Forskning
I am a microbial ecologist interested in how natural and human drivers affect populations, communities and ecosystems at different spatial and temporal scales. My research is centered around the following research questions:
How is microbial community structure and diversiy shaped by chemical power supply?
What is the connection between the geological setting, geochemistry, and microbial ecology of hydrothermal systems?
How does marine mine tailings in Norwegian fjords affect microbial life?
What is the optimal microbial community structure in land-based fish farms (RAS), and how to maintain it?
To address these questions we make use of population dynamic models, field observations, and statistical analyses. A central part of our work is also bioinformatic analyses of next generation sequencing data.
Please make contact if you are interested in a PhD, MSc, or a Bachelor project connected to any of these themes.
Publikasjoner
Vitenskapelig artikkel
- Hribovšek, Petra; Denny, Emily Maria; Mall, Achim et al. (2024). daptation strategies of iron-oxidizing bacteria Gallionella and Zetaproteobacteria crossing the marine–freshwater barrier. (ekstern lenke)
- Jafari, Leila; Montjourides, Marie Aline; Hosfeld, Anne-Camilla Diesen et al. (2024). Biofilter and degasser performance at different alkalinity levels in a brackish water pilot scale recirculating aquaculture system (RAS) for post-smolt Atlantic salmon. (ekstern lenke)
- Grant, Danielle; Steinsland, Kristine; Cordier, Tristan et al. (2024). Sedimentary ancient DNA sequences reveal marine ecosystem shifts and indicator taxa for glacial-interglacial sea ice conditions. (ekstern lenke)
- Montjourides, Marie Aline; Röblitz, Susanna; Dahle, Håkon (2024). Optimizing alkalinity control in recirculating aquaculture systems (RAS): A dynamic modelling approach. (ekstern lenke)
- Tjendra, Jesslyn; Storesund, Julia Endresen; Dahle, Håkon et al. (2023). Molecular evidence of parallel evolution in a cyanophage. (ekstern lenke)
- Hribovšek, Petra; Denny, Emily Maria; Dahle, Håkon et al. (2023). Putative novel hydrogen- and iron-oxidizing sheath-producing Zetaproteobacteria thrive at the Fåvne deep-sea hydrothermal vent field. (ekstern lenke)
- Drønen, Asbjørg Karine; Roalkvam, Irene; Dahle, Håkon et al. (2022). Microbiome dataset from a marine recirculating aquaculture system (RAS) for salmon post-smolt production in Norway. (ekstern lenke)
- Drønen, Asbjørg Karine; Roalkvam, Irene; Nilsen, Hanne Katrine et al. (2022). Presence and habitats of bacterial fish pathogen relatives in a marine salmon post-smolt RAS. (ekstern lenke)
- Ramirez-Llodra, Eva; Argentino, Claudio; Baker, Maria et al. (2022). Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed. (ekstern lenke)
- Vulcano, Francesca; Hahn, Cedric Jasper; Roerdink, Desiree Lisette et al. (2022). Phylogenetic and functional diverse ANME-1 thrive in Arctic hydrothermal vents. (ekstern lenke)
- Blanc-Mathieu, Romain; Dahle, Håkon; Hofgaard, Antje et al. (2021). A persistent giant algal virus, with a unique morphology, encodes an unprecedented number of genes involved in energy metabolism. (ekstern lenke)
- Drønen, Asbjørg Karine; Roalkvam, Irene; Dahle, Håkon et al. (2021). Microbial colonization and community stability in a marine post-smolt RAS inoculated with a commercial starter culture. (ekstern lenke)
- ARSIN, Hasan; Jasilionis, Andrius; Dahle, Håkon et al. (2021). Exploring codon adjustment strategies towards Escherichia coli-based production of viral proteins encoded by HTH1, a novel prophage of the marine bacterium Hypnocyclicus thermotrophus. (ekstern lenke)
