragmented marine ecosystems that form at the seafloor around hydrocarbon emission pathways. The products of microbial utilization of methane and other hydrocarbons fuel rich chemosynthetic communities at these sites, with much higher respiration rates compared with the surrounding deep-sea floor. Yet little is known as to the richness, composition and spatial scaling of bacterial communities of cold seeps compared with non-seep communities. Here we assessed the bacterial diversity across nine different cold seeps in the Eastern Mediterranean deep-sea and surrounding seafloor areas. Community similarity analyses were carried out based on automated ribosomal intergenic spacer analysis (ARISA) fingerprinting and high-throughput 454 tag sequencing and were combined with in situ and ex situ geochemical analyses across spatial scales of a few tens of meters to hundreds of kilometers. Seep communities were dominated by Deltaproteobacteria, Epsilonproteobacteria and Gammaproteobacteria and shared, on average, 36% of bacterial types (ARISA OTUs (operational taxonomic units)) with communities from nearby non-seep deep-sea sediments. Bacterial communities of seeps were significantly different from those of non-seep sediments. Within cold seep regions on spatial scales of only tens to hundreds of meters, the bacterial communities differed considerably, sharing <50% of types at the ARISA OTU level. Their variations reflected differences in porewater sulfide concentrations from anaerobic degradation of hydrocarbons. This study shows that cold seep ecosystems contribute substantially to the microbial diversity of the deep-sea.

  18. Spatial scales of bacterial community diversity at cold seeps (Eastern Mediterranean Sea)

    PubMed Central

    Pop Ristova, Petra; Wenzhöfer, Frank; Ramette, Alban; Felden, Janine; Boetius, Antje

    2015-01-01

    Cold seeps are highly productive, fragmented marine ecosystems that form at the seafloor around hydrocarbon emission pathways. The products of microbial utilization of methane and other hydrocarbons fuel rich chemosynthetic communities at these sites, with much higher respiration rates compared with the surrounding deep-sea floor. Yet little is known as to the richness, composition and spatial scaling of bacterial communities of cold seeps compared with non-seep communities. Here we assessed the bacterial diversity across nine different cold seeps in the Eastern Mediterranean deep-sea and surrounding seafloor areas. Community similarity analyses were carried out based on automated ribosomal intergenic spacer analysis (ARISA) fingerprinting and high-throughput 454 tag sequencing and were combined with in situ and ex situ geochemical analyses across spatial scales of a few tens of meters to hundreds of kilometers. Seep communities were dominated by Deltaproteobacteria, Epsilonproteobacteria and Gammaproteobacteria and shared, on average, 36% of bacterial types (ARISA OTUs (operational taxonomic units)) with communities from nearby non-seep deep-sea sediments. Bacterial communities of seeps were significantly different from those of non-seep sediments. Within cold seep regions on spatial scales of only tens to hundreds of meters, the bacterial communities differed considerably, sharing <50% of types at the ARISA OTU level. Their variations reflected differences in porewater sulfide concentrations from anaerobic degradation of hydrocarbons. This study shows that cold seep ecosystems contribute substantially to the microbial diversity of the deep-sea. PMID:25500510

  19. Linking Taxonomy with Environmental Geochemsitry: the Anaerobic Oxidation of Methane in Cold Seeps & deeply Buried Marine Sediments

    NASA Astrophysics Data System (ADS)

    House, C. H.; Biddle, J. F.; Lipp, J. S.; Orphan, V. J.; Hinrichs, K.

    2005-12-01

    The linking of molecular taxonomy (including 16s rRNA) to environmental geochemistry is a powerful way to work out the interactions, metabolic activities, and food webs of microorganisms in their natural setting, whether it is sediment, soil, or a water column. To this end, we developed a method for coupling an extant microorganism's genetic information with geochemical data derived from the direct analysis of its cell. FISH-SIMS combines fluorescent in-situ hybridization (FISH) with secondary ion mass spectrometry (SIMS). FISH is a culture-independent technique used to visually identify naturally occurring microorganisms by staining their ribosomal RNA. Secondary ion mass spectrometry (SIMS) is a method by which geochemical information can be obtained from microsamples. Using FISH-SIMS, a researcher can measure a target cell's isotopic or elemental composition in a mixed environment. The identification and study of methane-consuming microorganisms is an important step toward understanding the methane cycle and microbial response to methane release. The recent identification of two distinct Archaea capable of anaerobic methane oxidation was in part accomplished using FISH-SIMS. Because natural methane is highly depleted in 13C, FISH-SIMS is particularly powerful at determining if a particular cell, collected from the environment, consumed methane as a substrate for its cell carbon. This research demonstrated that both the ANME-1 and ANME-2 Archaea from the Eel River Methane Seep are highly depleted in 13C due to growth on methane. The deep marine biosphere is thought to contain abundant microbial inhabitants, estimated to be a tenth of the Earth's total biomass. Sediments from this environment were recovered during Ocean Drilling Program (ODP) Leg 201, and were analyzed by both molecular biological and organic geochemical techniques. Of particular interest in these sediments were four sulfate/methane transition zones seen at ODP Sites 1227, 1229 and 1230, two of

  20. Identification of members of the metabolically active microbial populations associated with Beggiatoa species mat communities from Gulf of Mexico cold-seep sediments.

    PubMed

    Mills, Heath J; Martinez, Robert J; Story, Sandra; Sobecky, Patricia A

    2004-09-01

    In this study, the composition of the metabolically active fraction of the microbial community occurring in Gulf of Mexico marine sediments (water depth, 550 to 575 m) with overlying filamentous bacterial mats was determined. The mats were mainly composed of either orange- or white-pigmented Beggiatoa spp. Complementary 16S ribosomal DNA (crDNA) was obtained from rRNA extracted from three different sediment depths (0 to 2, 6 to 8, and 10 to 12 cm) that had been subjected to reverse transcription-PCR amplification. Domain-specific 16S PCR primers were used to construct 12 different 16S crDNA libraries containing 333 Archaea and 329 Bacteria clones. Analysis of the Archaea clones indicated that all sediment depths associated with overlying orange- and white-pigmented microbial mats were almost exclusively dominated by ANME-2 (95% of total Archaea clones), a lineage related to the methanogenic order Methanosarcinales. In contrast, bacterial diversity was considerably higher, with the dominant phylotype varying by sediment depth. An equivalent number of clones detected at 0 to 2 cm, representing a total of 93%, were related to the gamma and delta classes of Proteobacteria, whereas clones related to delta-Proteobacteria dominated the metabolically active fraction of the bacterial community occurring at 6 to 8 cm (79%) and 10 to 12 cm (85%). This is the first phylogenetics-based evaluation of the presumptive metabolically active fraction of the Bacteria and Archaea community structure investigated along a sediment depth profile in the northern Gulf of Mexico, a hydrocarbon-rich cold-seep region.

  1. Identification of Members of the Metabolically Active Microbial Populations Associated with Beggiatoa Species Mat Communities from Gulf of Mexico Cold-Seep Sediments

    PubMed Central

    Mills, Heath J.; Martinez, Robert J.; Story, Sandra; Sobecky, Patricia A.

    2004-01-01

    In this study, the composition of the metabolically active fraction of the microbial community occurring in Gulf of Mexico marine sediments (water depth, 550 to 575 m) with overlying filamentous bacterial mats was determined. The mats were mainly composed of either orange- or white-pigmented Beggiatoa spp. Complementary 16S ribosomal DNA (crDNA) was obtained from rRNA extracted from three different sediment depths (0 to 2, 6 to 8, and 10 to 12 cm) that had been subjected to reverse transcription-PCR amplification. Domain-specific 16S PCR primers were used to construct 12 different 16S crDNA libraries containing 333 Archaea and 329 Bacteria clones. Analysis of the Archaea clones indicated that all sediment depths associated with overlying orange- and white-pigmented microbial mats were almost exclusively dominated by ANME-2 (95% of total Archaea clones), a lineage related to the methanogenic order Methanosarcinales. In contrast, bacterial diversity was considerably higher, with the dominant phylotype varying by sediment depth. An equivalent number of clones detected at 0 to 2 cm, representing a total of 93%, were related to the γ and δ classes of Proteobacteria, whereas clones related to δ-Proteobacteria dominated the metabolically active fraction of the bacterial community occurring at 6 to 8 cm (79%) and 10 to 12 cm (85%). This is the first phylogenetics-based evaluation of the presumptive metabolically active fraction of the Bacteria and Archaea community structure investigated along a sediment depth profile in the northern Gulf of Mexico, a hydrocarbon-rich cold-seep region. PMID:15345432

  2. Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench.

    PubMed

    Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G

    2012-01-01

    The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples.

  3. Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench

    PubMed Central

    Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G.

    2012-01-01

    The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples. PMID:22822404

  4. Lipid biomarkers for anaerobic oxidation of methane and sulphate reduction in cold seep sediments of Nyegga pockmarks (Norwegian margin): discrepancies in contents and carbon isotope signatures

    NASA Astrophysics Data System (ADS)

    Chevalier, Nicolas; Bouloubassi, Ioanna; Stadnitskaia, Alina; Taphanel, Marie-Hélène; Sinninghe Damsté, Jaap S.

    2014-06-01

    Distributions and carbon isotopic compositions of microbial lipid biomarkers were investigated in sediment cores from the G11 and G12 pockmarks in the Nyegga sector of the Storegga Slide on the mid-Norwegian margin to explore differences in depth zonation, type and carbon assimilation mode of anaerobic methane-oxidizing archaea (ANMEs) and associated sulphate-reducing bacteria responsible for anaerobic oxidation of methane (AOM) in these cold seep environments. While the G11 site is characterised by black reduced sediments colonized by gastropods and Siboglinidae tubeworms, the G12 site has black reduced sediments devoid of fauna but surrounded by a peripheral occurrence of gastropods and white filamentous microbial mats. At both sites, bulk sediments contained abundant archaeal and bacterial lipid biomarkers substantially depleted in 13C, consisting mainly of isoprenoidal hydrocarbons and dialkyl glycerol diethers, fatty acids and non-isoprenoidal monoalkylglycerol ethers. At the G11 site, down-core profiles revealed that lipid biomarkers were in maximum abundance from 10 cm depth to the core bottom at 16 cm depth, associated with δ13C values of -57 to -136‰. At the G12 site, by contrast, lipid biomarkers were in high abundance in the upper 5 cm sediment layer, associated with δ13C values of -43 to -133‰. This suggests that, as expected from the benthic fauna characteristics of the sites, AOM takes place mainly at depth in the G11 pockmark but just below the seafloor in the G12 pockmark. These patterns can be explained largely by variable fluid flow rates. Furthermore, at both sites, a dominance of ANME-2 archaea accompanied by their bacterial partners is inferred based on lipid biomarker distributions and carbon isotope signatures, which is in agreement with recently published DNA analyses for the G11 pockmark. However, the present data reveal high discrepancies in the contents and δ13C values for both archaeal and bacterial lipid profiles, implying the

  5. Molecular characterization of TEM-type beta-lactamases identified in cold-seep sediments of Edison Seamount (south of Lihir Island, Papua New Guinea).

    PubMed

    Song, Jae Seok; Jeon, Jeong Ho; Lee, Jung Hun; Jeong, Seok Hoon; Jeong, Byeong Chul; Kim, Sang-Jin; Lee, Jung-Hyun; Lee, Sang Hee

    2005-04-01

    To determine the prevalence and genotypes of beta-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced beta-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five (16.7%) of thirty clones produced an extended-spectrum beta-lactamase. 837- and 259-bp fragments specific to blaTEM genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM-1 was the most prevalent beta-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type beta-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type beta-lactamases of the pre-antibiotic era indicates that TEM-type beta-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.

  6. Gas hydrate decomposition and migration of the sulfate/methane transition zone recorded by authigenic barite in cold seep sediments

    NASA Astrophysics Data System (ADS)

    Kasten, S.; Hensen, C.; Spiess, V.; Blumenberg, M.; Schneider, R. R.

    2010-12-01

    After deposition of sediments a whole suite of geochemical/biogeochemical and transport processes - subsumed under the term early diagenesis - can potentially alter the primary sediment composition. Post-depositional overprint is not only restricted to the topmost part of the sediment but well extends into more deeply buried sediments. A biogeochemical reaction front which is of particular importance for deep post-depositional alteration is the so-called sulfate/methane transition zone (SMTZ) where the anaerobic oxidation of methane (AOM) by sulfate occurs. This front is often located several meters to several tens of meters within the sediment and can heavily impact a number of sedimentary components and attributes - like carbonates, barite, iron oxide and iron sulfide minerals as well as rock magnetic properties (e.g., magnetic susceptibility). In this way the primary sediment composition is distinctly altered several thousands to tens of thousands of years after deposition. Identifying and quantifying such diagenetic overprint is of the utmost importance to accurately interpret the sedimentary record. In marine environments affected by hydrocarbon seepage and/or the presence of gas hydrates the geochemical zonation is often significantly condensed and the sulfate/methane transition zone is typically located close to the sediment surface - in this way impacting the initial sediment composition at relatively shallow depth. While the process of AOM induces the destruction of several primary sediment components it also goes along with the diagenetic formation of secondary signals. One of these diagenetically formed compounds is authigenic barite which precipitates slightly above the SMTZ. We demonstrate that - following the approach of Dickens (2001) - authigenic barite can be a valuable geochemical proxy to trace the downward migration of the SMTZ over time as a result of the decomposition of gas hydrates and/or a decrease in the upward flux of hydrocarbons

  7. Globin's structure and function in vesicomyid bivalves from the Gulf of Guinea cold seeps as an adaptation to life in reduced sediments.

    PubMed

    Decker, C; Zorn, N; Potier, N; Leize-Wagner, E; Lallier, F H; Olu, K; Andersen, A C

    2014-01-01

    Vesicomyid bivalves form dense clam beds in both deep-sea cold seeps and hydrothermal vents. The species diversity within this family raises questions about niche separation and specific adaptations. To compare their abilities to withstand hypoxia, we have studied the structure and function of erythrocyte hemoglobin (Hb) and foot myoglobin (Mb) from two vesicomyid species, Christineconcha regab and Laubiericoncha chuni, collected from the Regab pockmark in the Gulf of Guinea at a depth of 3,000 m. Laubiericoncha chuni possesses three monomeric globins, G1 (15,361 Da), G2 (15,668 Da), and G3 (15,682 Da) in circulating erythrocytes (Hb), and also three globins, G1, G3, and G4 (14,786 Da) in foot muscle (Mb). Therefore, globins G2 and G4 appear to be specific for erythrocytes and muscle, respectively, but globins G1 and G3 are common. In contrast, C. regab lacks erythrocyte Hb completely and possesses only globin monomers G1' (14,941 Da), G2' (15,169 Da), and G3' (15,683 Da) in foot muscle. Thus, these two vesicomyid species, C. regab and L. chuni, show a remarkable diversity in globin expression when examined by electrospray ionization mass spectrometry. Oxygen-binding affinities reveal extremely high oxygen affinities (P50 < 1 Torr, from 5° to 15°C at pH 7.5), in particular L. chuni globins, which might be an advantage allowing L. chuni to dig deeply for sulfides and remain buried for long periods in reduced sediments.

  8. Respiration of bivalves from three different deep-sea areas: Cold seeps, hydrothermal vents and organic carbon-rich sediments

    NASA Astrophysics Data System (ADS)

    Khripounoff, A.; Caprais, J. C.; Decker, C.; Le Bruchec, J.; Noel, P.; Husson, B.

    2017-08-01

    We studied bivalves (vesicomyids and mytilids) inhabiting four different areas of high sulfide and methane production: (1) in the Gulf of Guinea, two pockmarks (650 m and 3150 m depth) and one site rich in organic sediments in the deepest zone (4950 m average depth), (2) at the Azores Triple Junction on the Mid-Atlantic Ridge, one hydrothermal site (Lucky Strike vent field, 1700 m depth). Two types of Calmar benthic chambers were deployed, either directly set into the sediment (standard Calmar chamber) or fitted with a tank to isolate organisms from the sediment (modified Calmar chamber), to assess gas and solute exchanges in relation to bivalve bed metabolism. Fluxes of oxygen, total carbon dioxide, ammonium and methane were measured. At the site with organic-rich sediments, oxygen consumption by clams measured in situ with the standard benthic chamber was variable (1.3-6.7 mmol m-2 h-1) as was total carbon dioxide production (1-9.6 mmol m-2 h-1). The observed gas and solute fluxes were attributed primarily to bivalve respiration (vesicomyids or mytilids), but microbial and geochemical processes in the sediment may be also responsible for some of variations in the deepest stations. The respiration rate of isolated vesicomyids (16.1-0.25.7 μmol g-1 dry weight h-1) was always lower than that of mytilids (33 μmol g-1 dry weight h-1). This difference was attributed to the presence of a commensal scaleworm in the mytilids. The respiratory coefficient (QR) ≥1 indicated high levels of anaerobic metabolism. The O:N index ranged from 5 to 25, confirming that vesicomyids and mytilids, living in symbiosis with bacteria, have a protein-based food diet.

  9. Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore Costa Rica

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Krause, S.; Linke, P.; Hensen, C.; Dale, A. W.; Nuzzo, M.; Treude, T.

    2014-11-01

    Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane reaching the seafloor at cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at Quepos Slide site; a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m-2 d-1, with only 1 to 2.5% of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed Sediment-F low-Through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within 150-170 days. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

  10. Hydrocarbon geochemistry of cold seeps in the Monterey Bay National Marine Sanctuary

    USGS Publications Warehouse

    Lorenson, T.D.; Kvenvolden, K.A.; Hostettler, F.D.; Rosenbauer, R.J.; Orange, D.L.; Martin, J.B.

    2002-01-01

    Samples from four geographically and tectonically discrete cold seeps named Clam Flat, Clamfield, Horseshoe Scarp South, and Tubeworm City, within the Monterey Bay National Marine Sanctuary were analyzed for their hydrocarbon content. The sediment contains gaseous hydrocarbons and CO2, as well as high molecular weight aliphatic and aromatic hydrocarbons with various combinations of thermogenic and biogenic contributions from petroleum, marine, and terrigenous sources. Of particular interest is the cold seep site at Clamfield which is characterized by the presence of thermogenic hydrocarbons including oil that can likely be correlated with oil-saturated strata at Majors Creek near Davenport, CA, USA. At Clam Flat, the evidence for thermogenic hydrocarbons is equivocal. At Horseshoe Scarp South and Tubeworm City, hydrocarbon gases, mainly methane, are likely microbial in origin. These varied sources of hydrocarbon gases highlight the diverse chemical systems that appear at cold seep communities. ?? 2002 Elsevier Science B.V. All rights reserved.

  11. Infaunal and megafaunal benthic community structure associated with cold seeps at the Vestnesa Ridge (79 N°)

    NASA Astrophysics Data System (ADS)

    Åström, Emmelie K. L.; Carroll, Michael L.; Sen, Arunima; Ambrose, William G., Jr.; Silyakova, Anna; Carroll, JoLynn

    2016-04-01

    Cold seeps are locations where hydrocarbons, sulfide or reduced compounds emanate from the seafloor, which may fuel chemoautotrophic production and form additional hard bottom substrate through carbonate precipitation. Chemosynthetic symbiosis, trophic interactions, and additional bottom substrate types can provide a heterogeneous environment for deep-sea organisms supporting macrofaunal communities including increased biodiversity and biomass. We combined quantitative benthic faunal samples with sea floor photographs from an active, methane seeping pockmark at Vestnesa Ridge (1200 meters depth) to examine community structure and biodiversity in a high Arctic deep cold seep. Quantitative data were compared with samples from the nearby inactive Svyatogor Ridge (1577-1706 meters depth). We measured highly elevated methane concentrations (up to 100x background levels) in the sediment at Vestnesa Ridge. Faunal abundance, species richness and biomass were significantly higher at the Vestnesa pockmark compared to inactive Svyatogor Ridge. Seabed photos from Vestnesa Ridge reveal high megafaunal diversity and biomass and cold seep features including carbonate crust and microbial mats. Our observations indicate that chemoautotrophic production enhances deep-sea biomass and diversity at Vestnesa Ridge. The focused methane emissions create a heterogeneous deep-sea habitat for chemo-associated organisms coexisting with heterotrophic conventional fauna in a high Arctic seep. Keywords: Arctic, benthic ecology, biodiversity, chemosynthesis, methane

  12. Brine induced low-Magnesium calcite formation at cold seeps

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Roberts, Harry; Joye, Samantha; Heydari, Ezat

    2013-04-01

    Low-Mg calcite (LMC; < 5 mol% Mg), commonly observed during time intervals of "calcite seas," since the beginning of the Paleozoic Era, is a good indicator of low Mg/Ca ratio (< 2) in seawater. Calcite seas were coincident with times of active seawater-basalt interactions along mid-ocean ridges at high temperatures, which extract Mg from seawater and release Ca to it. In the modern aragonite sea, most carbonate minerals precipitate at the seafloor, including deposits from cold seep environments are primarily either aragonite or high-Mg calcite (HMC). Here, we report the finding of non-skeletal LMC from cold seeps in Alaminos Canyon block 601 (AC 601), 2200 m below the sea surface on northern Gulf of Mexico (GOM) continental slope. Low-Mg calcite usually represents the only carbonate mineral in the studied samples. Dominant allochems in these seep carbonates are peloids, grain aggregates, pelagic forams, and fragments of mollusks and echinoids. The limestone is heavily cemented. The observed cements include micrite, microspar, mosaic, bladed, fan, and needle cements. The dissolution of grains and cements was observed. Not only originally aragonitic mollusks shells, but also carbonate cement have been dissolved. The aerobic oxidation of reduced chemical species such as methane and H2S is responsible for an increase in pCO2 and a decrease of pH, leading to local carbonate dissolution. The occurrence of oxic conditions is confirmed by the presence of negative Ce anomalies of the carbonates. Further, we report on analyses showing that the ambient porewater Mg/Ca ratio actually governs the carbonate mineralogy. The occurrence of LMC may be attributed to the brine fluids, which is relatively Mg-depleted (Mg/Ca mole ratio is below 0.7) compared to pore fluid of the subsurface sediments from the reference site (Mg/Ca mole ratio is above 4.1) that usually produce HMC. The 87Sr/86Sr values of LMC (mean = 0.708001, sd = 0.000034, n=2) are significantly lower than that of the

  13. Diversity and distribution of methanotrophic archaea at cold seeps.

    PubMed

    Knittel, Katrin; Lösekann, Tina; Boetius, Antje; Kort, Renate; Amann, Rudolf

    2005-01-01

    In this study we investigated by using 16S rRNA-based methods the distribution and biomass of archaea in samples from (i) sediments above outcropping methane hydrate at Hydrate Ridge (Cascadia margin off Oregon) and (ii) massive microbial mats enclosing carbonate reefs (Crimea area, Black Sea). The archaeal diversity was low in both locations; there were only four (Hydrate Ridge) and five (Black Sea) different phylogenetic clusters of sequences, most of which belonged to the methanotrophic archaea (ANME). ANME group 2 (ANME-2) sequences were the most abundant and diverse sequences at Hydrate Ridge, whereas ANME-1 sequences dominated the Black Sea mats. Other seep-specific sequences belonged to the newly defined group ANME-3 (related to Methanococcoides spp.) and to the Crenarchaeota of marine benthic group B. Quantitative analysis of the samples by fluorescence in situ hybridization (FISH) showed that ANME-1 and ANME-2 co-occurred at the cold seep sites investigated. At Hydrate Ridge the surface sediments were dominated by aggregates consisting of ANME-2 and members of the Desulfosarcina-Desulfococcus branch (DSS) (ANME-2/DSS aggregates), which accounted for >90% of the total cell biomass. The numbers of ANME-1 cells increased strongly with depth; these cells accounted 1% of all single cells at the surface and more than 30% of all single cells (5% of the total cells) in 7- to 10-cm sediment horizons that were directly above layers of gas hydrate. In the Black Sea microbial mats ANME-1 accounted for about 50% of all cells. ANME-2/DSS aggregates occurred in microenvironments within the mat but accounted for only 1% of the total cells. FISH probes for the ANME-2a and ANME-2c subclusters were designed based on a comparative 16S rRNA analysis. In Hydrate Ridge sediments ANME-2a/DSS and ANME-2c/DSS aggregates differed significantly in morphology and abundance. The relative abundance values for these subgroups were remarkably different at Beggiatoa sites (80% ANME-2a, 20

  14. Co-Occurrence of Nitrate Reduction and Anaerobic Oxidation of Methane in Gulf of Mexico Cold Seep Habitats

    NASA Astrophysics Data System (ADS)

    Fields, L.; Joye, S. B.

    2014-12-01

    Cold seeps are abundant in the Gulf of Mexico; they are fuelled by methane gas and hydrocarbon seepage at the seafloor and support diverse chemosynthetic microbial communities. Microorganisms form the base of the food chain at cold seeps, and high rates of anaerobic oxidation of methane (AOM) are characteristic of these methane-rich environments. While sulfate is often the electron acceptor for AOM in cold seep environments, recent evidence suggests that AOM can also be coupled to nitrate reduction. Little is known about nitrogen cycling in these habitats, though recent work indicates that denitrification is an important process in oily and gassy seep sediments. The co-occurrence of nitrate reduction and AOM suggests a potential coupling between the two processes in our study area. We used stable isotope (15N) tracer techniques to measure the capacity of Northern Gulf of Mexico cold seep sediments to reduce nitrate by denitrification and anammox. These measurements were made in surface and sub-surface sediments in conjunction with measurements of AOM, and with quantification of various geochemical and molecular characteristics. Here, we present our measurements of denitrification and anammox capacity in the context of environmental characteristics. Additionally, we examine spatial trends in the co-occurrence of AOM and nitrate reduction in these sediments.

  15. Sidescan backscatter variations of cold seeps on the Hikurangi Margin (New Zealand): indications for different stages in seep development

    NASA Astrophysics Data System (ADS)

    Dumke, Ines; Klaucke, Ingo; Berndt, Christian; Bialas, Jörg

    2014-06-01

    Cold seeps on the Hikurangi Margin off New Zealand exhibit various seabed morphologies producing different intensity patterns in sidescan backscatter images. Acoustic backscatter characteristics of 25 investigated seep sites fall into four distinct types characterised by variations in backscatter intensity, distribution and inferred structural heights. The types reflect different carbonate morphologies including up to 20-m-high structures (type 1), low-relief crusts (type 2), scattered blocks (type 3) and carbonate-free sites (type 4). Each seep corresponds to a single type; intermediates were not observed. This correlates well with published data on seep fauna at each site, with the four types representing three different faunal habitats of successive stages of seep development. Backscatter signatures in sidescan sonar images of cold seeps may therefore serve as a convenient proxy for variations in faunal habitats.

  16. Macro-ecology of Gulf of Mexico cold seeps.

    PubMed

    Cordes, Erik E; Bergquist, Derk C; Fisher, Charles R

    2009-01-01

    Shortly after the discovery of chemosynthetic ecosystems at deep-sea hydrothermal vents, similar ecosystems were found at cold seeps in the Gulf of Mexico. Over the past two decades, these sites have become model systems for understanding the physiology of the symbiont-containing megafauna and the ecology of seep communities worldwide. Symbiont-containing bi-valves and siboglinid polychaetes dominate the communities, including five bathymodiolin mussel species and six vestimentiferan (siboglinid polychaete) species in the Gulf of Mexico. The mussels include the first described examples of methanotrophic symbiosis and dual methanotrophic/thiotrophic symbiosis. Studies with the vestimentiferans have demonstrated their potential for extreme longevity and their ability to use posterior structures for subsurface exchange of dissolved metabolites. Ecological investigations have demonstrated that the vestimentiferans function as ecosystem engineers and identified a community succession sequence from a specialized high-biomass endemic community to a low-biomass community of background fauna over the life of a hydrocarbon seep site.

  17. Spatial variations of bacterial communities and related biogeochemical activity of cold seep sites in the Eastern Mediterranean deep sea

    NASA Astrophysics Data System (ADS)

    Pop Ristova, P.; Felden, J.; Wenzhöfer, F.; Ramette, A.; Boetius, A.

    2012-04-01

    Cold seeps ecosystems, characterized by emissions of the potential greenhouse gas methane, and often associated with vast repositories of gas hydrates, represent patchy and isolated deep-sea oases of life. They host highly dynamic habitats that are spatially fragmented and temporarily variable. Microorganisms mediate all major geochemical processes at cold seeps i.e. anaerobic oxidation of methane and sulphide oxidation, which in turn enables high biomasses and biodiversity of chemosynthetic organisms to be sustained. Cold seeps are also characterized by high habitat heterogeneity and by dynamic geological, geochemical and biogenic processes influencing seep biodiversity. The deep Eastern Mediterranean sea, encompassing numerous geologically different cold seep sites, offers a unique opportunity for the study of habitat heterogeneity and effects on microbial communities at various spatial scales in relation to their biogeochemical environment. A combined approach, using molecular (ARISA and 454 pyrosequencing) and geochemical techniques (porewater analysis, ex situ radiotracer incubations and in situ quantifications of methane, oxygen and sulphide fluxes), was applied to investigate the biogeochemical activity and related bacterial diversity of hydrate-bearing seep-habitats. Here we present data on the comparison on large (> 100 km) and small (0.01 - 100 m) spatial scales, i.e. between and within different cold seep ecosystems, such as the Amon mud volcano, the Amsterdam mud volcano and the Central Pockmark area. Methane effluxes, sediment AOM rates and total oxygen uptake differed by an order of magnitude among habitats within a single cold seep structure, indicating high sediment heterogeneity on small (100 m) spatial scales. Conversely, similar geochemical conditions prevailed at seep-habitats separated by hundreds of kilometers. The bacterial community structures followed similar patterns, and highest variations could be detected at cold seeps with contrasting

  18. Formation of modern and Paleozoic stratiform barite at cold methane seeps on continental margins

    USGS Publications Warehouse

    Torres, M.E.; Bohrmann, G.; Dube, T.E.; Poole, F.G.

    2003-01-01

    Stratiform (bedded) Paleozoic barite occurs as large conformable beds within organic- and chert-rich sediments; the beds lack major sulfide minerals and are the largest and most economically significant barite deposits in the geologic record. Existing models for the origin of bedded barite fail to explain all their characteristics: the deposits display properties consistent with an exhalative origin involving fluid ascent to the seafloor, but they lack appreciable polymetallic sulfide minerals and the corresponding strontium isotopic composition to support a hydrothermal vent source. A new mechanism of barite formation, along structurally controlled sites of cold fluid seepage in continental margins, involves barite remobilization in organic-rich, highly reducing sediments, transport of barium-rich fluids, and barite precipitation at cold methane seeps. The lithologic and depositional framework of Paleozoic and cold seep barite, as well as morphological, textural, and chemical characteristics of the deposits, and associations with chemosymbiotic fauna, all support a cold seep origin for stratiform Paleozoic barite. This understanding is highly relevant to paleoceanographic and paleotectonic studies, as well as to economic geology.

  19. Microbial community changes along the active seepage site of one cold seep in the Red Sea.

    PubMed

    Cao, Huiluo; Zhang, Weipeng; Wang, Yong; Qian, Pei-Yuan

    2015-01-01

    The active seepage of the marine cold seeps could be a critical process for the exchange of energy between the submerged geosphere and the sea floor environment through organic-rich fluids, potentially even affecting surrounding microbial habitats. However, few studies have investigated the associated microbial community changes. In the present study, 16S rRNA genes were pyrosequenced to decipher changes in the microbial communities from the Thuwal seepage point in the Red Sea to nearby marine sediments in the brine pool, normal marine sediments and water, and benthic microbial mats. An unexpected number of reads from unclassified groups were detected in these habitats; however, the ecological functions of these groups remain unresolved. Furthermore, ammonia-oxidizing archaeal community structures were investigated using the ammonia monooxygenase subunit A (amoA) gene. Analysis of amoA showed that planktonic marine habitats, including seeps and marine water, hosted archaeal ammonia oxidizers that differed from those in microbial mats and marine sediments, suggesting modifications of the ammonia oxidizing archaeal (AOA) communities along the environmental gradient from active seepage sites to peripheral areas. Changes in the microbial community structure of AOA in different habitats (water vs. sediment) potentially correlated with changes in salinity and oxygen concentrations. Overall, the present results revealed for the first time unanticipated novel microbial groups and changes in the ammonia-oxidizing archaea in response to environmental gradients near the active seepages of a cold seep.

  20. Microbial community changes along the active seepage site of one cold seep in the Red Sea

    PubMed Central

    Cao, Huiluo; Zhang, Weipeng; Wang, Yong; Qian, Pei-Yuan

    2015-01-01

    The active seepage of the marine cold seeps could be a critical process for the exchange of energy between the submerged geosphere and the sea floor environment through organic-rich fluids, potentially even affecting surrounding microbial habitats. However, few studies have investigated the associated microbial community changes. In the present study, 16S rRNA genes were pyrosequenced to decipher changes in the microbial communities from the Thuwal seepage point in the Red Sea to nearby marine sediments in the brine pool, normal marine sediments and water, and benthic microbial mats. An unexpected number of reads from unclassified groups were detected in these habitats; however, the ecological functions of these groups remain unresolved. Furthermore, ammonia-oxidizing archaeal community structures were investigated using the ammonia monooxygenase subunit A (amoA) gene. Analysis of amoA showed that planktonic marine habitats, including seeps and marine water, hosted archaeal ammonia oxidizers that differed from those in microbial mats and marine sediments, suggesting modifications of the ammonia oxidizing archaeal (AOA) communities along the environmental gradient from active seepage sites to peripheral areas. Changes in the microbial community structure of AOA in different habitats (water vs. sediment) potentially correlated with changes in salinity and oxygen concentrations. Overall, the present results revealed for the first time unanticipated novel microbial groups and changes in the ammonia-oxidizing archaea in response to environmental gradients near the active seepages of a cold seep. PMID:26284035

  1. Mapping cold seeps with high-resolution deep water multibeam echosounders in the Black Sea

    NASA Astrophysics Data System (ADS)

    Wintersteller, P.; dos Santos Ferreira, C.; Klaucke, I.; Ivanov, M.; Sahling, H.; Bohrmann, G.

    2011-12-01

    Cold seeps are locations at the seafloor where gas and/or fluids are emitting. In contrast to mud volcanoes, which distinctly change the seafloor morphology, cold seeps often lack significant relief. However, in comparison with surrounding sediments seep locations on the sea floor are often characterized by high acoustic backscatter intensity. This was documented during several investigations with deep towed side-scan sonar (SSS) systems in recent years. Authigenic carbonates, free gas and gas hydrates, as evidenced by ground truthing, are responsible for the high backscatter values. Last year's upgrade of the 1°x2° KONGSBERG deep water echosounder EM120 to EM122 on RV Meteor enhanced the system to almost 4 times the previous resolution due to multi-ping and high density signal processing. Based on the physics of sound propagation in the water column, multibeam echosounders (MBES) for deep water use relatively low frequencies of about 12-15 kHz. Apparently highly water-saturated sediments are penetrated by these signals and can cause artificial offsets in bottom detection in comparison to high-frequency echosounders. Nevertheless the effect of the slightly penetrating signal has a useful side effect on the backscatter. Investigations on several seep sites in the Black Sea, carried out with both EM122 and EM710 during Meteror cruise M84-2, resulted in maps of remarkable bathymetric resolution but also showed multibeam backscatter information of a 12 kHz signal to be an excellent tool to map seep-influenced seafloor areas. New seep locations have been mapped in regions of the western Turkish continental margin close to Eregli and of the eastern Turkish margin off Samsun. In both areas high backscatter patches were mapped with nearly comparable resolution as achieved by deep-tow SSS systems. At Eregli the new data is compared with data from a deep-towed EdgeTech SSS system recorded with a frequency of 75 kHz. At Samsun the results are compared with data from a MAK-1

  2. Cold seep-related occurrence of the Early Jurassic rhynchonellid brachiopod Anarhynchia from the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Pálfy, József; Price, Gregory D.; Vörös, Attila; Kovács, Zsófia; Johannson, Gary G.

    2017-04-01

    Cold seeps, where seepage of methane and/or other hydrocarbon-rich fluids and hydrogen-sulfide occurs in the sea floor, are sites which harbor highly specialized ecosystems associated with distinctive carbonate sediments. Although their Mesozoic record is scarce and patchy, it commonly includes rhynchonellid brachiopods, often of large size. Each new occurrence is valuable in filling gaps and providing additional insight into these peculiar ecosystems. Here we report a monospecific assemblage of Anarhynchia from a boulder-sized limestone clast of Early Pliensbachian (Early Jurassic) age in the Inklin Formation of the Whitehorse Trough in Stikine terrane, recovered from a locality at Copper Island in Atlin Lake, northern British Columbia, Canada. Specimens are of unusually large size, up to 9 cm in length, and their external and internal morphology allows assignment to Anarhynchia but warrants introduction of a new species. Although d13C and d18O values of the shells are close to equilibrium with ancient seawater, early precipitated carbonate cement phases of the enclosing limestone are characterised by highly depleted carbon isotopic composition, indicative of the influence of microbial oxidation of methane derived from a cold seep. Carbonate petrography of the isopachous, banded-fibrous cement supports its origin in a cold seep environment. Volcanogenic detrital grains in the micritic matrix of the limestone clast are indistinguishable from those in the sandstone layers in the siliciclastic sequence, suggesting that the seep carbonate is broadly coeval with the enclosing conglomerate. Previously, Anarhynchia has been known from the Lower Jurassic of California and Oregon, from both cold seep and hydrothermal vent deposits. Our new record extends the geographic range and species-level diversity of the genus, but supports its endemism to the East Pacific and membership in chemosynthesis-based ecosystems.

  3. Anaerobic methane oxidation in low-organic content methane seep sediments

    USGS Publications Warehouse

    Pohlman, John W.; Riedel, Michael; Bauer, James E.; Canuel, Elizabeth A.; Paull, Charles K.; Lapham, Laura; Grabowski, Kenneth S.; Coffin, Richard B.; Spence, George D.

    2013-01-01

    Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sediment contains 14C. A fossil origin for the DIC precludes remineralization of non-fossil OM present within the sulfate zone as a significant contributor to pore water DIC, suggesting that nearly all sulfate is available for anaerobic oxidation of fossil seep methane. Methane flux from the SMT to the sediment water interface in a diffusion-dominated flux region of Bullseye vent was, on average, 96% less than at an OM-rich seep in the Gulf of Mexico with a similar methane flux regime. Evidence for enhanced methane oxidation capacity within OM-poor sediments has implications for assessing how climate-sensitive reservoirs of sedimentary methane (e.g., gas hydrate) will respond to ocean warming, particularly along glacially-influenced mid and high latitude continental margins.

  4. Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Krause, S.; Linke, P.; Hensen, C.; Dale, A. W.; Nuzzo, M.; Treude, T.

    2015-11-01

    Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m-2 d-1, with only 1 to 2.5 % of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

  5. Barite encrustation of benthic sulfur-oxidizing bacteria at a marine cold seep.

    PubMed

    Stevens, E W N; Bailey, J V; Flood, B E; Jones, D S; Gilhooly, W P; Joye, S B; Teske, A; Mason, O U

    2015-11-01

    Crusts and chimneys composed of authigenic barite are found at methane seeps and hydrothermal vents that expel fluids rich in barium. Microbial processes have not previously been associated with barite precipitation in marine cold seep settings. Here, we report on the precipitation of barite on filaments of sulfide-oxidizing bacteria at a brine seep in the Gulf of Mexico. Barite-mineralized bacterial filaments in the interiors of authigenic barite crusts resemble filamentous sulfide-oxidizing bacteria of the genus Beggiatoa. Clone library and iTag amplicon sequencing of the 16S rRNA gene show that the barite crusts that host these filaments also preserve DNA of Candidatus Maribeggiatoa, as well as sulfate-reducing bacteria. Isotopic analyses show that the sulfur and oxygen isotope compositions of barite have lower δ(34)S and δ(18)O values than many other marine barite crusts, which is consistent with barite precipitation in an environment in which sulfide oxidation was occurring. Laboratory experiments employing isolates of sulfide-oxidizing bacteria from Gulf of Mexico seep sediments showed that under low sulfate conditions, such as those encountered in brine fluids, sulfate generated by sulfide-oxidizing bacteria fosters rapid barite precipitation localized on cell biomass, leading to the encrustation of bacteria in a manner reminiscent of our observations of barite-mineralized Beggiatoa in the Gulf of Mexico. The precipitation of barite directly on filaments of sulfide-oxidizing bacteria, and not on other benthic substrates, suggests that sulfide oxidation plays a role in barite formation at certain marine brine seeps where sulfide is oxidized to sulfate in contact with barium-rich fluids, either prior to, or during, the mixing of those fluids with sulfate-containing seawater in the vicinity of the sediment/water interface. As with many other geochemical interfaces that foster mineral precipitation, both biological and abiological processes likely contribute

  6. Population genetic structure in Sabatieria (Nematoda) reveals intermediary gene flow and admixture between distant cold seeps from the Mediterranean Sea.

    PubMed

    De Groote, Annelies; Hauquier, Freija; Vanreusel, Ann; Derycke, Sofie

    2017-07-01

    There is a general lack of information on the dispersal and genetic structuring for populations of small-sized deep-water taxa, including free-living nematodes which inhabit and dominate the seafloor sediments. This is also true for unique and scattered deep-sea habitats such as cold seeps. Given the limited dispersal capacity of marine nematodes, genetic differentiation between such geographically isolated habitat patches is expected to be high. Against this background, we examined genetic variation in both mitochondrial (COI) and nuclear (18S and 28S ribosomal) DNA markers of 333 individuals of the genus Sabatieria, abundantly present in reduced cold-seep sediments. Samples originated from four Eastern Mediterranean cold seeps, separated by hundreds of kilometers, and one seep in the Southeast Atlantic. Individuals from the Mediterranean and Atlantic were divided into two separate but closely-related species clades. Within the Eastern Mediterranean, all specimens belonged to a single species, but with a strong population genetic structure (ΦST = 0.149). The haplotype network of COI contained 19 haplotypes with the most abundant haplotype (52% of the specimens) shared between all four seeps. The number of private haplotypes was high (15), but the number of mutations between haplotypes was low (1-8). These results indicate intermediary gene flow among the Mediterranean Sabatieria populations with no evidence of long-term barriers to gene flow. The presence of shared haplotypes and multiple admixture events indicate that Sabatieria populations from disjunct cold seeps are not completely isolated, with gene flow most likely facilitated through water current transportation of individuals and/or eggs. Genetic structure and molecular diversity indices are comparable to those of epiphytic shallow-water marine nematodes, while no evidence of sympatric cryptic species was found for the cold-seep Sabatieria.

  7. Sulfur biogeochemistry of cold seeps in the Green Canyon region of the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Formolo, Michael J.; Lyons, Timothy W.

    2013-10-01

    Cold seeps in the Gulf of Mexico provide a natural laboratory to study biogeochemical cycling of sulfur, carbon, and oxygen at hydrate- and hydrocarbon-rich deep marine settings with obvious additional relevance to studies of diverse modern and ancient seeps. Of particular interest are the sulfur isotope signatures of microbial sulfate reduction coupled to anaerobic oxidation of methane and other non-methane liquid and gaseous hydrocarbons. Whereas most of the published sulfur isotope data from cold seep systems pertain to pore-water species, our study integrates both solid and dissolved sulfur: acid-volatile sulfides (SAVS), pyrite (Spy), elemental sulfur (S°), dissolved sulfate and ΣH2S. Modeled and 35SO42- reduction rates and δ13C and δ18O data for authigenic carbonates are integrated within this sulfur framework. Our results indicate extreme variability over narrow spatial and temporal scales within short distances (meters) from active seeps. High rates of microbial sulfate reduction can lead to complete consumption of the sulfate within the upper few centimeters of burial, while meters away the sulfate profile shows little depletion. Such small-scale variability must reflect the structure and temporal dynamics of hydrocarbon migration in the presence of low amounts of background organic matter. Our past work demonstrated that electron donors other than methane drive significant levels of microbial activity at these seeps, and very recent work has demonstrated that oxidation of higher chain volatile hydrocarbons can contribute to the high levels of microbial activity. These findings are consistent with our new results. Elevated concentrations of pyrite and diagenetic carbonate relative to background sediments are diagnostic of active seepage, yet the S isotopes tell more complex stories. Low levels of the transient, 'instantaneous' products of S cycling-AVS and S°-show high δ34S values that increase with depth. Most of the pyrite formation, however, seems

  8. An overview of the latest results of cold seep research along the Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Greinert, J.; Faure, K.; Bialas, J.; Linke, P.; Pecher, I.; Rowden, A.

    2008-12-01

    Prior to 2006, the knowledge about cold seeps around New Zealand was based mainly on accidental recovery of seep fauna or methane-derived carbonates by fishermen and flares in echo sounders. Lewis and Marshall (1996) compiled these findings, providing the first details on 13 seep sites. Four of those are located at the Hikurangi Margin along the east coast of New Zealand's North Island. Since then, three international cruises in 2006 and 2007 enhanced our knowledge considerably about methane seepage along the Hikurangi Margin, an area which has in places very strong BSRs. Two cruises on RV TANGAROA in 2006 focused on extensive reconnaissance work as well as fauna sampling, geochemical pore water analyses and CTD casts including water sampling for methane analyses. Several new seep sites were discovered during these cruises. Using these data, very detailed investigations in four main working areas could be performed during a 10-weeks expedition with RV SONNE (SO191). All research topics currently discussed in the scientific community were addressed using state-of-the-art equipment (e.g. deep- tow side-scan and ROV-deployments). Fourteen institutes from seven countries were involved. Echosounder and sidescan surveys unmistakably revealed active seep sites by detecting bubbles in the water column and carbonate precipitation at the seafloor forming massive chemoherm complexes. These complexes are associated with typical seep fauna like tube worms, bivalve mollusk species (Calyptogena, Bathymodiolus),and bacterial mats. At the fringe of these chemoherms dark sediment patches were observed which exihibit a novel seep habitat dominated by dense beds of two new species of heterotrophic ampharetid polychaetes. Bubble release was visually observed at several sites and recorded in the backscatter of various acoustic devices. At one site (680m water depth) very strong, pulsing outbursts could be observed repeatedly with methane fluxes of 20 to 25 l/min (60 to 74 mol

  9. Metagenomics in methane seep detection and studies of the microbial methane sediment filter

    NASA Astrophysics Data System (ADS)

    Gunn Rike, Anne; Håvelsrud, Othilde Elise; Haverkamp, Thomas; Kristensen, Tom; Jakobsen, Kjetill

    2013-04-01

    and represent a carbon source for the autotrophic nitrifying community. In this way the sediments at Troll probably contributes to reduce the methane emissions to the water body and further to the atmosphere (3). References: 1) Niemann H, Lösekann T, Boetius A, Kort R, Amann R. Diversity and distribution of methanotrophic archaea at cold seeps. Appl Environ Microbiol 2005, 71(1), 467-479. 2) Håvelsrud, O. E., Haverkamp, T.H.A., Kristensen, T., Jakobsen, K.S. and Rike A.G. Metagenomic study of methane oxidation in Coal Oil Point seep sediments. BMC Microbiology 2011, 11:221 3) Håvelsrud OE, Haverkamp THA., Kristensen T, Jakobsen KS and Rike AG. Metagenomic and geochemical characterization of pockmarked sediments overlaying the Troll petroleum reservoir in the North Sea. BMC Microbiology 2012, 12:203

  10. Cold Seep Epifaunal Communities on the Hikurangi Margin, New Zealand: Composition, Succession, and Vulnerability to Human Activities

    PubMed Central

    Bowden, David A.; Rowden, Ashley A.; Thurber, Andrew R.; Baco, Amy R.; Levin, Lisa A.; Smith, Craig R.

    2013-01-01

    Cold seep communities with distinctive chemoautotrophic fauna occur where hydrocarbon-rich fluids escape from the seabed. We describe community composition, population densities, spatial extent, and within-region variability of epifaunal communities at methane-rich cold seep sites on the Hikurangi Margin, New Zealand. Using data from towed camera transects, we match observations to information about the probable life-history characteristics of the principal fauna to develop a hypothetical succession sequence for the Hikurangi seep communities, from the onset of fluid flux to senescence. New Zealand seep communities exhibit taxa characteristic of seeps in other regions, including predominance of large siboglinid tubeworms, vesicomyid clams, and bathymodiolin mussels. Some aspects appear to be novel; however, particularly the association of dense populations of ampharetid polychaetes with high-sulphide, high-methane flux, soft-sediment microhabitats. The common occurrence of these ampharetids suggests they play a role in conditioning sulphide-rich sediments at the sediment-water interface, thus facilitating settlement of clam and tubeworm taxa which dominate space during later successional stages. The seep sites are subject to disturbance from bottom trawling at present and potentially from gas hydrate extraction in future. The likely life-history characteristics of the dominant megafauna suggest that while ampharetids, clams, and mussels exploit ephemeral resources through rapid growth and reproduction, lamellibrachid tubeworm populations may persist potentially for centuries. The potential consequences of gas hydrate extraction cannot be fully assessed until extraction methods and target localities are defined but any long-term modification of fluid flow to seep sites would have consequences for all chemoautotrophic fauna. PMID:24204691

  11. Cold seep epifaunal communities on the Hikurangi margin, New Zealand: composition, succession, and vulnerability to human activities.

    PubMed

    Bowden, David A; Rowden, Ashley A; Thurber, Andrew R; Baco, Amy R; Levin, Lisa A; Smith, Craig R

    2013-01-01

    Cold seep communities with distinctive chemoautotrophic fauna occur where hydrocarbon-rich fluids escape from the seabed. We describe community composition, population densities, spatial extent, and within-region variability of epifaunal communities at methane-rich cold seep sites on the Hikurangi Margin, New Zealand. Using data from towed camera transects, we match observations to information about the probable life-history characteristics of the principal fauna to develop a hypothetical succession sequence for the Hikurangi seep communities, from the onset of fluid flux to senescence. New Zealand seep communities exhibit taxa characteristic of seeps in other regions, including predominance of large siboglinid tubeworms, vesicomyid clams, and bathymodiolin mussels. Some aspects appear to be novel; however, particularly the association of dense populations of ampharetid polychaetes with high-sulphide, high-methane flux, soft-sediment microhabitats. The common occurrence of these ampharetids suggests they play a role in conditioning sulphide-rich sediments at the sediment-water interface, thus facilitating settlement of clam and tubeworm taxa which dominate space during later successional stages. The seep sites are subject to disturbance from bottom trawling at present and potentially from gas hydrate extraction in future. The likely life-history characteristics of the dominant megafauna suggest that while ampharetids, clams, and mussels exploit ephemeral resources through rapid growth and reproduction, lamellibrachid tubeworm populations may persist potentially for centuries. The potential consequences of gas hydrate extraction cannot be fully assessed until extraction methods and target localities are defined but any long-term modification of fluid flow to seep sites would have consequences for all chemoautotrophic fauna.

  12. Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

    USGS Publications Warehouse

    Pohlman, J.W.; Bauer, J.E.; Canuel, E.A.; Grabowski, K.S.; Knies, D.L.; Mitchell, C.S.; Whiticar, Michael J.; Coffin, R.B.

    2009-01-01

    Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon (14C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ??13C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14C mass balance approach using fossil methane and 14C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

  13. Anaerobic methane oxidation in low-organic content methane seep sediments

    NASA Astrophysics Data System (ADS)

    Pohlman, John W.; Riedel, Michael; Bauer, James E.; Canuel, Elizabeth A.; Paull, Charles K.; Lapham, Laura; Grabowski, Kenneth S.; Coffin, Richard B.; Spence, George D.

    2013-05-01

    Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sediment contains <0.4 wt.% total organic carbon (OC) and primarily consists of glacially-derived material that was deposited 14,900-15,900 yrs BP during the retreat of the late Quaternary Cordilleran Ice Sheet. We hypothesize this aged and exceptionally low-OC content sedimentary OM is biologically refractory, thereby limiting degradation of non-methane OM by sulfate reduction and maximizing methane consumption by sulfate-dependent AOM. A radiocarbon-based dissolved inorganic carbon (DIC) isotope mass balance model demonstrates that respired DIC in sediment pore fluids is derived from a fossil carbon source that is devoid of 14C. A fossil origin for the DIC precludes remineralization of non-fossil OM present within the sulfate zone as a significant contributor to pore water DIC, suggesting that nearly all sulfate is available for anaerobic oxidation of fossil seep methane. Methane flux from the SMT to the sediment water interface in a diffusion-dominated flux region of Bullseye vent was, on average, 96% less than at an OM-rich seep in the Gulf of Mexico with a similar methane flux regime. Evidence for enhanced methane oxidation capacity within OM-poor sediments has implications for assessing how climate-sensitive reservoirs of sedimentary methane (e.g., gas hydrate) will respond to ocean warming, particularly along glacially-influenced mid and high latitude continental margins.

  14. Experimental determination of REE partition coefficients in cold seep carbonate phases

    NASA Astrophysics Data System (ADS)

    Rongemaille, Emmanuelle; Niedermayr, Andrea; Dietzel, Martin; Bollinger, Claire; Liebetrau, Volker; Pierre, Catherine; Bayon, Germain

    2010-05-01

    Experimental determination of REE partition coefficients in cold seep carbonate phases Authigenic carbonates are suitable archives for investigating past circulation events of methane-rich fluids on continental margins. Tracing fluid sources at cold seeps is important for better constraining the geological context in which they are expelled. Until recently, however, the origin of the fluids was mainly inferred using the stable isotopic composition of carbon and oxygen, which allowed discrimination between biogenic versus thermogenic source. The development of new proxies is needed to bring additional information on fluid sources on continental margins, and to better constrain changes in fluid composition through time. The rare earth elements (REEs) behave as a coherent group of elements, which have been used widely to provide information on mixing between water masses and biogeochemical processes in the ocean. Early diagenetic reactions in marine sediment (e.g. degradation of organic compounds, reduction of Fe and Mn oxyhydroxides) lead to strong enrichment of the REE contents in pore waters relative to seawater (up to 100 times). As a consequence, the application of REE geochemistry to cold seep carbonates is particularly well suited for investigating fluid sources in sediments from continental margins. In order to validate this new approach, and because the incorporation of the REE during carbonate precipitation may also be dependent on their mineralogy, it is important to determine the role played by mineralogy versus fluid chemistry in controlling the REE signature of cold seep carbonates. In this regard, the knowledge of partition coefficient for REE in the main carbonate phases encountered at cold seeps (aragonite, calcite and magnesian calcite) is crucial. In this study, we report REE partition coefficient for the carbonate phases typically found in cold seep environments (aragonite, calcite, magnesian calcite). The carbonate phases were precipitated by CO2

  15. Altererythrobacter epoxidivorans gen. nov., sp. nov., an epoxide hydrolase-active, mesophilic marine bacterium isolated from cold-seep sediment, and reclassification of Erythrobacter luteolus Yoon et al. 2005 as Altererythrobacter luteolus comb. nov.

    PubMed

    Kwon, Kae Kyoung; Woo, Jung-Hee; Yang, Sung-Hyun; Kang, Ji-Hyun; Kang, Sung Gyun; Kim, Sang-Jin; Sato, Takako; Kato, Chiaki

    2007-10-01

    A novel marine bacterium, strain JCS350(T), was isolated from marine sediment samples collected from a cold-seep area. The 16S rRNA gene sequence of the isolate showed high similarity to that of Erythrobacter luteolus SW-109(T) (95.9 % sequence similarity). Lower 16S rRNA gene sequence similarities were shown to other members of the genus Erythrobacter (94.6-95.4 %) and members of the genus Porphyrobacter (94.5-95.2 %). Phylogenetic analysis with all members of the family Erythrobacteraceae and several members of the family Sphingomonadaceae revealed that the isolate formed a phyletic line with [Erythrobacter] luteolus that was distinct from other members of the family Erythrobacteraceae. The dominant fatty acids of strain JCS350(T) were 18 : 1omega7c, 16 : 1omega7c and cyclopropane 17 : 0. The major respiratory quinone was ubiquinone 10. The DNA G+C content was 54.5 mol%. The isolate did not contain bacteriochlorophyll a. Optimal growth required the presence of 2 % (w/v) NaCl with either 0.18 % CaCl(2) or 0.59 % MgCl(2), at pH 6.5 and at 35 degrees C. On the basis of the evidence of this polyphasic taxonomic study, strain JCS350(T) should be classified in a novel genus and species in the family Erythrobacteraceae, for which the name Altererythrobacter epoxidivorans gen. nov., sp. nov. is proposed. The misclassified species [Erythrobacter] luteolus is transferred to the new genus as Altererythrobacter luteolus comb. nov. The type strain of Altererythrobacter epoxidivorans is JCS350(T) (=KCCM 42314(T) =JCM 13815(T)) and the type strain of Altererythrobacter luteolus is SW-109(T) (=KCTC 12311(T) =JCM 12599(T)).

  16. First biomarker evidence for methane oxidation at cold seeps in the Southeast Atlantic (REGAB pockmark)

    NASA Astrophysics Data System (ADS)

    Bouloubassi, Ioanna; Nabais, Elisabeth; Pancost, Richard D.; Lorre, Anne; Taphanel, Marie-Hélène

    2009-12-01

    Sediment cores from the REGAB pockmark, an active cold seep area in the southeast Atlantic, were analysed for their lipid biomarker distribution and associated stable carbon isotopic composition. Substantial amounts of diagnostic archaeal lipids were found, consisting mainly of archaeol, sn-2 hydroxyarchaeol and crocetane. All archaeal lipids were profoundly depleted in 13C with δ 13C values as low as -133‰. Concurrently, abundant monoalkylglycerolethers (MAGE), assigned to sulphate-reducing bacteria, were identified and showed strong 13C-depletions (δ 13C between -86‰ and -95‰). The structural and isotopic patterns of these microbial lipids provided compelling evidence for anaerobic oxidation of methane (AOM) occurring in REGAB sediments, mediated by archaea and sulphate reducing bacteria. Lipid fingerprints indicated that anaerobic methanotrophic archaea (ANME-2) and sulphate-reducing bacteria from the Desulfosarcina/Desulfococcus cluster are the dominant AOM assemblages. Depth profiles implied that highest AOM takes place below the upper 2 cm, mainly in the 6-12 cm depth interval. Significant abundances of 13C-depleted diploptene and 4α-methylsterols were found as well, inferring that aerobic methanotrophy occurs in the surface sediment interval. This first biomarker study at the recently investigated cold seeps in the SE Atlantic expand on existing work on AOM settings and add new evidence for aerobic and anaerobic methanotrophic communities occurring in close vicinity.

  17. More than three thousand years of microbial methane consumption at cold seeps offshore Svalbard

    NASA Astrophysics Data System (ADS)

    Steinle, Lea; Vögtli, Irina; Liebetrau, Volker; Krause, Stefan; Treude, Tina; Lehmann, Moritz; Niemann, Helge

    2014-05-01

    Microbial consumption retains a significant fraction of methane in marine sediments. Under anoxic conditions, the anaerobic oxidation of methane (AOM) is mediated by archaea with sulfate as the terminal electron acceptor, whereas the aerobic oxidation of methane (MOx) is mediated by bacteria. MOx is typically less important in marine systems because oxygen availability in sediments is very low and methane is consumed in deeper sediments through AOM. At cold seeps, however, the methane flux can be high enough to bypass the AOM filter so that methane and oxygen overlap in surface sediments. The role of MOx thus becomes more significant at highly active cold seeps. To further test this hypothesis, and the applicability of MOx-signatures as a tracer for paleo seep activity, we investigated lipid biomarkers of methanotrophic communities in modern sediments and compared them to fossilised lipids in more than 3000 years old authigenic carbonate accretions. Sediments and carbonates were recovered in the direct vicinity of bubble release sites at cold seeps offshore Svalbard, systems that have been active for at least 3000 years (Berndt et al., 2014). Samples were recovered with the submersible JAGO during an expedition with R/V M.S. Merian (MSM 21/4) in 2012. The composition of lipid biomarkers and their associated stable carbon isotope signatures provide evidence for distinctly different methanotrophic communities in modern sediments and the old carbonates. In deeper sediments, where AOM rate measurements were maximal (~500 nmol ml-1 d-1 at ~5 cm sediment depth), the dominance of the 13C-depleted archaeal biomarker archaeol and the absence of sn2-hydroxyarchaeol and crocetane point to an AOM community dominated by ANME1-archaea. At the surface of the sediment core, we found 13C-depleted 4α-methylsteroids and diploptene, lipid biomarkers originating from MOx communities. The biomarker profiles are consistent with our visual observations. During sampling, methane bubbles

  18. Geochemical zonation and characteristics of cold seeps along the Makran continental margin off Pakistan

    NASA Astrophysics Data System (ADS)

    Fischer, D.; Bohrmann, G.; Zabel, M.; Kasten, S.

    2009-04-01

    Several highly dynamic and spatially extended cold seeps were found and analyzed on the Makran accretionary wedge off Pakistan during R/V Meteor cruise M74-3 in 2007. In water depths of 550m to 2870m along the continental slope nine different gas escape structures were examined some of which are situated within a stable oxygen minimum zone (OMZ) between 150m and 1100m water depth (von Rad et al., 1996, 2000). Echosounder data indicate several gas bubble streams in the water column. The gas seepage presumably originates from squeezing of massive sediment packages being compressed by subduction at the continental margin off Pakistan. Gas- and fluid venting and associated surface-near anaerobic oxidation of methane (AOM) feed several cold seepage systems in the seabed. The seep sites show strong inter- and intraspecific variability of benthic chemosynthetic microhabitats. Singular seeps are often colonized by different chemosynthetic organisms in a concentric fashion. The seep-center, where active bubble ebullition occurs, is often colonized by large hydrogen sulfide-oxidizing bacteria, which are surrounded by a rim inhabited by small chemosynthetic clams and tube worms. These different habitats and the associated sediments show distinct geochemical zonations and gradients. Geochemical analyses of pore water and sediment samples obtained via ROV (push corer) show that concentrations of hydrogen sulfide and alkalinity rapidly increase to >15 mmol/l and >35 mmol/l respectively several cm below the seafloor in the center of the cold seep. In places, sulfate is depleted to concentrations below detection limit at the same depth (ROV push core GeoB 12313-6). Ammonium concentrations in this core on the other hand show a different pattern: In the center of the cold seep, which is colonized by bacterial assemblages, ammonium concentrations fluctuate around 100 µmol/l and peak with 274.4 µmol/l just above the aforementioned sulfide maximum values at 5 cm followed by a rapid

  19. Diversity and Characteristics of Benthic Foraminifera in Cold Seep Areas in the Active Margin of the northeastern South China Sea

    NASA Astrophysics Data System (ADS)

    Chiang, Meng-Ting; Thomas, Ellen; Wei, Kuo-Yen; Lin, Yu-Shih; Lin, Saulwood; Tien-Shun Lin, Andrew

    2015-04-01

    The active continental margin in northeastern South China Sea (SCS) has been considered to have high potential to be a reservoir of gas hydrate, based on geographic features, geophysical evidences, as well as geochemical analyses of samples from the water column, pore water and sediments. Compared to a typical sea floor area, cold seep areas have more food for benthos and more diverse habitats. As a result, we can expect a higher species diversity of benthic organisms in cold seep areas of the SCS. Based on preliminary results of species identification of benthic foraminiferal assemblages in the upper most sediments (0-5 cm) of box cores collected around cold seeps at water depth ~1300m, the species diversity is significantly higher at seep sites (Shannon-Wiener index = 274) than at background sites (Shannon-Wiener index = 3). The faunal assemblages consist of ~68% calcareous benthic foraminifera (CBF) and ~32% agglutinated benthic foraminifera (ABF) at seep sites. On the other hand, faunal assemblages are composed of only ~24% CBF and ~76% ABF at background sites. By staining the sample with rose Bengal-ethanol solution, we were able to recognize in-situ individuals which were alive at the time of collection, and separate them from dead specimens. Among the living individuals, the most abundant CBF species in seep sites is Bulimina aculeata (~51% in the living CBF fauna), followed by the typical 'shelf-species,' Lenticulina inornata, (~10%) and the common 'brackish-species,' Miliolinella subrotunda, (~9%), while the most abundant ABF species is Cribrostomoides subglobosus (~19% in the living ABF fauna). The most common species thus are typical for shallower, more food rich environments.

  20. Vertical distribution and diversity of bacteria and archaea in sulfide and methane-rich cold seep sediments located at the base of the Florida Escarpment.

    PubMed

    Reed, Andrew J; Lutz, Richard A; Vetriani, Costantino

    2006-06-01

    The bacterial and archaeal communities of the sediments at the base of the Florida Escarpment (Gulf of Mexico, USA) were investigated using molecular phylogenetic analysis. The total microbial community DNA of each of three vertical zones (top, middle and bottom) of a sediment core was extracted and the 16S rRNA genes were amplified by PCR, cloned and sequenced. Shannon-Weaver Diversity measures of bacteria were high in all three zones. For the archaea, diversity was generally low, but increased with depth. The archaeal clonal libraries were dominated by representatives of four groups of organisms involved in the anaerobic oxidation of methane (ANME groups). Phylogenetic analysis of bacteria suggests the dominance of epsilon-proteobacteria in the top zone, the epsilon-, delta- and gamma-proteobacteria in the middle zone and the delta-proteobacteria in the bottom zone of the core. Members of the Cytophaga-Flexibacter-Bacteroidetes group, the Chloroflexi/green non-sulfur bacteria, the Gram+ (Firmicutes), the Planctomyces, candidate division WS3 and Fusobacterium were also detected. Our data suggest that the community structure and diversity of microorganisms can shift greatly within small vertical distances, possibly in response to changes in the physical and chemical conditions.

  1. Sulfur isotope and porewater geochemistry of Florida escarpment seep sediments

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Paull, C.K.; Coston, J.A.

