Geologic evolution of the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Denny, Alden R.; Kelley, Deborah S.; Früh-Green, Gretchen L.

2016-02-01

The Lost City Hydrothermal Field (LCHF) is a novel serpentinite-hosted vent field located on the Atlantis Massif southern wall. Results of 2 m resolution bathymetry, side scan, and video and still imagery, integrated with direct submersible observations provide the first high-resolution geologic map of the LCHF. These data form the foundation for an evolutionary model for the vent system over the past >120,000 years. The field is located on a down-dropped bench 70 m below the summit of the massif. The bench is capped by breccia and pelagic carbonate deposits underlain by variably deformed and altered serpentinite and gabbroic rocks. Hydrothermal activity is focused at the 60 m tall, 100 m across, massive carbonate edifice "Poseidon," which is venting 91°C fluid. Hydrothermal activity declines south and west of the Poseidon complex and dies off completely at distances greater than 200 m. East of Poseidon, the most recent stage of hydrothermal flow is characterized by egress of diffuse fluids from narrow fissures within a low-angle, anastomosing mylonite zone. South of the area of current hydrothermal activity, there is evidence of two discrete previously unrecognized relict fields. Active venting sites defined by carbonate-filled fissures that cut the carbonate cap rock at the summit of the massif mark the present-day northernmost extent of venting. These spatial relationships reflect multiple stages of field development, the northward migration of venting over time, and the likely development of a nascent field at the massif summit.

The Discovery of New Deep-Sea Hydrothermal Vent Communities in the Southern Ocean and Implications for Biogeography

PubMed Central

Rogers, Alex D.; Tyler, Paul A.; Connelly, Douglas P.; Copley, Jon T.; James, Rachael; Larter, Robert D.; Linse, Katrin; Mills, Rachel A.; Garabato, Alfredo Naveira; Pancost, Richard D.; Pearce, David A.; Polunin, Nicholas V. C.; German, Christopher R.; Shank, Timothy; Boersch-Supan, Philipp H.; Alker, Belinda J.; Aquilina, Alfred; Bennett, Sarah A.; Clarke, Andrew; Dinley, Robert J. J.; Graham, Alastair G. C.; Green, Darryl R. H.; Hawkes, Jeffrey A.; Hepburn, Laura; Hilario, Ana; Huvenne, Veerle A. I.; Marsh, Leigh; Ramirez-Llodra, Eva; Reid, William D. K.; Roterman, Christopher N.; Sweeting, Christopher J.; Thatje, Sven; Zwirglmaier, Katrin

2012-01-01

Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than previously recognised. PMID:22235194

Microbial community structure across fluid gradients in the Juan de Fuca Ridge hydrothermal system.

PubMed

Anderson, Rika E; Beltrán, Mónica Torres; Hallam, Steven J; Baross, John A

2013-02-01

Physical and chemical gradients are dominant factors in shaping hydrothermal vent microbial ecology, where archaeal and bacterial habitats encompass a range between hot, reduced hydrothermal fluid and cold, oxidized seawater. To determine the impact of these fluid gradients on microbial communities inhabiting these systems, we surveyed bacterial and archaeal community structure among and between hydrothermal plumes, diffuse flow fluids, and background seawater in several hydrothermal vent sites on the Juan de Fuca Ridge using 16S rRNA gene diversity screening (clone libraries and terminal restriction length polymorphisms) and quantitative polymerase chain reaction methods. Community structure was similar between hydrothermal plumes and background seawater, where a number of taxa usually associated with low-oxygen zones were observed, whereas high-temperature diffuse fluids exhibited a distinct phylogenetic profile. SUP05 and Arctic96BD-19 sulfur-oxidizing bacteria were prevalent in all three mixing regimes where they exhibited overlapping but not identical abundance patterns. Taken together, these results indicate conserved patterns of redox-driven niche partitioning between hydrothermal mixing regimes and microbial communities associated with sinking particles and oxygen-deficient waters. Moreover, the prevalence of SUP05 and Arctic96BD-19 in plume and diffuse flow fluids indicates a more cosmopolitan role for these groups in the ecology and biogeochemistry of the dark ocean. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Post-Drilling Changes in Seabed Landscape and Megabenthos in a Deep-Sea Hydrothermal System, the Iheya North Field, Okinawa Trough

PubMed Central

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, ‘artificially’ creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term. PMID:25902075

Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

PubMed

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term.

Evolutionary Strategies of Viruses, Bacteria and Archaea in Hydrothermal Vent Ecosystems Revealed through Metagenomics

PubMed Central

Anderson, Rika E.; Sogin, Mitchell L.; Baross, John A.

2014-01-01

The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems, a high proportion of which are lysogenic, must also withstand these environmental extremes. Here, we explore the evolutionary strategies of both microorganisms and viruses in hydrothermal systems through comparative analysis of a cellular and viral metagenome, collected by size fractionation of high temperature fluids from a diffuse flow hydrothermal vent. We detected a high enrichment of mobile elements and proviruses in the cellular fraction relative to microorganisms in other environments. We observed a relatively high abundance of genes related to energy metabolism as well as cofactors and vitamins in the viral fraction compared to the cellular fraction, which suggest encoding of auxiliary metabolic genes on viral genomes. Moreover, the observation of stronger purifying selection in the viral versus cellular gene pool suggests viral strategies that promote prolonged host integration. Our results demonstrate that there is great potential for hydrothermal vent viruses to integrate into hosts, facilitate horizontal gene transfer, and express or transfer genes that manipulate the hosts’ functional capabilities. PMID:25279954

Coupled cycling of Fe and organic carbon in submarine hydrothermal systems: Modelling approach

NASA Astrophysics Data System (ADS)

Legendre, Louis; German, Christopher R.; Sander, Sylvia G.; Niquil, Nathalie

2014-05-01

It has been recently proposed that hydrothermal plumes may be a significant source of dissolved Fe to the oceans. In order to assess this proposal, we investigated the fate of dissolved Fe released from hydrothermal systems to the overlying ocean using an approach that combined modelling and field values. We based our work on a consensus conceptual model developed by members of SCOR-InterRidge Working Group 135. The model was both complex enough to capture the main processes of dissolved Fe released from hydrothermal systems and chemical transformation in the hydrothermal plume, and simple enough to be parameterized with existing field data. It included the following flows: Fe, water and heat in the high temperature vent fluids, in the fluids diffusing around the vent, and in the entrained seawater in the buoyant plume; Fe precipitation in polymetallic sulphides near the vent; transport of Fe in the non-buoyant plume, and both its precipitation in particles onto the sea bottom away from the vent and dissolution into deep-sea waters. In other words, there were three Fe input flows into the buoyant hydrothermal plume (vent-fluids; entrained diffuse flow; entrained seawater) and three Fe output flows (sedimentation from the buoyant plume as polymetallic sulfides; sedimentation from the non-buoyant plume in particulate form; export to the deep ocean in dissolved or nanoparticulate form). The output flows balanced the input flows. We transformed the conceptual model into equations, and parameterized these with field data. To do so, we assumed that all hydrothermal systems, globally, can be represented by the circumstances that prevail at the EPR 9°50'N hydrothermal field, although we knew this assumption not to be accurate. We nevertheless achieved, by following this approach, two important goals, i.e. we could assemble into a coherent framework, for the first time, several discrete data sets acquired independently over decades of field work, and we could obtain model results that were consistent with recent field observations. We used our model to explore scenarios of Fe emissions and transformations under various constraints. The modelling exercises indicated that the provision of significant amounts of dissolved Fe to the oceans by hydrothermal plumes was consistent with realistic model parameters. This supported the proposition that hydrothermal systems play significant roles in the global biogeochemical Fe cycle.

Near-vent chemical processes in a hydrothermal plume: Insights from an integrated study of the Endeavour segment

NASA Astrophysics Data System (ADS)

Coogan, L. A.; Attar, A.; Mihaly, S. F.; Jeffries, M.; Pope, M.

2017-04-01

The Endeavour segment of the Juan de Fuca mid-ocean ridge is one of the best studied ridge segments and has recently been instrumented as part of Ocean Networks Canada's NEPTUNE cabled observatory. Here we investigate the interaction between high-temperature vent fluids and the overlying water column. A new tow-yo survey found that the average temperature anomaly in the neutrally buoyant plume was ˜0.043°C. The water column temperature and light attenuation anomalies correlate linearly in some areas of the plume but in other areas there is a low light attenuation anomaly relative to the temperature anomaly. This temperature excess is interpreted to reflect heat input through (particle-poor) diffuse flow. If this is correct, about half of the heat flux along the Endeavour segment comes from diffuse flow. Sediment trap and push core data show that the mass accumulation rate of the hydrothermal component of the sediments decreases rapidly with distance from the major vent fields. Large changes in the composition of the hydrothermal component of the sediments also occur with distance from the vent fields. The composition of the sediments indicates (i) sulfides precipitate early and accumulate most rapidly close to the vents with a preferential order of element removal from the plume of Cd > Ag > Cu > Co ˜ Fe; (ii) barite is deposited somewhat further from the vents. Strontium and Pb appear to be strongly incorporated in barite and/or other sulfate minerals; (iii) at most a few percent of the mass of these "insoluble" elements that is vented gets deposited within 1.5 km of the vents.

Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea hydrothermal systems.

PubMed

Winkel, Matthias; Pjevac, Petra; Kleiner, Manuel; Littmann, Sten; Meyerdierks, Anke; Amann, Rudolf; Mußmann, Marc

2014-12-01

Diffuse hydrothermal fluids often contain organic compounds such as hydrocarbons, lipids, and organic acids. Microorganisms consuming these compounds at hydrothermal sites are so far only known from cultivation-dependent studies. To identify potential heterotrophs without prior cultivation, we combined microbial community analysis with short-term incubations using (13)C-labeled acetate at two distinct hydrothermal systems. We followed cell growth and assimilation of (13)C into single cells by nanoSIMS combined with fluorescence in situ hybridization (FISH). In 55 °C-fluids from the Menez Gwen hydrothermal system/Mid-Atlantic Ridge, a novel epsilonproteobacterial group accounted for nearly all assimilation of acetate, representing the first aerobic acetate-consuming member of the Nautiliales. In contrast, Gammaproteobacteria dominated the (13) C-acetate assimilation in incubations of 37 °C-fluids from the back-arc hydrothermal system in the Manus Basin/Papua New Guinea. Here, 16S rRNA gene sequences were mostly related to mesophilic Marinobacter, reflecting the high content of seawater in these fluids. The rapid growth of microorganisms upon acetate addition suggests that acetate consumers in diffuse fluids are copiotrophic opportunists, which quickly exploit their energy sources, whenever available under the spatially and temporally highly fluctuating conditions. Our data provide first insights into the heterotrophic microbial community, catalyzing an under-investigated part of microbial carbon cycling at hydrothermal vents. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Near-Seafloor Magnetic Exploration of Submarine Hydrothermal Systems in the Kermadec Arc

NASA Astrophysics Data System (ADS)

Caratori Tontini, F.; de Ronde, C. E. J.; Tivey, M.; Kinsey, J. C.

2014-12-01

Magnetic data can provide important information about hydrothermal systems because hydrothermal alteration can drastically reduce the magnetization of the host volcanic rocks. Near-seafloor data (≤70 m altitude) are required to map hydrothermal systems in detail; Autonomous Underwater Vehicles (AUVs) are the ideal platform to provide this level of resolution. Here, we show the results of high-resolution magnetic surveys by the ABE and Sentry AUVs for selected submarine volcanoes of the Kermadec arc. 3-D magnetization models derived from the inversion of magnetic data, when combined with high resolution seafloor bathymetry derived from multibeam surveys, provide important constraints on the subseafloor geometry of hydrothermal upflow zones and the structural control on the development of seafloor hydrothermal vent sites as well as being a tool for the discovery of previously unknown hydrothermal sites. Significant differences exist between the magnetic expressions of hydrothermal sites at caldera volcanoes ("donut" pattern) and cones ("Swiss cheese" pattern), respectively. Subseafloor 3-D magnetization models also highlight structural differences between focused and diffuse vent sites.

Investigations of a novel fauna from hydrothermal vents along the Arctic Mid-Ocean Ridge (AMOR) (Invited)

NASA Astrophysics Data System (ADS)

Rapp, H.; Schander, C.; Halanych, K. M.; Levin, L. A.; Sweetman, A.; Tverberg, J.; Hoem, S.; Steen, I.; Thorseth, I. H.; Pedersen, R.

2010-12-01

The Arctic deep ocean hosts a variety of habitats ranging from fairly uniform sedimentary abyssal plains to highly variable hard bottoms on mid ocean ridges, including biodiversity hotspots like seamounts and hydrothermal vents. Deep-sea hydrothermal vents are usually associated with a highly specialized fauna, and since their discovery in 1977 more than 400 species of animals have been described. This fauna includes various animal groups of which the most conspicuous and well known are annelids, mollusks and crustaceans. The newly discovered deep sea hydrothermal vents on the Mohns-Knipovich ridge north of Iceland harbour unique biodiversity. The Jan Mayen field consists of two main areas with high-temperature white smoker venting and wide areas with low-temperature seepage, located at 5-700 m, while the deeper Loki Castle vent field at 2400 m depth consists of a large area with high temperature black smokers surrounded by a sedimentary area with more diffuse low-temperature venting and barite chimneys. The Jan Mayen sites show low abundance of specialized hydrothermal vent fauna. Single groups have a few specialized representatives but groups otherwise common in hydrothermal vent areas are absent. Slightly more than 200 macrofaunal species have been identified from this vent area, comprising mainly an assortment of bathyal species known from the surrounding area. Analysis of stable isotope data also indicates that the majority of the species present are feeding on phytodetritus and/or phytoplankton. However, the deeper Loki Castle vent field contains a much more diverse vent endemic fauna with high abundances of specialized polychaetes, gastropods and amphipods. These specializations also include symbioses with a range of chemosynthetic microorganisms. Our data show that the fauna composition is a result of high degree of local specialization with some similarities to the fauna of cold seeps along the Norwegian margin and wood-falls in the abyssal Norwegian Sea. Few species are common to both the deep and the shallow vents, but some gastropod species show a structured population difference between the sites. Our data indicate that there has been a migration of vent fauna into the Arctic Ocean from the Pacific Ocean rather than from the known vent sites further south in the Atlantic Ocean. The discovery and sampling of these new arctic vent fields provide unique data to further understand the migration of vent organisms and interactions between different deep sea chemosynthetic environments. Based on the high degree of local adaptation and specialization of fauna from the studied sites we propose the AMOR to be a new zoogeographical province for vent fauna.

Moytirra: Discovery of the first known deep-sea hydrothermal vent field on the slow-spreading Mid-Atlantic Ridge north of the Azores

NASA Astrophysics Data System (ADS)

Wheeler, A. J.; Murton, B.; Copley, J.; Lim, A.; Carlsson, J.; Collins, P.; Dorschel, B.; Green, D.; Judge, M.; Nye, V.; Benzie, J.; Antoniacomi, A.; Coughlan, M.; Morris, K.

2013-10-01

Geological, biological, morphological, and hydrochemical data are presented for the newly discovered Moytirra vent field at 45oN. This is the only high temperature hydrothermal vent known between the Azores and Iceland, in the North Atlantic and is located on a slow to ultraslow-spreading mid-ocean ridge uniquely situated on the 300 m high fault scarp of the eastern axial wall, 3.5 km from the axial volcanic ridge crest. Furthermore, the Moytirra vent field is, unusually for tectonically controlled hydrothermal vents systems, basalt hosted and perched midway up on the median valley wall and presumably heated by an off-axis magma chamber. The Moytirra vent field consists of an alignment of four sites of venting, three actively emitting "black smoke," producing a complex of chimneys and beehive diffusers. The largest chimney is 18 m tall and vigorously venting. The vent fauna described here are the only ones documented for the North Atlantic (Azores to Reykjanes Ridge) and significantly expands our knowledge of North Atlantic biodiversity. The surfaces of the vent chimneys are occupied by aggregations of gastropods (Peltospira sp.) and populations of alvinocaridid shrimp (Mirocaris sp. with Rimicaris sp. also present). Other fauna present include bythograeid crabs (Segonzacia sp.) and zoarcid fish (Pachycara sp.), but bathymodiolin mussels and actinostolid anemones were not observed in the vent field. The discovery of the Moytirra vent field therefore expands the known latitudinal distributions of several vent-endemic genera in the north Atlantic, and reveals faunal affinities with vents south of the Azores rather than north of Iceland.

The vent microbiome: patterns and drivers

NASA Astrophysics Data System (ADS)

Pachiadaki, M.

2015-12-01

Microbial processes within deep-sea hydrothermal vents affect the global biogeochemical cycles. Still, there are significant gaps in our understanding of the microbiology and the biogeochemistry of deep-sea hydrothermal systems. Vents differ in temperature, host rock composition and fluid chemistry; factors that are hypothesized to shape the distribution of the microbial communities, their metabolic capabilities and their activities. Using large-scale single cell genomics, we obtained insights into the genomic content of several linkages of a diffuse flow vent. The genomes show high metabolic versatility. Sulfur oxidation appears to be predominant but there is the potential of using a variety of e- donors and acceptors to obtain energy. To further assess the ecological importance of the vent auto- and heterotrophs, the global biogeography of the analyzed lineages will be investigated by fragment recruitment of metagenomes produced from the same site as well as other hydrothermal systems. Metatranscriptomic and metaproteomic data will be integrated to examine the expression of the predominant metabolic pathways and thus the main energy sources driving chemoautotrophic production. The comparative analysis of the key players and associated pathways among various vent sites that differ in physicochemical characteristics is anticipated to decipher the patterns and drivers of the global dispersion and the local diversification of the vent microbiome.

Microbial biofilms associated with fluid chemistry and megafaunal colonization at post-eruptive deep-sea hydrothermal vents

NASA Astrophysics Data System (ADS)

O'Brien, Charles E.; Giovannelli, Donato; Govenar, Breea; Luther, George W.; Lutz, Richard A.; Shank, Timothy M.; Vetriani, Costantino

2015-11-01

At deep-sea hydrothermal vents, reduced, super-heated hydrothermal fluids mix with cold, oxygenated seawater. This creates temperature and chemical gradients that support chemosynthetic primary production and a biomass-rich community of invertebrates. In late 2005/early 2006 an eruption occurred on the East Pacific Rise at 9°50‧N, 104°17‧W. Direct observations of the post-eruptive diffuse-flow vents indicated that the earliest colonizers were microbial biofilms. Two cruises in 2006 and 2007 allowed us to monitor and sample the early steps of ecosystem recovery. The main objective of this work was to characterize the composition of microbial biofilms in relation to the temperature and chemistry of the hydrothermal fluids and the observed patterns of megafaunal colonization. The area selected for this study had local seafloor habitats of active diffuse flow (in-flow) interrupted by adjacent habitats with no apparent expulsion of hydrothermal fluids (no-flow). The in-flow habitats were characterized by higher temperatures (1.6-25.2 °C) and H2S concentrations (up to 67.3 μM) than the no-flow habitats, and the microbial biofilms were dominated by chemosynthetic Epsilonproteobacteria. The no-flow habitats had much lower temperatures (1.2-5.2 °C) and H2S concentrations (0.3-2.9 μM), and Gammaproteobacteria dominated the biofilms. Siboglinid tubeworms colonized only in-flow habitats, while they were absent at the no-flow areas, suggesting a correlation between siboglinid tubeworm colonization, active hydrothermal flow, and the composition of chemosynthetic microbial biofilms.

Co-registered Geochemistry and Metatranscriptomics Reveal Unexpected Distributions of Microbial Activity within a Hydrothermal Vent Field

PubMed Central

Olins, Heather C.; Rogers, Daniel R.; Preston, Christina; Ussler, William; Pargett, Douglas; Jensen, Scott; Roman, Brent; Birch, James M.; Scholin, Christopher A.; Haroon, M. Fauzi; Girguis, Peter R.

2017-01-01

Despite years of research into microbial activity at diffuse flow hydrothermal vents, the extent of microbial niche diversity in these settings is not known. To better understand the relationship between microbial activity and the associated physical and geochemical conditions, we obtained co-registered metatranscriptomic and geochemical data from a variety of different fluid regimes within the ASHES vent field on the Juan de Fuca Ridge. Microbial activity in the majority of the cool and warm fluids sampled was dominated by a population of Gammaproteobacteria (likely sulfur oxidizers) that appear to thrive in a variety of chemically distinct fluids. Only the warmest, most hydrothermally-influenced flows were dominated by active populations of canonically vent-endemic Epsilonproteobacteria. These data suggest that the Gammaproteobacteria collected during this study may be generalists, capable of thriving over a broader range of geochemical conditions than the Epsilonproteobacteria. Notably, the apparent metabolic activity of the Gammaproteobacteria—particularly carbon fixation—in the seawater found between discrete fluid flows (the intra-field water) suggests that this area within the Axial caldera is a highly productive, and previously overlooked, habitat. By extension, our findings suggest that analogous, diffuse flow fields may be similarly productive and thus constitute a very important and underappreciated aspect of deep-sea biogeochemical cycling that is occurring at the global scale. PMID:28659879

Unanticipated discovery of two rare gastropod molluscs from recently located hydrothermally influenced areas in the Okinawa Trough.

PubMed

Chen, Chong; Watanabe, Hiromi Kayama; Miyazaki, Junichi; Kawagucci, Shinsuke

2017-01-01

The deep-sea hydrothermal vent is one of the most 'extreme' environments in the marine realm. Few species are capable of inhabiting such ecosystems, despite extremely high productivity there supported by microbial chemosynthesis, leading to high biomass and low species richness. Although gastropod molluscs are one of the main constituents of megafaunal communities at vent ecosystems, most species belong to several typical families (e.g., Provannidae, Peltospiridae, Lepetodrilidae) specialised and adapted to life at vents. During recent surveys of Okinawa Trough hydrothermal vent systems, two snails atypical of vent ecosystems were unexpectedly found in newly discovered hydrothermally influenced areas. Shell and radular characteristics were used to identify the gastropods morphologically. One species was a vetigastropod, the calliostomatid Tristichotrochus ikukoae (Sakurai, 1994); and the other was a caenogastropod, the muricid Abyssotrophon soyoae (Okutani, 1959). Both gastropods were previously only known from regular non-chemosynthetic deep-sea and very rare-only two definitive published records exist for T. ikukoae and three for A. soyoae . The radula formula of Tristichotrochus ikukoae is accurately reported for the first time and based on that it is returned to genus Otukaia . For both species, barcode sequences of the cytochrome c oxidase I (COI) gene were obtained and deposited for future references. These new records represent the second record of calliostomatids from vents (third from chemosynthetic ecosystems) and the third record of muricids from vents (tenth from chemosynthetic ecosystems), and extend the distribution of both species to the southwest. Neither family has been recorded at chemosynthetic ecosystems in the western Pacific. Both were from weakly diffuse flow areas not subject to high temperature venting but were nevertheless associated with typical vent-reliant taxa such as Lamellibrachia tubeworms and Bathymodiolus mussels. These new records show that these species are capable of tolerating environmental stress associated with weak hydrothermally influenced areas, despite not being vent endemic species, adding to the list of known vent/non-vent species intersections. This signifies that such weakly influenced areas may provide key habitats for them, and that such areas may play a role in the evolution of biological adaptations to 'extreme' chemosynthetic ecosystems.

Unanticipated discovery of two rare gastropod molluscs from recently located hydrothermally influenced areas in the Okinawa Trough

PubMed Central

Watanabe, Hiromi Kayama; Miyazaki, Junichi; Kawagucci, Shinsuke

2017-01-01

Background The deep-sea hydrothermal vent is one of the most ‘extreme’ environments in the marine realm. Few species are capable of inhabiting such ecosystems, despite extremely high productivity there supported by microbial chemosynthesis, leading to high biomass and low species richness. Although gastropod molluscs are one of the main constituents of megafaunal communities at vent ecosystems, most species belong to several typical families (e.g., Provannidae, Peltospiridae, Lepetodrilidae) specialised and adapted to life at vents. Methods During recent surveys of Okinawa Trough hydrothermal vent systems, two snails atypical of vent ecosystems were unexpectedly found in newly discovered hydrothermally influenced areas. Shell and radular characteristics were used to identify the gastropods morphologically. Results One species was a vetigastropod, the calliostomatid Tristichotrochus ikukoae (Sakurai, 1994); and the other was a caenogastropod, the muricid Abyssotrophon soyoae (Okutani, 1959). Both gastropods were previously only known from regular non-chemosynthetic deep-sea and very rare—only two definitive published records exist for T. ikukoae and three for A. soyoae. The radula formula of Tristichotrochus ikukoae is accurately reported for the first time and based on that it is returned to genus Otukaia. For both species, barcode sequences of the cytochrome c oxidase I (COI) gene were obtained and deposited for future references. Discussion These new records represent the second record of calliostomatids from vents (third from chemosynthetic ecosystems) and the third record of muricids from vents (tenth from chemosynthetic ecosystems), and extend the distribution of both species to the southwest. Neither family has been recorded at chemosynthetic ecosystems in the western Pacific. Both were from weakly diffuse flow areas not subject to high temperature venting but were nevertheless associated with typical vent-reliant taxa such as Lamellibrachia tubeworms and Bathymodiolus mussels. These new records show that these species are capable of tolerating environmental stress associated with weak hydrothermally influenced areas, despite not being vent endemic species, adding to the list of known vent/non-vent species intersections. This signifies that such weakly influenced areas may provide key habitats for them, and that such areas may play a role in the evolution of biological adaptations to ‘extreme’ chemosynthetic ecosystems. PMID:29209579

Early Jurassic hydrothermal vent community from the Franciscan Complex, San Rafael Mountains, California

NASA Astrophysics Data System (ADS)

Little, Crispin T. S.; Herrington, Richard J.; Haymon, Rachel M.; Danelian, Taniel

1999-02-01

The Figueroa massive sulfide deposit, located in Franciscan Complex rocks in the San Rafael Mountains of California, preserves the only known Jurassic hydrothermal vent fossils. The Figueroa fossil assemblage is specimen rich but of low diversity and comprises, in order of decreasing abundance, vestimentiferan worm tubes, the rhynchonellid brachiopod Anarhynchia cf. gabbi and a species of ?nododelphinulid gastropod. The Figueroa fossil organisms lived at a deep-water, high-temperature vent site located on a mid-ocean ridge or seamount at an equatorial latitude. The fossil vent site was then translated northwestward by the motion of the Farallon plate and was subsequently accreted to its present location. An iron-silica exhalite bed, the probable lateral equivalent of the Figueroa deposit, contains abundant filamentous microfossils with two distinct morphologies and probably represents a lower-temperature, diffuse-flow environment. The Figueroa fossil community was subject to the same environmental conditions as modern vent communities, but it is unique among modern and other fossil vent communities in having rhynchonellid brachiopods.

Hydrothermal venting and mineralization in the crater of Kick'em Jenny submarine volcano, Grenada (Lesser Antilles)

NASA Astrophysics Data System (ADS)

Carey, Steven; Olsen, Rene; Bell, Katherine L. C.; Ballard, Robert; Dondin, Frederic; Roman, Chris; Smart, Clara; Lilley, Marvin; Lupton, John; Seibel, Brad; Cornell, Winton; Moyer, Craig

2016-03-01

Kick'em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (˜70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine-grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound-like vents at a maximum temperature of 180°C. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5-35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish-yellow bacteria with the production of Fe-oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high-resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature.

Characteristics of the cultivable bacteria from sediments associated with two deep-sea hydrothermal vents in Okinawa Trough.

PubMed

Sun, Qing-lei; Wang, Ming-qing; Sun, Li

2015-12-01

In this study, different culture-dependent methods were used to examine the cultivable heterotrophic bacteria in the sediments associated with two deep-sea hydrothermal vents (named HV1 and HV2) located at Iheya Ridge and Iheya North in Okinawa Trough. The two vents differed in morphology, with HV1 exhibiting diffuse flows while HV2 being a black smoker with a chimney-like structure. A total of 213 isolates were identified by near full-length 16S rRNA gene sequence analysis. Of these isolates, 128 were from HV1 and 85 were from HV2. The bacterial community structures were, in large parts, similar between HV1 and HV2. Nevertheless, differences between HV1 and HV2 were observed in one phylum, one class, 4 orders, 10 families, and 20 genera. Bioactivity analysis revealed that 25 isolates belonging to 9 different genera exhibited extracellular protease activities, 21 isolates from 11 genera exhibited extracellular lipase activities, and 13 isolates of 8 genera displayed antimicrobial activities. This is the first observation of a large population of bacteria with extracellular bioactivities existing in deep-sea hydrothermal vents. Taken together, the results of this study provide new insights into the characteristics of the cultivable heterotrophic bacteria in deep-sea hydrothermal ecosystems.

Hydrothermal germanium over the southern East pacific rise.

PubMed

Mortlock, R A; Froelich, P N

1986-01-03

Germanium enrichment in the oceanic water column above the southern axis of the East Pacific Rise results from hydrothermal solutions emanating from hot springs along the rise crest. This plume signature provides a new oceanic tracer of reactions between seawater and sea floor basalts during hydrothermal alteration. In contrast to the sharp plumes of (3)He and manganese, the germanium plume is broad and diffuse, suggesting the existence of pervasive venting of low-temperature solutions off the ridge axis.

The NeMO Explorer Web Site: Interactive Exploration of a Recent Submarine Eruption and Hydrothermal Vents, Axial Volcano, Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Weiland, C.; Chadwick, W. W.; Embley, R. W.

2001-12-01

To help visualize the submarine volcanic landscape at NOAA's New Millennium Observatory (NeMO), we have created the NeMO Explorer web site: http://www.pmel.noaa.gov/vents/nemo/explorer.html. This web site takes visitors a mile down beneath the ocean surface to explore Axial Seamount, an active submarine volcano 300 miles off the Oregon coast. We use virtual reality to put visitors in a photorealistic 3-D model of the seafloor that lets them view hydrothermal vents and fresh lava flows as if they were really on the seafloor. At each of six virtual sites there is an animated tour and a 360o panorama in which users can view the volcanic landscape and see biological communities within a spatially accurate context. From the six sites there are hyperlinks to 50 video clips taken by a remotely operated vehicle. Each virtual site concentrates on a different topic, including the dynamics of the 1998 eruption at Axial volcano (Rumbleometer), high-temperature hydrothermal vents (CASM and ASHES), diffuse hydrothermal venting (Marker33), subsurface microbial blooms (The Pit), and the boundary between old and new lavas (Castle vent). In addition to exploring the region geographically, visitors can also explore the web site via geological concepts. The concepts gallery lets you quickly find information about mid-ocean ridges, hydrothermal vents, vent fauna, lava morphology, and more. Of particular interest is an animation of the January 1998 eruption, which shows the rapid inflation (by over 3 m) and draining of the sheet flow. For more info see Fox et al., Nature, v.412, p.727, 2001. This project was funded by NOAA's High Performance Computing and Communication (HPCC) and Vents Programs. Our goal is to present a representative portion of the vast collection of NOAA's multimedia imagery to the public in a way that is easy to use and understand. These data are particularly challenging to present because of their high data rates and low contextual information. The 3-D models create effective context and new video technology allows us to present good quality video at lower data rates. Related curriculum materials for middle- and high-school students are also available from the NeMO web site at http://www.pmel.noaa.gov/vents/nemo/education.html. >http://www.pmel.noaa.gov/vents/nemo/explorer.html

Investigating the Influence of Magmatic Volatile Input and Seawater Entrainment on Vent Deposit Morphology and Composition in Manus Basin (Back-arc) Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Tivey, M.; Bach, W.; Tivey, M.; Seewald, J.; Craddock, P.; Rouxel, O.; Yoerger, D.; Yeats, C.; McConachy, T.; Quigley, M.; Vanko, D.

2006-12-01

In August 2006, hydrothermal activity within the eastern Manus Basin north of Papua New Guinea was investigated using a combination of mapping (SeaBeam from the R/V Melville, near-bottom multi-beam sonar and magnetometer from AUV ABE and ROV Jason-2) and sampling (fluids and solids using ROV Jason-2). Objectives included identifying tectonic/geologic settings, examining interactions of seawater with felsic rocks that constitute the high silica end-member in the range of basement compositions, determining the extent of volatile magmatic inputs into these systems, and examining the evolution of hydrothermal activity through time. At the PACMANUS (Papua New Guinea Australia Canada Manus) area five previously discovered vent fields were mapped and sampled, and a new very active field, Fenway, was located south of the Satanic Mills field. The core of the Fenway field is a 40 m diameter two-tiered mound. A large black smoker complex venting boiling (356C, 172 bar) fluids forms the upper tier, with the lower tier composed of sulfide debris, massive anhydrite-sulfide deposits, and anhydrite sand. At the DESMOS Caldera hyaloclastites and extensive patches of bleached and stained substrate were mapped and sampled, as were diffuse (72C) and focused (119C) acidic fluids with a pH (25C) of 1.0; no sulfide deposits were observed in the area. At the North Su vent field within the SuSu Knolls area even lower pH fluids were sampled (see Seewald et al., this session). Hydrothermal activity includes venting of white sulfur-rich fluids through cracks and sediments, formation of native sulfur flanges, diffuse venting through spires, and black smoker activity (324C). Anhydrite cement is also present. The abundance of massive anhydrite at Fenway and presence of anhydrite cement at North Su is consistent with significant local entrainment and heating of seawater. The extremely low pH (less than 2) of some vent fluids supports previous hypotheses that fluids in this area contain significant input of magmatic volatiles (e.g., Gamo et al. 1997, Geology 25). During the cruise, 104 black, gray, and clear fluids were sampled using gas-tight and major samplers, and 198 vent sulfide deposit, 83 altered substrate, and 43 fresh lava samples were recovered. Geophysical maps and geochemical data for solids and fluids will be used to determine the styles of mixing and reaction occurring beneath the vent fields, estimate subsurface mineral deposition, and investigate the extent to which input of magmatic fluids is occurring within each system.

The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

NASA Astrophysics Data System (ADS)

Bemis, Karen G.; Silver, Deborah; Xu, Guangyu; Light, Russ; Jackson, Darrell; Jones, Christopher; Ozer, Sedat; Liu, Li

2015-11-01

Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

Molecular Diversity and Activity of Methanogens in the Subseafloor at Deep-Sea Hydrothermal Vents of the Pacific Ocean (Invited)

NASA Astrophysics Data System (ADS)

Huber, J. A.; Merkel, A.; Holden, J. F.; Lilley, M. D.; Butterfield, D. A.

2009-12-01

Methanogenesis is thought to represent one of the most ancient metabolic pathways on Earth, and methanogens may serve as important primary producers in warm crustal habitats at deep-sea hydrothermal vents. Many of these obligate chemolithoautotrophs depend solely on geochemically-derived energy and carbon sources and grow at high temperatures under strictly anaerobic conditions. A combined geochemical and microbiological approach was used to determine the distribution and molecular diversity of methanogens in low temperature diffuse vent fluids from the Endeavour Segment R2K ISS site, as well as Axial Seamount and volcanoes of the Mariana Arc. Geochemical data from hot and adjacent warm diffuse vent fluids provided chemical indicators to guide sample selection for detailed polymerase chain reaction (PCR)-based analysis of the key enzyme for methane formation, methyl-coenzyme M reductase (mcrA), as well as archaeal 16S rRNA genes. At most Endeavour vent sites, hydrogen concentrations were too low to support hydrogenotrophic methanogensis directly and only one diffuse site, Easter Island, had a positive signal for the mcrA gene. These sequences were most closely related to members of the order Methanococcales, as well as anaerobic methane oxidizers (ANME-1). The presence of ANME, which are rarely found in non-sedimented marine environments, is another line of evidence supporting the occurrence of buried sediments at Endeavour. At Axial, a number of diffuse vents have strong chemical indicators of methanogenesis. Methanogenic communities were detected at 3 sites on the southeast side of the caldera: the northern end of the 1998 lava flow, the International District, and on the pre-1987 lava flow. Time series work at Marker 113 showed that in 4 different years over the last 6 years methanogenic communities are active and abundant, suggesting a stable anaerobic, warm subseafloor habitat. Results show that members of the order Methanococcales dominate at this site, including mesophiles and hyper/thermophiles, but that some methanogens recovered from Marker 113 are surviving at low or sub-optimal hydrogen levels. Vent 9m had a community composition similar to Marker 113, dominated by Methanococcales, and Zen Gardens, also at Axial, had a population of methanogens very different from either site. The community there was composed of members of the order Methanomicrobiales, including mesophilic methanogens previously only found in terrestrial environments. Along the Mariana Arc, Shrimp City vent at NW Rota-1 had some of the highest levels of methane detected on the entire arc, and mcrA analysis indicates members of the Methanococcales were present, as well as Methanosarcinales and anaerobic methane oxidizers. An integrated comparison of organismal and geochemical diversity will be presented to link energy transfer in these diverse hydrothermal systems from mantle to microbes.

Distribution, structure and temporal variability of hydrothermal outflow at a slow-spreading hydrothermal field from seafloor image mosaics.