- Sandaa, Ruth-Anne; Saltvedt, Marius Rydningen; Dahle, Håkon et al. (2021). Adaptive evolution of viruses infecting marine microalgae (haptophytes), from acute infections to stable coexistence. (ekstern lenke)
- Diego Castro, David; Hannisdal, Bjarte; Dahle, Håkon (2021). On how the power supply shapes microbial survival. (ekstern lenke)
- Zhao, Rui; Dahle, Håkon; Ramírez, Gustavo A. et al. (2020). Indigenous ammonia-oxidizing archaea in oxic subseafloor oceanic crust. (ekstern lenke)
- Stokke, Runar; Reeves, Eoghan; Dahle, Håkon et al. (2020). Tailoring hydrothermal vent biodiversity towards improved biodiscovery using a novel in-situ enrichment strategy. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Dahle, Håkon et al. (2020). A case study of biofilter activation and microbial nitrification in a marine recirculation aquaculture system for rearing Atlantic salmon (Salmo salar L.). (ekstern lenke)
- Le Moine Bauer, Sven; Sjøberg, Andreas Gilje; L´Haridon, Stephane et al. (2019). Profundibacter amoris gen. nov., sp. nov., a new member of the Roseobacter clade isolated from Loki's Castle Vent Field on the Arctic Mid-Ocean Ridge. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Dahle, Håkon et al. (2019). Comparison of active biofilm carriers and commercially available inoculum for activation of biofilters in marine recirculating aquaculture systems (RAS). (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Dahle, Håkon et al. (2019). Microbial Communities in a Flow-Through Fish Farm for Lumpfish (Cyclopterus lumpus L.) During Healthy Rearing Conditions. (ekstern lenke)
- Vander Roost, Jan Pieter; Daae, Frida Lise; Steen, Ida Helene et al. (2018). Distribution patterns of iron-oxidizing Zeta- and Beta-Proteobacteria from different environmental settings of the Jan Mayen vent fields. (ekstern lenke)
- Dahle, Håkon; Le Moine Bauer, Sven; Baumberger, Tamara et al. (2018). Energy landscapes in hydrothermal chimneys shape distribution of primary producers. (ekstern lenke)
- Le Moine Bauer, Sven; Stensland, Anne; Daae, Frida Lise et al. (2018). Water masses and depth structure prokaryotic and T4-like viral communities around hydrothermal systems of the Nordic Seas. (ekstern lenke)
- Johannessen, Karen Cecilie; Vander Roost, Jan Pieter; Dahle, Håkon et al. (2017). Environmental controls on biomineralization and Fe-mound formation in a low-temperature hydrothermal system at the Jan Mayen Vent Fields. (ekstern lenke)
- Vander Roost, Jan Pieter; Thorseth, Ingunn Hindenes; Dahle, Håkon (2017). Microbial analysis of Zetaproteobacteria and co-colonizers of iron mats in the Troll Wall Vent Field, Arctic Mid-Ocean Ridge. (ekstern lenke)
- Hestetun, Jon Thomassen; Dahle, Håkon; Jørgensen, Steffen Leth et al. (2016). The Microbiome and Occurrence of Methanotrophy in Carnivorous Sponges. (ekstern lenke)
- Steen, Ida Helene; Dahle, Håkon; Stokke, Runar et al. (2016). Novel barite chimneys at the Loki´s Castle vent field shed light on key factors shaping microbial communities and functions in hydrothermal systems. (ekstern lenke)
- Le Moine Bauer, Sven; Roalkvam, Irene; Steen, Ida Helene et al. (2016). Lutibacter profundi sp. nov., isolated from a deep-sea hydrothermal system on the Arctic Mid-Ocean Ridge and emended description of the genus Lutibacter. (ekstern lenke)
- Lin, T. Jennifer; Ver Eecke, Helene C.; Breves, Elly A. et al. (2016). Linkages between mineralogy, fluid chemistry, and microbial communities within hydrothermal chimneys from the Endeavour Segment, Juan de Fuca Ridge. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Stokke, Runar et al. (2015). Physiological and genomic characterization of Arcobacter anaerophilus IR-1 reveals new metabolic features in Epsilonproteobacteria. (ekstern lenke)