    1993-01-01

    Distributions of porewater constituents, SO4=, NH4+, Cl-, ???CO2, and H2S, solid phase iron, and sulfur concentrations, and the sulfur isotopic composition of dissolved and solid phases were investigated in sediments from abyssal seeps at the base of the Florida escarpment. Despite the apparent similarity of seep sediment porewater chemistry to that of typical marine sediments undergoing early diagenesis, relationships between chemical distributions and isotopic measurements revealed that the distribution of pore fluid constituents was dominated by processes occurring within the platform rather than by in situ microbial processes. Ammonium and sulfate concentrations were linearly correlated with chloride concentrations, indicating that variations in porewater chemistry were controlled by the admixture of seawater and a sulfate depleted brine with a chlorinity of 27.5 ?? 1.9%. and 2.2 ?? 1.3 mM ammonium concentration. At sites dominated by seepage, dissolved sulfate isotopic composition remained near seawater values despite depletion in porewater concentrations. Porewater ???CO2 concentrations were found to be elevated relative to seawater, but not to the extent predicted from the observed sulfate depletion. Sediment solid phase sulfur was predominantly pyrite, at concentrations as high as 20% S by weight. In contrast to typical marine deposits, pyrite concentrations were not related to the quantity of sedimentary organic matter. Pyrite ??34S values ranged from -29%. to + 21%. (CDT). However, only positive ??34S values were observed at sites associated with high pyrite concentrations. Isotopically heavy pyrite was observed at sites with porewater sulfate of seawater-like isotopic composition. Isotopically light pyrite was associated with sites where porewater sulfate exhibited ??34S values greater than those in seawater, indicating the activity of in situ microbial sulfate reduction. Thus, dual sulfide sources are suggested to explain the range in sediment pyrite

  2. Three-dimensional structure of fluid conduits sustaining an active deep marine cold seep

    USGS Publications Warehouse

    Hornbach, M.J.; Ruppel, C.; Van Dover, C.L.

    2007-01-01

    Cold seeps in deep marine settings emit fluids to the overlying ocean and are often associated with such seafloor flux indicators as chemosynthetic biota, pockmarks, and authigenic carbonate rocks. Despite evidence for spatiotemporal variability in the rate, locus, and composition of cold seep fluid emissions, the shallow subseafloor plumbing systems have never been clearly imaged in three dimensions. Using a novel, high-resolution approach, we produce the first three-dimensional image of possible fluid conduits beneath a cold seep at a study site within the Blake Ridge gas hydrate province. Complex, dendritic features diverge upward toward the seafloor from feeder conduits at depth and could potentially draw flow laterally by up to 103 m from the known seafloor seep, a pattern similar to that suggested for some hydrothermal vents. The biodiversity, community structure, and succession dynamics of chemosynthetic communities at cold seeps may largely reflect these complexities of subseafloor fluid flow.

  3. Cold-seep carbonates of the middle and lower continental slope, northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Roberts, Harry H.; Feng, Dong; Joye, Samantha B.

    2010-11-01

    Authigenic carbonates from cold seeps on the middle and lower continental slope of the northern Gulf of Mexico (GOM) exhibit a wide range of mineralogical and stable isotopic compositions. These carbonates consist of concretions and nodules in surface sediments, hardgrounds of crusts and isolated slabs, and mounded buildups of blocks and slabs of up to over 10 meters in relief above the surrounding seafloor. Mineralogically, the carbonates are dominated by high-Mg calcite (HMC) and aragonite. However, low levels (<5 wt%) of dolomite are present in most samples. Petrographically, Mg-calcite peloidal matrix and acicular to botryoidal aragonitic void-filling cements are the most frequent associations. The carbon isotopic compositions of the carbonates range from -60.8 to 14.0‰ PDB, indicating complex carbon sources that include 13C-depleted biogenic and thermogenic methane, biodegraded crude oil, seawater CO2, and 13C-enriched residual CO2 from methanogenesis. A similarly large variability in δ18O values (2.5 to 6.7‰ PDB) demonstrates the geochemical complexity of the slope, with some samples pointing toward an 18O-enriched oxygen source that is possibly related to advection of 18O-enriched formation water and/or to the decomposition of gas hydrate. A considerable range of mineralogical and isotopic variations in cold-seep carbonate composition was noted even within individual study sites. However, common trends occur across multiple geographic areas. This situation suggests that local controls on fluid and gas flux, types of seep hydrocarbons, the presence or absence of gas hydrate in the near-surface sediment, and chemosynthetic communities, as well as the temporal evolution of the local hydrocarbon reservoir, all may play a part in determining carbonate mineralogy and isotope geochemistry. The carbon isotope data clearly indicate that between-site variation is greater than within-site variation. Seep carbonates formed on the middle and lower continental slope

  4. Paleo-environmental controls on cold seep carbonate authigenesis in the Sea of Marmara

    NASA Astrophysics Data System (ADS)

    Crémière, Antoine; Bayon, Germain; Ponzevera, Emmanuel; Pierre, Catherine

    2013-08-01

    The factors controlling fluid emission dynamics at ocean margins are poorly understood. In particular, there are significant uncertainties on how fluid seepage at cold seeps may have responded to abrupt environmental changes in the geological past. This study reports on a detailed geochemical investigation of seafloor carbonate crusts sampled at cold seeps along the submerged part of the North Anatolian Fault system in the Sea of Marmara - an inland sea, which has experienced major paleo-environmental changes over the last deglaciation period. We also analyzed a series of authigenic carbonate concretions recovered from two sediment cores at the Western-High ridge, an active fluid venting area. The ages of seafloor carbonate crusts derived from isochron U-Th dating cover the last 7 kyr, suggesting that fluid activity along the fault system remained continuous over that time interval. In the sediment cores, carbonate concretions are concentrated at the lacustrine-to-marine transition, which corresponds to the period when Mediterranean waters flowed into the Marmara Basin about 12-14 kyr ago. U-Th isotopic data indicate that most of these concretions formed later during the Holocene, around 9-10 kyr ago, a period coinciding with an important anoxic event that led to the deposition of a sapropel layer in the Sea of Marmara. Based upon these results, we suggest that the absence of carbonate concretions in the lacustrine sediment unit indicates that dissolved sulfate concentrations in the Marmara lake pore waters during glacial time were too low to promote significant anaerobic methane oxidation, thereby preventing sedimentary carbonate authigenesis. In contrast, the progressive inflow of Mediterranean waters into the glacial Marmara lake after 15 ka provided a source of dissolved sulfate that allowed anaerobic oxidation of methane to proceed within the anoxic sediment. Importantly, the synchronism between the main phase of authigenic carbonate precipitation at the

  5. Cold seeps associated with a submarine debris avalanche deposit at Kick'em Jenny volcano, Grenada (Lesser Antilles)

    NASA Astrophysics Data System (ADS)

    Carey, Steven; Ballard, Robert; Bell, Katherine L. C.; Bell, Richard J.; Connally, Patrick; Dondin, Frederic; Fuller, Sarah; Gobin, Judith; Miloslavich, Patricia; Phillips, Brennan; Roman, Chris; Seibel, Brad; Siu, Nam; Smart, Clara

    2014-11-01

    Remotely operated vehicle (ROV) exploration at the distal margins of a debris avalanche deposit from Kick'em Jenny submarine volcano in Grenada has revealed areas of cold seeps with chemosynthetic-based ecosystems. The seeps occur on steep slopes of deformed, unconsolidated hemipelagic sediments in water depths between 1952 and 2042 m. Two main areas consist of anastomosing systems of fluid flow that have incised local sediments by several tens of centimeters. No temperature anomalies were observed in the vent areas and no active flow was visually observed, suggesting that the venting may be waning. An Eh sensor deployed on a miniature autonomous plume recorder (MAPR) recorded a positive signal and the presence of live organisms indicates at least some venting is still occurring. The chemosynthetic-based ecosystem included giant mussels (Bathymodiolus sp.) with commensal polychaetes (Branchipolynoe sp.) and cocculinid epibionts, other bivalves, Siboglinida (vestimentiferan) tubeworms, other polychaetes, and shrimp, as well as associated heterotrophs, including gastropods, anemones, crabs, fish, octopods, brittle stars, and holothurians. The origin of the seeps may be related to fluid overpressure generated during the collapse of an ancestral Kick'em Jenny volcano. We suggest that deformation and burial of hemipelagic sediment at the front and base of the advancing debris avalanche led to fluid venting at the distal margin. Such deformation may be a common feature of marine avalanches in a variety of geological environments especially along continental margins, raising the possibility of creating large numbers of ephemeral seep-based ecosystems.

  6. Methane Metabolizing Microbial Communities in the Cold Seep Areas in the Northern Continental Shelf of South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, F.; Liang, Q.

    2016-12-01

    Marine sediment contains large amount of methane, estimated approximately 500-2500 gigatonnes of dissolved and hydrated methane carbon stored therein, mainly in continental margins. In localized specific areas named cold seeps, hydrocarbon (mainly methane) containing fluids rise to the seafloor, and support oases of ecosystem composed of various microorganisms and faunal assemblages. South China Sea (SCS) is surrounded by passive continental margins in the west and north and convergent margins in the south and east. Thick organic-rich sediments have accumulated in the SCS since the late Mesozoic, which are continuing sources to form gas hydrates in the sediments of SCS. Here, Microbial ecosystems, particularly those involved in methane transformations were investigated in the cold seep areas (Qiongdongnan, Shenhu, and Dongsha) in the northern continental shelf of SCS. Multiple interdisciplinary analytic tools such as stable isotope probing, geochemical analysis, and molecular ecology, were applied for a comprehensive understanding of the microbe mediated methane transformation in this project. A variety of sediments cores have been collected, the geochemical profiles and the associated microbial distribution along the sediment cores were recorded. The major microbial groups involved in the methane transformation in these sediment cores were revealed, known methane producing and oxidizing archaea including Methanosarcinales, anaerobic methane oxidizing groups ANME-1, ANME-2 and their niche preference in the SCS sediments were found. In-depth comparative analysis revealed the presence of SCS-specific archaeal subtypes which probably reflected the evolution and adaptation of these methane metabolizing microbes to the SCS environmental conditions. Our work represents the first comprehensive analysis of the methane metabolizing microbial communities in the cold seep areas along the northern continental shelf of South China Sea, would provide new insight into the

  7. Cold seep carbonates along the Norwegian margin, insights into U-Th geochronology and S geochemistry

    NASA Astrophysics Data System (ADS)

    Cremiere, A.; Lepland, A.; Wing, B. A.; Sahy, D.; Condon, D. J.; Chand, S.; Noble, S. R.; Bui, T. H.; Thorsnes, T.; Brunstad, H.

    2015-12-01

    Cold seep carbonates along the Norwegian margin, insights into U-Th geochronology and S geochemistryAuthigenic carbonate crusts form in shallow subsurface of marine sediments due to the microbial anaerobic oxidation of methane (AOM). As a result they are unique archives of the locus and intensity of past methane seepage that can be dated by using U-daughter decay affording the unique opportunity to constrain the absolute timing of methane release events. Because AOM is mainly driven by the microbial reduction of seawater sulfate, multiple sulfur isotope compositions of paired carbonate-associated sulfate (CAS) and pyrite in seep carbonates taken as proxies for porewater sulfate and sulfide, respectively, have the potential to reconstruct the biogeochemical conditions under which seep carbonates precipitate. Methane-derived carbonate crusts were collected from several seepage sites on the Norwegian continental shelf, including sites in the North Sea, the Norwegian Sea and the Barents Sea. The U-Th dating results constrain the main episode of carbonate crust formation in the Barents and Norwegian seas during the time interval between 14 and 7 ka. Such ages suggest that the methane seepage along the northern Norwegian margin was most active after the collapse of the Scandinavian ice sheet and deglaciation of the area that took place at about 15 ka. The methane flux for the carbonate crust formation was likely provided by the dissociation of methane hydrates that extensively formed in underlying sediments during the last glacial period, but became unstable due to depressuring effects of retreating ice sheet. The precipitation of studied North Sea carbonate crusts occurred more recently, from 6 to 1 ka, suggesting that their formation is unrelated to the glacial history of the area. The paired sulfur stable isotope compositions of pyrite-CAS record a large range of fractionation factors (from 30 to 70 ‰) reflecting change of sulfate-reduction rates possibly controlled

  8. Fluid geochemistry of cold seeps and hydrothermal vents in the Guaymas Basin, Gulf of California

    NASA Astrophysics Data System (ADS)

    Hensen, Christian; Geilert, Sonja; Scholz, Florian; Schmidt, Mark; Liebetrau, Volker; Kipfer, Rolf; Sarkar, Sudipta; Doll, Mechthild

    2017-04-01

    In this study, we present geochemical data from pore fluids and gases that were sampled at cold seeps and hydrothermal vents in the Guaymas Basin during Sonne cruise 241. The Guaymas Basin is a unique environment where magma intrudes into thick sequences of organic-rich sediments, thereby maturing host rocks and releasing large amounts of hydrocarbons. Geochemical measurements performed on samples from a recently discovered high-temperature vent field (Berndt et al., 2016) clearly support this paradigm. 3He/4He ratios agree with that of excess He from the southern part of the Guaymas Basin (Lupton, 1979) and suggest the same general MORB source, while isotopic data of hydrocarbon gases largely indicate a thermogenic, sedimentary source. Heat flow measurements performed in the vicinity of the smoker site are extremely high, exceeding 10 W/m2, indicating that hydrocarbon gas production (mainly CH4) is related to contact heating due to magmatic activity near the hydrothermal vents. Cold seeps are located up to some tens of kilometres off the rift axis and are typically characterized by chemosynthetic fauna assemblages at the seafloor. The occurrence of the seeps has also been related to sill intrusions. Seismic records typically show evidence for sediment mobilization in the deeper subsurface and blanked zones due to gas accumulations directly beneath the seeps. Despite these visual and geophysical indications for deep-sourced heat-driven fluid flow, pore water data are not indicative for geochemical reactions taking place at elevated temperatures. Major dissolved constituents do not show strong deviations from seawater and dissolved methane is typically of biogenic origin. In addition, heat flow values do not deviate from regional averages, and hence, these findings contradict the existing hypothesis of a sill-driven mechanism responsible for the formation of seafloor seepage sites. A preliminary interpretation is that fluid and gas mobilisation from sill activity

  9. Bacterial communities and syntrophic associations involved in anaerobic oxidation of methane process of the Sonora Margin cold seeps, Guaymas Basin.

    PubMed

    Vigneron, Adrien; Cruaud, Perrine; Pignet, Patricia; Caprais, Jean-Claude; Gayet, Nicolas; Cambon-Bonavita, Marie-Anne; Godfroy, Anne; Toffin, Laurent

    2014-09-01

    The Sonora Margin cold seeps present on the seafloor a patchiness pattern of white microbial mats surrounded by polychaete and gastropod beds. These surface assemblages are fuelled by abundant organic inputs sedimenting from the water column and upward-flowing seep fluids. Elevated microbial density was observed in the underlying sediments. A previous study on the same samples identified anaerobic oxidation of methane (AOM) as the potential dominant archaeal process in these Sonora Margin sediments, probably catalysed by three clades of archaeal anaerobic methanotrophs (ANME-1, ANME-2 and ANME-3) associated with bacterial syntrophs. In this study, molecular surveys and microscopic observations investigating the diversity of Bacteria involved in AOM process, as well as the environmental parameters affecting the composition and the morphologies of AOM consortia in the Sonora Margin sediments were carried out. Two groups of Bacteria were identified within the AOM consortia, the Desulfosarcina/Desulfococcus SEEP SRB-1a group and a Desulfobulbus-related group. These bacteria showed different niche distributions, association specificities and consortia architectures, depending on sediment surface communities, geochemical parameters and ANME-associated phylogeny. Therefore, the syntrophic AOM process appears to depend on sulphate-reducing bacteria with different ecological niches and/or metabolisms, in a biofilm-like organic matrix. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. Trace element behaviour at cold seeps and the potential export of dissolved iron to the ocean

    NASA Astrophysics Data System (ADS)

    Lemaitre, Nolwenn; Bayon, Germain; Ondréas, Hélène; Caprais, Jean-Claude; Freslon, Nicolas; Bollinger, Claire; Rouget, Marie-Laure; de Prunelé, Alexis; Ruffine, Livio; Olu-Le Roy, Karine; Sarthou, Géraldine

    2014-10-01

    Seawater samples were collected by submersible above methane seeps in the Gulf of Guinea (Regab and Baboon pockmarks) in order to investigate the behaviour of iron (Fe), manganese (Mn) and rare earth elements (REE) during fluid seepage. Our aim was to determine whether cold seeps may represent potential sources of dissolved chemical species to the ocean. Dissolved (<0.45 μm filtered samples) and total dissolvable (unfiltered samples) concentrations were determined over ∼50 m long vertical transects above the seafloor and at various discrete locations within the pockmarks. We show that substantial amounts of Fe and Mn are released into seawater during seepage of methane-rich fluids. Mn is exported almost quantitatively in the dissolved form (more than 90% of total Mn; mean MnDISS∼12±11 nmol/kg). Although a significant fraction of Fe is bound to particulate phases, the dissolved iron pool still accounts on average for approximately 20 percent of total iron flux at vent sites (mean FeDISS∼22±11 nmol/kg). This dissolved Fe fraction also appears to remain stable in the water column. In contrast, there was no evidence for any significant benthic fluxes of pore water REE associated with fluid seepage at the studied sites. Overall, our results point towards distinct trace element behaviour during fluid seepage, with potential implications for the marine geochemical budget. The absence of any dissolved REE enrichments in bottom waters clearly indicates effective removal in sub-surface sediments. Most likely, precipitation of authigenic mineral phases at cold seeps (i.e. carbonates) represents a net sink for these elements. While Mn appears to behave near-conservatively during fluid seepage, the observed relative stability of dissolved Fe in the water column above seepage sites could be explained by complexation with strong organic ligands and/or the presence of Fe-bearing sulfide nanoparticles, as reported previously for submarine hydrothermal systems. Considering

  11. Sources of fluids and gases expelled at cold seeps offshore Georgia, eastern Black Sea

    NASA Astrophysics Data System (ADS)

    Reitz, Anja; Pape, Thomas; Haeckel, Matthias; Schmidt, Mark; Berner, Ulrich; Scholz, Florian; Liebetrau, Volker; Aloisi, Giovanni; Weise, Stephan M.; Wallmann, Klaus

    2011-06-01

    Four seep sites located within an ˜20 km 2 area offshore Georgia (Batumi seep area, Pechori Mound, Iberia Mound, and Colkheti Seep) show characteristic differences with respect to element concentrations, and oxygen, hydrogen, strontium, and chlorine isotope signatures in pore waters, as well as impregnation of sediments with petroleum and hydrocarbon potential. All seep sites have active gas seepage, near surface authigenic carbonates and gas hydrates. Cokheti Seep, Iberia Mound, and Pechori Mound are characterized by oil-stained sediments and gas seepage decoupled from deep fluid advection and bottom water intrusion induced by gas bubble release. Pechori Mound is further characterized by deep fluid advection of lower salinity pore fluids. The Pechori Mound pore fluids are altered by mineral/water reactions at elevated temperatures (between 60 and 110 °C) indicated by heavier oxygen and lighter chlorine isotope values, distinct Li and B enrichment, and K depletion. Strontium isotope ratios indicate that fluids originate from late Oligocene strata. This finding is supported by the occurrence of hydrocarbon impregnations within the sediments. Furthermore, light hydrocarbons and high molecular weight impregnates indicate a predominant thermogenic origin for the gas and oil at Pechori Mound, Iberia Mound, and Colkheti Seep. C 15+ hydrocarbons at the oil seeps are allochtonous, whereas those at the Batumi seep area are autochthonous. The presence of oleanane, an angiosperm biomarker, suggests that the hydrocarbon source rocks belong to the Maikopian Formation. In summary, all investigated seep sites show a high hydrocarbon potential and hydrocarbons of Iberia Mound, Colkheti Seep, and Pechori Mound are predominantly of thermogenic origin. However, only at the latter seep site advection of deep pore fluids is indicated.

  12. In situ Raman-based detections of the hydrothermal vent and cold seep fluids

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

    2016-04-01

    Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS-, SO42-, HSO4-, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42-, and the increase of CO2 and well resolved H2S and HS- peaks. At the white smoker of Onsen site the strong HSO4-peak observed at high temperature quickly dropped with strong accompanying increase of SO42-and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS- and CO2 signals. We also have detected the concentrations of CH4,H2S, HS-, SO42-, and S8 in cold seep fluids and the surrounding sediment pore water from

  13. Cold Seeps and Near-Surface Gas Hydrates Offshore Georgia, Eastern Black Sea

    NASA Astrophysics Data System (ADS)

    Klaucke, I.; Sahling, H.; Weinrebe, W.; Blinova, V.; Buerk, D.; Lursmanashvili, N.; Bohrmann, G.

    2005-12-01

    Multibeam bathymetry and high-resolution deep-towed sidescan sonar mapping allowed identifying several gas seeps and near-surface gas hydrate deposits in 850-900 metres water depth on the continental slope offshore Batumi, Georgia (Eastern Black Sea). Most of the seeps are located on a broad ridge named Kobuleti Ridge separating two canyons: the Supsa canyon north of the ridge and the deeply incised central canyon south of it. The southern wall of this canyon also shows signs for gas seeps. Gas seeps are shown by acoustic anomalies in the water column on raw sonar records and as high backscatter intensity area on processed data. The seeps on Kobuleti Ridge are characterised by carbonate deposits at the centre and a much wider area where gas hydrates are present. Fractures of a NW-SE direction are present at the seeps site and are probably related to the formation and decomposition of gas. Individual sites of gas emission apparently exert their influence for a circular area of up to 40-m in diameter. Gas geochemistry from gravity cores shows high gas content and a mixture of biogenic and thermogenic gases together with the presence of gas hydrates. The seeps offshore Georgia are of a new type of cold seeps in the Black Sea in addition to shallow water seeps of biogenic gas and deep water mud volcanoes. They are located in deep water within the zone of gas hydrate stability and are probably characterised by a very high gas flux from depth resulting and the coexistence of gas hydrates and free gas. These seeps show great similarity with gas hydrate deposits and cold seeps on Hydrate Ridge offshore Oregon.

  14. Overpressure and fluid flow in the new jersey continental slope: implications for slope failure and cold seeps

    PubMed

    Dugan; Flemings

    2000-07-14

    Miocene through Pleistocene sediments on the New Jersey continental slope (Ocean Drilling Program Site 1073) are undercompacted (porosity between 40 and 65%) to 640 meters below the sea floor, and this is interpreted to record fluid pressures that reach 95% of the lithostatic stress. A two-dimensional model, where rapid Pleistocene sedimentation loads permeable sandy silt of Miocene age, successfully predicts the observed pressures. The model describes how lateral pressure equilibration in permeable beds produces fluid pressures that approach the lithostatic stress where overburden is thin. This transfer of pressure may cause slope failure and drive cold seeps on passive margins around the world.

  15. Gas Seep-Induced Solute Transport into Submerged Sediments

    NASA Astrophysics Data System (ADS)

    Khalili, A.; Morad, M. R.; Malek Mohammadi, R.; Ahmerkamp, S.

    2015-12-01

    We investigated the downward migration of dye concentration mediated by air bubbles rising through a bed of sediment. The porous bed was composed of three samples of fire-dried quartz sands with coarse, medium and fine grains. The experimental setup is a rectangular container filled with a saturated sediment column overlaid by a dyed water layer. Air is injected centrally from the bottom of the container. The quantification of the total concentration uptake inside the sediment layer has been carried out experimentally using image processing technique. The spread of dye concentration from the overlying water into the sediment layer showed two distinct patterns, i.e. a conically developing shape for fine sand and horizontal front propagation for the medium and coarse ones. Based on the physical processes involved we introduce a novel pressure boundary condition for numerical simulation of the concentration uptake within the sediment layer that mimicked well the experimental observations. Furthermore, we obtained two empirical relations for the total concentration uptake as well as the dye propagation area as a function of the injected air. This finding plays a significant role for a quantitative estimation of downward flux of organic and particulate matter in the vicinity of gas seeps.

  16. Late Pliensbachian (Early Jurassic) Cold Seep Carbonates: Methane Release Prior to the Toarcian Oceanic Anoxic Event

    NASA Astrophysics Data System (ADS)

    van de Schootbrugge, B.; Harazim, D.; Sorichter, K.; Fiebig, J.; Zanella, F.; Oschmann, W.; Rosenthal, Y.

    2008-12-01

    We present evidence for methane seepage during the Early Jurassic (~ 185 Ma) in the form of newly discovered extensive occurrences of carbonate concretions that resemble the subsurface plumbing system of better known Cenozoic to Recent examples of cold seep carbonates. Columnar carbonate concretions of up to 1 m in length that are perpendicular to bedding, occur abundantly in the Upper Pliensbachian (upper Amaltheus margaritatus Zone, gibbosus Subzone) in outcrops in the vicinity of Riviere-sur-Tarn, southern France. Stable isotope analyses of these nodules show depleted δ13C values that decrease from the rim to the center from -18.8 to -25.7‰ (V-PDB), but normal marine δ18O values (-1.8‰). Computer tomographic (CT) scanning of the columnar concretions show one or more central canals that are lined or filled entirely with pyrite and late diagenetic minerals. Septarian cracks are also filled with secondary calcite and/or siderite. Based on our preliminary geochemical and sedimentological observations we suggest that these concretions formed as a combination of the anaerobic oxidation of methane (AOM) and sulfate reduction within the sediment. Previously, these concretions with one, two or more central tubes have been ascribed to the activity of an enigmatic organism, possibly with annelid or arthropod affinities, known as Tisoa siphonalis. Our results suggest tisoan structures are abiogenic. Interestingly, Tisoa siphonalis has been described from many locations in the Grands Causses Basin in southern France, and from northern France and Luxemburg, always occurring at the same stratigraphic level. Upper Pliensbachian cold seep carbonates thus possibly cover an area of several thousand square kilometers, largely distributed across the basin centres of the NW European epicontinental seaway. Our findings may have far reaching implications for understanding the Toarcian Oceanic Anoxic Event, which is interpreted to bear the hallmarks of catastrophic methane release

  17. Marine cold seeps and their manifestations: geological control, biogeochemical criteria and environmental conditions

    NASA Astrophysics Data System (ADS)

    Suess, Erwin

    2014-10-01

    Characteristics of cold seeps at different geologic settings are the subject of this review primarily based on results of the Research Consortium SFB 574. Criteria are drawn from examples on the erosive convergent margin off Costa Rica, the accretionary margin off Chile supplemented by examples from the transform margin of the Golf of Cadiz and the convergent Hikurangi margin off New Zealand. Others are from well-studied passive margins of the Black Sea, the Golf of Mexico, the eastern Mediterranean Sea and the South China Sea. Seeps at all settings transport water and dissolved compounds to the ocean through the seafloor by different forcing mechanism and from different depths of the submerged geosphere (10s of meters to 10s of km). The compounds sustain oasis-type ecosystems by providing bioactive reductants sulfide, methane and hydrogen. Hereby, the interaction between fluid composition, flux rates and biota results in a diagnostic hydrocarbon-metazoan-microbe-carbonate association; currently, well over 100 active sites are known. The single most important reaction is microbially mediated anaerobic oxidation of methane with secondary reactions involving S-biogeochemistry and carbonate mineral precipitation. Seep fluids and their seafloor manifestations provide clues as to source depth, fluid-sediment/rock interaction during ascent, lifetime and cyclicity of seepage events but less so on the magnitude of return flow. At erosive margins, Cl-depleted and B-enriched fluids from clay dehydration provide criteria for source depth and temperature. The upward material flow generates mud volcanoes at the seafloor above the projected location of dehydration at depth. At accretionary margins, fluids are derived from more shallow depths by compaction of sediments as they ride on the incoming oceanic plate; they are emitted through thrust faults. At highly sedimented margins, organic-rich and evaporite-containing strata (when present) determine the final fluid composition

  18. An overview of gas hydrate and cold seep research along the Hikurangi Margin, New Zealand (2006 & 2007)

    NASA Astrophysics Data System (ADS)

    Greinert, J.; Faure, K.; Naudts, L.; de Batist, M.; Bialas, J.; Linke, P.; Pecher, I.; Rowden, R.

    2009-04-01

    Prior to 2006, the knowledge about cold seeps around New Zealand was based mainly on accidental recovery of seep fauna or methane-derived carbonates by fishermen and the detection of flares in fish-finding sonars. Lewis and Marshall (1996; NZJGG) compiled these findings, providing the first details on 13 seep sites. Four of those are located at the Hikurangi Margin along the east coast of New Zealand's North Island. Since then, three international cruises in 2006 and 2007 enhanced our knowledge considerably about methane seepage along the Hikurangi Margin, an area which has widely distributed and in places very strong BSR. Two cruises on the RV TANGAROA (led by GNS Science and NIWA, NZ) in 2006 focused on extensive reconnaissance work (multibeam mapping, seismic surveys, flare imaging, visual observations) as well as fauna sampling, geochemical pore water analyses and CTD casts including water sampling for methane analyses. Several new seep sites were discovered during these cruises. Using these data, very detailed investigations in four main working areas could be performed during a 10-week expedition with RV SONNE (SO191, led by IFM-GEOMAR, Germany). All research topics currently discussed in the scientific community were addressed using state-of-the-art equipment (e.g. deep-tow side-scan, TV-guided sampling, lander and ROV-deployments). Fourteen institutes from seven countries were involved (Australia, Belgium, Germany, New Zealand, United Kingdom, United States, Switzerland). Echosounder and sidescan surveys unmistakably revealed active seep sites by detecting bubbles in the water column and carbonate precipitation at the seafloor forming massive chemoherm complexes. These complexes are associated with typical seep fauna like tube worms, bivalve mollusk species (Calyptogena, Bathymodiolus),and bacterial mats. At the fringe of these chemoherms dark sediment patches were observed which exihibit a novel seep habitat dominated by dense beds of two new species of

  19. Epizooic metazoan meiobenthos associated with tubeworm and mussel aggregations from cold seeps of the northern Gulf of Mexico.

    PubMed

    Bright, M; Plum, C; Riavitz, L A; Nikolov, N; Martinez Arbizu, P; Cordes, E E; Gollner, S

    2010-11-01

    The abundance and higher taxonomic composition of epizooic metazoan meiobenthic communities associated with mussel and tubeworm aggregations of hydrocarbon seeps at Green Canyon, Atwater Valley, and Alaminos Canyon in depths between 1400 and 2800 m were studied and compared to the infaunal community of non-seep sediments nearby. Epizooic meiofaunal abundances of associated meiobenthos living in tubeworm bushes and mussel beds at seeps were extremely low (usually <100 ind. 10 cm(-2)), similar to epizooic meiofauna at deep-sea hydrothermal vents, and the communities were composed primarily of nematodes, copepods, ostracods, and halacarids. In contrast, epizooic meiobenthic abundance is lower than previous studies have reported for infauna from seep sediments. Interestingly, non-seep sediments contained higher abundances and higher taxonomic diversity than epizooic seep communities, although in situ primary production is restricted to seeps.

  20. Epizooic metazoan meiobenthos associated with tubeworm and mussel aggregations from cold seeps of the northern Gulf of Mexico

    PubMed Central

    Bright, M.; Plum, C.; Riavitz, L.A.; Nikolov, N.; Martinez Arbizu, P.; Cordes, E.E.; Gollner, S.

    2010-01-01

    The abundance and higher taxonomic composition of epizooic metazoan meiobenthic communities associated with mussel and tubeworm aggregations of hydrocarbon seeps at Green Canyon, Atwater Valley, and Alaminos Canyon in depths between 1400 and 2800 m were studied and compared to the infaunal community of non-seep sediments nearby. Epizooic meiofaunal abundances of associated meiobenthos living in tubeworm bushes and mussel beds at seeps were extremely low (usually <100 ind. 10 cm−2), similar to epizooic meiofauna at deep-sea hydrothermal vents, and the communities were composed primarily of nematodes, copepods, ostracods, and halacarids. In contrast, epizooic meiobenthic abundance is lower than previous studies have reported for infauna from seep sediments. Interestingly, non-seep sediments contained higher abundances and higher taxonomic diversity than epizooic seep communities, although in situ primary production is restricted to seeps. PMID:21264038

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

    NASA Astrophysics Data System (ADS)

    Kravchishina, M. D.; Lein, A. Yu.; Savvichev, A. S.; Reykhard, L. E.; Dara, O. M.; Flint, M. V.

    2017-01-01

    Authigenic minerals were studied in Holocene shelf sediments of the Laptev Sea (cold methane seep site, water depth 71 m). The study presents the first finds of large hard carbonate concretions with Mg-calcite cement in recent sediments of the Arctic shelf seas. These concretions differ from previously reported glendonites and concretions from bottom sediments of the White Sea, Kara Sea, Sea of Okhotsk, etc. A study of the morphology, microstructure, and composition of these newly reported concretions revealed the multistage formation of carbonates (structural varieties of Mg-calcite and aragonite). It was shown that organic matter played an important role in the formation of authigenic carbonates, i.e., in the formation of sedimentary-diagenetic Mg-calcite. The role of methane as a possible source for authigenic carbonate formation was estimated. It was found that methane-derived Mg-calcite accounts for 17-35% of concretion materials. Mg-calcite had δ13C-Ccarb values between-24 and-23‰ and δ13C-Corg values between-44.5 and-88.5‰.

  2. Development of a new deep-sea hybrid Raman insertion probe and its application to the geochemistry of hydrothermal vent and cold seep fluids

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Lian, Chao; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

    2017-05-01

    Hydrothermal vent fluids, cold seep fluids, their associated chemosynthetic communities, and the biogeochemical anaerobic oxidation of methane (AOM) play very important roles in the biogeochemical sulfur and carbon cycles in the ocean. Based on our previous success developing and deploying a deep-sea sediment pore water Raman probe, we developed a new deep-sea hybrid Raman insertion probe (RiP) designed to operate at temperatures up to 450 °C that can be inserted directly into high-temperature fluids emerging from hydrothermal vents. By routinely exchanging the various tips and optics of the probe, we can analyze the geochemistry of hydrothermal vent fluids, cold seep fluids, and sediment pore water profiles (0-60 cm) in situ. The instrument ensemble also includes a new deep-sea laser Raman spectrometer in a custom-designed, 6000-m titanium pressure housing, which is powered, controlled and deployed by the remotely operated vehicle (ROV) Faxian down to a maximum water depth of 4500 m. The new RiP was deployed at the Izena Hole hydrothermal area in the middle Okinawa Trough back-arc basin; the Papua-Australia-Canada-Manus (PACManus) hydrothermal vent area in the Manus back-arc basin, Papua New Guinea; and a cold seep field at Formosa Ridge in the northern South China Sea. The Raman peaks of CO2, CH4, H2S, HS-, SO42- and S8 were obtained in situ from high-temperature hydrothermal vents (290 °C), low-temperature cold seep fluids (2 °C) and the surrounding sediment pore water. Dissolved CH4 and S8 were identified for the first time in the fluids under the lush chemosynthetic communities of the cold seep. Several sediment pore water profiles collected near the cold seep were characterized by the loss of SO42- and increased CH4, H2S and HS- peaks. Additionally, the in situ pH range of the pore water profile was between 6.95 and 7.22. Thus, the RiP system provides a very useful tool for investigating the geochemistry of hydrothermal vent and cold seep fluids.

  3. Biogeography of thermophilic, endospore-forming bacteria in deepwater hydrocarbon seep sediments of the Eastern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Chakraborty, A.; Hubert, C. R.; Ellefson, E.

    2016-12-01

    Dormant endospores of thermophilic bacteria (thermospores) are routinely detected in permanently cold marine surface sediments and are an example of the microbial rare biosphere. These endospores remain undetected in nucleic-acid based community surveys, but can germinate and proliferate during high-temperature incubations. Prominent genera of thermospores include sulfate-reducing Desulfotomaculum and Pelotomaculum as well as fermentative Caloranaerobacter and Thermicanus, within the phylum Firmicutes. Many thermospores are closely related to microorganisms indigenous to subseafloor petroleum reservoirs. If thermospores found in the cold seabed originate warm subsurface petroleum reservoirs, hydrocarbon seeps are likely natural conduits for their passive dispersal up into the ocean. As such, thermospore distributions in marine sediments might have utility in detection of natural hydrocarbon seeps. Marine surface sediments from 112 locations in the Eastern Gulf of Mexico ranging from 100 to 3300 m water depth and situated 6 to 600 km away from each other were sampled and classified according to geochemical indications of oil seepage. Sediment microcosms amended with 20 mM sulfate and a mixture of organic substrates were pasteurized at 80°C then incubated at 50-55°C for 14 days. Sulfate reduction was monitored and detected in 84 (75%) of the sediment samples. The rate and extent of sulfate reduction at this high temperature was greater in the oil-containing sediments than in the sediments without oil. Sequencing of the V3-V4 region of the 16S rRNA gene on an Illumina MiSeq benchtop sequencer before and after high temperature incubations revealed enrichments of various thermospore genera with the majority being closely related to bacteria previously detected in deep subsurface environments. These results are consistent with the hypothesis that thermospores in the vicinity of hydrocarbon seeps originate from warm deep biosphere habitats.

  4. Cold seep status archived in authigenic carbonates: Mineralogical and isotopic evidence from Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Sun, Xiaoming; Lin, Zhiyong; Xu, Li; Gong, Junli; Lu, Hongfeng

    2015-12-01

    Cold-seep carbonates are precipitated under high alkalinity conditions created by the anaerobic oxidation of methane in cold-seep sites. Multiple Ca-Mg-carbonate phases are identified, including aragonite, low-Mg calcite (LMC), high-Mg calcite (HMC), protodolomite, and dolomite. These phases result from different conditions that are related with cold-seep activities. Here, we report on the relationship between the Ca-Mg-carbonate phases and the cold-seep status. Authigenic carbonates were sampled from northern slope of South China Sea. Carbon isotopic compositions of samples from Shenhu area are lower than -40‰, indicating methane-derived carbon. The δ13C values of samples from Southwest (SW) Taiwan area range from ~-30‰ to ~-20‰, which is the result of the mixture of methane carbon and seawater carbon. Carbonate phases were identified according to the composition and structure results. Samples from Shenhu area are composed of protodolomite and HMC. Three zones were discovered from the center to the rim of the cross-section of the tube-like sample from SW Taiwan area. From the external to the internal zones, the carbonate phases are HMC; LMC and protodolomite; HMC, respectively. The intensity of superstructure reflections of the protodolomite from Shenhu area is stronger than that from SW Taiwan area, indicating higher MgCO3 content. Based on the formation conditions of Ca-Mg-carbonates from LMC to dolomite, those with higher MgCO3 content are formed in more active cold-seep environment. According to the distribution of carbonate phases in each sample, the cold seep flux was high in Shenhu area and was sustained for a long time. By contrast, the flux in SW Taiwan area was relatively low and not stable. It once became higher, but finally returned to low.

  5. Diversity, abundance and distribution of amoA-encoding archaea in deep-sea methane seep sediments of the Okhotsk Sea.

    PubMed

    Dang, Hongyue; Luan, Xi-Wu; Chen, Ruipeng; Zhang, Xiaoxia; Guo, Lizhong; Klotz, Martin G

    2010-06-01

    The ecological characteristics of amoA-encoding archaea (AEA) in deep-sea sediments are largely unsolved. This paper aimed to study the diversity, structure, distribution and abundance of the archaeal community and especially its AEA components in the cold seep surface sediments of the Okhotsk Sea, a marginal sea harboring one of the largest methane hydrate reservoirs in the world. Diverse archaeal 16S rRNA gene sequences were identified, with the majority being related to sequences from other cold seep and methane-rich sediment environments. However, the AEA diversity and abundance were quite low as revealed by amoA gene analyses. Correlation analysis indicates that the abundance of the archaeal amoA genes was correlated with the sediment organic matter content. Thus, it is possible that the amoA-carrying archaea here might utilize organic matter for a living. The affiliation of certain archaeal amoA sequences to the GenBank sequences originally obtained from deep-sea hydrothermal vent environments indicated that the related AEA either have a wide range of temperature adaptation or they have a thermophilic evolutionary history in the modern cold deep-sea sediments of the Okhotsk Sea. The dominance of ammonia-oxidizing bacteria over AEA may indicate that bacteria play a significant role in nitrification in the Okhotsk Sea cold seep sediments.

  6. Application of parasound data for sediment study on methane seep site at Simeulue basin

    NASA Astrophysics Data System (ADS)

    Wiguna, Taufan; Ardhyastuti, Sri

    2015-09-01

    The Parasound data presents sea depth and sub-bottom profiler. In terms of geological terminology, parasound data represents significant recent surface sedimentary structures that valuable for the selection of subsequent sampling site such as sampling at methane seep site. Therefore, Parasound is used to detailing methane seep at surface sediment following seismic data interpretation. In this study, parasound is used to focus observe area especially for sediment study on methane seep site. The Parasound systems works both as narrow beam sounder use high frequency and as sediment echosounder use low frequency. Parasound acquisition applies parametric effect. It produces additional frequency by nonlinear acoustic interaction of finite amplitude waves. Parasound transducers have 128 elements on 1 m2 and need transmission power up to 70 kW. The results of this study are discovered large seep carbonate with porous surface which means there are gas expulsions passing through that rock.

  7. Application of parasound data for sediment study on methane seep site at Simeulue basin

    SciTech Connect

    Wiguna, Taufan Ardhyastuti, Sri

    2015-09-30

    The Parasound data presents sea depth and sub-bottom profiler. In terms of geological terminology, parasound data represents significant recent surface sedimentary structures that valuable for the selection of subsequent sampling site such as sampling at methane seep site. Therefore, Parasound is used to detailing methane seep at surface sediment following seismic data interpretation. In this study, parasound is used to focus observe area especially for sediment study on methane seep site. The Parasound systems works both as narrow beam sounder use high frequency and as sediment echosounder use low frequency. Parasound acquisition applies parametric effect. It produces additional frequency by nonlinear acoustic interaction of finite amplitude waves. Parasound transducers have 128 elements on 1 m2 and need transmission power up to 70 kW. The results of this study are discovered large seep carbonate with porous surface which means there are gas expulsions passing through that rock.

  8. Anaerobic Oxidation of Methane at a Marine Methane Seep in a Forearc Sediment Basin off Sumatra, Indian Ocean.

    PubMed

    Siegert, Michael; Krüger, Martin; Teichert, Barbara; Wiedicke, Michael; Schippers, Axel

    2011-01-01

    A cold methane seep was discovered in a forearc sediment basin off the island Sumatra, exhibiting a methane-seep adapted microbial community. A defined seep center of activity, like in mud volcanoes, was not discovered. The seep area was rather characterized by a patchy distribution of active spots. The relevance of anaerobic oxidation of methane (AOM) was reflected by (13)C-depleted isotopic signatures of dissolved inorganic carbon. The anaerobic conversion of methane to CO(2) was confirmed in a (13)C-labeling experiment. Methane fueled a vital microbial community with cell numbers of up to 4 × 10(9) cells cm(-3) sediment. The microbial community was analyzed by total cell counting, catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), quantitative real-time PCR (qPCR), and denaturing gradient gel electrophoresis (DGGE). CARD-FISH cell counts and qPCR measurements showed the presence of Bacteria and Archaea, but only small numbers of Eukarya. The archaeal community comprised largely members of ANME-1 and ANME-2. Furthermore, members of the Crenarchaeota were frequently detected in the DGGE analysis. Three major bacterial phylogenetic groups (δ-Proteobacteria, candidate division OP9, and Anaerolineaceae) were abundant across the study area. Several of these sequences were closely related to the genus Desulfococcus of the family Desulfobacteraceae, which is in good agreement with previously described AOM sites. In conclusion, the majority of the microbial community at the seep consisted of AOM-related microorganisms, while the relevance of higher hydrocarbons as microbial substrates was negligible.

  9. Anaerobic Oxidation of Methane at a Marine Methane Seep in a Forearc Sediment Basin off Sumatra, Indian Ocean

    PubMed Central

    Siegert, Michael; Krüger, Martin; Teichert, Barbara; Wiedicke, Michael; Schippers, Axel

    2011-01-01

    A cold methane seep was discovered in a forearc sediment basin off the island Sumatra, exhibiting a methane-seep adapted microbial community. A defined seep center of activity, like in mud volcanoes, was not discovered. The seep area was rather characterized by a patchy distribution of active spots. The relevance of anaerobic oxidation of methane (AOM) was reflected by 13C-depleted isotopic signatures of dissolved inorganic carbon. The anaerobic conversion of methane to CO2 was confirmed in a 13C-labeling experiment. Methane fueled a vital microbial community with cell numbers of up to 4 × 109 cells cm−3 sediment. The microbial community was analyzed by total cell counting, catalyzed reporter deposition–fluorescence in situ hybridization (CARD–FISH), quantitative real-time PCR (qPCR), and denaturing gradient gel electrophoresis (DGGE). CARD–FISH cell counts and qPCR measurements showed the presence of Bacteria and Archaea, but only small numbers of Eukarya. The archaeal community comprised largely members of ANME-1 and ANME-2. Furthermore, members of the Crenarchaeota were frequently detected in the DGGE analysis. Three major bacterial phylogenetic groups (δ-Proteobacteria, candidate division OP9, and Anaerolineaceae) were abundant across the study area. Several of these sequences were closely related to the genus Desulfococcus of the family Desulfobacteraceae, which is in good agreement with previously described AOM sites. In conclusion, the majority of the microbial community at the seep consisted of AOM-related microorganisms, while the relevance of higher hydrocarbons as microbial substrates was negligible. PMID:22207865

  10. Differential methane oxidation activity and microbial community composition at cold seeps in the Arctic off western Svalbard

    NASA Astrophysics Data System (ADS)

    Gründger, Friederike; Svenning, Mette M.; Niemann, Helge; Silyakova, Anna; Serov, Pavel; Li Hong, Wei; Wegener, Gunter; Panieri, Giuliana; Carroll, JoLynn

    2016-04-01

    Most models considering climate change related bottom water warming suggest that gas hydrates may become destabilized, leading to the mobilization of methane into seabed and water column ecosystems, and, eventually, into the atmosphere. However, the capacity of methanotrophic microbes retaining methane in sediments and the hydrosphere is not well constrained. Here, we investigate the microbial utilization of methane in sediments and the water column, focusing on cold seeps discovered at the arctic continental margin of western Svalbard. We measured ex situ rates of methane oxidation and sulfate reduction in two active gas flare sites with different geological settings at the Vestnesa Ridge (1204 m water depth) and within a pingolike feature area southwest off Svalbard (PLF; 380 m water depth). Our results show contrarily situations at our two sampling sites: At Vestnesa Ridge we find high methane oxidation rates with values up to 2055 nmol cm-3 d-1 at the sediment surface where the sediments are oversaturated with methane. Whereas, methane concentration and oxidation rates are low in the overlying water column (2 pmol cm-3 d-1). In contrast, at the sediment surface at PLF methane concentration and oxidation rates are considerably lower (up to 1.8 nmol cm-3 d-1). While the overlying bottom water contains high concentration of methane and shows oxidation rates with values of up to 3.8 nmol cm-3 d-1. The data on methane oxidation and sulfate reduction activity are compared to the sediment geochemistry and to data from metagenomic analysis identifying the methanotrophic community composition. These results provide unique insight into the dynamic responses of the seabed biological filter at cold seeps in the Arctic off western Svalbard. This study is part of the Centre for Arctic Gas Hydrate, Environment and Climate and was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259.

  11. Differential methane oxidation activity and microbial community composition at cold seeps in the Arctic off western Svalbard

    NASA Astrophysics Data System (ADS)

    Grundger, F.; Svenning, M. M.; Niemann, H.; Silyakova, A.; Serov, P.; Hong, W. L.; Wegener, G.; Panieri, G.; Carroll, J.

    2016-02-01

    Most models considering climate change related bottom water warming suggest that gas hydrates may become destabilized, leading to the mobilization of methane into seabed and water column ecosystems, and, eventually, into the atmosphere. However, the capacity of methanotrophic microbes retaining methane in sediments and the hydrosphere is not well constrained. Here, we investigate the microbial utilization of methane in sediments and the water column, focusing on cold seeps discovered at the arctic continental margin of western Svalbard. We measured ex situ rates of methane oxidation and sulfate reduction in two active gas flare sites with different geological settings at the Vestnesa Ridge (1204 m water depth) and within a pingo-like feature area southwest off Svalbard (PLF; 380 m water depth). Our results show contrarily situations at our two sampling sites: At Vestnesa Ridge we find high methane oxidation rates with values up to 2055 nmol cm-3 d-1 at the sediment surface where the sediments are oversaturated with methane. Whereas, methane concentration and oxidation rates are low in the overlying water column (2 pmol cm-3 d-1). In contrast, at the sediment surface at PLF methane concentration and oxidation rates are considerably lower (up to 1.8 nmol cm-3 d-1). While the overlying bottom water contains high concentration of methane and shows oxidation rates with values of up to 3.8 nmol cm-3 d-1. The data on methane oxidation and sulfate reduction activity are compared to the sediment geochemistry and to data from metagenomic analysis identifying the methanotrophic community composition. These results provide unique insight into the dynamic responses of the seabed biological filter at cold seeps in the Arctic off western Svalbard.

  12. Patterns of subsurface fluid-flow at cold seeps: the Hikurangi Margin, offshore New Zealand

    NASA Astrophysics Data System (ADS)

    Krabbenhoeft, A.; Bialas, J.; Klaucke, I.; Crutchley, G. J.; Papenberg, C. A.; Netzeband, G. L.

    2012-12-01

    Based on multichannel seismic, geoacoustic, and methane sensor data, four different areas along the Hikurangi Margin show multiple indications for seep activity including bright spots, transparent zones, vertical chimneys, and the occurrence and distribution of bottom simulating reflectors. Locations where these features reach the seafloor are characterised by high backscatter intensity on sidescan sonar images and transparent zones in sediment echosounder profiles, while methane sensors show episodic, elevated methane concentrations near the seep sites. Methane discharge is facilitated by reduced hydrostatic pressure during low tides. The greatest number of seeps at Opouawe Bank correlates with the highest methane activity along the Hikurangi Margin. High heat flow values on flanks of ridges and low heat flow values on anticlines reflect a topographic effect on subsurface temperatures. Elevated heat flow occurs in the vicinity of seeps on Opouawe Bank. We propose that there are two drivers behind methane seepage with respect to the migration pathways of methane through the gas hydrate stability zone (GHSZ) to the seafloor: (1) structurally controlled and (2) stratigraphically controlled. In the structural model, vertical chimneys are the major pathways for methane through the GHSZ. Part of the upwardly migrating methane forms gas hydrate within the chimney. In the stratigraphic model, methane migration is stratigraphically controlled beneath seeps that are located on bathymetric highs and/or where subsurface anticlines occur beneath seeps. The structurally controlled seeps produce higher methane escape at the seafloor than those that are stratigraphically controlled. A combination of both driving mechanisms results in the highest methane seepage rates at the Tui Seep on Opouawe Bank.

  13. The vesicomyid bivalve habitat at cold seeps supports heterogeneous and dynamic macrofaunal assemblages

    NASA Astrophysics Data System (ADS)

    Guillon, Erwan; Menot, Lénaïck; Decker, Carole; Krylova, Elena; Olu, Karine

    2017-02-01

    The high biodiversity found at cold seeps, despite elevated concentrations of methane and hydrogen sulfide, is attributed to multiple sources of habitat heterogeneity. In addition to geological and geochemical processes, biogenic habitats formed by large symbiont-bearing taxa, such as bivalves and siboglinid tubeworms, or by microbial mats drive the biodiversity of small-sized fauna. However, because these habitat-forming species also depend on geochemical gradients, the respective influence of abiotic and biotic factors in structuring associated macrofaunal communities is often unresolved. The giant pockmark Regab located at 3200 m depth on the Congo margin is characterized by different fluid-flow regimes, providing a mosaic of the most common biogenic habitats encountered at seeps: microbial mats, mussel beds, and vesicomyid clam beds; the latter being distributed along a gradient of environmental conditions from the center to the periphery of the pockmark. Here, we examined the structure of macrofaunal communities in biogenic habitats formed in soft sediment to (1) determine the influence of the habitats on the associated macrofaunal communities (inter-habitat comparison), (2) describe how macrofaunal communities vary among vesicomyid clam beds (intra-habitat comparison) and (3) assess the inter-annual variation in vesicomyid beds based on repeated sampling at a three-year interval. The highest densities were found in the microbial mat communities in intermediate fluid-flow areas, but they had low diversity - also observed in the sediment close to mussel beds. In contrast, vesicomyid beds harbored the highest diversity. The vesicomyid beds did not show a homogeneous macrofaunal community across sampled areas; instead, density and composition of macrofauna varied according to the location of the beds inside the pockmark. The clam bed sampled in the most active, central part of the pockmark resembled bacterial mat communities by the presence of highly sulfide

  14. Deep-sea methane seep sediments in the Okhotsk Sea sustain diverse and abundant anammox bacteria.

    PubMed

    Shao, Sudong; Luan, Xiwu; Dang, Hongyue; Zhou, Haixia; Zhao, Yakun; Liu, Haitao; Zhang, Yunbo; Dai, Lingqing; Ye, Ying; Klotz, Martin G

    2014-02-01

    Marginal sea methane seep sediments sustain highly productive chemosynthetic ecosystems and are hotspots of intense biogeochemical cycling. Rich methane supply stimulates rapid microbial consumption of oxygen; these systems are thus usually hypoxic to anoxic. This and reported evidence for resident nitrogen fixation suggest the presence of an anaerobic ammonium-oxidizing (anammox) bacterial community in methane seep sediments. To test this hypothesis, we employed detection of genes encoding 16S rRNA gene and hydrazine dehydrogenase (hzo) to investigate the structure, abundance and distribution of the anammox bacterial community in the methane seep sediments of the Okhotsk Sea. Diverse complements of Candidatus Scalindua-related 16S rRNA and hzo gene sequences were obtained. Most of the deep-sea sites harbored abundant hzo genes with copy numbers as high as 10(7)  g(-1) sediment. In general, anammox bacterial signatures were significantly more abundant in the deep-water sediments. Sediment porewater NO3-, NOx- (i.e. NO3- + NO2-), NOx-/NH4+ and sediment silt content correlated with in situ distribution patterns of anammox bacterial marker genes, likely because they determine anammox substrate availability and sediment geochemistry, respectively. The abundance and distribution of anammox bacterial gene markers indicate a potentially significant contribution of anammox bacteria to the marine N cycle in the deep-sea methane seep sediments. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Possible roles of uncultured archaea in carbon cycling in methane-seep sediments

    NASA Astrophysics Data System (ADS)

    Yoshinaga, Marcos Y.; Lazar, Cassandre S.; Elvert, Marcus; Lin, Yu-Shih; Zhu, Chun; Heuer, Verena B.; Teske, Andreas; Hinrichs, Kai-Uwe

    2015-09-01

    Studies on microbial carbon cycling uniformly confirm that anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria represent the dominant and most active fraction of the sedimentary microbial community in methane-seep sediments. However, little is known about other frequently observed and abundant microbial taxa, their role in carbon cycling and association with the anaerobic oxidation of methane (AOM). Here, we provide a comprehensive characterization of stable carbon isotopes (δ13C) from several intact polar lipid (IPL) classes and metabolite pools in a downcore profile at a cold seep within the oxygen minimum zone off Pakistan. We aimed to evaluate microbial carbon metabolism using IPLs in relation to redox conditions, metabolites and 16S rRNA gene libraries. The 13C-depleted signature of carbon pools and microbial metabolites in pore waters (e.g., dissolved inorganic carbon, lactate and acetate) demonstrated high accumulation of AOM-associated biomass and subsequent turnover thereof. ANMEs accounted for a small fraction of the archaeal 16S rRNA gene survey, whereas sequences of other uncultured benthic archaea dominated the clone libraries, particularly the Marine Benthic Group D. On the basis of lipid diversity and carbon isotope information, we suggest that structurally diverse phospho- and glycolipids, including the recently identified unsaturated tetraethers that are particularly abundant in this setting, are likely derived from archaea other than ANMEs. Through the evaluation of δ13C values of individual IPL, our results indicate heterotrophy as a possible metabolic pathway of archaea in these AOM-dominated sediments.

  16. Shell growth and environmental control of methanophyllic Thyasirid bivalves from Svalbard cold seeps

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Åström, Emmelie; Ambrose, William; Locke, William; Oliver, Graham; Hong, Wei-Li; Carroll, JoLynn

    2016-04-01

    The analysis of molluscan shell material (sclerochronology) can provide information about an organism's age, growth history, and environmental conditions during its lifetime. Bivalve molluscs are common members of hydrothermal vents and methane cold seeps communities where, supported by chemosynthetic symbionts, they can reach high density and biomass. But little is known about methane-associated bivalve populations inhabiting high-Arctic cold seeps, and sclerochronological analysis of methane-influenced bivalves is rare. We measured growth rates and elemental and isotopic shell signatures in a newly discovered species of bivalve (Thyasiridae) from cold seeps at 350-390m depth southwest of Svalbard. First discovered in 2014, recently described shells of Thyasira capitanea sp.nov. were found at 2 independent seep systems in Storfjordrenna. Mean shell carbon isotopic ratios from inorganic δ13C (mean = -4.8‰) and organic δ13C (mean = -26.9‰) fractions clearly indicate a methane influenced habitat and food source for these organisms. Shell mineral ratios (Li/Ca, Mg/Ca, Mn/Ca, Fe/Ca, Sr/Ca, Ba/Ca, Pb/Ca) sampled along the axis of growth with laser-ablated ICP-MS exhibit variability through time and between sites, suggesting that concentrations of these elements that may be affected by methane emissions. The mineralogical data also elucidates the internal pattern of shell deposition and growth checks, and combined with the isotopic and growth rate data, enables us to interpret the temporal history of methane release from these locations.

  17. [Methanotrophic bacteria in cold seeps of the floodplains of northern rivers].

    PubMed

    Belova, S É; Oshkin, I Iu; Glagolev, M V; Lapshina, E D; Maksiutov, Sh Sh; Dedysh, S N

    2013-01-01

    Small mud volcanoes (cold seeps), which are common in the floodplains of northern rivers, are a potentially important, although poorly studied sources of atmospheric methane. Field research on the cold seeps of the Mukhrina River (Khanty-Mansiysk Autonomous okrug, Russia) revealed methane fluxes from these structures to be orders of magnitude higher than from equivalent areas of the mid-taiga bogs. Microbial communities developing around the seeps were formed under conditions of high methane concentrations, low temperatures (3-5 degrees C), and near-neutral pH. Molecular identification of methane-oxidizing bacteria from this community by analysis of the pmoA gene encoding particulate methane monooxygenase revealed both type I and type II methanotrophs (classes Gammaproteobacteria and Alphaproteobacteria, respectively), with predomination of type I methanotrophs. Among the latter, microorganisms related to Methylobacterpsychrophilus and Methylobacter tundripaludum, Crenothrix polyspora (a stagnant water dweller), and a number of methanotrophs belonging to unknown taxa were detected. Growth characteristics of two isolates were determined. Methylobactersp. CMS7 exhibited active growth at 4-10 degrees C, while Methylocystis sp. SB12 grew better at 20 degrees C. Experimental results confirmed the major role ofmethanotrophic gammaproteobacteria in controlling the methane emission from cold river seeps.

  18. Microbial communities in methane seep sediments along US Atlantic Margin are structured by organic matter and seepage dynamics

    NASA Astrophysics Data System (ADS)

    Graw, M. F.; Pohlman, J.; Treude, T.; Ruppel, C. D.; Colwell, F. S.

    2016-12-01

    Methane seeps are dynamic environments on continental margins where subsurface methane reaches the ocean. Microbial communities play a critical role in carbon cycling within seep sediments via organic carbon degradation, methane production, and anaerobic oxidation of methane (AOM), which consumes 20-80% of methane in seep sediments. However, biogeochemical controls on microbial community structure at seeps on a margin-wide scale remain unclear. The passive US Atlantic Margin (USAM) has been identified as a region of active methane seepage. Passive margin seeps have traditionally been understudied relative to seeps on active margins. Passive margins exhibit large cross-margin variability in organic carbon deposition and are anticipated to have divergent seep dynamics from active margins. Thus, the USAM offers a unique opportunity to investigate controls on microbial communities in seep sediments. We undertook analysis of microbial communities inhabiting seep sediments at 6 biogeochemically distinct sites along the USAM. Microbiological samples were co-located with measurements of sediment geochemistry and AOM and sulfate reduction rates. Illumina sequencing of the 16S rRNA gene, using both universal (83 samples) and archaeal-specific (64 samples) primers, and the mcrA gene (18 samples) identified 44 bacterial phyla and 7 archaeal phyla. Seeps in canyons and on open slope, likely representing high and low organic content sediments, hosted distinct communities; the former was dominated by ammonia-oxidizing Marine Group I Thaumarchaeota and the latter by mixotrophic Hadesarchaeota. Seep stability also impacted microbial community structure, and in particular the establishment of an AOM community rather than a Bathyarchaeota-dominated community. These findings contribute to understanding how microbial communities are structured within methane seep sediments and pave the way for investigating broad differences in carbon cycling between seeps on passive and active margins.

  19. Biogeography and potential exchanges among the atlantic Equatorial belt cold-seep faunas.

    PubMed

    Olu, Karine; Cordes, Erik E; Fisher, Charles R; Brooks, James M; Sibuet, Myriam; Desbruyères, Daniel

    2010-08-05

    Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300 m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000 m, with the middle slope sites either grouped with those deeper than 2000 m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as "stepping stones" for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further

  20. Biogeography and Potential Exchanges Among the Atlantic Equatorial Belt Cold-Seep Faunas

    PubMed Central

    Olu, Karine; Cordes, Erik E.; Fisher, Charles R.; Brooks, James M.; Sibuet, Myriam; Desbruyères, Daniel

    2010-01-01

    Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000m, with the middle slope sites either grouped with those deeper than 2000m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as “stepping stones” for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further

  1. Characterization of the acidic cold seep emplaced jarositic Golden Deposit, NWT, Canada, as an analogue for jarosite deposition on Mars

    NASA Astrophysics Data System (ADS)

    Battler, Melissa M.; Osinski, Gordon R.; Lim, Darlene S. S.; Davila, Alfonso F.; Michel, Frederick A.; Craig, Michael A.; Izawa, Matthew R. M.; Leoni, Lisa; Slater, Gregory F.; Fairén, Alberto G.; Preston, Louisa J.; Banerjee, Neil R.

    2013-06-01

    Surficial deposits of the OH-bearing iron sulfate mineral jarosite have been observed in several places on Mars, such as Meridiani Planum and Mawrth Vallis. The specific depositional conditions and mechanisms are not known, but by comparing martian sites to analogous locations on Earth, the conditions of formation and, thus, the martian depositional paleoenvironments may be postulated. Located in a cold semi-arid desert ˜100 km east of Norman Wells, Northwest Territories, Canada, the Golden Deposit (GD) is visible from the air as a brilliant golden-yellow patch of unvegetated soil, approximately 140 m × 50 m. The GD is underlain by permafrost and consists of yellow sediment, which is precipitating from seeps of acidic, iron-bearing groundwater. On the surface, the GD appears as a patchwork of raised polygons, with acidic waters flowing from seeps in troughs between polygonal islands. Although UV-Vis-NIR spectral analysis detects only jarosite, mineralogy, as determined by X-ray diffraction and inductively coupled plasma emission spectrometry, is predominantly natrojarosite and jarosite, with hydronium jarosite, goethite, quartz, clays, and small amounts of hematite. Water pH varies significantly over short distances depending on proximity to acid seeps, from 2.3 directly above seeps, to 5.7 several m downstream from seeps within the deposit, and up to 6.5 in ponds proximal to the deposit. Visual observations of microbial filament communities and phospholipid fatty acid analyses confirm that the GD is capable of supporting life for at least part of the year. Jarosite-bearing sediments extend beneath vegetation up to 70 m out from the deposit and are mixed with plant debris and minerals presumably weathered from bedrock and glacial till. This site is of particular interest because mineralogy (natrojarosite, jarosite, hematite, and goethite) and environmental conditions (permafrost and arid conditions) at the time of deposition are conceivably analogous to jarosite

  2. Transpressional segment boundaries in strike-slip fault systems offshore southern California: Implications for fluid expulsion and cold seep habitats

    NASA Astrophysics Data System (ADS)

    Maloney, Jillian M.; Grupe, Benjamin M.; Pasulka, Alexis L.; Dawson, Katherine S.; Case, David H.; Frieder, Christina A.; Levin, Lisa A.; Driscoll, Neal W.

    2015-05-01

    The importance of tectonics and fluid flow in controlling cold seep habitats has long been appreciated at convergent margins but remains poorly understood in strike-slip systems. Here we present geophysical, geochemical, and biological data from an active methane seep offshore from Del Mar, California, in the inner California borderlands (ICB). The location of this seep appears controlled by localized transpression associated with a step in the San Diego Trough fault zone and provides an opportunity to examine the interplay between fluid expulsion and restraining step overs along strike-slip fault systems. These segment boundaries may have important controls on seep locations in the ICB and other margins characterized by strike-slip faulting (e.g., Greece, Sea of Marmara, and Caribbean). The strike-slip fault systems offshore southern California appear to have a limited distribution of seep sites compared to a wider distribution at convergent plate boundaries, which may influence seep habitat diversity and connectivity.

  3. Metatranscriptomic analysis of diminutive Thiomargarita-like bacteria ("Candidatus Thiopilula" spp.) from abyssal cold seeps of the Barbados Accretionary Prism.