NASA Astrophysics Data System (ADS)

Barreyre, Thibaut; Escartin, Javier; Cannat, Mathilde; Garcia, Rafael; Science Party, Momar'08; Science Party, Bathyluck'09

2010-05-01

The Lucky Strike hydrothermal site, located South of the Azores along the Mid-Atlantic Ridge, is one of the largest and best-known active hydrothermal fields along the ridge system. This site within the MoMAR area is also the target for the installation in 2010 of a pilot deep-sea observatory with direct telemetry to land, to be part of the European Seafloor Observatory Network (ESONET). The Lucky Strike hydrothermal site has seen extensive high-resolution, near-bottom geophysical surveys in 1996 (Lustre'96), 2006 (Momareto06), 2008 (MOMAR08) and 2009 (Bathyluck09). Vertically acquired black-and-white electronic still camera images have been projected and georeferenced to obtain 3 image mosaics covering the zone of active venting, extending ~ 700x800 m2, and with full image resolution (~10 mm pixels). These data allow us to study how hydrothermal outflow is structured, including the relationships between the zones of active high-temperature venting, areas of diffuse outflow, and the geological structure (nature of the substrate, faults and fissures, sediments, etc.). Hydrothermal outflow is systematically associated with bacterial mats that are easily identified in the imagery, allowing us to study temporal variability at two different scales. Over the 13-year period we can potentially track changes in both the geometry and intensity of hydrothermal activity throughout the system; our preliminary study of the Eiffel Tower, White Castle and Mt Segur indicate that activity has been sustained in recent times, with small changes in the detailed geometry of the diffuse outflow and its intensity. At longer times scales (hundreds to 1000 years?) imagery also shows evidence of areas of venting that are no longer active, often associated with the active structures. In combination with the high-resolution bathymetry, the imagery data thus allow us to characterize the shallow structure of hydrothermal outflow at depth, the structural and volcanic control, and ultimately quantify the heat flux associates with this hydrothermal outflow. Image mosaics are also key for the installation of instrumentation required by temporal studies, and for the infrastructure of the ESONET pilot seafloor observatory. This type of survey techniques and studies can also be extended to other areas of interest, such as hydrothermal fields, cold seeps, etc.

Lithium isotopic systematics of submarine vent fluids from arc and back-arc hydrothermal systems in the western Pacific

NASA Astrophysics Data System (ADS)

Araoka, Daisuke; Nishio, Yoshiro; Gamo, Toshitaka; Yamaoka, Kyoko; Kawahata, Hodaka

2016-10-01

The Li concentration and isotopic composition (δ7Li) in submarine vent fluids are important for oceanic Li budget and potentially useful for investigating hydrothermal systems deep under the seafloor because hydrothermal vent fluids are highly enriched in Li relative to seawater. Although Li isotopic geochemistry has been studied at mid-ocean-ridge (MOR) hydrothermal sites, in arc and back-arc settings Li isotopic composition has not been systematically investigated. Here we determined the δ7Li and 87Sr/86Sr values of 11 end-member fluids from 5 arc and back-arc hydrothermal systems in the western Pacific and examined Li behavior during high-temperature water-rock interactions in different geological settings. In sediment-starved hydrothermal systems (Manus Basin, Izu-Bonin Arc, Mariana Trough, and North Fiji Basin), the Li concentrations (0.23-1.30 mmol/kg) and δ7Li values (+4.3‰ to +7.2‰) of the end-member fluids are explained mainly by dissolution-precipitation model during high-temperature seawater-rock interactions at steady state. Low Li concentrations are attributable to temperature-related apportioning of Li in rock into the fluid phase and phase separation process. Small variation in Li among MOR sites is probably caused by low-temperature alteration process by diffusive hydrothermal fluids under the seafloor. In contrast, the highest Li concentrations (3.40-5.98 mmol/kg) and lowest δ7Li values (+1.6‰ to +2.4‰) of end-member fluids from the Okinawa Trough demonstrate that the Li is predominantly derived from marine sediments. The variation of Li in sediment-hosted sites can be explained by the differences in degree of hydrothermal fluid-sediment interactions associated with the thickness of the marine sediment overlying these hydrothermal sites.

Hydrothermal Venting at Kick'Em Jenny Submarine Volcano (West Indies)

NASA Astrophysics Data System (ADS)

Carey, S.; Croff Bell, K. L.; Dondin, F. J. Y.; Roman, C.; Smart, C.; Lilley, M. D.; Lupton, J. E.; Ballard, R. D.

2014-12-01

Kick'em Jenny is a frequently-erupting, shallow submarine volcano located ~8 km off the northwest coast of Grenada in the West Indies. The last eruption took place in 2001 but did not breach the sea surface. Focused and diffuse hydrothermal venting is taking place mainly within a small (~100 x 100 m) depression within the 300 m diameter crater of the volcano at depths of about 265 meters. Near the center of the depression clear fluids are being discharged from a focused mound-like vent at a maximum temperature of 180o C with the simultaneous discharge of numerous bubble streams. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. A sulfur component likely contributes 1-4% of the gas total. Gas flux measurements on individual bubble streams ranged from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5 to 35o C above ambient occurs throughout the depression and over large areas of the main crater. These zones are extensively colonized by reddish-yellow bacterial mats with the production of loose Fe-oxyhydroxides largely as a surface coating and in some cases, as fragile spires up to several meters in height. A high-resolution photo mosaic of the crater depression was constructed using the remotely operated vehicle Hercules on cruise NA039 of the E/V Nautilus. The image revealed prominent fluid flow patterns descending the sides of the depression towards the base. We speculate that the negatively buoyant fluid flow may be the result of second boiling of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature. Increased density may also be the result of high dissolved CO2 content of the fluids, although we were not able to measure this directly. The low amount of sulphide mineralization on the crater floor suggests that deposition may be occurring mostly subsurface, in accord with models of second boiling mineralization from other hydrothermal vent systems.

Sulfur and oxygen isotope insights into sulfur cycling in shallow-sea hydrothermal vents, Milos, Greece

PubMed Central

2014-01-01

Shallow-sea (5 m depth) hydrothermal venting off Milos Island provides an ideal opportunity to target transitions between igneous abiogenic sulfide inputs and biogenic sulfide production during microbial sulfate reduction. Seafloor vent features include large (>1 m2) white patches containing hydrothermal minerals (elemental sulfur and orange/yellow patches of arsenic-sulfides) and cells of sulfur oxidizing and reducing microorganisms. Sulfide-sensitive film deployed in the vent and non-vent sediments captured strong geochemical spatial patterns that varied from advective to diffusive sulfide transport from the subsurface. Despite clear visual evidence for the close association of vent organisms and hydrothermalism, the sulfur and oxygen isotope composition of pore fluids did not permit delineation of a biotic signal separate from an abiotic signal. Hydrogen sulfide (H2S) in the free gas had uniform δ34S values (2.5 ± 0.28‰, n = 4) that were nearly identical to pore water H2S (2.7 ± 0.36‰, n = 21). In pore water sulfate, there were no paired increases in δ34SSO4 and δ18OSO4 as expected of microbial sulfate reduction. Instead, pore water δ34SSO4 values decreased (from approximately 21‰ to 17‰) as temperature increased (up to 97.4°C) across each hydrothermal feature. We interpret the inverse relationship between temperature and δ34SSO4 as a mixing process between oxic seawater and 34S-depleted hydrothermal inputs that are oxidized during seawater entrainment. An isotope mass balance model suggests secondary sulfate from sulfide oxidation provides at least 15% of the bulk sulfate pool. Coincident with this trend in δ34SSO4, the oxygen isotope composition of sulfate tended to be 18O-enriched in low pH (<5), high temperature (>75°C) pore waters. The shift toward high δ18OSO4 is consistent with equilibrium isotope exchange under acidic and high temperature conditions. The source of H2S contained in hydrothermal fluids could not be determined with the present dataset; however, the end-member δ34S value of H2S discharged to the seafloor is consistent with equilibrium isotope exchange with subsurface anhydrite veins at a temperature of ~300°C. Any biological sulfur cycling within these hydrothermal systems is masked by abiotic chemical reactions driven by mixing between low-sulfate, H2S-rich hydrothermal fluids and oxic, sulfate-rich seawater. PMID:25183951

Biogeography and ecology of the rare and abundant microbial lineages in deep-sea hydrothermal vents.

PubMed

Anderson, Rika E; Sogin, Mitchell L; Baross, John A

2015-01-01

Environmental gradients generate countless ecological niches in deep-sea hydrothermal vent systems, which foster diverse microbial communities. The majority of distinct microbial lineages in these communities occur in very low abundance. However, the ecological role and distribution of rare and abundant lineages, particularly in deep, hot subsurface environments, remain unclear. Here, we use 16S rRNA tag sequencing to describe biogeographic patterning and microbial community structure of both rare and abundant archaea and bacteria in hydrothermal vent systems. We show that while rare archaeal lineages and almost all bacterial lineages displayed geographically restricted community structuring patterns, the abundant lineages of archaeal communities displayed a much more cosmopolitan distribution. Finally, analysis of one high-volume, high-temperature fluid sample representative of the deep hot biosphere described a unique microbial community that differed from microbial populations in diffuse flow fluid or sulfide samples, yet the rare thermophilic archaeal groups showed similarities to those that occur in sulfides. These results suggest that while most archaeal and bacterial lineages in vents are rare and display a highly regional distribution, a small percentage of lineages, particularly within the archaeal domain, are successful at widespread dispersal and colonization. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hydrothermal Activity on the Mid-Cayman Rise: ROV Jason sampling and site characterization at the Von Damm and Piccard hydrothermal fields

NASA Astrophysics Data System (ADS)

German, C. R.

2012-12-01

In January 2012 our multi-national and multi-disciplinary team conducted a series of 10 ROV Jason dives to conduct first detailed and systematic sampling of the Mid Cayman Rise hydrothermal systems at the Von Damm and Piccard hydrothermal fields. At Von Damm, hydrothermal venting is focused at and around a large conical structure that is approximately 120 m in diameter and rises at least 80m from the surrounding, largely sedimented seafloor. Clear fluids emitted from multiple sites around the flanks of the mound fall in the temperature range 110-130°C and fall on a common mixing line with hotter (>200°C) clear fluids emitted from an 8m tall spire at the summit which show clear evidence of ultramafic influence. Outcrop close to the vent-site is rare and the cone itself appear to consist of clay minerals derived from highly altered host rock. The dominant fauna at the summit of Von Damm are a new species of chemosynthetic shrimp but elsewhere the site also hosts two distinct species of chemosynthetic tube worm as well as at least one species of gastropod. The adjacent Piccard site, at ~5000m depth comprises 7 distinct sulfide mounds, 3 of which are currently active: Beebe Vents, Beebe Woods and Beebe Sea. Beebe Vents consists of 5 vigorous black smoker chimneys with maximum temperatures in the range 400-403°C while at Beebe Woods a more highly colonized thicket of up to 8m tall chimneys includes predominantly beehive diffusers with rare black smokers emitting fluids up to 353°C. Beebe Sea a diffuse site emitting fluids at 38°C Tmax, is the largest of the currently active mounds and immediately abuts a tall (8m) rift that strikes NE-SW bisecting the host Axial Volcanic Ridge. The fauna at Piccard are less diverse than at Von Damm and, predominantly, comprise the same species of MCR shrimp, a distinct gastropod species and abundant anemones.

Application of AUVs in the Exploration for and Characterization of Arc Volcano Seafloor Hydrothermal Systems

NASA Astrophysics Data System (ADS)

de Ronde, C. E. J.; Walker, S. L.; Caratori Tontini, F.; Baker, E. T.; Embley, R. W.; Yoerger, D.

2014-12-01

The application of Autonomous Underwater Vehicles (AUVs) in the search for, and characterization of, seafloor hydrothermal systems associated with arc volcanoes has provided important information at a scale relevant to the study of these systems. That is, 1-2 m resolution bathymetric mapping of the seafloor, when combined with high-resolution magnetic and water column measurements, enables the discharge of hydrothermal vent fluids to be coupled with geological and structural features, and inferred upflow zones. Optimum altitude for the AUVs is ~70 m ensuring high resolution coverage of the area, maximum exposure to hydrothermal venting, and efficency of survey. The Brothers caldera and Clark cone volcanoes of the Kermadec arc have been surveyed by ABE and Sentry. At Brothers, bathymetric mapping shows complex features on the caldera walls including embayment's, ridges extending orthogonal to the walls and the location of a dominant ring fault. Water column measurements made by light scattering, temperature, ORP and pH sensors confirmed the location of the known vent fields on the NW caldera wall and atop the two cones, and discovered a new field on the West caldera wall. Evidence for diffuse discharge was also seen on the rim of the NW caldera wall; conversely, there was little evidence for discharge over an inferred ancient vent site on the SE caldera wall. Magnetic measurements show a strong correlation between the boundaries of vent fields determined by water column measurements and observed from manned submersible and towed camera surveys, and donut-shaped zones of magnetic 'lows' that are focused along ring faults. A magnetic low was also observed to cover the SE caldera site. Similar surveys over the NW edifice of Clark volcano also show a strong correlation between active hydrothermal venting and magnetic lows. Here, the survey revealed a pattern resembling Swiss cheese of magnetic lows, indicating more widespread permeability. Moreover, the magnetic survey showed evidence for a highly magnetized ring structure ~350 m below the volcano summit considered to represent a buried (by continued growth of the cone) caldera rim. Zones of magnetic lows located inside the inferred caldera that are not associated with present-day venting are consistent with an earlier stage of hydrothermal activity.

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

PubMed Central

Fitzsimmons, Jessica N.; Boyle, Edward A.; Jenkins, William J.

2014-01-01

Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on recent abyssal dFe enrichments near hydrothermal vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209–212] argues that some hydrothermal Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (<0.4 µm) measurements from the abyssal southeast and southwest Pacific Ocean, where dFe of 1.0–1.5 nmol/kg near 2,000 m depth (0.4–0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be hydrothermally derived based on its correlation with primordial 3He and dissolved Mn (dFe:3He of 0.9–2.7 × 106). Given the known sites of hydrothermal venting in these regions, this dFe must have been transported thousands of kilometers away from its vent site to reach our sampling stations. Additionally, changes in the size partitioning of the hydrothermal dFe between soluble (<0.02 µm) and colloidal (0.02–0.4 µm) phases with increasing distance from the vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02–1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that hydrothermal vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input). PMID:25349389

Investigating microbial colonization in actively forming hydrothermal deposits using thermocouple arrays

NASA Astrophysics Data System (ADS)

Tivey, M. K.; Reysenbach, A. L.; Hirsch, M.; Steinberg, J.; Flores, G. E.

2010-12-01

Investigations of microbial colonization of very young hydrothermal deposits were carried out in 2009 at hydrothermal vents in the Lau Basin (SW Pacific), and in Guaymas Basin, Gulf of California, with a test deployment at the Rainbow vent field on the Mid-Atlantic Ridge in 2008. Our method entailed razing active chimneys and placing arrays of temperature probes (8 titanium-encased probes with their tips placed within a titanium cage) over the active flow. The chimneys that grew back through each array, encasing the temperature probe tips, were recovered after 2 to 15 days, along with temperature records. Molecular phylogenetic methods are being used to reveal the members of the microbial communities that developed in each chimney of known age and thermal history. A total of 15 array deployments were made at 10 vents in 6 different vent fields. Similar morphology beehives (with porous fine-grained interiors and steep temperature gradients across the outermost more-consolidated “wall”) formed at 2 of the 3 vents in Guaymas Basin (in 2 and 5 days at one vent and 3 and 15 days at a second), and at one vent each in the Kilo Moana (in 3 days), Tahi Moana (in 2.5 days), and Tui Malila (in 3 and 8 days) vent fields in the Lau Basin. In contrast, open conduit, thin walled chimneys grew within arrays at the Mariner vent field, Lau Basin, at 3 different vents (in 3 days at one vent, in 3 and 11 days at a second vent, and in 13 days at a third vent). A lower temperature (<280C) diffuser/spire with a filamentous biofilm formed in 15 days in an array at a hydrocarbon-rich vent in the Guaymas Basin. A similar biofilm formed after 6 days within an array placed earlier at this same vent, with little mineralization. Preliminary diversity data from the 6 and 15 day Guaymas deployments show an increased diversity of bacteria with time with initial colonizers being primarily sulfur-oxidizing Epsilonproteobacteria, with members of the Aquificales and Deltaproteobacteria appearing in the 15 day deposit. In contrast, the Archaea showed very little change in diversity over time, with members of the genera Thermococcus and Methanocaldococcus present in all samples analyzed, irrespective of location and timing of sampling. This is very different from a 72-hour test array deployment done in 2008 at Rainbow vent field, where the deposited soft material was colonized only by the sulfate-reducing archaeum, Archaeoglobus. These samples (8 beehives, 4 open conduit smokers, one diffuser spire, from chimneys of known composition, plus less consolidated biofilm material) are all of known age, and fluids were collected from 7 of the 10 vents. This suite of samples will allow comparisons to data from 2003 (Page et al., 2008, Env. Micr.), study of the potential impact of fluid chemistry, mineralogy/texture, and time on microbial diversity, and testing of hypotheses about microbial colonization and succession.

Influence of Hydrodynamics on the Larval Supply to Hydrothermal Vents on the East Pacific Rise

DTIC Science & Technology

2007-06-01

field studies, this thesis first provides new morphological and genetic identifications for hydrothermal vent gastropod larvae along the northern East Pa...cific Rise. Daily and weekly variability in the supply of hydrothermal vent gastropod larvae to two hydrothermal vents, 1.6 km apart on the East...15 1.1 Thesis Organization ................................... 18 2 Morphological and molecular identification of gastropod larvae 23 2.1 Introduction

Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.

PubMed

Edmonds, H N; Michael, P J; Baker, E T; Connelly, D P; Snow, J E; Langmuir, C H; Dick, H J B; Mühe, R; German, C R; Graham, D W

2003-01-16

Submarine hydrothermal venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of hydrothermal venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such vent systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for active hydrothermal venting on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify hydrothermal plumes dispersing from at least nine to twelve discrete vent sites. Our discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.

Living with the Heat. Submarine Ring of Fire--Grades 5-6. Hydrothermal Vent Ecology.

ERIC Educational Resources Information Center

National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

This activity is designed to teach about hydrothermal vent ecology. Students are expected to describe how hydrothermal vents are formed and characterize the physical conditions at these sites, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in hydrothermal vent…

When did decapods invade hydrothermal vents? Clues from the Western Pacific and Indian Oceans.

PubMed

Yang, Jin-Shu; Lu, Bo; Chen, Dian-Fu; Yu, Yan-Qin; Yang, Fan; Nagasawa, Hiromichi; Tsuchida, Shinji; Fujiwara, Yoshihiro; Yang, Wei-Jun

2013-02-01

Hydrothermal vents are typically located in midocean ridges and back-arc basins and are usually generated by the movement of tectonic plates. Life thrives in these environments despite the extreme conditions. In addition to chemoautotrophic bacteria, decapod crustaceans are dominant in many of the hydrothermal vents discovered to date. Contrary to the hypothesis that these species are remnants of relic fauna, increasing evidence supports the notion that hydrothermal vent decapods have diversified in more recent times with previous research attributing the origin of alvinocarid shrimps to the Miocene. This study investigated seven representative decapod species from four hydrothermal vents throughout the Western Pacific and Indian Oceans. A partitioned mix-model phylogenomic analysis of mitochondrial DNA produced a consistent phylogenetic topology of these vent-endemic species. Additionally, molecular dating analysis calibrated using multiple fossils suggested that both bythograeid crabs and alvinocarid shrimps originated in the late Mesozoic and early Cenozoic. Although of limited sampling, our estimates support the extinction/repopulation hypothesis, which postulates recent diversification times for most hydrothermal vent species due to their mass extinction by global deep-water anoxic/dysoxic events during the Late Cretaceous and Early Tertiary. The continental-derived property of the West Pacific province is compatible with the possibility that vent decapods diversified from ancestors from shallow-water regions such as cold seeps. Our results move us a step closer toward understanding the evolutionary origin of hydrothermal vent species and their distribution in the Western Pacific-Indian Ocean Region.

Temporal and spatial variation in temperature experienced by macrofauna at Main Endeavour hydrothermal vent field

NASA Astrophysics Data System (ADS)

Lee, Raymond W.; Robert, Katleen; Matabos, Marjolaine; Bates, Amanda E.; Juniper, S. Kim

2015-12-01

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10-12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays ranged from 4.1 to 11.0 °C during the deployment, indicating that on an hourly timescale the temperature conditions in this tubeworm community were fairly moderate and stable. The generality of these findings and behavioral responses of vent organisms to predictable rhythmicity and non-periodic temperature shifts are areas for further investigation.

Heavy metals from Kueishantao shallow-sea hydrothermal vents, offshore northeast Taiwan

NASA Astrophysics Data System (ADS)

Chen, Xue-Gang; Lyu, Shuang-Shuang; Garbe-Schönberg, Dieter; Lebrato, Mario; Li, Xiaohu; Zhang, Hai-Yan; Zhang, Ping-Ping; Chen, Chen-Tung Arthur; Ye, Ying

2018-04-01

Shallow water hydrothermal vents are a source of heavy metals leading to their accumulation in marine organisms that manage to live under extreme environmental conditions. This is the case at Kueishantao (KST) shallow-sea vents system offshore northeast Taiwan, where the heavy metal distribution in vent fluids and ambient seawater is poorly understood. This shallow vent is an excellent natural laboratory to understand how heavy and volatile metals behave in the nearby water column and ecosystem. Here, we investigated the submarine venting of heavy metals from KST field and its impact on ambient surface seawater. The total heavy metal concentrations in the vent fluids and vertical plumes were 1-3 orders of magnitude higher than the overlying seawater values. When compared with deep-sea hydrothermal systems, the estimated KST end-member fluids exhibited much lower concentrations of transition metals (e.g., Fe and Mn) but comparable concentrations of toxic metals such as Pb and As. This may be attributed to the lower temperature of the KST reaction zone and transporting fluids. Most of the heavy metals (Fe, Mn, As, Y, and Ba) in the plumes and seawater mainly originated from hydrothermal venting, while Cd and Pb were largely contributed by external sources such as contaminated waters (anthropogenic origin). The spatial distribution of heavy metals in the surface seawater indicated that seafloor venting impacts ambient seawater. The measurable influence of KST hydrothermal activity, however, was quite localized and limited to an area of < 1 km2. The estimated annual fluxes of heavy metals emanating from the yellow KST hydrothermal vent were: 430-2600 kg Fe, 24-145 kg Mn, 5-32 kg Ba, 10-60 kg As, 0.3-1.9 kg Cd, and 2-10 kg Pb. This study provides important data on heavy metals from a shallow-sea hydrothermal field, and it helps to better understand the environmental impact of submarine shallow hydrothermal venting.

The Third Dimension of an Active Back-arc Hydrothermal System: ODP Leg 193 at PACMANUS

NASA Astrophysics Data System (ADS)

Binns, R.; Barriga, F.; Miller, D.

2001-12-01

This first sub-seafloor examination of an active hydrothermal system hosted by felsic volcanics, at a convergent margin, obtained drill core from a high-T "smoker" site (penetrated to sim200 mbsf) and a low-T site of diffuse venting (~400mbsf). We aimed to delineate the lateral and vertical variability in mineralisation and alteration patterns, so as to understand links between volcanological, structural and hydrothermal phenomena and the sources of fluids, and to establish the nature and extent of microbial activity within the system. Technological breakthroughs included deployment of a new hard-rock re-entry system, and direct comparison in a hardrock environment of structural images obtained by wireline methods and logging-while-drilling. The PACMANUS hydrothermal site, at the 1700m-deep crest of a 500m-high layered sequence of dacitic lavas, is notable for baritic massive sulfide chimneys rich in Cu, Zn, Au and Ag. Below an extensive cap 5-40m thick of fresh dacite-rhyodacite, we found unexpectedly pervasive hydrothermal alteration of vesicular and flow-banded precursors, accompanied by variably intense fracturing and anhydrite-pyrite veining. Within what appears one major hydrothermal event affecting the entire drilled sequence, there is much overprinting and repetition of distinctly allochemical argillaceous (illite-chlorite), acid-sulfate (pyrophyllite-anhydrite) and siliceous assemblages. The alteration profiles include a transition from metastable cristobalite to quartz at depth, and are similar under low-T and high-T vent sites but are vertically condensed in a manner suggesting higher thermal gradients beneath the latter. The altered rocks are surprisingly porous (average 25%). Retention of intergranular pore spaces and open vesicles at depth implies elevated hydrothermal pressures, whereas evidence from fluid inclusions and hydrothermal brecciation denotes local or sporadic phase separation. A maximum measured temperature of 313 degC measured 8 days after drilling (360 mbsf at the diffuse venting site), if indicative of thermal gradient, suggests the presence of a very shallow ( ~1.5 km below seafloor) magmatic heat source. While isotopic characteristics of anhydrite suggest an irregularly varying component of magmatic fluid, the abundance of this mineral implies a substantial role for circulating seawater within the subsurface hydrothermal system. Other than the near-ubiquitous, fine grained disseminated pyrite in altered rocks, we found little sulfide mineralisation. Pyritic vein networks and breccias are extensive in the rapidly penetrated, but poorly recovered, interval down to 120 mbsf within our "high-T end-member" hole spudded on a mound surmounted by active (280 degC) chimneys. Anhydrite and open cavities possibly dominate this interval, from which a possible example of subhalative semi-massive sulfide containing chalcopyrite and some sphalerite was recovered near 30 mbsf. At the low-T and high-T vent sites respectively, anaerobic microbes were recorded by direct counting at depths down to 99 and 78 mbsf, and in 90 degC cultivation experiments at 69-107 and 99-129 mbsf. >http://www-odp.tamu.edu/publications/prelim/193

Fluid Flow and Sound Generation at Hydrothermal Vent Fields

DTIC Science & Technology

1988-04-01

Pacific Rise The first evidence of vent sound generation came from data collected near hydrothermal vents at 21 N on the EPR where an array of ocean...associated with hydrothermal centers, one at 21 N on the East Pacific Rise (EPR) (Reidesel et al., 1982) and one on the Juan de Fuca Ridge (Bibee and Jacobson... East Pacific Rise at 210 N : the volcanic, tectonic and hydrothermal processes at

Hydrothermal Processes

NASA Astrophysics Data System (ADS)

German, C. R.; von Damm, K. L.

2003-12-01

What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater (after C. A. Stein and S. Stein, 1994). The first geochemical evidence for the existence of hydrothermal vents on the ocean floor came in the mid-1960s when investigations in the Red Sea revealed deep basins filled with hot, salty water (40-60 °C) and underlain by thick layers of metal-rich sediment (Degens and Ross, 1969). Because the Red Sea represents a young, rifting, ocean basin it was speculated that the phenomena observed there might also prevail along other young MOR spreading centers. An analysis of core-top sediments from throughout the world's oceans ( Figure 2) revealed that such metalliferous sediments did, indeed, appear to be concentrated along the newly recognized global ridge crest (Boström et al., 1969). Another early indication of hydrothermal activity came from the detection of plumes of excess 3He in the Pacific Ocean Basin (Clarke et al., 1969) - notably the >2,000 km wide section in the South Pacific ( Lupton and Craig, 1981) - because 3He present in the deep ocean could only be sourced through some form of active degassing of the Earth's interior, at the seafloor. (62K)Figure 2. Global map of the (Al+Fe+Mn):Al ratio for surficial marine sediments. Highest ratios mimic the trend of the global MOR axis (after Boström et al., 1969). One area where early heat-flow studies suggested hydrothermal activity was likely to occur was along the Galapagos Spreading Center in the eastern equatorial Pacific Ocean (Anderson and Hobart, 1976). In 1977, scientists diving at this location found hydrothermal fluids discharging chemically altered seawater from young volcanic seafloor at elevated temperatures up to 17 °C ( Edmond et al., 1979). Two years later, the first high-temperature (380±30 °C) vent fluids were found at 21° N on the East Pacific Rise (EPR) (Spiess et al., 1980) - with fluid compositions remarkably close to those predicted from the lower-temperature Galapagos findings ( Edmond et al., 1979). Since that time, hydrothermal activity has been found at more than 40 locations throughout the Pacific, North Atlantic, and Indian Oceans (e.g., Van Dover et al., 2002) with further evidence - from characteristic chemical anomalies in the ocean water column - of its occurrence in even the most remote and slowly spreading ocean basins ( Figure 3), from the polar seas of the Southern Ocean (German et al., 2000; Klinkhammer et al., 2001) to the extremes of the ice-covered Arctic ( Edmonds et al., 2003). (61K)Figure 3. Schematic map of the global ridge crest showing the major ridge sections along which active hydrothermal vents have already been found (red circles) or are known to exist from the detection of characteristic chemical signals in the overlying water column (orange circles). Full details of all known hydrothermally active sites and plume signals are maintained at the InterRidge web-site: http://triton.ori.u-tokyo.ac.jp/~intridge/wg-gdha.htm The most spectacular manifestation of seafloor hydrothermal circulation is, without doubt, the high-temperature (>400 °C) "black smokers" that expel fluids from the seafloor along all parts of the global ocean ridge crest. In addition to being visually compelling, vent fluids also exhibit important enrichments and depletions when compared to ambient seawater. Many of the dissolved chemicals released from the Earth's interior during venting precipitate upon mixing with the cold, overlying seawater, generating thick columns of black metal-sulfide and oxide mineral-rich smoke - hence the colloquial name for these vents: "black smokers" (Figure 4). In spite of their common appearance, high-temperature hydrothermal vent fluids actually exhibit a wide range of temperatures and chemical compositions, which are determined by subsurface reaction conditions. Despite their spectacular appearance, however, high-temperature vents may only represent a small fraction - perhaps as little as 10% - of the total hydrothermal heat flux close to ridge axes. A range of studies - most notably along the Juan de Fuca Ridge (JdFR) in the NE Pacific Ocean (Rona and Trivett, 1992; Schultz et al., 1992; Ginster et al., 1994) have suggested that, instead, axial hydrothermal circulation may be dominated by much lower-temperature diffuse flow exiting the seafloor at temperatures comparable to those first observed at the Galapagos vent sites in 1977. The relative importance of high- and low-temperature hydrothermal circulation to overall ocean chemistry remains a topic of active debate. (141K)Figure 4. (a) Photograph of a "black smoker" hydrothermal vent emitting hot (>400 °C) fluid at a depth of 2,834 m into the base of the oceanic water column at the Brandon vent site, southern EPR. The vent is instrumented with a recording temperature probe. (b) Diffuse flow hydrothermal fluids have temperatures that are generally <35 °C and, therefore, may host animal communities. This diffuse flow site at a depth of 2,500 m on the EPR at 9°50' N is populated by Riftia tubeworms, mussels, crabs, and other organisms. While most studies of seafloor hydrothermal systems have focused on the currently active plate boundary (˜0-1 Ma crust), pooled heat-flow data from throughout the world's ocean basins (Figure 1) indicate that convective heat loss from the oceanic lithosphere actually continues in crust from 0-65 Ma in age ( Stein et al., 1995). Indeed, most recent estimates would indicate that hydrothermal circulation through this older (1-65 Ma) section, termed "flank fluxes," may be responsible for some 70% or more of the total hydrothermal heat loss associated with spreading-plate boundaries - either in the form of warm (20-65 °C) altered seawater, or as cooler water, which is only much more subtly chemically altered ( Mottl, 2003).When considering the impact of hydrothermal circulation upon the chemical composition of the oceans and their underlying sediments, however, attention returns - for many elements - to the high-temperature "black smoker" systems. Only here do many species escape from the seafloor in high abundance. When they do, the buoyancy of the high-temperature fluids carries them hundreds of meters up into the overlying water column as they mix and eventually form nonbuoyant plumes containing a wide variety of both dissolved chemicals and freshly precipitated mineral phases. The processes active within these dispersing hydrothermal plumes play a major role in determining the net impact of hydrothermal circulation upon the oceans and marine geochemistry.

Astronomical and atmospheric impacts on deep-sea hydrothermal vent invertebrates

PubMed Central

Legendre, Pierre; Matabos, Marjolaine; Mihály, Steve; Lee, Raymond W.; Sarradin, Pierre-Marie; Arango, Claudia P.; Sarrazin, Jozée

2017-01-01

Ocean tides and winter surface storms are among the main factors driving the dynamics and spatial structure of marine coastal species, but the understanding of their impact on deep-sea and hydrothermal vent communities is still limited. Multidisciplinary deep-sea observatories offer an essential tool to study behavioural rhythms and interactions between hydrothermal community dynamics and environmental fluctuations. Here, we investigated whether species associated with a Ridgeia piscesae tubeworm vent assemblage respond to local ocean dynamics. By tracking variations in vent macrofaunal abundance at different temporal scales, we provide the first evidence that tides and winter surface storms influence the distribution patterns of mobile and non-symbiotic hydrothermal species (i.e. pycnogonids Sericosura sp. and Polynoidae polychaetes) at more than 2 km depth. Local ocean dynamics affected the mixing between hydrothermal fluid inputs and surrounding seawater, modifying the environmental conditions in vent habitats. We suggest that hydrothermal species respond to these habitat modifications by adjusting their behaviour to ensure optimal living conditions. This behaviour may reflect a specific adaptation of vent species to their highly variable habitat. PMID:28381618

Hunting for Hydrothermal Vents at the Local-Scale Using AUV's and Machine-Learning Classification in the Earth's Oceans

NASA Astrophysics Data System (ADS)

White, S. M.

2018-05-01

New AUV-based mapping technology coupled with machine-learning methods for detecting individual vents and vent fields at the local-scale raise the possibility of understanding the geologic controls on hydrothermal venting.

Environmental controls on biomineralization and Fe-mound formation in a low-temperature hydrothermal system at the Jan Mayen Vent Fields

NASA Astrophysics Data System (ADS)

Johannessen, Karen C.; Vander Roost, Jan; Dahle, Håkon; Dundas, Siv H.; Pedersen, Rolf B.; Thorseth, Ingunn H.

2017-04-01

Diffuse low-temperature hydrothermal vents on the seafloor host neutrophilic microaerophilic Fe-oxidizing bacteria that utilize the Fe(II) supplied by hydrothermal fluids and produce intricate twisted and branching extracellular stalks. The growth behavior of Fe-oxidizing bacteria in strongly opposing gradients of Fe(II) and O2 have been thoroughly investigated in laboratory settings to assess whether extracellular stalks and aligned biomineralized fabrics may serve as biosignatures of Fe-oxidizing bacteria and indications of palaeo-redox conditions in the rock record. However, the processes controlling the growth of biogenic Fe-oxyhydroxide deposits in natural, modern hydrothermal systems are still not well constrained. In this study, we aimed to establish how variations in the texture of stratified hydrothermal Fe-oxyhydroxide deposits are linked to the physicochemical conditions of the hydrothermal environment. We conducted 16S rRNA gene analyses, microscopy and geochemical analyses of laminated siliceous Fe-mounds from the Jan Mayen Vent Fields at the Arctic Mid-Ocean Ridge. Chemical analyses of low- and high-temperature hydrothermal fluids were performed to characterize the hydrothermal system in which the Fe-deposits form. Our results reveal synchronous inter-laminar variations in texture and major and trace element geochemistry. The Fe-deposits are composed of alternating porous laminae of mineralized twisted stalks and branching tubes, Mn-rich horizons with abundant detrital sediment, domal internal cavities and thin P- and REE-enriched lamina characterized by networks of ≪1 μm wide fibers. Zetaproteobacteria constitute one third of the microbial community in the surface layer of actively forming mounds, indicating that microbial Fe-oxidation is contributing to mound accretion. We suggest that Mn-oxide precipitation and detrital sediment accumulation take place during periodically low hydrothermal fluid discharge conditions. The elevated concentrations of P and REE in distinct laminae suggest Fe-cycling and accumulation of diagenetic species at depth in the deposits during hydrothermal quiescence and co-precipitation of these species with Fe-oxyhydroxides at the mound surface with reinitiated hydrothermal discharge. The origin of the low-temperature hydrothermal source fluid and the Fe-deposits are evident by low LREE/HREE ratios and negative Eu-anomalies, which clearly differ from the LREE and Eu enrichment of nearby high-temperature white smoker venting fluids. Our study demonstrates that hydrothermal fluctuations exert the primary control on the formation of laminae and the activity of Fe-oxidizing bacteria in marine hydrothermal Fe-deposits and indicates that REE-patterns may be used to distinguish high-temperature plume fallout and biomineralized low-temperature Fe-deposits in the rock record.

Physical inter-relationships between hydrothermal activity, faulting and magmatic processes at the center of a slow-spreading, magma-rich mid-ocean ridge segment: A case study of the Lucky Strike segment (MAR, 37°03'-37‧N)

NASA Astrophysics Data System (ADS)

Fontaine, F. J.; Cannat, M.; Escartin, J.; Crawford, W. C.; Singh, S. C.

2012-12-01

The modalities and efficiency of hydrothermal heat evacuation at mid-ocean ridges (25% of the global heat loss) are controlled by the lithosphere thermal and permeability structures for which we had robust constraints only for fast/intermediate spreading axis until the last past few years during which integrated geophysical, geological and geochemical studies focused on some hydrothermal sites at slow-spreading ridges. At the Lucky Strike vent field of the mid-atlantic ridge - a hydrothermal complex composed of high-temperature (maximum T=340°C), smoker-like vents and associated diffuse flow and extracting a few hundreds MW from the oceanic lithosphere - a seafloor observatory which installation started in 2005 highlights local interactions between hydrothermal, tectonic and magmatic processes. Detailed geophysical and geological investigations stress the role of the local axial fault system on localizing high- and low-temperature ventings around the faulted rim of a paleo lava lake. Microseismic studies bring constraints on the subseafloor hydrology and suggest an along-axis flow pattern, with a privileged recharge area located about a kilometer north off the active discharges. Seismic reflection studies image a central magma chamber fueling the hydrothermal sites and also reveal its along-axis depth variations likely influencing hydrothermal cell organization and flow focusing. Such linkages among hydrothermal dynamics, heat source and crustal permeability geometries usually lack quantitative constraints at mid-ocean ridges in general, and the Lucky Strike segment settings offers a unique opportunity to couple high-resolution geophysical data to hydrodynamic model. Here we develop a series of original two- and three-dimensional numerical and physical models of hydrothermal activity, tailored to this slow-spreading environment. Our results highlight physical linkages among magmatism, tectonics and crustal hydrology stressing the key role of faulting and magma chamber roof-topology in focusing fluid flow at the center of the Lucky Strike segment. They also help identifying some causes of variations in the modalities of hydrothermal heat extraction along the global ridge network.