- Dahle, Håkon; Økland, Ingeborg Elisabet; Thorseth, Ingunn Hindenes et al. (2015). Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge. (ekstern lenke)
- Nesbø, Camilla Lothe; Swithers, Kirsten S.; Dahle, Håkon et al. (2015). Evidence for extensive gene flow and Thermotoga subpopulations in subsurface and marine environments. (ekstern lenke)
- Stokke, Runar; Dahle, Håkon; Roalkvam, Irene et al. (2015). Functional interactions among filamentous Epsilonproteobacteria and Bacteroidetes in a deep-sea hydrothermal vent biofilm. (ekstern lenke)
- Dahle, Håkon; Roalkvam, Irene; Pedersen, Rolf B. et al. (2013). The versatile in situ gene expression of an Epsilonproteobacteria-dominated biofilm from a hydrothermal chimney. (ekstern lenke)
- Økland, Ingeborg Elisabet; Huang, Shanshan; Dahle, Håkon et al. (2012). Low temperature alteration of serpentinized ultramafic rock and implications for microbial life. (ekstern lenke)
- Roalkvam, Irene; Dahle, Håkon; Chen, Yifeng et al. (2012). Fine-scale community structure analysis of ANME in Nyegga sediments with high and low methane flux. (ekstern lenke)
- Dahle, Håkon; Hannisdal, Bjarte; Steinsbu, Bjørn Olav et al. (2011). Evolution of temperature optimum in Thermotogaceae and the prediction of trait values of uncultured organisms. (ekstern lenke)
- Roalkvam, Irene; Jørgensen, Steffen Leth; Chen, Yifeng et al. (2011). New insight into stratification of anaerobic methanotrophs in cold seep sediments. (ekstern lenke)
- DiPippo, Jonathan L.; Nesbø, Camilla L.; Dahle, Håkon et al. (2009). Kosmotoga olearia gen. nov., sp nov., a thermophilic, anaerobic heterotroph isolated from an oil production fluid. (ekstern lenke)
- Nesbø, Camilla L.; Bapteste, Eric; Curtis, Bruce et al. (2009). The Genome of Thermosipho africanus TCF52B: Lateral Genetic Connections to the Firmicutes and Archaea. (ekstern lenke)
- Dahle, Håkon; Garshol, Frøydis Kristi; Madsen, Marit Steine et al. (2008). Microbial community structure analysis of produced water from a high-temperature North Sea oil-field. (ekstern lenke)
- Lu, Ming; Grøv, Eivind; Dahle, Håkon et al. (2008). Rock support design for special lighting caverns in high in-situ stress rock mass. (ekstern lenke)
- Dahle, Håkon; Birkeland, Nils-Kåre (2006). Thermovirga lienii gen. nov., sp. nov., a novel moderately thermophilic, anaerobic, amino-acid-degrading bacterium isolated from a North Sea oil well. (ekstern lenke)
Vitenskapelig foredrag
- Fredriksen, Simen; Fernandes, Paulo; Khadka, Sujan et al. (2024). Impact of particle load on water quality and microbiota in salmon recirculating aquaculture systems. (ekstern lenke)
- Saltvedt, Marius Rydningen; Wang, Haina; Dahle, Håkon et al. (2023). PERSISTENT VIRUS PRODUCTION BY PHYTOPLANKTON. (ekstern lenke)
- Hribovšek, Petra; Denny, Emily Maria; Dahle, Håkon et al. (2022). Iron oxidizing bacteria producing sheath structures in mats on high temperature chimneys at Fåvne hydrothermal vent field. (ekstern lenke)
- Wang, Haina; Saltvedt, Marius Rydningen; Blanc-Mathieu, Romain et al. (2022). Genomes of two giant viruses and their capacity in the infection cycles. (ekstern lenke)
- Olsen, Linn Merethe Brekke; Kutti, Tina; Dahle, Håkon et al. (2019). Biogeochemical processes in submarine mine tailings and the impact on benthic fauna.. (ekstern lenke)
- Sandaa, Ruth-Anne; Blanc-Mathieu, Romain; Dahle, Håkon et al. (2019). Friends or foes, strategies for stable co-existance in algel viruses infecting haptophytes. (ekstern lenke)