    PubMed

    Jones, Daniel S; Flood, Beverly E; Bailey, Jake V

    2015-05-01

    Large sulfur-oxidizing bacteria in the family Beggiatoaceae are important players in the global sulfur cycle. This group contains members of the well-known genera Beggiatoa, Thioploca, and Thiomargarita but also recently identified and relatively unknown candidate taxa, including "Candidatus Thiopilula" spp. and "Ca. Thiophysa" spp. We discovered a population of "Ca. Thiopilula" spp. colonizing cold seeps near Barbados at a ∼4.7-km water depth. The Barbados population consists of spherical cells that are morphologically similar to Thiomargarita spp., with elemental sulfur inclusions and a central vacuole, but have much smaller cell diameters (5 to 40 μm). Metatranscriptomic analysis revealed that when exposed to anoxic sulfidic conditions, Barbados "Ca. Thiopilula" organisms expressed genes for the oxidation of elemental sulfur and the reduction of nitrogenous compounds, consistent with their vacuolated morphology and intracellular sulfur storage capability. Metatranscriptomic analysis further revealed that anaerobic methane-oxidizing and sulfate-reducing organisms were active in the sediment, which likely provided reduced sulfur substrates for "Ca. Thiopilula" and other sulfur-oxidizing microorganisms in the community. The novel observations of "Ca. Thiopilula" and associated organisms reported here expand our knowledge of the globally distributed and ecologically successful Beggiatoaceae group and thus offer insight into the composition and ecology of deep cold seep microbial communities.

  4. Microbial Sulfate Reduction at Cold Seeps Based on Analysis of Carbonate Associated Sulfate

    NASA Astrophysics Data System (ADS)

    Feng, D.; Peng, Y.

    2014-12-01

    Microbial sulfate reduction and coupled anaerobic oxidation of methane (AOM) are the dominant biogeochemical processes occurring at cold seeps in marine settings. These processes not only support the growth of chemosynthetic communities but also promote the precipitation of authigenic carbonates. However, investigations of microbial sulfate reduction have been conducted only using porewaters or seep-related barites. The fact is that many seeps are either inactive or do not precipitate any barite minerals. Thus, little is known about the microbial sulfate reduction at these seep environments. The occurrence of authigenic carbonate has been documented at almost all cold seep sites, which provide a unique opportunity to investigate the microbial sulfate reduction using such carbonate. The presentation is focused on the concentrations and isotopic signatures of carbonate associated sulfate (CAS). The aim of the project is to determine the role of sulfate and sulfate reduction during carbonate precipitation at cold seeps. The CAS concentrations are 67-537 ppm in high-Mg calcite, 51-181 ppm in low-Mg calcite, and 116-565 in aragonite. The δ34SCAS and δ18OCAS also vary considerably, ranging from 21.9‰ to 56.2‰ (V-CDT) and from 10.1‰ to 24.8‰ (V-SMOW), respectively. On δ34SCAS versus δ18OCAS plots, both aragonite and calcite show linear trends that project down toward those of open seawater sulfate. The trends suggest that sulfate has been isotopically modified to various degrees in pore fluids before being incorporated into carbonate lattice. The much narrower δ34SCAS and δ18OCAS ranges for aragonite than for calcite suggests a much "pickier" condition for aragonite formation during early diagenesis. Our results suggest that concentration and isotopic composition of CAS in seep carbonates may be controlled by the supply of pore-water sulfate during carbonate precipitation. The reliability of CAS in carbonate of early diagenetic origin as a proxy of

  5. Lipid Biomarkers and Carbon Isotopic Composition from Authigenic Carbonates and Seep Sediments from the US Mid-Atlantic Margin

    NASA Astrophysics Data System (ADS)

    Campbell, P.; Prouty, N.; Demopoulos, A. W.; Roark, B.; Coykendall, K.

    2015-12-01

    Anaerobic oxidation of methane (AOM), mediated by Archaea and sulfate-reducing bacteria, is common in continental margin sediment and can result in authigenic carbonate precipitation. A lipid biomarker study was undertaken in Mid-Atlantic submarine canyons, focusing specifically on Baltimore and Norfolk canyons, to determine biomarker variability of carbonate rock and the associated sediment in cold seep communities dominated by chemosynthetic mussels, Bathymodiolus childressi. Preliminary 16S metagenomic results confirm the presence of free-living sulfur-reducing bacteria and methantrophic endosymbiotic bacteria in the mussels. Depleted d13C values in both the mussel tissue (-63 ‰) and authigenic carbonates (-48 ‰) support methanotrophy as the dominant nutritional pathway and AOM as the main driver of carbonate precipitation. In addition, paired 14C and 230Th dates are highly discordant, reflecting dilution of the 14C pool with fossil hydrocarbon derived carbon. Seep and canyon sediment, as well as authigenic carbonates, were collected and analyzed for a suite of biomarkers, including sterols, alcohols, alkanes and fatty acids, as well as δ13C values of select biomarkers, to elucidate pathways of organic matter cycling. A comparison of terrestrial biomarker signatures (e.g., n-alkane carbon preference index and C23 / (C23 + C29) values, HMW n-alkanes and C29 sterols) suggests that terrestrial inputs dominate the submarine canyon surface sediment, whereas seep sediment is predominantly marine autochthonous (i.e., cholesterol and 5α-cholestanol). Lipid biomarker profiles (e.g., n-alkanes in the C15 to C33 range) from authigenic carbonates mirror those found in the seep sediment, suggesting that the organisms mediating carbonate precipitation on the seafloor are characteristic of the assemblages present in the sediment at these sites. With widespread methane leakage recently discovered along the Atlantic Margin, the presence of AOM-mediated carbonate

  6. Characterisation of the Nematode Community of a Low-Activity Cold Seep in the Recently Ice-Shelf Free Larsen B Area, Eastern Antarctic Peninsula

    PubMed Central

    Hauquier, Freija; Ingels, Jeroen; Gutt, Julian; Raes, Maarten; Vanreusel, Ann

    2011-01-01

    Background Recent climate-induced ice-shelf disintegration in the Larsen A (1995) and B (2002) areas along the Eastern Antarctic Peninsula formed a unique opportunity to assess sub-ice-shelf benthic community structure and led to the discovery of unexplored habitats, including a low-activity methane seep beneath the former Larsen B ice shelf. Since both limited particle sedimentation under previously permanent ice coverage and reduced cold-seep activity are likely to influence benthic meiofauna communities, we characterised the nematode assemblage of this low-activity cold seep and compared it with other, now seasonally ice-free, Larsen A and B stations and other Antarctic shelf areas (Weddell Sea and Drake Passage), as well as cold-seep ecosystems world-wide. Principal Findings The nematode community at the Larsen B seep site differed significantly from other Antarctic sites in terms of dominant genera, diversity and abundance. Densities in the seep samples were high (>2000 individuals per 10 cm2) and showed below-surface maxima at a sediment depth of 2–3 cm in three out of four replicates. All samples were dominated by one species of the family Monhysteridae, which was identified as a Halomonhystera species that comprised between 80 and 86% of the total community. The combination of high densities, deeper density maxima and dominance of one species is shared by many cold-seep ecosystems world-wide and suggested a possible dependence upon a chemosynthetic food source. Yet stable 13C isotopic signals (ranging between −21.97±0.86‰ and −24.85±1.89‰) were indicative of a phytoplankton-derived food source. Conclusion The recent ice-shelf collapse and enhanced food input from surface phytoplankton blooms were responsible for the shift from oligotrophic pre-collapse conditions to a phytodetritus-based community with high densities and low diversity. The parthenogenetic reproduction of the highly dominant Halomonhystera species is rather unusual for marine

  7. Reproductive traits of the cold-seep symbiotic mussel Idas modiolaeformis: gametogenesis and larval biology.

    PubMed

    Marylène Gaudron, Sylvie; Demoyencourt, Emile; Duperron, Sébastien

    2012-02-01

    We describe the first reproductive features of a chemosynthetic mussel collected at cold seeps from the eastern Mediterranean Sea. Idas modiolaeformis (Bivalvia, Mytilidae) is a hermaphroditic species in which production of male and female gametes likely alternates, a feature regarded as an adaptation to patchy and ephemeral habitats. By using fluorescent in situ hybridization, we demonstrate that bacterial symbionts, while present within the gills, are absent within acini that enclose female gametes and male gametes. This supports the hypothesis of environmental acquisition of symbionts in chemosynthetic mytilids. Prodissoconch I (PI) is relatively small compared to prodissoconch II (PII), suggesting a planktotrophic larval stage. Diameters of the two larval shells are in the range of sizes reported for mytilids, with a PII size between that of the shallow Mytilus edulis and that of the cold-seep mussel "Bathymodiolus" childressi.

  8. Patterns and variability in geochemical signatures and microbial activity within and between diverse cold seep habitats along the lower continental slope, Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Bowles, Marshall; Hunter, Kimberley S.; Samarkin, Vladimir; Joye, Samantha

    2016-07-01

    We collected 69 sediment cores from distinct ecological and geological settings along the deep slope in the Northern Gulf of Mexico to evaluate whether specific geochemical- or habitat-related factors correlated with rates of microbial processes and geochemical signatures. By collecting replicate cores from distinct habitats across multiple sites, we illustrate and quantify the heterogeneity of cold seep geochemistry and microbial activity. These data also document the factors driving unique aspects of the geochemistry of deep slope gas, oil and brine seeps. Surprisingly little variation was observed between replicate (n=2-5) cores within sites for most analytes (except methane), implying that the common practice of collecting one core for geochemical analysis can capture the signature of a habitat in most cases. Depth-integrated concentrations of methane, dissolved inorganic carbon (DIC), and calcium were the predominant geochemical factors that correlated with a site's ecological or geological settings. Pore fluid methane concentration was related to the phosphate and DIC concentration, as well as to rates of sulfate reduction. While distinctions between seep habitats were identified from geochemical signatures, habitat specific geochemistry varied little across sites. The relative concentration of dissolved inorganic nitrogen versus phosphorus suggests that phosphorus availability limits biomass production at cold seeps. Correlations between calcium, chloride, and phosphate concentrations were indicative of brine-associated phosphate transport, suggesting that in addition to the co-migration of methane, dissolved organic carbon, and ammonium with brine, phosphate delivery is also associated with brine advection.

  9. Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano

    NASA Astrophysics Data System (ADS)

    Toki, Tomohiro; Higa, Ryosaku; Ijiri, Akira; Tsunogai, Urumu; Ashi, Juichiro

    2014-12-01

    We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in pore water extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ18OH2O and δDH2O values of the pore fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of pore fluids in the shallow sediments of the accretionary prism, which showed negative δ18OH2O and δDH2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, pore fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.

  10. Microbial Oxidation of Ethane within Seep Sediment at Coal Oil Point, Santa Barbara, CA

    NASA Astrophysics Data System (ADS)

    Mendes, S. D.; Duncombe, R.; Scarlett, R. D.; Shaffer, J.; Lensch, S.; Valentine, D. L.

    2013-12-01

    The hydrocarbon seep field at Coal Oil Point (COP), off the coast of Santa Barbara, California, releases more than 10^10 g of thermogenic natural gas each year. Only a fraction of this methane, ethane, propane, and butane reaches the atmosphere, and is instead consumed by marine microbes in both the sediment and water column. Bacterial respiration of these gases has been observed in aerobic and anaerobic conditions, with the exception of ethane (aerobic only) (Kniemeyer et. al 2007). This work seeks to quantify the rate of ethane oxidation (both aerobic and anaerobic) in marine sediment. A series of experiments, to be conducted using COP seep sediment aboard the R/V Atlantis in October 2013, will test how varying oxygen conditions impact ethane oxidation rate. Oxidation rates will be quantified using sensitive 3H-ethane tracers. Preliminary data from Shane's Seep, located within the COP seep field, indicates that ethane oxidation is restricted to the top 6 cm of sediment. This suggests that oxygen is a limiting factor, but further work is needed to establish if ethane oxidation is restricted to exclusively aerobic environments.

  11. Stable carbon, nitrogen and sulfur isotopes in non-carbonate fractions of cold-seep carbonates

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Peng, Yongbo; Peckmann, Jörn; Roberts, Harry; Chen, Duofu

    2017-04-01

    Sulfate-driven anaerobic oxidation of methane (AOM) supports chemosynthesis-based communities and limits the release of methane from marine sediments. This process promotes the formation of carbonates close to the seafloor along continental margins. The geochemical characteristics of the carbonate minerals of these rocks are increasingly understood, questions remain about the geochemical characteristics of the non-carbonate fractions. Here, we report stable carbon, nitrogen and sulfur isotope patterns in non-carbonate fractions of seep carbonates. The authigenic carbonates were collected from three modern seep provinces (Black Sea, Gulf of Mexico, and South China Sea) and three ancient seep deposits (Marmorito, northern Italy, Miocene; SR4 deposit of the Lincoln Creek Formation and Whiskey Creek, western Washington, USA, Eocene to Oligocene). The δ13C values of non-carbonate fractions range from ˜-25‰ to -80‰ VPDB. These values indicate that fossil methane mixed with varying amounts of pelagic organic matter is the dominant source of carbon in these fractions. The relatively small offset between the δ34S signatures of the non-carbonate fractions and the respective sulfide minerals suggests that locally produced hydrogen sulfide is the main source of sulfur in seep environments. The δ15N values of the non-carbonate fractions are generally lower than the corresponding values of deep-sea sediments, suggesting that organic nitrogen is mostly of a local origin. This study reveals the potential of using δ13C, δ15N, δ34S values to discern seep and non-seep deposits. In cases where δ13Ccarbonate values are only moderately low due to mixing processes and lipid biomarkers have been erased in the course of burial, it is difficult to trace back AOM owing to the lack of other records. This problem is even more pronounced when authigenic carbonate is not available in ancient seep environments. Acknowledgments: The authors thank BOEM and NOAA for their years' support

  12. Distribution and Geochemistry of Methane-Derived Cold Seep Carbonates Panoche, California

    NASA Astrophysics Data System (ADS)

    Csar, A. J.; Sample, J.

    2007-12-01

    Isolated authigenic carbonate concretions and pavements occur locally within fine grained siliciclastic rocks of the Tertiary Great Valley Sequence of western California. Outcrops in the Panoche and Tumey Hills region are a record of prolonged expulsion of methane- and H2S- rich fluids from a relict cold seep system at the sea floor of a paleo-forearc basin. The entire outcrop length of the seep horizons is at least 15 km along strike. Sandstone injectites underlie the main seep horizons and may have provided fluid pathways to the sea floor. The concretions found in this locality are commonly rounded and vertically elongate, up to 15 m in height and resembling pillars in current outcrop form. Discrete carbonate pavements crop out continuously for as much as 100 m, are generally less then 3 m thick, and lacking any discernable stratification. The entire surface expression of the cold seep carbonates follows along strike, as a series of discontinuous shale encased mounds. Faunal assemblages (tubeworms, bivalves, and textures suggestive of algal mats) are fossilized, commonly in living position, within the carbonate cements. Growth and cross cutting relations recorded in these carbonate cements provides a chronology of the geochemical evolution of fluid venting at the cold seep. The earliest cement phase typically encasing the fossils and sedimentary structures is generally a high magnesium, detritus rich, finely micritic calcite or protodolomite. Energy dispersive spectrometry indicates that these cements have Ca/Mg ratios ranging from 8:1 to nearly 1:1. Within this hosting matrix are commonly a series of circular or wavy planar precipitation bands indicating sequential cementation. These later cements tend to be low Mg calcite (Ca/Mg below 8:1) which precipitated into void spaces from edge to center as coarsely fibrous crystals as large as 1 mm in width and several mm long. Each of these cement types has evidence of multiple phases of dissolution and precipitation

  13. High-throughput transcriptome sequencing of the cold seep mussel Bathymodiolus platifrons.

    PubMed

    Wong, Yue Him; Sun, Jin; He, Li Sheng; Chen, Lian Guo; Qiu, Jian-Wen; Qian, Pei-Yuan

    2015-11-23

    Bathymodiolid mussels dominate hydrothermal vents, cold methane/sulfide-hydrocarbon seeps, and other sites of organic enrichment. Here, we aimed to explore the innate immune system and detoxification mechanism of the deep sea mussel Bathymodiolus platifrons collected from a methane seep in the South China Sea. We sequenced the transcriptome of the mussels' gill, foot and mantle tissues and generated a transcriptomic database containing 96,683 transcript sequences. Based on GO and KEGG annotations, we reported transcripts that were related to the innate immune system, heavy metal detoxification and sulfide metabolic genes. Our in-depth analysis on the isoforms of peptidoglycan recognition protein (PGRP) that have different cellular location and potentially differential selectivity towards peptidoglycan (PGN) from gram-positive and gram-negative bacteria were differentially expressed in different tissues. We also reported a potentially novel form of metallothionein and the production of phytochelatin in B. platifrons, which has not been reported in any of its coastal relative Mytilus mussel species. Overall, the present study provided new insights into heavy metal and sulfide metabolism in B. platifrons and can be served as the basis for future molecular studies on host-symbiont interactions in cold seep mussels.

  14. High-throughput transcriptome sequencing of the cold seep mussel Bathymodiolus platifrons

    PubMed Central

    Wong, Yue Him; Sun, Jin; He, Li Sheng; Chen, Lian Guo; Qiu, Jian-Wen; Qian, Pei-Yuan

    2015-01-01

    Bathymodiolid mussels dominate hydrothermal vents, cold methane/sulfide-hydrocarbon seeps, and other sites of organic enrichment. Here, we aimed to explore the innate immune system and detoxification mechanism of the deep sea mussel Bathymodiolus platifrons collected from a methane seep in the South China Sea. We sequenced the transcriptome of the mussels’ gill, foot and mantle tissues and generated a transcriptomic database containing 96,683 transcript sequences. Based on GO and KEGG annotations, we reported transcripts that were related to the innate immune system, heavy metal detoxification and sulfide metabolic genes. Our in-depth analysis on the isoforms of peptidoglycan recognition protein (PGRP) that have different cellular location and potentially differential selectivity towards peptidoglycan (PGN) from gram-positive and gram-negative bacteria were differentially expressed in different tissues. We also reported a potentially novel form of metallothionein and the production of phytochelatin in B. platifrons, which has not been reported in any of its coastal relative Mytilus mussel species. Overall, the present study provided new insights into heavy metal and sulfide metabolism in B. platifrons and can be served as the basis for future molecular studies on host-symbiont interactions in cold seep mussels. PMID:26593439

  15. Hypotaurine, N-methyltaurine, taurine, and glycine betaine as dominant osmolytes of vestimentiferan tubeworms from hydrothermal vents and cold seeps.

    PubMed

    Yin, M; Palmer, H R; Fyfe-Johnson, A L; Bedford, J J; Smith, R A; Yancey, P H

    2000-01-01

    Organic osmolytes, solutes that regulate cell volume, occur at high levels in marine invertebrates. These are mostly free amino acids such as taurine, which are "compatible" with cell macromolecules, and methylamines such as trimethylamine oxide, which may have a nonosmotic role as a protein stabilizer, and which is higher in many deep-sea animals. To better understand nonosmotic roles of osmolytes, we used high-performance liquid chromatography and (1)H-nuclear magnetic resonance (NMR) to analyze vestimentiferans (vestimentum tissue) from unusual marine habitats. Species from deep hydrothermal vents were Riftia pachyptila of the East Pacific Rise (2,636 m) and Ridgeia piscesae of the Juan de Fuca Ridge (2,200 m). Species from cold hydrocarbon seeps were Lamellibrachia sp. and an unnamed escarpid species from subtidal sediment seeps (540 m) off Louisiana and Lamellibrachia barhami from bathyal tectonic seeps (1,800-2,000 m) off Oregon. Riftia were dominated by hypotaurine (152 mmol/kg wet wt), an antioxidant, and an unidentified solute with an NMR spectrum consistent with a methylamine. Ridgeia were dominated by betaine (N-trimethylglycine; 109 mmol/kg), hypotaurine (64 mmol/kg), and taurine (61 mmol/kg). The escarpids were dominated by taurine (138 mmol/kg) and hypotaurine (69 mmol/kg). Both Lamellibrachia populations were dominated by N-methyltaurine (209-252 mmol/kg), not previously reported as a major osmolyte, which may be involved in methane and sulfate metabolism. Trunk and plume tissue of the Oregon Lamellibrachia were nearly identical to vestimentum in osmolyte composition. The methylamines may also stabilize proteins against pressure; they were significantly higher in the three deeper-dwelling groups.

  16. Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments.

    PubMed

    Bose, Arpita; Rogers, Daniel R; Adams, Melissa M; Joye, Samantha B; Girguis, Peter R

    2013-01-01

    Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2-C5) and longer alkanes. C2-C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1-C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the δ(13)C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5‰, respectively). The concurrent depletion in the δ(13)C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (-3.5 and -6.7‰ for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1-C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3-C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial community

  17. Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments

    PubMed Central

    Bose, Arpita; Rogers, Daniel R.; Adams, Melissa M.; Joye, Samantha B.; Girguis, Peter R.

    2013-01-01

    Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2–C5) and longer alkanes. C2–C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1–C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the δ13C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5‰, respectively). The concurrent depletion in the δ13C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (−3.5 and −6.7‰ for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1–C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3–C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial

  18. Petrology of a Jurassic cold seep carbonate mound, Great Valley Group, northern California

    SciTech Connect

    Campbell, K.A.; Bottjer, D.J. . Dept. of Geological Sciences)

    1992-01-01

    Ancient sites of chemosynthetic marine invertebrate communities have been increasingly described from the stratigraphic record. Fossil cold seeps are best identified by the stratigraphically restricted co-occurrence of anomalous carbonates and fossils of organisms that in modern environments are chemosymbiotic. A Late Jurassic (Tithonian) age fossil seep site is preserved in deep-water turbidites of the Stony Creek Formation (Great Valley Group). Two low-relief carbonate mounds contain an abundant and diverse fossil macrofauna including taxa whose modern counterparts are chemosymbiotic, as well as several associate taxa. Two broad carbonate fabric types are present: a bioturbated, peloidal, fossiliferous micrite with abundant flecks of organic matter and several wavy laminated marine cements. The micrite and cements are either irregularly interlayered on distinctly separated by corrosion surfaces coated with iron oxides that may mark pulses of H[sub 2]S-rich fluids to the seep. Petrographic observations indicate the following idealized paragenetic sequence: deposition of micrite, with contemporaneous biotic activity; corrosion event, with preferential preservation of some peloids; precipitation of pyrite on some corrosion surfaces and concentration of insoluble siltstone linings where corrosion has opened vugs; precipitation of blocky yellow calcite cement with organic-rich inclusions in void spaces and around peloids; growth of clear to gray, botryoidal to fibrous cement; and precipitation of late, clear calcite spar. Similar fabrics and abundant tube-like structures are present in another Great Valley carbonate lens of Early Cretaceous (Albian-Aptian) age exposed on the Cold Fork of Cottonwood Creek near Red Bluff, California. Detailed integration of petrological studies of these fabrics with stable isotope studies and fossil faunal distributions provide a powerful approach for understanding the history of development and individual fossil seeps.

  19. Biogeochemical signatures and microbial activity of different cold-seep habitats along the Gulf of Mexico deep slope

    NASA Astrophysics Data System (ADS)

    Joye, Samantha B.; Bowles, Marshall W.; Samarkin, Vladimir A.; Hunter, Kimberley S.; Niemann, Helge

    2010-11-01

    Microorganisms and the processes they mediate serve as the metabolic foundation of cold seeps. We characterized a suite of biogeochemical constituents and quantified rates of two key microbial processes, Sulfate Reduction (SR) and Anaerobic Oxidation of Methane (AOM), to assess variability between habitats at water depths exceeding 1000 m in the northern Gulf of Mexico. Rates of SR were highest in sediments beneath microbial mats, lower in brine-influenced and oil-influenced sediments, and lowest in animal habitats. Sediments collected near tubeworms had the highest SR rates for animal habitats. Rates of AOM generally were low, but higher rates were associated with brine-influenced, oil-influenced, tubeworm- and urchin-inhabited sediments. Rates of both SR and AOM were orders of magnitude lower at deep-slope sites compared to upper-slope sites examined previously. As observed at upper-slope sites, SR and AOM rates were often loosely coupled. At one site, AOM rates exceeded SR rates, suggesting that an alternate electron acceptor for AOM is possible. Extremely depleted δ13C values in methane illustrated the broad significance of biogenic methane production at deep-slope sites. Brine-influenced habitats were characterized by extremely high concentrations of ammonium and dissolved organic carbon, serving as important focused sources of these chemicals to adjacent environments.

  20. Stable isotopes provide new insights into vestimentiferan physiological ecology at Gulf of Mexico cold seeps.

    PubMed

    Becker, Erin Leigh; Macko, Stephen A; Lee, Raymond W; Fisher, Charles R

    2011-02-01

    On the otherwise low-biomass seafloor of the Gulf of Mexico (GoM) continental slope, natural oil and gas seeps are oases of local primary production that support lush animal communities. Hundreds of seep communities have been documented on the continental slope, and nutrition derived from seeps could be an important link in the overall GoM food web. Here, we present a uniquely large and cohesive data set of δ(13)C, δ(15)N, and δ(34)S compositions of the vestimentiferan tubeworms Escarpia laminata and Lamellibrachia sp. 1, which dominate biomass at GoM seeps and provide habitat for hundreds of other species. Our sampling design encompassed an entire region of the GoM lower slope, allowing us for the first time to assess spatial variability in isotope compositions and to robustly address long-standing hypotheses about how vestimentiferans acquire and cycle nutrients over their long lifespan (200+ years). Tissue δ(13)C values provided strong evidence that larger adult vestimentiferans use their buried roots to take up dissolved inorganic carbon from sediment pore water, while very small individuals use their plume to take up carbon dioxide from the seawater. δ(34)S values were extremely variable among individuals of the same species within one location (<1 m(2) area), indicating high variability in the inorganic sulfur pools on a very small spatial scale. This finding supports the hypothesis that vestimentiferans use their roots to cycle sulfate and sulfide between their symbionts and free-living consortia of sulfate-reducing archaea in the sediment. Finally, consistent differences in δ(15)N between two cooccurring vestimentiferan species provided the first strong evidence for partitioning of inorganic resources, which has significant implications for the ecology and evolution of this taxonomic group.

  1. Archaeal and anaerobic methane oxidizer communities in the Sonora Margin cold seeps, Guaymas Basin (Gulf of California).

    PubMed

    Vigneron, Adrien; Cruaud, Perrine; Pignet, Patricia; Caprais, Jean-Claude; Cambon-Bonavita, Marie-Anne; Godfroy, Anne; Toffin, Laurent

    2013-08-01

    Cold seeps, located along the Sonora Margin transform fault in the Guaymas Basin, were extensively explored during the 'BIG' cruise in June 2010. They present a seafloor mosaic pattern consisting of different faunal assemblages and microbial mats. To investigate this mostly unknown cold and hydrocarbon-rich environment, geochemical and microbiological surveys of the sediments underlying two microbial mats and a surrounding macrofaunal habitat were analyzed in detail. The geochemical measurements suggest biogenic methane production and local advective sulfate-rich fluxes in the sediments. The distributions of archaeal communities, particularly those involved in the methane cycle, were investigated at different depths (surface to 18 cm below the sea floor (cmbsf)) using complementary molecular approaches, such as Automated method of Ribosomal Intergenic Spacer Analysis (ARISA), 16S rRNA libraries, fluorescence in situ hybridization and quantitative polymerase chain reaction with new specific primer sets targeting methanogenic and anaerobic methanotrophic lineages. Molecular results indicate that metabolically active archaeal communities were dominated by known clades of anaerobic methane oxidizers (archaeal anaerobic methanotroph (ANME)-1, -2 and -3), including a novel 'ANME-2c Sonora' lineage. ANME-2c were found to be dominant, metabolically active and physically associated with syntrophic Bacteria in sulfate-rich shallow sediment layers. In contrast, ANME-1 were more prevalent in the deepest sediment samples and presented a versatile behavior in terms of syntrophic association, depending on the sulfate concentration. ANME-3 were concentrated in small aggregates without bacterial partners in a restricted sediment horizon below the first centimetres. These niche specificities and syntrophic behaviors, depending on biological surface assemblages and environmental availability of electron donors, acceptors and carbon substrates, suggest that ANME could support

  2. Archaeal and anaerobic methane oxidizer communities in the Sonora Margin cold seeps, Guaymas Basin (Gulf of California)

    PubMed Central

    Vigneron, Adrien; Cruaud, Perrine; Pignet, Patricia; Caprais, Jean-Claude; Cambon-Bonavita, Marie-Anne; Godfroy, Anne; Toffin, Laurent

    2013-01-01

    Cold seeps, located along the Sonora Margin transform fault in the Guaymas Basin, were extensively explored during the ‘BIG' cruise in June 2010. They present a seafloor mosaic pattern consisting of different faunal assemblages and microbial mats. To investigate this mostly unknown cold and hydrocarbon-rich environment, geochemical and microbiological surveys of the sediments underlying two microbial mats and a surrounding macrofaunal habitat were analyzed in detail. The geochemical measurements suggest biogenic methane production and local advective sulfate-rich fluxes in the sediments. The distributions of archaeal communities, particularly those involved in the methane cycle, were investigated at different depths (surface to 18 cm below the sea floor (cmbsf)) using complementary molecular approaches, such as Automated method of Ribosomal Intergenic Spacer Analysis (ARISA), 16S rRNA libraries, fluorescence in situ hybridization and quantitative polymerase chain reaction with new specific primer sets targeting methanogenic and anaerobic methanotrophic lineages. Molecular results indicate that metabolically active archaeal communities were dominated by known clades of anaerobic methane oxidizers (archaeal anaerobic methanotroph (ANME)-1, -2 and -3), including a novel ‘ANME-2c Sonora' lineage. ANME-2c were found to be dominant, metabolically active and physically associated with syntrophic Bacteria in sulfate-rich shallow sediment layers. In contrast, ANME-1 were more prevalent in the deepest sediment samples and presented a versatile behavior in terms of syntrophic association, depending on the sulfate concentration. ANME-3 were concentrated in small aggregates without bacterial partners in a restricted sediment horizon below the first centimetres. These niche specificities and syntrophic behaviors, depending on biological surface assemblages and environmental availability of electron donors, acceptors and carbon substrates, suggest that ANME could support

  3. Geochemical characteristics of the barite deposits at cold seeps from the northern Gulf of Mexico continental slope

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Roberts, Harry H.

    2011-09-01

    Although less common than the occurrence of authigenic carbonate, barite has been observed frequently at cold seeps on continental margins worldwide. It is understood that barite forms by the interaction of barium-rich and sulfate-free seeping fluids with dissolved sulfate of pore water near the seafloor, but questions remain about the geochemical processes and mode(s) of the barite formation. Here, we report geochemical characteristics of barite deposits at 11 cold seep locations from the northern Gulf of Mexico continental slope. Samples from these sites of fluid and gas expulsion provide environmental information on barite formation. Seafloor observations and samples acquired indicate that barites occur as chimneys, cones, crusts, irregular mound-like buildups up to 2-meters high, and as a material disseminated in host sediment. Most barite samples are white-to-gray and usually have a porous fabric and layered internal structure. Mineralogically, samples of barite may contain a significant amounts of carbonate minerals, such as calcite and dolomite, but aragonite is absent in all samples analyzed in this study. Negative δ 13C values (as low as - 46.4‰ V-PDB) of the associated carbonates strongly suggests that methane is the primary carbon source. The δ 34S and δ 18O values of the barites have large variations, ranging from 18‰ to 80.4‰ V-CDT, and 7.5‰ to 26.7‰ V-SMOW, respectively. On δ 34S versus δ 18O plots, many barite deposits show a linear trend that projects down toward the isotopic composition of seawater sulfate. The trend suggests that barite formed from seawater sulfate that has been isotopically modified to varying degrees by biological sulfate reduction. The δ 34S/δ 18O ratios vary between 2.4 and 4.1. The variations are interpreted to reflect local controls on the flux of barium-rich seep fluids, changes in the rate of bacterial sulfate reduction, and/or the openness of pore fluid system. The 87Sr/ 86Sr values of the barites

  4. Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps.

    PubMed

    Portail, Marie; Olu, Karine; Dubois, Stanislas F; Escobar-Briones, Elva; Gelinas, Yves; Menot, Lénaick; Sarrazin, Jozée

    In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the

  5. Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps

    PubMed Central

    Olu, Karine; Dubois, Stanislas F.; Escobar-Briones, Elva; Gelinas, Yves; Menot, Lénaick; Sarrazin, Jozée

    2016-01-01

    In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the

  6. Pervasive barite deposits at cold seeps from the northern Gulf of Mexico continental slope: Geochemical characteristics and formation mechanism

    NASA Astrophysics Data System (ADS)

    Feng, D.; Roberts, H. H.

    2010-12-01

    Although the formations of seep-related barite deposits are now known to form where Ba-rich fluids discharge at the seafloor, questions remain about the geochemical characteristics and consequently biogeochemical processes that control the formation of the barite. Knowledge of isotope fractionations accompanying microbial sulfate reduction is important because both sulfur and oxygen isotopes of barites have been used as indicator of the origin and geochemical history of the sulfate. However, studies that include both δ34S and δ18O of seep-related barites are rare and there is disagreement on the explanation of the data. Here, we present a comprehensive study of the barite deposits at 11 cold seeps from the northern Gulf of Mexico continental slope. Seafloor observations and samples acquired indicate that barites occur as chimneys, cones, crusts, irregular mound-like buildups up to meters high and as a material disseminated in host sediment. The white to gray barites usually show a porous fabric and layered internal structure. Mineralogically, samples of barite may contain a certain amount of carbonate minerals, such calcite, and dolomite, but aragonite is absent. Negative δ13C values (as low as -46.4‰ PDB) of the carbonates indicate that methane as primary carbon source. The δ34S and δ18O of the barites have a large variation, ranging from 18 to 80.4‰ CDT, and 7.5 to 26.7‰ SMOW. On δ34S versus δ18O patters, many barite deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trend suggests that barite is formed from seawater sulfate that has been isotopically modified to varying degrees by biological sulfate reduction. Both sulfur and oxygen isotope fractionations are controlled by kinetic isotope effects during microbial sulfate reduction, which is reflected by δ34S/δ18O ratios from different sites between 2.4 and 4.1. The variations primarily reflect local controls on the flux of Ba

  7. Diversity and distribution of eukaryotic microbes in and around a brine pool adjacent to the Thuwal cold seeps in the Red Sea.

    PubMed

    Wang, Yong; Zhang, Wei Peng; Cao, Hui Luo; Shek, Chun Shum; Tian, Ren Mao; Wong, Yue Him; Batang, Zenon; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2014-01-01

    A hypoxic/suboxic brine pool at a depth of about 850 m was discovered near the Thuwal cold seeps in the Red Sea. Filled with high concentrations of hydrogen sulfide and ammonia, such a brine pool might limit the spread of eukaryotic organisms. Here, we compared the communities of the eukaryotic microbes in a microbial mat, sediments and water samples distributed in 7 sites within and adjacent to the brine pool. Taxonomic classification of the pyrosequenced 18S rRNA amplicon reads showed that fungi highly similar to the species identified along the Arabic coast were almost ubiquitous in the water and sediment samples, supporting their wide distribution in various environments. The microbial mat displayed the highest species diversity and contained grazers and a considerable percentage of unclassified species. Phylogeny-based methods revealed novel lineages representing a majority of the reads from the interface between the sea water and brine pool. Phylogenetic relationships with more reference sequences suggest that the lineages were affiliated with novel Alveolata and Euglenozoa inhabiting the interface where chemosynthetic prokaryotes are highly proliferative due to the strong chemocline and halocline. The brine sediments harbored abundant species highly similar to invertebrate gregarine parasites identified in different oxygen-depleted sediments. Therefore, the present findings support the uniqueness of some microbial eukaryotic groups in this cold seep brine system.

  8. Diversity and distribution of eukaryotic microbes in and around a brine pool adjacent to the Thuwal cold seeps in the Red Sea

    PubMed Central

    Wang, Yong; Zhang, Wei Peng; Cao, Hui Luo; Shek, Chun Shum; Tian, Ren Mao; Wong, Yue Him; Batang, Zenon; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2014-01-01

    A hypoxic/suboxic brine pool at a depth of about 850 m was discovered near the Thuwal cold seeps in the Red Sea. Filled with high concentrations of hydrogen sulfide and ammonia, such a brine pool might limit the spread of eukaryotic organisms. Here, we compared the communities of the eukaryotic microbes in a microbial mat, sediments and water samples distributed in 7 sites within and adjacent to the brine pool. Taxonomic classification of the pyrosequenced 18S rRNA amplicon reads showed that fungi highly similar to the species identified along the Arabic coast were almost ubiquitous in the water and sediment samples, supporting their wide distribution in various environments. The microbial mat displayed the highest species diversity and contained grazers and a considerable percentage of unclassified species. Phylogeny-based methods revealed novel lineages representing a majority of the reads from the interface between the sea water and brine pool. Phylogenetic relationships with more reference sequences suggest that the lineages were affiliated with novel Alveolata and Euglenozoa inhabiting the interface where chemosynthetic prokaryotes are highly proliferative due to the strong chemocline and halocline. The brine sediments harbored abundant species highly similar to invertebrate gregarine parasites identified in different oxygen-depleted sediments. Therefore, the present findings support the uniqueness of some microbial eukaryotic groups in this cold seep brine system. PMID:24575081

  9. Comparative Composition, Diversity and Trophic Ecology of Sediment Macrofauna at Vents, Seeps and Organic Falls

    PubMed Central

    Bernardino, Angelo F.; Levin, Lisa A.; Thurber, Andrew R.; Smith, Craig R.

    2012-01-01

    Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities. PMID:22496753

  10. An evaluation of petrogenic hydrocarbons in northern Gulf of Alaska continental shelf sediments - The role of coastal oil seep inputs

    USGS Publications Warehouse

    Short, J.W.; Kolak, J.J.; Payne, J.R.; Van Kooten, G. K.

    2007-01-01

    We compared hydrocarbons in water, suspended particulate matter (SPM), and riparian sediment collected from coastal watersheds along the Yakataga foreland with corresponding hydrocarbons in Gulf of Alaska benthic sediments. This comparison allows an evaluation of hydrocarbon contributions to marine sediments from natural oil seeps, coal and organic matter (e.g., kerogen) associated with eroding siliciclastic rocks. The samples from oil seeps show extensive loss of low-molecular weight n-alkanes (sediment samples collected upstream from the oil seeps. After entering the fluvial systems, hydrocarbons from seep oils are rapidly diluted, and associate with the SPM phase as oil-mineral-aggregates (OMA). Johnston Creek, the watershed containing the most prolific seep, conveys detectable seep-derived hydrocarbons to the Gulf of Alaska, but overall seep inputs are largely attenuated by the (non-seep) petrogenic hydrocarbon content of the high SPM loads. In contrast to the geochemical signature of seep oil, Gulf of Alaska benthic sediments are characterized by abundant alkylated naphthalene homologues, relatively smooth n-alkane envelopes (n-C9 through n-C34, but with elevated levels of n-C27, n-C29, and n-C31), and small UCMs. Further, hydrocarbons in benthic sediments are highly intercorrelated. Taken together, these characteristics indicate that seep oil is a negligible petrogenic hydrocarbon source to the Gulf of Alaska continental shelf. Coaly material separated from the benthic sediment samples using a dense liquid (???2.00 g cm-3) also accounted for a minor portion of the total PAH (1-6%) and total n-alkanes (0.4-2%) in the benthic samples. Most of the hydrocarbon burden in the sediments is found in the denser sediment fraction and likely derives from organic matter contributed by denudation of siliciclastic formations in

  11. Food-web structure of seep sediment macrobenthos from the Gulf of Mexico

    USGS Publications Warehouse

    Demopoulos, Amanda W.J.; Gualtieri, Daniel; Kovacs, Kaitlin

    2010-01-01

    The slope environment of the Gulf of Mexico (GOM) supports dense communities of seep megafaunal invertebrates that rely on endosymbiotic bacteria for nutrition. Seep sediments also contain smaller macrofaunal invertebrates whose nutritional pathways are not well understood. Using stable-isotope analysis, we investigate the utilization of chemosynthetically fixed and methane-derived organic matter by macrofauna. Biological sampling was conducted in three lower-slope GOM seep environs: Green Canyon (GC852, 1428 m), Atwater Valley (AT340, 2230 m), and Alaminos Canyon (AC601, 2384 m). Infaunal delta13C and delta15N exhibited a broad range of values; most infauna appeared to be heterotrophic, although several taxa had very light delta15N and delta13C values, indicating possible reliance on chemoautotrophic symbioses. The lightest delta13C and delta15N values were observed in nematodes (delta13C=-54.6 + or - 0.1 per mil, delta15N=-6.1 + or - 0.2 per mil) and one gastropod (delta13C=-54.1 per mil, delta15N=-1.1 per mil) from Green Canyon. Mixing-model results indicated that sulfur-oxidizing Beggiatoa may be an important food source for seep infauna; the rate of utilization ranged from 60% to 100% at Green Canyon and Atwater Valley. The overall range in isotope values was similar across the three sites, suggesting that biogeochemical processes may be very similar in these geographically distinct areas.

  12. Food-web structure of seep sediment macrobenthos from the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Demopoulos, Amanda W. J.; Gualtieri, Daniel; Kovacs, Kaitlin

    2010-11-01

    The slope environment of the Gulf of Mexico (GOM) supports dense communities of seep megafaunal invertebrates that rely on endosymbiotic bacteria for nutrition. Seep sediments also contain smaller macrofaunal invertebrates whose nutritional pathways are not well understood. Using stable-isotope analysis, we investigate the utilization of chemosynthetically fixed and methane-derived organic matter by macrofauna. Biological sampling was conducted in three lower-slope GOM seep environs: Green Canyon (GC852, 1428 m), Atwater Valley (AT340, 2230 m), and Alaminos Canyon (AC601, 2384 m). Infaunal δ13C and δ15N exhibited a broad range of values; most infauna appeared to be heterotrophic, although several taxa had very light δ15N and δ13C values, indicating possible reliance on chemoautotrophic symbioses. The lightest δ13C and δ15N values were observed in nematodes (δ13C=-54.6±0.1‰, δ15N=-6.1±0.2‰) and one gastropod (δ13C=-54.1‰, δ15N=-1.1‰) from Green Canyon. Mixing-model results indicated that sulfur-oxidizing Beggiatoa may be an important food source for seep infauna; the rate of utilization ranged from 60% to 100% at Green Canyon and Atwater Valley. The overall range in isotope values was similar across the three sites, suggesting that biogeochemical processes may be very similar in these geographically distinct areas.

  13. Galatheid and chirostylid crustaceans (Decapoda: Anomura) from a cold seep environment in the northeastern South China Sea.

    PubMed

    Dong, Dong; Li, Xinzheng

    2015-12-09

    Six species of squat lobsters from a cold seep field in the northeastern South China Sea are studied. Two new species, Uroptychus jiaolongae n. sp. and U. spinulosus n. sp., are described, and their distinctions from the related species are detailed. Two species, Munidopsis tuberosa Osawa, Lin & Chan, 2008 and M. verrilli Benedict, 1902, are herein reported for the first time from a cold seep/hydrothermal vent environment. The number of squat lobsters species associated with those chemosynthetic environments now stands at forty-one.

  14. Environmental switching during biofilm development in a cold seep system and functional determinants of species sorting.

    PubMed

    Zhang, Weipeng; Tian, Renmao; Bo, Yang; Cao, Huiluo; Cai, Lin; Chen, Lianguo; Zhou, Guowei; Sun, Jin; Zhang, Xixiang; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2016-05-01

    The functional basis for species sorting theory remains elusive, especially for microbial community assembly in deep-sea environments. Using artificial surface-based biofilm models, our recent work revealed taxonomic succession during biofilm development in a newly defined cold seep system, the Thuwal cold seeps II, which comprises a brine pool and the adjacent normal bottom water (NBW) to form a metacommunity via the potential immigration of organisms from one patch to another. Here, we designed an experiment to investigate the effects of environmental switching between the brine pool and the NBW on biofilm assembly, which could reflect environmental filtering effects during bacterial immigration to new environments. Analyses of 16S rRNA genes of 71 biofilm samples suggested that the microbial composition of biofilms established in new environments was determined by both the source community and the incubation conditions. Moreover, a comparison of 18 metagenomes provided evidence for biofilm community assembly that was based primarily on functional features rather than taxonomic identities; metal ion resistance and amino acid metabolism were the major species sorting determinants for the succession of biofilm communities. Genome binning and pathway reconstruction of two bacterial species (Marinobacter sp. and Oleispira sp.) further demonstrated metal ion resistance and amino acid metabolism as functional traits conferring the survival of habitat generalists in both the brine pool and NBW. The results of this study shed new light on microbial community assembly in special habitats and bridge a gap in species sorting theory.

  15. On the relationship between methane production and oxidation by anaerobic methanotrophic communities from cold seeps of the Gulf of Mexico.

    PubMed

    Orcutt, Beth; Samarkin, Vladimir; Boetius, Antje; Joye, Samantha

    2008-05-01

    The anaerobic oxidation of methane (AOM) in the marine subsurface is a significant sink for methane in the environment, yet our understanding of its regulation and dynamics is still incomplete. Relatively few groups of microorganisms consume methane in subsurface environments--namely the anaerobic methanotrophic archaea (ANME clades 1, 2 and 3), which are phylogenetically related to methanogenic archaea. Anaerobic oxidation of methane presumably proceeds via a 'reversed' methanogenic pathway. The ANME are generally associated with sulfate-reducing bacteria (SRB) and sulfate is the only documented final electron acceptor for AOM in marine sediments. Our comparative study explored the coupling of AOM with sulfate reduction (SR) and methane generation (MOG) in microbial communities from Gulf of Mexico cold seep sediments that were naturally enriched with methane and other hydrocarbons. These sediments harbour a variety of ANME clades and SRB. Following enrichment under an atmosphere of methane, AOM fuelled 50-100% of SR, even in sediment slurries containing petroleum-associated hydrocarbons and organic matter. In the presence of methane and sulfate, the investigated microbial communities produce methane at a small fraction ( approximately 10%) of the AOM rate. Anaerobic oxidation of methane, MOG and SR rates decreased significantly with decreasing concentration of methane, and in the presence of the SR inhibitor molybdate, but reacted differently to the MOG inhibitor 2-bromoethanesulfonate (BES). The addition of acetate, a possible breakdown product of petroleum in situ and a potential intermediate in AOM/SR syntrophy, did not suppress AOM activity; rather acetate stimulated microbial activity in oily sediment slurries.

  16. In Situ Stable Isotopic Detection of Anaerobic Oxidation of Methane in Monterey Bay Cold Seeps Via Off-Axis Integrated Cavity Output Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Gupta, M.; Leen, J.; Provencal, R. A.; Parsotam, V.; Girguis, P. R.

    2010-12-01

    Anaerobic methane oxidation (AOM) plays an important role in global climate change by governing the release of methane from anoxic sediments into the global ocean and ultimately the atmosphere. Thus, gaining an accurate understanding of both the distribution of methane sources and the occurrence of AOM as well as the spatial and temporal variability of cycling pathways is critical. Environmental analyses of methane stable isotopic composition (δ13C-CH4) provide just such an indicator of methane source, whether biogenic or thermogenic, as well as a spatial and temporal integrator of microbial cycling pathways, such as AOM. Here we present results from several deployments of a newly developed in situ methane stable isotope analyzer capable of measuring δ13C-CH4 to full ocean depths. The instrument consisted of a miniaturized Off-Axis Integrated Cavity Output Spectroscopy (Off-Axis ICOS) analyzer housed in a cylindrical titanium pressure vessel for deep sea deployment. Dissolved gas was extracted from seawater using a Teflon AF diffusion membrane inlet. The instrument had an operating wavelength of 1647 nm and used chemometric spectral decomposition to determine the relative concentrations of 13CH4 and 12CH4 with a sensitivity of ± 0.2‰. Deployments to cold seep environments revealed a distinct separation in carbon isotopic composition between methane in advecting fluids as compared with methane from sediment pore fluids. During multiple visits to two different sites at Extrovert Cliff in Monterey Bay (960m), methane in advecting fluids ranged from -70.2‰ to -63.8‰. In contrast, methane-rich fluids sampled directly from pushcore holes taken through seep sediments contained methane with substantially higher δ13C values ranging from -64.2‰ to -50.2‰. These data implicate the influence of anaerobic oxidation of methane within these seep sediments. While the advective flux of methane to the seafloor from the central orifice of the seep is substantial, using

  17. When Organic-Rich Turbidites Reach 5000 m: "Cold-Seep Like" Life in the Congo Deep-Sea Fan

    NASA Astrophysics Data System (ADS)

    Pastor, L.; Toffin, L.; Cathalot, C.; Olu, K.; Brandily, C.; Bessette, S.; Lesongeur, F.; Godfroy, A.; Khripounoff, A.; Decker, C.; Taillefert, M.; Rabouille, C.

    2016-12-01

    The Congo canyon, located on the west coast of Africa, is a unique example of a canyon directly connected to a major river (The Congo River). Turbidites are responsible for a large input of terrestrial organic matter at depths up to 5000 m. These high inputs led to global high organic matter mineralization rates, with very localized hot spots that were visually observed and specifically sampled with a ROV. These hot spots, featuring substantial concentration of reduced compounds, mainly methane and sulfides, were recognizable in surface by the presence of reduced sediment patches, bacterial mats, and/or vesicomyid bivalves that host bacterial endosymbionts able to process H2S. In this paper we present geochemical sediment profiles of sulfate, methane, sulfide and dissolved iron together with phylogenetic diversity of 16S rRNA communities. This will give a first understanding of biogeochemical processes occurring in this peculiar ecosystem, mainly sulfate reduction, methanogenesis and subsequent anaerobic oxidation of methane with bacterial and archaeal assemblages similar to cold seeps environments. Iron also seems to play a major role in this system and iron/sulfur interactions as a sink for H2S can probably compete with H2S consumption by chemosynthetic bivalves, estimated at one site by vesicomyds gills incubations in a sulfide-rich solution.

  18. Benthic Community Structure and Sediment Geochemical Properties at Hydrocarbon Seeps Along the Continental Slope of the Western North Atlantic

    NASA Astrophysics Data System (ADS)

    Demopoulos, A. W.; Bourque, J. R.; Brooke, S.

    2015-12-01

    Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410-450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared

  19. Cold-seep habitat mapping: High-resolution spatial characterization of the Blake Ridge Diapir seep field

    NASA Astrophysics Data System (ADS)

    Wagner, Jamie K. S.; McEntee, Molly H.; Brothers, Laura L.; German, Christopher R.; Kaiser, Carl L.; Yoerger, Dana R.; Van Dover, Cindy Lee

    2013-08-01

    Relationships among seep community biomass, diversity, and physiographic controls such as underlying geology are not well understood. Previous efforts to constrain these relationships at the Blake Ridge Diapir were limited to observations from piloted deep-submergence vehicles. In August 2012, the autonomous underwater vehicle (AUV) Sentry collected geophysical and photographic data over a 0.131 km2 area at the Blake Ridge Diapir seeps. A nested survey approach was used that began with a regional or reconnaissance-style survey using sub-bottom mapping systems to locate and identify seeps and underlying conduits. This survey was followed by AUV-mounted sidescan sonar and multibeam echosounder systems mapping on a mesoscale to characterize the seabed physiography. At the most detailed survey level, digital photographic imaging was used to resolve sub-meter characteristics of the biology. Four pockmarks (25-70 m diameter) were documented, each supporting chemosynthetic communities. Concentric zonation of mussels and clams suggests the influence of chemical gradients on megafaunal distribution. Data collection and analytical techniques used here yield high-resolution habitat maps that can serve as baselines to constrain temporal evolution of seafloor seeps, and to inform ecological niche modeling and resource management.

  20. Cold-seep habitat mapping: high-resolution spatial characterization of the Blake Ridge Diapir seep field

    USGS Publications Warehouse

    Wagner, Jamie K.S.; McEntee, Molly H.; Brothers, Laura L.; German, Christopher R.; Kaiser, Carl L.; Yoerger, Dana R.; Van Dover, Cindy Lee

    2013-01-01

    Relationships among seep community biomass, diversity, and physiographic controls such as underlying geology are not well understood. Previous efforts to constrain these relationships at the Blake Ridge Diapir were limited to observations from piloted deep-submergence vehicles. In August 2012, the autonomous underwater vehicle (AUV) Sentry collected geophysical and photographic data over a 0.131 km2 area at the Blake Ridge Diapir seeps. A nested survey approach was used that began with a regional or reconnaissance-style survey using sub-bottom mapping systems to locate and identify seeps and underlying conduits. This survey was followed by AUV-mounted sidescan sonar and multibeam echosounder systems mapping on a mesoscale to characterize the seabed physiography. At the most detailed survey level, digital photographic imaging was used to resolve sub-meter characteristics of the biology. Four pockmarks (25–70 m diameter) were documented, each supporting chemosynthetic communities. Concentric zonation of mussels and clams suggests the influence of chemical gradients on megafaunal distribution. Data collection and analytical techniques used here yield high-resolution habitat maps that can serve as baselines to constrain temporal evolution of seafloor seeps, and to inform ecological niche modeling and resource management.

  1. In situ environment rather than substrate type dictates microbial community structure of biofilms in a cold seep system.

    PubMed

    Lee, On On; Wang, Yong; Tian, Renmao; Zhang, Weipeng; Shek, Chun Shum; Bougouffa, Salim; Al-Suwailem, Abdulaziz; Batang, Zenon B; Xu, Wei; Wang, Guang Chao; Zhang, Xixiang; Lafi, Feras F; Bajic, Vladmir B; Qian, Pei-Yuan

    2014-01-08

    Using microscopic and molecular techniques combined with computational analysis, this study examined the structure and composition of microbial communities in biofilms that formed on different artificial substrates in a brine pool and on a seep vent of a cold seep in the Red Sea to test our hypothesis that initiation of the biofilm formation and spreading mode of microbial structures differs between the cold seep and the other aquatic environments. Biofilms on different substrates at two deployment sites differed morphologically, with the vent biofilms having higher microbial abundance and better structural features than the pool biofilms. Microbes in the pool biofilms were more taxonomically diverse and mainly composed of various sulfate-reducing bacteria whereas the vent biofilms were exclusively dominated by sulfur-oxidizing Thiomicrospira. These results suggest that the redox environments at the deployment sites might have exerted a strong selection on microbes in the biofilms at two sites whereas the types of substrates had limited effects on the biofilm development.

  2. In situ environment rather than substrate type dictates microbial community structure of biofilms in a cold seep system

    NASA Astrophysics Data System (ADS)

    Lee, On On; Wang, Yong; Tian, Renmao; Zhang, Weipeng; Shek, Chun Shum; Bougouffa, Salim; Al-Suwailem, Abdulaziz; Batang, Zenon B.; Xu, Wei; Wang, Guang Chao; Zhang, Xixiang; Lafi, Feras F.; Bajic, Vladmir B.; Qian, Pei-Yuan

    2014-01-01

    Using microscopic and molecular techniques combined with computational analysis, this study examined the structure and composition of microbial communities in biofilms that formed on different artificial substrates in a brine pool and on a seep vent of a cold seep in the Red Sea to test our hypothesis that initiation of the biofilm formation and spreading mode of microbial structures differs between the cold seep and the other aquatic environments. Biofilms on different substrates at two deployment sites differed morphologically, with the vent biofilms having higher microbial abundance and better structural features than the pool biofilms. Microbes in the pool biofilms were more taxonomically diverse and mainly composed of various sulfate-reducing bacteria whereas the vent biofilms were exclusively dominated by sulfur-oxidizing Thiomicrospira. These results suggest that the redox environments at the deployment sites might have exerted a strong selection on microbes in the biofilms at two sites whereas the types of substrates had limited effects on the biofilm development.

  3. Community composition and temporal change at deep Gulf of Mexico cold seeps

    NASA Astrophysics Data System (ADS)

    Lessard-Pilon, Stephanie; Porter, Matthew D.; Cordes, Erik E.; MacDonald, Ian; Fisher, Charles R.

    2010-11-01

    Specialized cold-seep communities have been known to exist in the Gulf of Mexico (GOM) since the mid-1980s, but only recently has extensive research been carried out on sites at depths >1000 m. This study uses a combination of imagery and analyses within a Geographic Information Systems (GIS) framework to examine the composition of mussel and tubeworm communities at depths between 2200 and 2800 m in the Gulf of Mexico, spatial relations among the fauna, and changes in these communities over time. Photomosaics at three discrete seep communities were obtained in 2006 and a video mosaic of another community was obtained in 1992. Each of these communities was re-imaged in 2007. In addition, quantitative physical collections were made within two of the photomosaic sites and used to confirm the identification of megafauna, quantify the occurrence of smaller and cryptic macrofauna, and allow first-order calculations of biomass within the sites. Substrate type had a significant effect on community composition. Significant associations were identified between live mussels with anemones, shrimp, and sea cucumbers, and between tubeworm aggregations and Munidopsis sp. crabs and encrusting fauna, indicating differences in the composition of megafauna associated with adjacent mussel and tubeworm aggregations. Little change was seen in the total area colonized by foundation fauna (tubeworms and mussels) between years at any site. However, significant changes occurred in the positions of mussels, even over periods of a single year, at all sites, and evidence for the establishment of new tubeworm aggregations between 1992 and 2007 was noted at one site. These photomosaics provide data suggesting that environmental conditions can change over small spatial and temporal scales and mussels move in response to these changes. The successional trends are examined and compared to the patterns that have been documented in shallow (<1000-m depth) Gulf of Mexico seep communities.

  4. Methane fates in the benthos and water column at cold seep sites along the continental margin of Central and North America

    NASA Astrophysics Data System (ADS)

    Hansman, Roberta L.; Thurber, Andrew R.; Levin, Lisa A.; Aluwihare, Lihini I.

    2017-02-01

    The potential influence of methane seeps on carbon cycling is a key question for global assessments, but the study of carbon cycling in surface sediments and the water column of cold seep environments is complicated by the high temporal and spatial variability of fluid and gas fluxes at these sites. In this study we directly examined carbon sources supporting benthic and planktonic food webs at venting methane seeps using isotopic and molecular approaches that integrate this variability. At four seep environments located along North and Central America, microorganisms from two size fractions were collected over several days from 2800 to 9050 l of seawater to provide a time-integrated measure of key microbial groups and the carbon sources supporting the overall planktonic microbial community. In addition to water column measurements, the extent of seafloor methane release was estimated at two of the sites by examining the stable carbon isotopic signature (δ13C) of benthic metazoan infauna. This signature reveals carbon sources fueling the base of the food chain and thus provides a metric that represents a time-integrated view of the dominant microbial processes within the sediment. The stable carbon isotopic composition of microbial DNA (δ13C-DNA), which had values between -17.0 and -19.5‰, indicated that bulk planktonic microbial production was not ultimately linked to methane or other 13C-depleted seep-derived carbon sources. Instead these data support the importance of organic carbon derived from either photo- or chemoautotrophic CO2 fixation to the planktonic food web. Results of qPCR of microbial DNA sequences coding for a subunit of the particulate methane monooxygenase gene (pmoA) showed that only a small percentage of the planktonic microbial community were potential methane oxidizers possessing pmoA (<5% of 16S rRNA gene copies). There was an overall decrease of 13C-depleted carbon fueling the benthic metazoan community from 3 to 5 cm below the seafloor

  5. A big old cold seep revisited: the Paleocene Panoche-Tumey Hills system

    NASA Astrophysics Data System (ADS)

    Schwartz, H.; Sample, J.; Minisini, D.

    2007-12-01

    One of the largest ancient cold seeps known is exposed in the Panoche Hills and adjacent Tumey Hills, in central California. In outcrop the most striking components of the Panoche-Tumey Hills paleoseep (PTHP) are authigenic carbonate bodies representing methane-derived cementation at or just below the Paleocene seafloor, and sandstone injectites thought to delineate the subseafloor plumbing of the system. The carbonates and underlying injectites are largely contained and best displayed within the Moreno Formation, a dominantly shaley unit that was deposited at outer shelf depths on the western margin of the San Joaquin forearc basin in the Maastrichtian-Thanetian. Since our first (2002) publications about the PTHP we have learned a great deal about its scale and development. Field investigation has extended the length of the seep zone from an initial estimate of 5km to a minimum of 20km, beyond which the main seep horizon (the Cima Sandstone Lentil) is truncated by an unconformity. However, injectites lower in the Moreno Fm. persist for at least 100km along strike to the south, suggesting that the PTHP originally spanned much of the western margin of the Paleocene forearc. The stratigraphic range of the seep carbonates has also been revised upwards from 45m to at least 250m (representing approximately 3 my). The carbonates themselves have δ13C values between +3 and - 54‰ and δ18O values between -7 and +7‰(VPDB) and a range of habits, with irregular mounds and stratiform bodies volumetrically dominant. Mounds contain multiple fluid conduits, breccias, distinctive cement phases, and a zoned, low diversity chemotroph-rich paleofauna (including microbial mats, lucinid bivalves and vestimentiferan tubeworms). They represent focused, prolonged fluid flow, methane expulsion and ecosystem development, and are the best archives of individual seepage events. Stratiform bodies are uniformly micritic, laterally extensive and more biologically diverse. They represent

  6. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts. Copyright © 2012 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  7. Cold-seep mollusks are older than the general marine mollusk fauna.

    PubMed

    Kiel, Steffen; Little, Crispin T S

    2006-09-08

    The origin and possible antiquity of faunas at deep-sea hydrothermal vents and seeps have been debated since their discovery. We used the fossil record of seep mollusks to show that the living seep genera have significantly longer geologic ranges than the marine mollusks in general, but have ranges similar to those of deep-sea taxa, suggesting that seep faunas may be shaped by the factors that drive the evolution of life in the deep sea in general. Our data indicate that deep-sea anoxic/dysoxic events did not affect seep faunas, casting doubt on the suggested anoxic nature and/or global extent of these events.

  8. Cold-seep-driven carbonate deposits at the Central American forearc: contrasting evolution and timing in escarpment and mound settings

    NASA Astrophysics Data System (ADS)

    Liebetrau, V.; Augustin, N.; Kutterolf, S.; Schmidt, M.; Eisenhauer, A.; Garbe-Schönberg, D.; Weinrebe, W.

    2014-10-01

    Continuous surface cores of cold-seep carbonates were recovered offshore Pacific Nicaragua and Costa Rica from 800 to 1,500-m water depths (Meteor 66/3) in order to decipher their evolution and methane enriched fluid emanation in contrasting geological settings. Cores from the mounds Iguana, Perezoso, Baula V and from the Jaco Scarp escarpment were used for a multi-method approach. For both settings aragonite was revealed as dominant authigenic carbonate phase in vein fillings and matrix cementation, followed by Mg-calcite as second most abundant. This common precipitation process of CaCO3 polymorphs could be ascribed as indirectly driven by chemical changes of the advecting pore water due to anaerobic oxidation of methane. A more direct influence of seep-related microbial activity on the authigenic mineral assemblage in both settings is probably reflected by the observed minor amounts of dolomite and a dolomite-like CaMg carbonate (MgCO3 ~ 42 %). δ13C data of Jaco Scarp samples are significantly lower (-43 to -56 ‰ PDB) than for mound samples (-22 to -36 ‰ PDB), indicating differences in fluid composition and origin. Noteworthy, δ18O values of Scarp samples correlate most closely with the ocean signature at their time of formation. Documenting the archive potential, a high resolution case study of a mound core implies at least 40 changes in fluid supply within a time interval of approximately 14 ky. As most striking difference, the age data indicate a late-stage downward-progressing cementation front for all three mound cap structures (approx. 2-5 cm/ky), but a significantly faster upward carbonate buildup in the bulging sediments on top of the scarp environment (approx. 120 cm/ky). The latter data set leads to the hypothesis of chemoherm carbonate emplacement in accord with reported sedimentation rates until decompression of the advective fluid system, probably caused by the Jaco Scarp landslide and dating this to approximately 13,000 years ago.

  9. Identification of Methanogens and Controls on Methane Production in Incubations of Natural Methane Seep Sediments

    NASA Astrophysics Data System (ADS)

    Kevorkian, R.; Lloyd, K. G.

    2014-12-01

    Methane, the most abundant hydrocarbon in Earth's atmosphere, is produced in large quantities in sediments underlying the world's oceans. Very little of this methane makes it to surface sediments as it is consumed by Anaerobic Methanotrophs (ANME's) in consortia with Sulfate Reducing Bacteria (SRB). Less is known about which organisms are responsible for methane production in marine sediments, and whether that production is under thermodynamic control based on hydrogen concentrations. Although ANMEs have been found to be active in methanogenic sediments and incubations, it is currently unknown whether they are able to grow in methanogenic conditions. We demonstrated with bottle incubations of methane seep sediment taken from Cape Lookout Bight, NC, that hydrogen controls methane production. While sulfate was present the hydrogen concentration was maintained at below 2 nM. Only after the depletion of sulfate allowed hydrogen concentrations to rise above 5 nM did we see production of methane. The same sediments when spiked with methane gas demonstrated its complete removal while sulfate reduction occurred. Quantitative PCR shows that ANME-2 and ANME-1 increase in 16S copy number as methane increases. Total direct cell counts demonstrate a decline in cells with the decrease of sulfate until a recovery corresponding with production of methane. Our results strongly suggest that hydrogen concentrations influence what metabolic processes can occur in marine sediments, and that ANME-1 and ANME-2 are able to grow on the energy provided from methane production.

  10. Behavior of Carbonate Associated Sulfate During Authigenic Carbonates Precipitation at Cold Seeps

    NASA Astrophysics Data System (ADS)

    Feng, D.; Peng, Y.; Bao, H.; Roberts, H. H.