A deep sea Hydrothermal Vent Bio-sampler for large volume in-situ filtration of hydrothermal vent fluids

NASA Technical Reports Server (NTRS)

Behar, Alberto; Matthews, Jaret; Venkateswaran, Kasthuri; Bruckner, James; Basic, Goran; So, Edmond; Rivadeneyra, Cesar

2005-01-01

This paper provides a physical description of the current system, as well as a summary of the preliminary tests conducted in 2005: a pressure chamber test, a dive test in a 30 foot dive pool, and a dive operation at a hydrothermal vent off the northern coast of Iceland.

Comparison of diffuse CO2 degassing at Miravalles and Rincón de la Vieja volcanoes (Guanacaste Province, Costa Rica)

NASA Astrophysics Data System (ADS)

Liegler, A.; Bakkar Hindeleh, H.; Deering, C. D.; Fentress, S. E.

2015-12-01

Volcanic gas emissions are a key component for monitoring volcanic activity, magmatic input of volatiles to the atmosphere and the assessment of geothermal potential in volcanic regions. Diffuse soil degassing has been shown to represent a major part of volcanic gas emissions. However, this type of gas emission has not yet been quantified in the Guanacaste province of Costa Rica; a region of the country with several large, active or dormant volcanoes. We conducted the first study of diffuse CO2 degassing at Rincón de la Vieja and Miravalles volcanoes, both located in Guanacaste. Diffuse degassing was measured using the accumulation chamber method to quantify CO2 flux in regions where hydrothermal surface features indicate anomalous activity. The total diffuse carbon dioxide flux estimated at Miravalles in two areas, together roughly 2 km2 in size, was 135 t/day and in several areas at Rincón de la Vieja a minimum of 4 t/day. Comparatively low flux values and a very local concentration (few m2) of CO2 flux were observed at the active Rincón de la Vieja volcano, compared to the dormant Miravalles volcano, where significant soil flux was found over extended areas, not only around vents. Our assessment of the origin of these differences leads to two possibilities depending on if the surface features on the two volcanoes are fed by a common hydrothermal system or two separate ones. In the former case, the different intensity of diffuse CO2 flux could indicate a different degassing behavior and stronger concentration of gas emissions at the active vent areas at Rincon de la Vieja. In the latter case, where the hydrothermal systems are not linked, the amount of CO2 degassed through the flanks of the volcanoes could indicate that different physical and chemical conditions are governing the degassing of the two systems.

Mineralogy and Geochemistry from Trollveggen Vent Field Chimneys and Metalliferous Sediments (Mohns Ridge, West Jan Mayen Fracture Zone at 71°N)

NASA Astrophysics Data System (ADS)

Dias, S.; Cruz, I.; Fonseca, R.; Barriga, F. J.; Pedersen, R.

2010-12-01

The Jan Mayen vent fields were discovered in the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. They comprise two main active areas: (1) Soria Moria and (2) Gallionella Garden & Trollveggen. The Trollveggen vent field is located at depths of 700-750 m. Venting takes place mainly through white smoker chimneys with fluid temperatures reaching up to 260-270°C. Here we present mineralogical and geochemical data from vent chimneys and metalliferous sediments collected at the Trollveggen vent field with an ROV. Cross-sections of chimneys present evident mineralogical zonation, showing acicular barite crystals in the outer parts and sulfide enrichments in the interior (Sph + Cpy +/- Py - Po). Sediments are mainly formed by vent fragments but also by minerals precipitated by diffuse fluid circulation, showing a mineral assemblage similar to that of chimneys. Microprobe analyses were obtained both in sulfates and sulphides revealing a particular sphalerite composition, characterized by low Fe (< 2%) and high total trace metal contents (up to 4%, including Cu, Ag and Au). Geochemical profiles of gravity cores collected in the area surrounding Jan Mayen were also performed in order to investigate the presence of additional hydrothermal activity in the area. Total geochemical analyses showed a slight enrichment in trace metals, such as Cu, Zn and Fe, with exception of one core that reached 85 ppm for Cu, 150 ppm for Zn and 20% for Fe. The metal enrichment in this core suggests hydrothermal activity in the neighboring area.

Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

PubMed Central

German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M. V.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J. M.; de Lépinay, B. Mercier; Nakamura, K.; Seewald, J. S.; Smith, J. L.; Sylva, S. P.; Van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

2010-01-01

Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the ∼110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at ∼5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity—all in close proximity. PMID:20660317

Simulating Electrochemistry of Hydrothermal Vents on Enceladus and Other Ocean Worlds

NASA Astrophysics Data System (ADS)

Barge, L. M.; Krause, F. C.; Jones, J. P.; Billings, K.; Sobron, P.

2017-12-01

Gradients generated in hydrothermal systems provide a significant source of free energy for chemosynthetic life, and may play a role in present-day habitability on ocean worlds such as Enceladus that are thought to host hydrothermal activity. Hydrothermal vents are similar in some ways to typical fuel cell devices: redox/pH gradients between seawater and hydrothermal fluid are analogous to the oxidant and fuel reservoirs; conductive natural mineral deposits are analogous to electrodes; and, in hydrothermal chimneys, the porous chimney wall can function as a separator or ion-exchange membrane. Electrochemistry, founded on quantitative study of redox and other chemical disequilibria as well as the chemistry of interfaces, is uniquely suited to studying these systems. We have performed electrochemical studies to better understand the catalytic potential of seafloor minerals and vent chimneys, using samples from a black smoker vent chimney as an initial demonstration. Fuel cell experiments with electrodes made from black smoker chimney material accurately simulated the redox reactions that occur in a geological setting with this particular catalyst. Similar methods with other geo-catalysts (natural or synthetic) could be utilized to test which redox reactions or metabolisms could be driven in other hydrothermal systems, including putative vent systems on other worlds.

The Mesozoic-Cenozoic igneous intrusions and related sediment-dominated hydrothermal activities in the South Yellow Sea Basin, the Western Pacific continental margin

NASA Astrophysics Data System (ADS)

Yumao, Pang; Xunhua, Zhang; Guolin, Xiao; Luning, Shang; Xingwei, Guo; Zhenhe, Wen

2018-04-01

Various igneous complexes were identified in multi-channel seismic reflection profiles from the South Yellow Sea Basin. It is not rare that magmatic intrusions in sedimentary basins cause strong thermal perturbations and hydrothermal activities. Some intrusion-related hydrothermal vent complexes have been identified and they are considered to originate from the deep sedimentary contact aureole around igneous intrusions and terminate in upper vents structures, and are linked by a vertical conduit system. The upper vent complexes are usually eye-shaped, dome-shaped, fault-related, crater-shaped or pock-shaped in seismic profiles. A schematic model was proposed to illustrate the structures of different types of hydrothermal vent complexes. A conceptual conduit model composed of an upper pipe-like part and a lower branching part was also derived. Hydrothermal vent complexes mainly developed during the Middle-Late Cretaceous, which is coeval with, or shortly after the intrusion. The back-arc basin evolution of the area which is related to the subduction of the Paleo-Pacific plate during the Mesozoic-Cenozoic may be the principal factor for voluminous igneous complexes and vent complexes in this area. It is significant to study the characteristics of igneous complexes and related hydrothermal vent complexes, which will have implications for the future study of this area.

The potential hydrothermal systems unexplored in the Southwest Indian Ocean

NASA Astrophysics Data System (ADS)

Suo, Yanhui; Li, Sanzhong; Li, Xiyao; Zhang, Zhen; Ding, Dong

2017-06-01

Deep-sea hydrothermal vents possess complex ecosystems and abundant metallic mineral deposits valuable to human being. On-axial vents along tectonic plate boundaries have achieved prominent results and obtained huge resources, while nearly 90% of the global mid-ocean ridge and the majority of the off-axial vents buried by thick oceanic sediments within plates remain as relatively undiscovered domains. Based on previous detailed investigations, hydrothermal vents have been mapped along five sections along the Southwest Indian Ridge (SWIR) with different bathymetry, spreading rates, and gravity features, two at the western end (10°-16°E Section B and 16°-25°E Section C) and three at the eastern end (49°-52°E Section D, 52°-61°E Section E and 61°-70°E Section F). Hydrothermal vents along the Sections B, C, E and F with thin oceanic crust are hosted by ultramafic rocks under tectonic-controlled magmatic-starved settings, and hydrothermal vents along the Section D are associated with exceed magmatism. Limited coverage of investigations is provided along the 35°-47°E SWIR (between Marion and Indomed fracture zones) and a lot of research has been done around the Bouvet Island, while no hydrothermal vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of hydrothermal systems along these two sections. An off-axial hydrothermal system in the southern flank of the SWIR that exhibits ultra-thin oceanic crust associated with an oceanic continental transition is postulated to exist along the 100-Ma slow-spreading isochron in the Enderby Basin. A discrete, denser enriched or less depleted mantle beneath the Antarctic Plate is an alternative explanation for the large scale thin oceanic crust concentrated on the southern flank of the SWIR.

Feeding behaviour: hydrothermal vent crabs feast on sea 'snow'.

PubMed

Jeng, M-S; Ng, N K; Ng, P K L

2004-12-23

The crab Xenograpsus testudinatus lives at enormously high densities around the sulphur-rich hydrothermal vents found in shallow waters off Taiwan, even though this acidic environment is low in nutrients. Here we show that these crabs swarm out of their crevices at slack water and feed on the vast numbers of zooplankton that are killed by the vents' sulphurous plumes, and that rain down like marine 'snow'. This opportunistic feeding behaviour explains how the crabs are able to survive in the adverse toxic environment of these shallow hydrothermal vents.

Copepod colonization of organic and inorganic substrata at a deep-sea hydrothermal vent site on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Plum, Christoph; Pradillon, Florence; Fujiwara, Yoshihiro; Sarrazin, Jozée

2017-03-01

The few existing studies on deep-sea hydrothermal vent copepods indicate low connectivity with surrounding environments and reveal high endemism among vents. However, the finding of non-endemic copepod species in association with engineer species at different reduced ecosystems poses questions about the dispersal of copepods and the colonization of hydrothermal vents as well as their ecological connectivity. The objective of this study is to understand copepod colonization patterns at a hydrothermal vent site in response to environmental factors such as temperature and fluid flow as well as the presence of different types of substrata. To address this objective, an in situ experiment was deployed using both organic (woods, pig bones) and inorganic (slates) substrata along a gradient of hydrothermal activity at the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). The substrata were deployed in 2011 during the MoMARSAT cruise and were recovered after two years in 2013. Overall, copepod density showed significant differences between substrata types, but was similar among different hydrothermal activity regimes. Highest densities were observed on woods at sites with moderate or low fluid input, whereas bones were the most densely colonized substrata at the 2 sites with higher hydrothermal influence. Although differences in copepod diversity were not significant, the observed trends revealed overall increasing diversity with decreasing temperature and fluid input. Slates showed highest diversity compared to the organic substrata. Temperature and fluid input had a significant influence on copepod community composition, resulting in higher similarity among stations with relatively high and low fluid inputs, respectively. While vent-specialists such as dirivultids and the tegastid Smacigastes micheli dominated substrata at high vent activity, the experiment demonstrated increasing abundance and dominance of non-vent taxa with decreasing temperature and fluid input. Effects of the substratum type on community composition were not significant, although at sites with moderate or low fluid input, woods exhibited distinctive communities with high densities and relative abundance of the taxon Nitocrella sp. In conclusion, copepod colonization and species composition were mainly influenced by hydrothermal fluid input and temperature rather than the type of substratum. The outcome of this study provides fundamental knowledge to better understand copepod colonization at hydrothermal vents.

Discovery of a black smoker vent field and vent fauna at the Arctic Mid-Ocean Ridge

PubMed Central

Pedersen, Rolf B.; Rapp, Hans Tore; Thorseth, Ingunn H.; Lilley, Marvin D.; Barriga, Fernando J. A. S.; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Früh-Green, Gretchen L.; Jorgensen, Steffen L.

2010-01-01

The Arctic Mid-Ocean Ridge (AMOR) represents one of the most slow-spreading ridge systems on Earth. Previous attempts to locate hydrothermal vent fields and unravel the nature of venting, as well as the provenance of vent fauna at this northern and insular termination of the global ridge system, have been unsuccessful. Here, we report the first discovery of a black smoker vent field at the AMOR. The field is located on the crest of an axial volcanic ridge (AVR) and is associated with an unusually large hydrothermal deposit, which documents that extensive venting and long-lived hydrothermal systems exist at ultraslow-spreading ridges, despite their strongly reduced volcanic activity. The vent field hosts a distinct vent fauna that differs from the fauna to the south along the Mid-Atlantic Ridge. The novel vent fauna seems to have developed by local specialization and by migration of fauna from cold seeps and the Pacific. PMID:21119639

Signs of Recent Volcanism and Hydrothermal Activity Along the Eastern Segment of the Galapagos Spreading Center

NASA Astrophysics Data System (ADS)

Raineault, N.; Smart, C.; Mayer, L. A.; Ballard, R. D.; Fisher, C. R.; Marsh, L.; Shank, T. M.

2016-12-01

Since the initial discovery of the Galápagos Spreading Center (GSC) vents in 1977, large-scale disturbances resulting from eruptive and tectonic activity have both destroyed and created vent habitats along the GSC. In 2015, the E/V Nautilus returned to the GSC with remotely operated vehicles (ROVs) to explore 17 kilometers of the rift valley from the Rosebud site in the west, to a previously unexplored temperature anomaly east of the Tempus Fugit vent site. In the years to over a decade since scientists last visited the Rosebud, Rose Garden, and Tempus Fugit sites, there were many changes. Most notably, the Rosebud site, where scientists found a nascent vent community and left site markers in 2002, was apparently covered with glassy basaltic sheet flows. In addition to visual exploration, oceanographic sensor measurements and direct sampling, we used the ROV Hercules imaging suite, comprised of stereo cameras and a structured light laser sensor to map an area of diffuse flow in the Tempus Fugit field (100 m x 150 m). The centimeter-level photographic and bathymetric maps created with this system, along with ROV HD video, samples, and environmental sensors, documented hydrothermal activity and changes in biological community structure (e.g., Riftia tubeworms observed in nascent stages of community development in 2011 were now, in 2015, in greater abundance (with tubes almost 4 m in length). The detection of active venting and associated faunal assemblages will provide insight into the temporal and spatial variability of venting activity at the Tempus Fugit site. On a visual survey of the Rift east of the Tempus Fugit site, extinct sulfide chimney structures were discovered and sampled. There were several chimneys and sulfide deposits in a span of over 8 km that ranged in height from over a half meter to 1.5 m tall. Diffuse flow hosting white and blue bacterial mats was observed near the chimneys complexes. The base of a large chimney structure, venting white fluids, as well as adjacent chemically-stained sediments supported vent-endemic fauna including the Pompeii worm (Alvinella pompejana) and other polychaete worms, along with pycnogonids, rat-tail fish, and galatheid crabs. This discovery provided the first evidence that the eastern segment of the GSC may have contained high-temperature, black smoker vents.

Bacterial and archaeal communities in the deep-sea sediments of inactive hydrothermal vents in the Southwest India Ridge

NASA Astrophysics Data System (ADS)

Zhang, Likui; Kang, Manyu; Xu, Jiajun; Xu, Jian; Shuai, Yinjie; Zhou, Xiaojian; Yang, Zhihui; Ma, Kesen

2016-05-01

Active deep-sea hydrothermal vents harbor abundant thermophilic and hyperthermophilic microorganisms. However, microbial communities in inactive hydrothermal vents have not been well documented. Here, we investigated bacterial and archaeal communities in the two deep-sea sediments (named as TVG4 and TVG11) collected from inactive hydrothermal vents in the Southwest India Ridge using the high-throughput sequencing technology of Illumina MiSeq2500 platform. Based on the V4 region of 16S rRNA gene, sequence analysis showed that bacterial communities in the two samples were dominated by Proteobacteria, followed by Bacteroidetes, Actinobacteria and Firmicutes. Furthermore, archaeal communities in the two samples were dominated by Thaumarchaeota and Euryarchaeota. Comparative analysis showed that (i) TVG4 displayed the higher bacterial richness and lower archaeal richness than TVG11; (ii) the two samples had more divergence in archaeal communities than bacterial communities. Bacteria and archaea that are potentially associated with nitrogen, sulfur metal and methane cycling were detected in the two samples. Overall, we first provided a comparative picture of bacterial and archaeal communities and revealed their potentially ecological roles in the deep-sea environments of inactive hydrothermal vents in the Southwest Indian Ridge, augmenting microbial communities in inactive hydrothermal vents.

Zones of life in the subsurface of hydrothermal vents: A synthesis

NASA Astrophysics Data System (ADS)

Larson, B. I.; Houghton, J.; Meile, C. D.

2011-12-01

Subsurface microbial communities in Mid-ocean Ridge (MOR) hydrothermal systems host a wide array of unique metabolic strategies, but the spatial distribution of biogeochemical transformations is poorly constrained. Here we present an approach that reexamines chemical measurements from diffuse fluids with models of convective transport to delineate likely reaction zones. Chemical data have been compiled from bare basalt surfaces at a wide array of mid-ocean ridge systems, including 9°N, East Pacific Rise, Axial Seamount, Juan de Fuca, and Lucky Strike, Mid-Atlantic Ridge. Co-sampled end-member fluid from Ty (EPR) was used to constrain reaction path models that define diffuse fluid compositions as a function of temperature. The degree of mixing between hot vent fluid (350 deg. C) and seawater (2 deg. C) governs fluid temperature, Fe-oxide mineral precipitation is suppressed, and aqueous redox reactions are prevented from equilibrating, consistent with sluggish kinetics. Quartz and pyrite are predicted to precipitate, consistent with field observations. Most reported samples of diffuse fluids from EPR and Axial Seamount fall along the same predicted mixing line only when pyrite precipitation is suppressed, but Lucky Strike fluids do not follow the same trend. The predicted fluid composition as a function of temperature is then used to calculate the free energy available to autotrophic microorganisms for a variety of catabolic strategies in the subsurface. Finally, the relationships between temperature and free energy is combined with modeled temperature fields (Lowell et al., 2007 Geochem. Geophys., Geosys.) over a 500 m x 500 m region extending downward from the seafloor and outward from the high temperature focused hydrothermal flow to define areas that are energetically most favorable for a given metabolic process as well as below the upper temperature limit for life (~120 deg. C). In this way, we can expand the relevance of geochemical model predictions of bioenergetics by predicting functionally-defined 'Zones of Life' and placing them spatially within the boundary of the 120 deg. C isotherm, estimating the extent of subsurface biosphere beneath mid-ocean ridge hydrothermal systems. Preliminary results indicate that methanogenesis yields the most energy per kg of vent fluid, consistent with the elevated CH4(aq) seen at all three sites, but may be constrained by temperatures too hot for microbial life while available energy from the oxidation of Fe(II) peaks near regions of the crust that are more hospitable.

Distribution and chemistry of suspended particles from an active hydrothermal vent site on the Mid-Atlantic Ridge at 26°N

NASA Astrophysics Data System (ADS)

Trocine, Robert P.; Trefry, John H.

1988-04-01

Suspended particles were collected from an area of active hydrothermal venting at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge and analyzed for Fe, Mn, Cd, Zn, Cu, V, Ni, Cr, Pb, Mg, Ca, Al and Si. Rapid advection of vent-derived precipitates produced a lens with total suspended matter (TSM) loadings of 14-60 μg/l at 200-700 m above the seafloor; TSM concentrations > 60 μg/l were observed only at near-vent sites. The distribution of suspended particles correlated well with increased dissolved Mn concentrations and particulate Fe values near the vent source. Particulate Fe values decreased linearly relative to TSM concentrations as hydrothermal precipitates mixed with background suspended matter. Near-vent precipitates were characterized by up to 35% Fe, 2% Zn, 0.6% Cu and > 100 μg/g Cd. In comparison to Fe, particulate Cd, Zn and Cu values decreased dramatically away from the vent source. This trend supports differential settling and/or dissolution of Cd-, Zn- and Cu-bearing phases. Particulate Mn and Fe values were inversely related with only 50 μg Mn/g in the near-vent particles. At near-vent sites, > 99% of the total Mn was in solution; this fraction decreased to 75-80% at background TSM values. In contrast to Cd, Zn and Cu, particulate V levels show a continuous, linear decrease with particulate Fe values. This trend is explained by adsorption of V on Fe-oxides in the vent plume. Scavenging of Cr, Pb and Mg by hydrothermal precipitates is also suggested by the data. Nickel and Al values were low in near-vent particles at < 100 and < 3 μg/g, respectively. The complementary behavior of dissolved Mn and particulate trace metals provides a useful framework for studying broad aspects of hydrothermal plume processes.

Molecular diversity and distribution pattern of ciliates in sediments from deep-sea hydrothermal vents in the Okinawa Trough and adjacent sea areas

NASA Astrophysics Data System (ADS)

Zhao, Feng; Xu, Kuidong

2016-10-01

In comparison with the macrobenthos and prokaryotes, patterns of diversity and distribution of microbial eukaryotes in deep-sea hydrothermal vents are poorly known. The widely used high-throughput sequencing of 18S rDNA has revealed a high diversity of microeukaryotes yielded from both living organisms and buried DNA in marine sediments. More recently, cDNA surveys have been utilized to uncover the diversity of active organisms. However, both methods have never been used to evaluate the diversity of ciliates in hydrothermal vents. By using high-throughput DNA and cDNA sequencing of 18S rDNA, we evaluated the molecular diversity of ciliates, a representative group of microbial eukaryotes, from the sediments of deep-sea hydrothermal vents in the Okinawa Trough and compared it with that of an adjacent deep-sea area about 15 km away and that of an offshore area of the Yellow Sea about 500 km away. The results of DNA sequencing showed that Spirotrichea and Oligohymenophorea were the most diverse and abundant groups in all the three habitats. The proportion of sequences of Oligohymenophorea was the highest in the hydrothermal vents whereas Spirotrichea was the most diverse group at all three habitats. Plagiopyleans were found only in the hydrothermal vents but with low diversity and abundance. By contrast, the cDNA sequencing showed that Plagiopylea was the most diverse and most abundant group in the hydrothermal vents, followed by Spirotrichea in terms of diversity and Oligohymenophorea in terms of relative abundance. A novel group of ciliates, distinctly separate from the 12 known classes, was detected in the hydrothermal vents, indicating undescribed, possibly highly divergent ciliates may inhabit this environment. Statistical analyses showed that: (i) the three habitats differed significantly from one another in terms of diversity of both the rare and the total ciliate taxa, and; (ii) the adjacent deep sea was more similar to the offshore area than to the hydrothermal vents. In terms of the diversity of abundant taxa, however, there was no significant difference between the hydrothermal vents and the adjacent deep sea, both of which differed significantly from the offshore area. As abundant ciliate taxa can be found in several sampling sites, they are likely adapted to large environmental variations, while rare taxa are found in specific habitat and thus are potentially more sensitive to varying environmental conditions.

First columbellid species (Gastropoda: Buccinoidea) from deep-sea hydrothermal vents, discovered in Okinawa Trough, Japan.

PubMed

Chen, Chong; Watanabe, Hiromi Kayama; Araya, Juan Francisco

2017-12-12

The molluscan diversity of deep-sea chemosynthetic ecosystems in Japan has been in general well documented with about 80 described species, of which over half are gastropods (Sasaki et al. 2005; Fujikura et al. 2012; Sasaki et al. 2016). Recently, however, a number of novel hydrothermal vent sites were discovered in the area using multibeam echo-sounding (Nakamura et al. 2015), providing opportunities for new discoveries. As a part of ongoing studies documenting the biodiversity of such sites, we present the first record of Columbellidae from hydrothermal vents, with a new species recovered from Natsu and Aki sites, in the Iheya North hydrothermal field (for map and background on the vent field see Nakamura et al. 2015).

Detecting deep sea hydrothermal vents with a split-beam echosounder

NASA Astrophysics Data System (ADS)

Gray, L. M.; Jerram, K.

2016-12-01

In May 2016, the NOAA Office of Exploration and Research exploration vessel, Okeanos Explorer, conducted a remotely operated vehicle (ROV) dive on a series of active `black smoker' hydrothermal vents at 3,300 m depth in the western Pacific Ocean near the Mariana Trench. The ROV system traversed 800 m along the seafloor and detected three distinct vent sites. The vent chimneys ranged in heights from 5 m to 30 m above the seafloor and vent fluid temperatures were measured as high as 337 °C. Immediately following the ROV dive, the Okeanos Explorer mapped the vent field with an 18 kHz split-beam echosounder traditionally used for fishery research and a 30 kHz multibeam echosounder with midwater capability. Six passes were made over the field, transiting at 4-5 knots on various headings. There was a clear and repeatable signal in the split-beam echogram from the venting but less obvious indication in the multibeam data. `Black smokers' have traditionally been detected using repeat conductivity-temperature-depth (CTD) `tow-yo' casts. Our field observations suggest an alternative, and potentially more efficient, method of detecting hydrothermal vent plumes within the beamwidth of the split-beam echosounder to inform ROV dive plans. Methods previously applied for locating marine gas seeps on the seafloor with split-beam echosounders can be applied to estimate the hydrothermal vent positions in this dataset and compared to the recorded ROV positions at each site. Additionally, assuming relatively stable venting and ambient conditions, the ROV position and CTD data recorded from the vehicles can be used to better understand the observed midwater acoustic backscatter signatures of the hydrothermal vent plumes.

Effect of sulfide, osmotic, and thermal stresses on taurine transporter mRNA levels in the gills of the hydrothermal vent-specific mussel Bathymodiolus septemdierum.

PubMed

Nakamura-Kusakabe, Ikumi; Nagasaki, Toshihiro; Kinjo, Azusa; Sassa, Mieko; Koito, Tomoko; Okamura, Kei; Yamagami, Shosei; Yamanaka, Toshiro; Tsuchida, Shinji; Inoue, Koji

2016-01-01

Hydrothermal vent environmental conditions are characterized by high sulfide concentrations, fluctuating osmolality, and irregular temperature elevations caused by vent effluents. These parameters represent potential stressors for organisms that inhabit the area around hydrothermal vents. Here, we aimed to obtain a better understanding of the adaptation mechanisms of marine species to hydrothermal vent environments. Specifically, we examined the effect of sulfide, osmolality, and thermal stress on the expression of taurine transporter (TAUT) mRNA in the gill of the deep-sea mussel Bathymodiolus septemdierum, which is a dominant species around hydrothermal vent sites. We analyzed TAUT mRNA levels by quantitative real-time polymerase chain reaction (PCR) in the gill of mussels exposed to sulfide (0.1 or 1mg/L Na2S·9H2O), hyper- (115% seawater) and hypo- (97.5%, 95.5%, and 85% seawater) osmotic conditions, and thermal stresses (12°C and 20°C) for 24 and 48h. The results showed that mussels exposed to relatively low levels of sulfide (0.1mg/L) and moderate heat stress (12°C) exhibited higher TAUT mRNA levels than the control. Although hyper- and hypo-osmotic stress did not significantly change TAUT mRNA levels, slight induction was observed in mussels exposed to low osmolality. Our results indicate that TAUT is involved in the coping mechanism of mussels to various hydrothermal vent stresses. Copyright © 2015 Elsevier Inc. All rights reserved.

Water column imaging on hydrothermal vent in Central Indian Ridge

NASA Astrophysics Data System (ADS)

Koh, J.; Park, Y.

2017-12-01

Water column imaging with Multibeam echosounder systems (MBES) is recently becoming of increasing interest for oceanographic studies. Especially gas bubbles and hot water exposed from hydrothermal vents make acoustic impedance anomalies in cold seawater, water column imaging is very useful for the researchers who want to detect some kinds of hydrothermal activity. We conducted a hydrothermal exploration program, called "INVENT17", using the MBES system, KONGBERG EM122 (12kHz, 1°×1°), mounted on R/V ISABU and we deployed other equipments including video guided hydraulic grab, tow-yo CTD and general CTD with MAPR (Miniature Autonomous Plume Recorder) in 2017. First, to evaluate its capabilities of detection of hydrothermal vent, the surveys using the MBES were conducted at the Solitaire Field, previously identified hydrothermal area of the Central Indian Ridge. The bathymetric data obtained from MBES provided information about detailed morphology of seafloor, but we were not able to achieve the information from the water column imaging data. But the clue of existence of active hydrothermal vent was detected through the values of ΔNTU, dEh/dt, and OPR gained from MAPR, the data means that the hydrothermal activity affects 100m from the seafloor. It could be the reason that we can't find the hydrothermal activity because the range resolution of water column imaging is pretty rough so that the size of 100m-scaled activity has low possibility to distinguish from seafloor. The other reason is there are no sufficient objects to cause strong scattering like as CO2 bubbles or droplets unlike in the mid-Okinawa Trough. And this suggests that can be a important standard to identify properties of hydrothermal vent sites depending on the presence of scattering objects in water mass. To justify this, we should perform more chemical analysis of hot water emanating from hydrothermal vent and collected several bottles of water sample to do that.

Geochemistry of High Temperature Vent Fluids in Yellowstone Lake: Dissolved Carbon and Sulfur Concentrations and Isotopic Data

NASA Astrophysics Data System (ADS)

Cino, C.; Seyfried, W. E., Jr.; Tan, C.; Fu, Q.

2017-12-01

Yellowstone National Park is a dynamic environment home to an array of geysers, hot springs, and hydrothermal vents fueled by the underlying continental magmatic intrusion. Yellowstone Lake vent fluids accounts for approximately 10% of the total geothermal flux for all of Yellowstone National Park. Though studying this remote hydrothermal system poses severe challenges, it provides an excellent natural laboratory to research hydrothermal fluids that undergo higher pressure and temperature conditions in an environment largely shielded from atmospheric oxygen. The location of these vents also provides chemistry that is characteristic of fluids deeper in the Yellowstone hydrothermal system. In August 2016, hydrothermal fluids were collected from the Stevenson Island vents in collaboration with the Hydrothermal Dynamics of Yellowstone Lake (HD-YLAKE) project using novel sampling techniques and monitoring instrumentation. The newly built ROV Yogi was deployed to reach the vents in-situ with temperatures in excess of 151oC at 100-120 m depth, equipped with a 12-cylinder isobaric sampler to collect the hydrothermal fluids. Results from geochemical analyses indicate the fluids are rich in gases such as CO2, CH4, and H2S, with sample concentrations of approximately 12 mM, 161 μm, and 2.1 mM respectively. However, lake water mixing with the hydrothermal endmember fluid likely diluted these concentrations in the collected samples. Isotopic analyses indicate CO2 has a δ13C of -6 indicating magmatic origins, however the CH4 resulted in a δ13C of -65 which is in the biological range. This biogenic signature is likely due to the pyrolysis of immature organic matter in the lake bottom sediment, since the high temperatures measured for the fluids would not allow the presence of methanogens. H2S concentrations have not been previously measured for the hydrothermal fluids in Yellowstone Lake, and our vent fluid samples indicate significantly higher H2S concentrations than reported for subaerial vents. The cause of these measured high dissolved H2S concentrations in Yellowstone Lake may result from temperature and/or redox effects.

Bioavailable metals and cellular effects in the digestive gland of marine limpets living close to shallow water hydrothermal vents.

PubMed

Cunha, Luís; Amaral, André; Medeiros, Vera; Martins, Gustavo M; Wallenstein, Francisco F M M; Couto, Ruben P; Neto, Ana I; Rodrigues, Armindo

2008-04-01

The pressure exerted by shallow water hydrothermal vents on edible gastropods and their cellular responses triggered by these stresses are almost unknown. The aims of this study were to evaluate the bioavailability of metals in the Macaronesian endemic limpet Patella candei gomesii living close to shallow water hydrothermal vents, and the structural differences in their digestive gland as well as the levels of apoptosis in that organ. Limpets were sampled in four sites, two with the presence of hydrothermalism and the other two without it. Whole body concentrations of several metals (Ca, Cd, Cs, Co, Cu, Fe, Hg, Mg, Mn, Pb, Rb, Se, Sr, and Zn) were obtained, morphometry analysis of the digestive gland and TUNEL test for apoptosis were also performed. Results revealed that the presence of shallow water hydrothermal vents is a source of chronic metal stress to limpets, imposing modifications in the morphometry and cell composition of the digestive gland of those limpets that may constitute cell and tissue adaptations to the environment they live in. This study sets up new baseline data for further research on the influence of shallow water hydrothermal vents over communities living in these habitats.

The impact of marine shallow-water hydrothermal venting on arsenic and mercury accumulation by seaweed Sargassum sinicola in Concepcion Bay, Gulf of California.

PubMed

Leal-Acosta, María Luisa; Shumilin, Evgueni; Mirlean, Nicolai; Delgadillo-Hinojosa, Francisco; Sánchez-Rodríguez, Ignacio

2013-02-01

The influence of hydrothermal venting activity on arsenic (As) and mercury (Hg) accumulation was investigated in the shallow-water marine ecosystem of Concepcion Bay in the western Gulf of California. Geochemical data indicate that the marine shallow-water hydrothermal system of the Mapachitos site is a source of As and Hg for the water, sediment and algae collected along a transect moving across the western region of the bay. Although a small proportion of As and Hg precipitates close to the hydrothermal vent, both elements remain largely in the dissolved fraction, spreading a long distance from the source. The brown seaweed Sargassum sinicola thriving near the area of hydrothermal venting accumulates large quantities of As (above 600 mg kg (-1)), surpassing its typical concentration in the genus Sargassum by an order of magnitude. In contrast to As, the seaweed does not significantly accumulate Hg.

Distribution of Hydrothermal Activity at the Lau ISS: Possible Controlling Parameters

NASA Astrophysics Data System (ADS)

Martinez, F.; Baker, E. T.; Resing, J. A.; Edwards, M. H.; Walker, S. L.; Buck, N.

2008-12-01

Seismic tomographic studies of intermediate to fast spreading rate mid-ocean ridges (MORs) interpret zones of rapid crustal cooling a few (3-4) km off axis surrounding the axial seismic low velocity zone (LVZ). These zones of rapid cooling also broadly correlate with the initiation and growth of large abyssal hill faults. The close association of both high thermal gradients and development of fault permeability at crustal scales suggests the hypothesis that these areas may be favorable locations for off-axis high temperature hydrothermal activity. In March-May 2008 on R/V Kilo Moana we conducted a near-bottom sidescan sonar and oceanographic survey along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the Lau back-arc basin to map the distribution of hydrothermal activity within this region. The survey utilized the deep-towed DSL120A (IMI120) sonar, an array of miniature autonomous plume recorders (MAPRs) attached to the tow cable and tethered beneath the sonar's depressor weight, an in situ chemical scanner (VISA) and 23 CTD hydrocasts (see Baker et al., this session). At the ELSC the survey spanned ~100 x 10 km area encompassing the ABE, Tow Cam and Kilo Moana vent fields with ~ 1 km spaced lines overall and ~500 m spaced lines in the area of the ABE vent field. On the VFR the survey spanned a distance of ~100 km along axis by ~5 km across axis with 700 m spaced lines encompassing the Vai Lili, Mariner and Tui Malila vent sites. Initial results identified particle plumes, indicative of high temperature venting, only within about a km of the ridge axis at the ELSC and VFR with possible diffuse venting indicated by MAPR oxidation-reduction potential (ORP) measurements at flank sites at VFR. The expanded sonar coverage better defines the volcano-tectonic context of the hydrothermal signals and previously mapped vent sites. Initial results suggest, however, no high-T venting more than about 1 km from the ridge axis, an apparently negative test of the above hypothesis. This may suggest that hydrothermal fluids are efficiently channeled to the axis even if cooling off-axis crustal regions. Alternatively, at the back-arc VFR/ELSC subduction controls on magmatic productivity may play an important role in modifying the usual relationships observed at MORs among spreading rate, seismic low velocity zone width, faulting, sedimentation and hydrothermal activity. For example, the fast spreading ELSC is magmatically deficient for its spreading rate, forms a deep faulted axial floor and has no continuous axial magma lens seismic reflector. This may lead to a narrower LVZ at the ELSC relative to MORs spreading at the same rate. At the intermediate rate and arc- proximal VFR excess magmatic productivity and volatile-rich volcanics form a peaked shallow axis, few flanking faults and a sediment drape of volcaniclastics from the ridge axis (and nearby arc volcanoes). These effects may act to suppress fault-related permeability on ridge flanks or may rapidly blanket ridge-flanking hydrothermal systems. Some of these issues may be further clarified when planned seismic tomographic and moored hydrophone studies are carried out beginning next year at the ELSC/VFR.