- Drønen, Karine; Roalkvam, Irene; Nilsen, Hanne Katrine et al. (2018). Monitoring the main changes in the bacterial community in a RAS biofilter during the first year of operation.. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Wergeland, Heidrun Inger et al. (2018). Mikrobiell overvåkning av rognkjeksanlegg -prøvetaking og analyseverktøy. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Dahle, Håkon et al. (2018). Mikrobiell overvåkning av rognkjeksanlegg ved omfattende prøvetaking og detaljert analyseverktøy. (ekstern lenke)
- Johannessen, Karen Cecilie; Vander Roost, Jan Pieter; Dahle, Håkon et al. (2016). Local environmental controls on microbial Fe(II)-oxidation in seafloor hydrothermal deposits. (ekstern lenke)
- Økland, Ingeborg Elisabet; Dahle, Håkon; Thorseth, Ingunn Hindenes et al. (2016). Weathering of sulphides at the Arctic Mid-Ocean Ridge. (ekstern lenke)
- Økland, Ingeborg Elisabet; Gravdal, Julianne K.S.; Kvassnes, Astri J.S. et al. (2016). Mobilization of heavy metals in submarine mine tailings. (ekstern lenke)
- Steen, Ida Helene; Dahle, Håkon; Roalkvam, Irene et al. (2014). Microbial communities associated with low-temperature venting barite chimneys in the Loki´s Castle black smoker field. (ekstern lenke)
- Dahle, Håkon; Økland, Ingeborg Elisabet; Thorseth, Ingunn Hindenes et al. (2014). Use of metatranscriptomics, amplicon pyrosequencing and thermodynamics to assess how microbial communities are shaped by energy availability. (ekstern lenke)
- Dahle, Håkon; Økland, Ingeborg Elisabet; Thorseth, Ingunn Hindenes et al. (2014). Energy landscapes shape microbial communities and the distribution of biosignatures in hydrothermal systems on the Arctic Mid-Ocean Ridge. (ekstern lenke)
- Steen, Ida Helene; Dahle, Håkon; Roalkvam, Irene et al. (2014). Microbial communities associated with low-temparture venting barite chimneys in the Loki´s Castle black smoker field. (ekstern lenke)
- Thorseth, Ingunn Hindenes; Eickmann, Benjamin; Steen, Ida Helene et al. (2013). Formation of barite chimneys at low-temperature hydrothermal venting: evidence for complex geobio-interactions. (ekstern lenke)
- Dahle, Håkon; Økland, Ingeborg Elisabet; Pedersen, Rolf B. et al. (2013). Thermodynamic constraints on the microbial ecology and biogeochemical cycling in deep-sea hydrothermal systems. (ekstern lenke)
- Stokke, Runar; Dahle, Håkon; Steen, Ida Helene (2012). Metagenomics of arctic hydrothermal vent biofilms. (ekstern lenke)
- Thorseth, Ingunn Hindenes; Steen, Ida Helene; Roalkvam, Irene et al. (2011). Microbial processes and biomineralisation associated with low-temperature venting and formation of barite chimneys at Loki's Castle hydrothermal field. (ekstern lenke)
- Dahle, Håkon; Roalkvam, Irene; Jørgensen, Steffen Leth et al. (2010). A variety of microbial mats cover the chimney walls of the Loki's Castle hydrothermal field. (ekstern lenke)
- Dahle, Håkon; Garshol, Frøydis; Madsen, Marit et al. (2003). Treasures in the deep biosphere of North Sea oil-wells. (ekstern lenke)
- Bjørgo, Ole Christian; Lien, Torleiv; Madsen, Marit Steine et al. (2000). Thermosipho strain TBA5, a new thermophilic anaerobic bacterium, isolated from a North Sea oil field. (ekstern lenke)
- Bjørgo, Ole Christian; Lien, Torleiv; Madsen, Marit et al. (2000). Thermosipho strain TBA5, a new thermophilic anaerobic bacterium, isolated from a North Sea oil field. (ekstern lenke)
Fagartikkel
Poster
- Hribovšek, Petra; Denny, Emily Maria; Dahle, Håkon et al. (2022). Sheath-forming Zetaproteobacteria abundant in black smoker chimney mats at the newly discovered Fåvne hydrothermal vent field. (ekstern lenke)