    2011-12-01

    The carbonate associated sulfate (CAS) has been widely used in investigating geochemistry of ancient seawater sulfate. The reliability of CAS as a proxy of contemporaneous seawater sulfate has been examined in multiple cases and the results have been somewhat assuring in most cases involving open ocean deposits. Many geological carbonate deposits, however, were the product of early diagenesis, the CAS behavior in them, especially among different carbonate mineral phases that are sensitive to microbial activity and pore-water chemistry have not been examined. Distinct mineral phases are occurring among modern cold-seep carbonates in the Gulf of Mexico, which provides us a unique opportunity to examine the relationship between mineral formation condition and the CAS within. We found that the CAS concentration in different minerals varies widely without a clear pattern. The δ34SCAS and δ18OCAS also vary considerably, ranging from 21.9% to 56.2% (V-CDT) and from 10.5% to 24.8% (V-SMOW), respectively. On δ34SCAS versus δ18OCAS plots, both aragonite and calcite show linear trends that project down toward those of open seawater sulfate. The trends suggest that sulfate has been isotopically modified to various degrees in pore fluids before being incorporated into carbonate lattice. The much narrower δ34SCAS and δ18OCAS ranges for aragonite than for calcite suggests a much "pickier" condition for aragonite formation during early diagenesis, which is consistent with the fact that aragonite is more prone to precipitate in high sulfate concentration environments. Our results suggest that concentration and isotopic composition of CAS in seep carbonates may be controlled by the supply of pore-water sulfate during carbonate precipitation. The reliability of CAS in carbonate of early diagenetic origin as a proxy of contemporaneous seawater sulfate is therefore questioned.

  11. Metatranscriptomic Analysis of Diminutive Thiomargarita-Like Bacteria (“Candidatus Thiopilula” spp.) from Abyssal Cold Seeps of the Barbados Accretionary Prism

    PubMed Central

    Flood, Beverly E.

    2015-01-01

    Large sulfur-oxidizing bacteria in the family Beggiatoaceae are important players in the global sulfur cycle. This group contains members of the well-known genera Beggiatoa, Thioploca, and Thiomargarita but also recently identified and relatively unknown candidate taxa, including “Candidatus Thiopilula” spp. and “Ca. Thiophysa” spp. We discovered a population of “Ca. Thiopilula” spp. colonizing cold seeps near Barbados at a ∼4.7-km water depth. The Barbados population consists of spherical cells that are morphologically similar to Thiomargarita spp., with elemental sulfur inclusions and a central vacuole, but have much smaller cell diameters (5 to 40 μm). Metatranscriptomic analysis revealed that when exposed to anoxic sulfidic conditions, Barbados “Ca. Thiopilula” organisms expressed genes for the oxidation of elemental sulfur and the reduction of nitrogenous compounds, consistent with their vacuolated morphology and intracellular sulfur storage capability. Metatranscriptomic analysis further revealed that anaerobic methane-oxidizing and sulfate-reducing organisms were active in the sediment, which likely provided reduced sulfur substrates for “Ca. Thiopilula” and other sulfur-oxidizing microorganisms in the community. The novel observations of “Ca. Thiopilula” and associated organisms reported here expand our knowledge of the globally distributed and ecologically successful Beggiatoaceae group and thus offer insight into the composition and ecology of deep cold seep microbial communities. PMID:25724961

  12. Interaction between hydrocarbon seepage, chemosynthetic communities and bottom water redox at cold seeps of the Makran accretionary prism: insights from habitat-specific pore water sampling and modeling

    NASA Astrophysics Data System (ADS)

    Fischer, D.; Sahling, H.; Nöthen, K.; Bohrmann, G.; Zabel, M.; Kasten, S.

    2011-09-01

    The interaction between fluid seepage, bottom water redox, and chemosynthetic communities was studied at cold seeps across one of the world's largest oxygen minimum zones (OMZ) located at the Makran convergent continental margin. Push cores were obtained from seeps within and at the lower boundary of the core-OMZ with a remotely operated vehicle. Extracted pore water was analyzed for sulfide and sulfate contents. Depending on oxygen availability, seeps were either colonized by microbial mats or by mats and macrofauna. The latter, including ampharetid polychaetes and vesicomyid clams, occurred in distinct benthic habitats which were arranged in a concentric fashion around gas orifices. At most sites colonized by microbial mats, hydrogen sulfide was exported into the bottom water. Where macrofauna was widely abundant, hydrogen sulfide was consumed within the sediment. Numerical modeling of pore water profiles was performed in order to assess rates of fluid advection and bioirrigation. While the magnitude of upward fluid flow decreased from 11 cm yr-1 to <1 cm yr-1 and the sulfate/methane transition zone (SMTZ) deepened with increasing distance from the central gas orifice, the fluxes of sulfate into the SMTZ did not significantly differ (6.6-9.3 mol m-2 yr-1). Depth-integrated rates of bioirrigation increased from 162 cm yr-1 in central habitats characterized by microbial mats and sparse macrofauna to 348 cm yr-1 in habitats of large and small vesicomyid clams. These results reveal that chemosynthetic macrofauna inhabiting the outer seep habitats at the lower boundary of the OMZ efficiently bioirrigate and thus transport sulfate into the upper 10 to 15 cm of the sediment. In this way bioirrigation compensates for the lower upward flux of methane in outer habitats and stimulates rates of anaerobic oxidation of methane (AOM) with sulfate high enough to provide sulfide for chemosynthesis. Through bioirrigation macrofauna engineer their geochemical environment and fuel

  13. Bedded Barite Deposits from Sonora (nw Mexico): a Paleozoic Analog for Modern Cold Seeps

    NASA Astrophysics Data System (ADS)

    Canet, C.; Anadón, P.; González-Partida, E.; Alfonso, P.; Rajabi, A.; Pérez-Segura, E.; Alba-Aldave, L. A.

    2013-05-01

    The Mazatán barite deposits represent an outstanding example of Paleozoic bedded barite, a poorly understood type of mineral deposit of major economic interest. The largest barite bodies of Mazatán are hosted within an Upper Carboniferous flysch succession, which formed part of an accretionary wedge related to the subduction of the Rheic Ocean beneath Gondwana. As well, a few barite occurrences are hosted in Upper Devonian, pre-orogenic turbidites. A variety of mineralized structures is displayed by barite, including: septaria nodules, enterolitic structures, rosettes and debris-flow conglomerates. Barite is accompanied by chalcedony, pyrite (framboids) and berthierine. Gas-rich fluid inclusions in barite were analyzed by Raman spectroscopy and methane was identified, suggesting the occurrence of light hydrocarbons in the environment within which barite precipitated. 13C-depleted carbonates (δ13C: -24.3 to -18.8‰) were found in the barite deposits; they formed through anaerobic oxidation of methane coupled to sulfate reduction, and yield negative δ18O values (-11.9 to -5.2‰) reflecting the isotopic composition of Devonian-Carboniferous seawater. Methane-derived carbonates occur in modern hydrocarbon seeps and have been reported from Mesozoic and Cenozoic seep sediments, but they have never before been described in Paleozoic bedded barite deposits. δ34S of barite varies from +17.6 to +64.1‰, with the lowest values overlapping the range for coeval seawater sulfate; this distribution indicates a process of sulfate reduction. Barite precipitation can be explained by mixing of methane- and barium-rich fluids with pore-water (seawater) containing sulfate residual from microbial reduction. Two analyses from barite gave an 87Sr/86Sr within and slightly above the range for seawater at the time of deposition, with 0.708130 and 0.708588, which would preclude the involvement of hydrothermal fluids in the mineralization process.

  14. A Peek at Fluid Flow in Monterey bay Cold Seeps Using Peepers

    NASA Astrophysics Data System (ADS)

    Plant, J. N.; Wheat, C. G.; Jannasch, H.

    2001-12-01

    The egress of pore water from the oceanic crust along plate boundaries includes pore water and bound volatiles from sediment as well as seawater that have interacted with basement rock. The chemical composition of these fluids is governed by complex water-rock interactions that are also a function of temperature and pressure. Several such sites of fluid seepage were located in Monterey Bay (USA), which has active strike-slip faulting and evidence for compression in the northern portion of the bay. Fluid and chemical fluxes were determined from these seeps to provide insights to the mechanisms for fluid release and the chemical conditions under which this fluid was altered. Systematic variations in pore water chemical and thermal data provide a measure of the composition of the fluid at depth, an estimate of the speed of upwelling, and an assessment of chemical reactions that alter the fluid as it ascends to the seafloor. Pore water chemical data, which were collected from in-situ extractors ("peepers") that provide for a contamination-free sample, and thermal data indicate maximum upwelling speeds of 1-5 cm/yr at most seeps, with the exception of Extrovert Cliff where upwelling speeds are as high as hundreds of m/yr. These fluids are the most altered fluids in the bay (units mmol/kg: S 12; SO4 0; Ca 16.4; Mg 28.4; K 6.0; Sr 0.35; Li 0.038; Alk 15; Cl 560). Elucidating environmental conditions under which fluids from each of the sites formed may ultimately permit us to constrain some of the variables controlling tectonic phenomena in Monterey Bay and along plate margins in general.

  15. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    NASA Astrophysics Data System (ADS)

    Guilini, Katja; Levin, Lisa A.; Vanreusel, Ann

    2012-04-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and δ13C evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity.

  16. Methane-carbon flow into the benthic food web at cold seeps--a case study from the Costa Rica subduction zone.

    PubMed

    Niemann, Helge; Linke, Peter; Knittel, Katrin; MacPherson, Enrique; Boetius, Antje; Brückmann, Warner; Larvik, Gaute; Wallmann, Klaus; Schacht, Ulrike; Omoregie, Enoma; Hilton, David; Brown, Kevin; Rehder, Gregor

    2013-01-01

    Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15∶0 and C17∶1ω6c with stable carbon isotope compositions as low as -53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab's nutrition. In addition, our lipid analyses also suggest that the crabs feed on other (13)C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus.

  17. Methane-Carbon Flow into the Benthic Food Web at Cold Seeps – A Case Study from the Costa Rica Subduction Zone

    PubMed Central

    Niemann, Helge; Linke, Peter; Knittel, Katrin; MacPherson, Enrique; Boetius, Antje; Brückmann, Warner; Larvik, Gaute; Wallmann, Klaus; Schacht, Ulrike; Omoregie, Enoma; Hilton, David; Brown, Kevin; Rehder, Gregor

    2013-01-01

    Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15∶0 and C17∶1ω6c with stable carbon isotope compositions as low as −53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab's nutrition. In addition, our lipid analyses also suggest that the crabs feed on other 13C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus. PMID:24116017

  18. A microbiological and biogeochemical investigation of the cold seep tubeworm Escarpia southwardae (Annelida: Siboglinidae): Symbiosis and trace element composition of the tube

    NASA Astrophysics Data System (ADS)

    Duperron, Sébastien; Gaudron, Sylvie M.; Lemaitre, Nolwenn; Bayon, Germain

    2014-08-01

    Tubeworms within the annelid family Siboglinidae rely on sulfur-oxidizing autotrophic bacterial symbionts for their nutrition, and are among the dominant metazoans occurring at deep-sea hydrocarbon seeps. Contrary to their relatives from hydrothermal vents, sulfide uptake for symbionts occurs within the anoxic subsurface sediment, in the posterior ‘root' region of the animal. This study reports on an integrated microbiological and geochemical investigation of the cold seep tubeworm Escarpia southwardae collected at the Regab pockmark (Gulf of Guinea). Our aim was to further constrain the links between the animal and its symbiotic bacteria, and their environment. We show that E. southwardae harbors abundant sulfur-oxidizing bacterial symbionts in its trophosome. Symbionts are able to fix inorganic carbon using the Calvin-Benson cycle, as reported in most other Siboglinidae, but can also use the reverse Tricarboxilic Acid Cycle. Surprisingly, the observed bacteria appear to be more closely related to symbionts of Escarpia and Lamellibrachia species from very distant sites located in the Gulf of Mexico and eastern Pacific, than to symbionts of a siboglinid occurring at a nearby methane seep site, only a few hundred km away from Regab. Then, by combining scanning electron microscopy and trace element (Mn, Fe, Sr, Zr) analyses of E. southwardae tube, we also show that two distinct oxidation fronts occur along the tube. The first one, near the posterior end of the tube, corresponds to the interface between oxic bottom waters and the underlying anoxic sediment. In contrast, the second redox front is located in the most anterior part of the tube, and could result from active oxygen uptake by the plume of the tubeworm. We speculate that intense oxygen consumption in this region could create favorable conditions for sulfate reduction by specialized bacteria associated with the plume, possibly leading to an additional source of dissolved sulfide that would further enhance

  19. Characteristics of vesicomyid clams and their environment at the Blake Ridge cold seep, South Carolina, USA

    USGS Publications Warehouse

    Heyl, Taylor P.; Gilhooly, William P.; Chambers, Randolph M.; Gilchrist, George W.; Macko, Stephen A.; Ruppel, Carolyn D.; Van Dover, Cindy L.

    2007-01-01

    Spatial distributions and patchiness of dominant megafaunal invertebrates in deep-sea seep environments may indicate heterogeneities in the flux of reduced chemical compounds. At the Blake Ridge seep off South Carolina, USA, the invertebrate assemblage includes dense populations of live vesicomyid clams (an undescribed species) as well as extensive clam shell beds (i.e. dead clams). In the present study, we characterized clam parameters (density, size-frequency distribution, reproductive condition) in relation to sulfur chemistry (sulfide and sulfate concentrations and isotopic compositions, pyrite and elemental sulfur concentrations) and other sedimentary metrics (grain size, organic content). For clams >5 mm, clam density was highest where the total dissolved sulfide concentration at 10 cm depth (ΣH2S10cm) was 0.4 to 1.1 mmol l–1; juvenile clams (2S10cm was lowest. Clams were reproductively capable across a broad range of ΣH2S10cm (0.1 to 6.4 mmol l–1), and females in the sampled populations displayed asynchronous gametogenesis. Sulfide concentrations in porewaters at the shell–sediment interface of cores from shell beds were high, 3.3 to 12.1 mmol l–1, compared to –1 sulfide concentrations at the clam–sediment interface in live clam beds. Concentration profiles for sulfide and sulfate in shell beds were typical of those expected where there is active microbial sulfate reduction. In clam beds, profiles of sulfide and sulfate concentrations were also consistent with rapid uptake of sulfide by the clams. Sulfate in shell beds was systematically enriched in 34S relative to that in clam beds due to microbial fractionation during sulfate reduction, but in clam beds, sulfate δ34S matched that of seawater (~20‰). Residual sulfide values in clam and shell beds were correspondingly depleted in 34S. Based on porewater sulfide concentrations in shell beds at the time of sampling, we suggest that clam mortality may have been due to an abrupt increase in

  20. A novel sister clade to the enterobacteria microviruses (family Microviridae) identified in methane seep sediments.

    PubMed

    Bryson, Samuel Joseph; Thurber, Andrew R; Correa, Adrienne M S; Orphan, Victoria J; Vega Thurber, Rebecca

    2015-10-01

    Methane seep microbial communities perform a key ecosystem service by consuming the greenhouse gas methane prior to its release into the hydrosphere, minimizing the impact of marine methane sources on our climate. Although previous studies have examined the ecology and biochemistry of these communities, none has examined viral assemblages associated with these habitats. We employed virus particle purification, genome amplification, pyrosequencing and gene/genome reconstruction and annotation on two metagenomic libraries, one prepared for ssDNA and the other for all DNA, to identify the viral community in a methane seep. Similarity analysis of these libraries (raw and assembled) revealed a community dominated by phages, with a significant proportion of similarities to the Microviridae family of ssDNA phages. We define these viruses as the Eel River Basin Microviridae (ERBM). Assembly and comparison of 21 ERBM closed circular genomes identified five as members of a novel sister clade to the Microvirus genus of Enterobacteria phages. Comparisons among other metagenomes and these Microviridae major-capsid sequences indicated that this clade of phages is currently unique to the Eel River Basin sediments. Given this ERBM clade's relationship to the Microviridae genus Microvirus, we define this sister clade as the candidate genus Pequeñovirus. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Genomic and Transcriptomic Evidence for Carbohydrate Consumption among Microorganisms in a Cold Seep Brine Pool.

    PubMed

    Zhang, Weipeng; Ding, Wei; Yang, Bo; Tian, Renmao; Gu, Shuo; Luo, Haiwei; Qian, Pei-Yuan

    2016-01-01

    The detailed lifestyle of microorganisms in deep-sea brine environments remains largely unexplored. Using a carefully calibrated genome binning approach, we reconstructed partial to nearly-complete genomes of 51 microorganisms in biofilms from the Thuwal cold seep brine pool of the Red Sea. The recovered metagenome-assembled genomes (MAGs) belong to six different phyla: Actinobacteria, Proteobacteria, Candidatus Cloacimonetes, Candidatus Marinimicrobia, Bathyarchaeota, and Thaumarchaeota. By comparison with close relatives of these microorganisms, we identified a number of unique genes associated with organic carbon metabolism and energy generation. These genes included various glycoside hydrolases, nitrate and sulfate reductases, putative bacterial microcompartment biosynthetic clusters (BMC), and F420H2 dehydrogenases. Phylogenetic analysis suggested that the acquisition of these genes probably occurred through horizontal gene transfer (HGT). Metatranscriptomics illustrated that glycoside hydrolases are among the most highly expressed genes. Our results suggest that the microbial inhabitants are well adapted to this brine environment, and anaerobic carbohydrate consumption mediated by glycoside hydrolases and electron transport systems (ETSs) is a dominant process performed by microorganisms from various phyla within this ecosystem.

  2. Correlative light/electron microscopy for the investigation of microbial mats from Black Sea Cold Seeps.

    PubMed

    Wrede, Christoph; Heller, Christina; Reitner, Joachim; Hoppert, Michael

    2008-05-01

    In several fields of cell biology, correlative microscopy is applied to compare the structure of objects at high resolution under the electron microscope with low resolution light microscopy images of the same sample. It is, however, difficult to prepare samples and marker systems that are applicable for both microscopic techniques for the same specimen at the same time. In our studies, we used microbial mats from Cold Seep communities for a simple and rapid correlative microscopy method. The mats consist of bacterial and archaeal microorganisms, coupling reverse methanogenesis to the reduction of sulfate. The reverse methanogenic pathway also generates carbonates that precipitate inside the mat and may be the main reason for the formation of a microbial reef. The mat shows highly differentiated aggregates of various organisms, tightly interconnected by extracellular polysaccharides. In order to investigate the role of EPS as adhesive mucilage for the biofilm and as a precipitation matrix for carbonate minerals, samples were embedded in a hydrophilic resin (Lowicryl K4 M). Sections were suitable for light as well as electron microscopy in combination with lectins, either labeled with a fluorescent marker or with colloidal gold. This allows lectin mapping at low resolution for light microscopy in direct comparison with a highly resolved electron microscopic image.

  3. Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system.

    PubMed

    Zhang, Wei Peng; Wang, Yong; Tian, Ren Mao; Bougouffa, Salim; Yang, Bo; Cao, Hui Luo; Zhang, Gen; Wong, Yue Him; Xu, Wei; Batang, Zenon; Al-Suwailem, Abdulaziz; Zhang, Xi Xiang; Qian, Pei-Yuan

    2014-10-17

    Studies focusing on biofilm assembly in deep-sea environments are rarely conducted. To examine the effects of substrate type on microbial community assembly, biofilms were developed on different substrates for different durations at two locations in the Red Sea: in a brine pool and in nearby bottom water (NBW) adjacent to the Thuwal cold seep II. The composition of the microbial communities in 51 biofilms and water samples were revealed by classification of pyrosequenced 16S rRNA gene amplicons. Together with the microscopic characteristics of the biofilms, the results indicate a stronger selection effect by the substrates on the microbial assembly in the brine pool compared with the NBW. Moreover, the selection effect by substrate type was stronger in the early stages compared with the later stages of the biofilm development. These results are consistent with the hypotheses proposed in the framework of species sorting theory, which states that the power of species sorting during microbial community assembly is dictated by habitat conditions, duration and the structure of the source community. Therefore, the results of this study shed light on the control strategy underlying biofilm-associated marine fouling and provide supporting evidence for ecological theories important for understanding the formation of deep-sea biofilms.

  4. Helium systematics of cold seep fluids at Monterey Bay, California, USA: Temporal variations and mantle contributions

    NASA Astrophysics Data System (ADS)

    Füri, E.; Hilton, D. R.; Brown, K. M.; Tryon, M. D.

    2009-08-01

    We report helium isotope ratios (3He/4He) as well as helium and neon abundance results for submarine cold seep fluids from Extrovert Cliff in Monterey Bay, California. Samples were collected in copper tubing attached to submarine flux meters operating in continuous pumping mode. Following instrumentation recovery, the tubing was sectioned to produce for the first time a high-resolution time series of dissolved He and Ne variations over a time span of several days. Noble gas concentrations are variable and appear affected by interaction with a hydrocarbon phase within the aquifer. However, it is still possible to resolve the He signal into components associated with air equilibration, excess air entrainment, and terrigenic fluxes (both crustal and mantle-derived). The mantle He contribution reaches ˜25-30% in some samples (up to 2.3 RA, where RA = air 3He/4He). Our quasi-continuous He-Ne record shows remarkable fluctuations over time scales of only a few hours and reflects the combined effects of gas stripping by hydrocarbons and an episodic input of mantle-derived fluids.

  5. Genomic and Transcriptomic Evidence for Carbohydrate Consumption among Microorganisms in a Cold Seep Brine Pool

    PubMed Central

    Zhang, Weipeng; Ding, Wei; Yang, Bo; Tian, Renmao; Gu, Shuo; Luo, Haiwei; Qian, Pei-Yuan

    2016-01-01

    The detailed lifestyle of microorganisms in deep-sea brine environments remains largely unexplored. Using a carefully calibrated genome binning approach, we reconstructed partial to nearly-complete genomes of 51 microorganisms in biofilms from the Thuwal cold seep brine pool of the Red Sea. The recovered metagenome-assembled genomes (MAGs) belong to six different phyla: Actinobacteria, Proteobacteria, Candidatus Cloacimonetes, Candidatus Marinimicrobia, Bathyarchaeota, and Thaumarchaeota. By comparison with close relatives of these microorganisms, we identified a number of unique genes associated with organic carbon metabolism and energy generation. These genes included various glycoside hydrolases, nitrate and sulfate reductases, putative bacterial microcompartment biosynthetic clusters (BMC), and F420H2 dehydrogenases. Phylogenetic analysis suggested that the acquisition of these genes probably occurred through horizontal gene transfer (HGT). Metatranscriptomics illustrated that glycoside hydrolases are among the most highly expressed genes. Our results suggest that the microbial inhabitants are well adapted to this brine environment, and anaerobic carbohydrate consumption mediated by glycoside hydrolases and electron transport systems (ETSs) is a dominant process performed by microorganisms from various phyla within this ecosystem. PMID:27895636

  6. Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system

    PubMed Central

    Zhang, Wei Peng; Wang, Yong; Tian, Ren Mao; Bougouffa, Salim; Yang, Bo; Cao, Hui Luo; Zhang, Gen; Wong, Yue Him; Xu, Wei; Batang, Zenon; Al-Suwailem, Abdulaziz; Zhang, Xi Xiang; Qian, Pei-Yuan

    2014-01-01

    Studies focusing on biofilm assembly in deep-sea environments are rarely conducted. To examine the effects of substrate type on microbial community assembly, biofilms were developed on different substrates for different durations at two locations in the Red Sea: in a brine pool and in nearby bottom water (NBW) adjacent to the Thuwal cold seep II. The composition of the microbial communities in 51 biofilms and water samples were revealed by classification of pyrosequenced 16S rRNA gene amplicons. Together with the microscopic characteristics of the biofilms, the results indicate a stronger selection effect by the substrates on the microbial assembly in the brine pool compared with the NBW. Moreover, the selection effect by substrate type was stronger in the early stages compared with the later stages of the biofilm development. These results are consistent with the hypotheses proposed in the framework of species sorting theory, which states that the power of species sorting during microbial community assembly is dictated by habitat conditions, duration and the structure of the source community. Therefore, the results of this study shed light on the control strategy underlying biofilm-associated marine fouling and provide supporting evidence for ecological theories important for understanding the formation of deep-sea biofilms. PMID:25323200

  7. A metagenomic study of methanotrophic microorganisms in Coal Oil Point seep sediments

    PubMed Central

    2011-01-01

    Background Methane oxidizing prokaryotes in marine sediments are believed to function as a methane filter reducing the oceanic contribution to the global methane emission. In the anoxic parts of the sediments, oxidation of methane is accomplished by anaerobic methanotrophic archaea (ANME) living in syntrophy with sulphate reducing bacteria. This anaerobic oxidation of methane is assumed to be a coupling of reversed methanogenesis and dissimilatory sulphate reduction. Where oxygen is available aerobic methanotrophs take part in methane oxidation. In this study, we used metagenomics to characterize the taxonomic and metabolic potential for methane oxidation at the Tonya seep in the Coal Oil Point area, California. Two metagenomes from different sediment depth horizons (0-4 cm and 10-15 cm below sea floor) were sequenced by 454 technology. The metagenomes were analysed to characterize the distribution of aerobic and anaerobic methanotrophic taxa at the two sediment depths. To gain insight into the metabolic potential the metagenomes were searched for marker genes associated with methane oxidation. Results Blast searches followed by taxonomic binning in MEGAN revealed aerobic methanotrophs of the genus Methylococcus to be overrepresented in the 0-4 cm metagenome compared to the 10-15 cm metagenome. In the 10-15 cm metagenome, ANME of the ANME-1 clade, were identified as the most abundant methanotrophic taxon with 8.6% of the reads. Searches for particulate methane monooxygenase (pmoA) and methyl-coenzyme M reductase (mcrA), marker genes for aerobic and anaerobic oxidation of methane respectively, identified pmoA in the 0-4 cm metagenome as Methylococcaceae related. The mcrA reads from the 10-15 cm horizon were all classified as originating from the ANME-1 clade. Conclusions Most of the taxa detected were present in both metagenomes and differences in community structure and corresponding metabolic potential between the two samples were mainly due to abundance

  8. A metagenomic study of methanotrophic microorganisms in Coal Oil Point seep sediments.

    PubMed

    Håvelsrud, Othilde Elise; Haverkamp, Thomas H A; Kristensen, Tom; Jakobsen, Kjetill S; Rike, Anne Gunn

    2011-10-04

    Methane oxidizing prokaryotes in marine sediments are believed to function as a methane filter reducing the oceanic contribution to the global methane emission. In the anoxic parts of the sediments, oxidation of methane is accomplished by anaerobic methanotrophic archaea (ANME) living in syntrophy with sulphate reducing bacteria. This anaerobic oxidation of methane is assumed to be a coupling of reversed methanogenesis and dissimilatory sulphate reduction. Where oxygen is available aerobic methanotrophs take part in methane oxidation. In this study, we used metagenomics to characterize the taxonomic and metabolic potential for methane oxidation at the Tonya seep in the Coal Oil Point area, California. Two metagenomes from different sediment depth horizons (0-4 cm and 10-15 cm below sea floor) were sequenced by 454 technology. The metagenomes were analysed to characterize the distribution of aerobic and anaerobic methanotrophic taxa at the two sediment depths. To gain insight into the metabolic potential the metagenomes were searched for marker genes associated with methane oxidation. Blast searches followed by taxonomic binning in MEGAN revealed aerobic methanotrophs of the genus Methylococcus to be overrepresented in the 0-4 cm metagenome compared to the 10-15 cm metagenome. In the 10-15 cm metagenome, ANME of the ANME-1 clade, were identified as the most abundant methanotrophic taxon with 8.6% of the reads. Searches for particulate methane monooxygenase (pmoA) and methyl-coenzyme M reductase (mcrA), marker genes for aerobic and anaerobic oxidation of methane respectively, identified pmoA in the 0-4 cm metagenome as Methylococcaceae related. The mcrA reads from the 10-15 cm horizon were all classified as originating from the ANME-1 clade. Most of the taxa detected were present in both metagenomes and differences in community structure and corresponding metabolic potential between the two samples were mainly due to abundance differences. The results suggests that

  9. In situ environment rather than substrate type dictates microbial community structure of biofilms in a cold seep system

    PubMed Central

    Lee, On On; Wang, Yong; Tian, Renmao; Zhang, Weipeng; Shek, Chun Shum; Bougouffa, Salim; Al-Suwailem, Abdulaziz; Batang, Zenon B.; Xu, Wei; Wang, Guang Chao; Zhang, Xixiang; Lafi, Feras F.; Bajic, Vladmir B.; Qian, Pei-Yuan

    2014-01-01

    Using microscopic and molecular techniques combined with computational analysis, this study examined the structure and composition of microbial communities in biofilms that formed on different artificial substrates in a brine pool and on a seep vent of a cold seep in the Red Sea to test our hypothesis that initiation of the biofilm formation and spreading mode of microbial structures differs between the cold seep and the other aquatic environments. Biofilms on different substrates at two deployment sites differed morphologically, with the vent biofilms having higher microbial abundance and better structural features than the pool biofilms. Microbes in the pool biofilms were more taxonomically diverse and mainly composed of various sulfate-reducing bacteria whereas the vent biofilms were exclusively dominated by sulfur-oxidizing Thiomicrospira. These results suggest that the redox environments at the deployment sites might have exerted a strong selection on microbes in the biofilms at two sites whereas the types of substrates had limited effects on the biofilm development. PMID:24399144

  10. Unexpected co-occurrence of six bacterial symbionts in the gills of the cold seep mussel Idas sp. (Bivalvia: Mytilidae).

    PubMed

    Duperron, Sébastien; Halary, Sébastien; Lorion, Julien; Sibuet, Myriam; Gaill, Françoise

    2008-02-01

    Bathymodioline mussels occur in chemosynthesis-based ecosystems such as cold seeps, hydrothermal vents and organic debris worldwide. Their key adaptation to these environments is their association with bacterial endosymbionts which ensure a chemosynthetic primary production based on the oxidation of reduced compounds such as methane and sulfide. We herein report a multiple symbiosis involving six distinct bacterial 16S rRNA phylotypes, including two belonging to groups not yet reported as symbionts in mytilids, in a small Idas mussel found on carbonate crusts in a cold seep area located north to the Nile deep-sea fan (Eastern Mediterranean). Symbionts co-occur within hosts bacteriocytes based on fluorescence in situ hybridizations, and sequencing of functional genes suggests they have the potential to perform autotrophy, and sulfide and methane oxidation. Previous studies indicated the presence of only one or two symbiont 16S rRNA phylotypes in bathymodioline mussels. Together with the recent discovery of four bacterial symbionts in the large seep species Bathymodiolus heckerae, this study shows that symbiont diversity has probably been underestimated, and questions whether the common ancestor of bathymodioline mussels was associated with multiple bacteria.

  11. Depth-related structure and ecological significance of cold-seep communities—a case study from the Sea of Okhotsk

    NASA Astrophysics Data System (ADS)

    Sahling, Heiko; Galkin, Sergey V.; Salyuk, Anatoly; Greinert, Jens; Foerstel, Hilmar; Piepenburg, Dieter; Suess, Erwin

    2003-12-01

    We discovered and investigated several cold-seep sites in four depth zones of the Sea of Okhotsk off Northeast Sakhalin: outer shelf (160-250 m), upper slope (250-450 m), intermediate slope (450-800 m), and Derugin Basin (1450-1600 m). Active seepage of free methane or methane-rich fluids was detected in each zone. However, seabed photography and sampling revealed that the number of chemoautotrophic species decreases dramatically with decreasing water depth. At greatest depths in the Derugin Basin, the seeps were inhabited by bacterial mats and bivalves of the families Vesicomyidae ( Calyptogena aff. pacifica, C. rectimargo, Archivesica sp.), Solemyidae ( Acharax sp.) and Thyasiridae ( Conchocele bisecta). In addition, pogonophoran tubeworms of the family Sclerolinidae were found in barite edifices. At the shallowest sites, on the shelf at 160 m, the seeps lack chemoautotrophic macrofauna; their locations were indicated only by the patchy occurrence of bacterial mats. Typical seep-endemic metazoans with chemosynthetic symbionts were confined to seep sites at depths below 370 m. A comparative analysis of the structure of seep and background communities suggests that differences in predation pressure may be an important determinant of this pattern. The abundance of predators such as carnivorous brachyurans and asteroids, which can invade seeps from adjacent habitats and efficiently prey on sessile seep bivalves, decreased very pronouncedly with depth. We conclude from the obvious correlation with the conspicuous pattern in the distribution of seep assemblages that, on the shelf and at the upper slope, predator pressure may be high enough to effectively impede any successful settlement of viable populations of seep-endemic metazoans. However, there was also evidence that other depth-related factors, such as bottom-water current, sedimentary regimes, oxygen concentrations and the supply of suitable settling substrates, may additionally regulate the distribution of seep

  12. Coupled LBM-DEM Three-phase Simulation on Gas Flux Seeping from Marine Sediment

    NASA Astrophysics Data System (ADS)

    Kano, Y.; Sato, T.

    2014-12-01

    One of the main issues of the geological storage of CO2 under the seabed is a risk of CO2 leakage. Once CO2seeps into the ocean, it rises in water column dissolving into seawater, which results in the acidification of seawater and/or returning to the air. Its behaviour significantly depends on flow rate and bubble size (Kano et al., 2009; Dewar et al., 2013). As for porous media, bubble size is generally predicted through simple force balance based on flow rate, surface tension and channel size which is estimated by porosity and grain size. However, in shallow marine sediments, grains could be mobilised and displaced by buoyant gas flow, which causes distinctive phenomena such as blow-out or formation of gas flow conduit. As a result, effective gas flux into seawater can be intermissive, and/or concentrated in narrow area (QICS, 2012; Kawada, 2013). Bubble size is also affected by these phenomena. To predict effective gas flux and bubble size into seawater, three-phase behaviour of gas-water-sediment grains should be revealed. In this presentation, we will report the results of gas-liquid-solid three-phase simulations and their comparisons with experimental and observation data. Size of solid particles is based on grain size composing marine sediments at some CCS project sites. Fluid-particle interactions are solved using the lattice Boltzmann method (LBM), while the particle-particle interactions are treated by coupling with the Discrete Element method (DEM). References: Dewar, M., Wei, W., McNeil, D., Chen, B., 2013. Small-scale modelling of the physiochemical impacts of CO2leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters. Marine Pollution Bulletin 73(2), 504-515. Kano, Y., Sato, T., Kita, J., Hirabayashi, S., Tabeta, S., 2009. Model prediction on the rise of pCO2 in uniform flows by leakage of CO2purposefully stored under the seabed. Int. J. Greenhouse Gas Control, Vol. 3(5), 617-625. Kawada, R. 2014. A study on the

  13. Transovarial inheritance of endosymbiotic bacteria in clams inhabiting deep-sea hydrothermal vents and cold seeps.

    PubMed Central

    Cary, S C; Giovannoni, S J

    1993-01-01

    Vesicomyid clams are conspicuous fauna at many deep-sea hydrothermal-vent and cold-seep habitats. All species examined have specialized gill tissue harboring endosymbiotic bacteria, which are thought to provide the hosts' sole nutritional support. In these species mechanisms of symbiont inheritance are likely to be key elements of dispersal strategies. These mechanisms have remained unresolved because the early life stages are not available for developmental studies. A specific 16S rRNA-directed oligodeoxynucleotide probe (CG1255R) for the vesocomyid endosymbionts was used in a combination of sensitive hybridization techniques to detect and localize the endosymbionts in host germ tissues. Symbiont-specific polymerase chain reaction amplifications, comparative gene sequencing, and restriction fragment length polymorphisms were used to detect and confirm the presence of symbiont target in tissue nucleic acid extracts. Nonradioactive in situ hybridizations were used to resolve the position of the bacterial endosymbionts in host cells. Symbiont 16S rRNA genes were consistently amplified from the ovarial tissue of three species of vesicomyid clams: Calyptogena magnifica, C. phaseoliformis, and C. pacifica. The nucleotide sequences of the genes amplified from ovaries were identical to those from the respective host symbionts. In situ hybridizations to CG1255R labeled with digoxigenin-11-dUTP were performed on ovarial tissue from each of the vesicomyid clams. Detection of hybrids localized the symbionts to follicle cells surrounding the primary oocytes. These results suggest that vesicomyid clams assure successful, host-specific inoculation of all progeny by using a transovarial mechanism of symbiont transmission. Images Fig. 1 Fig. 2 Fig. 3 PMID:8100068

  14. Miocene shallow-marine cold seep carbonate in fold-and-thrust Western Foothills, SW Taiwan

    NASA Astrophysics Data System (ADS)

    Chien, Chih-Wei; Huang, Chi-Yue; Chen, Zhong; Lee, Horng-Chun; Harris, Ron

    2012-08-01

    A mound-shaped authigenic carbonate buildup (50 m wide and 5 m high) occurred in the middle part of the Late Miocene shallow marine succession (the Hunghuatzu Formation) exposed along the Nantzuhsien River, SW Taiwan. The carbonate concretions are classified into four types based on morphology, which appeared to develop in upward sequence with vague boundaries: (1) flat-pipe shaped nodules: highly dolomitic small pipes or nodules subparallel to the host strata, (2) bulb-shaped nodules: discrete or combined small mesoclots with subspherical to irregular shapes, (3) mushroom-shaped concretions: large mushroom-like or irregular shaped blocks with chimney or vent structures, and (4) carbonated layers with sedimentary structures. These concretions are mainly composed of dolomite micrites, quartz, feldspar, muscovite, and clay minerals, ubiquitously interweaved with blackish brown colored low magnesium calcite (LMC) veins. Low δ13CVPDB values (-51.8‰ to -29.8‰) of all types of the carbonates reveal that the carbonates were mainly derived from anaerobic oxidation of hydrocarbons. Many samples are also 18O-depleted (δ18OVPDB: -11.5‰ to 1.00‰) due to the mixture with isotopically light LMC veins, likely precipitated from meteoric waters. There are numerous chemosymbiotic bivalve fossils (genus Monitilora? diameter 3-4 cm) in growth position just above the carbonate buildup. According to the geological and isotopic signatures, the Hunghuatzu carbonates are related to a cold seep pseudobioherm, which formed in a very shallow marine environment like tidal-flat in a passive margin setting. Exposures of the Hunghuatzu pseudobioherm may provide clues for tracking and comparing the evolution history of gas reservoir systems and hints of active tectonics of the SW Taiwan region.

  15. Transovarial inheritance of endosymbiotic bacteria in clams inhabiting deep-sea hydrothermal vents and cold seeps.

    PubMed

    Cary, S C; Giovannoni, S J

    1993-06-15

    Vesicomyid clams are conspicuous fauna at many deep-sea hydrothermal-vent and cold-seep habitats. All species examined have specialized gill tissue harboring endosymbiotic bacteria, which are thought to provide the hosts' sole nutritional support. In these species mechanisms of symbiont inheritance are likely to be key elements of dispersal strategies. These mechanisms have remained unresolved because the early life stages are not available for developmental studies. A specific 16S rRNA-directed oligodeoxynucleotide probe (CG1255R) for the vesocomyid endosymbionts was used in a combination of sensitive hybridization techniques to detect and localize the endosymbionts in host germ tissues. Symbiont-specific polymerase chain reaction amplifications, comparative gene sequencing, and restriction fragment length polymorphisms were used to detect and confirm the presence of symbiont target in tissue nucleic acid extracts. Nonradioactive in situ hybridizations were used to resolve the position of the bacterial endosymbionts in host cells. Symbiont 16S rRNA genes were consistently amplified from the ovarial tissue of three species of vesicomyid clams: Calyptogena magnifica, C. phaseoliformis, and C. pacifica. The nucleotide sequences of the genes amplified from ovaries were identical to those from the respective host symbionts. In situ hybridizations to CG1255R labeled with digoxigenin-11-dUTP were performed on ovarial tissue from each of the vesicomyid clams. Detection of hybrids localized the symbionts to follicle cells surrounding the primary oocytes. These results suggest that vesicomyid clams assure successful, host-specific inoculation of all progeny by using a transovarial mechanism of symbiont transmission.

  16. Identification of Methanotrophic Lipid Biomarkers in Cold-Seep Mussel Gills: Chemical and Isotopic Analysis

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.; Summons, Roger E.; Dowling, Lesley M.; Zahiralis, Karen D.

    1995-01-01

    A lipid analysis of the tissues of a cold-seep mytilid mussel collected from the Louisiana slope of the Gulf of Mexico was used in conjunction with a compound-specific isotope analysis to demonstrate the presence of methanotrophic symbionts in the mussel gill tissue and to demonstrate the host's dependence on bacterially synthesized metabolic intermediates. The gill tissue contained large amounts of group-specific methanotrophic biomarkers, bacteriohopanoids, 4-methylsterols, lipopolysaccharide-associated hydroxy fatty acids, and type I-specific 16:1 fatty acid isomers with bond positions at delta-8, delta-10, and delta-ll. Only small amounts of these compounds were detected in the mantle or other tissues of the host animal. A variety of cholesterol and 4-methylsterol isomers were identified as both free and steryl esters, and the sterol double bond positions suggested that the major bacterially derived gill sterol(11.0% 4(alpha)-methyl-cholesta-8(14), 24-dien-3(beta)-ol) was converted to host cholesterol (64.2% of the gill sterol was cholest-5-en-3(beta)-ol). The stable carbon isotope values for gill and mantle preparations were, respectively, -59.0 and -60.4 per thousand for total tissue, -60.6 and -62.4 per thousand for total lipids, -60.2 and -63.9 per thousand for phospholipid fatty acids, and -71.8 and -73.8 per thousand for sterols. These stable carbon isotope values revealed that the relative fractionation pattern was similar to the patterns obtained in pure culture experiments with methanotrophic bacteria further supporting the conversion of the bacterial methyl-sterol pool.

  17. Identification of Methanotrophic Lipid Biomarkers in Cold-Seep Mussel Gills: Chemical and Isotopic Analysis

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.; Summons, Roger E.; Dowling, Lesley M.; Zahiralis, Karen D.

    1995-01-01

    A lipid analysis of the tissues of a cold-seep mytilid mussel collected from the Louisiana slope of the Gulf of Mexico was used in conjunction with a compound-specific isotope analysis to demonstrate the presence of methanotrophic symbionts in the mussel gill tissue and to demonstrate the host's dependence on bacterially synthesized metabolic intermediates. The gill tissue contained large amounts of group-specific methanotrophic biomarkers, bacteriohopanoids, 4-methylsterols, lipopolysaccharide-associated hydroxy fatty acids, and type I-specific 16:1 fatty acid isomers with bond positions at delta-8, delta-10, and delta-ll. Only small amounts of these compounds were detected in the mantle or other tissues of the host animal. A variety of cholesterol and 4-methylsterol isomers were identified as both free and steryl esters, and the sterol double bond positions suggested that the major bacterially derived gill sterol(11.0% 4(alpha)-methyl-cholesta-8(14), 24-dien-3(beta)-ol) was converted to host cholesterol (64.2% of the gill sterol was cholest-5-en-3(beta)-ol). The stable carbon isotope values for gill and mantle preparations were, respectively, -59.0 and -60.4 per thousand for total tissue, -60.6 and -62.4 per thousand for total lipids, -60.2 and -63.9 per thousand for phospholipid fatty acids, and -71.8 and -73.8 per thousand for sterols. These stable carbon isotope values revealed that the relative fractionation pattern was similar to the patterns obtained in pure culture experiments with methanotrophic bacteria further supporting the conversion of the bacterial methyl-sterol pool.

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

    PubMed Central

    Ruff, S. Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    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

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

    PubMed

    Ruff, S Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    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

  20. Biogeography of deep-sea wood fall, cold seep and hydrothermal vent Ostracoda (Crustacea), with the description of a new family and a taxonomic key to living Cytheroidea

    NASA Astrophysics Data System (ADS)

    Karanovic, Ivana; Brandão, Simone Nunes

    2015-01-01

    Stimulated by finding a novel cytheroid ostracod in a piece of sunken wood retrieved from the sea-bed in the Kuril-Kamchatka Trench, we have reviewed all previously published data on ostracods from similarly ephemeral deep-sea habitats (wood falls, hydrothermal vents and cold seeps). These data are placed in the context of all data on living, deep-sea ostracods from other environments. We confirm previous authors' conclusions that faunas from these ephemeral habitats are similar at the generic level, and include elements common to shallow and deep habitats. However, at the species level, endemism varies from zero at cold seeps, to 35% in wood falls and 60% at hydrothermal vents, which is an indication of the relative longevity of these habitats. Non-endemic species occur also in oligotrophic, deep-sea sediments but not in shallow environments. This is in contradiction to previous assumptions that these ephemeral faunas share more species and with shallow habitats than genera with the oligotrophic, deep-sea sediments. We agree with previous authors that the dispersal strategy of wood fall, vent and seep ostracods includes hitchhiking and we propose that it also includes the ability to survive ingestion by larger, more motile animals. The homogeneity of the faunas from ephemeral habitats collected off the American continent is in stark contrast to the highly endemic fauna found in Northwestern Pacific. This suggests that the ostracods may have biogeographical patterns similar to those previously proposed for other groups of benthos. However, any proposal for a global biogeographical scheme for ostracod distributions will have to await far more comprehensive coverage from presently unstudied regions. Finally, we describe and name a novel species of ostracod from the wood fall collected at a depth of 5229 m in the abyss east to the Kuril-Kamchatka Trench, Northwestern Pacific; erecting a new family Keysercytheridae fam. nov. and a new genus, Keysercythere gen. nov., to

  1. Methane-derived carbonates form at the sediment-bedrock interface in a shallow marine gas seep.

    NASA Astrophysics Data System (ADS)

    Kimball, J.; Ding, H.; Valentine, D. L.

    2006-12-01

    Hydrocarbon seeps occur world-wide, and release large quantities of oil and natural gas to the ocean and atmosphere. One of the world's most prolific hydrocarbon seep fields is located just offshore from Goleta, CA, and serves as the study site for this investigation. In the course of investigating gas fluxes from a 10 m deep coastal seep, samples of seafloor bedrock were collected by scuba diving during a time of low sediment burden. These samples were found to be concretions composed primarily of carbonate-cemented sand. The delta13C values of the carbonate range from -25 to -32 per mille, and indicate a role for methane oxidation in the formation of the carbonates. Long chain fatty acids were extracted from the concretions and were quantified, identified, and analyzed for their 13C composition. Fatty acids typical of sulfate reducing bacteria were observed, and interpreted as a signature of anoxia. Further mineralogical and isotopic studies are planned. From these observations we interpret a shallow water origin for these concretions, whereby the seasonal migration of sand to the seep environment drives anoxia and anaerobic methane oxidation at the sediment-bedrock interface. The alkalinity generated from sulfate reduction causes the precipitation of methane-derived carbonate- which forms a concretion with sand.

  2. Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV).

    PubMed

    Doya, Carolina; Chatzievangelou, Damianos; Bahamon, Nixon; Purser, Autun; De Leo, Fabio C; Juniper, S Kim; Thomsen, Laurenz; Aguzzi, Jacopo

    2017-01-01

    Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs), such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ). Short video-transects were run at 4-h intervals during the first week of successive calendar months, over a 14 month period (February 14th 2013 to April 14th 2014). Within each recorded transect video megafauna abundances were computed and changes in environmental conditions concurrently measured. The responses of fauna to environmental conditions as a proxy of seasonality were assessed through analysis of abundances in a total of 438 video-transects (over 92 h of total footage). 7698 fauna individuals from 6 phyla (Cnidaria, Ctenophora, Arthropoda, Echinodermata, Mollusca, and Chordata) were logged and patterns in abundances of the 7 most abundant taxa (i.e. rockfish Sebastidae, sablefish Anoplopoma fimbria, hagfish Eptatretus stoutii, buccinids (Buccinoidea), undefined small crabs, ctenophores Bolinopsis infundibulum, and Scyphomedusa Poralia rufescens) were identified. Patterns in the reproductive behaviour of the grooved tanner crab (Chionnecetes tanneri) were also indicated. Temporal variations in biodiversity and abundance in megabenthic fauna was significantly influenced by variabilities in flow velocity flow direction (up or down canyon), dissolved oxygen concentration and month of study. Also reported here for the first time are transient mass aggregations of grooved tanner

  3. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny

    PubMed Central

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  4. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny.

    PubMed

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  5. Spatial and temporal characterization of a cold seep-hydrate system (Woolsey Mound, deep-water Gulf of Mexico)

    NASA Astrophysics Data System (ADS)

    Simonetti, Antonello

    Cold seeps are areas where methane is transferred from the lithosphere into the hydrosphere, accounting for the major source of hydrocarbons in seawaters. Formation of gas hydrate in cold seeps modulates the global discharge of methane to the environment. However, cold seeps are dynamic settings where hydrates dissociate on short and long time-scales triggering substantial methane fluxes to the oceans. These methane vents sustain unique ecosystems at the ocean floors and contribute to ocean acidification. Also, the methane can potentially reach the sea surface and be exchanged with the atmosphere contributing to global warming. Understanding how cold seep-hydrate systems (CSHSs) operate through time and space is therefore crucial to evaluate their global impact on ocean biogeochemistry and climate. The area investigated is Woolsey Mound, a CSHS located in the Northern Gulf of Mexico. For the first part of the research, the goal was to determine the spatial distribution of subsurface gas hydrate at this site. In terms of hydrate-reservoir category, Woolsey Mound is classified as "seafloor mound" and "fractured mud". To date, these two categories are poorly constrained worldwide. This study documents a successful integration of high-resolution seismic and core data to detect the spatial distribution of hydrates in such settings. The approach adopted and the model may be applied globally for these reservoir categories. The aim of the second part was to untangle the contentious long-term (thousands to millions of years) dynamics driving methane hydrate dissociation and seepage in CSHSs. Analyses on high-resolution seismic data suggest that tectonics is the main forcing mechanism and that CSHSs may operate independently from eustatic fluctuations. This contradicts the broad consensus in the literature about methane seepage in CSHSs being systematically triggered during sea-level lowstand. The third part of the research aimed to characterize the short-term (years

  6. Restriction to large-scale gene flow vs. regional panmixia among cold seep Escarpia spp. (Polychaeta, Siboglinidae).

    PubMed

    Cowart, Dominique A; Huang, Chunya; Arnaud-Haond, Sophie; Carney, Susan L; Fisher, Charles R; Schaeffer, Stephen W

    2013-08-01

    The history of colonization and dispersal in fauna distributed among deep-sea chemosynthetic ecosystems remains enigmatic and poorly understood because of an inability to mark and track individuals. A combination of molecular, morphological and environmental data improves understanding of spatial and temporal scales at which panmixia, disruption of gene flow or even speciation may occur. Vestimentiferan tubeworms of the genus Escarpia are important components of deep -sea cold seep ecosystems, as they provide long-term habitat for many other taxa. Three species of Escarpia, Escarpia spicata [Gulf of California (GoC)], Escarpia laminata [Gulf of Mexico (GoM)] and Escarpia southwardae (West African Cold Seeps), have been described based on morphology, but are not discriminated through the use of mitochondrial markers (cytochrome oxidase subunit 1; large ribosomal subunit rDNA, 16S; cytochrome b). Here, we also sequenced the exon-primed intron-crossing Haemoglobin subunit B2 intron and genotyped 28 microsatellites to (i) determine the level of genetic differentiation, if any, among the three geographically separated entities and (ii) identify possible population structure at the regional scale within the GoM and West Africa. Results at the global scale support the occurrence of three genetically distinct groups. At the regional scale among eight sampling sites of E. laminata (n = 129) and among three sampling sites of E. southwardae (n = 80), no population structure was detected. These findings suggest that despite the patchiness and isolation of seep habitats, connectivity is high on regional scales.

  7. A molecular gut content study of Themisto abyssorum (Amphipoda) from Arctic hydrothermal vent and cold seep systems.

    PubMed

    Olsen, Bernt Rydland; Troedsson, Christofer; Hadziavdic, Kenan; Pedersen, Rolf B; Rapp, Hans Tore

    2014-08-01

    The use of DNA as a marker for prey inside the gut of predators has been instrumental in further understanding of known and unknown interactions. Molecular approaches are in particular useful in unavailable environments like the deep sea. Trophic interactions in the deep sea are difficult to observe in situ, correct deep-sea experimental laboratory conditions are difficult to obtain, animals rarely survive the sampling, or the study organisms feed during the sampling due to long hauls. Preliminary studies of vent and seep systems in the Nordic Seas have identified the temperate-cold-water pelagic amphipod Themisto abyssorum as a potentially important predator in these chemosynthetic habitats. However, the prey of this deep-sea predator is poorly known, and we applied denaturing high performance liquid chromatography (DHPLC) to investigate the predator-prey interactions of T. abyssorum in deep-water vent and seep systems. Two deep-water hydrothermally active localities (The Jan Mayen and Loki's Castle vent fields) and one cold seep locality (The Håkon Mosby mud volcano) in the Nordic Seas were sampled, genomic DNA of the stomachs of T. abyssorum was extracted, and 18S rDNA gene was amplified and used to map the stomach content. We found a wide range of organisms including micro-eukaryotes, metazoans and detritus. Themisto abyssorum specimens from Loki's Castle had the highest diversity of prey. The wide range of prey items found suggests that T. abyssorum might be involved in more than one trophic level and should be regarded as an omnivore and not a strict carnivore as have previously been suggested.

  8. Anaerobic degradation of propane and butane by sulfate-reducing bacteria enriched from marine hydrocarbon cold seeps

    PubMed Central

    Jaekel, Ulrike; Musat, Niculina; Adam, Birgit; Kuypers, Marcel; Grundmann, Olav; Musat, Florin

    2013-01-01

    The short-chain, non-methane hydrocarbons propane and butane can contribute significantly to the carbon and sulfur cycles in marine environments affected by oil or natural gas seepage. In the present study, we enriched and identified novel propane and butane-degrading sulfate reducers from marine oil and gas cold seeps in the Gulf of Mexico and Hydrate Ridge. The enrichment cultures obtained were able to degrade simultaneously propane and butane, but not other gaseous alkanes. They were cold-adapted, showing highest sulfate-reduction rates between 16 and 20 °C. Analysis of 16S rRNA gene libraries, followed by whole-cell hybridizations with sequence-specific oligonucleotide probes showed that each enrichment culture was dominated by a unique phylotype affiliated with the Desulfosarcina-Desulfococcus cluster within the Deltaproteobacteria. These phylotypes formed a distinct phylogenetic cluster of propane and butane degraders, including sequences from environments associated with hydrocarbon seeps. Incubations with 13C-labeled substrates, hybridizations with sequence-specific probes and nanoSIMS analyses showed that cells of the dominant phylotypes were the first to become enriched in 13C, demonstrating that they were directly involved in hydrocarbon degradation. Furthermore, using the nanoSIMS data, carbon assimilation rates were calculated for the dominant cells in each enrichment culture. PMID:23254512

  9. Dynamics of cell proliferation and apoptosis reflect different life strategies in hydrothermal vent and cold seep vestimentiferan tubeworms.

    PubMed

    Pflugfelder, Bettina; Cary, S Craig; Bright, Monika

    2009-07-01

    Deep-sea vestimentiferan tubeworms, which live in symbiosis with bacteria, exhibit different life strategies according to their habitat. At unstable and relatively short-lived hydrothermal vents, they grow extremely fast, whereas their close relatives at stable and long-persisting cold seeps grow slowly and live up to 300 years. Growth and age differences are thought to occur because of ecological and physiological adaptations. However, the underlying mechanisms of cell proliferation and death, which are closely linked to homeostasis, growth, and longevity, are unknown. Here, we show by immunohistochemical and ultrastructural cell cycle analyses that cell proliferation activities of the two species studied are higher than in any other characterized invertebrate, being only comparable with tumor and wound-healing processes. The slow growth in Lamellibrachia luymesi from cold seeps results from balanced activities of proliferation and apoptosis in the epidermis. In contrast, Riftia pachyptila from hydrothermal vents grows fast because apoptosis is down-regulated in this tissue. The symbiont-housing organ, the trophosome, exhibits a complex cell cycle and terminal differentiation pattern in both species, and growth is regulated by proliferation. These mechanisms have similarities to the up- and down-regulation of proliferation or apoptosis in various types of tumor, although they occur in healthy animals in this study, thus providing significant insights into the underlying mechanisms of growth and longevity.

  10. Anaerobic degradation of propane and butane by sulfate-reducing bacteria enriched from marine hydrocarbon cold seeps.

    PubMed

    Jaekel, Ulrike; Musat, Niculina; Adam, Birgit; Kuypers, Marcel; Grundmann, Olav; Musat, Florin

    2013-05-01

    The short-chain, non-methane hydrocarbons propane and butane can contribute significantly to the carbon and sulfur cycles in marine environments affected by oil or natural gas seepage. In the present study, we enriched and identified novel propane and butane-degrading sulfate reducers from marine oil and gas cold seeps in the Gulf of Mexico and Hydrate Ridge. The enrichment cultures obtained were able to degrade simultaneously propane and butane, but not other gaseous alkanes. They were cold-adapted, showing highest sulfate-reduction rates between 16 and 20 °C. Analysis of 16S rRNA gene libraries, followed by whole-cell hybridizations with sequence-specific oligonucleotide probes showed that each enrichment culture was dominated by a unique phylotype affiliated with the Desulfosarcina-Desulfococcus cluster within the Deltaproteobacteria. These phylotypes formed a distinct phylogenetic cluster of propane and butane degraders, including sequences from environments associated with hydrocarbon seeps. Incubations with (13)C-labeled substrates, hybridizations with sequence-specific probes and nanoSIMS analyses showed that cells of the dominant phylotypes were the first to become enriched in (13)C, demonstrating that they were directly involved in hydrocarbon degradation. Furthermore, using the nanoSIMS data, carbon assimilation rates were calculated for the dominant cells in each enrichment culture.

  11. Detection of low-chloride fluids beneath a cold seep field on the Nankai accretionary wedge off Kumano, south of Japan

    NASA Astrophysics Data System (ADS)

    Toki, T.; Tsunogai, U.; Gamo, T.; Kuramoto, S.; Ashi, J.

    2004-11-01

    Chemical and isotopic characteristics were determined for interstitial waters extracted from surface sediments in and around dense biological communities on the seafloor of the Nankai accretionary prism off Kumano, south of Japan. We found the following unique features when compared with usual interstitial water samples of normal seafloor in those of samples from bacterial mats on the Oomine Ridge, one of the outer ridge in the Nankai accretionary prism: (1) significant depletion of chloride concentration (maximum 10% depletion from bottom seawater), (2) high concentrations of CH4 and ΣCO2 (more than 660 μmol/kg and 60 mmol/kg, respectively), (3) sulfate depletion (more than 90% depletion compared to bottom seawater), and (4) δDH2O and δ18OH2O depletion [more than 4‰ and 0.7‰ depletion, respectively, compared to standard mean ocean water (SMOW)]. The highest CH4 value among these samples was comparable to the highest value so far reported at one of the most active seep areas in the Nankai Trough, suggesting that these sites should also be regarded as one of the most active seep sites in the Nankai Trough. The chemical compositions of the samples taken from the Oomine Ridge strongly suggest that the fluid originates not from normal sediment-seawater interaction at the sediment surface of hemipelagic environments, but from active seepage of fluids that are rich in CH4 and ΣCO2, depleted in Cl- and SO42-, and low in δDH2O and δ18OH2O compared to normal seawater. Values for the carbon isotopic composition (δ13CCH4) of the dissolved methane in the interstitial fluid [less than -70‰ PeeDee Belemnite (PDB)] and for the C2H6/CH4 ratio (less than 10-3) suggest that the methane originates from microbial production in a relatively shallow layer of sediment, not from the deep sedimentary layer of higher temperature than 60 °C at the depth of more than 300 m below the seafloor. The Cl-=0 mmol/kg extrapolated end-member δDH2O and δ18OH2O values of low

  12. Gammaproteobacterial Methanotrophs Dominate Cold Methane Seeps in Floodplains of West Siberian Rivers

    PubMed Central

    Oshkin, Igor Y.; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V.; Filippov, Illiya V.; Pimenov, Nikolay V.; Liesack, Werner

    2014-01-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h−1, while some seeps emitted up to 5.54 g CH4 h−1. The δ13C value of methane released from these seeps varied between −71.1 and −71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml−1 day−1) were measured in mud samples. Fluorescence in situ hybridization detected 107 methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies. PMID:25063667

  13. Gammaproteobacterial methanotrophs dominate cold methane seeps in floodplains of West Siberian rivers.

    PubMed

    Oshkin, Igor Y; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V; Filippov, Illiya V; Pimenov, Nikolay V; Liesack, Werner; Dedysh, Svetlana N

    2014-10-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  14. Niche differentiation among mat-forming, sulfide-oxidizing bacteria at cold seeps of the Nile Deep Sea Fan (Eastern Mediterranean Sea).

    PubMed

    Grünke, S; Felden, J; Lichtschlag, A; Girnth, A-C; De Beer, D; Wenzhöfer, F; Boetius, A

    2011-07-01

    Sulfidic muds of cold seeps on the Nile Deep Sea Fan (NDSF) are populated by different types of mat-forming sulfide-oxidizing bacteria. The predominant sulfide oxidizers of three different mats were identified by microscopic and phylogenetic analyses as (i) Arcobacter species producing cotton-ball-like sulfur precipitates, (ii) large filamentous sulfur bacteria including Beggiatoa species, and (iii) single, spherical Thiomargarita species. High resolution in situ microprofiles revealed different geochemical settings selecting for the different mat types. Arcobacter mats occurred where oxygen and sulfide overlapped above the seafloor in the bottom water interface. Filamentous sulfide oxidizers were associated with steep gradients of oxygen and sulfide in the sediment. A dense population of Thiomargarita was favored by temporarily changing supplies of oxygen and sulfide in the bottom water. These results indicate that the decisive factors in selecting for different mat-forming bacteria within one deep-sea province are spatial or temporal variations in energy supply. Furthermore, the occurrence of Arcobacter spp.-related 16S rRNA genes in the sediments below all three types of mats, as well as on top of brine lakes of the NDSF, indicates that this group of sulfide oxidizers can switch between different life modes depending on the geobiochemical habitat setting.

  15. Endosymbiotic microflora of the vestimentiferan tubeworm ( Lamellibrachia sp.) from a bathyal cold seep.

    PubMed

    Kimura, Hiroyuki; Higashide, Yukimasa; Naganuma, Takeshi

    2003-01-01

    Gutless vestimentiferan tubeworms are known to harbor endosymbiotic bacteria in a specialized tissue, the trophosome, which consists of lobules. The endosymbionts of vestimentiferans inhabiting sulfide-rich hydrothermal vents are monospecific for their host. In contrast, previous studies suggest that vestimentiferas of methane-rich seeps may host multispecific symbionts. Phylogenetic analysis and dot-blot hybridization of 16S ribosomal RNA genes (16S rDNA) detected 4 operational taxonomic units (OTUs) in the trophosome of the vestimentifera Lamellibrachia species from a bathyal methane-seep. The OTUs were closely related to 16S rDNA of the species belonging to alpha -Proteobacteria ( Sulfitobacter), beta- Proteobacteria ( Janthinobacterium), and gamma -Proteobacteria ( Acinetobacter and Pseudomonas). Localizations of the 4 OTUs within the trophosome were confirmed by in situ hybridization (ISH). ISH signals of the alpha-proteobacterial OTU were observed in the innermost zone of the trophosome lobules. In contrast, ISH signals of the beta- and gamma-proteobacterial OTUs were observed at the periphery of the lobules; however, whether they occur inside or outside the lobules remains unclear. These results support the possibility that the studied methane-seep tubeworm has a microflora composed of multispecific endosymbionts.

  16. U/Th dating of cold-seep carbonates: An initial comparison

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Roberts, Harry H.; Cheng, Hai; Peckmann, Jörn; Bohrmann, Gerhard; Lawrence Edwards, R.; Chen, Duofu

    2010-11-01

    Authigenic carbonates from hydrocarbon seeps are unique archives of past seepage and associated environmental parameters. In order to constrain the ages of a set of seep carbonates and the time involved in carbonate formation, we applied Uranium/Thorium (U/Th) dating to samples from the Gulf of Mexico, the Congo Fan, and the Black Sea. The resulting U/Th ages indicate that environmental conditions must have been favorable for enhanced methane-rich fluid seepage during the time intervals of 53.4 to 1.7 ka BP for the Gulf of Mexico and 45.5 to 3.0 ka BP for the Congo Fan. The seep carbonates from the Black Sea formed at 1.6 to 1.1 ka BP. Our results suggest that enhanced fluid flow during these time intervals was closely related to 1) sea-level variations associated with glacial/interglacial cycles and 2) environmental alterations in the course of Late Quaternary climate change, including variations in bottom-water temperatures that affected the stability of gas hydrate reservoirs.

  17. Cold seep communities in the deep eastern Mediterranean Sea: composition, symbiosis and spatial distribution on mud volcanoes

    NASA Astrophysics Data System (ADS)

    Olu-Le Roy, Karine; Sibuet, Myriam; Fiala-Médioni, Aline; Gofas, Serge; Salas, Carmen; Mariotti, André; Foucher, Jean-Paul; Woodside, John

    2004-12-01

    Two mud volcano fields were explored during the French-Dutch MEDINAUT cruise (1998) with the submersible NAUTILE, one south of Crete along the Mediteranean Ridge at about 2000 m depth (Olimpi mud field) and the other south of Turkey between 1700 and 2000 m depth (Anaximander mud field) where high methane concentrations were measured. Chemosynthetic communities were observed and sampled on six mud volcanoes and along a fault scarp. The communities were dominated by bivalves of particularly small size, belonging to families commonly found at seeps (Mytilidae, Vesicomyidae, Thyasiridae) and to Lucinidae mostly encountered in littoral sulfide-rich sediments and at the shallowest seeps. Siboglinid polychaetes including a large vestimentiferan Lamellibrachia sp. were also associated. At least four bivalve species and one siboglinid are associated with symbiotic chemoautotrophic bacteria, as evidenced by Transmission Electronic Microscopy and isotopic ratio measurements. Among the bivalves, a mytilid harbors both methanotrophic and sulfide-oxidizing bacteria. Video spatial analysis of the community distribution on three volcanoes shows that dense bivalve shell accumulations (mainly lucinids) spread over large areas, from 10% to 38% of the explored areas (2500-15000 m 2) on the different volcanoes. Lamellibrachia sp. had different spatial distribution and variable density in the two mud volcano fields, apparently related with higher methane fluxes in the Anaximander volcanoes and maybe with the instability due to brines in the Olimpi area. The abundance and richness of the observed chemosynthetic fauna and the size of some of the species contrast with the poverty of the deep eastern Mediterranean. The presence of a specialized fauna, with some mollusk genera and species shared with other reduced environments of the Mediterranean, but not dominated by the large bivalves usually found at seeps, is discussed.