Sources of organic carbon for Rimicaris hybisae: Tracing individual fatty acids at two hydrothermal vent fields in the Mid-Cayman rise

NASA Astrophysics Data System (ADS)

Streit, Kathrin; Bennett, Sarah A.; Van Dover, Cindy L.; Coleman, Max

2015-06-01

Hydrothermal vents harbor ecosystems mostly decoupled from organic carbon synthesized with the energy of sunlight (photosynthetic carbon source) but fueled instead by oxidation of reduced compounds to generate a chemosynthetic carbon source. Our study aimed to disentangle photosynthetic and chemosynthetic organic carbon sources for the shrimp species Rimicaris hybisae, a primary consumer presumed to obtain its organic carbon mainly from ectosymbiotic chemoautotrophic bacteria living on its gill cover membrane. To provide ectosymbionts with ideal conditions for chemosynthesis, these shrimp live in dense clusters around vent chimneys; they are, however, also found sparsely distributed adjacent to diffuse vent flows, where they might depend on alternative food sources. Densely and sparsely distributed shrimp were sampled and dissected into abdominal tissue and gill cover membrane, covered with ectosymbiotic bacteria, at two hydrothermal vent fields in the Mid-Cayman rise that differ in vent chemistry. Fatty acids (FA) were extracted from shrimp tissues and their carbon isotopic compositions assessed. The FA data indicate that adult R. hybisae predominantly rely on bacteria for their organic carbon needs. Their FA composition is dominated by common bacterial FA of the n7 family (~41%). Bacterial FA of the n4 FA family are also abundant and found to constitute good biomarkers for gill ectosymbionts. Sparsely distributed shrimp contain fractions of n4 FA in gill cover membranes ~4% lower than densely packed ones (~18%) and much higher fractions of photosynthetic FA in abdominal tissues, ~4% more (compared with 1.6%), suggesting replacement of ectosymbionts along with exoskeletons (molt), while they take up alternative diets of partly photosynthetic organic carbon. Abdominal tissues also contain photosynthetic FA from a second source taken up presumably during an early dispersal phase and still present to c. 3% in adult shrimp. The contribution of photosynthetic carbon to the FA pool of adult R. hybisae is, however, overall small (max. 8%). Significant differences in carbon isotopic values of chemosynthetically derived FA between vent fields suggest that different dominant C fixation pathways are being used.

The Marine Geochemistry of Iron and Iron Isotopes

DTIC Science & Technology

2004-09-01

suspension of sediments, and hydrothermal vents. A schematic of the Fe cycle in the open ocean is shown in Figure 1.1. Fe concentrations are highest near...than 2% of their coastal values 100 km from the California continental margin (JOHNSON et al., 1997). Hydrothermal input of Fe is believed to be...important only near its sources (mostly in the deep ocean) because most of the Fe from hydrothermal vents precipitates near the vents and ridge axis (DE

Extensive deep-sea dispersal of postlarval shrimp from a hydrothermal vent

NASA Astrophysics Data System (ADS)

Herring, P. J.; Dixon, D. R.

1998-12-01

Hydrothermal vent fields on the Mid-Atlantic Ridge (MAR) are small (no more than 0.1-1.0 km 2) and widely spaced (a reported average of one field per 175 km between 11°N and 40°N). Their faunas are similar and usually dominated by shrimp of the family Bresiliidae. Little is known about the way these animals (and other members of the vent fauna) disperse and colonize new vents. Vent shrimp juveniles have been taken close to certain vent sites, and in midwater, but their larvae and postlarvae have not been captured. We report here that bresiliid shrimp postlarvae are very widely dispersed around the Broken Spur vent field and extend into the next MAR segment and the Atlantis Fracture Zone beyond. The populations show density gradients declining both vertically and horizontally from the vent site, in contrast to the overall pelagic biomass. This is the furthest recorded dispersal (>100 km) of identified larvae from a hydrothermal vent and is sufficient to give them access to adjacent vent fields and thus the scope for colonising new sites.

Geologic setting of the Snake Pit hydrothermal site: An active vent field on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Karson, Jeffrey A.; Brown, Jennifer R.

1988-03-01

The Snake Pit Hydrothermal Site lies on the axis of the Mid-Atlantic Ridge at 23°22' N latitude, about 30 km south of the Kane Transform Intersection. Active ‘black smoker’ vents and a surrounding field of hydrothermal sediment occur at the crest of a laterally extensive neovolcanic ridge. It is one of the first active hydrothermal vent fields to be found on a slow-spreading ridge axis and despite significant differences in its geologic setting from those of the East Pacific Rise, has many similarities to its fast-spreading counterparts. Although preliminary reports have documented many interesting aspects of these vents and their surroundings, new data collected from the manned submersible ALVIN and the deep-towed ANGUS camera system define the regional tectonic setting as well as the local geologic environment of this fascinating area. The Snake Pit vents are located on a local peak of a volcanic constructional ridge at a depth of 3450 m, 700 800 m deeper than vents known from the East Pacific Rise, Galapagos, or Juan de Fuca spreading centers. The vent field is at least 600 m long and up to 200 m wide and is covered by a thick blanket of greenish to yellow-orange hydrothermal sediment. Both active and extinct vents are perched along the crests of steep-sided sulfide mounds that reach heights of over 40 m. High-temperature (350° C) fluids are vented from black smoker chimneys and low-temperature (226° C) fluids seep from sulphide domes and subordinate anhydrite constructions. Water temperatures, flow rates, fluid chemistries, and mineralization are strikingly similar to vents of faster spreading ridge crests; however, a somewhat distinct fauna inhabit the area.

Discovery of a new hydrothermal vent based on an underwater, high-resolution geophysical survey

NASA Astrophysics Data System (ADS)

Nakamura, Kentaro; Toki, Tomohiro; Mochizuki, Nobutatsu; Asada, Miho; Ishibashi, Jun-ichiro; Nogi, Yoshifumi; Yoshikawa, Shuro; Miyazaki, Jun-ichi; Okino, Kyoko

2013-04-01

A new hydrothermal vent site in the Southern Mariana Trough has been discovered using acoustic and magnetic surveys conducted by the Japan Agency for Marine-Earth Science and Technology's (JAMSTEC) autonomous underwater vehicle (AUV), Urashima. The high-resolution magnetic survey, part of a near-bottom geophysical mapping around a previously known hydrothermal vent site, the Pika site, during the YK09-08 cruise in June-July 2009, found that a clear magnetization low extends ˜500 m north from the Pika site. Acoustic signals, suggesting hydrothermal plumes, and 10 m-scale chimney-like topographic highs were detected within this low magnetization zone by a 120 kHz side-scan sonar and a 400 kHz multibeam echo sounder. In order to confirm the seafloor sources of the geophysical signals, seafloor observations were carried out using the deep-sea manned submersible Shinkai 6500 during the YK 10-10 cruise in August 2010. This discovered a new hydrothermal vent site (12°55.30'N, 143°38.89'E; at a depth of 2922 m), which we have named the Urashima site. This hydrothermal vent site covers an area of approximately 300 m×300 m and consists of black and clear smoker chimneys, brownish-colored shimmering chimneys, and inactive chimneys. All of the fluids sampled from the Urashima and Pika sites have chlorinity greater than local ambient seawater, suggesting subseafloor phase separation or leaching from rocks in the hydrothermal reaction zone. End-member compositions of the Urashima and Pika fluids suggest that fluids from two different sources feed the two sites, even though they are located on the same knoll and separated by only ˜500 m. We demonstrate that investigations on hydrothermal vent sites located in close proximity to one another can provide important insights into subseafloor hydrothermal fluid flow, and also that, while such hydrothermal sites are difficult to detect by conventional plume survey methods, high-resolution underwater geophysical surveys provide an effective means.

Community Structure Comparisons of Hydrothermal Vent Microbial Mats Along the Mariana Arc and Back-arc

NASA Astrophysics Data System (ADS)

Hager, K. W.; Fullerton, H.; Moyer, C. L.

2015-12-01

Hydrothermal vents along the Mariana Arc and back-arc represent a hotspot of microbial diversity that has not yet been fully recognized. The Mariana Arc and back-arc contain hydrothermal vents with varied vent effluent chemistry and temperature, which translates to diverse community composition. We have focused on iron-rich sites where the dominant primary producers are iron oxidizing bacteria. Because microbes from these environments have proven elusive in culturing efforts, we performed culture independent analysis among different microbial communities found at these hydrothermal vents. Terminal-restriction fragment length polymorphism (T-RFLP) and Illumina sequencing of small subunit ribosomal gene amplicons were used to characterize community members and identify samples for shotgun metagenomics. Used in combination, these methods will better elucidate the composition and characteristics of the bacterial communities at these hydrothermal vent systems. The overarching goal of this study is to evaluate and compare taxonomic and metabolic diversity among different communities of microbial mats. We compared communities collected on a fine scale to analyze the bacterial community based on gross mat morphology, geography, and nearby vent effluent chemistry. Taxa richness and evenness are compared with rarefaction curves to visualize diversity. As well as providing a survey of diversity this study also presents a juxtaposition of three methods in which ribosomal small subunit diversity is compared with T-RFLP, next generation amplicon sequencing, and metagenomic shotgun sequencing.

Diverse styles of submarine venting on the ultra-slow spreading Mid-Cayman Rise (Invited)

NASA Astrophysics Data System (ADS)

German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J.; Mercier de Lepinay, B. F.; Nakamura, K.; Seewald, J.; Smith, J.; Sylva, S.; van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

2010-12-01

Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise collected using a combination of CTD-rosette operations and dives of the Hybrid Remotely Operated Vehicle (HROV) Nereus in 2009 followed by shore based work-up of samples for geochemical and microbiological analyses. Our data indicate that the Mid-Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.

Discovery of New Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18°–20°S

PubMed Central

Nakamura, Kentaro; Watanabe, Hiromi; Miyazaki, Junichi; Takai, Ken; Kawagucci, Shinsuke; Noguchi, Takuro; Nemoto, Suguru; Watsuji, Tomo-o; Matsuzaki, Takuya; Shibuya, Takazo; Okamura, Kei; Mochizuki, Masashi; Orihashi, Yuji; Ura, Tamaki; Asada, Akira; Marie, Daniel; Koonjul, Meera; Singh, Manvendra; Beedessee, Girish; Bhikajee, Mitrasen; Tamaki, Kensaku

2012-01-01

Indian Ocean hydrothermal vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean hydrothermal systems. In particular, since its discovery in 2001, much attention has been paid to a so-called ‘scaly-foot’ gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean hydrothermal vents, only two hydrothermal vent fields have been investigated in the Indian Ocean. Here we report two newly discovered hydrothermal vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR hydrothermal environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of ‘scaly-foot’ gastropod has been found at the Solitaire field. The newly discovered ‘scaly-foot’ gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of ‘scaly-foot’ gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to ‘scaly-foot’ gastropods. Our new findings at the two newly discovered hydrothermal vent sites provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean. PMID:22431990

Imaging hydrothermal roots along the Endeavour segment of the Juan de Fuca ridge using elastic full waveform inversion.

NASA Astrophysics Data System (ADS)

Arnulf, A. F.; Harding, A. J.; Kent, G. M.

2016-12-01

The Endeavour segment is a 90 km-long, medium-spreading-rate, oceanic spreading center located on the northern Juan de Fuca ridge (JDFR). The central part of this segment forms a 25-km-long volcanic high that hosts five of the most hydrothermally active vent fields on the MOR system, namely (from north to south): Sasquatch, Salty Dawg, High Rise, Main Endeavour and Mothra. Mass, heat and chemical fluxes associated to vigorous hydrothermal venting are large, however the geometry of the fluid circulation system through the oceanic crust remains almost completely undefined. To produce high-resolution velocity/reflectivity structures along the axis of the Endeavour segment, here, we combined a synthetic ocean bottom experiment (SOBE), 2-D traveltime tomography, 2D elastic full waveform and reverse time migration (RTM). We present velocity and reflectivity sections along Endeavour segment at unprecedented spatial resolutions. We clearly image a set of independent, geometrically complex, elongated low-velocity regions linking the top of the magma chamber at depth to the hydrothermal vent fields on the seafloor. We interpret these narrow pipe-like units as focused regions of hydrothermal fluid up-flow, where acidic and corrosive fluids form pipe-like alteration zones as previously observed in Cyprus ophiolites. Furthermore, the amplitude of these low-velocity channels is shown to be highly variable, with the strongest velocity drops observed at Main Endeavour, Mothra and Salty Dawg hydrothermal vent fields, possibly suggesting more mature hydrothermal cells. Interestingly, the near-seafloor structure beneath those three sites is very similar and highlights a sharp lateral transition in velocity (north to south). On the other hand, the High-Rise hydrothermal vent field is characterized by several lower amplitudes up-flow zones and relatively slow near-surface velocities. Last, Sasquatch vent field is located in an area of high near-surface velocities and is not characterized by an obvious low-velocity up-flow region, in good agreement with an extinct vent field.

Geochemistry of hydrothermal vent fluids and its implications for subsurface processes at the active Longqi hydrothermal field, Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Ji, Fuwu; Zhou, Huaiyang; Yang, Qunhui; Gao, Hang; Wang, Hu; Lilley, Marvin D.

2017-04-01

The Longqi hydrothermal field at 49.6°E on the Southwest Indian Ridge was the first active hydrothermal field found at a bare-rock ultra-slow spreading mid-ocean ridge. Here we report the chemistry of the hydrothermal fluids, for the first time, that were collected from the S zone and the M zone of the Longqi field by gas-tight isobaric samplers by the HOV "Jiaolong" diving cruise in January 2015. According to H2, CH4 and other chemical data of the vent fluid, we suggest that the basement rock at the Longqi field is dominantly mafic. This is consistent with the observation that the host rock of the active Longqi Hydrothermal field is dominated by extensively distributed basaltic rock. It was very interesting to detect simultaneously discharging brine and vapor caused by phase separation at vents DFF6, DFF20, and DFF5 respectively, in a distance of about 400 m. Based on the end-member fluid chemistry and distance between the vents, we propose that there is a single fluid source at the Longqi field. The fluid branches while rising to the seafloor, and two of the branches reach S zone and M zone and phase separate at similar conditions of about 28-30.2 MPa and 400.6-408.3 °C before they discharge from the vents. The end-member fluid compositions of these vents are comparable with or within the range of variation of known global seafloor hydrothermal fluid chemical data from fast, intermediate and slow spreading ridges, which confirms that the spreading rate is not the key factor that directly controls hydrothermal fluid chemistry. The composition of basement rock, water-rock interaction and phase separation are the major factors that control the composition of the vent fluids in the Longqi field.

Electron microscopy study of microbial mat in the North Fiji basin hydrothermal vent

NASA Astrophysics Data System (ADS)

Park, H.; Kim, J. W.; Lee, J. W.

2017-12-01

Hydrothermal vent systems consisting of hydrothermal vent, hydrothermal sediment and microbial mat are widely spread around the ocean, particularly spreading axis, continental margin and back-arc basin. Scientists have perceived that the hydrothermal systems, which reflect the primeval earth environment, are one of the best places to reveal the origin of life and extensive biogeochemical process of microbe-mineral interaction. In the present study multiline of analytical methods (X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)) were utilized to investigate the mineralogy/chemistry of microbe-mineral interaction in hydrothermal microbial mat. Microbial mat samples were recovered by Canadian scientific submersible ROPOS on South Pacific North Fiji basin KIOST hydrothermal vent expedition 1602. XRD analysis showed that red-colored microbial mat contains Fe-oxides and Fe-oxyhydroxides. Various morphologies of minerals in the red-colored microbial mat observed by SEM are mainly showed sheath shaped, resembled with Leptothrix microbial structure, stalks shaped, similar with Marioprofundus microbial structure and globule shaped microbial structures. They are also detected with DNA analysis. The cross sectional observation of microbial structures encrusted with Fe-oxide and Fe-oxyhydroxide at a nano scale by Transmission Electron Microscopy (TEM) and Focused Ion Beam (FIB) technique was developed to verify the structural/biogeochemical properties in the microbe-mineral interaction. Systematic nano-scale measurements on the biomineralization in the microbial mat leads the understandings of biogeochemical environments around the hydrothermal vent.

Laboratory Evaluation of Laser-Induced Breakdown Spectroscopy (LIBS) as a New in situ Chemical Sensing Technique for the Deep Ocean

DTIC Science & Technology

2007-09-01

1.1.2 Advantages and Disadvantages of the LIBS Technique ..... .. 21 1.1.3 LIBS in Liquids ................................ 23 1.2 Scientific ...1.2 Scientific Application: Hydrothermal Vent Chemistry Study of in situ hydrothermal vent chemistry could benefit greatly from the develop- ment of a...4935, 1994. [50] K. L. Von Danim . Chemistry of hydrothermal vent fluids froin 90 - 100 N, East Pacific Rise: ’Time zero,’ The inmnediate posteruptive

Subsurface conditions in hydrothermal vents inferred from diffuse flow composition, and models of reaction and transport

NASA Astrophysics Data System (ADS)

Larson, B. I.; Houghton, J. L.; Lowell, R. P.; Farough, A.; Meile, C. D.

2015-08-01

Chemical gradients in the subsurface of mid-ocean ridge hydrothermal systems create an environment where minerals precipitate and dissolve and where chemosynthetic organisms thrive. However, owing to the lack of easy access to the subsurface, robust knowledge of the nature and extent of chemical transformations remains elusive. Here, we combine measurements of vent fluid chemistry with geochemical and transport modeling to give new insights into the under-sampled subsurface. Temperature-composition relationships from a geochemical mixing model are superimposed on the subsurface temperature distribution determined using a heat flow model to estimate the spatial distribution of fluid composition. We then estimate the distribution of Gibb's free energies of reaction beneath mid oceanic ridges and by combining flow simulations with speciation calculations estimate anhydrite deposition rates. Applied to vent endmembers observed at the fast spreading ridge at the East Pacific Rise, our results suggest that sealing times due to anhydrite formation are longer than the typical time between tectonic and magmatic events. The chemical composition of the neighboring low temperature flow indicates relatively uniform energetically favorable conditions for commonly inferred microbial processes such as methanogenesis, sulfate reduction and numerous oxidation reactions, suggesting that factors other than energy availability may control subsurface microbial biomass distribution. Thus, these model simulations complement fluid-sample datasets from surface venting and help infer the chemical distribution and transformations in subsurface flow.

Spatial scaling of bacterial community diversity at shallow hydrothermal vents: a global comparison

NASA Astrophysics Data System (ADS)

Pop Ristova, P.; Hassenrueck, C.; Molari, M.; Fink, A.; Bühring, S. I.

2016-02-01

Marine shallow hydrothermal vents are extreme environments, often characterized by discharge of fluids with e.g. high temperatures, low pH, and laden with elements toxic to higher organisms. They occur at continental margins around the world's oceans, but represent fragmented, isolated habitats of locally small areal coverage. Microorganisms contribute the main biomass at shallow hydrothermal vent ecosystems and build the basis of the food chain by autotrophic fixation of carbon both via chemosynthesis and photosynthesis, occurring simultaneously. Despite their importance and unique capacity to adapt to these extreme environments, little is known about the spatial scales on which the alpha- and beta-diversity of microbial communities vary at shallow vents, and how the geochemical habitat heterogeneity influences shallow vent biodiversity. Here for the first time we investigated the spatial scaling of microbial biodiversity patterns and their interconnectivity at geochemically diverse shallow vents on a global scale. This study presents data on the comparison of bacterial community structures on large (> 1000 km) and small (0.1 - 100 m) spatial scales as derived from ARISA and Illumina sequencing. Despite the fragmented global distribution of shallow hydrothermal vents, similarity of vent bacterial communities decreased with geographic distance, confirming the ubiquity of distance-decay relationship. Moreover, at all investigated vents, pH was the main factor locally structuring these communities, while temperature influenced both the alpha- and beta-diversity.

The Gondou hydrothermal field in the Ryukyu Arc: A huge hydrothermal system on the flank of a caldera volcano

NASA Astrophysics Data System (ADS)

Minami, H.; Ohara, Y.

2017-09-01

High-resolution geophysical mapping was conducted from an autonomous underwater vehicle on the flank of Daisan-Kume Knoll in the Ryukyu Arc, southwest of Japan. 1 m resolution bathymetry identified 264 spires, 173 large mounds and 268 small mounds within a depression that is up to 1600 m wide and up to 60 m deep, at water depths between 1330 and 1470 m. Hydrothermal venting is strongly inferred from the observation of plumes in sidescan sonar imagery and positive temperature anomalies over the spires and mounds. This field, named the Gondou Field, has a giant mound G1 with a diameter of 280 m and a height of 80 m. Mound G1 has distinctive summit ridges composed of multiple spires where acoustic plumes with temperature anomalies up to 1.12°C are observed, indicative of high-temperature venting. Other than mound G1, a number of active large mounds more than 30 m wide and spires over 10-22 m tall are common and they concentrate in the central and southern areas of the field, suggesting that these areas are the center of present hydrothermal activity. Acoustic plumes imaged by side-scan sonar at the Gondou Field are different in character from bubble plumes imaged in other hydrothermal fields in the Ryukyu Arc. The plumes are diffused and deflected as they rise through the water column and have a shape consistent with black smokers.

Zeta-Proteobacteria dominate the formation of microbial mats in low-temperature hydrothermal vents at Loihi Seamount

NASA Astrophysics Data System (ADS)

Rassa, A. C.; McAllister, S. M.; Safran, S. A.; Moyer, C. L.

2007-12-01

Loihi Seamount is Hawaii's youngest volcano and one of the earth's most active. Loihi is located 30 km SE of the big island of Hawaii and rises over 3000m above the sea floor and summits at 1100m below sea level. An eruption in 1996 of Loihi led to the formation of Pele's Pit, a 300 meter deep caldera. The current observations have revealed diffuse hydrothermal venting causing low to intermediate temperatures (10 to 65°C). The elevated temperatures, coupled with high concentrations of Fe(II) (ranging from 50 to 750 μM) support conditions allowing for extensive microbial mat formation. The focus of this study was to identify the colonizing populations of bacteria generated by the microbial mats at Loihi Seamount. Twenty-six microbial growth chambers were deployed and recovered after placement in the flow of hydrothermal vents for 3 to 8 days from within Loihi's caldera. Genomic DNA was extracted from samples and analyzed by Terminal-Restriction Fragment Length Polymorphism (T-RFLP) using eight restriction enzyme treatments to generate fingerprints from bacterial amplicons of small subunit rRNA genes (SSU rDNAs). Pearson product-moment coupled with UPGMA cluster analysis of these T-RFLP fingerprints showed that these communities bifurcated into two primary clusters. The first (Group 1) had an average vent effluent temperature of 44°C, and the second (Group 2) had an average vent effluent temperature of 64°C. Representative samples from within the two clusters (or groups) were chosen for further clone library and sequencing analysis. These libraries revealing a dominance of the recently discovered zeta- Proteobacteria in the lower temperature group (Group 1) indicating that they were the dominant colonizers of the microbial mats. These microaerophilic, obligately lithotrophic, Fe-oxidizing bacteria are most closely related to Mariprofundus ferrooxydans. The higher temperature group (Group 2) was dominated by epsilon- Proteobacteria primarily of the genus Sulfurimonas, which are sulfur- and thiosulfate-oxidizing bacteria.

On the early fate of hydrothermal iron at deep-sea vents: A reassessment after in situ filtration

NASA Astrophysics Data System (ADS)

Waeles, M.; Cotte, L.; Pernet-Coudrier, B.; Chavagnac, V.; Cathalot, C.; Leleu, T.; Laës-Huon, A.; Perhirin, A.; Riso, R. D.; Sarradin, P.-M.

2017-05-01

Deep-sea hydrothermal venting is now recognized as a major source of iron (Fe), an essential trace element that controls marine productivity. However, the reactions occurring during dispersal from buoyant plumes to neutrally buoyant hydrothermal plumes are still poorly constrained. Here we report for the first time on the dissolved-particulate partition of Fe after in situ filtration at the early stage of mixing at different hydrothermal discharges, i.e., Lucky Strike (37°N), TAG (26°N), and Snakepit (23°N) on the Mid-Atlantic Ridge. We found that hydrothermal iron is almost completely preserved (>90%) in the dissolved fraction, arguing for low iron-bearing sulfide precipitation of iron in basalt-hosted systems with low Fe:H2S ratios. This result can only be explained by a kinetically limited formation of pyrite. The small part of Fe being precipitated as sulfides in the mixing gradient (<10%) is restricted to the inclusion of Fe in minerals of high Cu and Zn content. We also show that secondary venting is a source of Fe-depleted hydrothermal solutions. These results provide new constrains on Fe fluxes from hydrothermal venting.

[Diversity of culturable sulfur-oxidizing bacteria in deep-sea hydrothermal vent environments of the South Atlantic].

PubMed

Xu, Hongxiu; Jiang, Lijing; Li, Shaoneng; Zhong, Tianhua; Lai, Qiliang; Shao, Zongze

2016-01-04

To investigate the diversity of culturable sulfur-oxidizing bacteria in hydrothermal vent environments of the South Atlantic, and analyze their characteristics of sulfur oxidation. We enriched and isolated sulfur-oxidizing bacteria from hydrothermal vent samples collected from the South Atlantic. The microbial diversity in enrichment cultures was analyzed using the Denatural Gradient Gel Electrophoresis method. Sulfur-oxidizing characteristics of the isolates was further studied by using ion chromatography. A total of 48 isolates were obtained from the deep-sea hydrothermal vent samples, which belonged to 23 genera and mainly grouped into alpha-Proteobacteria (58.3%), Actinobacteria (22.9%) and gama-Proteobacteria (18.8%). Among them, the genus Thalassospira, Martelella and Microbacterium were dominant. About 60% of the isolates exibited sulfur-oxidizing ability and strain L6M1-5 had a higher sulfur oxidation rate by comparison analysis. The diversity of sulfur-oxidizing bacteria in hydrothermal environments of the South Atlantic was reported for the first time based on culture-dependent methods. The result will help understand the biogechemical process of sulfur compounds in the deep-sea hydrothermal environments.

Variations in deep-sea hydrothermal vent communities on the Mid-Atlantic Ridge near the Azores plateau

NASA Astrophysics Data System (ADS)

Desbruyères, D.; Biscoito, M.; Caprais, J.-C.; Colaço, A.; Comtet, T.; Crassous, P.; Fouquet, Y.; Khripounoff, A.; Le Bris, N.; Olu, K.; Riso, R.; Sarradin, P.-M.; Segonzac, M.; Vangriesheim, A.

2001-05-01

Near the Azores Triple Junction as the Azores Plateau is approached, the ridge axis becomes shallower; its depth decreases from ca. 2400 m in the R AINBOW vent field (36°13'N) to ca. 850 m in the M ENEZ G WEN vent field (37°35'N). In this area, extensive mussel beds of the mytilid Bathymodiolus azoricus dominate the hydrothermal vent fauna, along with populations of three shrimps ( Rimicaris exoculata, Mirocaris fortunata and Chorocaris chacei). The main physical and chemical characteristics of the vent habitat were studied by discrete sampling, in situ analysis and sediment trap moorings. The vent fauna is distributed along a variable band where the vent fluids and seawater mix, with R. exoculata living in the most concentrated areas and Bathymodiolus azoricus in the most diluted zones. Various non-endemic species live at the border of the vent field. The variations observed in structure and composition of the communities along the depth gradient are most likely due to changes in vent fluid toxicity (metallic and sulphide content) and suspended mineral particles, which render the fluids harsher for species living there. The main faunal differences observed between L UCKY S TRIKE and M ENEZ G WEN hydrothermal fields are due to an impoverishment in the hydrothermal endemic species and to the penetration of bathyal species. The comparison of the three studied vent fields suggests the existence of a succession of several biogeographic islands rather than a single province.

Ultra-diffuse hydrothermal venting supports Fe-oxidizing bacteria and massive umber deposition at 5000 m off Hawaii

PubMed Central

Edwards, Katrina J; Glazer, B T; Rouxel, O J; Bach, W; Emerson, D; Davis, R E; Toner, B M; Chan, C S; Tebo, B M; Staudigel, H; Moyer, C L

2011-01-01

A novel hydrothermal field has been discovered at the base of Lōihi Seamount, Hawaii, at 5000 mbsl. Geochemical analyses demonstrate that ‘FeMO Deep', while only 0.2 °C above ambient seawater temperature, derives from a distal, ultra-diffuse hydrothermal source. FeMO Deep is expressed as regional seafloor seepage of gelatinous iron- and silica-rich deposits, pooling between and over basalt pillows, in places over a meter thick. The system is capped by mm to cm thick hydrothermally derived iron-oxyhydroxide- and manganese-oxide-layered crusts. We use molecular analyses (16S rDNA-based) of extant communities combined with fluorescent in situ hybridizations to demonstrate that FeMO Deep deposits contain living iron-oxidizing Zetaproteobacteria related to the recently isolated strain Mariprofundus ferroxydans. Bioenergetic calculations, based on in-situ electrochemical measurements and cell counts, indicate that reactions between iron and oxygen are important in supporting chemosynthesis in the mats, which we infer forms a trophic base of the mat ecosystem. We suggest that the biogenic FeMO Deep hydrothermal deposit represents a modern analog for one class of geological iron deposits known as ‘umbers' (for example, Troodos ophilolites, Cyprus) because of striking similarities in size, setting and internal structures. PMID:21544100

From Geochemistry to Biochemistry: Simulating Prebiotic Chemistry Driven by Geochemical Gradients in Alkaline Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Barge, Laurie

2016-07-01

Planetary water-rock interfaces generate energy in the form of redox, pH, and thermal gradients, and these disequilibria are particularly focused in hydrothermal vent systems where the reducing, heated hydrothermal fluid feeds back into the more oxidizing ocean. Alkaline hydrothermal vents have been proposed as a likely location for the origin of life on the early Earth due to various factors: including the hydrothermal pH / Eh gradients that resemble the ubiquitous electrical / proton gradients in biology, the catalytic hydrothermal precipitates that resemble inorganic catalysts in enzymes, and the presence of electron donors and acceptors in hydrothermal systems (e.g. H2 + CH4 and CO2) that are thought to have been utilized in the earliest metabolisms. Of particular importance for the emergence of metabolism are the mineral "chimneys" that precipitate at the vent fluid / seawater interface. Hydrothermal chimneys are flow-through chemical reactors that form porous and permeable inorganic membranes transecting geochemical gradients; in some ways similar to biological membranes that transect proton / ion gradients and harness these disequilibria to drive metabolism. These emergent chimney structures in the far-from-equilibrium system of the alkaline vent have many properties of interest to the origin of life that can be simulated in the laboratory: for example, they can generate electrical energy and drive redox reactions, and produce catalytic minerals (in particular the metal sulfides and iron oxyhydroxides - "green rust") that can facilitate chemical reactions towards proto-metabolic cycles and biosynthesis. Many of the factors prompting interest in alkaline hydrothermal vents on Earth may also have been present on early Mars, or even presently within icy worlds such as Europa or Enceladus - thus, understanding the disequilibria and resulting prebiotic chemistry in these systems can be of great use in assessing the potential for other environments in the Solar System where life could have emerged.

Newly Discovered Hydrothermal Plumes Along the Furious Fifties, South East Indian Ridge (SEIR; 128°E-140°E)

NASA Astrophysics Data System (ADS)

Boulart, C.; Chavagnac, V.; Briais, A.; Revillon, S.; Donval, J. P.; Guyader, V.

2015-12-01

We report on the first evidence for hydrothermal activity along the intermediate-spreading South-East Indian Ridge (SEIR) between Australia and Antarctica (128°E-140°E), discovered during the STORM cruise of R/V L'Atalante. This section of the SEIR is located east of the low-magma Australian-Antarctic Discordance (AAD), where the ridge has the morphology of a slow-spreading mid-ocean ridge despite its intermediate spreading rate of 75 mm/yr. The axial depth decreases eastward, reflecting an eastward increase in magma budget.Using in-situ geochemical tracers based on optical backscatter, temperature, redox potential sensor and in situ mass spectrometer (ISMS) anomalies, we establish the existence of several distinct hydrothermal plumes within the water column along the 500 nautical miles ridge section. At one site, the combination of near-bottom temperature anomalies of 0.1°C together with strong dissolved methane and dissolved carbon dioxide anomalies revealed by the ISMS provides the precise location of an active vent in the Deep Southern Indian Ocean off Tasmania. Hydrothermal venting along the 128°E-140°E section of the SEIR appears to be significant, an observation consistent with the global link between spreading rate and plume occurrence (Baker and German, 2004). Moreover, the plume incidence increases westward and, in the eastern part, hydrothermal venting seems to be less significant, suggesting a possible influence of the high magma budget, as observed in mid-ocean ridge sections affected by hotspots. Future investigation will focus on the direct identification of venting sources and the study of hydrothermal circulation within the specific settings of the AAD. The observation of new venting sites at the frontier between Pacific and Indian Oceans may also provide new insights on the biogeography (diversity and distribution) of hydrothermal fauna. Baker, E. T., and C. R. German (2004), On the global distribution of hydrothermal vent fields, in Mid-Ocean Ridges: Hydrothermal Interactions

Evidence for early life in Earth's oldest hydrothermal vent precipitates.

PubMed

Dodd, Matthew S; Papineau, Dominic; Grenne, Tor; Slack, John F; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T S

2017-03-01

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite-haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

Evidence for early life in Earth’s oldest hydrothermal vent precipitates

USGS Publications Warehouse

Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; Slack, John F.; Rittner, Martin; Pirajno, Franco; O’Neil, Jonathan; Little, Crispin T.S.

2017-01-01

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

Direct observation of the evolution of a seafloor 'black smoker' from vapor to brine

USGS Publications Warehouse

Von Damm, Karen L.; Buttermore, L.G.; Oosting, S.E.; Bray, A.M.; Fornari, D.J.; Lilley, M.D.; Shanks, Wayne C.

1997-01-01

A single hydrothermal vent, 'F' vent, occurring on very young crust at 9??16.8???N, East Pacific Rise, was sampled in 1991 and 1994. In 1991, at the measured temperature of 388??C and seafloor pressure of 258 bar, the fluids from this vent were on the two-phase curve for seawater. These fluids were very low in chlorinity and other dissolved species, and high in gases compared to seawater and most sampled seafloor hydrothermal vent fluids. In 1994, when this vent was next sampled, it had cooled to 351??C and was venting fluids ???1.5 times seawater chlorinity. This is the first reported example of a single seafloor hydrothermal vent evolving from vapor to brine. The 1991 and 1994 fluids sampled from this vent are compositionally conjugate pairs to one another. These results support the hypothesis that vapor-phase fluids vent in the early period following a volcanic eruption, and that the liquid-phase brines are stored within the oceanic crust, and vent at a later time, in this case 3 years. These results demonstrate that the venting of brines can occur in the same location, in fact from the same sulfide edifice, where the vapor-phase fluids vented previously.

Extensive hydrothermal activity in the NE Lau basin revealed by ROV dives

NASA Astrophysics Data System (ADS)

Embley, R. W.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E. J.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N. J.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Kenner-Chavis, P.; Martinez-Lyons, A.; Sheehan, C.; Brian, R.

2014-12-01

Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine hydrothermal sites in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These sites, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing site on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/hydrothermal activity in the NE Lau Basin. Chemosynthetic ecosystems at these sites range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing sites to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the hydrothermal systems in this area provides an intriguing template to study the interaction of hydrothermal fluid chemistry, chemosynthetic habitats and their geologic underpinning within an arc/backarc setting.

Hyperactive hydrothermal activity in the NE Lau basin revealed by ROV dives

NASA Astrophysics Data System (ADS)

Embley, R. W.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Keener, P.; Martinez Lyons, A.; Sheehan, C.; Brian, R.

2013-12-01

Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine hydrothermal sites in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These sites, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing site on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/hydrothermal activity in the NE Lau Basin. Chemosynthetic ecosystems at these sites range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing sites to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the hydrothermal systems in this area provides an intriguing template to study the interaction of hydrothermal fluid chemistry, chemosynthetic habitats and their geologic underpinning within an arc/backarc setting.

An abyssal mobilome: viruses, plasmids and vesicles from deep-sea hydrothermal vents.

PubMed

Lossouarn, Julien; Dupont, Samuel; Gorlas, Aurore; Mercier, Coraline; Bienvenu, Nadege; Marguet, Evelyne; Forterre, Patrick; Geslin, Claire

2015-12-01

Mobile genetic elements (MGEs) such as viruses, plasmids, vesicles, gene transfer agents (GTAs), transposons and transpovirions, which collectively represent the mobilome, interact with cellular organisms from all three domains of life, including those thriving in the most extreme environments. While efforts have been made to better understand deep-sea vent microbial ecology, our knowledge of the mobilome associated with prokaryotes inhabiting deep-sea hydrothermal vents remains limited. Here we focus on the abyssal mobilome by reviewing accumulating data on viruses, plasmids and vesicles associated with thermophilic and hyperthermophilic Bacteria and Archaea present in deep-sea hydrothermal vents. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Google Earth locations of USA and seafloor hydrothermal vents with associated rare earth element data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrew Fowler

Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal vents that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal Vents" and "Rare earth element content of thermal fluids from Surprise Valley, California"

Unveiling the transformation and bioavailability of dissolved organic matter in contrasting hydrothermal vents using fluorescence EEM-PARAFAC.

