R. B. Pedersen

University of Bergen, Bergen, Hordaland, Norway

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Publications (141)

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    F L Daae · I Okland · H Dahle · [...] · R B Pedersen
    Full-text Dataset · Jul 2016
  • Tamara Baumberger · Gretchen L. Früh-Green · Ingunn H. Thorseth · [...] · Rolf B. Pedersen
    [Show abstract] [Hide abstract] ABSTRACT: The hydrothermal vent field Lokís Castle is located in the Mohns-Knipovich bend (73°N) of the ultraslow spreading Arctic Mid-Ocean Ridge (AMOR) close to the Bear Island sediment fan. The hydrothermal field is venting up to 320° C hot black smoker fluids near the summit of an axial volcanic ridge. Even though the active chimneys have grown on a basaltic ridge, geochemical fluid data show a strong sedimentary influence into the hydrothermal circulation at Lokís Castle. Compelling evidence for a sediment input is given by high alkalinity, high concentrations of NH4+, H2, CH4, C2+ hydrocarbons as well as low Mn and Fe contents. The low δ13C values of CO2 and CH4 and the thermogenic isotopic pattern of the C2+ hydrocarbons in the high-temperature vent fluids clearly point to thermal degradation of sedimentary organic matter and illustrate diminution of the natural carbon sequestration in sediments by hydrothermal circulation. Thus, carbon-release to the hydrosphere in Arctic regions is especially relevant in areas where the active Arctic Mid-Ocean Ridge system is in contact with the organic matter rich detrital sediment fans.
    Article · May 2016 · Geochimica et Cosmochimica Acta
  • Anders Schouw · Runar Stokke · Gunhild Bødtker · [...] · Rolf Birger Pedersen
    [Show abstract] [Hide abstract] ABSTRACT: A strictly anaerobic, mesophilic, syntrophic alkane-degrading strain, L81T, was isolated from a bacterial mat sampled from a black smoker chimney at the Loki´s Castle Vent Field. Cells were straight, rod-shaped, Gram-positive staining and motile. Growth was observed in the range of pH 6.2-9.5, 14-42 °C and 0.5-6% (w/w) NaCl, with optima at pH 7.0-8.2, 37 °C, and 3% (w/w) NaCl, respectively. Proteinous substrates, sugars, organic acids and hydrocarbons were utilized for growth. Thiosulfate was used as an external electron acceptor during growth on crude oil. Strain L81T was capable of syntrophic hydrocarbon degradation when co-cultured with a methanogenic archaeon, designated strain LG6, isolated from the same enrichment. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain L81T is affiliated with the family Lachnospiraceae, and is most closely related to Natranaerovirgae pectinivora (92% sequence similarity), and Natranaerovirgae hydrolytica (90% sequence similarity). The major cellular fatty acids of strain L81T were C15:0, anteiso-C15:0, and C16:0, and the profile was distinct from those of the Natranaerovirgae species. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, 3 unidentified phospholipids, 4 unidentified glycolipids and 2 unidentified phosphoglycolipids. The G+C content of genomic DNA was determined to be 31.7 mol%. Based on phenotypic, phylogenetic and chemotaxonomic results, strain L81T is considered to represent a novel species of a novel genus of the family Lachnospiraceae. We propose the name Abyssivirga alkaniphila gen. nov., sp. nov., with the type strain L81T = DSM 29592 = JCM 30920.
    Article · Jan 2016 · International Journal of Systematic and Evolutionary Microbiology
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    [Show abstract] [Hide abstract] ABSTRACT: In order to fully understand the cycling of elements in hydrothermal systems it is critical to understand intra-field variations in geochemical and microbiological processes in both focused, high-temperature and diffuse, low-temperature areas. To reveal important causes and effects of this variation, we performed an extensive chemical and microbiological characterization of a low-temperature venting area in the Loki's Castle Vent Field (LCVF). This area, located at the flank of the large sulfide mound, is characterized by numerous chimney-like barite (BaSO4) structures (≤ 1 m high) covered with white cotton-like microbial mats. Results from geochemical analyses, microscopy (FISH, SEM), 16S rRNA gene amplicon-sequencing and metatranscriptomics were compared to results from previous analyses of biofilms growing on black smoker chimneys at LCVF. Based on our results, we constructed a conceptual model involving the geochemistry and microbiology in the LCVF. The model suggests that CH4 and H2S are important electron donors for microorganisms in both high-temperature and low-temperature areas, whereas the utilization of H2 seems restricted to high-temperature areas. This further implies that sub-seafloor processes can affect energy-landscapes, elemental cycling, and the metabolic activity of primary producers on the seafloor. In the cotton-like microbial mats on top of the active barite chimneys, a unique network of single cells of Epsilonproteobacteria interconnected by threads of extracellular polymeric substances (EPS) was seen, differing significantly from the long filamentous Sulfurovum filaments observed in biofilms on the black smokers. This network also induced nucleation of barite crystals and is suggested to play an essential role in the formation of the microbial mats and the chimneys. Furthermore, it illustrates variations in how different genera of Epsilonproteobacteria colonize and position cells in different vent fluid mixing zones within a vent field. This may be related to niche-specific physical characteristics. Altogether, the model provides a reference for future studies and illustrates the importance of systematic comparative studies of spatially closely connected niches in order to fully understand the geomicrobiology of hydrothermal systems.
    Full-text Article · Jan 2016 · Frontiers in Microbiology
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    Full-text Poster · Aug 2015