  18. Fluid channeling and their effect on the efficiency of benthic methane filter in various seep habitats and sediments

    NASA Astrophysics Data System (ADS)

    Steeb, Philip; Linke, Peter; Treude, Tina

    2014-05-01

    Marine sediments and sub-seafloor gas hydrates build one of the largest methane reservoirs on Earth. Most of the methane ascending in sediments is oxidized by anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor, the so-called "benthic microbial methane filter". The efficiency of the benthic microbial methane filter is controlled by diffusive sulfate supply from seawater and advective methane flux from deep reservoirs. High fluid fluxes reduce the penetration depth of sulfate and limit the filter to a very narrow zone close to the sediment-water interface. However natural and catastrophic fluctuations of methane fluxes (caused e.g. by gas hydrate melting, earthquakes, slope failure) can change the fluid regime and reduce the capability of this greenhouse gas sink. A new Sediment-Flow-Through (SLOT) system was developed to incubate intact sediment cores under controlled fluid regimes. To mimic natural fluid conditions sulfate-free, methane-loaded artificial seawater medium was pumped from the bottom and sulfate-enriched seawater medium was supplied from above. Media and system were kept anoxic and seepage medium was tracked with bromide tracer. Over the entire experiment, the change of geochemical gradients inside the sediment column was monitored in monthly time intervals using porewater extraction/analyses and microsensor measurements. In addition, in- and outflow samples were analyzed for the calculation of methane turnover rates. In the above manner, sediments from different seeps (Eckernförde Bay, Costa Rica, Chile, and the Eastern Mediterranean Sea) and types (gassy sediments, gas hydrates containing sediments, mud volcanoes, sulfur bacteria mats, pogonophoran fields, clam fields) were incubated and monitored up to one year. Moderate to high advective fluid flow rates, which have been reported from natural seeps, were chosen to challenge the benthic microbial methane filter and investigate the response to pulses of methane loaded

  19. Diversity of symbioses between chemosynthetic bacteria and metazoans at the Guiness cold seep site (Gulf of Guinea, West Africa).

    PubMed

    Duperron, Sébastien; Rodrigues, Clara F; Léger, Nelly; Szafranski, Kamil; Decker, Carole; Olu, Karine; Gaudron, Sylvie M

    2012-12-01

    Fauna from deep-sea cold seeps worldwide is dominated by chemosymbiotic metazoans. Recently, investigation of new sites in the Gulf of Guinea yielded numerous new species for which symbiosis was strongly suspected. In this study, symbioses are characterized in five seep-specialist metazoans recently collected from the Guiness site located at ≈ 600 m depth. Four bivalve and one annelid species belonging to families previously documented to harbor chemosynthetic bacteria were investigated using bacterial marker gene sequencing, fluorescence in situ hybridization, and stable isotope analyses. Results support that all five species display chemosynthetic, sulfur-oxidizing γ-proteobacteria. Bacteria are abundant in the gills of bivalves, and in the trophosome of the siboglinid annelid. As observed for their relatives occurring at deeper sites, chemoautotrophy is a major source of carbon for animal nutrition. Although symbionts found in each host species are related to symbionts found in other metazoans from the same families, several incongruencies are observed among phylogenetic trees obtained from the different bacterial genes, suggesting a certain level of heterogeneity in symbiont strains present. Results provide new insights into the diversity, biogeography, and role of symbiotic bacteria in metazoans from the Gulf of Guinea, at a site located at an intermediate depth between the continental shelf and the deep sea.

  20. Diversity of symbioses between chemosynthetic bacteria and metazoans at the Guiness cold seep site (Gulf of Guinea, West Africa)

    PubMed Central

    Duperron, Sébastien; Rodrigues, Clara F; Léger, Nelly; Szafranski, Kamil; Decker, Carole; Olu, Karine; Gaudron, Sylvie M

    2012-01-01

    Fauna from deep-sea cold seeps worldwide is dominated by chemosymbiotic metazoans. Recently, investigation of new sites in the Gulf of Guinea yielded numerous new species for which symbiosis was strongly suspected. In this study, symbioses are characterized in five seep-specialist metazoans recently collected from the Guiness site located at ∼600 m depth. Four bivalve and one annelid species belonging to families previously documented to harbor chemosynthetic bacteria were investigated using bacterial marker gene sequencing, fluorescence in situ hybridization, and stable isotope analyses. Results support that all five species display chemosynthetic, sulfur-oxidizing γ-proteobacteria. Bacteria are abundant in the gills of bivalves, and in the trophosome of the siboglinid annelid. As observed for their relatives occurring at deeper sites, chemoautotrophy is a major source of carbon for animal nutrition. Although symbionts found in each host species are related to symbionts found in other metazoans from the same families, several incongruencies are observed among phylogenetic trees obtained from the different bacterial genes, suggesting a certain level of heterogeneity in symbiont strains present. Results provide new insights into the diversity, biogeography, and role of symbiotic bacteria in metazoans from the Gulf of Guinea, at a site located at an intermediate depth between the continental shelf and the deep sea. PMID:23233246

  1. seeping gas

    NASA Astrophysics Data System (ADS)

    Carlowicz, Michael

    On a recent cruise of the Russian research ship Professor Logachev, scientists from the U.S. Naval Research Laboratory (NRL), the Russian research institute VNI-IOkeangeologia (St. Petersburg), and other institutions found what they believe to be thin white sheets of methane hydrates. The white layer (possibly also mats of chemosynthetic bacteria) covers the center of a deep-sea mud volcano in the Norwegian-Greenland Sea. The Haakon Mosby mud volcano—a “cow-pie-shaped” cold seep that is 1 km in diameter—lies at 1250-m depth and south of Spitsbergen, Norway.

  2. Cold seeps in the eastern Mediterranean a quantitative geological-biological-chemical investigation of causes, processes and implications- a preliminary seismic study

    NASA Astrophysics Data System (ADS)

    Lazar, M.; Schattner, U.

    2009-04-01

    Cold seepage of gas/water from the seafloor is one of the most important indications of active processes occurring in the subsurface of continental margins. The location and development of these seeps is, among other things, associated with mass sedimentary transport, resulting from slope failure (e.g. submarine landslides). Studies have shown that endemic ecological systems tend to develop in the shallow subsurface and seafloor near these sites, whose existence is directly related to utilization of the escaping gas. A large and unknown part of the carbon cycle is connected to the reduction and release of methane to the water column. However a precise evaluation of the fraction that eventually reaches the atmosphere as an important greenhouse gas is unknown. During the past few years a number of studies around the world have focused on the combination of geological, biological and chemical aspects of cold seeps. Despite this, many questions still remain unanswered, such as the geological mechanisms generating the seeps, the chemical composition of the seeps, which biological ecosystems base their existence on the seeps and how microbiological process in the subsurface effect the composition and rate of gas release. The eastern Mediterranean basin is one of the most interesting and least studied regions as far as cold seep systems are concerned. The basin is considered to be an "ecological desert" with respect to available nutrients and biological diversity. Here we present new results from a high-resolution Sparker seismic survey carried out offshore northern Israel to map the location of gas seepages on the seafloor. A number of shallow cores were extracted from the target areas and water was sampled for chemical analysis. These data will be integrated as a pilot for a larger, interdisciplinary study to identify, map and characterize the geology, biology and chemistry of gas seepages in the eastern Mediterranean.

  3. Integrative study of a new cold-seep mussel (Mollusca: Bivalvia) associated with chemosynthetic symbionts in the Marmara Sea

    NASA Astrophysics Data System (ADS)

    Ritt, Bénédicte; Duperron, Sébastien; Lorion, Julien; Sara Lazar, Cassandre; Sarrazin, Jozée

    2012-09-01

    Recently, small Idas-like mussels have been discovered living on carbonate crusts associated with cold-seeps in the Marmara Sea. These mussels, here referred to as Idas-like nov. sp., differ morphologically and genetically from another species identified as Idas aff. modiolaeformis, living in the same type of ecosystem in the Nile Deep-Sea Fan (eastern Mediterranean Sea). A phylogenetic analysis confirms the distinction between the two species, which belong to highly divergent lineages. Carbon stable isotope values, as well as the detection of thiotroph-related bacteria in the gill tissue, support the presence of a symbiotic, thiotroph-derived nutrition. In contrast, Idas aff. modiolaeformis displays six different types of symbionts. Finally our size-frequency data suggest that the recruitment is continuous in the examined area. The present study extends the documented distribution of symbiont-bearing mussels to the Marmara Sea, and contributes to the characterisation of biological communities in this recently explored area.

  4. A phylogenetic perspective on diversity of Galatheoidea (Munida, Munidopsis) from cold-water coral and cold seep communities in the western North Atlantic Ocean

    USGS Publications Warehouse

    Coykendall, Dolly K.; Nizinski, Martha S.; Morrison, Cheryl

    2016-01-01

    Squat lobsters (Galatheoidea and Chirostyloidea), a diverse group of decapod crustaceans, are ubiquitous members of the deep-sea fauna. Within Galatheoidea, the genera Munida and Munidopsis are the most diverse, but accurate estimates of biodiversity are difficult due to morphological complexity and cryptic diversity. Four species of Munida and nine species of Munidopsis from cold-water coral (CWC) and cold seep communities in the northwestern Atlantic Ocean (NWA) and the Gulf of Mexico (GOM) were collected over eleven years and fifteen research cruises in order to assess faunal associations and estimate squat lobster biodiversity. Identification of the majority of specimens was determined morphologically. Mitochondrial COI sequence data, obtained from material collected during these research cruises, was supplemented with published sequences of congeners from other regions. The phylogenetic analysis of Munida supports three of the four NWA and GOM species (M. microphthalma, M. sanctipauli, and M. valida) as closely related taxa. The fourth species, Munida iris, is basal to most other species of Munida, and is closely related to M. rutllanti, a species found in the northeastern Atlantic Ocean (NEA). The majority of the nine species of Munidopsis included in our analyses were collected from chemosynthetic cold seep sites from the GOM. While seep taxa were scattered throughout the phylogenetic tree, four of these species (Munidopsis livida, M. similis, M. bermudezi, and M. species A) from the NWA and the GOM were part of a large eighteen-species clade that included species collected from Pacific Ocean chemosynthetic habitats, such as hydrothermal vents and whale falls. Shinkaia crosnieri was the sister taxon to the chemosynthetic clade, and M. livida was the most basal member of this clade. Munidopsis sp. B, an undescribed species with representative individuals collected from two GOM chemosynthetic sites, exhibited the largest genetic distance from other northern

  5. A phylogenetic perspective on diversity of Galatheoidea (Munida, Munidopsis) from cold-water coral and cold seep communities in the western North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Katharine Coykendall, D.; Nizinski, Martha S.; Morrison, Cheryl L.

    2017-03-01

    Squat lobsters (Galatheoidea and Chirostyloidea), a diverse group of decapod crustaceans, are ubiquitous members of the deep-sea fauna. Within Galatheoidea, the genera Munida and Munidopsis are the most diverse, but accurate estimates of biodiversity are difficult due to morphological complexity and cryptic diversity. Four species of Munida and nine species of Munidopsis from cold-water coral (CWC) and cold seep communities in the northwestern Atlantic Ocean (NWA) and the Gulf of Mexico (GOM) were collected over eleven years and fifteen research cruises in order to assess faunal associations and estimate squat lobster biodiversity. Identification of the majority of specimens was determined morphologically. Mitochondrial COI sequence data, obtained from material collected during these research cruises, was supplemented with published sequences of congeners from other regions. The phylogenetic analysis of Munida supports three of the four NWA and GOM species (M. microphthalma, M. sanctipauli, and M. valida) as closely related taxa. The fourth species, Munida iris, is basal to most other species of Munida, and is closely related to M. rutllanti, a species found in the northeastern Atlantic Ocean (NEA). The majority of the nine species of Munidopsis included in our analyses were collected from chemosynthetic cold seep sites from the GOM. While seep taxa were scattered throughout the phylogenetic tree, four of these species (Munidopsis livida, M. similis, M. bermudezi, and M. species A) from the NWA and the GOM were part of a large eighteen-species clade that included species collected from Pacific Ocean chemosynthetic habitats, such as hydrothermal vents and whale falls. Shinkaia crosnieri was the sister taxon to the chemosynthetic clade, and M. livida was the most basal member of this clade. Munidopsis sp. B, an undescribed species with representative individuals collected from two GOM chemosynthetic sites, exhibited the largest genetic distance from other northern

  6. Macondo oil in deep-sea sediments: Part 2 - Distribution and distinction from background and natural oil seeps.

    PubMed

    Stout, Scott A; Payne, James R; Ricker, Robert W; Baker, Gregory; Lewis, Christopher

    2016-10-15

    Following the Deepwater Horizon oil spill, the spilled Macondo oil was severely weathered during its transport within the deep-sea plume as discrete particles, which were subsequently deposited on the seafloor. The Macondo oil deposited in deep-sea sediments was distinguished from ambient (background) hydrocarbons and naturally-seeped and genetically-similar oils in the Mississippi Canyon region using a forensic method based upon a systematic, multi-year study of 724 deep-sea sediment cores collected in late 2010 and 2011. The method relied upon: (1) chemical fingerprinting of the distinct features of the wax-rich, severely-weathered Macondo oil; (2) hydrocarbon concentrations, considering a core's proximity to the Macondo well or to known or apparent natural oil seeps, and also vertically within a core; and (3) results from proximal cores and flocculent material from core supernatants and slurp gun filters. The results presented herein establish the geographic extent of "fingerprintable" Macondo oil recognized on the seafloor in 2010/2011.

  7. Greigite as a marker of paleo sulphate methane transition zone (SMTZ) in cold seep environment of Krishna-Godavari (KG) Basin, Bay of Bengal, India.

    NASA Astrophysics Data System (ADS)

    B, F. K.; Dewangan, P.; Usapkar, A.; Mazumdar, A.; Kocherla, M.; Tammisetti, R.; Khalap, S. T.; Satelkar, N. P.; Mehrtens, T.; Rosenauer, A.

    2014-12-01

    Rockmagnetic results and electron microscopic observations on a sediment core retrieved from a proven cold seep environment of Krishna-Godavari (KG) Basin revealed an anomalously magnetically enhanced zone (17 - 23 mbsf) below the present-day SMTZ in the KG offshore basin. This zone is characterized by higher SIRM / k, kARM / SIRM and kfd % values indicating the presence of fine grained superparamagnetic (SP) sized ferrimagnetic iron sulphides minerals such as greigite formed due to anaerobic oxidation of methane (AOM). Identification of such mineral phases and understanding the mechanism of their formation and preservation is of vital importance which could provide better understanding of the geochemical processes on the paleo - SMTZ. Magnetic concentrates extracted from this zone were characterised by transmission electron microscopy and energy dispersive X- ray spectrometry. We observed two possible occurrences of magnetic phases within this sediment depths 17 - 23 mbsf. (a) authigenically formed SP sized ferrimagnetic inclusions of magnetite, pyrite and greigite within matrix of host siliceous grain, (b) poorly crystallized fine-grained magnetite with ill defined grain boundary possibily formed extracellulary by magnetotactic bacterias through biologically-induced mineralization. High methane fluxes as observed in this basin provides suitable environment for the formation of greigite in the vicinity of SMTZ. We hypothesize that due to availability of residual iron and low supply of hydrogen sulphide caused by downwards diffusion lead to preservation of greigite. The occurence of greigite as inclusion within the host silicate matrix might explain its preservation in this zone in spite of intense pyritization. The greigite would otherwise be converted to stable-form pyrite. It is challenging to explain the origin of biologically produced magnetite within 17 - 23 mbsf as it is expected to dissolve in this zone due to intense pyritization.

  8. Modification of sediment geochemistry by the hydrocarbon seep tubeworm Lamellibrachia luymesi: A combined empirical and modeling approach

    NASA Astrophysics Data System (ADS)

    Dattagupta, Sharmishtha; Arthur, Michael A.; Fisher, Charles R.

    2008-05-01

    The sulfide-oxidizing symbiotic tubeworm Lamellibrachia luymesi is a dominant member of deep-sea hydrocarbon seep ecosystems on the Gulf of Mexico seafloor. This tubeworm forms large aggregations that can live for centuries and provide habitat for an assortment of associated fauna. Previous studies have suggested that persistence of these tubeworms for such long time periods is contingent upon their ability to supply sediments with sulfate. To examine this hypothesis, we characterized the tubeworm's geochemical environment using pore water peepers and compared the measured depth profiles with those predicted by a sulfur diffusion-reaction-supply model. We found a large range of sulfide concentrations in the tubeworm habitat, indicating that this species can live under conditions of both high and low sulfide availability. In sediments rich in hydrocarbons, we found compelling evidence that tubeworms enhance microbial sulfide production, likely through a combination of sulfide uptake and sulfate release through their root-like structures buried in the sediment. Our in situ empirical data combined with the results of the geochemical model corroborate previous physiological studies that indicate that tubeworms release between 70% and 90% of the sulfate produced during sulfide oxidation by their symbionts across their roots into the surrounding sediment. In sediments low in hydrocarbon content, sulfide production is hydrocarbon-limited rather than sulfate-limited, and our model predicts that tubeworm growth could be limited by low sulfide availability.

  9. In situ Determination of Pore-water pH in Reducing Sediments near Methane Seeps and Vents by Laser Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Peltzer, E. T.; Walz, P. M.; Luna, M.; Zhang, X.; Brewer, P. G.

    2015-12-01

    Sediments near methane vents and seeps are often anoxic in nature due to the microbial oxidation of organic matter. When the pore-water oxygen is consumed, the microbial population resorts to using sulfate as the terminal electron receptor. For the anaerobic oxidation of methane, the net reaction is: CH4 + SO42- = HCO3- + HS- + H2O. Hydrogen sulfide produced by this reaction dissociates into bisulfide in proportion to the pore-water pH. Since the first pK of H2S is about 7 and close to the in situ pore-water pH, it satisfies the criteria for a useful pH indicating dye. Although the two forms of hydrogen sulfide are not visually discernable by the human eye, these two forms have distinct Raman spectra and thus can be easily quantified using an in situ spectrometer. The relative Raman cross-sections of the hydrogen sulfide species were determined in the laboratory across a range of relevant pH values and at the approximate salinity (ionic strength) and temperature of deep-sea pore waters. With this calibration, it is simple to compute the pore-water pH from the relative abundance of the two sulfide species: pH = pK1 + log10([HS-]/[H2S]). Pore-water profiles were investigated at several sites in the Santa Monica basin around methane mounds, gas vents and cold seeps. A titanium pore-water probe with a stainless steel frit was used to filter and collect pore-water samples at 5-10 cm intervals in the top 50-60 cm of sediment. Filtration and collection of the pore-water samples was usually accomplished in 5-10 minutes, with acquisition of the laser Raman spectra requiring only 2-4 minutes additional time. Vertical profiles of sulfate, total sulfide (H2S + HS-), methane and pH were collected simultaneously using the laser Raman spectrometer and pore-water profile sampler. Sulfate was observed to decrease from seawater concentrations to below detection limits while both methane and total sulfide increased proportionally to the sulfate loss. Once total sulfide concentrations

  10. Megafauna recovered from a cold hydrocarbon seep in the deep Alaskan Beaufort Sea, including a new species of Axinus (Thracidae: Bivalvia: Mollusca)

    NASA Astrophysics Data System (ADS)

    Powell, C. L.; Valentich-Scott, P.; Lorenson, T. D.; Edwards, B. D.

    2011-12-01

    Several specimens of a new species of Axinus and a single well-worn gastropod columella provisionally assigned to the genus Neptunea (Buccinidae: Gastropoda: Mollusca) were recently recovered from at least two cores, the longest of which is 5.72 m long, from a large seafloor mound, informally named the Canning Seafloor Mound (CSM). The CSM is located at 2,530 m water depth on the Alaskan Beaufort Sea slope north of Camden Bay and is a fluid explosion feature containing methane hydrate and methane-saturated sediments overlying a folded and faulted deep basin. Only two modern species of Axinus are currently known. Axinus grandis (Verrill & Smith, 1885) is a northern Atlantic species and the recently described species, A. cascadiensis Oliver and Holmes (2007), is only known from Baby Bare Seamount, Cascadia Basin, northeastern Pacific Ocean. Common fragments, single valves, and a single articulated specimen represent this new Axinus species. These shells were distributed over nearly the entire length of the primary core. All specimens show wear and (or) dissolution. The age of these specimens is unknown and no living representatives were encountered. The genus Axinus has a fossil record back to the early Eocene in England and the Paleocene and Eocene in Egypt. Biogeographically the genus appears to have originated in the Tethys Sea and became established in the Atlantic Ocean during the Eocene, spreading across the Arctic Ocean in the late Tertiary. With the opening of the Bering Strait in the latest Miocene or early Pliocene the genus Axinus migrated southwest into the northeast Pacific. Interestingly, hydrocarbon seep deposits are also present on the adjacent North Slope of Alaska in the Marsh Anticline at Carter Creek, Camden Bay. These rocks, the Nuwok beds, contain abundant Thracidae bivalve of the genus Thracia, but not Axinus, however the rocks also represent cold seep deposits. These rocks have been variously dated from Oligocene to Pliocene and the exact age

  11. Impact of anaerobic oxidation of methane on the geochemical cycle of redox-sensitive elements at cold-seep sites of the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Hu, Yu; Feng, Dong; Liang, Qianyong; Xia, Zhen; Chen, Linying; Chen, Duofu

    2015-12-01

    Cold hydrocarbon seepage is a frequently observed phenomenon along continental margins worldwide. However, little is known about the impact of seeping fluids on the geochemical cycle of redox-sensitive elements. Pore waters from four gravity cores (D-8, D-5, D-7, and D-F) collected from cold-seep sites of the northern South China Sea were analyzed for SO42-, Mg2+, Ca2+, Sr2+, dissolved inorganic carbon (DIC), δ13CDIC, dissolved Fe, Mn, and trace elements (e.g. Mo, U). The sulfate concentration-depth profiles, δ13CDIC values and (ΔDIC+ΔCa2++ΔMg2+)/ΔSO42- ratios suggest that organoclastic sulfate reduction (OSR) is the dominant process in D-8 core. Besides OSR, anaerobic oxidation of methane (AOM) is partially responsible for depletion of sulfate at D-5 and D-7 cores. The sulfate consumption at D-F core is predominantly caused by AOM. The depth of sulfate-methane interface (SMI) and methane diffusive flux of D-F core are calculated to be ~7 m and 0.035 mol m-2 yr-1, respectively. The relatively shallow SMI and high methane flux at D-F core suggest the activity of gas seepage in this region. The concentrations of dissolved uranium (U) were inferred to decrease significantly within the iron reduction zone. It seems that AOM has limited influence on the U geochemical cycling. In contrast, a good correlation between the consumption of sulfate and the removal of molybdenum (Mo) suggests that AOM has a significantly influence on the geochemical cycle of Mo at cold seeps. Accordingly, cold seep environments may serve as an important potential sink in the marine geochemical cycle of Mo.

  12. Ampharetidae (Annelida: Polychaeta) from cold seeps off Pakistan and hydrothermal vents off Taiwan, with the description of three new species.

    PubMed

    Reuscher, Michael G; Fiege, Dieter

    2016-07-20

    The new ampharetid species Eclysippe yonaguniensis sp. nov. and Glyphanostomum bilabiatum sp. nov. from the Yonaguni Knoll IV hydrothermal field off the coast of Taiwan and Pavelius makranensis sp. nov. from the cold seeps in the Makran accretionary prism off the coast of Pakistan are described. Amage cf. ehlersi Reuscher, Fiege & Imajima, 2015 and Anobothrus dayi Imajima, Reuscher & Fiege, 2013 are newly recorded from the Yonaguni Knoll IV hydrothermal field.

  13. Initial results of comparing cold-seep carbonates from mussel- and tubeworm-associated environments at Atwater Valley lease block 340, northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Roberts, Harry H.

    2010-11-01

    Chemosymbiotic macrofauna (such as mussels and tubeworms) and authigenic carbonates are typical of many hydrocarbon seeps. To address whether mussels and tubeworms could impact the sediment geochemistry of their habitat where authigenic carbonates are precipitated, a comparative study of petrographic and geochemical features of the authigenic carbonates from mussel- and tubeworm-associated environments at hydrocarbon seeps in Atwater Valley lease area block 340 (AT340) of the Gulf of Mexico was undertaken. Both mussel- and tubeworm-associated carbonates are dominated by high-magnesium calcite (HMC) and aragonite, and two tubeworm-associated carbonate samples have minor amounts of dolomite. The δ13C values of all carbonates are low, ranging from -60.8‰ to -35.5‰ PDB. Although there is much overlap, surprisingly the δ13C values of mussel-associated carbonates are generally higher than those of tubeworm-associated carbonates (-51.8‰ vs. -54.8‰ for an average of over 60 subsamples). It is suggested that (1) carbon isotopic vital effect of seep mussels and tubeworms, (2) fluid physical pumping of mussels, and (3) release of sulfate by tubeworm roots may be responsible for the relatively lower δ13C values of tubeworm-associated carbonates. It has been suggested that the heterogeneities in mineralogy and stable carbon isotope geochemistry of the seep carbonates may be attributed to the activity of macrofauna (mussels and tubeworms) and associated microbes. Our observations also suggest that at AT340 the geochemical evolution of seep macrofauna is from a mussel-dominated environment to a mixed mussel-tubeworm environment, and finally to a mostly tubeworm-dominated environment. This evolution is controlled mainly by the habitat, e.g., hydrocarbon seep flux.

  14. "The Ruins": Large cold seep sandstone chimneys in the upper Miocene Santa Margarita Sandstone, Scotts Valley, CA

    NASA Astrophysics Data System (ADS)

    Schwartz, H.; Bazan, C.; Perry, F.; Garrison, R. E.

    2012-12-01

    mode of formation of chimneys/slabs or evolution over time of the fluids that produced successive generations of chimney cements. For instance, the heaviest δ13C values (-7.73‰ to -1.95‰) are associated with slabs, but some slabs have δ13C values as light as -17.82‰. We conclude, on the basis of their geometry and geochemistry, that the once-famous columns at the Ruins represent a field of exhumed cold seep chimneys (and related authigenic features) that originally formed around rising columns of methane-rich fluids in the shallow marine subsurface. Their linear distribution suggests that a fault or fracture focused seepage locally. Somewhat younger cold seep chimneys of similar scale occur in the Santa Cruz Mudstone ~15 km west of the Ruins and it is likely that both seep sites are related to Miocene hydrocarbon generation and fluid mobility, as evidenced by widespread coastal exposures of bitumen-saturated sandstones and sandstone injectites. The Ruins site provides the oldest evidence for seepage within this transform continental margin fluid system and shows that the region of fluid expulsion was broader than previously recognized.

  15. Biosurfactant-producing yeast isolated from Calyptogena soyoae (deep-sea cold-seep clam) in the deep sea.

    PubMed

    Konishi, Masaaki; Fukuoka, Tokuma; Nagahama, Takahiko; Morita, Tomotake; Imura, Tomohiro; Kitamoto, Dai; Hatada, Yuji

    2010-08-01

    We describe a detailed structure determination of biosurfactant produced by Pseudozyma hubeiensis SY62, which was newly isolated from Calyptogena soyoae (deep-sea cold-seep clam, Shirouri-gai) at 1156 m in Sagami bay. P. hubeiensis SY62 was taxonomically slightly different from the P. hubeiensis type strain, which produces biosurfactants. Glycolipid production by the strain was also slightly different from those of previously reported strains. BS productivity was estimated to be around 30 g/l from the weight of the crude extract. At least five different spots of glycolipid biosurfactants (BSs) were detected by TLC. Results of nuclear magnetic resonance spectroscopies indicated the major product, namely MEL-C (4-O-[4'-O-acetyl-2',3'-di-O-alka(e)noil-beta-d-mannopyranosyl]-d-erythritol), as a promising BS. By further structural determination, the major fatty acids of MEL-C were estimated to be saturated C(6), C(10), and C(12) acids, which were shorter than those of previously reported MEL-C. Furthermore, (1)H-NMR spectra implied the presence of C(2) acids as acyl groups. According to surface tension determination, the novel MEL-C showed larger critical micelle concentration (1.1x10(-5) M) than conventional MEL-C which bound C(10) and C(12) acids (9.1x10(-6) M). From these results, shorter fatty acids would confer hydrophilicity onto the novel MEL-C.

  16. Spawning, development, and the duration of larval life in a deep-sea cold-seep mussel.

    PubMed

    Arellano, Shawn M; Young, Craig M

    2009-04-01

    We describe culturing techniques and development for the cold-seep mussel "Bathymodiolus" childressi, the only deep-sea bivalve for which development has been detailed. Spawning was induced in mature mussels by injection of 2 mmol l(-1) serotonin into the anterior adductor muscle. The mean egg diameter is 69.15 +/- 2.36 microm (+/-S.D.; n = 50) and eggs are negatively buoyant. Cleavages are spiral and at 7-8 degrees C occur at a rate of one per 3-9 h through hatching, with free-swimming blastulae hatching by 40 h and shells beginning to develop by day 12. When temperature was raised to 12-14 degrees C after hatching, larvae developed to D-shell veligers by day 8 without being fed. Egg size and larval shell morphology indicate that "B." childressi has a planktotrophic larva, but we did not observe feeding in culture. Wide distribution of this species throughout the Gulf of Mexico and amphi-Atlantic distributions of closely related congeners suggest that larvae may spend extended periods in the plankton. Duration of larval life was estimated for "B." childressi by comparing calculated settlement times to known spawning seasons. These estimates suggest variability in the larval duration, with individuals spending more than a year in the plankton.

  17. Synchronized dynamics of bacterial niche-specific functions during biofilm development in a cold seep brine pool.

    PubMed

    Zhang, Weipeng; Wang, Yong; Bougouffa, Salim; Tian, Renmao; Cao, Huiluo; Li, Yongxin; Cai, Lin; Wong, Yue Him; Zhang, Gen; Zhou, Guowei; Zhang, Xixiang; Bajic, Vladimir B; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2015-10-01

    The biology of biofilm in deep-sea environments is barely being explored. Here, biofilms were developed at the brine pool (characterized by limited carbon sources) and the normal bottom water adjacent to Thuwal cold seeps. Comparative metagenomics based on 50 Gb datasets identified polysaccharide degradation, nitrate reduction and proteolysis as enriched functional categories for brine biofilms. The genomes of two dominant species: a novel Deltaproteobacterium and a novel Epsilonproteobacterium in the brine biofilms were reconstructed. Despite rather small genome sizes, the Deltaproteobacterium possessed enhanced polysaccharide fermentation pathways, whereas the Epsilonproteobacterium was a versatile nitrogen reactor possessing nar, nap and nif gene clusters. These metabolic functions, together with specific regulatory and hypersaline-tolerant genes, made the two bacteria unique compared with their close relatives, including those from hydrothermal vents. Moreover, these functions were regulated by biofilm development, as both the abundance and the expression level of key functional genes were higher in later stage biofilms, and co-occurrences between the two dominant bacteria were demonstrated. Collectively, unique mechanisms were revealed: (i) polysaccharides fermentation, proteolysis interacted with nitrogen cycling to form a complex chain for energy generation, and (ii) remarkably exploiting and organizing niche-specific functions would be an important strategy for biofilm-dependent adaptation to the extreme conditions.

  18. Special Issue ;Sediment cascades in cold climate geosystems;

    NASA Astrophysics Data System (ADS)

    Morche, David; Krautblatter, Michael; Beylich, Achim A.

    2017-06-01

    This Editorial introduces the Special Issue on sediment cascades in cold climate geosystems that evolved from the eighth I.A.G./A.I.G. SEDIBUD (Sediment Budgets in Cold Environments; http://www.geomorph.org/sedibud-working-group/) workshop. The workshop was held from 1st to 4th September 2014 at the Environmental Research Station ;Schneefernerhaus; (http://www.schneefernerhaus.de/en/home.html) located at Mt. Zugspitze, the highest peak of Germany, (2962 m asl). Paper and poster presentations focused on observations, measurements and modeling of geomorphological processes in sediment cascades in cold climate geosystems. This resulting Special Issue brings together ten selected contributions from arctic and alpine environments.

  19. Novel alkane hydroxylase gene (alkB) diversity in sediments associated with hydrocarbon seeps in the Timor Sea, Australia.

    PubMed

    Wasmund, Kenneth; Burns, Kathryn A; Kurtböke, D Ipek; Bourne, David G

    2009-12-01

    Hydrocarbon seeps provide inputs of petroleum hydrocarbons to widespread areas of the Timor Sea. Alkanes constitute the largest proportion of chemical components found in crude oils, and therefore genes involved in the biodegradation of these compounds may act as bioindicators for this ecosystem's response to seepage. To assess alkane biodegradation potential, the diversity and distribution of alkane hydroxylase (alkB) genes in sediments of the Timor Sea were studied. Deduced AlkB protein sequences derived from clone libraries identified sequences only distantly related to previously identified AlkB sequences, suggesting that the Timor Sea maybe a rich reservoir for novel alkane hydroxylase enzymes. Most sequences clustered with AlkB sequences previously identified from marine Gammaproteobacteria though protein sequence identities averaged only 73% (with a range of 60% to 94% sequence identities). AlkB sequence diversity was lower in deep water (>400 m) samples off the continental slope than in shallow water (<100 m) samples on the continental shelf but not significantly different in response to levels of alkanes. Real-time PCR assays targeting Timor Sea alkB genes were designed and used to quantify alkB gene targets. No correlation was found between gene copy numbers and levels of hydrocarbons measured in sediments using sensitive gas chromatography-mass spectrometry techniques, probably due to the very low levels of hydrocarbons found in most sediment samples. Interestingly, however, copy numbers of alkB genes increased substantially in sediments exposed directly to active seepage even though only low or undetectable concentrations of hydrocarbons were measured in these sediments in complementary geochemical analyses due to efficient biodegradation.

  20. Molecular characterization of bacteria associated with the trophosome and the tube of Lamellibrachia sp., a siboglinid annelid from cold seeps in the eastern Mediterranean.

    PubMed

    Duperron, Sébastien; de Beer, Dirk; Zbinden, Magali; Boetius, Antje; Schipani, Vanessa; Kahil, Nacera; Gaill, Françoise

    2009-09-01

    Specimens of Lamellibrachia (Annelida: Siboglinidae) were recently discovered at cold seeps in the eastern Mediterranean. In this study, we have investigated the phylogeny and function of intracellular bacterial symbionts inhabiting the trophosome of specimens of Lamellibrachia sp. from the Amon mud volcano, as well as the bacterial assemblages associated with their tube. The dominant intracellular symbiont of Lamellibrachia sp. is a gammaproteobacterium closely related to other sulfide-oxidizing tubeworm symbionts. In vivo uptake experiments show that the tubeworm relies on sulfide for its metabolism, and does not utilize methane. Bacterial communities associated with the tube form biofilms and occur from the anterior to the posterior end of the tube. The diversity of 16S rRNA gene phylotypes includes representatives from the same divisions previously identified from the tube of the vent species Riftia pachyptila, and others commonly found at seeps and vents.

  1. Investigating Microbial Activity in Diazotrophic Methane Seep Sediment via Transcript Analysis and Single-Cell FISH-NanoSIMS

    NASA Astrophysics Data System (ADS)

    Dekas, A. E.; Connon, S. A.; Chadwick, G.; Orphan, V. J.

    2012-12-01

    Methane seep microbial ecosystems are phylogenetically diverse and physiologically complex, and require culture-independent techniques to accurately investigate metabolic activity. In the present study we combine an RNA analysis of four key microbial genes with FISH-NanoSIMS analysis of single cells to determine the diversity of nitrogen fixing microorganisms (diazotrophs) present at a deep-sea methane-seeping site, as well as investigate the methane-dependency of a variety of community members. Recently, methane-dependent nitrogen fixation was observed in Mound 12 Costa Rica sediments, and was spatially correlated with the abundance of aggregates of anaerobic methanotrophic archaea (ANME) and sulfate reducing bacterial symbionts (SRB). Combined with the detection of 15N uptake from 15N2 in these aggregates, this suggested that the ANME-SRB aggregates are the primary diazotrophs in seep sediment. However, the diversity of dinitrogenase reductase (nifH) sequences recovered from several deep-sea locales, including Mound 12, suggests a greater diversity of diazotrophs in marine sediment. To investigate the activity of these potential diazotrophs in Mound 12 sediment, we investigated a suite of RNA transcripts in 15N2 incubations in both the presence and absence of methane: nifH, bacterial 16S rRNA, methyl coenzyme M reductase A (mcrA), and adenosine-5'-phosposulfate reductase alpha subunit (aprA). No nifH transcripts were recovered in incubations without methane, consistent with previous measurements lacking 15N2 uptake in the same sediments. The activity of the bacterial community in general, assessed by variable transcription, was also greatly affected by the presence or absence of methane. Single-cell fluorescence in situ hybridization coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS) was employed to confirm diazotrophic activity (15N2 uptake) and protein synthesis (15NH4+ uptake) of particular species implicated as ecologically important by the

  2. [Microbiological processes of the carbon and sulfur cycle in cold methane seeps in the North Atlantic].

    PubMed

    Pimenov, N V; Savvichev, A S; Rusanov, I I; Lein, A Iu; Ivanov, M V

    2000-01-01

    Functioning of microbial communities in surface sediments of the Haakon Mosby underwater mud volcano (lat. 72 degrees N) and in gas seepage fields of the Vestnesa Ridge was investigated using Mir-1 and Mir-2 deep-sea submersibles during the 40th expedition of the research vessel Academician Mstislav Keldysh. Large areas of sedimentary deposits of the Haakon Mosby mud volcano (HMMV) and pockmarks of the Vestnesa Ridge (VR) are covered with bacterial mats 0.1 to 0.5 cm thick. The microbial community making up bacterial mats of the HMMV was predominated by large filamentous bacteria with filaments measuring up to 100 microns in length and 2 to 8 microns in width. The occurrence of rosettes allowed the observed filamentous bacteria to be referred to the morphologically similar genera Leucothrix or Thiothrix. Three morphological types of filamentous bacteria were identified in bacterial mats covering VR pockmarks. Filaments of type one are morphologically similar with representatives of the genera Thioploca or Desmanthos. Type two filaments had numerous inclusions of sulfur and resembled representatives of the genus Thiothrix. The third morphological type was constituted by single filaments made up of tightly connected disk-like cells and can, apparently, be assigned to the genus Beggiatoa. The rates of methane oxidation (up to 1570 microliters C/(dm3 day)) and sulfate reduction (up to 17 mg S/(dm3 day)) measured in surface sediments of HMMV and VR were close to the maximum rates of these processes observed in badly polluted regions of the northwestern shelf of the Black Sea. High rates of microbiological processes correlated with the high number of bacteria. The rate of methane production in sediments studied was notably lower and ranged from 0.1 to 3.5 microliters CH4/(dm3 day). Large areas of the HMMV caldera were populated by pogonophoras, represented by the two species, Sclerolinum sp. and Oligobrachia sp. The mass development of Sclerolinum sp. in the HMMV caldera

  3. Marine oil seeps

    SciTech Connect

    Meyer, R.F. )

    1991-03-01

    Petroleum hydrocarbons of both biogenic and thermogenic origin are common constituents of the marine water column and sediment of the continental shelves. Approximately 0.25 million metric tons of oil per year, constituting about 8% of the oil input into the sea, is derived from natural seeps, the rest being anthropogenic. Seepage has occurred world-wide for millions of years and must have been many times greater in the past, when enormous oil deposits, such as the Orinoco Oil Belt, were first exposed to erosion. Although the amount varies from site to site with time, seepage is pervasive in polar and temperate seas. Marine-seep oil is intensely weathered and thus can be distinguished chemically from recent biogenic or undegraded crude oil. The degraded oil from seeps appears to have little deleterious effect on many marine organisms, which ingest and discharge the oil mostly unmetabolized. Chemical analyses suggest that a very large oil-rich layer in the Sargasso Sea originated from a large and as yet undetected seep. Oil seeps have long been used as guides for oil exploration onshore but have been underutilized for this purpose offshore because of oil-plume drift from the site of the seep and because natural oil slicks may be masked by spilled oil. At least one marine seep, in the Santa Barbara Channel, California, is producing oil and natural gas into two hollow steel pyramids from which the oil is collected by work boats and the natural gas is transported to shore by pipeline. This facility effectively reduces atmospheric pollution, controls marine oil pollution from the largest seep in the area, provides emission credits, and yields a modest economic benefit, but the seep is not known to have been used directly in oil exploration.

  4. Microbial Communities of Deep-Sea Methane Seeps at Hikurangi Continental Margin (New Zealand)

    PubMed Central

    Ruff, S. Emil; Arnds, Julia; Knittel, Katrin; Amann, Rudolf; Wegener, Gunter; Ramette, Alban; Boetius, Antje

    2013-01-01

    The methane-emitting cold seeps of Hikurangi margin (New Zealand) are among the few deep-sea chemosynthetic ecosystems of the Southern Hemisphere known to date. Here we compared the biogeochemistry and microbial communities of a variety of Hikurangi cold seep ecosystems. These included highly reduced seep habitats dominated by bacterial mats, partially oxidized habitats populated by heterotrophic ampharetid polychaetes and deeply oxidized habitats dominated by chemosynthetic frenulate tubeworms. The ampharetid habitats were characterized by a thick oxic sediment layer that hosted a diverse and biomass-rich community of aerobic methanotrophic Gammaproteobacteria. These bacteria consumed up to 25% of the emanating methane and clustered within three deep-branching groups named Marine Methylotrophic Group (MMG) 1-3. MMG1 and MMG2 methylotrophs belong to the order Methylococcales, whereas MMG3 methylotrophs are related to the Methylophaga. Organisms of the groups MMG1 and MMG3 are close relatives of chemosynthetic endosymbionts of marine invertebrates. The anoxic sediment layers of all investigated seeps were dominated by anaerobic methanotrophic archaea (ANME) of the ANME-2 clade and sulfate-reducing Deltaproteobacteria. Microbial community analysis using Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the different seep habitats hosted distinct microbial communities, which were strongly influenced by the seep-associated fauna and the geographic location. Despite outstanding features of Hikurangi seep communities, the organisms responsible for key ecosystem functions were similar to those found at seeps worldwide. This suggests that similar types of biogeochemical settings select for similar community composition regardless of geographic distance. Because ampharetid polychaetes are widespread at cold seeps the role of aerobic methanotrophy may have been underestimated in seafloor methane budgets. PMID:24098632

  5. Microbial communities of deep-sea methane seeps at Hikurangi continental margin (New Zealand).

    PubMed

    Ruff, S Emil; Arnds, Julia; Knittel, Katrin; Amann, Rudolf; Wegener, Gunter; Ramette, Alban; Boetius, Antje

    2013-01-01

    The methane-emitting cold seeps of Hikurangi margin (New Zealand) are among the few deep-sea chemosynthetic ecosystems of the Southern Hemisphere known to date. Here we compared the biogeochemistry and microbial communities of a variety of Hikurangi cold seep ecosystems. These included highly reduced seep habitats dominated by bacterial mats, partially oxidized habitats populated by heterotrophic ampharetid polychaetes and deeply oxidized habitats dominated by chemosynthetic frenulate tubeworms. The ampharetid habitats were characterized by a thick oxic sediment layer that hosted a diverse and biomass-rich community of aerobic methanotrophic Gammaproteobacteria. These bacteria consumed up to 25% of the emanating methane and clustered within three deep-branching groups named Marine Methylotrophic Group (MMG) 1-3. MMG1 and MMG2 methylotrophs belong to the order Methylococcales, whereas MMG3 methylotrophs are related to the Methylophaga. Organisms of the groups MMG1 and MMG3 are close relatives of chemosynthetic endosymbionts of marine invertebrates. The anoxic sediment layers of all investigated seeps were dominated by anaerobic methanotrophic archaea (ANME) of the ANME-2 clade and sulfate-reducing Deltaproteobacteria. Microbial community analysis using Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the different seep habitats hosted distinct microbial communities, which were strongly influenced by the seep-associated fauna and the geographic location. Despite outstanding features of Hikurangi seep communities, the organisms responsible for key ecosystem functions were similar to those found at seeps worldwide. This suggests that similar types of biogeochemical settings select for similar community composition regardless of geographic distance. Because ampharetid polychaetes are widespread at cold seeps the role of aerobic methanotrophy may have been underestimated in seafloor methane budgets.

  6. Comparison of Archaeal and Bacterial Diversity in Methane Seep Carbonate Nodules and Host Sediments, Eel River Basin and Hydrate Ridge, USA.

    PubMed

    Mason, Olivia U; Case, David H; Naehr, Thomas H; Lee, Raymond W; Thomas, Randal B; Bailey, Jake V; Orphan, Victoria J

    2015-10-01

    Anaerobic oxidation of methane (AOM) impacts carbon cycling by acting as a methane sink and by sequestering inorganic carbon via AOM-induced carbonate precipitation. These precipitates commonly take the form of carbonate nodules that form within methane seep sediments. The timing and sequence of nodule formation within methane seep sediments are not well understood. Further, the microbial diversity associated with sediment-hosted nodules has not been well characterized and the degree to which nodules reflect the microbial assemblage in surrounding sediments is unknown. Here, we conducted a comparative study of microbial assemblages in methane-derived authigenic carbonate nodules and their host sediments using molecular, mineralogical, and geochemical methods. Analysis of 16S rRNA gene diversity from paired carbonate nodules and sediments revealed that both sample types contained methanotrophic archaea (ANME-1 and ANME-2) and syntrophic sulfate-reducing bacteria (Desulfobacteraceae and Desulfobulbaceae), as well as other microbial community members. The combination of geochemical and molecular data from Eel River Basin and Hydrate Ridge suggested that some nodules formed in situ and captured the local sediment-hosted microbial community, while other nodules may have been translocated or may represent a record of conditions prior to the contemporary environment. Taken together, this comparative analysis offers clues to the formation regimes and mechanisms of sediment-hosted carbonate nodules.

  7. The effect of pulse venting on anaerobic oxidation of methane and pyrite formation in the cold seep environment, offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Cheng, Wan-Yen; Lin, Saulwood; Tseng, Yi-Ting; Chen, NeiChen; Hsieh, I.-Chih

    2016-04-01

    AOM (Anaerobic oxidation of methane) is a key process in seep environment. Sulfate was consumed during oxidation of methane or organic matter with pyrite as a major end product in the anoxic marine environment. Typical changes observed in the pore water include an increase of methane with depth beneath the SMTZ (sulfate methane transition zone), as a result of diffusion and/or advection, and appearances of a dissolved sulfide maximum underneath a dissolved iron peak with depth. A number of other related biogeochemical processes and end products may register their respective changes in sediments as a result of AOM and related reactions. However, flux, time and duration of gas migration may have changed by either long term processes, e.g., tectonic activities and/or climatic induced sea level changes, or short term, e.g., tidal variations. There is relatively little study addressing termination of gas migrations and subsequent changes in the seep environments. In this study, we will present our study on a seep environment where pulses of gas migration may have occurred with a number of chemical anomalies in sediments. We have collected pore water and sediments for their chemical compositions of sulfate, dissolved sulfide, chloride, organic carbon, carbonate carbon and pyrite as well as echo sounding for flares, and towcam for sea surface topography and benthic community. Our results show that methane gas may have migrated in sediments in carrying out AOM reaction and pyrite formation, however, gas migration may have been relatively short and in pulses. Pulses of gas migration resulted in little or even no sulfate reduction in pore water, but with appearance of dissolved sulfide as well as very high concentrations of pyrite in sediments. Flares were observed but not constantly at the site where chemical anomalies were observed. Pulses of gas migration may come from solid gas hydrate formation and dissociation as evidence from pore water chloride enrichment and

  8. From wetlands to sauropods (?) and cold seeps: New perspectives on methane cycling in the Phanerozoic (Invited)

    NASA Astrophysics Data System (ADS)

    Tripati, A.; Beerling, D.; Bristow, T.; Campbell, K.; Catling, D. C.; Reinhard, C.; Rohrssen, M.; Sample, J. C.

    2013-12-01

    The role of methane in Phanerozoic climate change is a topic of debate. Methane has been implicated as a contributory climate forcing agent to sustained warm climates during the Permo-Carboniferous, the Mesozoic, and the Paleogene. It also has been discussed as a driver of transient warming events including rapid deglaciation marking the end of a hypothesized ';snowball' type glacial era in the run up to the Phanerozoic, the end-Ordovician glaciation, the Permo-Triassic boundary, and the Paleocene-Eocene Thermal Maximum. Here we review evidence for methane's role in Phanerozoic global climate change and present new carbon budget calculations for the Ordovician and Permo-Triassic. In addition, we will highlight some new perspectives on methane cycling, ranging from the possible significance of seawater sulfate concentrations in modulating oceanic anaerobic methane oxidation, methane emissions from the guts of sauropods and ruminants, to the decomposition of methane hydrates at active continental margins triggered by deep fluid flow in accretionary prism sediments during great earthquakes.

  9. Sidescan sonar imagery of widespread fossil and active cold seeps along the central Chilean continental margin

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Weinrebe, Wilhelm; Linke, Peter; Kläschen, Dirk; Bialas, Jörg

    2012-12-01

    The central Chilean subduction zone between 35°S and 37°S was investigated in order to identify, document and possibly understand fluid flow and fluid venting within the forearc region. Several areas were mapped using multibeam bathymetry and backscatter, high-resolution sidescan sonar, chirp subbottom profiling and reflection seismic data. On a subsequent cruise ground-truthing observations were made using a video sled. In general, this dataset shows surprisingly little evidence of fluid venting along the mid-slope region, in contrast to other subduction zones such as Central America and New Zealand. There were abundant indications of active and predominantly fossil fluid venting along the upper slope between 36.5°S and 36.8°S at the seaward margin of an intraslope basin. Here, backscatter anomalies suggest widespread authigenic carbonate deposits, likely the result of methane-rich fluid expulsion. There is unpublished evidence that these fluids are of biogenic origin and generated within the slope sediments, similar to other accretionary margins but in contrast to the erosional margin off Central America, where fluids have geochemical signals indicating an origin from the subducting plate.

  10. Methane sources feeding cold seeps on the shelf and upper continental slope off central Oregon, USA

    NASA Astrophysics Data System (ADS)

    Torres, Marta E.; Embley, Robert W.; Merle, Susan G.; TréHu, Anne M.; Collier, Robert W.; Suess, Erwin; Heeschen, Katja U.

    2009-11-01

    We report on a bathymetric mapping and remotely operated vehicle surveys along the 100-600 m region offshore Oregon from 43°50'N to 44°18'N. We interpret our results in light of available geophysical data, published geotectonic models, and analogous observations of fluid venting and carbonate deposition from 44°30'N to 45°00'N. The methane seepage is defined by juxtaposition of a young prism, where methane is generated by bacterial activity and its release is modulated by gas hydrate dynamics, against older sequences that serve as a source of thermogenic hydrocarbons that vent in the shelf. We hypothesize that collision of a buried ridge with the Siletz Terrane results in uplift of gas hydrate bearing sediments in the oncoming plate and that the resulting decrease in pressure leads to gas hydrate dissociation and methane exolution, which, in turn, may facilitate slope failure. Oxidation of the released methane results in precipitation of carbonates that are imaged as high backscatter along a 550 ± 60 m benthic corridor.

  11. Authigenic carbonates from newly discovered active cold seeps on the northwestern slope of the South China Sea: Constraints on fluid sources, formation environments, and seepage dynamics

    NASA Astrophysics Data System (ADS)

    Liang, Qianyong; Hu, Yu; Feng, Dong; Peckmann, Jörn; Chen, Linying; Yang, Shengxiong; Liang, Jinqiang; Tao, Jun; Chen, Duofu

    2017-06-01

    Authigenic carbonates recovered from two newly discovered active cold seeps on the northwestern slope of the South China Sea have been studied using petrography, mineralogy, stable carbon and oxygen isotopic, as well as trace element compositions, together with AMS 14C ages of shells of seep-dwelling bivalves to unravel fluid sources, formation conditions, and seepage dynamics. The two seeps (ROV1 and ROV2), referred to as 'Haima seeps' herein, are approximately 7 kilometers apart, and are typified by abundant carbonate rocks represented bycrusts and nodules. Aragonite and high-Mg calcite are the main carbonate minerals. Based on low δ13Ccarbonate values ranging from -43.0‰ to -27.5‰ (V-PDB) methane is apparently the predominant carbon source of seep carbonates. The corresponding δ18O values, varying from 2.5‰ to 5.8‰ (V-PDB), mostly are higher than calculated values representing precipitation in equilibrium with seawater (2.5‰ to 3.8‰), which probably reflects past destabilization of locally abundant gas hydrates. In addition, we found that carbonates with bivalve shells are generally aragonite-dominated, and bear no barium enrichment but uranium enrichments, reflecting shallow formation depths close to the seafloor. In contrast, carbonate crusts without bivalve shells and nodules contain more calcite, and are characterized by major molybdenum enrichment and different degrees of barium enrichment, agreeing with precipitation at greater depth under strictly anoxic conditions. AMS 14C ages suggest that a major episode of carbonate precipitation occurred between 6.1 ka and 5.1 ka BP at the Haima seeps, followed by a possibly subordinate episode from approximately 3.9 ka to 2.9 ka BP. The common occurrence of dead bivalves at both sites indicates that chemosynthesis-based communities flourished to a greater extent in the past, probably reflecting a decline of seepage activity in recent times. Overall, these results confirm that authigenic carbonates from

  12. The use of multibeam backscatter and bathymetry as a means of identifying faunal assemblages in a deep-sea cold seep

    NASA Astrophysics Data System (ADS)

    Sen, Arunima; Ondréas, Hélène; Gaillot, Arnaud; Marcon, Yann; Augustin, Jean-Marie; Olu, Karine

    2016-04-01

    Deep-sea ecosystems have attracted considerable commercial interest in recent years because of their potential to sustain a diverse range of mankind's industrial needs. If these systems are to be preserved or exploited in a sustainable manner, mapping habitats and species distributions is critical. As biodiversity at cold-seeps or other deep-sea ecosystems is driven by habitat heterogeneity, imagery is the obvious choice for characterizing these systems and has indeed proven extremely valuable towards mapping biogenic habitats formed by dense aggregations of large sized species, such as coral reefs, tubeworm bushes or bivalve beds. However, the acquisition of detailed images with resolution sufficient for reliable identification is extremely time consuming, labor intensive and highly susceptible to logistical issues. We developed a novel method for quickly mapping cold seep fauna and habitats over large areas, at the scale of squares of kilometers. Our method uses multibeam echosounder bathymetry and acoustic backscatter data, both segmented and reclassified based on topographical features and then combined to obtain a raster containing unique values incorporating both backscatter and bathymetry data. Two datasets, obtained from 30 m and 8 m above the seafloor were used and the results from the two datasets were compared. The method was applied to a cold seep community located in a pockmark in the deep Congo channel and we were able to ground truth the accuracy of our method against images of the area. The two datasets, obtained from different altitudes gave varying results: the 8 m altitude dataset reliably predicted tubeworms and carbonate rock, while the 30 m altitude dataset predicted tubeworms and vesicomyid clams. The 30 m dataset was more accurate than the 8 m altitude dataset in predicting distributions of tubeworms. Overall, all the predictions were quite accurate, with at least 90% of predictions being within 5 m of real distributions.

  13. Relative abundances of methane- and sulphur-oxidising symbionts in the gills of a cold seep mussel and link to their potential energy sources.

    PubMed

    Duperron, S; Guezi, H; Gaudron, S M; Pop Ristova, P; Wenzhöfer, F; Boetius, A

    2011-11-01

    Bathymodiolus mussels are key species in many deep-sea chemosynthetic ecosystems. They often harbour two types of endosymbiotic bacteria in their gills, sulphur- and methane oxidisers. These bacteria take up sulphide and methane from the environment and provide energy to their hosts, supporting some of the most prolific ecosystems in the sea. In this study, we tested whether symbiont relative abundances in Bathymodiolus gills reflect variations in the highly spatially dynamic chemical environment of cold seep mussels. Samples of Bathymodiolus aff. boomerang were obtained from two cold seeps of the deep Gulf of Guinea, REGAB (5°47.86S, 9°42.69E, 3170 m depth) and DIAPIR (6°41.58S, 10°20.94E, 2700 m depth). Relative abundances of both symbiont types were measured by means of 3D fluorescence in situ hybridisation and image analysis and compared considering the local sulphide and methane concentrations and fluxes assessed via benthic chamber incubations. Specimens inhabiting areas with highest methane content displayed higher relative abundances of methane oxidisers. The bacterial abundances correlated also with carbon stable isotope signatures in the mussel tissue, suggesting a higher contribution of methane-derived carbon to the biomass of mussels harbouring higher densities of methane-oxidising symbionts. A dynamic adaptation of abundances of methanotrophs and thiotrophs in the gill could be a key factor optimising the energy yield for the symbiotic system and could explain the success of dual symbiotic mussels at many cold seeps and hydrothermal vents of the Atlantic and Gulf of Mexico.

  14. Genome Reduction and Microbe-Host Interactions Drive Adaptation of a Sulfur-Oxidizing Bacterium Associated with a Cold Seep Sponge

    PubMed Central

    Tian, Ren-Mao; Zhang, Weipeng; Cai, Lin; Wong, Yue-Him; Ding, Wei

    2017-01-01

    ABSTRACT As the most ancient metazoan, sponges have established close relationships with particular microbial symbionts. However, the characteristics and physiology of thioautotrophic symbionts in deep-sea sponges are largely unknown. Using a tailored “differential coverage binning” method on 22-Gb metagenomic sequences, we recovered the nearly complete genome of a sulfur-oxidizing bacterium (SOB) that dominates the microbiota of the cold seep sponge Suberites sp. Phylogenetic analyses suggested that this bacterium (an unclassified gammaproteobacterium termed “Gsub”) may represent a new deep-sea SOB group. Microscopic observations suggest that Gsub is probably an extracellular symbiont. Gsub has complete sulfide oxidation and carbon fixation pathways, suggesting a chemoautotrophic lifestyle. Comparative genomics with other sponge-associated SOB and free-living SOB revealed significant genome reduction in Gsub, characterized by the loss of genes for carbohydrate metabolism, motility, DNA repair, and osmotic stress response. Intriguingly, this scenario of genome reduction is highly similar to those of the endosymbionts in deep-sea clams. However, Gsub has retained genes for phage defense and protein secretion, with the latter potentially playing a role in interactions with the sponge host. In addition, we recovered the genome of an ammonia-oxidizing archaeon (AOA), which may carry out ammonia oxidation and carbon fixation within the sponge body. IMPORTANCE Sponges and their symbionts are important players in the biogeochemical cycles of marine environments. As a unique habitat within marine ecosystems, cold seeps have received considerable interest in recent years. This study explores the lifestyle of a new symbiotic SOB in a cold seep sponge. The results demonstrate that both this sponge symbiont and endosymbionts in deep-sea clams employ similar strategies of genome reduction. However, this bacterium has retained unique functions for immunity and defense

  15. Genome Reduction and Microbe-Host Interactions Drive Adaptation of a Sulfur-Oxidizing Bacterium Associated with a Cold Seep Sponge.

    PubMed

    Tian, Ren-Mao; Zhang, Weipeng; Cai, Lin; Wong, Yue-Him; Ding, Wei; Qian, Pei-Yuan

    2017-01-01

    As the most ancient metazoan, sponges have established close relationships with particular microbial symbionts. However, the characteristics and physiology of thioautotrophic symbionts in deep-sea sponges are largely unknown. Using a tailored "differential coverage binning" method on 22-Gb metagenomic sequences, we recovered the nearly complete genome of a sulfur-oxidizing bacterium (SOB) that dominates the microbiota of the cold seep sponge Suberites sp. Phylogenetic analyses suggested that this bacterium (an unclassified gammaproteobacterium termed "Gsub") may represent a new deep-sea SOB group. Microscopic observations suggest that Gsub is probably an extracellular symbiont. Gsub has complete sulfide oxidation and carbon fixation pathways, suggesting a chemoautotrophic lifestyle. Comparative genomics with other sponge-associated SOB and free-living SOB revealed significant genome reduction in Gsub, characterized by the loss of genes for carbohydrate metabolism, motility, DNA repair, and osmotic stress response. Intriguingly, this scenario of genome reduction is highly similar to those of the endosymbionts in deep-sea clams. However, Gsub has retained genes for phage defense and protein secretion, with the latter potentially playing a role in interactions with the sponge host. In addition, we recovered the genome of an ammonia-oxidizing archaeon (AOA), which may carry out ammonia oxidation and carbon fixation within the sponge body. IMPORTANCE Sponges and their symbionts are important players in the biogeochemical cycles of marine environments. As a unique habitat within marine ecosystems, cold seeps have received considerable interest in recent years. This study explores the lifestyle of a new symbiotic SOB in a cold seep sponge. The results demonstrate that both this sponge symbiont and endosymbionts in deep-sea clams employ similar strategies of genome reduction. However, this bacterium has retained unique functions for immunity and defense. Thus, the

  16. Chemosynthetic trophic support for the benthic community at an intertidal cold seep site at Mocha Island off central Chile

    NASA Astrophysics Data System (ADS)

    Sellanes, Javier; Zapata-Hernández, Germán; Pantoja, Silvio; Jessen, Gerdhard L.

    2011-12-01

    We analyzed C and N stable isotope ratios of benthic fauna and their potential food sources at an intertidal methane seep site and a control site without emanation at Mocha Island (central Chile). The objective was to trace the origin of the main food sources used by the local heterotrophic fauna, based on the hypothesis that chemosynthetic production could be partially fueling the local food web at the seep site. Food sources sampled at both sites included macroalgae, particulate organic matter and bacteria-like filaments found growing over the red algae Gelidium lingulatum within the areas of active methane release. At the control site, located 11 km away from the gas emanation, fauna exhibited moderate δ 13C values ranging from -16.2‰ (in a nereid polychaete) to -14.8‰ (in a cirolanid isopod), which were consistent with those of the potential photosynthetic food sources sampled at this site (-20.2 to -16.5‰). δ 13C values of the photosynthetic food sources at the seep site similarly ranged between -25.4 and -17.9‰. However, a portion of the animals at this site were consistently more 13C-depleted, with δ 13C values close to that of the seeping methane (-43.8‰) and the bacteria-like filaments (-39.2 ± 2.5‰) also collected at this site. Specific examples were the Marphysa sp. polychaetes (δ 13C = -44.7 ± 0.6‰), the Schistomeringos sp. dorvilleid polychaetes (δ 13C = -42.9‰), and the tanaid crustacean Zeuxo marmoratus (δ 13C = -37.3 ± 0.2‰). The significantly higher δ 13C values of the herbivorous gastropod Tegula atra at the seep site (-29.3 ± 3.1‰) than at the control site (-12.6 ± 0.3‰) also indicated differences among sites of the preferred carbon sources of this species. Mixing model estimates indicate that at the seep site bacteria-like filaments could be contributing up to ˜60% of the assimilated diet of selected invertebrates. Furthermore, several indicators of trophic structure, based in isotopic niche metrics, indicate a

  17. A long-term cultivation of an anaerobic methane-oxidizing microbial community from deep-sea methane-seep sediment using a continuous-flow bioreactor.

    PubMed

    Aoki, Masataka; Ehara, Masayuki; Saito, Yumi; Yoshioka, Hideyoshi; Miyazaki, Masayuki; Saito, Yayoi; Miyashita, Ai; Kawakami, Shuji; Yamaguchi, Takashi; Ohashi, Akiyoshi; Nunoura, Takuro; Takai, Ken; Imachi, Hiroyuki

    2014-01-01

    Anaerobic oxidation of methane (AOM) in marine sediments is an important global methane sink, but the physiological characteristics of AOM-associated microorganisms remain poorly understood. Here we report the cultivation of an AOM microbial community from deep-sea methane-seep sediment using a continuous-flow bioreactor with polyurethane sponges, called the down-flow hanging sponge (DHS) bioreactor. We anaerobically incubated deep-sea methane-seep sediment collected from the Nankai Trough, Japan, for 2,013 days in the bioreactor at 10°C. Following incubation, an active AOM activity was confirmed by a tracer experiment using 13C-labeled methane. Phylogenetic analyses demonstrated that phylogenetically diverse Archaea and Bacteria grew in the bioreactor. After 2,013 days of incubation, the predominant archaeal components were anaerobic methanotroph (ANME)-2a, Deep-Sea Archaeal Group, and Marine Benthic Group-D, and Gammaproteobacteria was the dominant bacterial lineage. Fluorescence in situ hybridization analysis showed that ANME-1 and -2a, and most ANME-2c cells occurred without close physical interaction with potential bacterial partners. Our data demonstrate that the DHS bioreactor system is a useful system for cultivating fastidious methane-seep-associated sedimentary microorganisms.