PubMed

Yang, Liyang; Zhuang, Wan-E; Chen, Chen-Tung Arthur; Wang, Bing-Jye; Kuo, Fu-Wen

2017-03-15

The submarine hydrothermal systems are extreme environments where active cycling of dissolved organic matter (DOM) may occur. However, little is known about the optical properties and bioavailability of hydrothermal DOM, which could provide valuable insights into its transformation processes and biogeochemical reactivity. The quantity, quality, and bioavailability of DOM were investigated for four very different hydrothermal vents east of Taiwan, using dissolved organic carbon (DOC), absorption spectroscopy, and fluorescence excitation-emission matrices-parallel factor analysis (EEM-PARAFAC). The DOC and absorption coefficient a 280 were both lower in the two hydrothermal vents off the Orchid Island and on the Green Island than in the surrounding seawater and the two vents off the Kueishantao Island, indicating effective removals of DOM in the former two hydrothermal systems owing to possible adsorption/co-precipitation and thermal degradation respectively. The four hydrothermal DOM showed notable differences in the absorption spectral slope S 275-295 , humification index HIX, biological index BIX, EEM spectra, and the relative distributions of seven PARAFAC components. The results demonstrated a high diversity of chemical composition and transformation history of DOM under contrasting hydrothermal conditions. The little change in the hydrothermal DOC after 28-day microbial incubations indicated a low bioavailability of the bulk DOM, and different PARAFAC components showed contrasting bioavailability. The results have profound implications for understanding the biogeochemical cycling and environmental effects of hydrothermal DOM in the marine environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

New insights on the remarkable longevity of hydrothermal plumes over the Cleft segment of the Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Jellinek, M.; Carazzo, G.

2011-12-01

Observations of the temporal variability of hydrothermal activity over the Juan de Fuca Ridge provide valuable clues for understanding the dynamics of hydrothermal plumes in the deep ocean. Analyses of hydrothermal temperature and light attenuation anomalies show that the structure of these plumes varies on an interannual rather than weekly or monthly time scale. This surprising stability is in complete disagreement with calculations of the residence time for the suspended particles, which suggest a complete particle sedimentation within a few days or weeks. In order to understand this difference, we performed analog experiments simulating particle-laden hydrothermal plumes. These experiments consist in injecting upwards at a fixed rate a hot mixture of fresh water and solid particles in a tank containing stratified salt water. Measurements of light attenuation, temperature and salinity anomalies are conducted during the experiments in order to decipher the causal links between real-time observations and venting conditions. Our results show that depending on the source conditions and the strength of density stratification in the tank, large-scale instabilities may develop due to the differential diffusion of heat and fine particles. Diffusive particle convection enhances the dispersion of fine particles and increases the longevity of the plume. We show that this process is a common phenomenon in natural submarine plumes, which not only increases the longevity of the plumes up to at least 5 years, but also permits dissolution processes to occur providing large amounts of dissolved chemical species far from the point of emission. A new model for particle sedimentation from hydrothermal plumes is presented and tested against natural data collected over the Cleft segment of the Juan de Fuca Ridge between 1987 and 1991. This model is found to be in good agreement with measurements of the rate of change of light attenuation within the chronic plume overlying the north Cleft vent field. We find that this particular plume remained in suspension for 6.5 years but became undetectable after 5 years in good agreement with observations.

A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents

USGS Publications Warehouse

Reysenbach, A.-L.; Liu, Yajing; Banta, A.B.; Beveridge, T.J.; Kirshtein, J.D.; Schouten, S.; Tivey, M.K.; Von Damm, Karen L.; Voytek, M.A.

2006-01-01

Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75??C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents. ?? 2006 Nature Publishing Group.

Organic matter in hydrothermal metal ores and hydrothermal fluids

USGS Publications Warehouse

Orem, W.H.; Spiker, E. C.; Kotra, R.K.

1990-01-01

Massive polymetallic sulfides are currently being deposited around active submarine hydrothermal vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine hydrothermal activity. Thus, there is a significant potential for organic matter/metal interactions in these systems. We have studied modern and ancient hydrothermal metal ores and modern hydrothermal fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient hydrothermal systems were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered hydrothermal systems had higher organic C values than those from modern and ancient hydrothermal systems lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in hydrothermal metal ores from sediment covered vents probably arises from complex sedimentary organic matter by hydrothermal pyrolysis. The dissolved organic C concentrations of hydrothermal fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from hydrothermal fluids by biological activity or by co-precipitation with metal ores. ?? 1990.

Constraints on hydrocarbon and organic acid abundances in hydrothermal fluids at the Von Damm vent field, Mid-Cayman Rise (Invited)

NASA Astrophysics Data System (ADS)

McDermott, J. M.; Seewald, J.; German, C. R.; Sylva, S. P.

2013-12-01

The generation of organic compounds in vent fluids has been of interest since the discovery of seafloor hydrothermal systems, due to implications for the sustenance of present-day microbial populations and their potential role in the origin of life on early Earth. Possible sources of organic compounds in hydrothermal systems include microbial production, thermogenic degradation of organic material, and abiotic synthesis. Abiotic organic synthesis reactions may occur during active circulation of seawater-derived fluids through the oceanic crust or within olivine-hosted fluid inclusions containing carbon-rich magmatic volatiles. H2-rich end-member fluids at the Von Damm vent field on the Mid-Cayman Rise, where fluid temperatures reach 226°C, provide an exciting opportunity to examine the extent of abiotic carbon transformations in a highly reducing system. Our results indicate multiple sources of carbon compounds in vent fluids at Von Damm. An ultramafic-influenced hydrothermal system located on the Mount Dent oceanic core complex at 2350 m depth, Von Damm vent fluids contain H2, CH4, and C2+ hydrocarbons in high abundance relative to basalt-hosted vent fields, and in similar abundance to other ultramafic-hosted systems, such as Rainbow and Lost City. The CO2 content and isotopic composition in end-member fluids are virtually identical to bottom seawater, suggesting that seawater DIC is unchanged during hydrothermal circulation of seawater-derived fluids. Accordingly, end-member CH4 that is present in slightly greater abundance than CO2 cannot be generated from reduction of aqueous CO2 during hydrothermal circulation. We postulate that CH4 and C2+ hydrocarbons that are abundantly present in Von Damm vent fluids reflect leaching of fluids from carbon- and H2-rich fluid inclusions hosted in plutonic rocks. Geochemical modeling of carbon speciation in the Von Damm fluids suggests that the relative abundances of CH4, C2+ hydrocarbons, and CO2 are consistent with thermodynamic equilibrium at higher temperatures and more reducing conditions than those observed in the Von Damm vent fluids. These findings are consistent with a scenario in which n-alkanes form abiotically within a high-H2, carbon-rich olivine-hosted fluid inclusion, and are subsequently liberated and transported to the seafloor during hydrothermal alteration of the lower crustal rocks exposed at the Mount Dent oceanic core complex. Mixed fluids at Von Damm show depletions in CO2 and H2, relative to conservative mixing. Multiple S isotope measurements indicate that the H2 sink cannot be attributed to sulfate reduction. Thermodynamic constraints indicate that high-H2 conditions support the active formation of formate via reduction of dissolved CO2 during hydrothermal circulation - a process that has also been described at the Lost City vent field - and could account for the concurrent depletions in CO2 and H2. The transformation of inorganic carbon to organic compounds via two distinct pathways in modern seafloor hydrothermal vents validates theoretical and experimental conceptual models regarding processes occurring in the crust and during hydrothermal circulation, and is relevant to supporting life in vent ecosystems.

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H2 and CO2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents.

PubMed

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H 2 and CO 2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

High-Resolution Photo-Mosaicing of the Rosebud Hydrothermal Vent Site and Surrounding Lava Flows, Galapagos Rift 86W: Techniques and Interpretations

NASA Astrophysics Data System (ADS)

Rzhanov, Y.; Mayer, L.; Fornari, D.; Shank, T.; Humphris, S.; Scheirer, D.; Kinsey, J.; Whitcomb, L.

2003-12-01

The Rosebud hydrothermal vent field was discovered in May 2002 in the Galapagos Rift near 86W during a series of Alvin dives and ABE autonomous vehicle surveys. Vertical-incidence digital imaging using a 3.1 Mpixel digital camera and strobe illumination from altitudes of 3-5m was carried out during the Alvin dives. A complete survey of the Rosebud vent site was carried out on Alvin Dive 3790. Submersible position was determined by post-cruise integration of 1.2 MHz bottom-lock Doppler sonar velocity data logged at 5Hz, integrated with heading and attitude data from a north-seeking fiber-optic gyroscope logged at 10Hz, and initialized with a surveyed-in long-baseline transponder navigation system providing geodetic position fixes at 15s intervals. The photo-mosaicing process consisted of three main stages: pre-processing, pair-wise image co-registration, and global alignment. Excellent image quality allowed us to avoid lens distortion correction, so images only underwent histogram equalization. Pair-wise co-registration of sequential frames was done partially automatically (where overlap exceeded 70 percent we employed a frequency-domain based technique), and partially manually (when overlap did not exceed 15 percent and manual feature extraction was the only way to find transformations relating the frames). Partial mosaics allowed us to determine which non-sequential frames had substantial overlap, and the corresponding transformations were found via feature extraction. Global alignment of the images consisted of construction of a sparse, nonlinear over-constrained system of equations reflecting positions of the frames in real-world coordinates. This system was solved using least squares, and the solution provided globally optimal positions of the frames in the overall mosaic. Over 700 images were mosaiced resulting in resolution of ~3 mm per pixel. The mosaiced area covers approximately 50 m x 60 m and clearly shows several biological zonations and distribution of lava flow morphologies, including what is interpreted as the contact between older lobate lava and the young sheet flow that hosts Rosebud vent communities. Recruitment of tubeworms, mussels, and clams is actively occurring at more than five locations oriented on a NE-SW trend where vent emissions occur through small cracks in the sheet flow. Large-scale views of seafloor hydrothermal vent sites, such as the one produced for Rosebud, are critical to properly understanding spatial relationships between hydrothermal biological communities, sites of focused and diffuse fluid flow, and the complex array of volcanic and tectonic features at mid-ocean ridge crests. These high-resolution perspectives are also critical to time-series studies where quantitative documentation of changes can be related to variations in hydrothermal, magmatic and tectonic processes.

First Discovery and Investigation of a High-Temperature Hydrothermal Vent Field on the Ultra- Slow Spreading Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Tao, C.; Lin, J.; Guo, S.; Chen, Y. J.; Wu, G.; Han, X.; German, C. R.; Yoerger, D. R.; Zhu, J.; Zhou, N.; Su, X.; Baker, E. T.; Party, S.

2007-12-01

Two recent cruises on board the Chinese research vessel Dayang Yihao have successfully investigated the first active hydrothermal vent field to be located along the ultraslow spreading Southwest Indian Ridge (SWIR) and collected hydrothermal sulfide deposit samples. The newly discovered hydrothermal vent field is located on the western end of a magmatically robust spreading segment immediately west of the Gallieni transform fault. Preliminary evidence of strong turbidity anomalies was first measured during a Nov. 2005 cruise on board Dayang Yihao (InterRidge News, vol. 15, pp. 33-34, 2006). Color video footages of the seafloor in the vent-field area were first obtained by a deep-towed video camera in February 2007 during DY115-19 Leg 1, when significant water column turbidity anomalies, noticeable temperature anomalies and methane anomalies were also measured. The vent field was then precisely located, mapped, and photographed in great detail in February- March 2007 during the DY115-19 Leg 2, using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution. A high-resolution bathymetric map, more than 5,000 near-bottom color photos, and several types of water column data were all obtained during three phases of ABE dives. Within the approximately 120-m-long by 100-m-wide hydrothermal field, three groups of active high-temperature vents were identified and color images of black smokers and associated biological communities were obtained from ABE, flying 5 m above the seafloor. Hydrothermal sulfide deposits were then successfully obtained using a TV-guided grab.

First Discovery and Investigation of a High-Temperature Hydrothermal Vent Field on the Ultra- Slow Spreading Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Tao, C.; Lin, J.; Guo, S.; Chen, Y. J.; Wu, G.; Han, X.; German, C. R.; Yoerger, D. R.; Zhu, J.; Zhou, N.; Su, X.; Baker, E. T.; Party, S.

2004-12-01

Two recent cruises on board the Chinese research vessel Dayang Yihao have successfully investigated the first active hydrothermal vent field to be located along the ultraslow spreading Southwest Indian Ridge (SWIR) and collected hydrothermal sulfide deposit samples. The newly discovered hydrothermal vent field is located on the western end of a magmatically robust spreading segment immediately west of the Gallieni transform fault. Preliminary evidence of strong turbidity anomalies was first measured during a Nov. 2005 cruise on board Dayang Yihao (InterRidge News, vol. 15, pp. 33-34, 2006). Color video footages of the seafloor in the vent-field area were first obtained by a deep-towed video camera in February 2007 during DY115-19 Leg 1, when significant water column turbidity anomalies, noticeable temperature anomalies and methane anomalies were also measured. The vent field was then precisely located, mapped, and photographed in great detail in February- March 2007 during the DY115-19 Leg 2, using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution. A high-resolution bathymetric map, more than 5,000 near-bottom color photos, and several types of water column data were all obtained during three phases of ABE dives. Within the approximately 120-m-long by 100-m-wide hydrothermal field, three groups of active high-temperature vents were identified and color images of black smokers and associated biological communities were obtained from ABE, flying 5 m above the seafloor. Hydrothermal sulfide deposits were then successfully obtained using a TV-guided grab.

Using Image Analysis to Explore Changes In Bacterial Mat Coverage at the Base of a Hydrothermal Vent within the Caldera of Axial Seamount

NASA Astrophysics Data System (ADS)

Knuth, F.; Crone, T. J.; Marburg, A.

2017-12-01

The Ocean Observatories Initiative's (OOI) Cabled Array is delivering real-time high-definition video data from an HD video camera (CAMHD), installed at the Mushroom hydrothermal vent in the ASHES hydrothermal vent field within the caldera of Axial Seamount, an active submarine volcano located approximately 450 kilometers off the coast of Washington at a depth of 1,542 m. Every three hours the camera pans, zooms and focuses in on nine distinct scenes of scientific interest across the vent, producing 14-minute-long videos during each run. This standardized video sampling routine enables scientists to programmatically analyze the content of the video using automated image analysis techniques. Each scene-specific time series dataset can service a wide range of scientific investigations, including the estimation of bacterial flux into the system by quantifying chemosynthetic bacterial clusters (floc) present in the water column, relating periodicity in hydrothermal vent fluid flow to earth tides, measuring vent chimney growth in response to changing hydrothermal fluid flow rates, or mapping the patterns of fauna colonization, distribution and composition across the vent over time. We are currently investigating the seventh scene in the sampling routine, focused on the bacterial mat covering the seafloor at the base of the vent. We quantify the change in bacterial mat coverage over time using image analysis techniques, and examine the relationship between mat coverage, fluid flow processes, episodic chimney collapse events, and other processes observed by Cabled Array instrumentation. This analysis is being conducted using cloud-enabled computer vision processing techniques, programmatic image analysis, and time-lapse video data collected over the course of the first CAMHD deployment, from November 2015 to July 2016.

An Approach to Mimicking Abiotic Hydrogenation of Carbon Dioxide in Alkaline Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Wade, L. A.; Fraser, S.; Haile, S.; Collier, P.

2010-04-01

A microfludic approach is considered to determine whether the natural proton-motive and chemiosmotic forces seen in alkaline hydrothermal vents were purely coincidental or if they had a real bearing on how life emerged.

Genome-resolved metagenomics reveals that sulfur metabolism dominates the microbial ecology of rising hydrothermal plumes

NASA Astrophysics Data System (ADS)

Anantharaman, K.; Breier, J. A., Jr.; Jain, S.; Reed, D. C.; Dick, G.

2015-12-01

Deep-sea hydrothermal plumes occur when hot fluids from hydrothermal vents replete with chemically reduced elements and compounds like sulfide, methane, hydrogen, ammonia, iron and manganese mix with cold, oxic seawater. Chemosynthetic microbes use these reduced chemicals to power primary production and are pervasive throughout the deep sea, even at sites far removed from hydrothermal vents. Although neutrally-buoyant hydrothermal plumes have been well-studied, rising hydrothermal plumes have received little attention even though they represent an important interface in the deep-sea where microbial metabolism and particle formation processes control the transformation of important elements and impact global biogeochemical cycles. In this study, we used genome-resolved metagenomic analyses and thermodynamic-bioenergetic modeling to study the microbial ecology of rising hydrothermal plumes at five different hydrothermal vents spanning a range of geochemical gradients at the Eastern Lau Spreading Center (ELSC) in the Western Pacific Ocean. Our analyses show that differences in the geochemistry of hydrothermal vents do not manifest in microbial diversity and community composition, both of which display only minor variance across ELSC hydrothermal plumes. Microbial metabolism is dominated by oxidation of reduced sulfur species and supports a diversity of bacteria, archaea and viruses that provide intriguing insights into metabolic plasticity and virus-mediated horizontal gene transfer in the microbial community. The manifestation of sulfur oxidation genes in hydrogen and methane oxidizing organisms hints at metabolic opportunism in deep-sea microbes that would enable them to respond to varying redox conditions in hydrothermal plumes. Finally, we infer that the abundance, diversity and metabolic versatility of microbes associated with sulfur oxidation impart functional redundancy that could allow it to persist in the dynamic settings of hydrothermal plumes.

Sulfate Reduction and Sulfide Biomineralization By Deep-Sea Hydrothermal Vent Microorganisms

NASA Astrophysics Data System (ADS)

Picard, A.; Gartman, A.; Clarke, D. R.; Girguis, P. R.

2014-12-01

Deep-sea hydrothermal vents are characterized by steep temperature and chemical gradients and moderate pressures. At these sites, mesophilic sulfate-reducing bacteria thrive, however their significance for the formation of sulfide minerals is unknown. In this study we investigated sulfate reduction and sulfide biomineralization by the deep-sea bacterium Desulfovibrio hydrothermalis isolated from a deep-sea vent chimney at the Grandbonum vent site (13°N, East Pacific Rise, 2600 m water depth) [1]. Sulfate reduction rates were determined as a function of pressure and temperature. Biomineralization of sulfide minerals in the presence of various metal concentrations was characterized using light and electron microscopy and optical spectroscopy. We seek to better understand the significance of biological sulfate reduction in deep-sea hydrothermal environments, to characterize the steps in sulfide mineral nucleation and growth, and identify the interactions between cells and minerals. [1] D. Alazard, S. Dukan, A. Urios, F. Verhe, N. Bouabida, F. Morel, P. Thomas, J.L. Garcia and B. Ollivier, Desulfovibrio hydrothermalis sp. nov., a novel sulfate-reducing bacterium isolated from hydrothermal vents, Int. J. Syst. Evol. Microbiol., 53 (2003) 173-178.

Free-living bacterial communities associated with tubeworm (Ridgeia piscesae) aggregations in contrasting diffuse flow hydrothermal vent habitats at the Main Endeavour Field, Juan de Fuca Ridge

PubMed Central

Forget, Nathalie L; Kim Juniper, S

2013-01-01

We systematically studied free-living bacterial diversity within aggregations of the vestimentiferan tubeworm Ridgeia piscesae sampled from two contrasting flow regimes (High Flow and Low Flow) in the Endeavour Hydrothermal Vents Marine Protected Area (MPA) on the Juan de Fuca Ridge (Northeast Pacific). Eight samples of particulate detritus were recovered from paired tubeworm grabs from four vent sites. Most sequences (454 tag and Sanger methods) were affiliated to the Epsilonproteobacteria, and the sulfur-oxidizing genus Sulfurovum was dominant in all samples. Gammaproteobacteria were also detected, mainly in Low Flow sequence libraries, and were affiliated with known methanotrophs and decomposers. The cooccurrence of sulfur reducers from the Deltaproteobacteria and the Epsilonproteobacteria suggests internal sulfur cycling within these habitats. Other phyla detected included Bacteroidetes, Actinobacteria, Chloroflexi, Firmicutes, Planctomycetes, Verrucomicrobia, and Deinococcus–Thermus. Statistically significant relationships between sequence library composition and habitat type suggest a predictable pattern for High Flow and Low Flow environments. Most sequences significantly more represented in High Flow libraries were related to sulfur and hydrogen oxidizers, while mainly heterotrophic groups were more represented in Low Flow libraries. Differences in temperature, available energy for metabolism, and stability between High Flow and Low Flow habitats potentially explain their distinct bacterial communities. PMID:23401293

Hydrothermal plumes along the East Pacific Rise, 8 deg 40 min to 11 deg 50 min N: Plume distribution and relationship to the apparent magmatic budget

NASA Astrophysics Data System (ADS)

Baker, E. T.; Feely, R. A.; Mottl, M. J.; Sansone, F. T.; Wheat, C. G.; Resing, J. A.; Lupton, J. E.

1994-11-01

The interactions between hydrothermal circulation and large-scale geological and geophysical characteristics of the mid-ocean ridge cannot be ascertained without large-scale views of the pattern of hydrothermal venting. Such multi-ridge-segment surveys of venting are accomplished most efficiently by mapping the distribution and intensity of hydrothermal plumes. In November 1991, we mapped hydrothermal temperature (Delta(theta)) and light attenuation (Delta(c)) anomalies above the East Pacific Rise (EPR) continuously from 8 deg 40 min to 11 deg 50 min N, a fast spreading ridge crest portion bisected by the Clipperton Transform Fault. Plume distributions show a precise correlation with the distribution of active vents where video coverage of the axial caldera is exhaustive. Elsewhere in the study area the sketchy knowledge of vent locations gleaned from scattered camera tows predicts only poorly the large-scale hydrothermal pattern revealed by our plume studies. Plumes were most intense between 9 deg 42 min and 9 deg 54 min N, directly over a March/April, 1991, seafloor eruption. These plumes had exceptionally high Delta(c)/Delta(theta) ratios compared to the rest of the study area; we suggest that the phase-separated gas-rich vent fluids discharging here fertilize an abundant population of bacteria. Hydrothermal plume distributions define three categories: intense and continuous, weak and discontinuous and negligible. The location of each category is virtually congruent with areas that are, respectively, magmatically robust, magmatically weak and magmatically starved, as inferred from previous measurements of axial bathymetric undulations, cross-axis inflation and magma chamber depth and continuity. This congruency implies a fine-scale spatial and temporal connection between magmatic fluctuations and hydrothermal venting. We thus speculate that, at least along this fast spreading section of the EPR, cyclic replenishment, eruption and freezing of the thin axial melt lens exerts greater control over hydrothermal venting than the more enduring zones of crystal mush and hot rock. We found intense, and continuous, plumes along 33% of the surveyed ridge crest, an observation implying that any point on the ridge is, on average, hyrothermally active one-third of the time. Combining this result with the 20% plume coverage found along the medium-rate Juan de Fuca Ridge suggests that superfast (approximately 150 mm/yr) spreading rates should support vigorous venting along approximately 50% of their length, if spreading rate and along-axis plume coverage are linearly related.

Experimentally Testing Hydrothermal Vent Origin of Life on Enceladus and Other Icy/Ocean Worlds.

PubMed

Barge, Laura M; White, Lauren M

2017-09-01

We review various laboratory strategies and methods that can be utilized to simulate prebiotic processes and origin of life in hydrothermal vent systems on icy/ocean worlds. Crucial steps that could be simulated in the laboratory include simulations of water-rock chemistry (e.g., serpentinization) to produce hydrothermal fluids, the types of mineral catalysts and energy gradients produced in vent interfaces where hydrothermal fluids interface with the surrounding seawater, and simulations of biologically relevant chemistry in flow-through gradient systems (i.e., far-from-equilibrium experiments). We describe some examples of experimental designs in detail, which are adaptable and could be used to test particular hypotheses about ocean world energetics or mineral/organic chemistry. Enceladus among the ocean worlds provides an ideal test case, since the pressure at the ocean floor is more easily simulated in the lab. Results for Enceladus could be extrapolated with further experiments and modeling to understand other ocean worlds. Key Words: Enceladus-Ocean worlds-Icy worlds-Hydrothermal vent-Iron sulfide-Gradient. Astrobiology 17, 820-833.

Hydrothermal Venting at Hinepuia Submarine Volcano, Kermadec Arc: Understanding Magmatic-Hydrothermal Fluid Chemistry

NASA Astrophysics Data System (ADS)

Stucker, Valerie K.; Walker, Sharon L.; de Ronde, Cornel E. J.; Caratori Tontini, Fabio; Tsuchida, Shinji

2017-10-01

The Hinepuia volcanic center is made up of two distinct edifices aligned northwest to southeast, with an active cone complex in the SE. Hinepuia is one of several active volcanoes in the northern segment of the Kermadec arc. Regional magnetic data show no evidence for large-scale hydrothermal alteration at Hinepuia, yet plume data confirm present-day hydrothermal discharge, suggesting that the hydrothermal system may be too young to have altered the host rocks with respect to measurable changes in magnetic signal. Gravity data are consistent with crustal thinning and shallow mantle under the volcanic center. Following the discovery of hydrothermal plumes over Hinepuia, the submersible Shinkai 6500 was used to explore the SE cone and sample hydrothermal fluids. The chemistry of hydrothermal fluids from submarine arc and backarc volcanoes is typically dominated by water-rock interactions and/or magmatic degassing. Chemical analyses of vent fluids show that Hinepuia does not quite fit either traditional model. Moreover, the Hinepuia samples fall between those typically ascribed to both end-member fluid types when plotted on a K-Mg-SO4 ternary diagram. Due to evidence of strong degassing, abundant native sulfur deposition, and H2S presence, the vent sampled at Hinepuia is ultimately classified as a magmatic-hydrothermal system with a water-rock influence. This vent is releasing water vapor and magmatic volatiles with a notable lack of salinity due to subcritical boiling and phase separation. Magmatic-hydrothermal fluid chemistry appears to be controlled by a combination of gas flux, phase separation processes, and volcano evolution and/or distance from the magma source.

Seafloor Uplift in Middle Valley, Juan de Fuca Ridge: New High-Resolution Pressure Data

NASA Astrophysics Data System (ADS)

Inderbitzen, K. E.; Becker, K.; Davis, E. E.

2011-12-01

Currently, in-situ seafloor and basement pressures are continuously monitored and recorded by an ODP subseafloor hydrogeological observatory (CORK) located in Middle Valley, Juan de Fuca Ridge. Hole 857D was drilled in 1991 in thickly sedimented crust to a depth of 936 mbsf and instrumented with an original CORK that was replaced in 1996. A large hydrothermal field (Dead Dog) lies roughly 1.7 km north of the hole, and two isolated chimneys and several diffuse flow sites are located ~800 meters northeast. The borehole and the vent fields have been visited periodically by submersible/ROV since 1999. Recent results from the CORK at 857D have shown apparent seafloor uplift, supported by depth records from the submersible Alvin. A constant rate of pressure change of ~6 kPa/yr, from its initiation in 2005 to the visit in 2010, has reduced mean seafloor pressure by ~28 kPa, equivalent to nearly 3 meters of head. This uplift rate is several times the typical pre-eruption inflation rates observed at Axial Seamount further south along the Juan de Fuca Ridge. Initially, the apparent uplift at 857D did not seem to have any effect on local high-temperature hydrothermal venting, however recent operations in Middle Valley revealed distinct changes at not only the hydrothermal field to the northeast, but also a shutdown of high-temperature venting to the north of 857D. We will present new data from Middle Valley, including the first year of data collected by a high-resolution pressure data logger deployed at 857D in June, 2010.

The NOAA/PMEL Vents Program - 1983 to 2013: A History of Deep-Sea Volcanic and Hydrothermal Exploration and Research

NASA Astrophysics Data System (ADS)

Hammond, S. R.; Baker, E. T.; Embley, R. W.

2015-12-01

Inspiration for the Vents program arose from two serendipitous events: the discovery of seafloor spreading-center hydrothermal venting on the Galápagos Rift in 1977, and NOAA's deployment of the first US civilian research multibeam bathymetric sonar on the NOAA Ship Surveyor in 1979. Multibeam mapping in the NE Pacific revealed an unprecedented and revolutionary perspective of the Gorda and Juan de Fuca spreading centers, thus stimulating a successful exploration for volcanic and hydrothermal activity at numerous locations along both. After the 1986 discovery of the first "megaplume,", quickly recognized as the water column manifestation of a deep submarine volcanic eruption, the Vents program embarked on a multi-decadal effort to discover and understand local-, regional-, and, ultimately, global-scale physical, chemical, and biological ocean environmental impacts of submarine volcanism and hydrothermal venting. The Vents program made scores of scientific discoveries, many of which owed their success to the program's equally innovative and productive technological prowess. These discoveries were documented in hundreds of peer-reviewed papers by Vents researchers and their colleagues around the world. An emblematic success was the internationally recognized, first-ever detection, location, and study of an active deep volcanic eruption in 1993. To continue the Vents mission and further enhance its effectiveness in marine science and technology innovation, the program was reorganized in 2014 into two distinct, but closely linked, programs: Earth-Oceans Interactions and Acoustics. Both are currently engaged in expeditions and projects that maintain the Vents tradition of pioneering ocean exploration and research.

Examining the Effect of Temperature, Pressure, Seismicity and Diffuse Fluid Flow on Floc Events at Axial Seamount

NASA Astrophysics Data System (ADS)

Rahman, M.; Crone, T. J.; Knuth, F.; Garcia, C.; Soule, D. C.; Fatland, R.

2017-12-01

Flocculation (floc) events are characterized by the ejection of bacterial material, possibly associated with thermophiles originating from warmer sub-seafloor habitats, into the water column. These events are anecdotally linked to magmatic and tectonic processes common in mid-ocean ridge seafloor environments. However, little is known about the relationship between flocculation events and other potentially triggering processes. The Cabled Array at Axial Seamount provides a suite of interdisciplinary real-time datasets to examine system-level processes governing the volcanic marine environment. The eruption at Axial Seamount in 2015 creates an opportunity to study this volcanic system as it evolves post eruption and identify the relationships between the temperature, pressure, seismicity and the biological response. The Diffuse Vent Fluid 3-D Temperature Array (TMPSF), located within the ASHES hydrothermal vent field at Axial Seamount, uses 24 separate sensors to provide a 3-dimensional distribution of diffuse flow temperatures near the Mushroom hydrothermal vent. Preliminary analysis suggests that the temperature signal is strongly influenced by tides observed using the ocean bottom pressure sensors, which may be related to either gradual shifts in tidal currents above the seafloor, or related to subsurface flux. CamHD, also located within the ASHES field, produces high definition video data, which we analyze to identify changes in water column floc concentration. These data streams allow us to examine the controls on the temperature signal and the associated correlations with microbial seafloor processes. We are currently examining the flocculation event identified in Crone (2016) to determine its relationship to changes in seawater temperatures near the seafloor, seismic activity and seafloor pressure. We will use this proxy to examine other CamHD data and determine if subsequent flocculation events have occurred and if they have a similar relationship to local thermal and seismic activity.

Microbial Community Structure of Deep-sea Hydrothermal Vents on the Ultraslow Spreading Southwest Indian Ridge

PubMed Central

Ding, Jian; Zhang, Yu; Wang, Han; Jian, Huahua; Leng, Hao; Xiao, Xiang

2017-01-01

Southwest Indian Ridge (SWIR) is a typical oceanic ultraslow spreading ridge with intensive hydrothermal activities. The microbial communities in hydrothermal fields including primary producers to support the entire ecosystem by utilizing geochemical energy generated from rock-seawater interactions. Here we have examined the microbial community structures on four hydrothermal vents from SWIR, representing distinct characteristics in terms of temperature, pH and metal compositions, by using Illumina sequencing of the 16S small subunit ribosomal RNA (rRNA) genes, to correlate bacterial and archaeal populations with the nature of the vents influenced by ultraslow spreading features. Epsilon-, Gamma-, Alpha-, and Deltaproteobacteria and members of the phylum Bacteroidetes and Planctomycetes, as well as Thaumarchaeota, Woesearchaeota, and Euryarchaeota were dominant in all the samples. Both bacterial and archaeal community structures showed distinguished patterns compared to those in the fast-spreading East Pacific Ridge or the slow-spreading Mid-Atlantic Ridge as previously reported. Furthermore, within SWIR, the microbial communities are highly correlated with the local temperatures. For example, the sulfur-oxidizing bacteria were dominant within bacteria from low-temperature vents, but were not represented as the dominating group recovered from high temperature (over 300°C) venting chimneys in SWIR. Meanwhile, Thaumarchaeota, the ammonium oxidizing archaea, only showed high relative abundance of amplicons in the vents with high-temperature in SWIR. These findings provide insights on the microbial community in ultraslow spreading hydrothermal fields, and therefore assist us in the understanding of geochemical cycling therein. PMID:28659873

A New Deep-Sea Hydrothermal Vent Species of Ostracoda (Crustacea) from the Western Pacific: Implications for Adaptation, Endemism, and Dispersal of Ostracodes in Chemosynthetic Systems.

PubMed

Tanaka, Hayato; Yasuhara, Moriaki

2016-10-01

Deep-sea hydrothermal vent fields are among the most extreme habitats on Earth. Major research interests in these ecosystems have focused on the anomalous macrofauna, which are nourished by chemoautotrophic bacterial endosymbionts. In contrast, the meiofauna is largely overlooked in this chemosynthetic environment. The present study describes a new species, Thomontocypris shimanagai sp. nov. (Crustacea: Ostracoda), which was collected from the surface of colonies of neoverrucid barnacles and paralvinellid worms on the chimneys at the Myojin-sho submarine caldera. This is the first discovery of an ostracode from deep-sea hydrothermal vent environments in the western Pacific region. In addition to the species description, we discuss three aspects: 1) adaptation, 2) endemism, and 3) dispersal strategy of the hydrothermal vent ostracodes. Regarding these aspects, we conclude the following: 1) the new species may feed on sloughed-off tissues, mucus secretions, or fecal pellets of sessile organisms, rather than depend on chemoautotrophic bacteria as symbionts for energy; 2) as has been pointed out by other studies, Thomontocypris does not likely represent a vent-specific genus; however, this new species is considered to be endemic at the species level, as it has not been found outside of the type locality; and 3) this new species may have migrated from adjacent deep-sea chemosynthesis-based habitats, such as hydrothermal vents, with wood falls potentially having acted as stepping stones.

Submarine fissure eruptions and hydrothermal vents on the southern Juan de Fuca Ridge: preliminary observations from the submersible Alvin

USGS Publications Warehouse

Normark, W.R.

1986-01-01

The submersible Alvin was used to investigate 3 active hydrothermal discharge sites along the S Juan de Fuca Ridge in September 1984. The hydrothermal zones occur within a 10-30m-deep, 30-50m-wide cleft marking the center of the axial valley. This cleft is the eruptive locus for the axial valley. The hydrothermal vents coincide with the main eruptive vents along the cleft. Each hydrothermal zone has multiple discharge sites extending as much as 500m along the cleft. Sulfide deposits occur as clusters (15-100m2 area) of small chimneys (= or <2m high) and as individual and clustered fields of large, branched chimneys (= or <10m high). Recovered sulfide samples are predominantly the tops of chimneys and spires and typically contain more than 80% sphalerite and wurtzite with minor pyrrhotite, pyrite, marcasite, isocubanite, chalcopyrite, anhydrite, anhydrite, and amorphous silica. The associated hydrothermal fluids have the highest chlorinity of any reported to date.-Authors

Molecular ecology of hydrothermal vent microbial communities.

PubMed

Jeanthon, C

2000-02-01

The study of the structure and diversity of hydrothermal vent microbial communities has long been restricted to the morphological description of microorganisms and the use of enrichment culture-based techniques. Until recently the identification of the culturable fraction required the isolation of pure cultures followed by testing for multiple physiological and biochemical traits. However, peculiar inhabitants of the hydrothermal ecosystem such as the invertebrate endosymbionts and the dense microbial mat filaments have eluded laboratory cultivation. Substantial progress has been achieved in recent years in techniques for the identification of microorganisms in natural environments. Application of molecular approaches has revealed the existence of unique and previously unrecognized microorganisms. These have provided fresh insight into the ecology, diversity and evolution of mesophilic and thermophilic microbial communities from the deep-sea hydrothermal ecosystem. This review reports the main discoveries made through the introduction of these powerful techniques in the study of deep-sea hydrothermal vent microbiology.

The stability of amino acids at submarine hydrothermal vent temperatures

NASA Technical Reports Server (NTRS)

Bada, Jeffrey L.; Miller, Stanley L.; Zhao, Meixun

1995-01-01

It has been postulated that amino acid stability at hydrothermal vent temperatures is controlled by a metastable thermodynamic equilibrium rather than by kinetics. Experiments reported here demonstrate that the amino acids are irreversibly destroyed by heating at 240 C and that quasi-equilibrium calculations give misleading descriptions of the experimental observations. Equilibrium thermodynamic calculations are not applicable to organic compounds under high-temperature submarine vent conditions.

An authoritative global database for active submarine hydrothermal vent fields

NASA Astrophysics Data System (ADS)

Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.; Maffei, Andrew

2013-11-01

The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.

Can Life Begin on Enceladus? A Perspective from Hydrothermal Chemistry.

PubMed

Deamer, David; Damer, Bruce

2017-09-01

Enceladus is a target of future missions designed to search for existing life or its precursors. Recent flybys of Enceladus by the Cassini probe have confirmed the existence of a long-lived global ocean laced with organic compounds and biologically available nitrogen. This immediately suggests the possibility that life could have begun and may still exist on Enceladus. Here we will compare the properties of two proposed sites for the origin of life on Earth-hydrothermal vents on the ocean floor and hydrothermal volcanic fields at the surface-and ask whether similar conditions could have fostered the origin of life on Enceladus. The answer depends on which of the two sites would be more conducive for the chemical evolution leading to life's origin. A hydrothermal vent origin would allow life to begin in the Enceladus ocean, but if the origin of life requires freshwater hydrothermal pools undergoing wet-dry cycles, the Enceladus ocean could be habitable but lifeless. These arguments also apply directly to Europa and indirectly to early Mars. Key Words: Enceladus-Hydrothermal vents-Hydrothermal fields-Origin of life. Astrobiology 17, 834-839.