- Denny, Emily Maria; Mall, Achim; Hribovšek, Petra et al. (2022). Interpretation of microbial food webs from metagenomic data in deep-sea hydrothermal vents across the Arctic Mid-Ocean Ridge. (ekstern lenke)
- Hribovšek, Petra; Denny, Emily Maria; Dahle, Håkon et al. (2022). Sheath-forming Zetaproteobacteria abundant in black smoker chimney mats at the newly discovered Fåvne hydrothermal vent field. (ekstern lenke)
- Wang, Haina; Saltvedt, Marius Rydningen; Blanc-Mathieu, Romain et al. (2022). Genomes of two giant viruses and their capacity in the infection cycles. (ekstern lenke)
- Saltvedt, Marius Rydningen; Wang, Haina; Lawrence, Janice et al. (2022). Friend or enemy: The story of a frenemy relationship between a virus and its host. (ekstern lenke)
- Hribovšek, Petra; Denny, Emily Maria; Viflot, Thomas Øfstegaard et al. (2021). Iron Oxidizers and Sheath-forming Zetaproteobacteria in Biofilms of the Newly Discovered Fåvne Hydrothermal Vent Field. (ekstern lenke)
- Drønen, Karine; Roalkvam, Irene; Dahle, Håkon et al. (2019). Effect of UV water treatment on microbial community structure Studied in two different land based aquaculture systems. (ekstern lenke)
- Roalkvam, Irene; Drønen, Karine; Dahle, Håkon et al. (2019). Microbial activation of biofilters in marine RAS -based on lab experiments and field observations. (ekstern lenke)
- Vulcano, Francesca; Stokke, Runar; Dahle, Håkon et al. (2019). Identification of key-players in anaerobic alkane oxidation in the diffuse venting Barite Field at the Loki´s castle. (ekstern lenke)
- Roalkvam, Irene; Stokke, Runar; Drønen, Karine et al. (2015). Isolation, characterization and genome analysis of a nitrate reducing Arcobacter sp. isolated from injection water. (ekstern lenke)
- Steen, Ida Helene; Stokke, Runar; Wissuwa, Juliane et al. (2014). Exploring the biotechnological potential of microbial communities in the Jan Mayen Vent Fields by use of in situ incubation chambers. (ekstern lenke)
- Le Moine Bauer, Sven; Steen, Ida Helene; Sandaa, Ruth-Anne et al. (2014). Microbial community changes within a chimney wall at the basalt-hosted Jan Mayen vent field (JMVF):Modeled predictions vs. Pyrosequencing data. (ekstern lenke)
- Vander Roost, Jan Pieter; Thorseth, Ingunn Hindenes; Pedersen, Rolf B. et al. (2014). Comparison of microbial communities within iron-containing mats at different geochemical settings in the Jan Mayen vent field. (ekstern lenke)
- Gravdal, Julianne K.S.; Økland, Ingeborg Elisabet; Dahle, Håkon et al. (2013). Stability of heavy metals in submarine tailings: A geochemical and microbiological study. (ekstern lenke)
- Steen, Ida Helene; Julianne, Wissuwa; Steinsbu, Bjørn Olav et al. (2013). Exploring the biotechnological potential of microbial communities in the Jan Mayen Vent Fields by use of in situ incubation chambers. (ekstern lenke)
- Dahle, Håkon; Roalkvam, Irene; Thorseth, Ingunn Hindenes et al. (2012). Metatranscriptomic and phylogenetic analysis of bacterial mats growing on chimney surfaces at the Loki´s Castle hydrothermal field. (ekstern lenke)
- Økland, Ingeborg Elisabet; Daae, F.L; Dahle, Håkon et al. (2012). Low temperature alteration of ultramafic rock sustaining associated microbial communities. (ekstern lenke)
- Thorseth, Ingunn Hindenes; Steen, Ida Helene; Eickmann, Benjamin et al. (2012). Microbial mediated formation of low-temperature hydrothermal barite chimneys. (ekstern lenke)
- Møller, Kirsten; Schoenberg, R; Thorseth, Ingunn Hindenes et al. (2012). Combined spectroscopic, microscopic and DNA analyses of hydrothermal siliceous Fe despots. (ekstern lenke)
- Dahle, Håkon; Roalkvam, Irene; Jørgensen, Steffen Leth et al. (2010). Microbial community structure of biomats and chimney walls of the Loki’s Castle hydrothermal field at 73°N. (ekstern lenke)