  18. A Long-Term Cultivation of an Anaerobic Methane-Oxidizing Microbial Community from Deep-Sea Methane-Seep Sediment Using a Continuous-Flow Bioreactor

    PubMed Central

    Aoki, Masataka; Ehara, Masayuki; Saito, Yumi; Yoshioka, Hideyoshi; Miyazaki, Masayuki; Saito, Yayoi; Miyashita, Ai; Kawakami, Shuji; Yamaguchi, Takashi; Ohashi, Akiyoshi; Nunoura, Takuro; Takai, Ken; Imachi, Hiroyuki

    2014-01-01

    Anaerobic oxidation of methane (AOM) in marine sediments is an important global methane sink, but the physiological characteristics of AOM-associated microorganisms remain poorly understood. Here we report the cultivation of an AOM microbial community from deep-sea methane-seep sediment using a continuous-flow bioreactor with polyurethane sponges, called the down-flow hanging sponge (DHS) bioreactor. We anaerobically incubated deep-sea methane-seep sediment collected from the Nankai Trough, Japan, for 2,013 days in the bioreactor at 10°C. Following incubation, an active AOM activity was confirmed by a tracer experiment using 13C-labeled methane. Phylogenetic analyses demonstrated that phylogenetically diverse Archaea and Bacteria grew in the bioreactor. After 2,013 days of incubation, the predominant archaeal components were anaerobic methanotroph (ANME)-2a, Deep-Sea Archaeal Group, and Marine Benthic Group-D, and Gammaproteobacteria was the dominant bacterial lineage. Fluorescence in situ hybridization analysis showed that ANME-1 and -2a, and most ANME-2c cells occurred without close physical interaction with potential bacterial partners. Our data demonstrate that the DHS bioreactor system is a useful system for cultivating fastidious methane-seep-associated sedimentary microorganisms. PMID:25141130

  19. Large Vesicomyidae (Mollusca: Bivalvia) from cold seeps in the Gulf of Guinea off the coasts of Gabon, Congo and northern Angola

    NASA Astrophysics Data System (ADS)

    von Cosel, Rudo; Olu, Karine

    2009-12-01

    Two new genera and three new species of large Vesicomyidae are described from cold-seep sites on pockmarks and other sulfide-rich environments in the Gulf of Guinea (tropical east Atlantic) off Gabon, Congo (Brazzaville) and northern Angola, from 500 to 4000 m depth: " Calyptogena" (s.l.) regab n. sp., Wareniconcha (n.g.) guineensis (Thiele and Jaeckel 1931), Elenaconcha guiness n.g. n. sp., and Isorropodon atalantae n. sp. For two other species already taken by the R/V Valdivia in 1898, Calyptogena valdiviae (Thiele and Jaeckel 1931) and Isorropodon striatum (Thiele and Jaeckel 1931) new localities were discovered, and the species are rediscussed. E. guiness n.g. n.sp. is also recorded from off Banc d'Arguin, Mauritania, collected by commercial fishing vessels. The vesicomyid species here treated were encountered in different depth ranges along the Gabon-Congo-Angola margin, between 500 and 4000 m depth, and it was found that, in comparison with the dredge samples taken by the Valdivia expedition off southern Cameroon and off Rio de Oro (both at 2500 m), the same species occur in other depth ranges, in some cases with a vertical difference of more than 1000 m. .That means that the species are not confined to a given depth thought being typical for them and that the characteristics of the biotope are likely to play a major role in the distribution of the vesicomyids associated to cold seeps or other reduced environments along the West African margin.

  20. Late Pleistocene to Holocene sedimentation and hydrocarbon seeps on the continental shelf of a steep, tectonically active margin, southern California, USA

    USGS Publications Warehouse

    Draut, Amy E.; Hart, Patrick E.; Lorenson, T.D.; Ryan, Holly F.; Wong, Florence L.; Sliter, Ray W.; Conrad, James E.

    2009-01-01

    Small, steep, uplifting coastal watersheds are prolific sediment producers that contribute significantly to the global marine sediment budget. This study illustrates how sedimentation evolves in one such system where the continental shelf is largely sediment-starved, with most terrestrial sediment bypassing the shelf in favor of deposition in deeper basins. The Santa Barbara-Ventura coast of southern California, USA, is considered a classic area for the study of active tectonics and of Tertiary and Quaternary climatic evolution, interpretations of which depend upon an understanding of sedimentation patterns. High-resolution seismic-reflection data over >570 km2 of this shelf show that sediment production is concentrated in a few drainage basins, with the Ventura and Santa Clara River deltas containing most of the upper Pleistocene to Holocene sediment on the shelf. Away from those deltas, the major factor controlling shelf sedimentation is the interaction of wave energy with coastline geometry. Depocenters containing sediment 5-20 m thick exist opposite broad coastal embayments, whereas relict material (bedrock below a regional unconformity) is exposed at the sea floor in areas of the shelf opposite coastal headlands. Locally, natural hydrocarbon seeps interact with sediment deposition either to produce elevated tar-and-sediment mounds or as gas plumes that hinder sediment settling. As much as 80% of fluvial sediment delivered by the Ventura and Santa Clara Rivers is transported off the shelf (some into the Santa Barbara Basin and some into the Santa Monica Basin via Hueneme Canyon), leaving a shelf with relatively little recent sediment accumulation. Understanding factors that control large-scale sediment dispersal along a rapidly uplifting coast that produces substantial quantities of sediment has implications for interpreting the ancient stratigraphic record of active and transform continental margins, and for inferring the distribution of hydrocarbon resources

  1. Planktonic and sediment-associated aerobic methanotrophs in two seep systems along the North American margin.

    PubMed

    Tavormina, Patricia L; Ussler, William; Orphan, Victoria J

    2008-07-01

    Methane vents are of significant geochemical and ecological importance. Notable progress has been made toward understanding anaerobic methane oxidation in marine sediments; however, the diversity and distribution of aerobic methanotrophs in the water column are poorly characterized. Both environments play an essential role in regulating methane release from the oceans to the atmosphere. In this study, the diversity of particulate methane monooxygenase (pmoA) and 16S rRNA genes from two methane vent environments along the California continental margin was characterized. The pmoA phylotypes recovered from methane-rich sediments and the overlying water column differed. Sediments harbored the greatest number of unique pmoA phylotypes broadly affiliated with the Methylococcaceae family, whereas planktonic pmoA phylotypes formed three clades that were distinct from the sediment-hosted methanotrophs and distantly related to established methanotrophic clades. Water column-associated phylotypes were highly similar between field sites, suggesting that planktonic methanotroph diversity is controlled primarily by environmental factors rather than geographical proximity. Analysis of 16S rRNA genes from methane-rich waters did not readily recover known methanotrophic lineages, with only a few phylotypes demonstrating distant relatedness to Methylococcus. The development of new pmo primers increased the recovery of monooxygenase genes from the water column and led to the discovery of a highly diverged monooxygenase sequence which is phylogenetically intermediate to Amo and pMMO. This sequence potentiates insight into the amo/pmo superfamily. Together, these findings lend perspective into the diversity and segregation of aerobic methanotrophs within different methane-rich habitats in the marine environment.

  2. Authigenic carbonate formation at hydrocarbon seeps in continental margin sediments: A comparative study

    USGS Publications Warehouse

    Naehr, T.H.; Eichhubl, P.; Orphan, V.J.; Hovland, M.; Paull, C.K.; Ussler, W.; Lorenson, T.D.; Greene, H. Gary

    2007-01-01

    Authigenic carbonates from five continental margin locations, the Eel River Basin, Monterey Bay, Santa Barbara Basin, the Sea of Okhotsk, and the North Sea, exhibit a wide range of mineralogical and stable isotopic compositions. These precipitates include aragonite, low- and high-Mg calcite, and dolomite. The carbon isotopic composition of carbonates varies widely, ranging from -60??? to +26???, indicating complex carbon sources that include 13C-depleted microbial and thermogenic methane and residual, 13C-enriched, bicarbonate. A similarly large variability of ??18O values (-5.5??? to +8.9???) demonstrates the geochemical complexity of these sites, with some samples pointing toward an 18O-enriched oxygen source possibly related to advection of 18O-enriched formation water or to the decomposition of gas hydrate. Samples depleted in 18O are consistent with formation deeper in the sediment or mixing of pore fluids with meteoric water during carbonate precipitation. A wide range of isotopic and mineralogical variation in authigenic carbonate composition within individual study areas but common trends across multiple geographic areas suggest that these parameters alone are not indicative for certain tectonic or geochemical settings. Rather, the observed variations probably reflect local controls on the flux of carbon and other reduced ions, such as faults, fluid conduits, the presence or absence of gas hydrate in the sediment, and the temporal evolution of the local carbon reservoir. Areas with seafloor carbonates that indicate formation at greater depth below the sediment-water interface must have undergone uplift and erosion in the past or are still being uplifted. Consequently, the occurrence of carbonate slabs on the seafloor in areas of active hydrocarbon seepage is commonly an indicator of exhumation following carbonate precipitation in the shallow subsurface. Therefore, careful petrographic and geochemical analyses are critical components necessary for the

  3. Colonization of plant substrates at hydrothermal vents and cold seeps in the northeast Atlantic and Mediterranean and occurrence of symbiont-related bacteria

    PubMed Central

    Szafranski, Kamil M.; Deschamps, Philippe; Cunha, Marina R.; Gaudron, Sylvie M.; Duperron, Sébastien

    2015-01-01

    Reducing conditions with elevated sulfide and methane concentrations in ecosystems such as hydrothermal vents, cold seeps or organic falls, are suitable for chemosynthetic primary production. Understanding processes driving bacterial diversity, colonization and dispersal is of prime importance for deep-sea microbial ecology. This study provides a detailed characterization of bacterial assemblages colonizing plant-derived substrates using a standardized approach over a geographic area spanning the North-East Atlantic and Mediterranean. Wood and alfalfa substrates in colonization devices were deployed for different periods at 8 deep-sea chemosynthesis-based sites in four distinct geographic areas. Pyrosequencing of a fragment of the 16S rRNA-encoding gene was used to describe bacterial communities. Colonization occurred within the first 14 days. The diversity was higher in samples deployed for more than 289 days. After 289 days, no relation was observed between community richness and deployment duration, suggesting that diversity may have reached saturation sometime in between. Communities in long-term deployments were different, and their composition was mainly influenced by the geographical location where devices were deployed. Numerous sequences related to horizontally-transmitted chemosynthetic symbionts of metazoans were identified. Their potential status as free-living forms of these symbionts was evaluated based on sequence similarity with demonstrated symbionts. Results suggest that some free-living forms of metazoan symbionts or their close relatives, such as Epsilonproteobacteria associated with the shrimp Rimicaris exoculata, are efficient colonizers of plant substrates at vents and seeps. PMID:25774156

  4. Colonization of plant substrates at hydrothermal vents and cold seeps in the northeast Atlantic and Mediterranean and occurrence of symbiont-related bacteria.

    PubMed

    Szafranski, Kamil M; Deschamps, Philippe; Cunha, Marina R; Gaudron, Sylvie M; Duperron, Sébastien

    2015-01-01

    Reducing conditions with elevated sulfide and methane concentrations in ecosystems such as hydrothermal vents, cold seeps or organic falls, are suitable for chemosynthetic primary production. Understanding processes driving bacterial diversity, colonization and dispersal is of prime importance for deep-sea microbial ecology. This study provides a detailed characterization of bacterial assemblages colonizing plant-derived substrates using a standardized approach over a geographic area spanning the North-East Atlantic and Mediterranean. Wood and alfalfa substrates in colonization devices were deployed for different periods at 8 deep-sea chemosynthesis-based sites in four distinct geographic areas. Pyrosequencing of a fragment of the 16S rRNA-encoding gene was used to describe bacterial communities. Colonization occurred within the first 14 days. The diversity was higher in samples deployed for more than 289 days. After 289 days, no relation was observed between community richness and deployment duration, suggesting that diversity may have reached saturation sometime in between. Communities in long-term deployments were different, and their composition was mainly influenced by the geographical location where devices were deployed. Numerous sequences related to horizontally-transmitted chemosynthetic symbionts of metazoans were identified. Their potential status as free-living forms of these symbionts was evaluated based on sequence similarity with demonstrated symbionts. Results suggest that some free-living forms of metazoan symbionts or their close relatives, such as Epsilonproteobacteria associated with the shrimp Rimicaris exoculata, are efficient colonizers of plant substrates at vents and seeps.

  5. Cold seep biogenic carbonate crust in the Levantine basin is inhabited by burrowing Phascolosoma aff. turnerae, a sipunculan worm hosting a distinctive microbiota

    NASA Astrophysics Data System (ADS)

    Rubin-Blum, Maxim; Shemesh, Eli; Goodman-Tchernov, Beverly; Coleman, Dwight F.; Ben-Avraham, Zvi; Tchernov, Dan

    2014-08-01

    Biogenic calcium carbonate crusts represent a cryptic habitat that is often associated with hydrocarbon seeps. Most biological observations of these crusts concern the external surfaces and the fauna inhabiting their inner cavities are generally neglected. Exposed carbonates in areas of active seepage at the 1100-m-deep base of the Palmachim slumping feature in the Levantine basin are intensively burrowed by metazoans, especially by sipunculans (peanut worms), identified by genetic and morphological markers as a potentially novel Phascolosoma sp., closely related to Phascolosoma turnerae (Rice, 1985) and named here P. aff. turnerae. Bacterial 16S-based tag encoded FLX amplicon pyrosequencing (bTEFAP) was utilized to analyze the bacterial community associated with P. aff. turnerae. We compared the bacterial community structure in P. aff. turnerae to the bacterial community structure associated with the sediment-water interface in adjacent gas seeps and in biofilm covering the carbonate crust hosting the sipunculan. A distinctive microbiota, capable of chemosynthesis and sulfide detoxification, was found in association with P. aff. turnerae.

  6. Microbial diversity in sediments associated with a shallow methane seep in the tropical Timor Sea of Australia reveals a novel aerobic methanotroph diversity.

    PubMed

    Wasmund, Kenneth; Kurtböke, D Ipek; Burns, Kathryn A; Bourne, David G

    2009-05-01

    This study examined the diversity of Bacteria, Archaea and in particular aerobic methanotrophs associated with a shallow (84 m) methane seep in the tropical Timor Sea, Australia. Seepage of thermogenic methane was associated with a large carbonate hardground covered in coarse carbonate-rich sediments and various benthic organisms such as solitary corals. The diversity of Bacteria and Archaea was studied by analysis of cloned 16S rRNA genes, while aerobic methanotrophic bacteria were quantified using real-time PCR targeting the alpha-subunit of particulate methane monooxygenase (pmoA) genes and diversity was studied by analysis of cloned pmoA genes. Phylogenetic analysis of bacterial and archaeal 16S rRNA genes revealed diverse and mostly novel phylotypes related to sequences previously recovered from marine sediments. A small number of bacterial 16S rRNA gene sequences were related to aerobic methanotrophs distantly related to the genera Methylococcus and Methylocaldum. Real-time PCR targeting pmoA genes showed that the highest numbers of methanotrophs were present in surface sediments associated with the seep area. Phylogenetic analysis of pmoA sequences revealed that all phylotypes were novel and fell into two large clusters comprised of only marine sequences distantly related to the genera Methylococcus and Methylocaldum that were clearly divergent from terrestrial phylotypes. This study provides evidence for the existence of a novel microbial diversity and diverse aerobic methanotrophs that appear to constitute marine specialized lineages.

  7. Munidopsis lauensis Baba & de Saint Laurent, 1992 (Decapoda, Anomura, Munidopsidae), a newly recorded squat lobster from a cold seep in Taiwan.

    PubMed

    Lin, Chia-Wei; Tsuchida, Shinji; Lin, Saulwood; Berndt, Christian; Chan, Tin-Yam

    2013-11-18

    The squat lobster, Munidopsis lauensis Baba & de Saint Laurent, 1992, is recorded from Taiwan for the first time. This species was previously known only from deep-sea hydrothermal vents in the South-West Pacific but it was now found at a deep-sea cold seep site off southwestern Taiwan. The identity of the Taiwanese material is confirmed by comparison of sequences from the barcoding gene COI. Munidopsis lauensis can be easily separated from other congeners in Taiwanese waters by the eyes bearing a strong mesiodorsal spine and a small mesioventral spine, smooth carapace, fingers of the cheliped distally spooned and fixed finger without a denticulate carina on the distolateral margin. The discovery of this species in Taiwan increases the Munidopsis fauna of the island to 38 species. A color photograph and line drawings illustrating distinctive characters are provided for the Taiwanese material.

  8. First records of Lithodes longispina Sakai, 1971 (Crustacea: Decapoda: Anomura: Lithodidae) from southwestern Taiwan, including a site in the vicinity of a cold seep.

    PubMed

    Wang, Teng-Wei; Ahyong, Shane T; Chan, Tin-Yam

    2016-01-14

    Lithodid crabs (Lithodidae Samouelle, 1819), commonly known as king crabs, are frequent targets of commercial fishing worldwide with most of them living in deep water (Sakai 1971; Ahyong et al. 2010). Lithodes Latreille, 1806, is the second largest genus of lithodid crabs, currently including 29 species worldwide (Ahyong 2010). In Taiwanese waters, however, only two species, L. turritus Ortmann, 1892, and L. formosae Ahyong & Chan, 2010, have been reported (Wu et al. 1998; Ahyong & Chan 2010; Ahyong et al. 2010). We report herein the discovery of L. longispina Sakai, 1971, previously known reliably only from Japan (Sakai 1971; Ikeda 1998; Ahyong 2010), from off southwestern Taiwan, including a specimen collected in the vicinity of a cold seep.

  9. Use of 16S rRNA gene based clone libraries to assess microbial communities potentially involved in anaerobic methane oxidation in a Mediterranean cold seep.

    PubMed

    Heijs, Sander K; Haese, Ralf R; van der Wielen, Paul W J J; Forney, Larry J; van Elsas, Jan Dirk

    2007-04-01

    This study provides data on the diversities of bacterial and archaeal communities in an active methane seep at the Kazan mud volcano in the deep Eastern Mediterranean sea. Layers of varying depths in the Kazan sediments were investigated in terms of (1) chemical parameters and (2) DNA-based microbial population structures. The latter was accomplished by analyzing the sequences of directly amplified 16S rRNA genes, resulting in the phylogenetic analysis of the prokaryotic communities. Sequences of organisms potentially associated with processes such as anaerobic methane oxidation and sulfate reduction were thus identified. Overall, the sediment layers revealed the presence of sequences of quite diverse bacterial and archaeal communities, which varied considerably with depth. Dominant types revealed in these communities are known as key organisms involved in the following processes: (1) anaerobic methane oxidation and sulfate reduction, (2) sulfide oxidation, and (3) a range of (aerobic) heterotrophic processes. In the communities in the lowest sediment layer sampled (22-34 cm), sulfate-reducing bacteria and archaea of the ANME-2 cluster (likely involved in anaerobic methane oxidation) were prevalent, whereas heterotrophic organisms abounded in the top sediment layer (0-6 cm). Communities in the middle layer (6-22 cm) contained organisms that could be linked to either of the aforementioned processes. We discuss how these phylogeny (sequence)-based findings can support the ongoing molecular work aimed at unraveling both the functioning and the functional diversities of the communities under study.

  10. Use of 16S rRNA Gene Based Clone Libraries to Assess Microbial Communities Potentially Involved in Anaerobic Methane Oxidation in a Mediterranean Cold Seep

    PubMed Central

    Haese, Ralf R.; van der Wielen, Paul W. J. J.; Forney, Larry J.; van Elsas, Jan Dirk

    2007-01-01

    This study provides data on the diversities of bacterial and archaeal communities in an active methane seep at the Kazan mud volcano in the deep Eastern Mediterranean sea. Layers of varying depths in the Kazan sediments were investigated in terms of (1) chemical parameters and (2) DNA-based microbial population structures. The latter was accomplished by analyzing the sequences of directly amplified 16S rRNA genes, resulting in the phylogenetic analysis of the prokaryotic communities. Sequences of organisms potentially associated with processes such as anaerobic methane oxidation and sulfate reduction were thus identified. Overall, the sediment layers revealed the presence of sequences of quite diverse bacterial and archaeal communities, which varied considerably with depth. Dominant types revealed in these communities are known as key organisms involved in the following processes: (1) anaerobic methane oxidation and sulfate reduction, (2) sulfide oxidation, and (3) a range of (aerobic) heterotrophic processes. In the communities in the lowest sediment layer sampled (22–34 cm), sulfate-reducing bacteria and archaea of the ANME-2 cluster (likely involved in anaerobic methane oxidation) were prevalent, whereas heterotrophic organisms abounded in the top sediment layer (0–6 cm). Communities in the middle layer (6–22 cm) contained organisms that could be linked to either of the aforementioned processes. We discuss how these phylogeny (sequence)-based findings can support the ongoing molecular work aimed at unraveling both the functioning and the functional diversities of the communities under study. PMID:17431711

  11. Transcription, Signaling Receptor Activity, Oxidative Phosphorylation, and Fatty Acid Metabolism Mediate the Presence of Closely Related Species in Distinct Intertidal and Cold-Seep Habitats.

    PubMed

    Van Campenhout, Jelle; Vanreusel, Ann; Van Belleghem, Steven; Derycke, Sofie

    2015-12-03

    Bathyal cold seeps are isolated extreme deep-sea environments characterized by low species diversity while biomass can be high. The Håkon Mosby mud volcano (Barents Sea, 1,280 m) is a rather stable chemosynthetic driven habitat characterized by prominent surface bacterial mats with high sulfide concentrations and low oxygen levels. Here, the nematode Halomonhystera hermesi thrives in high abundances (11,000 individuals 10 cm(-2)). Halomonhystera hermesi is a member of the intertidal Halomonhystera disjuncta species complex that includes five cryptic species (GD1-5). GD1-5's common habitat is characterized by strong environmental fluctuations. Here, we compared the transcriptomes of H. hermesi and GD1, H. hermesi's closest relative. Genes encoding proteins involved in oxidative phosphorylation are more strongly expressed in H. hermesi than in GD1, and many genes were only observed in H. hermesi while being completely absent in GD1. Both observations could in part be attributed to high sulfide concentrations and low oxygen levels. Additionally, fatty acid elongation was also prominent in H. hermesi confirming the importance of highly unsaturated fatty acids in this species. Significant higher amounts of transcription factors and genes involved in signaling receptor activity were observed in GD1 (many of which were completely absent in H. hermesi), allowing fast signaling and transcriptional reprogramming which can mediate survival in dynamic intertidal environments. GC content was approximately 8% higher in H. hermesi coding unigenes resulting in differential codon usage between both species and a higher proportion of amino acids with GC-rich codons in H. hermesi. In general our results showed that most pathways were active in both environments and that only three genes are under natural selection. This indicates that also plasticity should be taken in consideration in the evolutionary history of Halomonhystera species. Such plasticity, as well as possible

  12. Evidence for chemoautotrophic symbiosis in a Mediterranean cold seep clam (Bivalvia: Lucinidae): comparative sequence analysis of bacterial 16S rRNA, APS reductase and RubisCO genes.

    PubMed

    Duperron, Sébastien; Fiala-Médioni, Aline; Caprais, Jean-Claude; Olu, Karine; Sibuet, Myriam

    2007-01-01

    Symbioses between lucinid clams (Bivalvia: Lucinidae) and autotrophic sulphide-oxidizing bacteria have mainly been studied in shallow coastal species, and information regarding deep-sea species is scarce. Here we study the symbiosis of a clam, resembling Lucinoma kazani, which was recently collected in sediment cores from new cold-seep sites in the vicinity of the Nile deep-sea fan, eastern Mediterranean, at depths ranging from 507 to 1691 m. A dominant bacterial phylotype, related to the sulphide-oxidizing symbiont of Lucinoma aequizonata, was identified in gill tissue by comparative 16S rRNA gene sequence analysis. A second phylotype, related to spirochete sequences, was identified twice in a library of 94 clones. Comparative analyses of gene sequences encoding the APS reductase alpha subunit and ribulose-1,5-bisphosphate carboxylase oxygenase support the hypothesis that the dominant symbiont can perform sulphide oxidation and autotrophy. Transmission electron micrographs of gills confirmed the dominance of sulphide-oxidizing bacteria, which display typical vacuoles, and delta(13)C values measured in gill and foot tissue further support the hypothesis for a chemoautotrophic-sourced host carbon nutrition.

  13. Methane release from sediment seeps to the atmosphere is counteracted by highly active Methylococcaceae in the water column of deep oligotrophic Lake Constance.

    PubMed

    Bornemann, Maren; Bussmann, Ingeborg; Tichy, Lucas; Deutzmann, Jörg; Schink, Bernhard; Pester, Michael

    2016-08-01

    Methane emissions from freshwater environments contribute substantially to global warming but are under strong control of aerobic methane-oxidizing bacteria. Recently discovered methane seeps (pockmarks) in freshwater lake sediments have the potential to bypass this control by their strong outgassing activity. Whether this is counteracted by pelagic methanotrophs is not well understood yet. We used a (3)H-CH4-radiotracer technique and pmoA-based molecular approaches to assess the activity, abundance and community structure of pelagic methanotrophs above active pockmarks in deep oligotrophic Lake Constance. Above profundal pockmarks, methane oxidation rates (up to 458 nmol CH4 l(-1) d(-1)) exceeded those of the surrounding water column by two orders of magnitude and coincided with maximum methanotroph abundances of 0.6% of the microbial community. Phylogenetic analysis indicated a dominance of members of the Methylococcaceae in the water column of both, pockmark and reference sites, with most of the retrieved sequences being associated with a water-column specific clade. Communities at pockmark and reference locations also differed in parts, which was likely caused by entrainment of sediment-hosted methanotrophs at pockmark sites. Our results show that the release of seep-derived methane to the atmosphere is counteracted by a distinct methanotrophic community with a pronounced activity throughout bottom waters. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Comparative population structure of two dominant species, Shinkaia crosnieri (Munidopsidae: Shinkaia) and Bathymodiolus platifrons (Mytilidae: Bathymodiolus), inhabiting both deep-sea vent and cold seep inferred from mitochondrial multi-genes.

    PubMed

    Shen, Yanjun; Kou, Qi; Chen, Weitao; He, Shunping; Yang, Mei; Li, Xinzheng; Gan, Xiaoni

    2016-06-01

    Deep-sea hydrothermal vents and cold seeps, limited environments without sunlight, are two types of extreme habitat for marine organisms. The differences between vents and cold seeps may facilitate genetic isolation and produce population heterogeneity. However, information on such chemosynthetic fauna taxa is rare, especially regarding the population diversity of species inhabiting both vents and cold seeps. In this study, three mitochondrial DNA fragments (the cytochrome c oxidase submit I (COI), cytochrome b gene (Cytb), and 16S) were concatenated as a mitochondrial concatenated dataset (MCD) to examine the genetic diversity, population structure, and demographic history of Shinkaia crosnieri and Bathymodiolus platifrons. The genetic diversity differences between vent and seep populations were statistically significant for S. crosnieri but not for B. platifrons. S. crosnieri showed less gene flow and higher levels of genetic differentiation between the vent and seep populations than B. platifrons. In addition, the results suggest that all the B. platifrons populations, but only the S. crosnieri vent populations, passed through a recent expansion or bottleneck. Therefore, different population distribution patterns for the two dominant species were detected; a pattern of population differentiation for S. crosnieri and a homogeneity pattern for B. platifrons. These different population distribution patterns were related to both extrinsic restrictive factors and intrinsic factors. Based on the fact that the two species were collected in almost identical or adjacent sampling sites, we speculated that the primary factors underlying the differences in the population distribution patterns were intrinsic. The historical demographics, dispersal ability, and the tolerance level of environmental heterogeneity are most likely responsible for the different distribution patterns.

  15. The Role of SRB on the Formation of Protodolomite and Monohydrocalcite: Insights from Cold Seep Simulation Experiment

    NASA Astrophysics Data System (ADS)

    Han, X.; Geesey, G.; Chen, X.

    2011-12-01

    Authigenic carbonates are very common at hydrocarbon seep sites on continental margin worldwide. Carbonate chimneys from the seep sites of the northeastern slope of the South China Sea are dominated by high-Mg calcite (HMC), with minor proto-dolomite, low-Mg calcite (LMC) and pyrite. HMC usually contains Mg less than 20 mol%, however, some of our samples contain HMC with Mg contents varied from 5-38mol%. The extreme high-Mg calcite approaches protodolomite composition; however, it still retains the structure of calcite. It has been known that the processes of anaerobic oxidation of methane (AOM) by consortia of archaea and sulfate reducing bacteria (SRB) are responsible for the precipitation of carbonates. To understand the formation mechanism of the unusual extreme high-Mg calcite as well as protodolomite in modern marine environment, we designed a set of mineral precipitation experiments simulating the pore water of the sulfate-methane transition zone of the seep sites of the South China Sea. The artificial pore water was enriched with formate, ammonia nitrogen and phosphate to achieve a C: N: P ratio of 106:12:1. Autoclave-sterilized nutrient enriched artificial pore water medium was inoculated with the SRB Desulfovibrio desulfuricans strain G-20 and incubated anaerobically at 25°C for 10 months. The precipitates that formed after incubation were analyzed using XRD, SEM and EDX and the concentration of key elements in the aqueous phase was determined using ICP-AES. Our results show that in the presence of SRBs, the pH of medium increased from 7.5 to 8.3 resulting in the precipitation of a mineral phase dominated by rhombohedra monohydrocalcite aggregates. In addition, spherical carbonate precipitates with Mg:Ca ratios varying from 0.16 to 0.98 suggest the presence of HMC and protodolomite. In the absence of SRB, the pH of the medium exhibited no significant change during incubation and only a small amount of aragonite and silica was produced: no

  16. High Diversity of Anaerobic Alkane-Degrading Microbial Communities in Marine Seep Sediments Based on (1-methylalkyl)succinate Synthase Genes

    PubMed Central

    Stagars, Marion H.; Ruff, S. Emil; Amann, Rudolf; Knittel, Katrin

    2016-01-01

    Alkanes comprise a substantial fraction of crude oil and are prevalent at marine seeps. These environments are typically anoxic and host diverse microbial communities that grow on alkanes. The most widely distributed mechanism of anaerobic alkane activation is the addition of alkanes to fumarate by (1-methylalkyl)succinate synthase (Mas). Here we studied the diversity of MasD, the catalytic subunit of the enzyme, in 12 marine sediments sampled at seven seeps. We aimed to identify cosmopolitan species as well as to identify factors structuring the alkane-degrading community. Using next generation sequencing we obtained a total of 420 MasD species-level operational taxonomic units (OTU0.96) at 96% amino acid identity. Diversity analysis shows a high richness and evenness of alkane-degrading bacteria. Sites with similar hydrocarbon composition harbored similar alkane-degrading communities based on MasD genes; the MasD community structure is clearly driven by the hydrocarbon source available at the various seeps. Two of the detected OTU0.96 were cosmopolitan and abundant while 75% were locally restricted, suggesting the presence of few abundant and globally distributed alkane degraders as well as specialized variants that have developed under specific conditions at the diverse seep environments. Of the three MasD clades identified, the most diverse was affiliated with Deltaproteobacteria. A second clade was affiliated with both Deltaproteobacteria and Firmicutes likely indicating lateral gene transfer events. The third clade was only distantly related to known alkane-degrading organisms and comprises new divergent lineages of MasD homologs, which might belong to an overlooked phylum of alkane-degrading bacteria. In addition, masD geneFISH allowed for the in situ identification and quantification of the target guild in alkane-degrading enrichment cultures. Altogether, these findings suggest an unexpectedly high number of yet unknown groups of anaerobic alkane degraders

  17. Development and field application of a 6-bottle serial gas-tight fluid sampler for collecting seafloor cold seep and hydrothermal vent fluids with autonomous operation capability

    NASA Astrophysics Data System (ADS)

    Wu, S.; Ding, K.; Yang, C.; Seyfried, W. E., Jr.; Tan, C.; Schaen, A. T.; Luhmann, A. J.

    2014-12-01

    A 6-bottle serial gas-tight sampler (so-called "six-shooter") was developed for application with deep-sea vent fluids. The new device is composed of a custom-made 6-channel valve manifold and six sampling bottles which are circularly distributed around the valve manifold. Each valve channel consists of a high-pressure titanium cartridge valve and a motor-driven actuator. A sampling snorkel is connected to the inlet of the manifold that delivers the incoming fluid to different bottles. Each sampling bottle has a 160 ml-volume chamber and an accumulator chamber inside where compressed nitrogen is used to maintain the sample at near in-situ pressure. An electronics chamber that is located at the center of the sampler is used to carry out all sampling operations, autonomously, if desired. The sampler is of a compact circular configuration with a diameter of 26 cm and a length of 54 cm. During the SVC cruise AT 26-12, the sampler was deployed by DSV2 Alvin at a cold seep site MC036 with a depth of 1090 m in the Gulf of Mexico. The sampler collected fluid samples automatically following the tidal cycle to monitor the potential impact of the tide cycle on the fluid chemistry of cold seep in a period of two day. During the cruise AT 26-17, the sampler was used with newly upgraded DSV2 Alvin three times at the hydrothermal vent sites along Axial Seamount and Main Endeavor Field on Juan de Fuca Ridge. During a 4-day deployment at Anemone diffuse site (Axial Caldera), the sampler was set to work in an autonomous mode to collect fluid samples according to the preset interval. During other dives, the sampler was manually controlled via ICL (Inductively Coupled Link) communication through the hull. Gas-tight fluid samples were collected from different hydrothermal vents with temperatures between 267 ℃ and 335 ℃ at the depth up to 2200 m. The field results indicate unique advantages of the design. It can be deployed in extended time period with remote operation or working

  18. Transcription, Signaling Receptor Activity, Oxidative Phosphorylation, and Fatty Acid Metabolism Mediate the Presence of Closely Related Species in Distinct Intertidal and Cold-Seep Habitats

    PubMed Central

    Van Campenhout, Jelle; Vanreusel, Ann; Van Belleghem, Steven; Derycke, Sofie

    2016-01-01

    Bathyal cold seeps are isolated extreme deep-sea environments characterized by low species diversity while biomass can be high. The Håkon Mosby mud volcano (Barents Sea, 1,280 m) is a rather stable chemosynthetic driven habitat characterized by prominent surface bacterial mats with high sulfide concentrations and low oxygen levels. Here, the nematode Halomonhystera hermesi thrives in high abundances (11,000 individuals 10 cm−2). Halomonhystera hermesi is a member of the intertidal Halomonhystera disjuncta species complex that includes five cryptic species (GD1-5). GD1-5’s common habitat is characterized by strong environmental fluctuations. Here, we compared the transcriptomes of H. hermesi and GD1, H. hermesi’s closest relative. Genes encoding proteins involved in oxidative phosphorylation are more strongly expressed in H. hermesi than in GD1, and many genes were only observed in H. hermesi while being completely absent in GD1. Both observations could in part be attributed to high sulfide concentrations and low oxygen levels. Additionally, fatty acid elongation was also prominent in H. hermesi confirming the importance of highly unsaturated fatty acids in this species. Significant higher amounts of transcription factors and genes involved in signaling receptor activity were observed in GD1 (many of which were completely absent in H. hermesi), allowing fast signaling and transcriptional reprogramming which can mediate survival in dynamic intertidal environments. GC content was approximately 8% higher in H. hermesi coding unigenes resulting in differential codon usage between both species and a higher proportion of amino acids with GC-rich codons in H. hermesi. In general our results showed that most pathways were active in both environments and that only three genes are under natural selection. This indicates that also plasticity should be taken in consideration in the evolutionary history of Halomonhystera species. Such plasticity, as well as possible

  19. Monitoring of Sedimentary Fluxes in Cold Environments: The SEDIBUD (Sediment Budgets in Cold Environments) Programme

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.

    2014-05-01

    Projected climate change in cold regions is expected to alter melt season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. Similarly, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. These effects will undoubtedly change surface environments in cold regions and alter the fluxes of sediments, nutrients and solutes, but the absence of quantitative data and coordinated geomorphic process monitoring and analysis to understand the sensitivity of the Earth surface environment is acute in cold climate environments. The International Association of Geomorphologists` (I.A.G. / A.I.G.) SEDIBUD (Sediment Budgets in Cold Environments) Program (2005 - 2017) is addressing this existing key knowledge gap. The central research question of this global group of scientists is to: Assess and model the contemporary sedimentary fluxes in cold climates, with emphasis on both particulate and dissolved components. Research carried out at each of the ca. 50 defined SEDIBUD key test sites varies by program, logistics and available resources, but typically represent interdisciplinary collaborations of geomorphologists, hydrologists, ecologists, permafrost scientists and glaciologists. SEDIBUD has developed manuals and protocols (SEDIFLUX Manual) with a key set of primary surface process monitoring and research data requirements to incorporate results from these diverse projects and allow coordinated quantitative analysis across the program. Defined SEDIBUD key tasks for the coming years include (i) The continued generation and compilation of comparable longer-term datasets on contemporary sedimentary fluxes and sediment yields from SEDIBUD key test sites worldwide, (ii) The continued extension of the SEDIBUD metadata database with these datasets, (iii) The testing of defined SEDIBUD hypotheses (available

  20. Authigenic carbonates from an active cold seep of the northern South China Sea: New insights into fluid sources and past seepage activity

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Chen, Duofu

    2015-12-01

    Site F (also named Formosa ridge) represents the most vigorous cold seep on the northern South China Sea continental slope. In order to constrain the fluid sources and intensities of seepage, we investigated the petrography, mineralogy, stable carbon and oxygen isotopic compositions, element geochemistry and radiocarbon dating of authigenic carbonate rocks retrieved from the seafloor. Carbonate rocks mainly occurred as crusts, nodules, and nodular masses incorporated in carbonate breccias. The carbonates were comprised mainly of high-Mg calcite and aragonite. The δ13C of authigenic carbonate varied from -55.3‰ to -34.3‰ (mean: -48.5‰; n=47) vs. V-PDB, suggesting biogenic methane is the dominant carbon source fuelling the system. The δ18OCarbonate values were from +3.6‰ to +4.8‰ (mean: +3.9‰; n=47). The observed 18O-enrichement in relation to calculated equilibrium values in the carbonates probably reflects dissolution of gas hydrates. Combination of seafloor observations and the obtained AMS 14C ages suggest that (1) initiation of methane seepage from at least 10.6 ka ago; (2) environmental conditions may have been favorable for enhanced fluid seepage around 6 ka BP and (3) relatively low intensity of seepage from 2 ka BP till today.

  1. Halobacillus profundi sp. nov. and Halobacillus kuroshimensis sp. nov., moderately halophilic bacteria isolated from a deep-sea methane cold seep.

    PubMed

    Hua, Ngoc-Phuc; Kanekiyo, Atsuko; Fujikura, Katsunori; Yasuda, Hisato; Naganuma, Takeshi

    2007-06-01

    Two Gram-positive, rod-shaped, moderately halophilic bacteria were isolated from a deep-sea carbonate rock at a methane cold seep in Kuroshima Knoll, Japan. These bacteria, strains IS-Hb4(T) and IS-Hb7(T), were spore-forming and non-motile. They were able to grow at temperatures as low as 9 degrees C and hydrostatic pressures up to 30 MPa. Based on high sequence similarity of their 16S rRNA genes to those of type strains of the genus Halobacillus, from 96.4 % (strain IS-Hb7(T) to Halobacillus halophilus NCIMB 9251(T)) to 99.4 % (strain IS-Hb4(T) to Halobacillus dabanensis D-8(T)), the strains were shown to belong to this genus. DNA-DNA relatedness values of 49.5 % and 1.0-33.0 %, respectively, were determined between strains IS-Hb4(T) and IS-Hb7(T) and between these strains and other Halobacillus type strains. Both strains showed the major menaquinone MK7 and L-orn-D-Asp cell-wall peptidoglycan type. Straight-chain C(16 : 0), unsaturated C(16 : 1)omega7c alcohol and C(18 : 1)omega7c and cyclopropane C(19 : 0) cyc fatty acids were predominant in both strains. The DNA G+C contents of IS-Hb4(T) and IS-Hb7(T) were respectively 43.3 and 42.1 mol%. Physiological and biochemical analyses combined with DNA-DNA hybridization results allowed us to place strains IS-Hb4(T) (=JCM 14154(T)=DSM 18394(T)) and IS-Hb7(T) (=JCM 14155(T)=DSM 18393(T)) in the genus Halobacillus as the respective type strains of the novel species Halobacillus profundi sp. nov. and Halobacillus kuroshimensis sp. nov.

  2. Diversity, relative abundance and metabolic potential of bacterial endosymbionts in three Bathymodiolus mussel species from cold seeps in the Gulf of Mexico.

    PubMed

    Duperron, Sébastien; Sibuet, Myriam; MacGregor, Barbara J; Kuypers, Marcel M M; Fisher, Chuck R; Dubilier, Nicole

    2007-06-01

    Cold seeps in the Gulf of Mexico are often dominated by mussels of the genus Bathymodiolus that harbour symbiotic bacteria in their gills. In this study, we analysed symbiont diversity, abundance and metabolic potential in three mussel species from the northern Gulf of Mexico: Bathymodiolus heckerae from the West Florida Escarpment, Bathymodiolus brooksi from Atwater Valley and Alaminos Canyon, and 'Bathymodiolus' childressi, which co-occurs with B. brooksi in Alaminos Canyon. Comparative 16S rRNA sequence analysis confirmed a single methanotroph-related symbiont in 'B.' childressi and a dual symbiosis with a methanotroph- and thiotroph-related symbiont in B. brooksi. A previously unknown diversity of four co-occurring symbionts was discovered in B. heckerae: a methanotroph, two phylogenetically distinct thiotrophs and a methylotroph-related phylotype not previously described from any marine invertebrate symbiosis. A gene characteristic of methane-oxidzing bacteria, pmoA, was identified in all three mussel species confirming the methanotrophic potential of their symbionts. Stable isotope analyses of lipids and whole tissue also confirmed the importance of methanotrophy in the carbon nutrition of all of the mussels. Analyses of absolute and relative symbiont abundance in B. heckerae and B. brooksi using fluorescence in situ hybridization (FISH) and rRNA slot blot hybridization indicated a clear dominance of methanotrophic over thiotrophic symbionts in their gill tissues. A site-dependent variability in total symbiont abundance was observed in B. brooksi, with specimens from Alaminos Canyon harbouring much lower densities than those from Atwater Valley. This shows that symbiont abundance is not species-specific but can vary considerably between populations.

  3. A unique Fe-rich carbonate chimney associated with cold seeps in the Northern Okinawa Trough, East China Sea

    NASA Astrophysics Data System (ADS)

    Sun, Zhilei; Wei, Helong; Zhang, Xunhua; Shang, Luning; Yin, Xijie; Sun, Yunbao; Xu, Lei; Huang, Wei; Zhang, Xianrong

    2015-01-01

    The East China Sea is an important marginal sea of the Western Pacific Ocean, from which natural gas hydrate sample has not been acquired so far. Recently, copious carbonate chimneys have been discovered in turbidite deposits in the olistostrome zone located on the west slope of the northern section of Okinawa Trough. Here, the petrology, geochemistry and chronology of an iron-rich carbonate chimney were characterized, confirming a close relationship between its formation and the dissociation of natural gas hydrate beneath the chimney in OT. A distinctive relationship has been observed between goethite and total carbonate contents along with a negative correlation between Fe and Ca contents. Conversely, abundant Fe accumulated on carbonate substrate by mineralized microorganisms. The δ13C values of the chimney wall were from -27.56 to -43.66‰ (average: -37.18‰, V-PDB), implying anaerobic oxidation of methane (AOM) as a predominant controlling factor on carbonate precipitation. As no pyrite and organic residues were identified in the iron-rich chimney, it was assumed that AOM was coupled to the iron reduction reaction at least to some extent during the chimney growth owing to the local deficiency of sulfate supply. The δ56Fe values of bulk chimney wall (ranging from -0.316‰ to -0.023‰, average -0.134‰) suggest mass and isotope exchanges between the chimney and ambient environment during its growth history, whereas the enrichment of δ18O of the carbonate implies these carbonate sourcing from hydrate dissociation underlying our sampling site. This assumption has been supported by a distinct bottom simulation reflector (BSR) and a well-developed fault system beneath the sampling site. This is the first report of cold seepage inside the OT and the identified iron-dependent AOM has shed a new light to the Carbon cycle related to the marine methane oxidation, particularly before the Great Oxidation Event ~2.45 Ga ago.

  4. Microbial methane turnover at Marmara Sea cold seeps: a combined 16S rRNA and lipid biomarker investigation.

    PubMed

    Chevalier, N; Bouloubassi, I; Birgel, D; Taphanel, M-H; López-García, P

    2013-01-01

    Lipid biomarkers and their stable carbon isotopic composition, as well as 16S rRNA gene sequences, were investigated in sediment cores from active seepage zones in the Sea of Marmara (Turkey) located on the active North Anatolian Fault, to assess processes associated with methane turnover by indigenous microbial communities. Diagnostic (13) C-depleted archaeal lipids of anaerobic methane oxidizers were only found in one core from the South of Çinarcik Basin and consist mainly of archaeol, sn-2 hydroxyarchaeol and various unsaturated pentamethylicosenes. Concurrently, abundant fatty acids (FAs) and a substantial amount of monoalkylglycerolethers (MAGEs), assigned to sulphate-reducing bacteria, were detected with strong (13) C-depletions. Both microbial lipids and their δ(13) C values suggest that anaerobic oxidation of methane with sulphate reduction (AOM/SR) occurs, specially in the 10- to 12-cm depth interval. Lipid biomarker results accompanied by 16S rRNA-based microbial diversity analyses showed that ANME-2 (ANME-2a and -2c) archaea and Desulfosarcina/Desulfococcus and Desulfobulbus deltaproteobacterial clades are the major AOM assemblages, which indicate a shallow AOM community at high methane flux. Apart from the typical AOM lipid biomarker pattern, a (13) C-depleted diunsaturated hydrocarbon, identified as 7,14-tricosadiene, occurred in the inferred maximum AOM interval at 10-12 cm depth. Its isotopic fingerprint implies that its microbial precursor occurs in close association with the AOM communities. Interestingly, the presence of 7,14-tricosadiene coincides with the presence of the so-far uncultured bacterial Candidate Division JS1, often detected in AOM areas. We propose the hypothesis that the JS1 bacterial group could be the potential source of (13) C-depleted tricosadiene. Future testing of this hypothesis is essential to fully determine the role of this bacterial group in AOM. © 2012 Blackwell Publishing Ltd.

  5. Changing composition of microbial communities indicates seepage fluid difference of the Thuwal Seeps in the Red Sea.

    PubMed

    Yang, Bo; Zhang, Weipeng; Tian, Renmao; Wang, Yong; Qian, Pei-Yuan

    2015-08-01

    Cold seeps are unique ecosystems that are generally characterized by high salinity and reducing solutions. Seepage fluid, the major water influx of this system, contains hypersaline water, sediment pore water, and other components. The Thuwal cold seeps were recently discovered on the continental margin of the Red Sea. Using 16S rRNA gene pyro-sequencing technology, microbial communities were investigated by comparing samples collected in 2011 and 2013. The results revealed differences in the microbial communities between the two sampling times. In particular, a significantly higher abundance of Marine Group I (MGI) Thaumarchaeota was coupled with lower salinity in 2013. In the brine pool, the dominance of Desulfobacterales in 2011 was supplanted by MGI Thaumarchaeota in 2013, perhaps due to a reduced supply of hydrogen sulfide from the seepage fluid. Collectively, this study revealed a difference in water components in this ecosystem between two sampling times. The results indicated that the seawater in this cold seep displayed a greater number of characteristics of normal seawater in 2013 than in 2011, which might represent the dominant driving force for changes in microbial community structures. This is the first study to provide a temporal comparison of the microbial biodiversity of a cold seep ecosystem in the Red Sea.

  6. Using Multi-Disciplinary Data to Compile a Hydrocarbon Budget for GC600, a Natural Seep in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    MacDonald, I. R.; Johansen, C.; Marty, E.; Natter, M.; Silva, M.; Hill, J. C.; Viso, R. F.; Lobodin, V.; Diercks, A. R.; Woolsey, M.; Macelloni, L.; Shedd, W. W.; Joye, S. B.; Abrams, M.

    2016-12-01

    Fluid exchange between the deep subsurface and the overlying ocean and atmosphere occurs at hydrocarbon seeps along continental margins. Seeps are key features that alter the seafloor morphology and geochemically affect the sediments that support chemosynthetic communities. However, the dynamics and discharge rates of hydrocarbons at cold seeps remain largely unconstrained. Here we merge complementary geochemical (oil fingerprinting), geophysical (seismic, subbottom, backscatter, multibeam) and video/imaging (Video Time Lapse Camera, DSV ALVIN video) data sets to constrain pathways and magnitudes of hydrocarbon fluxes from the source rock to the seafloor at a well-studied, prolific seep site in the Northern Gulf of Mexico (GC600). Oil fingerprinting showed compositional similarities for samples from the following collections: the reservoir, an active vent, and the sea-surface. This was consistent with reservoir structures and pathways identified in seismic data. Video data, which showed the spatial distribution of seep indicators such as bacteria mats, or hydrate outcrops at the sediment interface, were combined with known hydrocarbon fluxes from the literature and used to quantify the total hydrocarbon fluxes in the seep domain. Using a systems approach, we combined data sets and published values at various scales and resolutions to compile a preliminary hydrocarbon budget for the GC600 seep site. Total estimated in-flow of hydrocarbons was 2.07 x 109 mol/yr. The combined total of out-flow and sequestration amounted to 7.56 x 106 mol/yr leaving a potential excess (in-flow - out-flow) of 2.06 x 109 mol/yr. Thus quantification of the potential out-flow from the seep domains based on observable processes does not equilibrate with the theoretical inputs from the reservoir. Processes that might balance this budget include accumulation of gas hydrate and sediment free-gas, as well as greater efficiency of biological sinks.

  7. Chemistry and mineralogy of pyrite-enriched sediments at a passive margin sulfide brine seep: abyssal Gulf of Mexico

    USGS Publications Warehouse

    Commeau, R.F.; Paull, C.K.; Commeau, J.A.; Poppe, L.J.

    1987-01-01

    Pyrite is rapidly accumulating at the contact between the Cretaceous limestones of the Florida Platform and the hemipelagic sediments of the abyssal Gulf of Mexico. Sediments sampled with the submersible "Alvin" in 3266 m of water are associated with a dense community of organisms that depend on chemosynthetic primary production as a food source. Analysis of the chemistry, mineralogy, and textural composition of these sediments indicate that iron sulfide mineralization is occurring at the seafloor within an anoxic micro-habitat sustained by the advection of hydrogen sulfide-charged saline brines from the adjacent platform. The chemosynthetic bacteria that directly overlie the sediments oxidize hydrogen sulfide for energy and provide elemental sulfur that reacts with iron monosulfide to form some of the pyrite. The sediments are mixtures of pyrite (??? 30 wt.%), BaSr sulfates (??? 4 wt.%), clays, and locally derived biogenic carbonates and are progressively being cemented by iron sulfides. Oxidation of hydrogen sulfide produces locally acidic conditions that corrode the adjacent limestones. Potential sources of S, H2S, Fe, Ba, and Sr are discussed. ?? 1987.

  8. A recent investigation of gas hydrate as a factor in northern Cascadia accretionary margin frontal ridge slope failures and cold seep biogeochemistry

    NASA Astrophysics Data System (ADS)

    Haacke, R.; Riedel, M.; Pohlman, J.; Rose, K.; Lapham, L.; Hamilton, T. S.; Enkin, R.; Spence, G.; Hyndman, R.

    2008-12-01

    In August 2008, a research expedition was conducted on the n. Cascadia margin by the Geological Survey of Canada (GSC) as part of the Earth Science Sector, Natural Gas Hydrate Program, Natural Resources Canada (NRCan). This collaboration included researchers from several universities as well as Canadian and U.S. government agencies. The primary objective was to determine the impact of gas hydrate on slope stability along the frontal ridges of the N. Cascadia accretionary wedge. Multibeam bathymetry data indicate numerous slope collapse features along the frontal ridges. To constrain the cause and timing of the collapse features, sedimentological, physical property and geochemical studies were conducted at several slump areas. Four cores were collected from within the headwall, apron and sole of the slumped material of 'Lopez Slide', a failure area detected prior to IODP Expedition 311. Directly south of Lopez Slide at a slump feature named 'Slipstream Slide', a 5-core transect extended from the headwall scarp to the toe of the slide deposits. Slipstream Slide is a series of en echelon box-like slump blocks bounded by transverse faults that cross-cut that frontal ridge. One additional core from a slump-feature further south (Chunk Slide) was also recovered. Onboard analyses suggest that the slump occurrences are not related to the last mega-thrust earthquake that occurred at the N. Cascadia subduction zone in January 1700. However, the slumps could have been triggered by earlier such earthquakes. Further analyses and age determinations are underway to confirm the linkages between slumps and the mega-thrust earthquake cycle and other possible trigger mechanisms such as eustatic sea level changes. The secondary objective of the expedition was a multidisciplinary program that included microbiological, geochemical, geophysical and sedimentological studies designed to advance our understanding of the environmental factors that control methane fluxes and oxidation at cold

  9. Unusual novel n-4 polyunsaturated fatty acids in cold-seep mussels (Bathymodiolus japonicus and Bathymodiolus platifrons), originating from symbiotic methanotrophic bacteria.

    PubMed

    Saito, Hiroaki

    2008-07-25

    Novel fatty acids originated from the two cold-seep mussels Bathymodiolus japonicus and Bathymodiolus platifrons, which host methane-oxidizing bacteria, were determined by using gas chromatography-mass spectrometry analysis of the 4,4-dimethyloxazoline derivatives. The major polyunsaturated fatty acids (PUFAs) in the two mussels belong to unusual n-4 and n-7 methylene interrupted PUFAs, such as 18:3 n-7,10,13 (Delta5,8,11-18:3), 18:4 n-4,7,10,13 (Delta5,8,11,14-18:4), 20:3n-7,10,13 (Delta7,10,13-20:3), 20:4n-4,7,10,13 (Delta7,10,13,16-20:4), and 21:4n-7,10,13,16 (Delta5,8,11,14-20:4). The similarity of fatty acids in the two Bathymodiolus species produced by the symbiotic bacteria, indicate occurrence of highly homologous mussel symbionts. In contrast to the lipids of shallow-water mussel Mytilus galloprovincialis, which contains photosynthetic n-3 PUFAs, the two Bathymodiolus mussels were lacking in docosahexaenoic acid and icosapentaenoic acid even though they are marine animals. These findings suggest the Bathymodiolus species survive independently of photosynthetic products, similar to the Calyptogena clams, which house sulfur-oxidizing bacteria and whose lipid contains n-4 non-methylene interrupted PUFAs (20:3n-4,7,15 (Delta5,13,16-20:3), 20:4n-1,4,7,15 (Delta5,13,16,19-20:4), and 21:3n-4,7,16 (Delta5,14,17-20:3)). The similarity in n-4 fatty acids between the mussels and the clam suggests that these bivalves depend on analogous n-4 family PUFAs and that the n-4 PUFA family is a characteristic of all vent bivalves depending on geothermal energy. The differences of the n-4 PUFAs between the mussels and the clam suggest a generic specificity of symbiotic bacteria and differences in lipid physiology between thiotrophic and methanotrophic symbionts. Such a highly diversified variety of n-4 family PUFAs in the mussels and the clam under different environments presumably increase the great potential of the chemosynthetic bacteria.

  10. Seeps regulate stream nitrate concentration in a forested Appalachian catchment.

    PubMed

    O'Driscoll, Michael A; DeWalle, David R

    2010-01-01

    Surface seeps can be defined as locations where upwelling ground water saturates the surface for most of the year and excess ground water can be delivered to the stream channel via surface flowpaths. If a stream is predominantly fed by seeps, then ground water added to the stream via these surface flowpaths may result in reduced interactions with the subsurface riparian zone. It is generally believed that seep ground water that upwells and then flows along surface flowpaths can be subject to diminished denitrification and biologic uptake processes. Seep effects on stream nitrate (NO(3)) concentration were studied in Baldwin Creek (5.35 km(2)), southwestern Pennsylvania. Nitrate retention within seep zones was evaluated over a 1-yr period (May 2002-2003) using a monthly, nested (top and bottom of seep) sampling approach along 15 individual seeps. Seep samples were analyzed for NO(3)-N, NH(3)-N, and dissolved organic carbon, along with stream waters and streamflow measurements at seven stream stations. Seeps were generally NO(3) sinks with concentrations decreasing downseep: 31% median annual reduction and 73% maximum monthly reduction. During cold and wet periods, seeps frequently behaved as NO(3) sources to the stream (NO(3) concentrations increased or remained constant downseep). Seep temperature and discharge were related to seasonal variability in seep NO(3) retention. Seasonal variations in stream NO(3) concentration have been attributed to upland soil and vegetation processes in numerous watersheds. At Baldwin Creek, seep NO(3) processing regulated the seasonal variability of stream NO(3) concentrations. These results suggest that seeps provide important water quality functions and can modulate the effects of elevated regional N deposition in Appalachian catchments.

  11. Intraskeletal isotopic and elemental chemistry of chemosymbiont-bearing calyptogenid bivalves from an active methane seep: Implications for seep dynamics and reconstruction

    NASA Astrophysics Data System (ADS)

    Schellenberg, S. A.; Gale, C. N.; Barry, J. P.

    2005-12-01

    δ13C -enrichment through preferential 12C uptake by bacterial productivity. The decreasing δ13C values toward the cold-seep center likely reflect increasing 12C-enriched contributions of C. kilmeri-respired CO2 and/or pore-water DIC to the calcification fluid. Physiological principles would suggest an adaptive peak for C. kilmeri where (1) dissolved sulfide supply from pore-waters is optimal for bacterial productivity, but non-toxic for the bivalve, and (2) dissolved oxygen supply at the sediment-water interface is sufficient for bivalve respiration. Specimens from this adaptive peak would likely have the highest productivity:respiration ratios and exhibit the fastest tissue and shell growth-rates. While tempting to interpret this adaptive peak as proximal to the outer-seep location based on its higher Sr/Ca (i.e., faster shell growth driven by higher productivity) and higher δ13C (i.e., least affected by sulfide-rich pore-waters depleted in δ13C), the available geochemical and environmental constraints provide insufficient confidence for a unique interpretation. In contrast, δ18O values show no significant differences among seep locations, and are consistent with isotopic equilibrium precipitation from seawater DIC.

  12. Molecular Characterization of Potential Nitrogen Fixation by Anaerobic Methane-Oxidizing Archaea in the Methane Seep Sediments at the Number 8 Kumano Knoll in the Kumano Basin, Offshore of Japan▿ †

    PubMed Central

    Miyazaki, Junichi; Higa, Ryosaku; Toki, Tomohiro; Ashi, Juichiro; Tsunogai, Urumu; Nunoura, Takuro; Imachi, Hiroyuki; Takai, Ken

    2009-01-01

    The potential for microbial nitrogen fixation in the anoxic methane seep sediments in a mud volcano, the number 8 Kumano Knoll, was characterized by molecular phylogenetic analyses. A total of 111 of the nifH (a gene coding a nitrogen fixation enzyme, Fe protein) clones were obtained from different depths of the core sediments, and the phylogenetic analysis of the clones indicated the genetic diversity of nifH genes. The predominant group detected (methane seep group 2), representing 74% of clonal abundance, was phylogenetically related to the nifH sequences obtained from the Methanosarcina species but was most closely related to the nifH sequences potentially derived from the anoxic methanotrophic archaea (ANME-2 archaea). The recovery of the nif gene clusters including the nifH sequences of the methane seep group 2 and the subsequent reverse transcription-PCR detection of the nifD and nifH genes strongly suggested that the genetic components of the gene clusters would be operative for the in situ assimilation of molecular nitrogen (N2) by the host microorganisms. DNA-based quantitative PCR of the archaeal 16S rRNA gene, the group-specific mcrA (a gene encoding the methyl-coenzyme M reductase α subunit) gene, and the nifD and nifH genes demonstrated the similar distribution patterns of the archaeal 16S rRNA gene, the mcrA groups c-d and e, and the nifD and nifH genes through the core sediments. These results supported the idea that the anoxic methanotrophic archaea ANME-2c could be the microorganisms hosting the nif gene clusters and could play an important role in not only the in situ carbon (methane) cycle but also the nitrogen cycle in subseafloor sediments. PMID:19783748

  13. Environmental effects of submarine seeping natural gas

    NASA Astrophysics Data System (ADS)

    Dando, P. R.; Hovland, M.

    1992-10-01

    It is suspected that most shallow reservoirs of natural gas vent to the surface to some degree. This seeping may be through diffusion of dissolved gas or by a flow of gas bubbles which entrain interstitial water during the rise through the sediments to the surface. Methane bubbles dissolved other gases, notably hydrogen sulphide and carbon dioxide, during their ascent. Under suitable temperature-pressure conditions gas hydrates may be formed close to or at the seabed Black suphide-rich sediments and mats of sulphur oxidizing bacteria are frequently observed close to the sediments surface at seep sites, including a sharp oxic/anoxic boundary. Animal species associated with these gas seeps include both species which obtain nutrition from symbiotic methane-oxidizing bacteria and species with symbolic sulphur-oxidizing bacteria. It is suspected that at some microseepage an enhanced biomass of meiofauna and macrofauna is supported by a food chain based on free-living and symbiotic sulphur-oxidizing and methane-oxidizing bacteria. The most common seep-related features of sea floor topography are local depressions including pockmark craters. Winnowing of the sediment during their creation leads to an accumulation of larger detritis in the depressions. Where the deprssions overlies salt diapirs they may be filled with hypersaline solutions. In some areas dome-shaped features are associated with seepage and these may be colonized by coral reefs. Other reefs, "hard-grounds", columnar and disc-shaped protrusions, all formed of carbonate-cemented sediments, are common on the sea floor in seep areas. Much of the carbonate appears to be derived from carbon dioxide formed as a result of methane oxidation. The resulting hard-bottoms on the sea floor are often colonized by species not found on the neighboring soft-bottoms. As a result seep areas may be characterized by the presence of a rich epifauna.

  14. Methane seep carbonates yield clumped isotope signatures out of equilibrium with formation temperatures

    SciTech Connect

    Loyd, S. J.; Sample, J.; Tripati, R. E.; Defliese, W. F.; Brooks, K.; Hovland, M.; Torres, M.; Marlow, J.; Hancock, L. G.; Martin, R.; Lyons, T.; Tripati, A. E.

    2016-07-22

    Here, methane cold seep systems typically exhibit extensive buildups of authigenic carbonate minerals, resulting from local increases in alkalinity driven by methane oxidation. Here, we demonstrate that modern seep authigenic carbonates exhibit anomalously low clumped isotope values (Δ47), as much as ~0.2‰ lower than expected values. In modern seeps, this range of disequilibrium translates into apparent temperatures that are always warmer than ambient temperatures, by up to 50 °C. We examine various mechanisms that may induce disequilibrium behaviour in modern seep carbonates, and suggest that the observed values result from several factors including kinetic isotopic effects during methane oxidation, mixing of inorganic carbon pools, pH effects and rapid precipitation. Ancient seep carbonates studied here also exhibit potential disequilibrium signals. Ultimately, these findings indicate the predominance of disequilibrium clumped isotope behaviour in modern cold seep carbonates that must be considered when characterizing environmental conditions in both modern and ancient cold seep settings.

  15. Methane seep carbonates yield clumped isotope signatures out of equilibrium with formation temperatures.

    PubMed

    Loyd, S J; Sample, J; Tripati, R E; Defliese, W F; Brooks, K; Hovland, M; Torres, M; Marlow, J; Hancock, L G; Martin, R; Lyons, T; Tripati, A E

    2016-07-22

    Methane cold seep systems typically exhibit extensive buildups of authigenic carbonate minerals, resulting from local increases in alkalinity driven by methane oxidation. Here, we demonstrate that modern seep authigenic carbonates exhibit anomalously low clumped isotope values (Δ47), as much as ∼0.2‰ lower than expected values. In modern seeps, this range of disequilibrium translates into apparent temperatures that are always warmer than ambient temperatures, by up to 50 °C. We examine various mechanisms that may induce disequilibrium behaviour in modern seep carbonates, and suggest that the observed values result from several factors including kinetic isotopic effects during methane oxidation, mixing of inorganic carbon pools, pH effects and rapid precipitation. Ancient seep carbonates studied here also exhibit potential disequilibrium signals. Ultimately, these findings indicate the predominance of disequilibrium clumped isotope behaviour in modern cold seep carbonates that must be considered when characterizing environmental conditions in both modern and ancient cold seep settings.

  16. Methane seep carbonates yield clumped isotope signatures out of equilibrium with formation temperatures

    NASA Astrophysics Data System (ADS)

    Loyd, S. J.; Sample, J.; Tripati, R. E.; Defliese, W. F.; Brooks, K.; Hovland, M.; Torres, M.; Marlow, J.; Hancock, L. G.; Martin, R.; Lyons, T.; Tripati, A. E.

    2016-07-01

    Methane cold seep systems typically exhibit extensive buildups of authigenic carbonate minerals, resulting from local increases in alkalinity driven by methane oxidation. Here, we demonstrate that modern seep authigenic carbonates exhibit anomalously low clumped isotope values (Δ47), as much as ~0.2‰ lower than expected values. In modern seeps, this range of disequilibrium translates into apparent temperatures that are always warmer than ambient temperatures, by up to 50 °C. We examine various mechanisms that may induce disequilibrium behaviour in modern seep carbonates, and suggest that the observed values result from several factors including kinetic isotopic effects during methane oxidation, mixing of inorganic carbon pools, pH effects and rapid precipitation. Ancient seep carbonates studied here also exhibit potential disequilibrium signals. Ultimately, these findings indicate the predominance of disequilibrium clumped isotope behaviour in modern cold seep carbonates that must be considered when characterizing environmental conditions in both modern and ancient cold seep settings.

  17. Methane seep carbonates yield clumped isotope signatures out of equilibrium with formation temperatures

    PubMed Central

    Loyd, S. J.; Sample, J.; Tripati, R. E.; Defliese, W. F.; Brooks, K.; Hovland, M.; Torres, M.; Marlow, J.; Hancock, L. G.; Martin, R.; Lyons, T.; Tripati, A. E.