Microdistribution of Faunal Assemblages at Deep-Sea Hydrothermal Vents in the Southern Ocean

PubMed Central

Marsh, Leigh; Copley, Jonathan T.; Huvenne, Veerle A. I.; Linse, Katrin; Reid, William D. K.; Rogers, Alex D.; Sweeting, Christopher J.; Tyler, Paul A.

2012-01-01

Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal vents, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered vent fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of vent biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal activity in a vent field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal activity, and a mosaic image of >250 m2 of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from vent sources and peak temperatures. Assemblages closest to vent sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m−2), followed by a peltospiroid gastropod (>1,500 individuals m−2), eolepadid barnacle (>1,500 individuals m−2), and carnivorous actinostolid anemone (>30 individuals m−2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of activity suggests a possible successional sequence for vent fauna in this new biogeographic province. An increase in δ34S values of primary consumers with distance from vent sources, and variation in their δ13C values also indicate possible zonation of nutritional modes of the vent fauna. By using ROV videography to obtain a high-resolution representation of a vent environment over a greater extent than previous studies, these results provide a baseline for determining temporal change and investigations of processes structuring faunal assemblages at Southern Ocean vents. PMID:23144754

Sulfur Metabolizing Microbes Dominate Microbial Communities in Andesite-Hosted Shallow-Sea Hydrothermal Systems

PubMed Central

Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

2012-01-01

To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan’s coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH4) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH4 was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH4 concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan. PMID:22970260

Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

PubMed

Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

2012-01-01

To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

An off-axis hydrothermal vent field near the Mid-Atlantic Ridge at 30 degrees N.

PubMed

Kelley, D S; Karson, J A; Blackman, D K; Früh-Green, G L; Butterfield, D A; Lilley, M D; Olson, E J; Schrenk, M O; Roe, K K; Lebon, G T; Rivizzigno, P

2001-07-12

Evidence is growing that hydrothermal venting occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centres. Here we report the discovery of an extensive hydrothermal field at 30 degrees N near the eastern intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone. The vent field--named 'Lost City'--is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Myr-old crust, nearly 15 km from the spreading axis, and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks. It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys, rather than the sulphide structures typical of 'black smoker' hydrothermal fields. We found that vent fluids are relatively cool (40-75 degrees C) and alkaline (pH 9.0-9.8), supporting dense microbial communities that include anaerobic thermophiles. Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic, Indian and Arctic ridges, these results indicate that a much larger portion of the oceanic crust may support hydrothermal activity and microbial life than previously thought.

Dive report: Alvin dive #1461; September 28, 1984 (JD 272); Plume site, southern Juan de Fuca Rift

USGS Publications Warehouse

Holcomb, R.T.; Kappel, Ellen S.; Ross, Stephanie L.

1987-01-01

Dive 1461 was the seventh of nine dives during a sea-going field program to investigate hydrothermal activity along the crest of the southern Juan de Fuca Ridge. During this dive on the Plume site, ALVIN crossed the western floor of the axial valley and traversed about 300 ra of the rim and floor of the narrow inner cleft. Hydrotherraal vents were observed only along the east wall of the inner cleft, and venting was concentrated in a single area less than 50 ra long near the base of that wall. The principal vents extended up the wall from the floor of the cleft to a height of about 10 m. Deposits of hydrothermal minerals occur as incrustations and chimneys on the floor and wall of the cleft. Associated with the hydrothermal vents is a community of vent organisms dominated by vestimentiferan worms and fluffy materials of uncertain nature. The inner cleft at the Plume Site is about 60 ra wide and 15-30 m deep. It has a simple U-shaped profile north of the active vent area, but to the south it contains at least one high, narrow ridge which converges with the east wall of the cleft at the site of hydrothermal venting. This area was also the site of a volcanic eruption, which occurred sometime earlier. Like many similar but subaerial examples, this eruption was episodic, but the cause of its interruptions is not yet known. The present hydrotherraal activity appears to be a residual effect of that last eruption, and the rate of hydrothermal deposition will probably decline in this area until another eruption occurs.

Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Jamieson, John William; Hannington, Mark D.; Tivey, Margaret K.; Hansteen, Thor; Williamson, Nicole M.-B.; Stewart, Margaret; Fietzke, Jan; Butterfield, David; Frische, Matthias; Allen, Leigh; Cousens, Brian; Langer, Julia

2016-01-01

Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, barite (BaSO4) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which barite precipitates within seafloor hydrothermal vent systems. Petrographic analyses of 22 barite-rich samples show a range of barite crystal morphologies: dendritic and acicular barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87Sr/86Sr of both seawater and hydrothermal fluid, combined with 87Sr/86Sr data from whole rock and laser-ablation ICP-MS analyses of barite crystals indicate that barite precipitates from mixtures containing as low as 17% and as high as 88% hydrothermal fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic barite forms from fluids of less than 40% hydrothermal component and with a saturation index greater than ∼0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of hydrothermal fluid. Fluid inclusions within barite indicate formation temperatures of between ∼120 °C and 240 °C during barite crystallization. The comparison of fluid inclusion formation temperatures to modelled mixing temperatures indicates that conductive cooling of the vent fluid accounts for 60-120 °C reduction in fluid temperature. Strontium zonation within individual barite crystals records fluctuations in the amount of conductive cooling within chimney walls that may result from cyclical oscillations in hydrothermal fluid flux. Barite chemistry and morphology can be used as a reliable indicator for past conditions of mineralization within both extinct seafloor hydrothermal deposits and ancient land-based volcanogenic massive sulfide deposits.

Modeling mid-ocean ridge hydrothermal response to earthquakes, tides, and ocean currents: a case study at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Xu, G.; Bemis, K. G.

2014-12-01

Seafloor hydrothermal systems feature intricate interconnections among oceanic, geological, hydrothermal, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. The multidisciplinary observatory instruments deployed at the Grotto Mound, a major study site of the NEPTUNE observatory, makes it a perfect place to study the response of a seafloor hydrothermal system to geological and oceanic processes. In this study, we use the multidisciplinary datasets recorded by the NEPTUNE Observatory instruments as observational tools to demonstrate two different aspects of the response of hydrothermal activity at the Grotto Mound to geological and oceanic processes. First, we investigate a recent increase in venting temperature and heat flux at Grotto observed by the Benthic and Resistivity Sensors (BARS) and the Cabled Observatory Vent Imaging Sonar (COVIS) respectively. This event started in Mar 2014 and is still evolving by the time of writing this abstract. An initial interpretation in light of the seismic data recorded by a neighboring ocean bottom seismometer on the NEPTUNE observatory suggests the temperature and heat flux increase is probably triggered by local seismic activities. Comparison of the observations with the results of a 1-D mathematical model simulation of hydrothermal sub-seafloor circulation elucidates the potential mechanisms underlying hydrothermal response to local earthquakes. Second, we observe significant tidal oscillations in the venting temperature time series recorded by BARS and the acoustic imaging of hydrothermal plumes by COVIS, which is evidence for hydrothermal response to ocean tides and currents. We interpret the tidal oscillations of venting temperature as a result of tidal loading on a poroelastic medium. We then invoke poroelastic theories to estimate the crustal permeability, a fundamental property of subsurface hydrothermal circulation, from the phase shift of the tidal oscillations of venting temperature relative to ambient ocean tides. These results together shed light on the influences of seismic and oceanic processes on a seafloor hydrothermal system.

Ferrous iron- and ammonium-rich diffuse vents support habitat-specific communities in a shallow hydrothermal field off the Basiluzzo Islet (Aeolian Volcanic Archipelago).

PubMed

Bortoluzzi, G; Romeo, T; La Cono, V; La Spada, G; Smedile, F; Esposito, V; Sabatino, G; Di Bella, M; Canese, S; Scotti, G; Bo, M; Giuliano, L; Jones, D; Golyshin, P N; Yakimov, M M; Andaloro, F

2017-09-01

Ammonium- and Fe(II)-rich fluid flows, known from deep-sea hydrothermal systems, have been extensively studied in the last decades and are considered as sites with high microbial diversity and activity. Their shallow-submarine counterparts, despite their easier accessibility, have so far been under-investigated, and as a consequence, much less is known about microbial communities inhabiting these ecosystems. A field of shallow expulsion of hydrothermal fluids has been discovered at depths of 170-400 meters off the base of the Basiluzzo Islet (Aeolian Volcanic Archipelago, Southern Tyrrhenian Sea). This area consists predominantly of both actively diffusing and inactive 1-3 meters-high structures in the form of vertical pinnacles, steeples and mounds covered by a thick orange to brown crust deposits hosting rich benthic fauna. Integrated morphological, mineralogical, and geochemical analyses revealed that, above all, these crusts are formed by ferrihydrite-type Fe 3+ oxyhydroxides. Two cruises in 2013 allowed us to monitor and sampled this novel ecosystem, certainly interesting in terms of shallow-water iron-rich site. The main objective of this work was to characterize the composition of extant communities of iron microbial mats in relation to the environmental setting and the observed patterns of macrofaunal colonization. We demonstrated that iron-rich deposits contain complex and stratified microbial communities with a high proportion of prokaryotes akin to ammonium- and iron-oxidizing chemoautotrophs, belonging to Thaumarchaeota, Nitrospira, and Zetaproteobacteria. Colonizers of iron-rich mounds, while composed of the common macrobenthic grazers, predators, filter-feeders, and tube-dwellers with no representatives of vent endemic fauna, differed from the surrounding populations. Thus, it is very likely that reduced electron donors (Fe 2+ and NH 4 + ) are important energy sources in supporting primary production in microbial mats, which form a habitat-specific trophic base of the whole Basiluzzo hydrothermal ecosystem, including macrobenthic fauna. © 2017 John Wiley & Sons Ltd.

Influences of the Tonga Subduction Zone on seafloor massive sulfide deposits along the Eastern Lau Spreading Center and Valu Fa Ridge

NASA Astrophysics Data System (ADS)

Evans, Guy N.; Tivey, Margaret K.; Seewald, Jeffrey S.; Wheat, C. Geoff

2017-10-01

This study investigates the morphology, mineralogy, and geochemistry of seafloor massive sulfide (SMS) deposits from six back-arc hydrothermal vent fields along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the context of endmember vent fluid chemistry and proximity to the Tonga Subduction Zone. To complement deposit geochemistry, vent fluid analyses of Cu, Zn, Ba, Pb and H2,(aq) were completed to supplement existing data and enable thermodynamic calculations of mineral saturation states at in situ conditions. Results document southward increases in the abundance of mantle-incompatible elements in hydrothermal fluids (Ba and Pb) and SMS deposits (Ba, Pb, As, and Sb), which is also expressed in the abundance of barite (BaSO4) and galena (PbS) in SMS deposits. These increases correspond to a decrease in distance between the ELSC/VFR and the Tonga Subduction Zone that correlates with a change in crustal lithology from back-arc basin basalt in the north to mixed andesite, rhyolite, and dacite in the south. Barite influences deposit morphology, contributing to the formation of horizontal flanges and squat terraces. Results are also consistent with a regional-scale lowering of hydrothermal reaction zone temperatures from north to south (except at the southernmost Mariner vent field) that leads to lower-temperature, higher-pH vent fluids relative to mid-ocean ridges of similar spreading rates (Mottl et al., 2011). These fluids are Cu- and Zn-poor and the deposits formed from these fluids are Cu-poor but Zn-rich. In contrast, at the Mariner vent field, higher-temperature and lower pH vent fluids are hypothesized to result from higher reaction zone temperatures and the localized addition of acidic magmatic volatiles (Mottl et al., 2011). The Mariner fluids are Cu- and Zn-rich and vent from SMS deposits that are rich in Cu but poor in Zn with moderate amounts of Pb. Thermodynamic calculations indicate that the contrasting metal contents of vent fluids and SMS deposits can be accounted for by vent fluid pH. Wurtzite/sphalerite ((Zn, Fe)S) and galena (PbS) are saturated at higher temperatures in higher-pH, Zn-, Cu-, and Pb-poor ELSC/VFR vent fluids, but are undersaturated at similar temperatures in low-pH, Zn-, Cu-, and Pb-rich vent fluids from the Mariner vent field. Indicators of pH in the ELSC and VFR SMS deposits include the presence of co-precipitated wurtzite and chalcopyrite along conduit linings in deposits formed from higher pH fluids, and different correlations between concentrations of Zn and Ag in bulk geochemical analyses. Significant positive bulk geochemical Zn:Ag correlations occur for deposits at vent fields where hydrothermal fluids have a minimum pH (at 25 °C) < 3.3, while correlations of Zn:Ag are weak or negative for deposits at vent fields where the minimum vent fluid pH (at 25 °C) > 3.6. Data show that the compositions of the mineral linings of open conduit chimneys (minerals present, mol% FeS in (Zn,Fe)S) that precipitate directly from hydrothermal fluids closely reflect the temperature and sulfur fugacity of sampled hydrothermal fluids. These mineral lining compositions thus can be used as indicators of hydrothermal fluid temperature and composition (pH, metal content, sulfur fugacity).

Lipid biomarker and microbial community of 49.6°E hydrothermal field at Southwest Indian Ocean Ridge

NASA Astrophysics Data System (ADS)

Lei, J.; Chu, F.; Yu, X.; Li, X.; Tao, C.

2012-12-01

In 2007, Chinese Research Cruises Discovered the First Active Hydrothermal Vent Field at the Ultraslow Spreading Southwest Indian Ridge. This study intent to get composition, evolution and origin information of lipid compounds in SWIR, and recognize the style of lipid biomarkers which have obviously indicative significance for community structure.Soluble organic matter were extracted from geological samples (including chimney sulfide, oxide, around hydrothermal vents) in Southwest Indian Ridge (SWIR), and divided into hydrocarbon, fatty acid component by column chromatography. GC, GC-MS, HPLC-MS were applied for composition and abundance analysis. Lipid in hydrothermal sulfide contains obvious isoprenoidal hydrocarbon biomarkers (Sq, IS40) and GDGTs (m/z=653) that associated with methanogenic archaea which belongs to Euryarchaeota, and iso /anti-iso fatty acid (iC15:0, aiC15:0, iC17:0, aiC17:0)which may originated from sulfate reducing bacteria (SRB).Lipids extracted from hydrothermal oxide lack isoprenoidal hydrocarbon, and Ph/C18 (0.57) is much lower than sulfide (1.22). Fatty acid compound of oxide include abundant saturated fatty (C16:0, C18:0) acid and mono-unsaturated fatty acids (C16:1n7, C18:1n7), but much less iso/anti-iso was detected. Lipid composition of hydrothermal oxide showed that archaea activity was seldom in hydrothermal oxide, and sulfur-oxidizing bacteria was the main microbial community.Study of Jaeschke (2010) showed that high temperature hydrothermal venting encompassed different microbial community from low temperature hydrothermal venting. Our study showed that in different stage of hydrothermal, microbial community structure may be distinct.

[Search for life in deep biospheres].

PubMed

Naganuma, Takeshi

2003-12-01

The life in deep biospheres bridges conventional biology and future exobiology. This review focuses the microbiological studies from the selected deep biospheres, i.e., deep-sea hydrothermal vents, sub-hydrothermal vents, terrestrial subsurface and a sub-glacier lake. The dark biospheres facilitate the emergence of organisms and communities dependent on chemolithoautotrophy, which are overwhelmed by photoautotrophy (photosynthesis) in the surface biospheres. The life at deep-sea hydrothermal vents owes much to chemolithoautotrophy based on the oxidation of sulfide emitted from the vents. It is likely that similarly active bodies such as the Jovian satellite Europa may have hydrothermal vents and associated biological communities. Anoxic or anaerobic condition is characteristic of deep subsurface biospheres. Subsurface microorganisms exploit available oxidants, or terminal electron acceptors (TEA), for anaerobic respiration. Sulfate, nitrate, iron (III) and CO2 are the representative TEAs in the deep subsurface. Below the 3000-4000 m-thick glacier on Antarctica, there have been >70 lakes with liquid water located. One of such sub-glacial lakes, Lake Vostok, is about to be drill-penetrated for microbiological studies. These deep biosphere "platforms" provide new knowledge about the diversity and potential of the Earth's life. The expertise obtained from the deep biosphere expeditions will facilitate the capability of exobiologial exploration.

Mineralization of Alvinella polychaete tubes at hydrothermal vents.

PubMed

Georgieva, M N; Little, C T S; Ball, A D; Glover, A G

2015-03-01

Alvinellid polychaete worms form multilayered organic tubes in the hottest and most rapidly growing areas of deep-sea hydrothermal vent chimneys. Over short periods of time, these tubes can become entirely mineralized within this environment. Documenting the nature of this process in terms of the stages of mineralization, as well as the mineral textures and end products that result, is essential for our understanding of the fossilization of polychaetes at hydrothermal vents. Here, we report in detail the full mineralization of Alvinella spp. tubes collected from the East Pacific Rise, determined through the use of a wide range of imaging and analytical techniques. We propose a new model for tube mineralization, whereby mineralization begins as templating of tube layer and sublayer surfaces and results in fully mineralized tubes comprised of multiple concentric, colloform, pyrite bands. Silica appeared to preserve organic tube layers in some samples. Fine-scale features such as protein fibres, extracellular polymeric substances and two types of filamentous microbial colonies were also found to be well preserved within a subset of the tubes. The fully mineralized Alvinella spp. tubes do not closely resemble known ancient hydrothermal vent tube fossils, corroborating molecular evidence suggesting that the alvinellids are a relatively recent polychaete lineage. We also compare pyrite and silica preservation of organic tissues within hydrothermal vents to soft tissue preservation in sediments and hot springs. © 2014 The Authors. Geobiology Published by John Wiley & Sons Ltd.

Discovery of hydrothermally active and extinct talc mounds on the Mid-Cayman Rise

NASA Astrophysics Data System (ADS)

Hodgkinson, M.; Murton, B. J.; Roberts, S.

2013-12-01

Since 1977, hydrothermal vents have been the subject of intense scientific interest due to their role in cooling the oceanic crust and global geochemical cycles. Until now, two types of hydrothermal system have been identified: one, driven by magmatic heat extruding ';black smoker' fluids; and another, involving serpentinisation of ultramafic rocks and the precipitation of carbonate/brucite chimneys. Here, we present details of a new, off-axis type of hydrothermal system consisting of mounds of predominately botryoidal talc (a magnesium-silicate) with accessory silica and copper sulphides, and chimneys exhaling fluids of moderate temperature and pH. Discovered on the Mid-Cayman Rise (MCR) in 2010, the Von Damm Vent Field (VDVF) features a NNW-ESE-trending line of four overlapping cones, the largest of which is 75 m high by 150 m in diameter. The VDVF is hosted in the gabbroic footwall of the Mount Dent Oceanic Core Complex (MDOCC), which includes serpentinised peridotite at depth. The largest cone vents clear fluids from two main orifices at its summit, with primary temperatures of 215°C. Elsewhere, both focussed and diffuse flow areas emit fluids with temperatures of up to 150°C. The surrounding ~1 m thick pelagic sediment contains abundant pockmarks that emit methane-rich fluids at temperatures of less than 10°C. During the return to the MCR in early 2013, several other talc mounds were discovered within a kilometre of the active VDVF. These inactive mounds also comprise an assemblage of botryoidal talc, silica, disseminated sulphides (including chalcopyrite) and sulphates. One of these mounds (Mystic Mount) is double the volume of the active VDVF. The unique dominance of talc as the major mineral forming the hydrothermal structures indicates unusual vent fluid compositions that are able to carry both copper (at high-temperatures) and precipitate magnesium silicate. Thermodynamic modelling indicates that talc precipitates on mixing a moderately acidic, silica rich fluid (e.g. the primary VDVF fluids) with only 2% of seawater. At lower pH (e.g. typical ';black smoker' fluids), the ratio jumps to over 90% while at high pH (e.g. ';Lost City' fluids) brucite and carbonate dominate. Estimates using recently measured vent temperatures and fluid fluxes indicate a heat flux of ~800 MW for the active VDVF. Assuming the primary vent fluid has remained largely unchanged, the VDVF could have grown in under 1000 years and Mystic Mount in ~2000 years. Both the hydrothermal mounds and faults in the surrounding gabbro share a NNW-ESE orientation that is consistent with a brittle structural control imposed by the flexural curvature of the MDOCC in response to the uplift of the lower oceanic crust along a low-angle detachment fault. We propose that these flexural faults provide pathways for fluids to ingress deep into the MDOCC where they react with both mafic rocks (producing high-temperature, low pH, sulphide and copper-bearing fluids), peridotites and carbonates (increasing the pH) resulting in a moderate pH, silica-rich fluid that precipitates talc on mixing with seawater. The presence of further, inactive, talc mounds within 1 km of the VDVF indicates hydrothermal activity on OCCs has been widespread and represents a significant but hitherto overlooked mechanism of crustal heat loss and chemical interaction with the ocean at slow-spreading ridges.

Size matters at deep-sea hydrothermal vents: different diversity and habitat fidelity patterns of meio- and macrofauna

PubMed Central

Gollner, Sabine; Govenar, Breea; Fisher, Charles R.; Bright, Monika

2015-01-01

Species with markedly different sizes interact when sharing the same habitat. Unravelling mechanisms that control diversity thus requires consideration of a range of size classes. We compared patterns of diversity and community structure for meio- and macrofaunal communities sampled along a gradient of environmental stress at deep-sea hydrothermal vents on the East Pacific Rise (9° 50′ N) and neighboring basalt habitats. Both meio- and macrofaunal species richnesses were lowest in the high-stress vent habitat, but macrofaunal richness was highest among intermediate-stress vent habitats. Meiofaunal species richness was negatively correlated with stress, and highest on the basalt. In these deep-sea basalt habitats surrounding hydrothermal vents, meiofaunal species richness was consistently higher than that of macrofauna. Consideration of the physiological capabilities and life history traits of different-sized animals suggests that different patterns of diversity may be caused by different capabilities to deal with environmental stress in the 2 size classes. In contrast to meiofauna, adaptations of macrofauna may have evolved to allow them to maintain their physiological homeostasis in a variety of hydrothermal vent habitats and exploit this food-rich deep-sea environment in high abundances. The habitat fidelity patterns also differed: macrofaunal species occurred primarily at vents and were generally restricted to this habitat, but meiofaunal species were distributed more evenly across proximate and distant basalt habitats and were thus not restricted to vent habitats. Over evolutionary time scales these contrasting patterns are likely driven by distinct reproduction strategies and food demands inherent to fauna of different sizes. PMID:26166922

The Role of Siliceous Hydrothermal Breccias in the Genesis of Volcanic Massive Sulphide Deposits - Ancient and Recent Systems

NASA Astrophysics Data System (ADS)

Costa, I. A.; Barriga, F. J.; Fouquet, Y.

2014-12-01

Siliceous hydrothermal breccias were sampled in two Mid-Atlantic Ridge active sites: Lucky Strike and Menez Gwen. These hydrothermal fields are located in the border of the Azorean plateau, southwest of the Azores islands where the alteration processes affecting basaltic rocks are prominent (Costa et al., 2003). The hydrothermal breccias are genetically related with the circulation of low temperature hydrothermal fluids in diffuse vents. The groundmass of these breccias precipitates from the fluid and consolidates the clastic fragments mostly composed of basalt. The main sources are the surrounding volcanic hills. Breccias are found near hydrothermal vents and may play an important role in the protection of subseafloor hydrothermal deposits forming an impermeable cap due to the high content in siliceous material. The amorphous silica tends to precipitate when the fluid is conductively cooled as proposed by Fouquet et al. (1998) after Fournier (1983). The process evolves gradually from an initial stage where we have just the fragments and circulating seawater. The ascending hydrothermal fluid mixes with seawater, which favours the precipitation of the sulphide components. Sealing of the initially loose fragments begins, the temperature rises below this crust, and the processes of mixing fluid circulation and conductive cooling are simultaneous. At this stage the fluid becomes oversaturated with respect to amorphous silica. This form of silica can precipitate in the open spaces of the porous sulphides and seal the system. Normally this can happen at low temperatures. At this stage the hydrothermal breccia is formed creating a progressively less permeable, eventually impermeable cap rock at the surface. Once the fluid is trapped under this impermeable layer, conductive cooling is enhanced and mixing with seawater is restricted, making the precipitation of amorphous silica more efficient. Since the first discovery and description of recent mineralized submarine hydrothermal deposits, comparison with ancient volcanic massive sulphide deposits is appropriate. The proposed model can explain some of the processes taking place in the early phase of formation of old deposits where equivalent siliceous material is found in the hanging wall of the ore bodies (e.g. Barriga and Fyfe, 1988).

Hydrothermal activity, functional diversity and chemoautotrophy are major drivers of seafloor carbon cycling.

PubMed

Bell, James B; Woulds, Clare; Oevelen, Dick van

2017-09-20

Hydrothermal vents are highly dynamic ecosystems and are unusually energy rich in the deep-sea. In situ hydrothermal-based productivity combined with sinking photosynthetic organic matter in a soft-sediment setting creates geochemically diverse environments, which remain poorly studied. Here, we use comprehensive set of new and existing field observations to develop a quantitative ecosystem model of a deep-sea chemosynthetic ecosystem from the most southerly hydrothermal vent system known. We find evidence of chemosynthetic production supplementing the metazoan food web both at vent sites and elsewhere in the Bransfield Strait. Endosymbiont-bearing fauna were very important in supporting the transfer of chemosynthetic carbon into the food web, particularly to higher trophic levels. Chemosynthetic production occurred at all sites to varying degrees but was generally only a small component of the total organic matter inputs to the food web, even in the most hydrothermally active areas, owing in part to a low and patchy density of vent-endemic fauna. Differences between relative abundance of faunal functional groups, resulting from environmental variability, were clear drivers of differences in biogeochemical cycling and resulted in substantially different carbon processing patterns between habitats.

The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes

NASA Astrophysics Data System (ADS)

Bennett, Sarah A.; Achterberg, Eric P.; Connelly, Douglas P.; Statham, Peter J.; Fones, Gary R.; German, Christopher R.

2008-06-01

We have conducted a study of hydrothermal plumes overlying the Mid-Atlantic Ridge near 5° S to investigate whether there is a significant export flux of dissolved Fe from hydrothermal venting to the oceans. Our study combined measurements of plume-height Fe concentrations from a series of 6 CTD stations together with studies of dissolved Fe speciation in a subset of those samples. At 2.5 km down plume from the nearest known vent site dissolved Fe concentrations were ˜ 20 nM. This is much higher than would be predicted from a combination of plume dilution and dissolved Fe(II) oxidation rates, but consistent with stabilisation due to the presence of organic Fe complexes and Fe colloids. Using Competitive Ligand Exchange-Cathodic Stripping Voltammetry (CLE-CSV), stabilised dissolved Fe complexes were detected within the dissolved Fe fraction on the edges of one non-buoyant hydrothermal plume with observed ligand concentrations high enough to account for stabilisation of ˜ 4% of the total Fe emitted from the 5° S vent sites. If these results were representative of all hydrothermal systems, submarine venting could provide 12-22% of the global deep-ocean dissolved Fe budget.

Novel Barite Chimneys at the Loki's Castle Vent Field Shed Light on Key Factors Shaping Microbial Communities and Functions in Hydrothermal Systems.

PubMed

Steen, Ida H; Dahle, Håkon; Stokke, Runar; Roalkvam, Irene; Daae, Frida-Lise; Rapp, Hans Tore; Pedersen, Rolf B; Thorseth, Ingunn H

2015-01-01

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.

On the global distribution of hydrothermal vent fields: One decade later

NASA Astrophysics Data System (ADS)

Beaulieu, S. E.; Baker, E. T.; German, C. R.

2012-12-01

Since the last global compilation one decade ago, the known number of active submarine hydrothermal vent fields has almost doubled. At the end of 2009, a total of 518 active vent fields was catalogued, with about half (245) visually confirmed and others (273) inferred active at the seafloor. About half (52%) of these vent fields are at mid-ocean ridges (MORs), 25% at volcanic arcs, 21% at back-arc spreading centers (BASCs), and 2% at intra-plate volcanoes and other settings. One third are in high seas, and the nations with the most known active vent fields within EEZs are Tonga, USA, Japan, and New Zealand. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. Here, we have comprehensively documented the percentage of strike length at MORs and BASCs that has been systematically explored for hydrothermal activity. As of the end of 2009, almost 30% of the ~60,000 km of MORs had been surveyed at least with spaced vertical profiles to detect hydrothermal plumes. A majority of the vents discovered at MORs in the past decade occurred at segments with < 60 mm/yr full spreading rate. Discoveries at ultra-slow MORs in the past decade included the deepest known vent (Beebe at Mid-Cayman Rise) and high-temperature black smoker vents (e.g., Dragon at SWIR and Loki's Castle at Mohns Ridge), and the highest temperature vent was measured at the slow-spreading S MAR (Turtle Pits). Using a previously published equation for the linear relationship between the number of active vent fields per 100 km strike length (F_s) vs. weighted-average full spreading rate (u_s), we predicted 676 vent fields remaining to be discovered at MORs. Even accounting for the lower F_s at slower spreading rates, almost half of the vents that are predicted remaining to be discovered at MORs are at ultra-slow to slow spreading rates (< 40 mm/yr) and about 1/3 at intermediate rates (40-80 mm/yr). MOR regions that are little explored tend to be at high latitudes, such as the ultra-slow to slow spreading Arctic MORs (e.g., Kolbeinsey and Mohns Ridges), the ultra-slow American-Antarctic Ridge, and the intermediate spreading Pacific-Antarctic Ridge. Although a greater percentage of the ~11,000 km of BASCs has been surveyed for hydrothermal activity, the discoveries at BASCs in the past decade were mainly at segments with intermediate to fast spreading rates. Using the same equation for F_s vs. u_s, we predicted 71 vent fields remaining to be discovered at BASCs, and most are likely to be found at ultra-slow and slow spreading segments (e.g., Andaman Basin, and central to northern Mariana Trough). With 2/3 of our overall predicted total vent fields at spreading ridges remaining to be discovered, we expect that the next decade of exploration will continue to yield new discoveries, leading to new insights into biogeography of vent fauna and the global impacts of fluxes of heat and materials from vents into our oceans.

Faulting and off-axis submarine massive sulfide accumulation at slow spreading mid-ocean ridges: A numerical modeling perspective

NASA Astrophysics Data System (ADS)

Andersen, C.; Theissen-Krah, S.; Hannington, M.; Rüpke, L.; Petersen, S.

2017-06-01

The potential of mining seafloor massive sulfide deposits for metals such as Cu, Zn, and Au is currently debated. One key challenge is to predict where the largest deposits worth mining might form, which in turn requires understanding the pattern of subseafloor hydrothermal mass and energy transport. Numerical models of heat and fluid flow are applied to illustrate the important role of fault zone properties (permeability and width) in controlling mass accumulation at hydrothermal vents at slow spreading ridges. We combine modeled mass-flow rates, vent temperatures, and vent field dimensions with the known fluid chemistry at the fault-controlled Logatchev 1 hydrothermal field of the Mid-Atlantic Ridge. We predict that the 135 kilotons of SMS at this site (estimated by other studies) can have accumulated with a minimum depositional efficiency of 5% in the known duration of hydrothermal venting (58,200 year age of the deposit). In general, the most productive faults must provide an efficient fluid pathway while at the same time limit cooling due to mixing with entrained cold seawater. This balance is best met by faults that are just wide and permeable enough to control a hydrothermal plume rising through the oceanic crust. Model runs with increased basal heat input, mimicking a heat flow contribution from along-axis, lead to higher mass fluxes and vent temperatures, capable of significantly higher SMS accumulation rates. Nonsteady state conditions, such as the influence of a cooling magmatic intrusion beneath the fault zone, also can temporarily increase the mass flux while sustaining high vent temperatures.

Diversity and phylogenetic analyses of bacteria from a shallow-water hydrothermal vent in Milos island (Greece).

PubMed

Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena; Yakimov, Michail; Vetriani, Costantino

2013-01-01

Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34 × 10(8) cells g(-1). The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94%), revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology.

Diversity and phylogenetic analyses of bacteria from a shallow-water hydrothermal vent in Milos island (Greece)

PubMed Central

Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena; Yakimov, Michail; Vetriani, Costantino

2013-01-01

Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34 × 108 cells g−1. The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94%), revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology. PMID:23847607

Fluxes to sediments underlying the Rainbow hydrothermal plume at 36°14‧N on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Cave, R. R.; German, C. R.; Thomson, J.; Nesbitt, R. W.

2002-06-01

A geochemical investigation has been conducted of a suite of four sediment cores collected from directly beneath the hydrothermal plume at distances of 2 to 25 km from the Rainbow hydrothermal field. As well as a large biogenic component (>80% CaCO3) these sediments record clear enrichments of the elements Fe, Cu, Mn, V, P, and As from hydrothermal plume fallout but only minor detrital background material. Systematic variations in the abundances of ;hydrothermal; elements are observed at increasing distance from the vent site, consistent with chemical evolution of the dispersing plume. Further, pronounced Ni and Cr enrichments at specific levels within each of the two cores collected from closest to the vent site are indicative of discrete episodes of additional input of ultrabasic material at these two near-field locations. Radiocarbon dating reveals mean Holocene accumulation rates for all four cores of 2.7 to 3.7 cm.kyr-1, with surface mixed layers 7 to 10+ cm thick, from which a history of deposition from the Rainbow hydrothermal plume can be deduced. Deposition from the plume supplies elements to the underlying sediments that are either directly hydrothermally sourced (e.g., Fe, Mn, Cu) or scavenged from seawater via the hydrothermal plume (e.g., V, P, As). Holocene fluxes into to the cores' surface mixed layers are presented which, typically, are an order of magnitude greater than ;background; authigenic fluxes from the open North Atlantic. One core, collected closest to the vent site, indicates that both the concentration and flux of hydrothermally derived material increased significantly at some point between 8 and 12 14C kyr ago; the preferred explanation is that this variation reflects the initiation/intensification of hydrothermal venting at the Rainbow hydrothermal field at this time-perhaps linked to some specific tectonic event in this fault-controlled hydrothermal setting.

Geochemistry of fluid phases and sediments: Relevance to hydrothermal circulation in Middle Valley, ODP Legs 139 and 169

USGS Publications Warehouse

Gieskes, J.M.; Simoneit, B.R.T.; Shanks, Wayne C.; Goodfellow, W.D.; James, R.H.; Baker, P.A.; Ishibashi, J.-I.

2002-01-01

Geochemical and isotopic studies of pore fluids and solid phases recovered from the Dead Dog and Bent Hill hydrothermal sites in Middle Valley (Ocean Drilling Program Leg 169) have been compared with similar data obtained previously from these sites during Ocean Drilling Program Leg 139. Although generally the hydrothermal systems reflect non-steady state conditions, the data allow an assessment of the history of the hydrothermal processes. Sediment K/A1 ratios as well as the distribution of anhydrite in the sediments suggest that the Dead Dog hydrothermal field has been, and still is, active. In contrast, similar data in the Bent Hill hydrothermal field indicate a waning of hydrothermal activity. Pore fluid and hydrothermal vent data in the Dead Dog hydrothermal field are similar in nature to the data collected during ODP Leg 139. In the area of the Bent Hill sulfide deposit, however, the pore water data indicate that recent wholesale flushing of the sediment column with relatively unaltered seawater has obliterated a previous record of hydrothermal activity in the pore fluids. Data from the deepest part of Hole 1035A in the Bent Hill locality show the presence of hydrothermal fluids at greater depths in this area. This suggests the origin of the hydrothermal fluids found to be emanating from Hole 1035F, which constitutes one of the first man made hydrothermal vents in the Middle Valley hydrothermal system. Similarly, CORKed Hole 858G, because of seal failures, has acted as a hydrothermal vent, with sulfide deposits forming inside the CORK. ?? 2002 Elsevier Science Ltd. All rights reserved.

Microbial Response to High Temperature Hydrothermal Forcing: AISICS Vent (Lucky Strike, 37°N, MAR) and Prokaryote Community as Example.

NASA Astrophysics Data System (ADS)

Henri, P. A.; Rommevaux, C.; Chavagnac, V.; Degboe, J.; Destrigneville, C.; Boulart, C.; Lesongeur, F.; Castillo, A.; Goodfroy, A.