- Hoem, Solveig; Dahle, Håkon; Roalkvam, Irene et al. (2010). Detection of methanotrophic archaea in a barite chimney at Loki’s Castle, the Arctic Mid-Ocean Ridge. (ekstern lenke)
- DiPippo, Jonathan L.; Nesbø, Camilla L.; Dahle, Håkon et al. (2008). Kosmotoga olearia gen. nov., sp. nov., a thermophilic, anaerobic heterotroph isolated from Troll B oil production fluid in the North Sea. (ekstern lenke)
- Dahle, Håkon; Garshol, Frøydis; Madsen, Marit Steine et al. (2007). Microbial community structure analysis of produced water from a high-temperature oil-field in the North-Sea. (ekstern lenke)
- Dahle, Håkon; Garshol, Frøydis; Madsen, Marit Steine et al. (2007). Microbial community structure analysis of produced water from a high-temperature North-Sea oil-field. (ekstern lenke)
- Birkeland, Nils-Kåre; Dahle, Håkon; Madsen, Marit (2005). Molecular and Culture-Based Analyses of Bacteria and Archaea from a North Sea Oil-Reservoir. (ekstern lenke)
- Dahle, Håkon; Madsen, Marit Steine; Garshol, Frøydis et al. (2005). Molecular and Culture-Based Analysis of Bacteria and Archaea from a North Sea Oil-Reservoir. (ekstern lenke)
- Dahle, Håkon; Birkeland, Nils-Kåre (2004). Enrichment and isolation of thermophilic organisms capable of fermenting organic polymers. (ekstern lenke)
- Garshol, Frøydis; Dahle, Håkon; Madsen, Marit et al. (2003). Analysis of microbial communities associated with deep North Sea oil-wells using culture-dependent and culture-independent strategies. (ekstern lenke)
- Dahle, Håkon; Birkeland, Nils-Kåre (2003). Bioprospecting of thermophilic hydrogen-producing microorganisms. (ekstern lenke)
- Garshol, Frøydis; Dahle, Håkon; Madsen, Marit et al. (2003). Analysis of microbial communities associated with deep North Sea oil-wells using culture-dependent and culture-independent strategies. (ekstern lenke)
- Birkeland, Nils-Kåre; Garshol, Frøydis; Dahle, Håkon et al. (2002). Novel bacterial lineages dominating in oil-well formation water. (ekstern lenke)
- Dahle, Håkon; Lien, Torleiv; Madsen, Marit et al. (2000). Characterisation of a new bacterial strain from the order Thermotogales, isolated from an oil-producing well in the North Sea. (ekstern lenke)
- Dahle, Håkon; Lien, Torleiv; Madsen, Marit Steine et al. (2000). Characterisation of a new bacterial strain from the order Thermotogales, isolated from an oil-producing well in the North Sea. (ekstern lenke)
- Bjørgo, Ole Christian; Dahle, Håkon; Lien, Torleiv et al. (1999). Isolation and characterization of two <I>Petrotoga</I>-like isolates from a North Sea oil-producing well. (ekstern lenke)
Vitenskapelig oversiktsartikkel/review
- Aevarsson, Arnthór; Kaczorowska, Anna-Karina; Adalsteinsson, Björn Thor et al. (2021). Going to extremes - A metagenomic journey into the dark matter of life. (ekstern lenke)
- Daae, Frida Lise; Økland, Ingeborg Elisabet; Dahle, Håkon et al. (2013). Microbial life associated with low-temperature alteration of ultramafic rocks in the Leka ophiolite complex. (ekstern lenke)
Faglig foredrag
- Saltvedt, Marius Rydningen; Lawrence, Janice; Wang, Haina et al. (2021). Vital and all over the place – A neglected group of frenemy viruses. (ekstern lenke)
- Stokke, Runar; Dahle, Håkon; Roalkvam, Irene et al. (2014). Metagenomic study of a filamentous microbial mat from the Loki´s Castle Vent Field. (ekstern lenke)
- Dahle, Håkon; Økland, Ingeborg Elisabet; Roalkvam, Irene et al. (2014). Towards a framework for analyses of how energy landscapes shape microbial communities in deep-sea hydrothermal systems. (ekstern lenke)