    2016-01-01

    Methane cold seep systems typically exhibit extensive buildups of authigenic carbonate minerals, resulting from local increases in alkalinity driven by methane oxidation. Here, we demonstrate that modern seep authigenic carbonates exhibit anomalously low clumped isotope values (Δ47), as much as ∼0.2‰ lower than expected values. In modern seeps, this range of disequilibrium translates into apparent temperatures that are always warmer than ambient temperatures, by up to 50 °C. We examine various mechanisms that may induce disequilibrium behaviour in modern seep carbonates, and suggest that the observed values result from several factors including kinetic isotopic effects during methane oxidation, mixing of inorganic carbon pools, pH effects and rapid precipitation. Ancient seep carbonates studied here also exhibit potential disequilibrium signals. Ultimately, these findings indicate the predominance of disequilibrium clumped isotope behaviour in modern cold seep carbonates that must be considered when characterizing environmental conditions in both modern and ancient cold seep settings. PMID:27447820

  18. Global dispersion and local diversification of the methane seep microbiome.

    PubMed

    Ruff, S Emil; Biddle, Jennifer F; Teske, Andreas P; Knittel, Katrin; Boetius, Antje; Ramette, Alban

    2015-03-31

    Methane seeps are widespread seafloor ecosystems shaped by the emission of gas from seabed reservoirs. The microorganisms inhabiting methane seeps transform the chemical energy in methane to products that sustain rich benthic communities around the gas leaks. Despite the biogeochemical relevance of microbial methane removal at seeps, the global diversity and dispersion of seep microbiota remain unknown. Here we determined the microbial diversity and community structure of 23 globally distributed methane seeps and compared these to the microbial communities of 54 other seafloor ecosystems, including sulfate-methane transition zones, hydrothermal vents, coastal sediments, and deep-sea surface and subsurface sediments. We found that methane seep communities show moderate levels of microbial richness compared with other seafloor ecosystems and harbor distinct bacterial and archaeal taxa with cosmopolitan distribution and key biogeochemical functions. The high relative sequence abundance of ANME (anaerobic methanotrophic archaea), as well as aerobic Methylococcales, sulfate-reducing Desulfobacterales, and sulfide-oxidizing Thiotrichales, matches the most favorable microbial metabolisms at methane seeps in terms of substrate supply and distinguishes the seep microbiome from other seafloor microbiomes. The key functional taxa varied in relative sequence abundance between different seeps due to the environmental factors, sediment depth and seafloor temperature. The degree of endemism of the methane seep microbiome suggests a high local diversification in these heterogeneous but long-lived ecosystems. Our results indicate that the seep microbiome is structured according to metacommunity processes and that few cosmopolitan microbial taxa mediate the bulk of methane oxidation, with global relevance to methane emission in the ocean.

  19. Global dispersion and local diversification of the methane seep microbiome

    PubMed Central

    Ruff, S. Emil; Biddle, Jennifer F.; Teske, Andreas P.; Knittel, Katrin; Boetius, Antje

    2015-01-01

    Methane seeps are widespread seafloor ecosystems shaped by the emission of gas from seabed reservoirs. The microorganisms inhabiting methane seeps transform the chemical energy in methane to products that sustain rich benthic communities around the gas leaks. Despite the biogeochemical relevance of microbial methane removal at seeps, the global diversity and dispersion of seep microbiota remain unknown. Here we determined the microbial diversity and community structure of 23 globally distributed methane seeps and compared these to the microbial communities of 54 other seafloor ecosystems, including sulfate–methane transition zones, hydrothermal vents, coastal sediments, and deep-sea surface and subsurface sediments. We found that methane seep communities show moderate levels of microbial richness compared with other seafloor ecosystems and harbor distinct bacterial and archaeal taxa with cosmopolitan distribution and key biogeochemical functions. The high relative sequence abundance of ANME (anaerobic methanotrophic archaea), as well as aerobic Methylococcales, sulfate-reducing Desulfobacterales, and sulfide-oxidizing Thiotrichales, matches the most favorable microbial metabolisms at methane seeps in terms of substrate supply and distinguishes the seep microbiome from other seafloor microbiomes. The key functional taxa varied in relative sequence abundance between different seeps due to the environmental factors, sediment depth and seafloor temperature. The degree of endemism of the methane seep microbiome suggests a high local diversification in these heterogeneous but long-lived ecosystems. Our results indicate that the seep microbiome is structured according to metacommunity processes and that few cosmopolitan microbial taxa mediate the bulk of methane oxidation, with global relevance to methane emission in the ocean. PMID:25775520

  20. Anaerobic oxidation of methane in the Concepción Methane Seep Area, Chilean continental margin

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Linke, P.; Scholz, F.; Schmidt, M.; Liebetrau, V.; Treude, T.

    2012-04-01

    Within subduction zones of active continental margins, large amounts of methane can be mobilized by dewatering processes and transported to the seafloor along migration pathways. A recently discovered seep area located off Concepción (Chile) at water depth between 600 to 1100 mbsl is characterized by active methane vent sites as well as massive carbonates boulders and plates which probably are related to methane seepage in the past. During the SO210 research expedition "Chiflux" (Sept-Oct 2010), sediment from the Concepción Methane Seep Area (CSMA) at the fore arc of the Chilean margin was sampled to study microbial activity related to methane seepage. We sampled surface sediments (0-30cm) from sulfur bacteria mats, as well as clam, pogonophoran, and tubeworm fields with push cores and a TV-guided multicorer system. Anaerobic oxidation of methane (AOM) and sulfate reduction rates were determined using ex-situ radioisotope tracer techniques. Additionally, porewater chemistry of retrieved cores as well as isotopic composition and age record of surrounding authigenic carbonates were analyzed. The shallowest sulfate-methane-transition zone (SMTZ) was identified at 4 cm sediment depth hinting to locally strong fluid fluxes. However, a lack of Cl- anomalies in porewater profiles indicates a shallow source of these fluids, which is supported by the biogenic origin of the methane (δ13C -70‰ PDB). Sulfide and alkalinity was relatively high (up to 20 mM and 40 mEq, respectively). Rates of AOM and sulfate reduction within this area reached magnitudes typical for seeps with variation between different habitat types, indicating a diverse methane supply, which is affecting the depths of the SMTZ. Rates were highest at sulfur a bacteria mats (20 mmol m-2 d-1) followed by a large field of dead clams, a pogonophoran field, a black sediment spot, and a carbonate rich clam field. Lowest rates (0.2 mmol m-2 d-1) were measured in close vicinity to these hot spots. Abundant massive

  1. Actinobacterial Diversity in the Sediments of Five Cold Springs on the Qinghai-Tibet Plateau

    PubMed Central

    Yang, Jian; Li, Xiaoyan; Huang, Liuqin; Jiang, Hongchen

    2015-01-01

    The actinobacterial diversity was investigated in the sediments of five cold springs in Wuli region on the Qinghai-Tibet Plateau using 16S rRNA gene phylogenetic analysis. The actinobacterial communities of the studied cold springs were diverse and the obtained actinobacterial operational taxonomic units were classified into 12 actinobacterial orders (e.g., Acidimicrobiales, Corynebacteriales, Gaiellales, Geodermatophilales, Jiangellales, Kineosporiales, Micromonosporales, Micrococcales, Nakamurellales, Propionibacteriales, Pseudonocardiales, Streptomycetales) and unclassified Actinobacteria. The actinobacterial composition varied among the investigated cold springs and were significantly correlated (r = 0.748, P = 0.021) to environmental variables. The actinobacterial communities in the cold springs were more diverse than other cold habitats on the Tibetan Plateau, and their compositions showed unique geographical distribution characteristics. Statistical analyses showed that biogeographical isolation and unique environmental conditions might be major factors influencing actinobacterial distribution among the investigated cold springs. PMID:26648925

  2. Metagenomics unveils the attributes of the alginolytic guilds of sediments from four distant cold coastal environments: Alginolytic guilds from cold sediments

    SciTech Connect

    Matos, Marina N.; Lozada, Mariana; Anselmino, Luciano E.; Musumeci, Matías A.; Henrissat, Bernard; Jansson, Janet K.; Mac Cormack, Walter P.; Carroll, JoLynn; Sjöling, Sara; Lundgren, Leif; Dionisi, Hebe M.

    2016-07-18

    Alginates are abundant polysaccharides in brown algae that constitute an important energy source for marine heterotrophic bacteria. Despite the key role of alginate assimilation processes in the marine carbon cycle, little information is available on the bacterial populations involved in these processes. The goal of this work was to gain insight into the structure and functional traits of the alginolytic communities from sediments of cold coastal environments. Sediment metagenomes from high-latitude regions of both Hemispheres were interrogated for alginate lyase gene homolog sequences and their genomic context. Sediments contained highly abundant and diverse bacterial assemblages with alginolytic potential, including members of Bacteroidetes and Proteobacteria, as well as several poorly characterized taxa. Temperature and salinity were correlated to the variation in community structure. The microbial communities in Arctic and Antarctic sediments exhibited the most similar alginolytic profiles, whereas brackish sediments had a higher proportion of novel members. Examination of the gene context of the alginate lyase homologs revealed distinct patterns according to the phylogenetic origin of the scaffolds, with evidence of evolutionary relationships among lineages. This information is relevant for understanding carbon fluxes in cold coastal environments and provides valuable information for the development of biotechnological applications from brown algae biomass.

  3. A paradox resolved: sulfide acquisition by roots of seep tubeworms sustains net chemoautotrophy.

    PubMed

    Freytag, J K; Girguis, P R; Bergquist, D C; Andras, J P; Childress, J J; Fisher, C R

    2001-11-06

    Vestimentiferan tubeworms, symbiotic with sulfur-oxidizing chemoautotrophic bacteria, dominate many cold-seep sites in the Gulf of Mexico. The most abundant vestimentiferan species at these sites, Lamellibrachia cf. luymesi, grows quite slowly to lengths exceeding 2 meters and lives in excess of 170-250 years. L. cf. luymesi can grow a posterior extension of its tube and tissue, termed a "root," down into sulfidic sediments below its point of original attachment. This extension can be longer than the anterior portion of the animal. Here we show, using methods optimized for detection of hydrogen sulfide down to 0.1 microM in seawater, that hydrogen sulfide was never detected around the plumes of large cold-seep vestimentiferans and rarely detectable only around the bases of mature aggregations. Respiration experiments, which exposed the root portions of L. cf. luymesi to sulfide concentrations between 51-561 microM, demonstrate that L. cf. luymesi use their roots as a respiratory surface to acquire sulfide at an average rate of 4.1 micromol x g(-1) x h(-1). Net dissolved inorganic carbon uptake across the plume of the tubeworms was shown to occur in response to exposure of the posterior (root) portion of the worms to sulfide, demonstrating that sulfide acquisition by roots of the seep vestimentiferan L. cf. luymesi can be sufficient to fuel net autotrophic total dissolved inorganic carbon uptake.

  4. Deep sequencing of Myxilla (Ectyomyxilla) methanophila, an epibiotic sponge on cold-seep tubeworms, reveals methylotrophic, thiotrophic, and putative hydrocarbon-degrading microbial associations.

    PubMed

    Arellano, Shawn M; Lee, On On; Lafi, Feras F; Yang, Jiangke; Wang, Yong; Young, Craig M; Qian, Pei-Yuan

    2013-02-01

    The encrusting sponge Myxilla (Ectyomyxilla) methanophila (Poecilosclerida: Myxillidae) is an epibiont on vestimentiferan tubeworms at hydrocarbon seeps on the upper Louisiana slope of the Gulf of Mexico. It has long been suggested that this sponge harbors methylotrophic bacteria due to its low δ(13)C value and high methanol dehydrogenase activity, yet the full community of microbial associations in M. methanophila remained uncharacterized. In this study, we sequenced 16S rRNA genes representing the microbial community in M. methanophila collected from two hydrocarbon-seep sites (GC234 and Bush Hill) using both Sanger sequencing and next-generation 454 pyrosequencing technologies. Additionally, we compared the microbial community in M. methanophila to that of the biofilm collected from the associated tubeworm. Our results revealed that the microbial diversity in the sponges from both sites was low but the community structure was largely similar, showing a high proportion of methylotrophic bacteria of the genus Methylohalomonas and polycyclic aromatic hydrocarbon (PAH)-degrading bacteria of the genera Cycloclasticus and Neptunomonas. Furthermore, the sponge microbial clone library revealed the dominance of thioautotrophic gammaproteobacterial symbionts in M. methanophila. In contrast, the biofilm communities on the tubeworms were more diverse and dominated by the chemoorganotrophic Moritella at GC234 and methylotrophic Methylomonas and Methylohalomonas at Bush Hill. Overall, our study provides evidence to support previous suggestion that M. methanophila harbors methylotrophic symbionts and also reveals the association of PAH-degrading and thioautotrophic microbes in the sponge.

  5. Methane Seep Carbonates Host Distinct, Diverse, and Dynamic Microbial Assemblages.

    PubMed

    Case, David H; Pasulka, Alexis L; Marlow, Jeffrey J; Grupe, Benjamin M; Levin, Lisa A; Orphan, Victoria J

    2015-12-22

    Marine 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., Chloroflexi operational 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. Since their discovery in 1984, the global distribution and importance of marine methane seeps have become increasingly clear. Much of our understanding of

  6. Eukaryotic diversity in late Pleistocene marine sediments around a shallow methane hydrate deposit in the Japan Sea.

    PubMed

    Kouduka, M; Tanabe, A S; Yamamoto, S; Yanagawa, K; Nakamura, Y; Akiba, F; Tomaru, H; Toju, H; Suzuki, Y

    2017-09-01

    Marine sediments contain eukaryotic DNA deposited from overlying water columns. However, a large proportion of deposited eukaryotic DNA is aerobically biodegraded in shallow marine sediments. Cold seep sediments are often anaerobic near the sediment-water interface, so eukaryotic DNA in such sediments is expected to be preserved. We investigated deeply buried marine sediments in the Japan Sea, where a methane hydrate deposit is associated with cold seeps. Quantitative PCR analysis revealed the reproducible recovery of eukaryotic DNA in marine sediments at depths up to 31.0 m in the vicinity of the methane hydrate deposit. In contrast, the reproducible recovery of eukaryotic DNA was limited to a shallow depth (8.3 m) in marine sediments not adjacent to the methane hydrate deposit in the same area. Pyrosequencing of an 18S rRNA gene variable region generated 1,276-3,307 reads per sample, which was sufficient to cover the biodiversity based on rarefaction curves. Phylogenetic analysis revealed that most of the eukaryotic DNA originated from radiolarian genera of the class Chaunacanthida, which have SrSO4 skeletons, the sea grass genus Zostera, and the seaweed genus Sargassum. Eukaryotic DNA originating from other planktonic fauna and land plants was also detected. Diatom sequences closely related to Thalassiosira spp., indicative of cold climates, were obtained from sediments deposited during the last glacial period (MIS-2). Plant sequences of the genera Alnus, Micromonas, and Ulmus were found in sediments deposited during the warm interstadial period (MIS-3). These results suggest the long-term persistence of eukaryotic DNA from terrestrial and aquatic sources in marine sediments associated with cold seeps, and that the genetic information from eukaryotic DNA from deeply buried marine sediments associated with cold seeps can be used to reconstruct environments and ecosystems from the past. © 2017 John Wiley & Sons Ltd.

  7. Tracking California seafloor seeps with bathymetry, backscatter and ROVs

    NASA Astrophysics Data System (ADS)

    Orange, Daniel L.; Yun, Janet; Maher, Norman; Barry, James; Greene, Gary

    2002-11-01

    The California (USA) margin includes two different tectonic regimes: subduction north of the Mendocino Triple Junction and translation south. Both margins include seeps, and their distribution can be inferred using seafloor bathymetry and backscatter as well as subsurface seismic data. Anomalous bathymetric and backscatter features related to fluid expulsion include headless submarine canyons, fault zones, anticlines, pockmarks, and mud volcanoes. Anomalous backscatter may be caused by authigenic carbonate (related to the bacterial oxidation of methane) or cold seep clams—both have an impedance and roughness that may be higher than the surrounding seafloor. Remote-operated vehicle (ROV) dives to such suspect seep sites document the presence of extensive authigenic carbonate, areally restricted cold seep communities, carpets of chemoautotrophic bacteria, and bubbling gas. Our operations in the Monterey Bay, on the translational California margin, and the Eel River basin, on the convergent margin, indicate that bathymetric and backscatter maps of the seafloor, if sufficiently high resolution, can be used to map seep sites, and that the distribution of such seeps can be used to constrain subsurface conduits of fluid flow. ROVs, due to their combination of visualization, propulsion, manipulation, sonar, and navigation, provide an excellent platform for ground-truthing, mapping, and sampling seafloor seeps.

  8. Cenozoic Methane-Seep Faunas of the Caribbean Region.

    PubMed

    Kiel, Steffen; Hansen, Bent T

    2015-01-01

    We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted 'Bath Cliffs fauna' containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema). In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman's Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical 'Cenozoic' lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large lucinids because they

  9. Cenozoic Methane-Seep Faunas of the Caribbean Region

    PubMed Central

    Kiel, Steffen; Hansen, Bent T.

    2015-01-01

    We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted ‘Joes River fauna’ consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted ‘Bath Cliffs fauna’ containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema). In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman’s Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical ‘Cenozoic’ lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large lucinids

  10. Methane seep events of the southern Joetsu Knoll since middle Pleistocene based on benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Oi, T.; Akiba, F.; Matsumoto, R.; Kakuwa, Y.

    2016-12-01

    Gas hydrates were collected at several sites off Joetsu which presented anomalous seismic structures. "Gas chimneys", major host structures for shallow gas hydrates, were recognized ROV off Joetsu in eastern margin of the Japan Sea, as were a number of active methane seeps. The assemblage components and carbon isotope of benthic foraminifera, which are ubiquitous in global marine settings, can indicate methane seep environments (Akimoto et al., 1994; Bhaumik and Gupta, 2007). Preliminary work by Oi et al. (2015) documented the obvious occurrences of methane related foraminifera, Rutherfordoides sp., in three core sediments recovered from Umitaka Spur, west Oki Trough and north Mogami Trough in the eastern margin of the Japan Sea, and found them to comprise the early part of the MIS 2, calculated to 28-25ka. These records suggest that active methane seep events might occur at the same time during early MIS 2, but were confined within the last 100ka. In this study, we analyzed benthic foraminiferal fossils from drilling core J04RB (core length 122 m; one of the gas hydrate bearing sites at a southern part of the Joetsu Knoll) in order to document methane seep events during the last 500ka. Firstly, we estimated sedimentation ages from diatom biostratigraphy and identification of Aso-1 tephra. Based on diatom components, we recognized a boundary between NPD (Neogene North Pacific diatom Zonations) 12 and NPD11, estimated at 300 ka (MIS8/9; Yanagisawa and Akiba, 1998). The bottom age was estimated to almost 530-560 ka (around MIS14) especially from the alternation with warm and cold diatom zones (Akiba et al., 2014). Secondary, we could suppose the paleoenvironments from benthic foraminifera as below. 1. The rare benthic foraminifera during the cold stages (MIS8, MIS10, and MIS12) indicate anoxic bottom conditions characteristic of falling sea level, just as with MIS 2. 2. We recognized the continuous distributions of tiny methane related specimens of Rutherfordoides sp

  11. Trace Elemental Geochemistry of Pacific Margin Seep and Non-seep Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Burkett, A. M.; Rathburn, A. E.; De Deckker, P.; Perez, M. E.

    2015-12-01

    As part of a continued effort to evaluate factors that influence carbonate biogeochemistry of living foraminifera, stable isotopic and trace elemental analyses of epibenthic and infaunal species of benthic foraminifera collected from the Pacific margin revealed clues for assessment of the presence, history and origin of cold and hydrothermal methane seepage sites. Hydrothermal seeps have only recently been discovered, prioritizing their recognition and assessments of the origins/sources of these anomalously warm environments. Trace elements were analyzed with a laser ablation ICP-MS at the Australian National University, avoiding contamination and allowing measurements of recently generated chambers. Living Cibicidoides wuellerstorfi and Uvigerina peregrina collected from active methane seeps on the east Pacific margin (Costa Rica, Alaska and Hydrate Ridge) have a wider range in both stable isotopic signals and some trace elemental values (e.g., Mg/Ca) compared to nearby inactive areas. Comparisons of additional trace elemental values (e.g., Li/Ca, Cd/Ca, B/Ca, and Ba/Ca) from living Cibicidoides wuellerstorfi and Uvigerina peregrina from these unique seafloor environments provide additional information in the geochemical influences of cold and hydrothermal seepage on foraminiferal calcite geochemistry. Seep environments are often the result of complex tectonic processes, have implications in past rapid climatic shifts and in future climate change predictions and models, and can influence modern ecosystems and biogeochemical cycles in ways which are not fully understood. Benthic foraminiferal geochemistry provides a potential means to identify seep fluid origins, elucidate seep fluid records and recognize hydrothermal seeps and their spatial and temporal history.

  12. NASA and SEEP

    NASA Astrophysics Data System (ADS)

    Lynch, John T.

    In the recent news note by R. E. Hartle entitled ‘Detecting Electron Precipitation’ (Eos, March 22, 1983, p. 114), it is staled that NASA performed an experiment ‘similar’ to the Navy's Stimulated Emission of Energetic Particles (SEEP) satellite program using sounding rocket X ray detectors. The NASA effort was actually a cooperative part of the SEEP program that was, with the exception of the two small NASA rockets, sponsored entirely by the Office of Naval Research. The SEEP program originated at Lockheed Palo Alto Research Laboratory and Stanford University and was well along before Dr. Goldberg at Goddard Space Flight Center and his coinvestigators at Cornell and the University of Denver were invited to participate.

  13. Thermally Released Arsenic in Porewater from Sediments in the Cold Lake Area of Alberta, Canada.

    PubMed

    Javed, Muhammad Babar; Siddique, Tariq

    2016-03-01

    Elevated arsenic (As) in aquifers in close proximity to in situ oil sands extraction in the Cold Lake area, Alberta, Canada is attributed to high temperature steam (~200 °C) injected into oil sands deposits to liquefy bitumen. Heat propagated from hot injection wells alters physicochemical properties of the surrounding sediments and associated porewater. Seven sediments from four different cores drilled up to ~300 m depth collected from different locations in the area were used to study the thermal effect (~200 °C) on As distribution in the sediments and its release into porewater. Sediments were moistened with synthetic aquifer or deionized water according to the moisture regimes present in aquitard, aquifer and fractured zones. Heat application greatly released As in the porewater (500-5200 and 1200-6600 μg L(-1)) from aquifer and fractured sediments, respectively. Mass balance of As chemical fractionation showed that ~89-100% of As in porewater was released from exchangeable and specifically adsorbed As in the sediments. Heat application also altered As distribution in the sediments releasing As from exchange surfaces and amorphous Fe oxides to soluble As fraction. The results provide great insight into As release mechanisms warranting development of strategies to mitigate groundwater As contamination during industrial operation.

  14. Microbial characterization of a subzero, hypersaline methane seep in the Canadian High Arctic.

    PubMed

    Niederberger, Thomas D; Perreault, Nancy N; Tille, Stephanie; Lollar, Barbara Sherwood; Lacrampe-Couloume, Georges; Andersen, Dale; Greer, Charles W; Pollard, Wayne; Whyte, Lyle G

    2010-10-01

    We report the first microbiological characterization of a terrestrial methane seep in a cryo-environment in the form of an Arctic hypersaline (∼24% salinity), subzero (-5 °C), perennial spring, arising through thick permafrost in an area with an average annual air temperature of -15 °C. Bacterial and archaeal 16S rRNA gene clone libraries indicated a relatively low diversity of phylotypes within the spring sediment (Shannon index values of 1.65 and 1.39, respectively). Bacterial phylotypes were related to microorganisms such as Loktanella, Gillisia, Halomonas and Marinobacter spp. previously recovered from cold, saline habitats. A proportion of the bacterial phylotypes were cultured, including Marinobacter and Halomonas, with all isolates capable of growth at the in situ temperature (-5 °C). Archaeal phylotypes were related to signatures from hypersaline deep-sea methane-seep sediments and were dominated by the anaerobic methane group 1a (ANME-1a) clade of anaerobic methane oxidizing archaea. CARD-FISH analyses indicated that cells within the spring sediment consisted of ∼84.0% bacterial and 3.8% archaeal cells with ANME-1 cells accounting for most of the archaeal cells. The major gas discharging from the spring was methane (∼50%) with the low CH(4)/C(2+) ratio and hydrogen and carbon isotope signatures consistent with a thermogenic origin of the methane. Overall, this hypersaline, subzero environment supports a viable microbial community capable of activity at in situ temperature and where methane may behave as an energy and carbon source for sustaining anaerobic oxidation of methane-based microbial metabolism. This site also provides a model of how a methane seep can form in a cryo-environment as well as a mechanism for the hypothesized Martian methane plumes.

  15. Metagenomics unveils the attributes of the alginolytic guilds of sediments from four distant cold coastal environments.

    PubMed

    Matos, Marina N; Lozada, Mariana; Anselmino, Luciano E; Musumeci, Matías A; Henrissat, Bernard; Jansson, Janet K; Mac Cormack, Walter P; Carroll, JoLynn; Sjöling, Sara; Lundgren, Leif; Dionisi, Hebe M

    2016-12-01

    Alginates are abundant polysaccharides in brown algae that constitute an important energy source for marine heterotrophic bacteria. Despite the key role of alginate degradation processes in the marine carbon cycle, little information is available on the bacterial populations involved in these processes. The aim of this work was to gain a better understanding of alginate utilization capabilities in cold coastal environments. Sediment metagenomes from four high-latitude regions of both Hemispheres were interrogated for alginate lyase gene homologue sequences and their genomic context. Sediments contained highly abundant and diverse bacterial assemblages with alginolytic potential, including members of Bacteroidetes and Proteobacteria, as well as several poorly characterized taxa. The microbial communities in Arctic and Antarctic sediments exhibited the most similar alginolytic profiles, whereas brackish sediments showed distinct structures with a higher proportion of novel genes. Examination of the gene neighbourhood of the alginate lyase homologues revealed distinct patterns depending on the potential lineage of the scaffolds, with evidence of evolutionary relationships among alginolytic gene clusters from Bacteroidetes and Proteobacteria. This information is relevant for understanding carbon fluxes in cold coastal environments and provides valuable information for the development of biotechnological applications from brown algae biomass.

  16. SHEEP CREEK SEEP CHARACTERIZATION

    EPA Science Inventory

    The materials presented represent an assessment of site conditions related to the LaCrone property seep, located in the NW 1/4 of Section 34, Township 7E, Range 2N, near Harden City, OK. The primary objective of the study was to identify possible source(s) for the saline water, ...

  17. SHEEP CREEK SEEP CHARACTERIZATION

    EPA Science Inventory

    The materials presented represent an assessment of site conditions related to the LaCrone property seep, located in the NW 1/4 of Section 34, Township 7E, Range 2N, near Harden City, OK. The primary objective of the study was to identify possible source(s) for the saline water, ...

  18. Evolution and biogeography of deep-sea vent and seep invertebrates.

    PubMed

    Van Dover, C L; German, C R; Speer, K G; Parson, L M; Vrijenhoek, R C

    2002-02-15

    Deep-sea hydrothermal vents and cold seeps are submarine springs where nutrient-rich fluids emanate from the sea floor. Vent and seep ecosystems occur in a variety of geological settings throughout the global ocean and support food webs based on chemoautotrophic primary production. Most vent and seep invertebrates arrive at suitable habitats as larvae dispersed by deep-ocean currents. The recent evolution of many vent and seep invertebrate species (<100 million years ago) suggests that Cenozoic tectonic history and oceanic circulation patterns have been important in defining contemporary biogeographic patterns.

  19. Isolation and Physiological Characterization of Psychrophilic Denitrifying Bacteria from Permanently Cold Arctic Fjord Sediments (Svalbard, Norway)

    NASA Technical Reports Server (NTRS)

    Canion, Andy; Prakash, Om; Green, Stefan J.; Jahnke, Linda; Kuypers, Marcel M. M.; Kostka, Joel E.

    2013-01-01

    A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(sup 3)-10(sup 6) cells of psychrophilic nitrate-respiring bacteria g(sup -1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40 degC demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15 degC, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

  20. Isolation and physiological characterization of psychrophilic denitrifying bacteria from permanently cold Arctic fjord sediments (Svalbard, Norway).

    PubMed

    Canion, Andy; Prakash, Om; Green, Stefan J; Jahnke, Linda; Kuypers, Marcel M M; Kostka, Joel E

    2013-05-01

    A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(3) -10(6) cells of psychrophilic nitrate-respiring bacteria g(-1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40°C demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15°C, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

  1. Comparing Reactive Surface Area of Sediments in Hot and Cold Arid Climates

    NASA Astrophysics Data System (ADS)

    Funderburg, R.; Elwood Madden, M.; Joo, Y. J.; Marra, K. R.; Soreghan, G. S.; Hall, B. L.

    2014-12-01

    The reactive surface area of primary silicate phases in sediment is an important determinant in weathering rates and fluxes in the critical zone. Weathering rates in warm climates are presumed to be faster than rates in cold climates, but glacial stream systems have chemical fluxes similar to temperate climates due to the production of highly reactive fresh mineral surfaces. To assess climate as a controller on weathering rates by comparing reactive surface area in cold arid and hot arid systems, samples were collected at the base of Denton Glacier, Wright Valley, Antarctica, and in the Anza Borrego Desert, California. Sediments were wet sieved and treated to remove carbonates and organics. Mud and very fine fractions were freeze dried. Surface areas of each size fraction were determined using the BET method. Sediment reactivity was measured through batch dissolution experiments in water buffered to pH 8.4. Samples were removed and filtered at predetermined time intervals, then refrigerated prior to ICP-OES analysis. Antarctic glacial sediment released an order of magnitude or more cations to solution compared to alluvial sediments from the Anza Borrego Desert. The Anza Borrego sand fraction was more reactive than the mud for Ca, P, Mn, and Si, while the Antarctic mud was more reactive than the sand for all cations. The high reactivity of the glacial mud can be attributed to the high reactive surface area (10.42 m2/g) created by physical crushing. In addition, the cation exchange capacity of the mud fraction was reached more quickly in the Antarctica samples, while Anza Borrego muds produced more complicated weathering fluxes, likely due to their higher clay mineral component. These results emphasize a strong climate control and the importance of physical weathering mechanisms on the chemical weathering fluxes over geologic time scales.

  2. Methane emission and consumption at a North Sea gas seep (Tommeliten area)

    NASA Astrophysics Data System (ADS)

    Niemann, H.; Elvert, M.; Hovland, M.; Orcutt, B.; Judd, A.; Suck, I.; Gutt, J.; Joye, S.; Damm, E.; Finster, K.; Boetius, A.

    2005-11-01

    The North Sea hosts large coal, oil and gas reservoirs of commercial value. Natural leakage pathways of subsurface gas to the hydrosphere have been recognized during geological surveys (Hovland and Judd, 1988). The Tommeliten seepage area is part of the Greater Ekofisk area, which is situated above the Tommeliten Delta salt diapir in the central North Sea. In this study, we report of an active seep site (56°29.90'N, 2°59.80'E) located in the Tommeliten area, Norwegian Block 1/9, at 75 m water depth. Here, cracks in a buried marl horizon allow methane to migrate into overlying clay-silt and sandy sediments. Hydroacoustic sediment echosounding showed several venting spots coinciding with the apex of marl domes where methane is released into the water column and potentially to the atmosphere during deep mixing situations. In the vicinity of the gas seeps, sea floor observations showed small mats of giant sulphide-oxidizing bacteria above patches of black sediments and carbonate crusts, which are exposed 10 to 50 cm above seafloor forming small reefs. These Methane-Derived Authigenic Carbonates (MDACs) contain 13C-depleted, archaeal lipids indicating previous gas seepage and AOM activity. High amounts of sn2-hydroxyarchaeol relative to archaeol and low abundances of biphytanes in the crusts give evidence that ANaerobic MEthane-oxidising archaea (ANME) of the phylogenetic cluster ANME-2 were the potential mediators of Anaerobic Oxidation of Methane (AOM) at the time of carbonate formation. Small pieces of MDACs were also found subsurface at about 1.7 m sediment depth, associated with the Sulphate-Methane Transition Zone (SMTZ). The SMTZ of Tommeliten is characterized by elevated AOM and Sulphate Reduction (SR) rates, increased concentrations of 13C-depleted tetraether derived biphytanes, and specific bacterial Fatty Acids (FA). Further biomarker and 16S rDNA based analyses give evidence that AOM at the Tommeliten SMTZ is mediated by archaea belonging to the ANME-1b

  3. A kinetic model for the methane hydrate precipitated from venting gas at cold seep sites at Hydrate Ridge, Cascadia margin, Oregon

    NASA Astrophysics Data System (ADS)

    Cao, Yuncheng; Chen, Duofu; Cathles, Lawrence M.

    2013-09-01

    develop a kinetic model for hydrate crystallization from methane gas venting through shallow sediments at Hydrate Ridge on the Cascadia margin of Oregon that predicts how pore water chlorinity, temperature, and crystallized hydrate evolve after the onset of steady venting. Predictions are compared to observations at Ocean Drilling Program Site 1249. In the preferred model, calculated gas hydrate saturation and chloride concentrations reach those observed at depths less than 20 m below seafloor (bsf) under the southern summit of Hydrate Ridge in ~650 years, and the vertical water flux must be less than 50 kg/m2/yr. Hydrate accumulates more slowly between 20 m bsf and the base of the hydrate stability zone where there is no free gas, accumulating to observed levels of a few volume percent of hydrate in 105 to 106 years, depending on the water flux that is assumed through this zone. This dichotomy means that the presently observed gas venting must have been diverted to this area ~650 years ago, or be episodic and infrequent. If the gas venting for the last 650 years has been as observed today, the latent heat of hydrate precipitation in the upper 20 m of sediments would have caused the temperature to increase ~0.8°C at ~20 m bsf and ~0.2°C at ~100 m bsf. This would have caused a ~5 m rise in the elevation of the base of hydrate stability zone, and decreased the rate of hydrate crystallization from 1.5 kg CH4/m2/yr 650 years ago to 0.7 kg CH4/m2/yr today.

  4. Abyssal seep site cementation

    SciTech Connect

    Neumann, A.C.; Paull, C.K.; Commeau, R.; Commeau, J.

    1988-01-01

    The deepest submarine cements known so far occur along the 3,300-m deep base of the Florida escarpment and are associated with methane-bearing brine seeps, which emanate there. These deep Holocene carbonates, which occur as surficial and buried crusts, burrow fillings, and friable horizons, were sampled via ALVIN. The carbonates form irregular halos extending up to 20 m from seeps colonized by chemosynthetic fauna. Mussels, gastropods, and clams, the carbonate components of the community, produce a shell hash that is locally cemented by coarsely crystalline low-Mg calcite. Halos of palisade calcite are reminiscent of ancient examples of marine cements. Also present are carbonate hemipelagics cemented by micrite into crusts and burrow fillings. The degree of cementation varies from pervasive to light. Slabs of cemented crust up to 30 cm thick contrast with typical shallow crusts and exhibit irregular tops and smooth bottoms indicating different chemical gradients and pathways.

  5. Does the "sleeping Dragon" Really Sleep?: the Case for Continuous Long-Term Monitoring at a Gulf of Mexico Cold Seep Site

    NASA Astrophysics Data System (ADS)

    Wilson, R. M.; Lapham, L.; Farr, N.; Lutken, C.; MacDonald, I. R.; Macelloni, L.; Riedel, M.; Sleeper, K.; Chanton, J.

    2011-12-01

    Continuous porewater monitoring indicates that the methane flux away from exposed hydrate mounds can vary considerably over time. Recently, we retrieved a Pore Fluid Array instrument pack from a hydrate outcrop adjacent to a NEPTUNE Canada observatory node. The sampler was designed to continuously collect and store sediment pore fluids over the course of 9 months. On analysis, we observed a 35mM variation in methane concentrations corresponding with an abrupt shift in current direction at the site. Video and resistivity data have led to previous speculation that hydrate growth and dissolution/dissociation may be seasonally variable. Cumulatively, these findings suggest that the persistence of hydrate outcrops may be extremely dynamic, driven by fluctuations in physical conditions on short time scales. Short-term monitoring in the Gulf of Mexico within Mississippi Canyon lease block 118 (MC118), a known hydrate-bearing site, indicates that physical conditions even at these depths (~540-890m) may be highly variable. Pressure can vary within hours, and recorded temperature changes of ~1.5°C have been associated with passing storms. Moreover, increased particle abundance was observed at the site in 2007 suggesting that organic matter flux to the sediments may vary on the scale of months to years. These inputs have the potential to alter the chemical environment surrounding the hydrate, thereby affecting dissolution rates. Continuous, long-term observations of physical conditions at MC118 could provide information about the potential for natural perturbations to impact hydrate dynamics on the scale of weeks or even days necessary for assessing the long-term persistence of hydrate outcrops. Sleeping Dragon is a massive hydrate outcrop at MC118 that has been monitored since 2006. Three years ago, researchers returning to the site found it visibly diminished relative to previous observations. This apparent shift toward net dissolution of the mound may have been

  6. Identity, Abundance, and Reactivation Kinetics of Thermophilic Fermentative Endospores in Cold Marine Sediment and Seawater

    PubMed Central

    Volpi, Marta; Lomstein, Bente Aa.; Sichert, Andreas; Røy, Hans; Jørgensen, Bo B.; Kjeldsen, Kasper U.

    2017-01-01

    Cold marine sediments harbor endospores of fermentative and sulfate-reducing, thermophilic bacteria. These dormant populations of endospores are believed to accumulate in the seabed via passive dispersal by ocean currents followed by sedimentation from the water column. However, the magnitude of this process is poorly understood because the endospores present in seawater were so far not identified, and only the abundance of thermophilic sulfate-reducing endospores in the seabed has been quantified. We investigated the distribution of thermophilic fermentative endospores (TFEs) in water column and sediment of Aarhus Bay, Denmark, to test the role of suspended dispersal and determine the rate of endospore deposition and the endospore abundance in the sediment. We furthermore aimed to determine the time course of reactivation of the germinating TFEs. TFEs were induced to germinate and grow by incubating pasteurized sediment and water samples anaerobically at 50°C. We observed a sudden release of the endospore component dipicolinic acid immediately upon incubation suggesting fast endospore reactivation in response to heating. Volatile fatty acids (VFAs) and H2 began to accumulate exponentially after 3.5 h of incubation showing that reactivation was followed by a short phase of outgrowth before germinated cells began to divide. Thermophilic fermenters were mainly present in the sediment as endospores because the rate of VFA accumulation was identical in pasteurized and non-pasteurized samples. Germinating TFEs were identified taxonomically by reverse transcription, PCR amplification and sequencing of 16S rRNA. The water column and sediment shared the same phylotypes, thereby confirming the potential for seawater dispersal. The abundance of TFEs was estimated by most probable number enumeration, rates of VFA production, and released amounts of dipicolinic acid during germination. The surface sediment contained ∼105–106 inducible TFEs cm-3. TFEs thus outnumber

  7. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments

    PubMed Central

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R.; Jørgensen, Bo B.; Kjeldsen, Kasper U.

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  8. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments.

    PubMed

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R; Jørgensen, Bo B; Kjeldsen, Kasper U

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  9. Identity, Abundance, and Reactivation Kinetics of Thermophilic Fermentative Endospores in Cold Marine Sediment and Seawater.

    PubMed

    Volpi, Marta; Lomstein, Bente Aa; Sichert, Andreas; Røy, Hans; Jørgensen, Bo B; Kjeldsen, Kasper U

    2017-01-01

    Cold marine sediments harbor endospores of fermentative and sulfate-reducing, thermophilic bacteria. These dormant populations of endospores are believed to accumulate in the seabed via passive dispersal by ocean currents followed by sedimentation from the water column. However, the magnitude of this process is poorly understood because the endospores present in seawater were so far not identified, and only the abundance of thermophilic sulfate-reducing endospores in the seabed has been quantified. We investigated the distribution of thermophilic fermentative endospores (TFEs) in water column and sediment of Aarhus Bay, Denmark, to test the role of suspended dispersal and determine the rate of endospore deposition and the endospore abundance in the sediment. We furthermore aimed to determine the time course of reactivation of the germinating TFEs. TFEs were induced to germinate and grow by incubating pasteurized sediment and water samples anaerobically at 50°C. We observed a sudden release of the endospore component dipicolinic acid immediately upon incubation suggesting fast endospore reactivation in response to heating. Volatile fatty acids (VFAs) and H2 began to accumulate exponentially after 3.5 h of incubation showing that reactivation was followed by a short phase of outgrowth before germinated cells began to divide. Thermophilic fermenters were mainly present in the sediment as endospores because the rate of VFA accumulation was identical in pasteurized and non-pasteurized samples. Germinating TFEs were identified taxonomically by reverse transcription, PCR amplification and sequencing of 16S rRNA. The water column and sediment shared the same phylotypes, thereby confirming the potential for seawater dispersal. The abundance of TFEs was estimated by most probable number enumeration, rates of VFA production, and released amounts of dipicolinic acid during germination. The surface sediment contained ∼10(5)-10(6) inducible TFEs cm(-3). TFEs thus outnumber

  10. Low viral predation pressure in cold hypersaline Arctic sediments and limits on lytic replication.

    PubMed

    Colangelo-Lillis, Jesse; Wing, Boswell A; Whyte, Lyle G

    2016-04-01

    Viruses are ubiquitous drivers of microbial ecology and evolution and contribute to biogeochemical cycling. Attention to these attributes has been more substantial for marine viruses than viruses of other environments. Microscopy-based investigation of the viral communities from two cold, hypersaline Arctic springs was undertaken to explore the effects of these conditions on microbe-viral ecology. Sediments and water samples were collected along transects from each spring, from anoxic spring outlets through oxygenated downstream channels. Viral abundance, virus-microbe ratios and modelled virus-microbe contact rates were lower than comparable aqueous and sedimentary environments and most similar to deep subsurface sediments. No individual cell from either spring was visibly infected. Viruses in these springs appear to play a smaller role in controlling microbial populations through lytic activity than in marine water column or surface sedimentary environments. Relief from viral predation indicates the microbial communities are primarily controlled by nutrient limitation. The similarity of these springs to deep subsurface sediments suggests a biogeographic divide in viral replication strategy in marine sediments. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Sedimentation on the cold-water coral Lophelia pertusa: cleaning efficiency from natural sediments and drill cuttings.

    PubMed

    Larsson, Ann I; Purser, Autun

    2011-06-01

    Anthropogenic threats to cold-water coral reefs are trawling and hydrocarbon drilling, with both activities causing increased levels of suspended particles. The efficiency of Lophelia pertusa in rejecting local sediments and drill cuttings from the coral surface was evaluated and found not to differ between sediment types. Further results showed that the coral efficiently removed deposited material even after repeated exposures, indicating an efficient cleaning mechanism. In an experiment focusing on burial, fine-fraction drill cuttings were deposited on corals over time. Drill cutting covered coral area increased with repeated depositions, with accumulation mainly occurring on and adjacent to regions of the coral skeleton lacking tissue cover. Tissue was smothered and polyp mortality occurred where polyps became wholly covered by material. Burial of coral by drill cuttings to the current threshold level used in environmental risk assessment models by the offshore industry (6.3mm) may result in damage to L. pertusa colonies. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Methane Seep Carbonates Host Distinct, Diverse, and Dynamic Microbial Assemblages

    PubMed Central

    Pasulka, Alexis L.; Marlow, Jeffrey J.; Grupe, Benjamin M.; Levin, Lisa A.

    2015-01-01

    ABSTRACT Marine 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., Chloroflexi operational 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. PMID:26695630

  13. Rare earth elements of seep carbonates: Indication for redox variations and microbiological processes at modern seep sites

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Lin, Zhijia; Bian, Youyan; Chen, Duofu; Peckmann, Jörn; Bohrmann, Gerhard; Roberts, Harry H.

    2013-03-01

    At marine seeps, methane is microbially oxidized resulting in the precipitation of carbonates close to the seafloor. Methane oxidation leads to sulfate depletion in sediment pore water, which induces a change in redox conditions. Rare earth element (REE) patterns of authigenic carbonate phases collected from modern seeps of the Gulf of Mexico, the Black Sea, and the Congo Fan were analyzed. Different carbonate minerals including aragonite and calcite with different crystal habits have been selected for analysis. Total REE content (ΣREE) of seep carbonates varies widely, from 0.1 ppm to 42.5 ppm, but a common trend is that the ΣREE in microcrystalline phases is higher than that of the associated later phases including micospar, sparite and blocky cement, suggesting that ΣREE may be a function of diagenesis. The shale-normalized REE patterns of the seep carbonates often show different Ce anomalies even in samples from a specific site, suggesting that the formation conditions of seep carbonates are variable and complex. Overall, our results show that apart from anoxic, oxic conditions are at least temporarily common in seep environments.

  14. Insights into the activity, formation and origin of seep systems on the seafloor in the SW Barents Sea

    NASA Astrophysics Data System (ADS)

    Mangelsdorf, Kai; Nickel, Julia C.; di Primio, Rolando; Kallmeyer, Jens; Horsfield, Brian; Stoddart, Daniel; Brunstad, Harald

    2014-05-01

    The southwestern Loppa High region, being part of the Barents Sea located in the north of Norway, is a promising area for oil and gas exploration since hydrocarbon discoveries have been made in this area in recent time. Additionally, surface features for hydrocarbon seepage, so called "cold seeps" have been detected on the seafloor, comprising extensive pockmark fields, carbonate crusts bearing areas and fault related gas flares. Leaking hydrocarbons are of specific interest since they are potential indicators for hydrocarbon reservoirs in the subsurface and the emitting hydrocarbons such as the greenhouse gas methane can have significant impact on the evolution of global warming when reaching the atmosphere. In this study cold seep systems like huge pockmark areas and carbonate crust sites from the SW Loppa High region were examined in detail, in order to determine the activity, formation and spatial distribution of the different seepage structures as well as the origin and timing of the seeping hydrocarbon fluids. The sample material comprising sediment cores from pockmarks, reference sites and carbonate crust areas as well as carbonate crust samples have been analyzed applying a combined biogeochemical and microbiological approach. In the carbonate crust area diagnostic biomarkers for the anaerobic oxidation of methane (AOM) were detected in the sediments as well as in the corresponding carbonate crusts. Their depth profiles show a distinct interval of higher concentrations, which points towards a shallow AOM zone in the investigated core. The biomarkers were also characterized by very negative carbon isotope signatures, indicating the involvement of the source microorganisms in the process of AOM. These data and active gas bubbling during sampling indicate the presence of methane at the carbonate crust site. In contrast in the pockmark areas active release of gas from the sediment could not be observed, neither in the gas measurement nor in the biogeochemical

  15. Management of dryland saline seeps

    USDA-ARS?s Scientific Manuscript database

    Discussed is the identification, diagnosis, control, and reclamation of dryland saline seep problems as found in the North American Great Plains. Saline seeps develop because of geologic stratifications within the soil profile and insufficient use of precipitation by crops used in dryland farming s...

  16. Toward estimation of origin of methane at ancient seeps — Carbon isotopes of seep carbonates, lipid biomarkers, and adsorbed gas

    NASA Astrophysics Data System (ADS)

    Miyajima, Yusuke; Watanabe, Yumiko; Ijiri, Akira; Goto, Akiko; Jenkins, Robert; Hasegawa, Takashi; Sakai, Saburo; Matsumoto, Ryo

    2017-04-01

    Methane is generated mainly by microbial or thermal degradation of organic matter, and the origin of methane can be estimated based on its stable carbon isotopic signature. Seafloor seepages of methane-charged fluids have been a major source of methane to the ocean, and knowing the origin of methane at the methane seeps can provide valuable insights into the subsurface fluid circulation and biogeochemical processes. Methane seeps in the geological past are archived as authigenic methane-derived carbonate rocks, which precipitate via an alkalinity increase facilitated by microbially mediated anaerobic oxidation of methane. Here we attempted to estimate origins of methane at ancient seeps, based on several proxies preserved within the seep carbonates. We examined methane-seep carbonate rocks in the Japan Sea region, collected from lower Miocene to middle Pleistocene sediments at 11 sites on land, and also carbonate nodules collected from the seafloor off Joetsu, where thermogenic methane is seeping. Carbon isotopic compositions of the carbonates and lipid biomarkers of methane-oxidizing archaea within them were analyzed. In order to directly know original isotopic signatures of methane, we also attempted to extract adsorbed methane through acid dissolution of the powdered carbonates. Early-diagenetic carbonate phases show various δ13C values between -64.7 and -4.7‰ vs. VPDB, suggesting either biogenic or thermogenic, or both origins of methane. A lipid biomarker pentamethylicosane (PMI) extracted from the ancient carbonates has δ13C values mostly lower than -100‰ , whereas that from the modern methane-derived carbonate nodule has a higher value (-80‰ ). The δ13C values of the seeping methane (-36‰ ) and PMI in the modern Joetsu seep carbonate shows an offset of -44‰ . If this carbon isotope offset was similar at the ancient seeps, the δ13C values of PMI indicate that methane at ancient seeps in the Japan Sea region was biogenic in origin, with δ13C

  17. Methane seep carbonates yield clumped isotope signatures out of equilibrium with formation temperatures

    DOE PAGES

    Loyd, S. J.; Sample, J.; Tripati, R. E.; ...

    2016-07-22

    Here, methane cold seep systems typically exhibit extensive buildups of authigenic carbonate minerals, resulting from local increases in alkalinity driven by methane oxidation. Here, we demonstrate that modern seep authigenic carbonates exhibit anomalously low clumped isotope values (Δ47), as much as ~0.2‰ lower than expected values. In modern seeps, this range of disequilibrium translates into apparent temperatures that are always warmer than ambient temperatures, by up to 50 °C. We examine various mechanisms that may induce disequilibrium behaviour in modern seep carbonates, and suggest that the observed values result from several factors including kinetic isotopic effects during methane oxidation, mixingmore » of inorganic carbon pools, pH effects and rapid precipitation. Ancient seep carbonates studied here also exhibit potential disequilibrium signals. Ultimately, these findings indicate the predominance of disequilibrium clumped isotope behaviour in modern cold seep carbonates that must be considered when characterizing environmental conditions in both modern and ancient cold seep settings.« less

  18. Winter variability of aeolian sediment transport threshold on a cold-climate dune

    NASA Astrophysics Data System (ADS)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2012-12-01

    Changes in surface conditions on cold-climate aeolian dunes are pronounced; during winter dunes are wet, snow covered, and/or frozen for extended periods of time. It is unknown how the critical wind speed for sediment transport (“threshold”) varies and how threshold may influence sediment transport predictions. Although the impact of surface conditions on threshold has been examined in synthetic experiments (wind tunnels), complicated feedbacks between threshold, sand transport, and surface conditions that occur in natural environments suggest that a ground-based empirical approach may provide enhanced insight. In this study we investigate threshold variability for 73 days during fall-winter-spring surface conditions from 18 November 2008 to 30 May 2009 in the Bigstick Sand Hills of Saskatchewan, Canada. Simultaneous measurements of threshold and atmospheric variables (air temperature, relative humidity, solar radiation, wind speed and direction) were used to examine the extent to which surface erodibility was regulated by meteorology. Time-lapse images of the surface from a co-located camera were used for quality control and interpreting changes in the surface affecting threshold. Results reveal that threshold varied throughout the deployment (25-75% quartiles: 6.92-8.28 m s- 1; mean: 7.79 m s- 1). Threshold variability was especially evident at two scales: (i) event timescale and (ii) seasonal timescale. Event-scale variability peaked during mid-winter; in one event the threshold varied by 6 m s- 1 in 2 h with freezing and re-freezing of the surface and relatively constant atmospheric conditions. The causes of event-scale variability are complex though qualitatively related to changes of wind direction, antecedent meteorological conditions, and vertical variations of grain-scale bonding agents such as pore ice and moisture. Seasonal-scale changes manifested as an increase in threshold during fall, peaking in mid-winter, and decreasing in spring. Increased

  19. Interactions between sediment chemistry and frenulate pogonophores (Annelida) in the north-east Atlantic

    NASA Astrophysics Data System (ADS)

    Dando, P. R.; Southward, A. J.; Southward, E. C.; Lamont, P.; Harvey, R.

    2008-08-01

    The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit muddy sediments on the continental slope, although a few species occur near hydrothermal vents and cold seeps. We present data on the distribution and habitat characteristics of several species on the European continental shelf and slope from 48°N to 75°N and show how the animals interact with the chemistry of the sediments. The environments inhabited include: shallow (30 m), organic-rich, fjord sediments; slope sediments (1000-2200 m) and methane seeps at 330 m depth. All the species studied obtain nutrition from endosymbiotic bacteria. They take up reduced sulphur species, or in one case, methane, through the posterior parts of their tubes buried in the anoxic sediment. We conclude that most species undertake sulphide 'mining', a mechanism previously demonstrated in the bivalves Lucinoma borealis and Thyasira sarsi. These pogonophores participate in the sulphur cycle and effectively lower the sulphide content of the sediments. Our results show that the abundance of frenulate pogonophores increases with increasing sedimentation and with decreasing abundance of other benthos, particularly bioturbating organisms. The maximum sustainable carrying capacity of non-seep sediments for frenulate pogonophores is limited by the rate of sulphate reduction.

  20. Phosphogenesis at a Cretaceous methane seep from New Zealand

    NASA Astrophysics Data System (ADS)

    Zwicker, Jennifer; Steindl, Florian; Smrzka, Daniel; Böttcher, Michael; Gier, Susanne; Kiel, Steffen; Peckmann, Jörn

    2016-04-01

    Phosphate-rich deposits have been a topic of intense research for decades. The process of phosphogenesis is mainly observed in marine sediments of coastal upwelling zones, where organic matter delivers sufficient phosphorus (P) to enable the formation of phosphorites. As P may be cycled within marine sediments on short timescales, only specific geochemical conditions allow for the precipitation and preservation of phosphate minerals. The processes that enable phosphogenesis are still a matter of debate, and not all mechanisms involved are fully understood. We expand the scope of known phosphorous-rich deposits further, with evidence of phosphogenesis at methane seeps. Cretaceous methane-seep limestones from Waipiro Bay, New Zealand, exhibit (1) a matrix composed of cryptocrystalline fluorapatite in between micritic spheroids and coated calcite grains, and (2) phosphatic spheroids within a micritic matrix. Due to the abundant spherical morphologies of phosphate and carbonate grains, and the exceptionally well preserved phosphate matrix, we suggest that their formation was associated with microbial activity. Methane seeps provide ideal conditions for chemosynthetic communities to thrive, and for the growth of bacterial mats at the sediment water interface. To understand these unique deposits, we derive a formation scenario for apatite and spheroidal carbonate, using detailed petrographical observations, X-ray diffraction, scanning electron microscopy, and electron microprobe analyses. Furthermore, it is shown that phase-specific stable carbon and oxygen isotopes confirm that both phosphate and carbonate formation occurred at a methane seep.

  1. Important geological and biological impacts of natural hydrocarbon seeps: Northern Gulf of Mexico continental slope

    SciTech Connect

    Roberts, H.H. )

    1993-11-01

    Large volumes of siliciclastic sediments, input especially during periods of lowered sea level, and compensating salt tectonics have produced a continental slope that is arguably the most complex in today's oceans. Faults associated with deformation of salt and shale provide the primary migration routes for hydrocarbon gases, crude oil, brines, and formation fluids to the modern sea floor. Since the mid 1980s, it has become increasingly clearer that this process has an extremely important impact on the geomorphology, sedimentology, and biology of the modern continental slope. Hydrocarbon source, flux rate, and water depth are important determinants of sea-floor response. Under rapid flux conditions mud volcanoes (to 1 km wide and 50 m high) result, and hydrate hills (rich with authigenic carbonates), carbonate lithoherms, and isolated communities of chemosymbiotic organisms with associated hardgrounds represent much slower flux responses. In numerous moderate- to low-flux cases, cold seep products function to support islands of productivity for communities of chemosymbiotic organisms that contribute both directly (shell material) and through chemical byproducts to the production of massive volumes of calcium-magnesium carbonate in the form of hardgrounds, stacked slabs, and discrete moundlike buildups (commonly >20m). Seep-related carbonates of the Gulf of Mexico continental slope, as well those formed through degassing of accretionary prisms along active margins, are now thought to create hardgrounds and discrete buildups that are excellent analogs for many problematic carbonate buildups in ancient deep-water siliciclastic rocks.

  2. The SEDIBUD (Sediment Budgets in Cold Environments) Programme: Current activities and future key tasks

    NASA Astrophysics Data System (ADS)

    Beylich, A. A.; Lamoureux, S. F.; Decaulne, A.

    2012-04-01

    Projected climate change in cold regions is expected to alter melt season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. Similarly, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. These effects will undoubtedly change surface environments in cold regions and alter the fluxes of sediments, nutrients and solutes, but the absence of quantitative data and coordinated process monitoring and analysis to understand the sensitivity of the Earth surface environment is acute in cold climate environments. The International Association of Geomorphologists (I.A.G./A.I.G.)SEDIBUD (Sediment Budgets in Cold Environments) Programme was formed in 2005 to address this existing key knowledge gap. SEDIBUD currently has about 400 members worldwide and the Steering Committee of this international programme is composed of ten scientists from eight different countries: Achim A. Beylich (Chair) (Norway), Armelle Decaulne (Secretary) (France), John C. Dixon (USA), Scott F. Lamoureux (Vice-Chair) (Canada), John F. Orwin (Canada), Jan-Christoph Otto (Austria), Irina Overeem (USA), Thorsteinn Saemundsson (Iceland), Jeff Warburton (UK), Zbigniew Zwolinski (Poland). The central research question of this global group of scientists is to: Assess and model the contemporary sedimentary fluxes in cold climates, with emphasis on both particulate and dissolved components. Initially formed as European Science Foundation (ESF) Network SEDIFLUX (2004-2006), SEDIBUD has further expanded to a global group of researchers with field research sites located in polar and alpine regions in the northern and southern hemisphere. Research carried out at each of the close to 50 defined SEDIBUD key test sites varies by programme, logistics and available resources, but typically represent interdisciplinary collaborations of

  3. Seep-carbonate lamination controlled by cyclic particle flux

    NASA Astrophysics Data System (ADS)

    Himmler, Tobias; Bayon, Germain; Wangner, David; Enzmann, Frieder; Peckmann, Jörn; Bohrmann, Gerhard

    2016-11-01

    Authigenic carbonate build-ups develop at seafloor methane-seeps, where microbially mediated sulphate-dependent anaerobic oxidation of methane facilitates carbonate precipitation. Despite being valuable recorders of past methane seepage events, their role as archives of atmospheric processes has not been examined. Here we show that cyclic sedimentation pulses related to the Indian monsoon in concert with authigenic precipitation of methane-derived aragonite gave rise to a well-laminated carbonate build-up within the oxygen minimum zone off Pakistan (northern Arabian Sea). U–Th dating indicates that the build-up grew during past ~1,130 years, creating an exceptional high-resolution archive of the Indian monsoon system. Monsoon-controlled formation of seep-carbonates extends the known environmental processes recorded by seep-carbonates, revealing a new relationship between atmospheric and seafloor processes.

  4. Control of Quaternary sea-level changes on gas seeps

    NASA Astrophysics Data System (ADS)

    Riboulot, Vincent; Thomas, Yannick; Berné, Serge; Jouet, Gwénaël.; Cattaneo, Antonio

    2014-07-01

    Gas seeping to the seafloor through structures such as pockmarks may contribute significantly to the enrichment of atmospheric greenhouse gases and global warming. Gas seeps in the Gulf of Lions, Western Mediterranean, are cyclical, and pockmark "life" is governed both by sediment accumulation on the continental margin and Quaternary climate changes. Three-dimensional seismic data, correlated to multi-proxy analysis of a deep borehole, have shown that these pockmarks are associated with oblique chimneys. The prograding chimney geometry demonstrates the syn-sedimentary and long-lasting functioning of the gas seeps. Gas chimneys have reworked chronologically constrained stratigraphic units and have functioned episodically, with maximum activity around sea level lowstands. Therefore, we argue that one of the main driving mechanisms responsible for their formation is the variation in hydrostatic pressure driven by relative sea level changes.

  5. Seep-carbonate lamination controlled by cyclic particle flux

    PubMed Central

    Himmler, Tobias; Bayon, Germain; Wangner, David; Enzmann, Frieder; Peckmann, Jörn; Bohrmann, Gerhard

    2016-01-01

    Authigenic carbonate build-ups develop at seafloor methane-seeps, where microbially mediated sulphate-dependent anaerobic oxidation of methane facilitates carbonate precipitation. Despite being valuable recorders of past methane seepage events, their role as archives of atmospheric processes has not been examined. Here we show that cyclic sedimentation pulses related to the Indian monsoon in concert with authigenic precipitation of methane-derived aragonite gave rise to a well-laminated carbonate build-up within the oxygen minimum zone off Pakistan (northern Arabian Sea). U–Th dating indicates that the build-up grew during past ~1,130 years, creating an exceptional high-resolution archive of the Indian monsoon system. Monsoon-controlled formation of seep-carbonates extends the known environmental processes recorded by seep-carbonates, revealing a new relationship between atmospheric and seafloor processes. PMID:27876764

  6. Seep-carbonate lamination controlled by cyclic particle flux.

    PubMed

    Himmler, Tobias; Bayon, Germain; Wangner, David; Enzmann, Frieder; Peckmann, Jörn; Bohrmann, Gerhard

    2016-11-23

    Authigenic carbonate build-ups develop at seafloor methane-seeps, where microbially mediated sulphate-dependent anaerobic oxidation of methane facilitates carbonate precipitation. Despite being valuable recorders of past methane seepage events, their role as archives of atmospheric processes has not been examined. Here we show that cyclic sedimentation pulses related to the Indian monsoon in concert with authigenic precipitation of methane-derived aragonite gave rise to a well-laminated carbonate build-up within the oxygen minimum zone off Pakistan (northern Arabian Sea). U-Th dating indicates that the build-up grew during past ~1,130 years, creating an exceptional high-resolution archive of the Indian monsoon system. Monsoon-controlled formation of seep-carbonates extends the known environmental processes recorded by seep-carbonates, revealing a new relationship between atmospheric and seafloor processes.

  7. A biogeographic network reveals evolutionary links between deep-sea hydrothermal vent and methane seep faunas.

    PubMed

    Kiel, Steffen

    2016-12-14

    Deep-sea hydrothermal vents and methane seeps are inhabited by members of the same higher taxa but share few species, thus scientists have long sought habitats or regions of intermediate character that would facilitate connectivity among these habitats. Here, a network analysis of 79 vent, seep, and whale-fall communities with 121 genus-level taxa identified sedimented vents as a main intermediate link between the two types of ecosystems. Sedimented vents share hot, metal-rich fluids with mid-ocean ridge-type vents and soft sediment with seeps. Such sites are common along the active continental margins of the Pacific Ocean, facilitating connectivity among vent/seep faunas in this region. By contrast, sedimented vents are rare in the Atlantic Ocean, offering an explanation for the greater distinction between its vent and seep faunas compared with those of the Pacific Ocean. The distribution of subduction zones and associated back-arc basins, where sedimented vents are common, likely plays a major role in the evolutionary and biogeographic connectivity of vent and seep faunas. The hypothesis that decaying whale carcasses are dispersal stepping stones linking these environments is not supported.

  8. Biogeochemical investigations of marine methane seeps, Hydrate Ridge, Oregon

    NASA Astrophysics Data System (ADS)

    Valentine, David L.; Kastner, Miriam; Wardlaw, George D.; Wang, Xuchen; Purdy, Alexandra; Bartlett, Douglas H.

    2005-12-01

    A series of biogeochemical studies were conducted at the southern summit of Hydrate Ridge, offshore Oregon. Using the submersible DSV Alvin, sediment push cores were collected from two distinct seep environments characterized by the presence of clam fields (CF) or microbial mats (MM) at the sediment-water interface; samples were also collected from a nearby reference site characterized by a barren surface at the sediment-water interface. Sediment samples from each setting were analyzed for the depth distributions of total organic carbon (concentrations, δ13C and Δ14C), total sedimentary nitrogen, and microbial abundance. Pore fluids were extracted and analyzed for sulfate, alkalinity, sulfide, organic carbon, and volatile organic acids. These depth distributions clearly indicate the presence of three distinctive biogeochemical settings in the surface sediments of Hydrate Ridge, and provide the basis for a comparative biogeochemical analysis. Both CF and MM sites display properties indicating enhanced microbial activity in the subsurface, compared with the reference site. MM sites display evidence of net biomass production in the subsurface; however, a loss of sediment nitrogen relative to the reference site indicates that mineralization is also enhanced. Calculations based on the removal of nitrogen indicate that greater than 30% of autochthonous organic material is lost to enhanced mineralization in the top 23 cm of one MM site. An isotope mass balance of sediment-bound organic carbon indicates a mixed source, including methane and allochthonous organic carbon dissolved in the seep fluids. The concentrations of organic carbon dissolved in seep fluids reach values of 22 mM and provide a first indication that advective transport of dissolved organic carbon from great depth may supply an important source of energy and carbon to "methane seep" communities.

  9. Improved Detection and Mapping of Deepwater Hydrocarbon Seeps: Optimizing Acquisition and Processing Parameters for Marine Seep Hunting

    NASA Astrophysics Data System (ADS)

    Mitchell, G. A.; Orange, D.; Gharib, J. J.; Saade, E. J.; Joye, S. B.