2015-12-01

To study the hydrothermal forcing on microbial colonization, and impacts on the oceanic crust alteration, an integrated study was led at the Tour Eiffel hydrothermal site (Lucky Strike hydrothermal field, 37°N, MAR). We benefited from an annual survey between 2009 and 2011 of temperatures, along with sampling of focused and diffused fluids for chemical analysis, and chimney sampling and samples from microbial colonization experiments analyzed for prokaryotic composition and rock alteration study. The chemical composition of the fluids show an important increase in the CO2 concentration at the Eiffel Tower site between 2009 and 2010 followed by a decrease between 2010 and 2011. In 2011, several fluid samples show an important depletion in Si, suggesting that some Si was removed by interaction with the stockwork before emission. Our observations, regarding the previous studies of chemical fluid affected by a magmatic event lead us to suppose that a magmatic/tectonic event occurred under the Lucky Strike hydrothermal field between 2009 and 2010. The results of the prokaryotic communities' analysis show that a shift occurred in the dominant microbial metabolisms present in the colonizer retrieved in 2010 and the one retrieved in 2011. Archaeal communities shifted from chemolithoautotropic sulfite/thiosulfate reducers-dominated in 2010 to ammonia oxidizers-dominated in 2011. The bacterial communities also undergo a shift, from a community with diversified metabolisms in 2010 to a community strongly dominated by chemolithoautotrophic sulfide or hydrogen oxidation in 2011. Moreover, in terms of ecological preferendum, the Archaeal communities shifted from thermophilic-dominated to mesophilic-dominated. The present study underline the influence of modifications in gases compositions of hydrothermal fluids subsequently to a degassing of the magma chamber and their impact on the microbial communities living in the vicinity of hydrothermal vents at the Eiffel Tower site.

Shallow water submarine hydrothermal activity - A case study in the assessment of ocean acidification and fertilization

NASA Astrophysics Data System (ADS)

Zhang, J.; Yoshida, K.; Hagiwara, T.; Nagao, K.; Kusakabe, M.; Wang, B.; Chen, C. A.

2012-12-01

Most natural Shallow Water submarine Hydrothermal activates (SWH) along coastlines are related to hydrothermal eruptions involving heating of groundwater with the volcanic gas. These SWHs supply nutrients such as phosphorus and micro nutrients like iron to the euphotic zone, contributing to the overall natural fertility and primary productivity of coastal waters. However, SWHs also have a negative effect, dispersing toxic materials such as mercury and arsenic, and affecting the acidification of the surrounding waters. In this study, we evaluate the impact of "iron supply" and "ocean acidification" on the primary production in a coastal marine environment, at a SWH area discovered off Gueshandao Island, northeast Taiwan. In the past three years, expeditions were conducted and observations made around this SWH site. Divers, small boats and a research vessel (R/V OR1, Ocean University National Taiwan) were used to survey successively larger areas around the site. Some of the results obtained are as follows. Hydrothermal vents are located in a hilly terrain rich with hot spring water with gas erupting intermittently. There are two types of vents, roughly divided by color, yellow hot spring water with higher temperature >110 degC ejected from sulfur chimneys of various sizes, and colorless water with lower temperature ~80 degC ejected directly from the crevices of the andesitic bedrock. Natural sulfur solidifying in the mouth of a small chimney was captured by a video camera, and explosions were also observed at intervals of a few minutes. Sediment, sand and particles of sulfur were deposited on the sides to a radius of about 50 m condensing around the chimney. The bottom type changes from sand/particles to outcrop/rock away from the vents. Moreover, gas samples were collected from the vents; the ratios of gas concentrations (N2/Ar) and isotopic composition of noble gas (3He/4He) suggest that these volcanic gases are mantle-derived. Hydrothermal fluid with high pH values between 2.1 ~ 3.5 erupts from the vents, and diffuses toward the ocean surface affecting water up to 1 km way. The high pCO2 in the surface seawater is widely distributed, and the low pH value is also observed widely in mid-depth water (5 ~ 15 m). Water samples collected around the SHW site show higher concentrations of nutrients Si and P, and typically higher micro nutrients Mn, and even Fe as compared to normal seawater. Chlorophyll a in particular shows high values of several tens to hundreds times greater than normal subtropical seawater. We find for the first time in the nature, that SHW enhances the growth of phytoplankton, and contributes to primary productivity of the surrounding waters.

Ammonificins C and D, Hydroxyethylamine Chromene Derivatives from a Cultured Marine Hydrothermal Vent Bacterium, Thermovibrio ammonificans

PubMed Central

Andrianasolo, Eric H.; Haramaty, Liti; Rosario-Passapera, Richard; Vetriani, Costantino; Falkowski, Paul; White, Eileen; Lutz, Richard

2012-01-01

Chemical and biological investigation of the cultured marine hydrothermal vent bacterium, Thermovibrio ammonifican led to the isolation of two hydroxyethylamine chromene derivatives, ammonificins C and D. Their structures were elucidated using combination of NMR and mass spectrometry. Absolute stereochemistry was ascertained by comparison of experimental and calculated CD spectra. Biological evaluation and assessment were determined using the patented ApopScreen cell-based screen for apoptosis-induction. Ammonificins C and D induce apoptosis in micromolar concentrations. To our knowledge, this finding is the first report of chemical compounds that induce apoptosis from the cultured deep-sea marine organism, hydrothermal vent bacterium, Thermovibrio ammonificans. PMID:23170085

Reactive transport model of growth and methane production by high-temperature methanogens in hydrothermal regions of the subseafloor

NASA Astrophysics Data System (ADS)

Stewart, L. C.; Algar, C. K.; Topçuoğlu, B. D.; Fortunato, C. S.; Larson, B. I.; Proskurowski, G. K.; Butterfield, D. A.; Vallino, J. J.; Huber, J. A.; Holden, J. F.

2014-12-01

Hydrogenotrophic methanogens are keystone high-temperature autotrophs in deep-sea hydrothermal vents and tracers of habitability and biogeochemical activity in the hydrothermally active subseafloor. At Axial Seamount, nearly all thermophilic methanogens are Methanothermococcus and Methanocaldococcus species, making this site amenable to modeling through pure culture laboratory experiments coupled with field studies. Based on field microcosm incubations with 1.2 mM, 20 μM, or no hydrogen, the growth of methanogens at 55°C and 80°C is limited primarily by temperature and hydrogen availability, with ammonium amendment showing no consistent effect on total methane output. The Arrhenius constants for methane production by Methanocaldococcus jannaschii (optimum 82°C) and Methanothermococcus thermolithotrophicus (optimum 65°C) were determined in pure culture bottle experiments. The Monod constants for hydrogen concentration were measured by growing both organisms in a 2-liter chemostat at two dilution rates; 55°C, 65°C and 82°C; and variable hydrogen concentrations. M. jannaschii showed higher ks and Vmax constants than M. thermolithotrophicus. In the field, hydrogen and methane concentrations in hydrothermal end-member and low-temperature diffuse fluids were measured, and the concentrations of methanogens that grow at 55°C and 80°C in diffuse fluids were determined using most-probable-number estimates. Methane concentration anomalies in diffuse fluids relative to end-member hydrothermal concentrations and methanogen cell concentrations are being used to constrain a 1-D reactive transport model using the laboratory-determined Arrhenius and Monod constants for methane production by these organisms. By varying flow path length and subseafloor cell concentrations in the model, our goal is to determine solutions for the potential depth of the subseafloor biosphere coupled with the amount of methanogenic biomass it contains.

Cameras on the NEPTUNE Canada seafloor observatory: Towards monitoring hydrothermal vent ecosystem dynamics

NASA Astrophysics Data System (ADS)

Robert, K.; Matabos, M.; Sarrazin, J.; Sarradin, P.; Lee, R. W.; Juniper, K.

2010-12-01

Hydrothermal vent environments are among the most dynamic benthic habitats in the ocean. The relative roles of physical and biological factors in shaping vent community structure remain unclear. Undersea cabled observatories offer the power and bandwidth required for high-resolution, time-series study of the dynamics of vent communities and the physico-chemical forces that influence them. The NEPTUNE Canada cabled instrument array at the Endeavour hydrothermal vents provides a unique laboratory for researchers to conduct long-term, integrated studies of hydrothermal vent ecosystem dynamics in relation to environmental variability. Beginning in September-October 2010, NEPTUNE Canada (NC) will be deploying a multi-disciplinary suite of instruments on the Endeavour Segment of the Juan de Fuca Ridge. Two camera and sensor systems will be used to study ecosystem dynamics in relation to hydrothermal discharge. These studies will make use of new experimental protocols for time-series observations that we have been developing since 2008 at other observatory sites connected to the VENUS and NC networks. These protocols include sampling design, camera calibration (i.e. structure, position, light, settings) and image analysis methodologies (see communication by Aron et al.). The camera systems to be deployed in the Main Endeavour vent field include a Sidus high definition video camera (2010) and the TEMPO-mini system (2011), designed by IFREMER (France). Real-time data from three sensors (O2, dissolved Fe, temperature) integrated with the TEMPO-mini system will enhance interpretation of imagery. For the first year of observations, a suite of internally recording temperature probes will be strategically placed in the field of view of the Sidus camera. These installations aim at monitoring variations in vent community structure and dynamics (species composition and abundances, interactions within and among species) in response to changes in environmental conditions at different temporal scales. High-resolution time-series studies also provide a mean of studying population dynamics, biological rhythms, organism growth and faunal succession. In addition to programmed time-series monitoring, the NC infrastructure will also permit manual and automated modification of observational protocols in response to natural events. This will enhance our ability to document potentially critical but short-lived environmental forces affecting vent communities.

From Mantle to Microbe to Mollusc: How Animal-Microbial Symbioses Influence Carbon and Sulfur Cycling in Hydrothermal Vent Flows.

NASA Astrophysics Data System (ADS)

Girguis, P. R.; Beinart, R.

2014-12-01

Symbioses between animals and chemoautotrophic bacteria dominate many hydrothermal vents. In these associations, symbiotic bacteria harness energy and "fix" carbon from the oxidation of reduced chemicals such as sulfide, methane, and hydrogen that are found in venting fluids. At vents along the Eastern Lau Spreading Center (ELSC) in the South Pacific, snails and mussels with chemoautotrophic symbionts have been shown to harness energy via the oxidation of sulfide. However, partially oxidized sulfur species such as thiosulfate and polysulfides have also been detected in abundance in their habitats. No studies to date have established whether thiosulfate or other partially oxidized sulfur compounds are used by these symbiotic associations, nor have studies constrained the potential role that symbioses might play in sulfur biogeochemical cycles at diffuse vent flows. To address these questions, we used high-pressure, flow through incubations to study three symbiotic molluscs from the ELSC - the snails Alviniconcha and Ifremeria nautilei and the mussel Bathymodiolus brevior - at conditions mimicking those in situ. Via the use of isotopically labeled inorganic carbon, shipboard mass spectrometry and voltammetric microelectrodes, we quantified the production and consumption of different sulfur compounds by each of these symbioses. We established that the uptake and oxidation of either sulfide or thiosulfate could -to varying degrees- support carbon fixation in all three species. Notably, we also observed that some symbioses excreted thiosulfate and polysulfides under sulfidic conditions, suggesting that these symbioses are a source of partially oxidized sulfur species in the environment. We further observed spatial disparity in the carbon fixation rates among the individuals in our incubations that have implications for the variability of productivity in situ.Collectively, these data reveal that thiosulfate can support net autotrophy, and may be an ecologically important energy source for vent symbioses. Furthermore, symbioses-mediated sulfur transformations may influence the ecology of the free-living community by governing the production and consumption of reduced sulfur species in this habitat.

Bottom sediments and pore waters near a hydrothermal vent in Lake Baikal (Frolikha Bay)

USGS Publications Warehouse

Granina, L.Z.; Klerkx, J.; Callender, E.; Leermakers, M.; Golobokova, L.P.

2007-01-01

We discuss the redox environments and the compositions of bottom sediments and sedimentary pore waters in the region of a hydrothermal vent in Frolikha Bay, Lake Baikal. According to our results, the submarine vent and its companion nearby spring on land originate from a common source. The most convincing evidence for their relation comes from the proximity of stable oxygen and hydrogen isotope compositions in pore waters and in the spring water. The isotope composition indicates a meteoric origin of pore waters, but their major- and minor-element chemistry bears imprint of deep water which may seep through permeable faulted crust. Although pore waters near the submarine vent have a specific enrichment in major and minor constituents, hydrothermal discharge at the Baikal bottom causes a minor impact on the lake water chemistry, unlike the case of freshwater geothermal lakes in the East-African Rift and North America. ?? 2007.

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 – venting sediments (Milos Island, Greece)

PubMed Central

Bayraktarov, Elisa; Price, Roy E.; Ferdelman, Timothy G.; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive 35S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40–75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity. PMID:23658555

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 - venting sediments (Milos Island, Greece).

PubMed

Bayraktarov, Elisa; Price, Roy E; Ferdelman, Timothy G; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive (35)S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40-75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity.

Characterization of Chemosynthetic Microbial Mats Associated with Intertidal Hydrothermal Sulfur Vents in White Point, San Pedro, CA, USA

PubMed Central

Miranda, Priscilla J.; McLain, Nathan K.; Hatzenpichler, Roland; Orphan, Victoria J.; Dillon, Jesse G.

2016-01-01

The shallow-sea hydrothermal vents at White Point (WP) in Palos Verdes on the southern California coast support microbial mats and provide easily accessed settings in which to study chemolithoautotrophic sulfur cycling. Previous studies have cultured sulfur-oxidizing bacteria from the WP mats; however, almost nothing is known about the in situ diversity and activity of the microorganisms in these habitats. We studied the diversity, micron-scale spatial associations and metabolic activity of the mat community via sequence analysis of 16S rRNA and aprA genes, fluorescence in situ hybridization (FISH) microscopy and sulfate reduction rate (SRR) measurements. Sequence analysis revealed a diverse group of bacteria, dominated by sulfur cycling gamma-, epsilon-, and deltaproteobacterial lineages such as Marithrix, Sulfurovum, and Desulfuromusa. FISH microscopy suggests a close physical association between sulfur-oxidizing and sulfur-reducing genotypes, while radiotracer studies showed low, but detectable, SRR. Comparative 16S rRNA gene sequence analyses indicate the WP sulfur vent microbial mat community is similar, but distinct from other hydrothermal vent communities representing a range of biotopes and lithologic settings. These findings suggest a complete biological sulfur cycle is operating in the WP mat ecosystem mediated by diverse bacterial lineages, with some similarity with deep-sea hydrothermal vent communities. PMID:27512390

Estimating the Total Heat Flux from the ASHES Hydrothermal Vent Field Using the Sentry Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Crone, T. J.; Kinsey, J. C.; Mittelstaedt, E. L.

2017-12-01

Hydrothermal venting at mid-ocean ridges influences ocean chemistry, the thermal and chemical structure of the oceanic crust, and the evolution of unique and diverse autolithotrophically-supported ecosystems. Axially-hosted hydrothermal systems are responsible for 20-25% of the total heat flux out of Earth's interior, and likely play a large role in local as well as global biogeochemical cycles. Despite the importance of these systems, only a few studies have attempted to constrain the volume and heat flux of an entire hydrothermal vent field. In July of 2014 we used the Sentry autonomous underwater vehicle (AUV) to survey the water column over the ASHES hydrothermal vent field which is located within the caldera of Axial Seamount, an active submarine volcano located on the Juan de Fuca Ridge. To estimate the total heat and mass flux from this vent field, we equipped Sentry with a Nortek acoustic Doppler velocimeter (ADV), an inertial measurement unit (IMU), two acoustic Doppler current profilers (ADCPs), and two SBE3 temperature probes, allowing us to obtain precise measurements of fluid temperature and water velocity. The survey was designed using a control volume approach in which Sentry was pre-programmed to survey a 150-m-square centered over the vent field flying a grid pattern with 5-m track line spacing followed by a survey of the perimeter. This pattern was repeated multiple times during several 10-h dives at different altitudes, including 10, 20, 40, and 60 m above the seafloor, and during one 40-h survey at an altitude of 10 m. During the 40-h survey, the pattern was repeated nine times allowing us to obtain observations over several tidal cycles. Water velocity data obtained with Sentry were corrected for platform motion and then combined with the temperature measurements to estimate heat flux. The analysis of these data will likely provide the most accurate and highest resolution heat and mass flux estimates at a seafloor hydrothermal field to date.

The microbiology of deep-sea hydrothermal vent plumes: ecological and biogeographic linkages to seafloor and water column habitats.

PubMed

Dick, Gregory J; Anantharaman, Karthik; Baker, Brett J; Li, Meng; Reed, Daniel C; Sheik, Cody S

2013-01-01

Hydrothermal plumes are an important yet understudied component of deep-sea vent microbial ecosystems. The significance of plume microbial processes can be appreciated from three perspectives: (1) mediation of plume biogeochemistry, (2) dispersal of seafloor hydrothermal vent microbes between vents sites, (3) as natural laboratories for understanding the ecology, physiology, and function of microbial groups that are distributed throughout the pelagic deep sea. Plume microbiology has been largely neglected in recent years, especially relative to the extensive research conducted on seafloor and subseafloor systems. Rapidly advancing technologies for investigating microbial communities provide new motivation and opportunities to characterize this important microbial habitat. Here we briefly highlight microbial contributions to plume and broader ocean (bio)geochemistry and review recent work to illustrate the ecological and biogeographic linkages between plumes, seafloor vent habitats, and other marine habitats such as oxygen minimum zones (OMZs), cold seeps, and oil spills. 16S rRNA gene surveys and metagenomic/-transcriptomic data from plumes point to dominant microbial populations, genes, and functions that are also operative in OMZs (SUP05, ammonia-oxidizing Archaea, and SAR324 Deltaproteobacteria) and hydrocarbon-rich environments (methanotrophs). Plume microbial communities are distinct from those on the seafloor or in the subsurface but contain some signatures of these habitats, consistent with the notion that plumes are potential vectors for dispersal of microorganisms between seafloor vent sites. Finally, we put forward three pressing questions for the future of deep-sea hydrothermal plume research and consider interactions between vents and oceans on global scales.

The microbiology of deep-sea hydrothermal vent plumes: ecological and biogeographic linkages to seafloor and water column habitats

PubMed Central

Dick, Gregory J.; Anantharaman, Karthik; Baker, Brett J.; Li, Meng; Reed, Daniel C.; Sheik, Cody S.

2013-01-01

Hydrothermal plumes are an important yet understudied component of deep-sea vent microbial ecosystems. The significance of plume microbial processes can be appreciated from three perspectives: (1) mediation of plume biogeochemistry, (2) dispersal of seafloor hydrothermal vent microbes between vents sites, (3) as natural laboratories for understanding the ecology, physiology, and function of microbial groups that are distributed throughout the pelagic deep sea. Plume microbiology has been largely neglected in recent years, especially relative to the extensive research conducted on seafloor and subseafloor systems. Rapidly advancing technologies for investigating microbial communities provide new motivation and opportunities to characterize this important microbial habitat. Here we briefly highlight microbial contributions to plume and broader ocean (bio)geochemistry and review recent work to illustrate the ecological and biogeographic linkages between plumes, seafloor vent habitats, and other marine habitats such as oxygen minimum zones (OMZs), cold seeps, and oil spills. 16S rRNA gene surveys and metagenomic/-transcriptomic data from plumes point to dominant microbial populations, genes, and functions that are also operative in OMZs (SUP05, ammonia-oxidizing Archaea, and SAR324 Deltaproteobacteria) and hydrocarbon-rich environments (methanotrophs). Plume microbial communities are distinct from those on the seafloor or in the subsurface but contain some signatures of these habitats, consistent with the notion that plumes are potential vectors for dispersal of microorganisms between seafloor vent sites. Finally, we put forward three pressing questions for the future of deep-sea hydrothermal plume research and consider interactions between vents and oceans on global scales. PMID:23720658

Life and Death of Deep-Sea Vents: Bacterial Diversity and Ecosystem Succession on Inactive Hydrothermal Sulfides

PubMed Central

Sylvan, Jason B.; Toner, Brandy M.; Edwards, Katrina J.

2012-01-01

ABSTRACT Hydrothermal chimneys are a globally dispersed habitat on the seafloor associated with mid-ocean ridge (MOR) spreading centers. Active, hot, venting sulfide structures from MORs have been examined for microbial diversity and ecology since their discovery in the mid-1970s, and recent work has also begun to explore the microbiology of inactive sulfides—structures that persist for decades to millennia and form moderate to massive deposits at and below the seafloor. Here we used tag pyrosequencing of the V6 region of the 16S rRNA and full-length 16S rRNA sequencing on inactive hydrothermal sulfide chimney samples from 9°N on the East Pacific Rise to learn their bacterial composition, metabolic potential, and succession from venting to nonventing (inactive) regimes. Alpha-, beta-, delta-, and gammaproteobacteria and members of the phylum Bacteroidetes dominate all inactive sulfides. Greater than 26% of the V6 tags obtained are closely related to lineages involved in sulfur, nitrogen, iron, and methane cycling. Epsilonproteobacteria represent <4% of the V6 tags recovered from inactive sulfides and 15% of the full-length clones, despite their high abundance in active chimneys. Members of the phylum Aquificae, which are common in active vents, were absent from both the V6 tags and full-length 16S rRNA data sets. In both analyses, the proportions of alphaproteobacteria, betaproteobacteria, and members of the phylum Bacteroidetes were greater than those found on active hydrothermal sulfides. These shifts in bacterial population structure on inactive chimneys reveal ecological succession following cessation of venting and also imply a potential shift in microbial activity and metabolic guilds on hydrothermal sulfides, the dominant biome that results from seafloor venting. PMID:22275502

Hydrothermal exploration and astrobiology: oases for life in distant oceans?

NASA Astrophysics Data System (ADS)

German, Christopher R.

2004-04-01

High-temperature submarine hydrothermal fields on Earth's mid-ocean ridges play host to exotic ecosystems with fauna previously unknown to science. Because these systems draw significant energy from chemosynthesis rather than photosynthesis, it has been postulated that the study of such systems could have relevance to the origins of life and, hence, astrobiology. A major flaw to that argument, however, is that modern basalt-hosted submarine vents are too oxidizing and lack the abundant free hydrogen required to drive abiotic organic synthesis and/or the energy yielding reactions that the most primitive anaerobic thermophiles isolated from submarine vent-sites apparently require. Here, however, the progress over the past decade in which systematic search strategies have been used to identify previously overlooked venting on the slow-spreading Mid-Atlantic Ridge and the ultra-slow spreading Arctic and SW Indian Ridges is described. Preliminary identification of fault-controlled venting in a number of these sites has led to the discovery of at least two high-temperature hydrothermal fields hosted in ultramafic rocks which emit complex organic molecules in their greater than 360 °C vent-fluids. Whether these concentrations represent de novo organic synthesis within the hydrothermal cell remains open to debate but it is probable that many more such sites exist throughout the Atlantic, Arctic and SW Indian Oceans. One particularly intriguing example is the Gakkel Ridge, which crosses the floor of the Arctic Ocean. On-going collaborations between oceanographers and astrobiologists are actively seeking to develop a new class of free-swimming autonomous underwater vehicle, equipped with appropriate chemical sensors, to conduct long-range missions that will seek out, locate and investigate new sites of hydrothermal venting at the bottom of this, and other, ice-covered oceans.

Noble Gas geochemistry of the newly discovered hydrothermal fields in the Gulf of California: preliminary He-isotope ratios from the Alarcon Rise and Pescadero basin vent sites

NASA Astrophysics Data System (ADS)

Spelz, R. M.; Lupton, J. E.; Evans, L. J.; Zierenberg, R. A.; Clague, D. A.; Neumann, F.; Paduan, J. B.

2015-12-01

Numerous submarine deep-sea hydrothermal vents related to volcanic activity of the East Pacific Rise (EPR) are situated along the Pacific margins of Mexico. Until recently, active hydrothermal venting was unknown between the Guaymas Basin and 21°N on the EPR. MBARI's recent oceanographic surveys have added 7 new active vent sites. In this study, we aimed to sample the high-temperature hydrothermal fluids emanating from two distinct vent sites, named Meyibo and Auka, located in the Alarcon Rise and Pescadero Basin, respectively. Mantle-derived He have long been identified in hydrothermal fluid releases. The presence of He in aqueous fluids with 3He/4He ratios greater than in-situ production values (~0.05 RA, where RA = air He or 1.4 x 10-6) indicates the presence of mantle-derived melts. Preliminary analyses of He-isotope ratios derived from the newly discovered Meyibo and Auka hydrothermal fields show high 3He/4He ratios (~8RA), typical of MORB's. Auka vent field, characterized by chimneys composed of light carbonate minerals and oil-like hydrocarbons, and temperatures between 250-290oC, show average values of ~7.87RA. In contrast, the black-smokers at the Meyibo field, composed of dark sulfide minerals and temperatures over 350oC, yielded a higher He ratio of ~8.24RA. Recently, it has become clear that regional maximum mantle He values correlate with the velocity structure in the mantle, therefore, He has the potential to map regions of the underlying mantle that are undergoing partial melting. Seismic records could then be compared with the geochemical He ratio signal and supply information regarding tectonics and other processes involved in the generation of these gases. The data presented here will be completing a totally new inventory of He results from hydrothermal vents in the EPR and fault-termination basins distributed along the P-NA plate boundary in the Gulf of California. The results will be further coupled with the analysis of other geochemical indicators of mantle degassing to assess the relationship between He-isotopes and mantle velocity structure in the region.

S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal vent sulfides

USGS Publications Warehouse

Ono, Shuhei; Shanks, Wayne C.; Rouxel, O.J.; Rumble, D.

2007-01-01

Sulfide sulfur in mid-oceanic ridge hydrothermal vents is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/32S ratios of vent fluid H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different ??33S (?????33S-0.515 ??34S) values of up to 0.04??? even if ??34S values are identical. Detection of such small ??33S differences is technically feasible by using the SF6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006??? (2??). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and vent H2S collected from four active seafloor hydrothermal vent sites, East Pacific Rise (EPR) 9-10??N, 13??N, and 21??S and Mid-Atlantic Ridge (MAR) 37??N yield ??33S values ranging from -0.002 to 0.033 and ??34S from -0.5??? to 5.3???. The combined ??34S and ??33S systematics reveal that 73 to 89% of vent sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13??N and marcasite from MAR 37??N are in isotope disequilibrium not only in ??34S but also in ??33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal vent sulfides are characterized by low ??33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for interplay among seawater, oceanic crust and microbes in subseafloor hydrothermal sulfur cycles. ?? 2006 Elsevier Inc. All rights reserved.

Volcanic and Hydrothermal Activity of the North Su Volcano: New Insights from Repeated Bathymetric Surveys and ROV Observations

NASA Astrophysics Data System (ADS)

Thal, J.; Bach, W.; Tivey, M.; Yoerger, D.

2013-12-01

Bathymetric data from cruises in 2002, 2006, and 2011 were combined and compared to determine the evolution of volcanic activity, seafloor structures, erosional features and to identify and document the distribution of hydrothermal vents on North Su volcano, SuSu Knolls, eastern Manus Basin (Papua New Guinea). Geologic mapping based on ROV observations from 2006 (WHOI Jason-2) and 2011 (MARUM Quest-4000) combined with repeated bathymetric surveys from 2002 and 2011 are used to identify morphologic features on the slopes of North Su and to track temporal changes. ROV MARUM Quest-4000 bathymetry was used to develop a 10 m grid of the top of North Su to precisely depict recent changes. In 2006, the south slope of North Su was steeply sloped and featured numerous white smoker vents discharging acid sulfate waters. These vents were covered by several tens of meters of sand- to gravel-sized volcanic material in 2011. The growth of this new cone changed the bathymetry of the south flank of North Su up to ~50 m and emplaced ~0.014 km3 of clastic volcanic material. This material is primarily comprised of fractured altered dacite and massive fresh dacite as well as crystals of opx, cpx, olivine and plagioclase. There is no evidence for pyroclastic fragmentation, so we hypothesize that the fragmentation is likely related to hydrothermal explosions. Hydrothermal activity varies over a short (~50 m) lateral distance from 'flashing' black smokers to acidic white smoker vents. Within 2 weeks of observation time in 2011, the white smoker vents varied markedly in activity suggesting a highly episodic hydrothermal system. Based on ROV video recordings, we identified steeply sloping (up to 30°) slopes exposing pillars and walls of hydrothermal cemented volcaniclastic material representing former fluid upflow zones. These features show that hydrothermal activity has increased slope stability as hydrothermal cementation has prevented slope collapse. Additionally, in some places, hydrothermal crusts cover loose volcaniclastic material on the steep slopes and stabilize them.

Carbon and Metal Transformations Near the Continent-Ocean Margin Quantified with the ZAPS Instrument Package

DTIC Science & Technology

1999-09-30

Rudnicki M.D. and Klinkhammer G.P., (1999) A segment-scale survey of the Broken Spur hydrothermal plume , Deep-Sea Res. I, 46, 701-714. Guay C.K...We used our sled this year to explore the Bransfield Strait, Antarctica for hydrothermal vent sites (NSF -Office of Polar Programs; OPP-9725872). We...used the real time sensing capability to locate a vent field and map hydrothermal signals at several locations. We used the ZAPS package to investigate

Microbial community structure of hydrothermal deposits from geochemically different vent fields along the Mid-Atlantic Ridge

USGS Publications Warehouse

Flores, Gilberto E.; Campbell, James H.; Kirshtein, Julie D.; Meneghin, Jennifer; Podar, Mircea; Steinberg, Joshua I.; Seewald, Jeffrey S.; Tivey, Margaret Kingston; Voytek, Mary A.; Yang, Zamin K.; Reysenbach, Anna-Louise

2011-01-01

To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37°17'N, 32°16.3'W, depth 1600-1750m) and the ultramafic-hosted Rainbow (36°13'N, 33°54.1'W, depth 2270-2330m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.

Temporal change in megafauna at the Rose Garden hydrothermal vent (Galapagos Rift; eastern tropical Pacific)

NASA Astrophysics Data System (ADS)

Hessler, Robert R.; Smithey, William M.; Boudrias, Michel A.; Keller, Clifford H.; Lutz, Richard A.; Childress, James J.

1988-10-01

Hydrothermal vent communities must undergo substantial temporal change because of their dynamic physical milieu. This was verified in March 1985, when the Rose Garden hydrothermal vent on the Galapagos Rift was revisited after 5 1/4 years' absence. Comparison of photographs from the two visits revealed considerable faunal change. Among the hosts to chemoautotrophic bacteria, vestimentiferans were reduced from dominance to very low numbers. The mytilid was now extremely abundant and dominated vent openings. Vesicomyids also were more abundant. In general, vent-field suspension feeders had declined; anemones were distinctly less abundant, and siphonophores and enteropneusts were virtually absent. The decline of serpulids was likely, but less obvious. Of the mobile scavengers and carnivores, both galatheids and whelks were distincly more common. These community changes appear to result from both continuing recruitment and changes in the physical milieu. While the growth of some populations could have resulted from expanding opportunities, the population of at least one, the vesicomyid, had not achieved carrying capacity in 1979, and this could have pertained to others as well. The decrease of vestimentiferans may have been caused by declining vent-water flux, a process that would favor mytilids, or more complete vent-water filtration by the mytilids themselves. The same factors also could explain the reduction of vent-field filter feeders. These observations suggest that early stages in the cycle of Galapagos-type vent communities are likely to be dominated by vestimentiferans, but that bivalves will replace them with time.

Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents

DOE Data Explorer

Andrew Fowler

2015-10-01

Compilation of rare earth element and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.

Food Web Structure at South Su, Solwara 1 and Solwara 8 Hydrothermal Vent Sites (Manus Basin)

NASA Astrophysics Data System (ADS)

Honig, D. L.; Hsing, P.; Jones, R.; Schultz, T.; Sobel, A.; Thaler, A.; van Dover, C. L.

2008-12-01

A robust understanding of food webs in chemoautotrophically based hydrothermal vent ecosystems requires quantifying the input of local bacterial chemoautoptrophic production vs. photosynthetically derived debris from surface waters. As an initial step towards this goal for vent communities in Papua New Guinea's Manus Basin, we use isotopic ratios of carbon, nitrogen and sulfur to describe trophic relations among 17 invertebrate genera collected in July 2008 at the Solwara 1, Solwara 8 and South Su hydrothermal vent beds. Prior stable isotope work by Erickson, Macko and Van Dover (unpublished) at Manus Basin vent sites suggests that we will see relatively depleted ä13C and ä15N values for the primary consumers Ifremeria, Alviniconcha and Olgasolaris compared to secondary consumers like the mobile, scavenging genera Munidopsis, Austinograea, Alvinocaris and Chorocaris, sessile suspension feeders of the genera Eochinolasmus and Vulcanolepas, and the predatory sponge Abyssocladia. We further hypothesize that mobile fauna will exhibit greater within-genus variance of ä13C, ä15N and ä34S values than sessile genera due to mobile organisms' ability to forage for photosynthetically derived detritus.

Similarities and Differences in the Distributions of Hydrothermal Venting and the Formation of Seafloor Massive Sulfide Deposits at the Tui Malila and Mariner Vent Fields, Valu Fa Ridge

NASA Astrophysics Data System (ADS)

Tivey, M. K.; Evans, G. N.; Ferrini, V. L.; Spierer, H.

2016-12-01

High-resolution bathymetric mapping and recovery and study of samples from precisely known locations relative to local tectonic and volcanic features provide insight into the formation of seafloor massive sulfide deposits. Additional insight comes from repeat mapping efforts in 2005 and 2016 that provide details of relations and changes that may have occurred over time. Located 21 km apart on the Valu Fa Ridge, the Tui Malila and Mariner vent fields exhibit contrasting vent fluid chemistry, mineral deposit composition, deposit morphology, and seafloor morphology. At the Tui Malila vent field, near-neutral pH fluids with low metal contents vent from Zn- and Ba-rich, but Cu-poor deposits. The highest temperature fluids are found near the intersection of two faults and between volcanic domes. In contrast, acidic, metal-rich hydrothermal fluids at the Mariner vent field vent from Cu-rich, Zn-poor deposits. No discernable faults are present. At both the Tui Malila and Mariner vent fields, intermediate temperature fluids were sampled emanating from barite-rich deposits. At the Tui Malila vent field, intermediate fluids vent from flange-dominated edifices that are located on brecciated lava flow that overlays one of the two faults. Intermediate fluids at the Mariner vent field vent from squat terrace-like edifices located peripheral (10-15 m) to high-temperature chimney edifices, and seafloor morphology is dominated by brecciated lava flows. Thermodynamic models of mixing between high-temperature hydrothermal fluids and seawater that consider subsurface deposition of sulfide minerals and iron oxyhydroxide were used to reproduce the chemistry of intermediate fluids. This study suggests that the porous, brecciated lavas characteristic of these two vent fields provide sites for subsurface mixing and contribute to mineral deposition, with the faults at the Tui Malila vent field providing a pathway for subsurface fluid flow.

The scale of hydrothermal circulation of the Iheya-North field inferred from intensive heat flow measurements and ocean drilling

NASA Astrophysics Data System (ADS)

Masaki, Y.; Kinoshita, M.; Yamamoto, H.; Nakajima, R.; Kumagai, H.; Takai, K.

2014-12-01

Iheya-North hydrothermal field situated in the middle Okinawa trough backarc basin is one of the largest ongoing Kuroko deposits in the world. Active chimneys as well as diffuse ventings (maximum fluid temperature 311 °C) have been located and studied in detail through various geological and geophysical surveys. To clarify the spatial scale of the hydrothermal circulation system, intensive heat flow measurements were carried out and ~100 heat flow data in and around the field from 2002 to 2014. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 was carried out, and subbottom temperature data were obtained around the hydrothermal sites. During the JAMSTEC R/V Kaiyo cruise, KY14-01 in 2014, Iheya-North "Natsu" and "Aki" hydrothermal fields were newly found. The Iheya-Noth "Natsu" and "Aki" sites are located 1.2 km and 2.6 km south from the Iheya-North original site, respectively, and the maximum venting fluid temperature was 317 °C. We obtained one heat flow data at the "Aki" site. The value was 17 W/m2. Currently, the relationship between these hydrothermal sites are not well known. Three distinct zones are identified by heat flow values within 3 km from the active hydrothermal field. They are high-heat flow zone (>1 W/m2; HHZ), moderate-heat-flow zone (1-0.1 W/m2; MHZ); and low-heat-flow zone (<0.1 W/m2; LHZ). With increasing distance east of the HHZ, heat flow gradually decreases towards MHZ and LHZ. In the LHZ, temperature at 37m below the seafloor (mbsf) was 6 °C, that is consistent with the surface low heat flow suggesting the recharge of seawater. However, between 70 and 90 mbsf, the coarser sediments were cored, and temperature increased from 25 °C to 40°C. The temperature was 905°C at 151 mbsf, which was measured with thermoseal strips. The low thermal gradient in the upper 40 m suggests downward fluid flow. We infer that a hydrothermal circulation in the scale of ~1.5 km horizontal vs. ~a few hundred meters vertical.

Two Vent Fields Discovered at the Ultraslow Spreading Arctic Ridge System

NASA Astrophysics Data System (ADS)

Pedersen, R. B.; Thorseth, I. H.; Hellevang, B.; Schultz, A.; Taylor, P.; Knudsen, H. P.; Steinsbu, B. O.