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    Aleksandre Kandilarov · Rolf Mjelde · Ernst Flueh · Rolf Birger Pedersen
    [Show abstract] [Hide abstract] ABSTRACT: In order to gain insight into the lithology and crustal evolution of the northern Jan Mayen Ridge, North Atlantic, the horizontal components of an Ocean Bottom Seismometer (OBS) dataset were analyzed with regard to Vp/Vs-modelling and seismic anisotropy. The modelling suggests that the northernmost part of the ridge consists of Icelandic type oceanic crust, bordered to the north by anomalously thick oceanic crust formed at the Mohns spreading ridge. The modelled Vp/Vs-ratios suggest variations in gabbroic composition and present-day temperatures in the area. Anisotropy analysis reveals a fast S-wave component along the Jan Mayen Ridge. This pattern of anisotropy is most readily interpreted as dikes intruded along the ridge, suggesting that the magmatism can be related to the development of a leaky transform since Early Oligocene.
    Full-text Article · Jul 2015 · Polar Science
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    [Show abstract] [Hide abstract] ABSTRACT: Little is known about how lithoautotrophic primary production is connected to microbial organotrophic consumption in hydrothermal systems. Using a multifaceted approach, we analyzed the structure and metabolic capabilities within a biofilm growing on the surface of a black smoker chimney in the Loki's Castle vent field. Imaging revealed the presence of rod-shaped Bacteroidetes growing as ectobionts on long, sheathed microbial filaments (> 100 um) affiliated with the Sulfurovum genus within Epsilonproteobacteria. The filaments were composed of a thick (> 200 nm) stable polysaccharide, representing a substantial fraction of organic carbon produced by primary production. An integrated -omics approach enabled us to assess the metabolic potential and in situ metabolism of individual taxonomic and morphological groups identified by imaging. Specifically, we provide evidence that organotrophic Bacteroidetes attach to and glide along the surface of Sulfurovum filaments utilizing organic polymers produced by the lithoautotrophic Sulfurovum. Furthermore, in situ expression of acetyl-CoA synthetase by Sulfurovum suggested the ability to assimilate acetate, indicating recycling of organic matter in the biofilm. This study expands our understanding of the lifestyles of Epsilonproteobacteria in hydrothermal vents, their metabolic properties and co-operative interactions in deep-sea hydrothermal vent food webs. This article is protected by copyright. All rights reserved.
    Full-text Article · Jul 2015 · Environmental Microbiology
  • Jiri Slama · Rolf Birger Pedersen
    [Show abstract] [Hide abstract] ABSTRACT: Cambrian to middle Ordovician schists and phyllites in southwestern Baltica, now exposed in the (par-)autochthon to Lower Allochthon nappes of the Scandinavian Caledonides in southern Norway, contain previously unrecognized far-travelled detrital zircons with ages in the intervals 0.47–0.8 and 1.85–3.2 Ga and εHf in the range −27 to +18. These ages are assigned to Timanian and Fennoscandian Shield sources respectively and contrast with the locally derived detritus with zircon ages of c. 0.9–1.8 Ga and εHf values c. −13 to +10. The far-travelled zircons provide evidence that a steady, long-haul, source-to-sink drainage system existed from the northeastern fringe of Baltica to the SW passive margin across the whole palaeocontinent (c. 2000 km) since c. 521 Ma, and that the Timanian orogen shed detritus across large distances towards both its foreland (Baltica) and hinterland (Arctica). There are several arguments against an Avalonian source for these zircons. Recycling of the detrital zircon from the Cambrian to middle Ordovician sediments is probably responsible for the presence of Cryogenian to Middle Ordovician zircon ages in younger sedimentary sequences of southwestern Baltica. The development of an ophiolitic mélange associated with Ordovician phyllites underlying the Jotun Nappe Complex seems to mark the change to an active continental margin in the middle Ordovician, heralding the Caledonian orogeny. The study demonstrates that detrital zircon-poor fine-grained (siltstone to mudstone) sediments are an extremely valuable indicator for distal sources and favourably complement zircon-rich coarser sandstone in provenance analysis.
    Article · Jun 2015 · Journal of the Geological Society
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    F. J. Barriga · R. Fonseca · S. Dias · [...] · R. Pedersen
    Full-text Dataset · Jun 2015
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    [Show abstract] [Hide abstract] ABSTRACT: With the advent of advanced deep-sea mining technology, seafloor mining is poised to begin on a global scale. For the success of any mining operation it is crucial that both the operators and regulatory bodies possess detailed information of the resource and surrounding environment during all stages of the mining process. We propose that Synthetic Aperture Sonar (SAS) is a key emerging technology that can be used by all relevant parties at only a minimal increase in cost. This technology, originally designed for military and offshore oil and gas industry applications, can be readily applied to scientific seafloor mapping. The fine resolution of this technique allows for deposit mapping of active and inactive seafloor massive sulfide deposits. By clearly distinguishing between volcanic and hydrothermal landscapes based on features finer than the resolution of conventional multibeam systems, SAS enables an entirely new level of hydrothermal deposit survey.
    Full-text Article · Apr 2015 · Journal of Ocean Technology

Publication Stats

1k Citations

Institutions

  • 2000-2015
    • University of Bergen
      • Department of Earth Science
      Bergen, Hordaland, Norway
    • Universitetet i Tromsø
      • Department of Geology
      Tromsø, Troms, Norway
  • 2003
    • Teknologisk Institutt Norway
      Kristiania (historical), Oslo, Norway