    2016-12-01

    Marine seep hunting surveys are a current focus of hydrocarbon exploration due to recent advances in offshore geophysical and geochemical technologies. Hydrocarbon seeps are ephemeral, small, discrete, and often difficult to sample on the deep seafloor. Low to mid-frequency multibeam echosounders (MBES) are an ideal exploration tool to remotely locate and map seafloor features associated with seepage. Geophysical signatures from hydrocarbon seeps are evident in bathymetric datasets (fluid expulsion features), seafloor backscatter datasets (carbonate outcrops, gassy sediments, methane hydrate deposits), and midwater backscatter datasets (gas bubble and oil droplet plumes). Interpretation of these geophysical seep signatures in backscatter datasets is a fundamental component in seep hunting. Degradation of backscatter datasets resulting from environmental, geometric, and system noise can interfere with the detection and delineation of seeps. We present a backscatter intensity normalization method and a 2X acquisition technique that can enhance the geologic resolvability within backscatter datasets and assist in interpretation and characterization of seeps. We use GC600 in the Northern Gulf of Mexico as a seep calibration site for a Kongsberg EM302 30 kHz MBES prior to the start of the Gigante seep hunting survey. We analyze the results of a backscatter intensity normalization, assess the effectiveness of 2X seafloor coverage in resolving geologic features in backscatter data, and determine off-nadir detection limits of bubble plumes. GC600's location and robust venting make it a natural laboratory in which to study natural hydrocarbon seepage. The site has been the focus of several near-seafloor surveys as well as in-situ studies using advanced deepwater technologies analyzing fluid flux and composition. These datasets allow for ground-truthing of our remote backscatter measurements prior to commencing exploration within the frontier regions of the Southern Gulf of

  10. Estimation of past intermittent methane seep activity using radiocarbon dating of Calyptogena shells in the eastern Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Yagasaki, K.; Ashi, J.; Yokoyama, Y.; Miyairi, Y.; Kuramoto, S.

    2013-12-01

    Radioisotope carbon dating samples from the deep ocean has always been a difficult phenomenon due to the carbon offset present. This research presents a way of utilizing such method to date shell samples in order to study past fault activities. The research presented will be based on the preliminary data collected thus far. The Nankai and the Tokai regions are common areas for cold seeps, where seepage of hydrogen sulfide and methane rich fluid occurs. These various substances encourage the growth of Calyptogena colonies to flourish at these sites. Cold seeps generally occur at tectonically active continental margins and are mostly ephemeral. This suggests that the cold seep events are possibly influenced by the tectonic activity during the plate divergence. In 1997, a submersible dive by Shinkai 2000 discovered an unusually large Calyptogena colony ranging over 200 m2 off Daini Tenryu Knoll. Majority of the shells were fossilized with few live shells remaining. It is assumed that past tectonic events in the region may have caused a high flux of methane fluid or gas to be released, making it possible to support such a vast scale colony to survive until their eventual death. Previous attempt to reconstruct the cold seep activity history through amino acid racemisation dating revealed two different age grouped shells. Further data using a different method is required to prove its reliability, as acid racemization dating technique can easily be affected by seawater temperature changes and microbial activity. This consequently alters the protein structure of the sample and its overall age. As 14C radioisotope dating is not affected by temperature change, it will provide additional information to the accuracy of the acid racemisation dating of the shell. However, the possibility of contamination is likely due to the shells incorporating older carbon from the sediments during their early stages of growth. The old carbon value can be calculated by subtracting the formerly

  11. Turbine tent measurements of marine hydrocarbon seeps on subhourly timescales

    NASA Astrophysics Data System (ADS)

    Leifer, Ira; Boles, Jim

    2005-01-01

    Three turbine seep-tents simultaneously measured marine seep gas fluxes with high time resolution (0.2 s) at multiple locations. Tents were inverted polyvinyl cones, 2-m diameter, 1-m tall, and weighted on their lower skirt edges. Rising gas bubbles induce vertical fluid motions, which were measured by laboratory-calibrated turbines in chimneys on top of the tents. Initial deployment was at an active seep area in the Coal Oil Point seep field, in the Santa Barbara Channel, California. The three tents simultaneously collected data for continuous time periods of 2 hours in both the morning and afternoon. Seabed temperature and pressure were acquired every 3 s over the same time periods as the flux measurements from a conductivity temperature depth, CTD, mounted on one tent. Results strongly suggest that oceanic swell had a significant forcing effect on the flux at a subhourly timescale. There was an inverse relationship between effect of swell height on the flux and flux. Swells from 1 to 4 m height and periodicities of 7 and 12 s caused variations of ˜1% to 4% from the average flux. Proposed mechanisms to explain the observations are diffusion with surrounding sediments, termed gas charging, swell induced changes in fracture size, termed fracture forcing, and swell induced vent activation/deactivation, termed pore activation. On the basis of the seep frequency response, we propose pore activation was dominant.

  12. The SEDIBUD (Sediment Budgets in Cold Environments) Programme: Ongoing activities and selected key tasks for the coming years

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Lamoureux, Scott F.; Decaulne, Armelle

    2012-09-01

    Projected climate change in cold environments is expected to alter melt-season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. In addition, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. The combined effects of these changes will alter surface environments in cold climate regions and change the fluxes of sediments, nutrients and solutes, but the absence of data, coordinated process monitoring and coordinated quantitative analysis to understand the sensitivity of the Earth surface environment are acute in cold climate environments. The International Association of Geomorphologists (I.A.G./A.I.G.) SEDIBUD (Sediment Budgets in Cold Environments) Programme has been formed to address this key knowledge gap and builds on the earlier European Science Foundation (ESF) SEDIFLUX (Sedimentary Source-to-Sink-Fluxes in Cold Environments) Network. Coordinated efforts are carried out to monitor, quantify, compare and model sedimentary fluxes and possible effects of predicted climate change in currently 44 selected SEDIBUD Key Test Sites (cold climate environment catchments) worldwide.

  13. Thermophilic nitrate-reducing microorganisms prevent sulfate reduction in cold marine sediments incubated at high temperature

    NASA Astrophysics Data System (ADS)

    Nepomnyashchaya, Yana; Rezende, Julia; Hubert, Casey

    2014-05-01

    Hydrogen sulphide produced during metabolism of sulphate-reducing microorganisms (SRM) is toxic, corrosive and causes detrimental oil reservoir souring. During secondary oil recovery, injecting oil reservoirs with seawater that is rich in sulphate and that also cools high temperature formations provides favourable growth conditions for SRM. Nitrate addition can prevent metabolism of SRM by stimulating nitrate-reducing microorganisms (NRM). The investigations of thermophilic NRM are needed to develop mechanisms to control the metabolism of SRM in high temperature oil field ecosystems. We therefore established a model system consisting of enrichment cultures of cold surface marine sediments from the Baltic Sea (Aarhus Bay) that were incubated at 60°C. Enrichments contained 25 mM nitrate and 40 mM sulphate as potential electron acceptors, and a mixture of the organic substrates acetate, lactate, propionate, butyrate (5 mM each) and yeast extract (0.01%) as potential carbon sources and electron donors. Slurries were incubated at 60°C both with and without initial pasteurization at 80°C for 2 hours. In the enrichments containing both nitrate and sulphate, the concentration of nitrate decreased indicating metabolic activity of NRM. After a four-hour lag phase the rate of nitrate reduction increased and the concentration of nitrate dropped to zero after 10 hours of incubation. The concentration of nitrite increased as the reduction of nitrate progressed and reached 16.3 mM after 12 hours, before being consumed and falling to 4.4 mM after 19-day of incubation. No evidence for sulphate reduction was observed in these cultures during the 19-day incubation period. In contrast, the concentration of sulphate decreased up to 50% after one week incubation in controls containing only sulphate but no nitrate. Similar sulfate reduction rates were seen in the pasteurized controls suggesting the presence of heat resistant SRM, whereas nitrate reduction rates were lower in the

  14. Active seepage and water infiltration in Lake Baikal sediments: new thermal data from TTR-Baikal 2014 (Class@Baikal)

    NASA Astrophysics Data System (ADS)

    Poort, Jeffrey; Khlystov, Oleg M.; Akhmanov, Grigorii G.; Khabuev, Andrei V.; Belousov, Oleg V.

    2015-04-01

    New thermal data from the sediments of Lake Baikal were collected in July 2014 during the first Training-Through-Research cruise on Lake Baikal (Class@Baikal) organized by MGU and LIN. TTR-Baikal is a comprehensive multidisciplinary program to train students on the field on pertinent scientific topics. The cruise program focused on seafloor sampling, acoustic investigations and heat flow measurements of gas seeps, flares, mud volcanoes, slumps and debris flows, canyons and channels in the coastal proximity. The thermal data were acquired using autonomous temperature sensors on a 3 meter long gravity corer that allowed analysis at the same spot of sediments, pore fluids, hydrates and microbiology. A total of eight thermal measurements were performed in five structures located on the lake floor of the Central Baikal Basin at 333-1530 meter water depths: 3 mud volcanoes (Novosibirsk, Unshuy and Krest), 1 seep site (Seep 13), and one fault outcrop in the Selenga transfer zone. All studied structures show signals of active seepage, water infiltration and/or hydrate dynamics. The strongest thermal gradient has been measured in Seep 13, suggesting a strong upflow of warm fluids similar to the Gorevoy Utes seep. At the three mud volcanoes, hydrate presence have been evidenced and both enhanced and reduced thermal gradients have been observed. This is similar to the hydrate-bearing K-2 mud volcano in Baikal (Poort et al., 2012). A strongly reduced thermal gradient was observed in the Krest mud volcano where the presence of oxidized channels at 30-40 cm under the sediment surface indicate an infiltration of cold lake water. The water infiltration process at hydrate bearing seep sites will be discussed and compared with other seep areas in the world.

  15. SEEP II, Shelf Edge Exchange Processes-II: Chlorophyll a fluorescence, temperature, and beam attenuation measurements from moored fluorometers

    SciTech Connect

    Medeiros, W.H.; Wirick, C.D.

    1992-02-01

    The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. The first SEEP experiment (SEEP I) was across the outer continental shelf of New England during 1983--1984 and consisted of a series of nine cruises and a mooring array. The second experiment (SEEP II) focused specifically of the shelf/slope frontal region of the mid-Atlantic Bight off the Delmarva peninsula. This report presents data collected during SEEP II. The SEEP II experiment consisted of a series of ten cruises and mooring arrays as well as over-flights by NASA aircraft. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Hydrographic data were collected on all cruises except SEEP2-04 and SEEP2-07 during which benthic processes were investigated. Mooring arrays were deployed during three cruises in the Spring, Summer and Winter of 1988. Brookhaven National Laboratory deployed sixteen fluorometer instrument packages on their moorings with sensors to measure: the in vivo fluorescence of phytoplankton, temperature, subsurface light, dissolved oxygen, and water transparency. Data from the fluorometer, temperature, and transmissometer sensors are reported herein.

  16. SEEP II, Shelf Edge Exchange Processes-II: Chlorophyll a fluorescence, temperature, and beam attenuation measurements from moored fluorometers

    SciTech Connect

    Medeiros, W.H.; Wirick, C.D.

    1992-02-01

    The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. The first SEEP experiment (SEEP I) was across the outer continental shelf of New England during 1983--1984 and consisted of a series of nine cruises and a mooring array. The second experiment (SEEP II) focused specifically of the shelf/slope frontal region of the mid-Atlantic Bight off the Delmarva peninsula. This report presents data collected during SEEP II. The SEEP II experiment consisted of a series of ten cruises and mooring arrays as well as over-flights by NASA aircraft. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Hydrographic data were collected on all cruises except SEEP2-04 and SEEP2-07 during which benthic processes were investigated. Mooring arrays were deployed during three cruises in the Spring, Summer and Winter of 1988. Brookhaven National Laboratory deployed sixteen fluorometer instrument packages on their moorings with sensors to measure: the in vivo fluorescence of phytoplankton, temperature, subsurface light, dissolved oxygen, and water transparency. Data from the fluorometer, temperature, and transmissometer sensors are reported herein.

  17. Lessons in microbial geochemistry from the Coal Oil Point seep field: progress as prospects.

    NASA Astrophysics Data System (ADS)

    Valentine, D. L.; Kinnaman, F.; Wardlaw, G.; Redmond, M.; Ding, H.; Kimball, J.; Busso, L.; Larson, A.

    2005-12-01

    The hydrocarbon seeps located offshore Coal Oil Point, Santa Barbara, CA, are estimated to emit 1010 grams of methane and 50 thousand barrels of oil annually, and are among the most prolific in the world. The seep field spans a range of shelf depths and many of the seeps are accessible by SCUBA, making this an ideal location to investigate the impact of microbes on the biogeochemical cycling of methane and other hydrocarbons. With funding provided by the National Science Foundation, the Minerals Management Service and the Petroleum Research Fund, we have begun to investigate the interactions between microbes, hydrocarbon distributions, and environmental dynamics in the seep environment. This presentation will provide an overview of Coal Oil Point seep field and the biogeochemical research being conducted there. Several topics will be incorporated including i) the dynamics of oil and gas seepage, ii) the microbial consumption of methane, ethane, propane, butane and crude oil, iii) the distribution and composition of microbial mats, iv) redox differentiation in seep sediments and the importance of advection, and v) the development of experimental tools for the investigation of seep environments. Prospects for future biochemical research in the Coal Oil Point seep field will also be discussed.

  18. Constraining silica diagenesis in methane-seep deposits

    NASA Astrophysics Data System (ADS)

    Smrzka, Daniel; Kraemer, Stephan; Zwicker, Jennifer; Birgel, Daniel; Fischer, David; Kasten, Sabine; Goedert, James; Peckmann, Jörn

    2015-04-01

    Silicified fossils and silicified early diagenetic carbonate minerals as well as authigenic silica phases are common in ancient seep limestones. Silicification of calcareous fossils facilitates the preservation of even fine details and is therefore of great interest to paleontologists, permitting a reliable taxonomic identification of the chemosynthesis-based taxa that lived at ancient hydrocarbon seeps. Four methane-seep limestones of Paleozoic, Mesozoic, and Cenozoic age with abundant silica phases are compared in this study; one, an Eocene seep deposit on the north shore of the Columbia River at Knappton, western Washington State, USA, is described for the first time. Its lithology and fabrics, negative δ13Ccarbonate values as low as -27.6‰, and 13C-depleted biomarkers of archaea involved in the anaerobic oxidation of methane (AOM) reveal that the carbonate rock formed at a methane seep. The background sediments of the studied Phanerozoic seep limestones contain abundant siliceous microfossils, radiolarian tests in case of the Late Carboniferous Dwyka Group deposits from Namibia and the Late Triassic Graylock Butte deposits from eastern Oregon (USA), diatom frustules in case of the Eocene Knappton limestone and an Oligocene seep deposit from the Lincoln Creek Formation (western Washington State, USA). These microfossils are regarded as the source of dissolved silica, causing silicification and silica precipitation. All seep limestones used in this study are characterized by very similar paragenetic sequences. Silicified fossils include brachiopods and worm tubes, silica cements include microquartz, fibrous microcrystalline silica, and megaquartz. The silica cements formed after the AOM-derived cements ceased to precipitate but before equant calcite spar formed. Numerical experiments using the computer code PHREEQC were conducted to test the hypothesis that (1) AOM increases the pH of pore waters and that (2) this pH increase subsequently mobilizes biogenic

  19. Microbial Communities in Methane- and Short Chain Alkane-Rich Hydrothermal Sediments of Guaymas Basin

    PubMed Central

    Dowell, Frederick; Cardman, Zena; Dasarathy, Srishti; Kellermann, Matthias Y.; Lipp, Julius S.; Ruff, S. Emil; Biddle, Jennifer F.; McKay, Luke J.; MacGregor, Barbara J.; Lloyd, Karen G.; Albert, Daniel B.; Mendlovitz, Howard; Hinrichs, Kai-Uwe; Teske, Andreas

    2016-01-01

    The hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, hot sediments (above 60°C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed “Mat Mound”) were characterized by porewater geochemistry of methane, C2–C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas, and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates. PMID:26858698

  20. Microbial Communities in Methane- and Short Chain Alkane-Rich Hydrothermal Sediments of Guaymas Basin.

    PubMed

    Dowell, Frederick; Cardman, Zena; Dasarathy, Srishti; Kellermann, Matthias Y; Lipp, Julius S; Ruff, S Emil; Biddle, Jennifer F; McKay, Luke J; MacGregor, Barbara J; Lloyd, Karen G; Albert, Daniel B; Mendlovitz, Howard; Hinrichs, Kai-Uwe; Teske, Andreas

    2016-01-01

    The hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, hot sediments (above 60°C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed "Mat Mound") were characterized by porewater geochemistry of methane, C2-C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas, and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates.

  1. Hyperspectral Imaging of a Chemosynthetic Seep System in the Panoche Hills, California: A Possible Terrestrial Analog for Mixed Carbonate-Silicate Deposits on Mars

    NASA Astrophysics Data System (ADS)

    Schneider, E. J.; Moore, J. C.; Schwartz, H.; Silver, E.

    2004-12-01

    Chemosynthetic communities and carbonate substrate forming at cold seeps represent a unique ecosystem for studying life in extreme environments, such as Mars. Carbonate hardgrounds form due to the upward seepage of bicarbonate saturated fluid derived from methane oxidation. Carbonates can precipitate in the subsurface, resulting in high preservation potential. In the Panoche Hills of California, carbonate seep deposits contain fossilized chemosynthetic organisms and have negative carbon isotopic compositions, similar to other ancient cold seep deposits. The carbonates occur as mounds, concretions and pavements. The carbonate seep deposits of the Panoche Hills have been mapped in detail in the central portion of the field area and identified in the northern portion. These carbonates are well exposed, which make them good targets for remote sensing. Our remote sensing information is a 2 km by 8 km swath of HyMap hyperspectral data centered on the geologically well-mapped area. HyMap has 126 bands from visible to short wave infrared wavelengths (0.45 to 2.5 ƒYm). Carbonates have a diagnostic absorption feature at 2.34 ƒYm, within the range of HyMap¡¦s accuracy. Further, the carbonate seeps measure up to 10 meters across, and are detectable with HyMap¡¦s spatial resolution of 3-meter pixels. The methane derived carbonates of the Panoche Hills formed below the sediment-water interface and incorporated a significant amount of silicate minerals, complicating the spectral identification of carbonate. Spectra and GPS locations collected in the field provided data for comparison and helped to classify carbonates associated with siliciclastic material. A spectral library, based on field spectra, was used as input for classifying with ENVI remote sensing software. The successful inputs applied to the data set found potential unmapped carbonate localities as well as correct identification of previously mapped locations. Spectroscopic investigations on Mars suggest the

  2. Resistivity structure of the Del Mar methane seep.

    NASA Astrophysics Data System (ADS)

    Kannberg, P. K.; Constable, S.

    2015-12-01

    In March of 2015 we mapped the resistivity structure of the Del Mar methane seep in the inner California borderlands using a deep towed electromagnetic (EM) source and receiver array. Located in the San Diego trough at a depth of 1km, the seep site is on the flank of a mound associated with a transpressive step in the San Diego trough fault. The seep site has previously been associated with seafloor pockmarks, acoustic wipeouts, chemosynthetic communities, and active methane bubble venting. Controlled source electromagnetic (CSEM) surveys are performed by deep-towing an EM source that is transmitting a known signal; this signal is detected by towed receivers. This transmitted signal is altered by the electrical properties of the surrounding environment. Compared to seismic methods, EM methods are largely insensitive to free gas, making it an especially useful tool for detecting electrically resistive methane hydrate in areas of active gas venting. We used a 50m dipole transmitting 100A, with 3-axis electric field receivers spaced at 130m, 230m, 330m, and 430m behind the transmitter dipole center. The receiver data are inverted using MARE2DEM, a finite element 2D inversion routine. The inversion results show the background resistivity of the trough sediments to be about 1-2 ohmm, and are largely featureless outside of the seep site. However at the seep site we see a decanter-shaped 100 ohmm resistor whose base is 100m below the seafloor, and 1km wide at its widest. This feature narrows at the top to form a pipe structure about 200m wide that extends to the seafloor. These resistive structures are interpreted to be methane hydrate resulting from methane rich fluid flow along faults associated with the transpressional system that brackets the seep site.

  3. Significance of aragonite cements around Cretaceous marine methane seeps

    SciTech Connect

    Savard, M.M.; Beauchamp, B.; Veizer, J.

    1996-05-01

    Detailed petrography and geochemistry of carbonate precipitates in Cretaceous cold seep mounds from the Canadian Arctic show spectacular early diagenetic products: some still-preserved splays and isopachous layers of fine, acicular aragonite, and large botryoids and crusts of low-magnesium calcite showing unusual entanglement of former fibrous calcite and aragonite. The latter mineralogy is suggested by clear, flat-terminated cathodoluminescence patterns interpreted as ancient crystal growth steps, and the former by rhombohedral terminations. The early cement phases very likely precipitated in cold Arctic water dominated by bicarbonates derived from bacterially oxidized methane: these cements have {delta}{sup 13}C values around {minus}44.0% and {delta}{sup 18}O values of 1.8 to 0.1% PDB. Coexistence of calcite and aragonite early cements in the Cretaceous seep mounds is unusual, because precipitation occurred in high-latitude, cold-water settings, and during a so-called calcite sea mode. As in modern marine hydrocarbon seeps, the chemistry of the Cretaceous system was apparently controlled by chemosynthetic bacterial activity, resulting in high a{sub HCO{sub 3}{sup {minus}}} that promoted precipitation of carbonates. The authors suggest that, locally, fluctuations in a{sub HCO{sub 3}{sup {minus}}}/a{sub SO{sub 4}{sup 2{minus}}} resulted in oscillating aragonite or calcite supersaturation, and hence, controlled the mineralogy of the early precipitates.

  4. Carbonate-cemented hardgrounds: a subtle indicator for seep activity offshore Humboldt Bay

    NASA Astrophysics Data System (ADS)

    Shapiro, R. S.; Bazard, D.

    2007-12-01

    Active hydrocarbon seeps are common in the accretionary prism of the Cascadia subduction zone. In Humboldt County, California, the prism is exposed at the surface as a series of fault-propagated anticlines trending NW-SE. Offshore of the town of Samoa, a northwest-plunging anticline is breached at approximately 40 meters water depth, allowing hydrocarbons to seep out to the seafloor (40.8° N, 124.25° W). The assumed microbial activity at the seep leads to the production of interstitial carbonate cements forming hardgrounds. Cementation is pervasive and blocks eroded from the seep area of the seabed are transported onshore during storm events. Blocks collected from the beach range from 3--40 centimeters across. The sediments of the blocks are palimpsest transgressive deposits composed mostly of immature fine sand, but ranging from very fine to rounded gravels 4 cm diameter. Cementation is not dependent on grain size as all of the sediment sizes are cemented. In rare void spaces, a concentric banding of cements is obvious. The interstitial cements preserve original sedimentary structures including graded beds and high-angle cross-beds. Centimeter-scale subspherical concretions occur on the undersides of some blocks. There is no disruption of bedding in contrast to other seeps where the expulsion of gas can create pockmarks, brecciation, and other disturbances. Unlike the better studied seeps farther south in the Eel River basin, the Samoa seeps do not seem to host a rich chemosynthetic fauna. Whole and (mostly) fragmented shells preserved by the cemented sands represent a typical benthic inner shelf community including Dendraster, Macoma, and Olivella. Burrows preserved in the sands are largely horizontal and 1--2 mm diameter. Seep carbonate-cemented hardgrounds are less well studied then the more obvious meter-scale 'chemoherm' deposits. However, they may be more prevalent in the rock record and provide a new proxy for locating ancient seeps and hydrocarbon

  5. SeepC: Preliminary Characterization of Atlantic Margin Seep Ecosystems from Norfolk Canyon to New England Seep Sites.

    NASA Astrophysics Data System (ADS)

    Turner, P. J.; Ball, B.; Cole, E.; LaBella, A.; Wagner, J.; Van Dover, C. L.; Skarke, A. D.; Ruppel, C. D.

    2015-12-01

    Since 2013, more than 500 seep sites have been located along the continental margin of the eastern US using acoustic signals of gas plumes in the water column. During a July 2015 R/V Atlantis expedition, scientists used the submersible Alvin to explore seep sites at depths of 300 to 1500 m. Study sites ranged from Norfolk Canyon north to New England Seep 2 and included Baltimore, Veatch, and Shallop Canyon sites, as well as new unnamed sites between Norfolk and Baltimore Canyons. Mussels dominated the seep sites (cf ''Bathymodiolus'' childressi) but only small populations (<10s of individuals) were observed at seep sites associated with Shallop Canyon. B. heckerae, the dominant mussel at the Blake Ridge and Cape Fear seep sites (sites associated with salt diapirs off the Carolinas), appear to be present at only one of the Atlantic Margin seeps. At the Norfolk Canyon site, dead B. heckerae shells were observed and live individuals may be within the explored area. The abundant vesicomyid clam of Blake Ridge and Cape Fear sites was absent at the continental margin seeps. Apart from B. childressi, the most conspicuous megafaunal invertebrate species at the newly explored seeps was the red crab, Chaceon sp. and the rock crab, Cancer sp. These crabs are not seep endemic but they were especially abundant at the seeps and were observed to feed and mate on the seep grounds. Molecular tools will be used to explore the genetic structure of mussel populations from Norfolk to New England seeps, and stable isotope methods will be used to test for differences among sites in the source of carbon used by mussels. Alvin video transects and photo-mosaics will be used to collect data on macrofauna associated with seeps and to test the hypothesis that shallow seeps (300-500m) support more diverse assemblages than deep sites (1000-1500m).

  6. Cloning and characterization of a new cold-active lipase from a deep-sea sediment metagenome.

    PubMed

    Jeon, Jeong Ho; Kim, Jun-Tae; Kim, Yun Jae; Kim, Hyung-Kwoun; Lee, Hyun Sook; Kang, Sung Gyun; Kim, Sang-Jin; Lee, Jung-Hyun

    2009-01-01

    To search for new cold-active lipases, a metagenomic library was constructed using cold-sea sediment samples at Edison Seamount and was screened for lipolytic activities by plating on a tricaprylin medium. Subsequently, a fosmid clone was selected, and the whole sequence of 36 kb insert of the fosmid clone was determined by shotgun sequencing. The sequence analysis revealed the presence of 25 open reading frames (ORF), and ORF20 (EML1) showed similarities to lipases. Phylogenetic analysis of EML1 suggested that the protein belonged to a new family of esterase/lipase together with LipG. The EML1 gene was expressed in Escherichia coli, and purified by metal-chelating chromatography. The optimum activity of the purified EML1 (rEML1) occurred at pH 8.0 and 25 degrees C, respectively, and rEML1 displayed more than 50% activity at 5 degrees C. The activation energy for the hydrolysis of olive oil was determined to be 3.28 kcal/mol, indicating that EML1 is a cold-active lipase. rEML1 preferentially hydrolyzed triacylglycerols acyl-group chains with long chain lengths of > or = 8 carbon atoms and displayed hydrolyzing activities toward various natural oil substrates. rEML1 was resistant to various detergents such as Triton X-100 and Tween 80. This study represents an example which developed a new cold-active lipase from a deep-sea sediment metagenome.

  7. New gastropods from deep-sea hydrocarbon seeps off West Africa

    NASA Astrophysics Data System (ADS)

    Warén, Anders; Bouchet, Philippe

    2009-12-01

    Thirteen new species of gastropods are described from the Zairov 1-2 and Biozaire 1-3 cruises to the methane seeps off the Congo River: Patellogastropoda: Paralepetopsis sasakii sp. nov. (Neolepetopsidae); Cocculiniformia: Pyropelta oluae sp. nov. and P. sibuetae sp. nov. (Pyropeltidae); Tentaoculus granulatus sp. nov. (Pseudococculinidae); Neomphalina: Leptogyra costellata sp. nov. (Family uncertain); Vetigastropoda: Puncturella similis sp. nov. (Fissurellidae); Lepetodrilus shannonae sp. nov. (Lepetodrilidae); Caenogastropoda: Provanna reticulata sp. nov. and P. chevalieri sp. nov., Cordesia provannoides gen. et sp. nov. (Provannidae); Phymorhynchus coseli sp. nov. and P. cingulata sp. nov. (Conidae); Heterobranchia: Hyalogyrina rissoella sp. nov. (Hyalogyrinidae). All species except T. granulatus (from a settlement trap) belong to groups known from cold seeps and the entire seep fauna here is new to science. Biogeographical affinity of this gastropod fauna is to the West Atlantic seeps, not to the Mediterranean seeps or Mid-Atlantic vents. Fragments of the autecology of the species are presented. The evolution of the seep gastropod fauna is briefly discussed and a continuous immigration of taxa is supported. The oldest verified occurrences of modern taxa in the seeps date back to Cenomanian (Cretaceous) time, while some taxa seem not to appear until very late Tertiary.

  8. Discriminating streambed groundwater influx from bank groundwater seeps as a control on endangered mussel habitat

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Voytek, E. B.; Rosenberry, D. O.; Day-Lewis, F. D.; Lane, J. W.

    2012-12-01

    Groundwater inflow to streams, both through bank seeps and upward streambed flux, can impart a strong control on stream ecosystem dynamics by affecting water chemistry and temperature. During summer, the stable, cold-water refugia produced by groundwater influx are critical to the survival of many freshwater aquatic organisms during low flow conditions. For example, populations of Uniodid mussels are in decline worldwide due to a variety of anthropogenic factors, with the dwarf wedgemussel (Alasmidonta heterodon), native to the northeastern United States, listed as federally endangered since 1990. Preliminary data indicate that dwarf wedgemussel populations survive in the upper streambed in areas that have been qualitatively identified as potential groundwater influx zones. Because the mussels spend much of their life cycle embedded within the upper 5 cm of river substrate it is unknown which process provides the most favorable conditions: the plumes (~17° C) of water emanating from discrete bank seeps along the shoreline, or upward groundwater flux directly through the streambed. Here, we seek to identify which mechanism of groundwater influx to the river may be the dominant mechanism controlling the distribution of dwarf wedgemussels at two influx sites in the upper Delaware River between New York state and Pennsylvania. To address this question, we installed five high spatial resolution (1.4 cm) fiber-optic distributed temperature sensors vertically through the water column and into the streambed along two transects (parallel and normal to the bank) adjacent to a discrete bank seep where dwarf wedgemussels have been identified. The data revealed complex thermal dynamics with an unmixed groundwater plume (often at least 10° C colder than mixed surface water) extending along the streambed/water-column interface to at least 6 m from the bank. At times the plume was colder than both the sediment beneath and the water column above. The plume diminished in vertical

  9. Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard.

    PubMed

    Hryniewicz, Krzysztof; Little, Crispin T S; Nakrem, Hans Arne

    2014-09-02

    The bivalve fauna from the latest Jurassic-earliest Cretaceous hydrocarbon seep deposits from central Spitsbergen, Svalbard comprises at least 17 species, four of which belong to chemosymbiotic taxa often found at seeps. These are the solemyid Solemya (Petrasma) cf. woodwardiana; Nucinella svalbardensis sp. nov., which belongs to a group of large Nucinella species known from seeps and deep water environments; the lucinid bivalve, Tehamatea rasmusseni sp. nov., included in a genus widely distributed in other Jurassic-Cretaceous seeps; and Cretaxinus hurumi gen. et sp. nov., which is the oldest known thyasirid and is discussed in relation to other large seep-restricted genera in this family. The remaining species in the fauna belong to 'background' genera known from coeval normal marine sediments, mostly from the Boreal area. These include the nuculid Dacromya chetaensis, two new malletiids (Mesosaccella rogovi sp. nov. and M. toddi sp. nov.), the oxytomiid Oxytoma octavia, at least three Buchia species, at least two pectinids, including Camptonectes (Costicamptonectes) aff. milnelandensis and Camptonectes (Camptochlamys) clatrathus, the limid Pseudolimea arctica, the arcticid Pseudotrapezium aff. groenlandicum, and the pholadomyid Goniomya literata. The large number of 'background' species in the bivalve fauna is probably a reflection of the shallow-water setting of the Svalbard seeps. This might also explain the lack of the seep-restricted modiomorphid bivalve Caspiconcha from the fauna. With solemyids, Nucinella, lucinids and thyasirids, the latest Jurassic-earliest Cretaceous bivalve seep fauna of Svalbard contains typical representatives of the Mesozoic bivalve seep faunas, both long established and young evolutionary colonists.

  10. Sediment dynamics of a sandy contourite: the sedimentary context of the Darwin cold-water coral mounds, Northern Rockall Trough

    NASA Astrophysics Data System (ADS)

    Huvenne, V. A. I.; Masson, D. G.; Wheeler, A. J.

    2009-06-01

    Grainsize, mineralogy and current-meter data from the Northern Rockall Trough are presented in order to characterise the sandy contourite that forms the sedimentary environment of the Darwin cold-water coral mounds, and to investigate the impact of this environment on the mound build-up. Large clusters of small cold-water coral mounds, 75 m across and 5 m high, have been found southwest of the Wyville Thomson Ridge, at 900-1,100 m water depth. Their present-day sedimentary environment consists of a subtly sorted sandy contourite, elongated NE-SW, roughly parallel to the contours. Critical erosional and depositional current speeds were calculated, and trends in both the quartz/feldspar and foraminifera fractions of the sands show a bi-directional fining from bedload/erosion-dominated sands in the NE to suspension/deposition-dominated sediments in the SW and towards the S (downslope). This is caused by a gradual reduction in governing current speed, linked to a reduction in slope gradient, and by the increasing distance from the current core in the downslope direction. No specific characteristics were found distinguishing the mound sediments from the surrounding sands: they fit in the overall spatial pattern. Some mound cores show hints of a fining-upward trend. Overall the mound build-up process is interpreted as a result of sediment baffling.

  11. Authigenic minerals related to carbon and sulfur biogeochemical cycling from deep-sea active methane seeps offshore South-West Africa

    NASA Astrophysics Data System (ADS)

    Pierre, C.; Blanc-Valleron, M.; Demange, J.; Boudouma, O.; Pape, T.; Himmler, T.; Fekete, N.; Spiess, V.

    2011-12-01

    in cold seep systems where the anoxic-oxic boundary may move within the sediment due to variations in the strength of the methane flux.

  12. Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

    NASA Astrophysics Data System (ADS)

    Wehrmann, L. M.; Knab, N. J.; Pirlet, H.; Unnithan, V.; Wild, C.; Ferdelman, T. G.

    2009-04-01

    Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmol S cm-3 d-1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH2O groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23-18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments.

  13. Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

    NASA Astrophysics Data System (ADS)

    Wehrmann, L. M.; Knab, N. J.; Pirlet, H.; Unnithan, V.; Wild, C.; Ferdelman, T. G.

    2008-12-01

    Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.2 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmolS cm-3 d-1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in -CH2O- groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Iron reduction linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23-18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments.

  14. Analysis of metals in marine sediments by microwave extraction and flame, hydride generation and cold vapor atomic-absorption spectrometry

    SciTech Connect

    Martinez-Garcia, M.L.; Zubieta, A.C.; Lorenzo, S.M.; Lopez-Mahia, P.; Rodriguez, D.P.

    1999-01-01

    A simple and fast metal extraction method that combines closed vessels and microwave heating for the simultaneous extraction of ten selected heavy metals (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Zn) from marine sediments is proposed. Digestion conditions, i.e., power and times microwave irradiation, reagent extractant, sample amount, were optimized to recover the potentially available metallic fraction not bound in silicates. A nitric acid and two step microwave program was established. The resulting solutions were analyzed by flame (FAAS), hydride generation (HG-AAS) and cold vapor (CV-AAS) atomic absorption spectrometry. Quantifications were made using direct calibration with aqueous standards. The recoveries of the spiked samples investigated ranged from 89 to 113%. The results obtained from analyzing the BCR certified reference sediment CRM 277 Estuarine Sediment were in good agreement with the certified values (93--105%), except for low values for chromium (79%). The relative standard deviations for the determination of metals were less than 4%. Finally, the technique designed herein was applied to sediment samples from La Coruna estuary, NW Spain.

  15. Evidences of the Presence of Methane Seeps in the Colombian Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Gracia, Adriana; Rangel-Buitrago, Nelson; Sellanes, Javier

    2010-05-01

    For the first time in the southern Caribbean Sea Margin of Colombia (between 450 - 700 m deep) we confirm the presence of methane seep communities near the deltas of the Magdalena and Sinu rivers. Some evidences of the occurrence of those communities include: i) bivalves constituents of marine chemosynthesis-based communities, which are indicators of reducing environments as vesicomyid and lucinid bivalves (Vesicomya caribbea, Calyptogena ponderosa, Ectenagena modioliforma, Lucinoma spp. and Graecina colombiensis), together with the rare solemyid clam Acharax caribbaea, ii) other seep-associated fauna such as the trochid snail Cataegis meroglypta, iii) the first report of vestimentiferan tubeworms for the area and, iv) the presence of authigenic carbonates; these constructions form hard substrates colonized by sessile fauna. Additionally, more than 20 species of benthic non-seep fauna were found associated in the area. The collected fauna exhibits an elevated taxonomic similarity to other modern and fossil seep communities from the Caribbean (Barbados Prism, Gulf of Mexico, Cenozoic seep taxa from Barbados, Trinidad and Venezuela). The presence of these chemosymbiotic species seems to be related to mud diapirism activity in the South West of the Colombian coast, this geologic characteristic indicates tectonic and depositional processes associated with the aforementioned deltas. Further research is necessary to establish biological and geological interactions, geochemical and geophysical controls, and organization of cold seeps communities in this unexplored area of the Caribbean. Keywords: Methane, Chemosynthesis-based communities,Bivalves, Mud diapirs, Colombian Caribbean Sea

  16. Hydrocarbon seep-carbonates of a Miocene forearc (East Coast Basin), North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Campbell, Kathleen A.; Francis, David A.; Collins, Mike; Gregory, Murray R.; Nelson, Campbell S.; Greinert, Jens; Aharon, Paul

    2008-02-01

    An ancient hydrocarbon seep province of 14 isolated, authigenic carbonate deposits has been identified in fine-grained, deep-marine siliciclastic strata of the Miocene East Coast Basin, North Island, New Zealand. These forearc sediments have been uplifted and complexly deformed into accretionary ridges, adjacent to the still-active Hikurangi convergent margin. Older active and passive margin strata (mid-Cretaceous to Oligocene in age) underlie the Neogene sequence, and contain oil- and gas-prone source rocks. Older Mesozoic meta-sedimentary rocks constitute the backstop against which the current phase of subduction-related sedimentation has accumulated (~ 24 Ma-present). The seep-carbonates (up to 10 m thick, 200 m across) archive methane signatures in their depleted carbon isotopes (to δ13C -51.7‰ PDB), and contain chemosynthesis-based paleocommunities (e.g. worm tubes, bathymodioline mussels, and vesicomyid, lucinid and thyasirid bivalves) typical of other Cenozoic and modern seeps. Northern and southern sites are geographically separated, and exhibit distinct lithological and faunal differences. Structural settings are variable. Seep-associated lithologies also are varied, and suggest carbonate development in sub-seafloor, seafloor and physically reworked (diapiric expansion, gas explosion, gravity slide or debris flow) settings, similar to Italian Apennine seep deposits of overlapping ages. Peculiar attributes of the New Zealand Miocene seep deposits are several, including digitate thrombolites of clotted microbial micrite encased in thick, isopachous horizons and botryoids of aragonite. Seep plumbing features are also well-exposed at some sites, displaying probable gas-explosion breccias filled with aragonite, tubular concretions (fluid conduits), and carbonate-cemented, thin sandstone beds and burrows within otherwise impermeable mudstones. A few seeps were large enough to develop talus-debris piles on their flanks, which were populated by lucinid bivalves

  17. Shelf Edge Exchange Processes, II: SEEP2-08, R/V ENDEAVOR cruise 188

    SciTech Connect

    Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

    1989-12-01

    The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984 (Behrens and Flagg, 1986). Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. This project consisted of a series of ten cruises, a mooring array, and a series of over-flights by NASA aircraft. Hydrographic data were collected on eight of the cruises, six of which were primarily mooring deployment or recovery cruises. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Two cruises (SEEP2-04 and SEEP2-07) were dedicated to investigating benthic processes and hydrographic data were not collected.

  18. Shelf Edge Exchange Processes--II: SEEP2-10, R/V ENDEAVOR cruise 195

    SciTech Connect

    Behrens, W.J.; Wilson, C.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

    1990-04-01

    The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. This project consisted of a series of ten cruises, a mooring array, and a series of over-flights by NASA aircraft. Hydrographic data were collected on eight of the cruises, six of which were primarily mooring deployment or recovery cruises. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Two cruises (SEEP2-04 and SEEP2-07) were dedicated to investigating benthic processes and hydrographic data were not collected. The R/V ENDEAVOR cruise 193, SEEP2-09, took place from 2--12 May 1989 and recovered ten mornings along two cross-shelf lines across the outer continental shelf. During this cruise 77 CTD casts were made measuring pressure, temperature, conductivity, dissolved oxygen, fluorescence and light transmission. Discrete samples were taken in rosette-mounted Niskin bottles and analyzed for concentration of nutrients, chlorophyll a, dissolved oxygen, and particulate organic carbon and nitrogen. 14 refs., 9 figs., 3 tabs.

  19. Association of oil seeps and chemosynthetic communities with oil discoveries, upper continental slope, Gulf of Mexico

    SciTech Connect

    Sassen, R.; Brooks, J.M.; MacDonald, I.R.; Kennicutt, M.C. II; Guinasso, N.L. Jr. )

    1993-09-01

    A belt of sea-floor oil seeps and chemosynthetic communities has been mapped across the upper continental slope, offshore Louisiana, at depths ranging from 2000 to 1000 m. Visibly oil-stained sediments and thelmogenic gas hydrates have been recovered using piston cores and research submarines. Biomarker fingerprinting of seep oils suggests an origin from deeply buried Cretaceous or Jurassic source rocks characterized by marine kerogen. The abundance of seeps provides a unique opportunity to define their relationship to oil discoveries including Auger, Cooper, Jolliet, Marquette, Vancouver, Popeye, and Mars. Seeps are preferentially distributed over shallow salt ridges that rim intrasalt basin cooking pots, over salt diapirs, and along shallow fault traces near discoveries. Diagnostic seep-related features on the sea floor include gas hydrate mounds and outcrops, pockmarks and craters, mud volcanoes, and carbonate buildups. Many of the 50 chemosynthetic communities including tube worms, mussels, or clams thus far documented in the gulf occur near discoveries. Recent imagery from orbital platforms, including the space shuttle, shows that natural oil slicks are common on the sea surface in this area. Additional mapping of seep distributions should contribute to better defining of the limits of the deep Gulf play fairway.

  20. Larvae from deep-sea methane seeps disperse in surface waters.

    PubMed

    Arellano, Shawn M; Van Gaest, Ahna L; Johnson, Shannon B; Vrijenhoek, Robert C; Young, Craig M

    2014-07-07

    Many species endemic to deep-sea methane seeps have broad geographical distributions, suggesting that they produce larvae with at least episodic long-distance dispersal. Cold-seep communities on both sides of the Atlantic share species or species complexes, yet larval dispersal across the Atlantic is expected to take prohibitively long at adult depths. Here, we provide direct evidence that the long-lived larvae of two cold-seep molluscs migrate hundreds of metres above the ocean floor, allowing them to take advantage of faster surface currents that may facilitate long-distance dispersal. We collected larvae of the ubiquitous seep mussel "Bathymodiolus" childressi and an associated gastropod, Bathynerita naticoidea, using remote-control plankton nets towed in the euphotic zone of the Gulf of Mexico. The timing of collections suggested that the larvae might disperse in the water column for more than a year, where they feed and grow to more than triple their original sizes. Ontogenetic vertical migration during a long larval life suggests teleplanic dispersal, a plausible explanation for the amphi-Atlantic distribution of "B." mauritanicus and the broad western Atlantic distribution of B. naticoidea. These are the first empirical data to demonstrate a biological mechanism that might explain the genetic similarities between eastern and western Atlantic seep fauna.

  1. Larvae from deep-sea methane seeps disperse in surface waters

    PubMed Central

    Arellano, Shawn M.; Van Gaest, Ahna L.; Johnson, Shannon B.; Vrijenhoek, Robert C.; Young, Craig M.

    2014-01-01

    Many species endemic to deep-sea methane seeps have broad geographical distributions, suggesting that they produce larvae with at least episodic long-distance dispersal. Cold-seep communities on both sides of the Atlantic share species or species complexes, yet larval dispersal across the Atlantic is expected to take prohibitively long at adult depths. Here, we provide direct evidence that the long-lived larvae of two cold-seep molluscs migrate hundreds of metres above the ocean floor, allowing them to take advantage of faster surface currents that may facilitate long-distance dispersal. We collected larvae of the ubiquitous seep mussel “Bathymodiolus” childressi and an associated gastropod, Bathynerita naticoidea, using remote-control plankton nets towed in the euphotic zone of the Gulf of Mexico. The timing of collections suggested that the larvae might disperse in the water column for more than a year, where they feed and grow to more than triple their original sizes. Ontogenetic vertical migration during a long larval life suggests teleplanic dispersal, a plausible explanation for the amphi-Atlantic distribution of “B.” mauritanicus and the broad western Atlantic distribution of B. naticoidea. These are the first empirical data to demonstrate a biological mechanism that might explain the genetic similarities between eastern and western Atlantic seep fauna. PMID:24827437

  2. Analysis of past recurrent methane seep activity using radiocarbon dating of Calyptogena spp. shells in the eastern Nankai subduction zone, Japan

    NASA Astrophysics Data System (ADS)

    Yagasaki, Kazuhiro; Ashi, Juichiro; Yokoyama, Yusuke; Miyairi, Yosuke; Kuramoto, Shin'ichi

    2016-04-01

    Fault activity around subduction zones have been widely studied and monitored through drilling of oceanic plates, studying piston cores, use of monitoring equipment or through visual analysis using submersible vehicles. Yet the understanding of how small scale faults near shallow regions of the seabed behave in relation to cold seep vent activity is still vague, especially determining when they were active in the past. In tectonically active margins such as the Nankai and Tokai regions off Japan, dense methane hydrate reservoirs have been identified. Cold seeps releasing methane rich hydrocarbon fluids are common here, supporting a wide variety of biological species that hold a symbiotic relationship with the chemosynthetic bacteria. In 1998 a large dead Calyptogena spp. bivalve colony (over 400m2 in size) was discovered off Tokai, Japan. It is unusual for a bivalve colony this size to mostly be dead, raising questions as to what caused their death. In this study we document the radiocarbon 14C age of these bivalve shells to attempt analysing the possible methane seep bahaviour in the past. The measured 14C age ranged in three age groups of 1396±36-1448±34, 1912±31-1938±35 and 5975±34. The 14C age of shells that were alive upon collection and the dissolved inorganic carbon (DIC) in seawater show little difference (˜100 14C age) indicating that shells are not heavily affected by the dead carbon effect from cold seeps that is of biogenic or thermogenic origin, which can make the age to become considerably older than the actual age. Thus the novel calibration model used was based on the seawater DIC collected above the Calyptogena spp. colony site (1133±31), which resulted in the dead shells to be clustered around 1900 Cal AD. This proves to be interesting as the predicted epicenter of the Ansei-Tokai earthquake (M 8.4) in 1854 is extremely close to the bibalve colony site. Using geological data obtained using visual analysis and sub-seafloor structural

  3. Prokaryotic diversity of a non-sulfide, low-salt cold spring sediment of Shawan County, China.

    PubMed

    Zeng, Jun; Yang, Hong-mei; Lou, Kai

    2010-10-01

    The prokaryotic diversity of a non-sulfide, low-salt cold spring sediment was investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. 241 bacterial clones were screened, which could be grouped into 86 ribotypes, based on restriction fragment length polymorphism (RFLP) analysis. These were divided into 11 phyla (Actinobacteria, Acidobacteria, Bacteroidetes, Chlorobi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Proteobacteria, Planctomycetes and Verrucomicrobia). Of these, Acidobacteria and Proteobacteria were the most dominant, representing 48% and 25% of the total bacteria clone library, respectively. For the archaeal clone library, 121 positive clones were screened and 22 ribotypes were determined. BLAST analysis indicated that all ribotypes were affiliated with the phylum Crenarchaeota. Phylogenetic analysis classified them into three subgroups (Groups I-III). Groups I and III, belonging to the Soil-Freshwater-subsurface group and Marine group I, respectively, were the dominant groups, representing 50% and 47% of the library, respectively. Of them, 20% of ribotypes were related to the cold-loving Crenarchaeota. These findings show that bacteria in spring sediments are more diverse than are archaea; in addition, the spring harbors a large number of novel bacterial and archaeal species and maybe exist novel lineages.

  4. Cryptic species of Archinome (Annelida: Amphinomida) from vents and seeps

    PubMed Central

    Borda, Elizabeth; Kudenov, Jerry D.; Chevaldonné, Pierre; Blake, James A.; Desbruyères, Daniel; Fabri, Marie-Claire; Hourdez, Stéphane; Pleijel, Fredrik; Shank, Timothy M.; Wilson, Nerida G.; Schulze, Anja; Rouse, Greg W.

    2013-01-01

    Since its description from the Galapagos Rift in the mid-1980s, Archinome rosacea has been recorded at hydrothermal vents in the Pacific, Atlantic and Indian Oceans. Only recently was a second species described from the Pacific Antarctic Ridge. We inferred the identities and evolutionary relationships of Archinome representatives sampled from across the hydrothermal vent range of the genus, which is now extended to cold methane seeps. Species delimitation using mitochondrial cytochrome c oxidase subunit I (COI) recovered up to six lineages, whereas concatenated datasets (COI, 16S, 28S and ITS1) supported only four or five of these as clades. Morphological approaches alone were inconclusive to verify the identities of species owing to the lack of discrete diagnostic characters. We recognize five Archinome species, with three that are new to science. The new species, designated based on molecular evidence alone, include: Archinome levinae n. sp., which occurs at both vents and seeps in the east Pacific, Archinome tethyana n. sp., which inhabits Atlantic vents and Archinome jasoni n. sp., also present in the Atlantic, and whose distribution extends to the Indian and southwest Pacific Oceans. Biogeographic connections between vents and seeps are highlighted, as are potential evolutionary links among populations from vent fields located in the east Pacific and Atlantic Oceans, and Atlantic and Indian Oceans; the latter presented for the first time. PMID:24026823

  5. Cryptic species of Archinome (Annelida: Amphinomida) from vents and seeps.

    PubMed

    Borda, Elizabeth; Kudenov, Jerry D; Chevaldonné, Pierre; Blake, James A; Desbruyères, Daniel; Fabri, Marie-Claire; Hourdez, Stéphane; Pleijel, Fredrik; Shank, Timothy M; Wilson, Nerida G; Schulze, Anja; Rouse, Greg W

    2013-11-07

    Since its description from the Galapagos Rift in the mid-1980s, Archinome rosacea has been recorded at hydrothermal vents in the Pacific, Atlantic and Indian Oceans. Only recently was a second species described from the Pacific Antarctic Ridge. We inferred the identities and evolutionary relationships of Archinome representatives sampled from across the hydrothermal vent range of the genus, which is now extended to cold methane seeps. Species delimitation using mitochondrial cytochrome c oxidase subunit I (COI) recovered up to six lineages, whereas concatenated datasets (COI, 16S, 28S and ITS1) supported only four or five of these as clades. Morphological approaches alone were inconclusive to verify the identities of species owing to the lack of discrete diagnostic characters. We recognize five Archinome species, with three that are new to science. The new species, designated based on molecular evidence alone, include: Archinome levinae n. sp., which occurs at both vents and seeps in the east Pacific, Archinome tethyana n. sp., which inhabits Atlantic vents and Archinome jasoni n. sp., also present in the Atlantic, and whose distribution extends to the Indian and southwest Pacific Oceans. Biogeographic connections between vents and seeps are highlighted, as are potential evolutionary links among populations from vent fields located in the east Pacific and Atlantic Oceans, and Atlantic and Indian Oceans; the latter presented for the first time.

  6. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps.

    PubMed

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V; Marlow, Jeffrey J; Orphan, Victoria J

    2014-10-07

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with (13)C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate-methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling.

  7. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

    PubMed Central

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; Marlow, Jeffrey J.; Orphan, Victoria J.

    2014-01-01

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate–methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling. PMID:25246590

  8. BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

    USGS Publications Warehouse

    Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

    2014-01-01

    BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

  9. Ecology of Two Terrestrial Serpentinizing Fluid Seeps Offers a Glimpse of the Deep Biosphere

    NASA Astrophysics Data System (ADS)

    Woycheese, K. M.; Meyer-Dombard, D. R.; Cardace, D.; Gulecal, Y.; Arcilla, C. A.

    2013-12-01

    Terrestrial serpentinizing fluid seeps provide convenient access to the deep subsurface biosphere community. Serpentinization--the hydrous alteration of ultramafics--produces hydrogen and possibly methane gas. Chemotrophic microbes utilize these compounds, and may form the base of the deep subsurface trophic web. Here, the geochemical environment of two terrestrial serpentinizing fluid seeps was characterized and community composition was determined. The first site is Yanartas in the Tekirova ophiolite complex (Turkey). Yanartas hosts gas and fluid seeps, the latter of which may be ephemeral. The second site is Manleluag Spring in the Zambales ophiolite range (the Philippines). In Manleluag, the fluid seeps result in the formation of large carbonate terraces. Illumina MiSeq sequencing of the small-subunit rDNA (universal primers) from Yanartas and Manleluag indicates distinct microbial communities, with some shared taxa. Methanogenic archaeal taxa were present in sediments collected from both seeps. The most dominant taxa were the Methanobacteria, with Manleluag sediments having a ten-fold higher abundance than Yanartas. The nitrifying archaea, Thaumarchaeota, were also found at both sites. Bacterial populations at both locations are diverse and primarily composed of heterotrophic taxa. At Yanartas, Alpha- and Betaproteobacteria taxa are dominant (~60% total), while at Manleluag these taxa are only 10-20% of the total reads. Clostridia and Bacteriodetes comprise nearly 35% of the sequence data at the source seep in Manleluag; at Yanartas these taxa make up ~10% of sequence data. Down an outflow channel at Manleluag, the population shifted to Thermales and Hydrogenophilales (~50% of sequence data). At Yanartas Alpha- and Betaproteobacterial taxa continued to dominate downstream, but in one outflow channel an orange, mineralized biofilm is evident. This pigmentation may result from the carotenoid-producing Rhodobacteraceae, which were only found in the orange

  10. Using mobile, internet connected deep sea crawlers for spatial and temporal analysis of cold seep ecosystems and the collection of real-time classroom data for extreme environment education.

    NASA Astrophysics Data System (ADS)

    Purser, Autun; Kwasnitschka, Tom; Duda, Alexander; Schwendner, Jakob; Bamberg, Marlene; Sohl, Frank; Doya, Carol; Aguzzi, Jacopo; Best, Mairi; Llovet, Neus Campanya I.; Scherwath, Martin; Thomsen, Laurenz

    2015-04-01

    Cabled internet and power connectivity with the deep sea allow instruments to operate in the deep sea at higher temporal resolutions than was possible historically, with the reliance on battery life and data storage capacities. In addition to the increase in sensor temporal frequency, cabled infrastructures now allow remote access to and control of mobile platforms on the seafloor. Jacobs University Bremen, in combination with collaborators from the Robotic Exploration of Extreme Environments (ROBEX) project, CSIC Barcelona and Ocean Networks Canada have been operating tracked deep sea crawler vehicles at ~890 m depth at the dynamic Barkley Canyon methane seep site, Pacific Canada during the last ~4 years. The vehicle has been able to explore an area of ~50 m radius, allowing repeated visits to numerous microhabitats. Mounting a range of sensors, including temperature, pressure, conductivity, fluorescence, turbidity, flow and methane concentration sensors, as well as various camera systems a large dataset has been compiled. Several methane pockmarks are present in the survey area, and geological, biological and oceanographic changes have been monitored over a range of timescales. Several publications have been produced, and in this presentation we introduce further data currently under analysis. Cabled internet connectivity further allows mobile platforms to be used directly in education. As part of the ROBEX project, researchers and students from both terrestrial and planetary sciences are using the crawler in an ongoing study project. Students are introduced to statistical methods from both fields during the course and in later stages they can plan their own research using the in-situ crawler, and follow the progress of their investigations live, then analyse the collected data using the techniques introduced during the course. Cabled infrastructures offer a unique facility for spatial investigation of extreme ecosystems over time, and for the 'hands on

  11. The I.A.G. / A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) Programme: Current and future activities

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Lamoureux, Scott; Decaulne, Armelle

    2013-04-01

    Projected climate change in cold regions is expected to alter melt season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. Similarly, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. These effects will undoubtedly change surface environments in cold regions and alter the fluxes of sediments, nutrients and solutes, but the absence of quantitative data and coordinated geomorphic process monitoring and analysis to understand the sensitivity of the Earth surface environment is acute in cold climate environments. The International Association of Geomorphologists (I.A.G. / A.I.G. ) SEDIBUD (Sediment Budgets in Cold Environments) Programme was formed in 2005 to address this existing key knowledge gap. SEDIBUD currently has about 400 members worldwide and the Steering Committee of this international programme is composed of ten scientists from eight different countries: Achim A. Beylich (Chair) (Norway), Armelle Decaulne (Secretary) (France), John C. Dixon (USA), Scott F. Lamoureux (Vice-Chair) (Canada), John F. Orwin (Canada), Jan-Christoph Otto (Austria), Irina Overeem (USA), Thorsteinn Sæmundsson (Iceland), Jeff Warburton (UK) and Zbigniew Zwolinski (Poland). The central research question of this global group of scientists is to: Assess and model the contemporary sedimentary fluxes in cold climates, with emphasis on both particulate and dissolved components. Initially formed as European Science Foundation (ESF) Network SEDIFLUX (Sedimentary Source-to-Sink Fluxes in Cold Environments) (2004 - ), SEDIBUD has further expanded to a global group of researchers with field research sites located in polar and alpine regions in the northern and southern hemisphere. Research carried out at each of the close to 50 defined SEDIBUD key test sites varies by programme, logistics and available

  12. Methane and sulfur cycling in terrestrial hydrocarbon seeps

    NASA Astrophysics Data System (ADS)

    Lin, L.; Wang, P.; Cheng, T.; Ling, Y.; Sun, C.; Chen, Y.; Wang, C.; Wu, J.; Chu, P.

    2009-12-01

    Hydrocarbon seeps are ubiquitous in marine and terrestrial environments where gaseous fluids with unconsolidated, fine-grained sediments ascend along fractures prior to being discharged on seafloor or land surface. Complex geological and microbial processes are involved in the sequestration of photosynthetically produced organic carbon into deep subsurface environments and cycling of methane and carbon dioxide back to atmosphere. Extensive studies conducted on marine settings indicate that geochemical stratification in sediment porewater is dynamically regulated by various microbial processes. Whether the experience accumulated over the decadal observation on marine settings could be applied to shallow and deep biosphere beneath terrestrial hydrocarbon seeps remains poorly constrained. To address the issue about how carbon and sulfur compounds were cycled in terrestrial hydrocarbon seeps, this presentation summarized the results obtained from samples collected in two sites (one at 60C and the other at 27C) of southwestern Taiwan. These sites characterized by continuously voluminous discharge of hydrocarbons were considered as the model analogs that would provide better constraints on microbial processes at ambient and high temperatures in seep-related subsurface environments. Our findings indicated that sulfate reduction and methanogenesis were active at temperatures up to 80C. Sulfate reducing and fermentative populations shifted substantially upon incubations at different temperatures, suggesting that degradation of organic carbon could only proceed with collaborative interactions among metabolisms. The proliferation of mesophilic sulfate reduction in sulfate-deprived terrestrial environments appears to be best facilitated by atmospheric oxidation of pyrite inherited in sediments. Sulfate produced in surface environments migrated downward to fuel sulfate reduction coupled to anaerobic methane oxidation near the sulfate-to-methane transition. Of various

  13. Turbidity observations in sediment flux studies: Examples from Russian rivers in cold environments

    NASA Astrophysics Data System (ADS)

    Tananaev, N. I.; Debolskiy, M. V.

    2014-08-01

    Turbidity is commonly used as a proxy to estimate suspended sediment content in streams, and for hydroecological purposes. The scope of this paper is to give an outlook to wider applications of nephelometric turbidimetry as a method. Uncalibrated turbidity records in conjunction with water chemistry data prove useful in detecting watershed reaction to single hydrological events during the spring flood in Arctic Russia. The turbidimetric survey technique was applied to study the spatial variability of sediment yield features on small rivers of the south-eastern part of Sakhalin Island. Suspended sediment concentration (SSC) vs. turbidity relation follows the geological features of the terrain and reflects the land-use intensity within the watersheds. For our Igarka key site, a logarithmic regression model was developed as an instrument of SSC calculation with turbidity data for each of the four studied watersheds. A regional regression model was developed for this site, and supplementary water optics data (filtered sample turbidity) was employed to increase the reliability of SSC calculations. Our results show that factors influencing turbidity, namely water colour and sediment grain size, have to be considered in multivariate models, to minimize errors and acquire an understanding of what kind of physical response is actually measured by nephelometry-based instruments.

  14. Shelf edge exchange processes-II SEEP2-06, R/V Endeavor cruise 186

    SciTech Connect

    Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

    1989-12-01

    The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984. Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. Hydrographic data were collected on eight of the six cruises.

  15. Desulfoconvexum algidum gen. nov., sp. nov., a psychrophilic sulfate-reducing bacterium isolated from a permanently cold marine sediment.

    PubMed

    Könneke, Martin; Kuever, Jan; Galushko, Alexander; Jørgensen, Bo Barker

    2013-03-01

    A sulfate-reducing bacterium, designated JHA1(T), was isolated from a permanently cold marine sediment sampled in an Artic fjord on the north-west coast of Svalbard. The isolate was originally enriched at 4 °C in a highly diluted liquid culture amended with hydrogen and sulfate. Strain JHA1(T) was a psychrophile, growing fastest between 14 and 16 °C and not growing above 20 °C. Fastest growth was found at neutral pH (pH 7.2-7.4) and at marine concentrations of NaCl (20-30 g l(-1)). Phylogenetic analysis of 16S rRNA gene sequences revealed that strain JHA1(T) was a member of the family Desulfobacteraceae in the Deltaproteobacteria. The isolate shared 99 % 16S rRNA gene sequence similarity with an environmental sequence obtained from permanently cold Antarctic sediment. The closest recognized relatives were Desulfobacula phenolica DSM 3384(T) and Desulfobacula toluolica DSM 7467(T) (both <95 % sequence similarity). In contrast to its closest phylogenetic relatives, strain JHA1(T) grew chemolithoautotrophically with hydrogen as an electron donor. CO dehydrogenase activity indicated the operation of the reductive acetyl-CoA pathway for inorganic carbon assimilation. Beside differences in physiology and morphology, strain JHA1(T) could be distinguished chemotaxonomically from the genus Desulfobacula by the absence of the cellular fatty acid C16 : 0 10-methyl. Phylogenetic differentiation from other genera was further supported by DsrAB and AprBA sequence analysis. Based on the described phylogenetic and phenotypic differences between strain JHA1(T) and its closest relatives, the establishment of a novel genus and a novel species, Desulfoconvexum algidum gen. nov., sp. nov. is proposed. The type strain is JHA1(T) ( = DSM 21856(T)  = JCM 16085(T)).

  16. Tectono-Stratigraphy of the Seeps on the Guaymas Basin at the Sonora Margin, Gulf of California, Mexico

    NASA Astrophysics Data System (ADS)

    Figueroa Albornoz, L. J.; Mortera-Gutierrez, C. A.; Bandy, W. L.; Escobar-Briones, E. G.; Godfroy, A.; Fouquet, Y.

    2013-05-01

    Recently several hydrothermal and gas seeps systems has been located precisely at the Sonora margin within the Guaymas Basin (GB), Gulf of California. Since late 1970's , several marine studies had reported two main hydrothermal systems in the Guaymas Rift (one at the Northern Rift, and other at the Southern Rift) and a cold seeps system at the Satellite Basin in the Sonora-margin lower edge. During the campaign BIG10, onboard the IFREMER vessel, NO L'Atalante, the EM122 echo-sounder log more than 30,000 water column acoustic images, which allows us to create a data base of the bubble plumes active systems on the northern part of the GB and the Sonora Margin. These plumes are the expression on the water column of an active seeps site during the cruise time. These images document the presence of the cold seep activity around the scarp of the Guaymas Transform Fault (GTF), and within the Satellite Basin. Few active plumes are first located off-axis, on both sides of the Northern Rift. Although it is not observed any plume within NR. Sub-bottom profiles and bathymetric data logged during the campaign GUAYRIV10, onboard the UNAM vessel, BO EL PUMA, are analyzed to determine the shallow tectonic-stratigraphy of GB near the Sonora Margin. We analyze 17 high-resolution seismic profiles (13 with NE-SW strike and 3 with NW-SE strike). From this data set, the continental shelf stratigraphy at the Sonora Margin tilts toward the slope, showing 3 low angle unconformities due to tectonics and slope angle changes. The strata slope changes angle up to 60°. However, the constant trans-tension shear along the GTF causes gravitation instability on the slope, generating a few submarine landslides close to the Northern Rift, and the rotation of blocks, tilting toward the shelf. To the north, the GTF splits in two fault escarpments, forming a narrow pull-apart basin, known as Satellite Basin. The submarine canyon from the Sonora River flows through the Satellite Basin into the GB

  17. Dimorphism in methane seep-dwelling ecotypes of the largest known bacteria

    PubMed Central

    Bailey, Jake V; Salman, Verena; Rouse, Gregory W; Schulz-Vogt, Heide N; Levin, Lisa A; Orphan, Victoria J

    2011-01-01

    We present evidence for a dimorphic life cycle in the vacuolate sulfide-oxidizing bacteria that appears to involve the attachment of a spherical Thiomargarita-like cell to the exteriors of invertebrate integuments and other benthic substrates at methane seeps. The attached cell elongates to produce a stalk-like form before budding off spherical daughter cells resembling free-living Thiomargarita that are abundant in surrounding sulfidic seep sediments. The relationship between the attached parent cell and free-living daughter cell is reminiscent of the dimorphic life modes of the prosthecate Alphaproteobacteria, but on a grand scale, with individual elongate cells reaching nearly a millimeter in length. Abundant growth of attached Thiomargarita-like bacteria on the integuments of gastropods and other seep fauna provides not only a novel ecological niche for these giant bacteria,