2005-12-01

Two high-temperature vent fields were discovered at the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. Both vent fields are located within the southernmost segment of the Mohns Ridge approximately 50 km north of the West Jan Mayen Fracture Zone. Water depths along this segment range from 3800 meters close to the fracture zone to ~500 meters at the segment centre where the vent fields are located. The largest field - named "Gallionella Garden" - is situated within a rift graben where high- and low-temperature venting occurs along ridge-parallel normal faults and fissures. Presently we have documented high- and low-temperature venting along more then 2 km of the fault and fissure system in the area. The high-temperature venting takes place at around 550 mbsl at the base of a 100 meter high fault wall and was traced ~500 meters along strike. The field consists of at least 10 major vent sites, each composed of multiple chimneys that are up to 5-10 meters tall. There are also large areas of diffuse flow. The temperature of the vent fluids was measured to be above 260°C at a chimney orifice. This is at the boiling point of seawater at these water depths, and gas bubbling was observed at several of the vent sites. A sample of the top of a chimney consists of anhydrite, barite, sphalerite and pyrite. Outside the high-temperature vent area mounds of ferric iron are abundant. Such deposits have presently been traced along ~2 km of the faults and fissure system in the area. The deposits are predominantly made up of branching and twisted stalks comparable to those formed by the iron oxidizing bacteria Gallionella ferruginea showing that the precipitation is mediated by microbial activity. The temperatures below the upper crust of a mound were measured to be one degree above the ambient water temperature. The Fe-oxyhydroxides show Nd-isotope compositions similar to the basaltic crust and Sr-isotope compositions close to that of seawater, and may have formed from fluids composed of 90 percent seawater and 10 percent of an end-member hydrothermal fluid. Nd-concentrations suggest Fe-precipitate/fluid ratio of one to a million (ie. that 1 kg of Fe-deposits scavenged neodymium from one million litres of fluids). A second vent field was discovered 5 km southwest of "Gallionella Garden" at ~700 mbsl. The "Soria Moria" field is located at a volcanic ridge composed of recent lava flows and is about 100 meters across. The field consists of numerous chimneys emitting buoyant white smoker fluids, as well as irregular shaped mounds with flange structures discharging fluids of higher density then the ambient waters. White bacterial mats cover the seafloor and chimneys at both fields, and shrimp, sea spiders and colonies of sea anemones, crinoids and hydroids are associated with the vent fields. The hydrothermal plumes were detected acoustically using the exceptionally sensitive scientific echo sounders on "G.O.Sars". The acoustic backscatters images show that the hydrothermal plume above "Gallionella Garden" perturb the upper hydrographical layers, implying that this shallow vent field may "fertilize" the productive hydrographical layers in the area.

In Situ Materials Study in Hot Hydrothermal Vent Fluid

NASA Astrophysics Data System (ADS)

Holland, P. M.; Schindele, W. J.; Holland, C. E.; Lilley, M. D.; Olson, E. J.

2004-12-01

We are developing methods and technology for in situ sampling and analysis of volatiles from hot hydrothermal vent fluids inside the mixing boundary. These fluids can reach temperatures of up to 400° C and are known to be corrosive to most materials. While titanium has been the material of choice for contact with these fluids, we wanted to assess whether other materials, such as Hastelloy or nickel might be suitable for in situ sampling from hydrothermal vents. For the present study, small (1/16" o.d.) tubes of chemically pure titanium, Hastelloy C, and Nickel 200 were prepared, using 316 stainless steel as a control. These were placed in an assembly with other test items, and inserted into the hydrothermal vent Sully in the Main Endeavor Field on the Juan de Fuca Plate in June 2003 by the Jason II ROV operated from the R/V Thompson. The assembly was retrieved 46 days later after exposure to approximately 360° C hydrothermal vent fluid at a depth of 2200 m. Inspection showed the stainless steel to be completely eroded away and nickel to be extensively corroded, however both the Hastelloy and titanium tubes were in excellent condition with the 0.030" i.d. passages in the tubes remaining open. Other test items included a miniature titanium filtered inlet fitting containing an 80 mesh titanium screen made of 0.004" (0.1 mm) chemically pure titanium wire, an Inconel washer and a sapphire ball. Apart from some discoloration, there appeared to be no significant degradation in these materials apart from signs of etching on the sapphire.

Coexistence of Fe(II)- and Mn(II)-oxidizing bacteria govern the formation of deep sea umber deposits

NASA Astrophysics Data System (ADS)

Peng, Xiaotong; Ta, Kaiwen; Chen, Shun; Zhang, Lijuan; Xu, Hengchao

2015-11-01

The genesis of umber deposits has remained controversial for several decades. Recently, microbial Fe(II) oxidation associated with low-temperature diffuse venting has been identified as a key process for the formation of umber deposits, but the exact biogeochemical mechanisms involved to the precipitation of Mn oxides in umber deposits still remain unknown. Here, we used nano secondary ion mass spectrometer, synchrotron-based X-ray absorption spectroscopy, electron microscopy, and molecular techniques to demonstrate the coexistence of two types of metal-oxidizing bacteria within deep-sea hydrothermal umber deposits at the South Mid-Atlantic Ridge, where we found unique spheroids composed of biogenic Fe oxyhydroxides and Mn oxides in the deposits. Our data show that Fe oxyhydroxides and Mn oxides are metabolic by-products of lithotrophic Fe(II)-oxidizing bacteria and heterotrophic Mn(II)-oxidizing bacteria, respectively. The hydrothermal vents fuel lithotrophic microorganisms, which constitute a trophic base that might support the activities of heterogenic Mn(II)-oxidizing bacteria. The biological origin of umber deposits shed light on the importance of geomicrobiological interaction in triggering the formation of metalliferous deposits, with important implications for the generation of submarine Mn deposits and crusts.

Manganese(II)-oxidizing Bacillus spores in Guaymas Basin hydrothermal sediments and plumes.

PubMed

Dick, Gregory J; Lee, Yifan E; Tebo, Bradley M

2006-05-01

Microbial oxidation and precipitation of manganese at deep-sea hydrothermal vents are important oceanic biogeochemical processes, yet nothing is known about the types of microorganisms or mechanisms involved. Here we report isolation of a number of diverse spore-forming Mn(II)-oxidizing Bacillus species from Guaymas Basin, a deep-sea hydrothermal vent environment in the Gulf of California, where rapid microbially mediated Mn(II) oxidation was previously observed. mnxG multicopper oxidase genes involved in Mn(II) oxidation were amplified from all Mn(II)-oxidizing Bacillus spores isolated, suggesting that a copper-mediated mechanism of Mn(II) oxidation could be important at deep-sea hydrothermal vents. Phylogenetic analysis of 16S rRNA and mnxG genes revealed that while many of the deep-sea Mn(II)-oxidizing Bacillus species are very closely related to previously recognized isolates from coastal sediments, other organisms represent novel strains and clusters. The growth and Mn(II) oxidation properties of these Bacillus species suggest that in hydrothermal sediments they are likely present as spores that are active in oxidizing Mn(II) as it emerges from the seafloor.

New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece

PubMed Central

Kilias, Stephanos P.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N.; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J.; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

2013-01-01

We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe3+-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe2+-oxidation, dependent on microbially produced nitrate. PMID:23939372

Primary Formation Path of Formaldehyde in Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Inaba, Satoshi

2018-03-01

Formaldehyde is abundant in the universe and one of the fundamental molecules for life. Hydrothermal vents produce a substantial amount of hydrogen molecules by serpentinization and promote reductive reactions of single carbon compounds. The abundance of formaldehyde is expected to be low due to the high Gibbs free energy in hydrothermal vents. We consider two competing formation pathways of formaldehyde: (1) the reduction of CO by H2 and (2) the reduction of HCOOH by H2 to form a methanediol, followed by the dehydration of the methanediol. We performed a number of quantum chemical simulations to examine the formation of formaldehyde in the gas phase as well as in aqueous solution. The energy barrier is significantly reduced by the catalytic effect of water molecules in aqueous solution and becomes lowest when a water cluster consisted of 5 water molecules catalyzes the reduction. The energy barrier to form a methanediol by the reduction of HCOOH is lower by 17.5 kcal/mol than that to form a formaldehyde by the reduction of CO. Considering the low energy barrier to dehydrate methanediol, the primary pathway to form formaldehyde in hydrothermal vents is concluded to be the reduction of HCOOH by H2, followed by the dehydration of methanediol.

Functional Metagenomic Investigations of Microbial Communities in a Shallow-Sea Hydrothermal System

PubMed Central

Tang, Kai; Liu, Keshao; Jiao, Nianzhi; Zhang, Yao; Chen, Chen-Tung Arthur

2013-01-01

Little is known about the functional capability of microbial communities in shallow-sea hydrothermal systems (water depth of <200 m). This study analyzed two high-throughput pyrosequencing metagenomic datasets from the vent and the surface water in the shallow-sea hydrothermal system offshore NE Taiwan. This system exhibited distinct geochemical parameters. Metagenomic data revealed that the vent and the surface water were predominated by Epsilonproteobacteria (Nautiliales-like organisms) and Gammaproteobacteria ( Thiomicrospira -like organisms), respectively. A significant difference in microbial carbon fixation and sulfur metabolism was found between the vent and the surface water. The chemoautotrophic microorganisms in the vent and in the surface water might possess the reverse tricarboxylic acid cycle and the Calvin−Bassham−Benson cycle for carbon fixation in response to carbon dioxide highly enriched in the environment, which is possibly fueled by geochemical energy with sulfur and hydrogen. Comparative analyses of metagenomes showed that the shallow-sea metagenomes contained some genes similar to those present in other extreme environments. This study may serve as a basis for deeply understanding the genetic network and functional capability of the microbial members of shallow-sea hydrothermal systems. PMID:23940820

Geothermic Potential Assessment of hydrothermal vents of Township Barranca De Upia - Meta - Colombia

NASA Astrophysics Data System (ADS)

Chica, J.; Chicangana, G.; Eco Energy Research Group

2013-05-01

Hydrothermal vents have been traditionally exploited in Colombia as a source of tourism revenue such as pools and saunas. Leaving aside its high potential for geothermal power generation in applications like heating, drying, cooling, extensive use in crops, livestock, electricity generation and more. Currently the use given to this natural resource in the town of Barranca de Upia in Meta department, central Colombia, is like Wellness Centre. However, the geothermal gradient for the area where hydrothermal vents occur, indicates that the water emerges at temperatures above 70 ° C (Alfaro et al., 2003), which opens a window of opportunity to assess their geothermal potential, in order to know the actual energy potential of the region as an option of augmenting their development. this research is the analysis of information gathered from databases in gravimetry and magnetometry of the study area and the temperatures measured in wells derived from the oil industry. Based on that information, a numerical analysis of the data will be performed in order to establish a model to parameterize the energy potential of the study area and identify possible uses of the energy contained by the hydrothermal vents.

Primary Formation Path of Formaldehyde in Hydrothermal Vents.

PubMed

Inaba, Satoshi

2018-03-01

Formaldehyde is abundant in the universe and one of the fundamental molecules for life. Hydrothermal vents produce a substantial amount of hydrogen molecules by serpentinization and promote reductive reactions of single carbon compounds. The abundance of formaldehyde is expected to be low due to the high Gibbs free energy in hydrothermal vents. We consider two competing formation pathways of formaldehyde: (1) the reduction of CO by H 2 and (2) the reduction of HCOOH by H 2 to form a methanediol, followed by the dehydration of the methanediol. We performed a number of quantum chemical simulations to examine the formation of formaldehyde in the gas phase as well as in aqueous solution. The energy barrier is significantly reduced by the catalytic effect of water molecules in aqueous solution and becomes lowest when a water cluster consisted of 5 water molecules catalyzes the reduction. The energy barrier to form a methanediol by the reduction of HCOOH is lower by 17.5 kcal/mol than that to form a formaldehyde by the reduction of CO. Considering the low energy barrier to dehydrate methanediol, the primary pathway to form formaldehyde in hydrothermal vents is concluded to be the reduction of HCOOH by H 2 , followed by the dehydration of methanediol.

A biogeographic network reveals evolutionary links between deep-sea hydrothermal vent and methane seep faunas

PubMed Central

2016-01-01

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. PMID:27974524

Submarine thermal springs on the Galapagos Rift

USGS Publications Warehouse

Corliss, J.B.; Dymond, J.; Gordon, L.I.; Edmond, J.M.; Von Herzen, R. P.; Ballard, Richard D.; Green, K.; Williams, D.; Bainbridge, A.; Crane, K.; Van Andel, T. H.

1979-01-01

The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis

Environmental controls on chemoautotrophic primary producers at deep-sea vents

NASA Astrophysics Data System (ADS)

Le Bris, Nadine; Mullineaux, Lauren; Sievert, Stefan

2014-05-01

High biomasses and fast growth rates of dominant chemosynthetic species characterize hydrothermal ecosystems, raising the issue of their contribution to energy transfer and carbon cycling in the deep-sea. Addressing this issue, however, needs to account for the temporal instability of hydrothermal systems, both, in terms of biological colonization and habitat conditions. Volcanic eruptions on mid-ocean ridges offer the opportunity to investigate the environmental conditions favoring the successive modes of chemoautotrophic primary production (i.e. free living microbes and symbiotic invertebrates). In that perspective, habitat-scale approaches distinguish from vent field-scale approaches based on fluid composition and provide relevant information on environmental constraints exerted at different stages of colonization focusing on parameters linked with physiological limits and available energy. Investigation of habitat physicochemical properties along a typical successional sequence of recolonization at 9°50'N EPR diffuse-flow vents, between 2006 and 2014, was performed in order to examine potential changes in environmental features associated with chemoautotrophic primary producers, from early microbial colonizers to symbiotic invertebrates. Combined in situ measurements of temperature, pH and hydrogen sulfide were used and their variability documented over a series of assemblages characterizing recolonization stages. The distributions of mature assemblages of dominant invertebrate species associate with substantial differences in habitat conditions, pointing to a strong influence of habitat properties on potential productivity. Among the differences observed, however, the amplitude and rate of environmental fluctuation appear more important than average conditions in the succession, highlighting the role of spatial heterogeneity and temporal dynamics as a control on primary producers. Invertebrate species acting as engineer species are expected to play a primary role in the rate of organic carbon formed over the lifetime of a vent and potentially transferred to adjacent ecosystems.

Arsenic bioaccumulation and biotransformation in deep-sea hydrothermal vent organisms from the PACMANUS hydrothermal field, Manus Basin, PNG

NASA Astrophysics Data System (ADS)

Price, Roy E.; Breuer, Christian; Reeves, Eoghan; Bach, Wolfgang; Pichler, Thomas

2016-11-01

Hydrothermal vents are often enriched in arsenic, and organisms living in these environments may accumulate high concentrations of this and other trace elements. However, very little research to date has focused on understanding arsenic bioaccumulation and biotransformation in marine organisms at deep-sea vent areas; none to date have focused organisms from back-arc spreading centers. We present for the first time concentration and speciation data for As in vent biota from several hydrothermal vent fields in the eastern Manus basin, a back-arc basin vent field located in the Bismark Sea, western Pacific Ocean. The gastropods Alviniconcha hessleri and Ifremeria nautilei, and the mussel Bathymodiolus manusensis were collected from diffuse venting areas where pH was slightly lower (6.2-6.8), and temperature (26.8-10.5 °C) and arsenic concentrations (169.5-44.0 nM) were higher than seawater. In the tissues of these organisms, the highest total measured As concentrations were in the gills of A. hessleri (5580 mg kg-1), with 721 mg kg-1 and 43 mg kg-1 in digestive gland and muscle, respectively. I. nautilei contained 118 mg kg-1 in the gill, 108 mg kg-1 in the digestive gland and 22 mg kg-1 in the muscle. B. manusensis contained 15.7 mg kg-1 in the digestive gland, followed by 9.8 mg kg-1 and 4.5 mg kg-1 in its gill and muscle tissue, respectively. We interpret the decreasing overall total concentrations in each organism as a function of distance from the source of hydrothermally derived As. The high concentration of arsenic in A. hessleri gills may be associated with elemental sulfur known to occur in this organism as a result of symbiotic microorganisms. Arsenic extracted from freeze-dried A. hessleri tissue was dominated by AsIII and AsV in the digestive gland (82% and 16%, respectively) and gills (97% AsIII, 2.3% AsV), with only 1.8% and 0.2% arsenobetaine (As-Bet) in the digestive gland and gills, respectively. However, the muscle contained substantial amounts of As-Bet (42% As-Bet compared to 48% AsIII and 10% AsV), suggesting As-Bet is a metabolite. Trace arsenosugar (SO4-sug) was observed in digestive gland and gills only. The other snail, I. nautilei, was also dominated by AsIII and AsV in digestive glands (82, 10%) and gills (80, 10%), with 6-9% As-Bet, but its muscle contained 62% As-Bet and 32% AsIII, with 7% trimethylarsoniopropionate (TMAP). Trace dimethylarsinic acid (DMAV) was observed in its gills, and trace TMAP and arsenocholine (AC) was observed in digestive glands. The mussel B. manusensis was dominated by As-Bet in all three tissue types. Digestive gland and gills contained 22% AsIII, 5-10% AsV, 20-25% DMAV, along with some TMAP and tetramethylarsonium ion (TETRA). However, the muscle contained significantly more As-Bet (91.6%), with the only other species being AsIII (8.4%). Unfortunately, as is often the case in bioaccumulation and biotransformation studies, extraction efficiencies were low, limiting any rigorous interpretation of arsenic biotransformation patterns. Through process of elimination, we suggest that arsenosugars may be synthesized by H2S-oxidizing chemotrophic microbial mats, ultimately leading to the syntheses of As-Bet within vent organisms. However, because As-sugs rarely occur in deep-sea vent organisms, As-Bet, as well as TMAP, AC, and TETRA could also potentially be synthesized directly by the "Edmonds" pathway, the proposed arseno-analog to amino acid formation, without the necessity for arsenosugar formation as an intermediate. Future research should endeavor for more comprehensive extraction of organoarsenicals.

Spatial variability in recruitment of benthos near drilling sites in the Iheya North hydrothermal field in the Okinawa Trough

NASA Astrophysics Data System (ADS)

Nakamura, Masako; Nakajima, Yuichi; Watanabe, Hiromi Kayama; Sasaki, Takenori; Yamamoto, Hiroyuki; Mitarai, Satoshi

2018-05-01

Due to increasing anthropogenic impacts on deep-sea hydrothermal vent ecosystems, it is essential to understand population structure and maintenance through larval recruitment and recovery of vent faunas after disturbances. In this study, we quantified vent animal recruitment in the Okinawa Trough, in the western Pacific Ocean. This is the first study to investigate recruitment patterns at a man-made hydrothermal vent. Colonization plates were deployed at three sites. Site 1 manifested new hydrothermal shimmering with small chimneys, white bacterial mats, and some alvinocaridid shrimp that arrived after drilling. Site 2 showed no evidence of newly arrived foundation species after drilling, and Site 3 had pre-existing animal communities in the vicinity of the new vent. Twenty-two months after deployment, colonization plates were retrieved and recruited animals were inventoried. Species composition and abundance differed among sites, but relatively high similarity in species composition was observed at Sites 1 and 3, though not at Site 2. Newly established communities on the plates at Sites 1 and 2 (no pre-existing fauna) showed lower species richness and abundance than at Site 3. Differences in abundance and size-frequency distributions of major recruits on the plates (i.e. Lepetodrilus nux, Bathymodiolus spp.) suggest the importance of reproductive and early life-history characteristics in spatial variability of recruitment. Lepetodrilus nux populations established on the plates at Site 1 showed high genetic connectivity. These results illustrate the importance of localized recruitment, which may have a significant impact on sustainability of vent faunal populations, despite the existence of regional metapopulations.

Subseafloor microbial communities in hydrogen‐rich vent fluids from hydrothermal systems along the Mid‐Cayman Rise

PubMed Central

Reveillaud, Julie; Reddington, Emily; McDermott, Jill; Algar, Christopher; Meyer, Julie L.; Sylva, Sean; Seewald, Jeffrey; German, Christopher R.

2016-01-01

Summary Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid‐Cayman Rise each exhibits novel geologic settings and distinctively hydrogen‐rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition, diversity, and function of microbes in venting fluids from both sites: Piccard, the world's deepest vent site, hosted in mafic rocks; and Von Damm, an adjacent, ultramafic‐influenced system. Von Damm hosted a wider diversity of lineages and metabolisms in comparison to Piccard, consistent with thermodynamic models that predict more numerous energy sources at ultramafic systems. There was little overlap in the phylotypes found at each site, although similar and dominant hydrogen‐utilizing genera were present at both. Despite the differences in community structure, depth, geology, and fluid chemistry, energetic modelling and metagenomic analysis indicate near functional equivalence between Von Damm and Piccard, likely driven by the high hydrogen concentrations and elevated temperatures at both sites. Results are compared with hydrothermal sites worldwide to provide a global perspective on the distinctiveness of these newly discovered sites and the interplay among rocks, fluid composition and life in the subseafloor. PMID:26663423

Previously unsuspected dietary habits of hydrothermal vent fauna: the bactivorous shrimp Rimicaris hybisae can be carnivorous or even cannibalistic

NASA Astrophysics Data System (ADS)

Versteegh, Emma; Van Dover, Cindy; Coleman, Max

2014-05-01

Most hydrothermal vents support productive communities, with chemosynthetic bacteria at the base of the food web. They form a potentially important link in global geochemical cycles. However, few data yet exist on their significance in ocean biogeochemistry and related ecological processes. We present results on the structure of part of the food web around hydrothermal vents of the Mid-Cayman Rise (MCR), revealing previously unknown life-history traits of the alvinocarid shrimp species Rimicaris hybisae. We also demonstrate that stable carbon isotope ratios (δ13C values) are an excellent tracer of trophic positions in these ecosystems, in spite of recent findings arguing otherwise. Two hydrothermal vent fields have been described at the ultra-slow spreading ridge of the MCR. These include the world's deepest hydrothermal vents (Piccard field ~4985 m), which support a food web, which includes bactivorous shrimp and carnivorous anemones. The nearby Von Damm vent field (~2300 m) supports a more complex food web, with more primary producers, and probably some influx of photosynthetically produced carbon. Rimicaris hybisae is abundant at both known MCR vent fields and shows a high degree of spatial variability in population structure and reproductive features. In previous work it has been considered bactivorous. Large variations in tissue δ13C values remained largely unexplained, and it has been argued that δ13C values are not a good food web tracer in hydrothermal vent ecosystems. We observed that shrimp tended to be either in dense aggregations on active chimneys or more sparsely distributed, peripheral shrimp in ambient or near-ambient temperatures. With the hypothesis that varying δ13C values show real differences in food sources between individuals and that shrimp in different locales might have different diets, we collected shrimp from both environments at the Von Damm site during E/V Nautilus (NA034, August 2013) and examined their gut contents. Stomach contents of all shrimp from dense aggregations at the Von Damm field (n=18) consisted of white, amorphous material that resembled bacteria. Sparsely distributed peripheral shrimp (~1 m from dense aggregations) had stomachs filled with fragments of crustacean exoskeleton (5/13), a mixture of bacteria-like material and crustacean exoskeleton (3/13), or bacteria-like material only (5/13). We then analyzed the δ13C, δ15N and δ34S compositions of the shrimp gut contents. We show that R. hybisae switches its diet from exclusively chemosynthetic bacteria to crustacea during its life history. This is reflected in dramatically lower δ13C values of shrimp tissues, and slightly elevated δ15N values. To further support our findings, measurements of δ34S values on the same individuals and their gut contents are ongoing. Our contribution to disentangling the food web around the MCR hydrothermal vents fields helps quantify their carbon budget and determine their role in ocean carbon cycling.

Chemistry of a serpentinization-controlled hydrothermal system at the Lost City hydrothermal vent field

NASA Astrophysics Data System (ADS)

Ludwig, K. A.; Kelley, D. S.; Butterfield, D. A.; Nelson, B. K.; Karson, J. A.

2003-12-01

The Lost City Hydrothermal Field (LCHF), at 30° N near the Mid-Atlantic Ridge, is an off-axis, low temperature, high-pH, ultramafic-hosted vent system. Within the field, carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the vent structures and fluids at the LCHF is controlled by reactions between seawater and ultramafic rocks beneath the Atlantis massif. Mixing of warm alkaline vent fluids with seawater causes precipitation of calcium carbonate and growth of the edifaces, which range from tall, graceful pinnacles to fragile flanges and colloform deposits. Geochemical and petrological analyses of the carbonate rocks reveal distinct differences between the active and extinct structures. Actively venting chimneys and flanges are extremely porous, friable formations composed predominantly of aragonite and brucite. These structures provide important niches for well-developed microbial communities that thrive on and within the chimney walls. Some of the active chimneys may also contain the mineral ikaite, an unstable, hydrated form of calcium carbonate. TIMS and ICP-MS analyses of the carbonate chimneys show that the most active chimneys have low Sr isotope values and that they are low in trace metals (e.g., Mn, Ti, Pb). Active structures emit high-pH, low-Mg fluids at 40-90° C. The fluids also have low Sr values, indicating circulation of hydrothermal solutions through the serpentinite bedrock beneath the field. In contrast to the active structures, extinct chimneys are less porous, are well lithified, and they are composed predominantly of calcite that yields Sr isotopes near seawater values. Prolonged lower temperature seawater-hydrothermal fluid interaction within the chimneys results in the conversion of aragonite to calcite and in the enrichment of some trace metals (e.g., Mn, Ti, Co, Zn). It also promotes the incorporation of foraminifera within the outer, cemented walls of the carbonate structures. The Lost City system represents a novel natural laboratory for observing hydrothermal and biological activity in a system controlled by moderate temperature serpentinization reactions. The LCHF is the only vent field of its kind known to date; however, it is likely not unique along the global mid-ocean ridge spreading network.

Nanoparticulate, sub-micron and micron sized particles emanating from hydrothermal vents

NASA Astrophysics Data System (ADS)

Luther, G. W., III; Gartman, A.; Findlay, A.; Yucel, M.; Chan, C. S. Y.

2015-12-01

Recent data from Geotraces cruises over the MAR and SEPR indicate dissolved and particulate Fe enrichment in waters 1000 and 4000 km from their vent sources, respectively. Deep-sea hydrothermal vents and the waters in the reactive mixing zone above vent orifices have been suggested to be an important source of fine material that can pass through normal filters (0.2 and 0.4 μm). In this work, nanoparticles are defined operationally as that which can pass through a 0.2 μm filter. We investigated two vent sites (Lau Basin and the MAR). Chimneys from both vent sites have fluids that can be sulfide rich or metal rich. We also present chemical and physical chemical data (SEM-EDS, TEM, XRD, EELS) showing some of the materials found in these (nano)particulate phases including pyrite, metal sulfides, silicate and aluminosilicate material. Enrichment of Mg and K in the latter suggest that reverse weathering may occur in the waters within 1-2 meters of the vent orifice where vent waters mix with cold oxygenated bottom waters.

Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea Hydrothermal System

NASA Astrophysics Data System (ADS)

Lu, G. S.; Amend, J.

2015-12-01

Shallow-sea hydrothermal ecosystems are dynamic, high-energy systems influenced by sunlight and geothermal activity. They provide accessible opportunities for investigating thermophilic microbial biogeochemical cycles. In this study, we report biogeochemical data from a shallow-sea hydrothermal system offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with hydrothermally influenced sediments extending into nearby sea grass area. Geochemical analysis and deep sequencing provide high-resolution information on the geochemical patterns, microbial diversity and metabolic potential in a two-meter transect. The venting fluid is elevated in temperature (~70oC), low in pH (~4), and enriched in reduced species. The geochemical pattern shows that the profile is affected by not only seawater dilution but also microbial regulation. The microbial community in the deepest section of vent core (10-12 cm) is largely dominated by thermophilic archaea, including a methanogen and a recently described Crenarcheon. Mid-core (6-8 cm), the microbial community in the venting area switches to the hydrogen utilizer Aquificae. Near the sediment-water interface, anaerobic Firmicutes and Actinobacteria dominate, both of which are commonly associated with subsurface and hydrothermal sites. All other samples are dominated by diverse Proteobacteria. The sulfate profile is strongly correlated with the population size of delta- and episilon-proteobactia. The dramatic decrease in concentrations of As and Mn in pore fluids as a function of distance from the vent suggests that in addition to seawater dilution, microorganisms are likely transforming these and other ions through a combination of detoxification and catabolism. In addition, high concentrations of dissolved Fe are only measurable in the shallow sea grass area, suggesting that iron-transforming microorganisms are controlling Fe mobility, and promoting biomineralization. Taken together, these samples represent the effects of submarine venting on sediment microbial communities both vertically and horizontally in the predicted fluid flow path, and will provide a detailed investigation of genetic potential for biogeochemical cycling at Paleochori Bay.

A serpentinite-hosted ecosystem in the Southern Mariana Forearc

NASA Astrophysics Data System (ADS)

Ohara, Yasuhiko; Reagan, Mark K.; Fujikura, Katsunori; Watanabe, Hiromi; Michibayashi, Katsuyoshi; Ishii, Teruaki; Stern, Robert J.; Pujana, Ignacio; Martinez, Fernando; Girard, Guillaume; Ribeiro, Julia; Brounce, Maryjo; Komori, Naoaki; Kino, Masashi

2012-02-01

Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures and vent communities occur in different tectonic settings. The discovery of the Lost City hydrothermal field in the Mid-Atlantic Ridge has stimulated interest in the role of serpentinization of peridotite in generating H2- and CH4-rich fluids and associated carbonate chimneys, as well as in the biological communities supported in highly reduced, alkaline environments. Abundant vesicomyid clam communities associated with a serpentinite-hosted hydrothermal vent system in the southern Mariana forearc were discovered during a DSV Shinkai 6500 dive in September 2010. We named this system the "Shinkai Seep Field (SSF)." The SSF appears to be a serpentinite-hosted ecosystem within a forearc (convergent margin) setting that is supported by fault-controlled fluid pathways connected to the decollement of the subducting slab. The discovery of the SSF supports the prediction that serpentinite-hosted vents may be widespread on the ocean floor. The discovery further indicates that these serpentinite-hosted low-temperature fluid vents can sustain high-biomass communities and has implications for the chemical budget of the oceans and the distribution of abyssal chemosynthetic life.

A serpentinite-hosted ecosystem in the Southern Mariana Forearc

PubMed Central

Ohara, Yasuhiko; Reagan, Mark K.; Fujikura, Katsunori; Watanabe, Hiromi; Michibayashi, Katsuyoshi; Ishii, Teruaki; Stern, Robert J.; Pujana, Ignacio; Martinez, Fernando; Girard, Guillaume; Ribeiro, Julia; Brounce, Maryjo; Komori, Naoaki; Kino, Masashi

2012-01-01

Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures and vent communities occur in different tectonic settings. The discovery of the Lost City hydrothermal field in the Mid-Atlantic Ridge has stimulated interest in the role of serpentinization of peridotite in generating H2- and CH4-rich fluids and associated carbonate chimneys, as well as in the biological communities supported in highly reduced, alkaline environments. Abundant vesicomyid clam communities associated with a serpentinite-hosted hydrothermal vent system in the southern Mariana forearc were discovered during a DSV Shinkai 6500 dive in September 2010. We named this system the “Shinkai Seep Field (SSF).” The SSF appears to be a serpentinite-hosted ecosystem within a forearc (convergent margin) setting that is supported by fault-controlled fluid pathways connected to the decollement of the subducting slab. The discovery of the SSF supports the prediction that serpentinite-hosted vents may be widespread on the ocean floor. The discovery further indicates that these serpentinite-hosted low-temperature fluid vents can sustain high-biomass communities and has implications for the chemical budget of the oceans and the distribution of abyssal chemosynthetic life. PMID:22323611

A serpentinite-hosted ecosystem in the Southern Mariana Forearc.

PubMed

Ohara, Yasuhiko; Reagan, Mark K; Fujikura, Katsunori; Watanabe, Hiromi; Michibayashi, Katsuyoshi; Ishii, Teruaki; Stern, Robert J; Pujana, Ignacio; Martinez, Fernando; Girard, Guillaume; Ribeiro, Julia; Brounce, Maryjo; Komori, Naoaki; Kino, Masashi

2012-02-21

Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures and vent communities occur in different tectonic settings. The discovery of the Lost City hydrothermal field in the Mid-Atlantic Ridge has stimulated interest in the role of serpentinization of peridotite in generating H(2)- and CH(4)-rich fluids and associated carbonate chimneys, as well as in the biological communities supported in highly reduced, alkaline environments. Abundant vesicomyid clam communities associated with a serpentinite-hosted hydrothermal vent system in the southern Mariana forearc were discovered during a DSV Shinkai 6500 dive in September 2010. We named this system the "Shinkai Seep Field (SSF)." The SSF appears to be a serpentinite-hosted ecosystem within a forearc (convergent margin) setting that is supported by fault-controlled fluid pathways connected to the decollement of the subducting slab. The discovery of the SSF supports the prediction that serpentinite-hosted vents may be widespread on the ocean floor. The discovery further indicates that these serpentinite-hosted low-temperature fluid vents can sustain high-biomass communities and has implications for the chemical budget of the oceans and the distribution of abyssal chemosynthetic life.

Three-Dimensional Seismic Structure of the Mid-Atlantic Ridge: An Investigation of Tectonic, Magmatic, and Hydrothermal Processes in the Rainbow Area

NASA Astrophysics Data System (ADS)

Dunn, Robert A.; Arai, Ryuta; Eason, Deborah E.; Canales, J. Pablo; Sohn, Robert A.

2017-12-01

To test models of tectonic, magmatic, and hydrothermal processes along slow-spreading mid-ocean ridges, we analyzed seismic refraction data from the Mid-Atlantic Ridge INtegrated Experiments at Rainbow (MARINER) seismic and geophysical mapping experiment. Centered at the Rainbow area of the Mid-Atlantic Ridge (36°14'N), this study examines a section of ridge with volcanically active segments and a relatively amagmatic ridge offset that hosts the ultramafic Rainbow massif and its high-temperature hydrothermal vent field. Tomographic images of the crust and upper mantle show segment-scale variations in crustal structure, thickness, and the crust-mantle transition, which forms a vertical gradient rather than a sharp boundary. There is little definitive evidence for large regions of sustained high temperatures and melt in the lower crust or upper mantle along the ridge axes, suggesting that melts rising from the mantle intrude as small intermittent magma bodies at crustal and subcrustal levels. The images reveal large rotated crustal blocks, which extend to mantle depths in some places, corresponding to off-axis normal fault locations. Low velocities cap the Rainbow massif, suggesting an extensive near-surface alteration zone due to low-temperature fluid-rock reactions. Within the interior of the massif, seismic images suggest a mixture of peridotite and gabbroic intrusions, with little serpentinization. Here diffuse microearthquake activity indicates a brittle deformation regime supporting a broad network of cracks. Beneath the Rainbow hydrothermal vent field, fluid circulation is largely driven by the heat of small cooling melt bodies intruded into the base of the massif and channeled by the crack network and shallow faults.

The hydrothermal exploration system on the 'Qianlong2' AUV

NASA Astrophysics Data System (ADS)

Tao, W.; Tao, C.; Jinhui, Z.; Cai, L.; Guoyin, Z.

2016-12-01

ABSTRACT: Qianlong2, is a fully Autonomous Underwater Vehicle (AUV) designed for submarine resources research, especially for polymetallic sulphides, and the survey depths of is up to 4500 m. Qianlong2 had successfully explored hydrothermal vent field on the Southwest Indian Ridge (SWIR), and collected conductance, temperature and depth (CTD), turbidity, and Oxidation-Reduction Potential (ORP) data. It also had mapped precise topography by high resolution side scan sonar (HRBSSS) during every dive; and obtained photographs of sulfide deposits during some dives. Here, we detailedly described the implementation of investigation, data administration, and fast mapping of hydrothermal exploration system by Qianlong2. Giving a description of how to remove the platform magnetic interference by using magnetic data during Qianlong2 spin. Based on comprehensive hydrochemical anomalies, we get a rapid method for finding the localization of hydrothermal vents. Taking one dive as an example, we systemically showed the process about how to analyse hydrothermal survey data and acquire the location results of hydrothermal vents. Considering that this method is effective and can be used in other deep-submergence assets such as human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) during further studies. Finally, we discussed how to promote and optimize the installation and application of those sensors and how to improve Qianlong2's autonomy of investigation.

Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

NASA Astrophysics Data System (ADS)

Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

2016-10-01

Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline hydrothermal vents (Russell et al., 2014). Hydrothermal chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311-318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm. 51, 35: 7501-7504.

Modeling microbial reaction rates in a submarine hydrothermal vent chimney wall

NASA Astrophysics Data System (ADS)

LaRowe, Douglas E.; Dale, Andrew W.; Aguilera, David R.; L'Heureux, Ivan; Amend, Jan P.; Regnier, Pierre

2014-01-01

The fluids emanating from active submarine hydrothermal vent chimneys provide a window into subseafloor processes and, through mixing with seawater, are responsible for steep thermal and compositional gradients that provide the energetic basis for diverse biological communities. Although several models have been developed to better understand the dynamic interplay of seawater, hydrothermal fluid, minerals and microorganisms inside chimney walls, none provide a fully integrated approach to quantifying the biogeochemistry of these hydrothermal systems. In an effort to remedy this, a fully coupled biogeochemical reaction-transport model of a hydrothermal vent chimney has been developed that explicitly quantifies the rates of microbial catalysis while taking into account geochemical processes such as fluid flow, solute transport and oxidation-reduction reactions associated with fluid mixing as a function of temperature. The metabolisms included in the reaction network are methanogenesis, aerobic oxidation of hydrogen, sulfide and methane and sulfate reduction by hydrogen and methane. Model results indicate that microbial catalysis is generally fastest in the hottest habitable portion of the vent chimney (77-102 °C), and methane and sulfide oxidation peak near the seawater-side of the chimney. The fastest metabolisms are aerobic oxidation of H2 and sulfide and reduction of sulfate by H2 with maximum rates of 140, 900 and 800 pmol cm-3 d-1, respectively. The maximum rate of hydrogenotrophic methanogenesis is just under 0.03 pmol cm-3 d-1, the slowest of the metabolisms considered. Due to thermodynamic inhibition, there is no anaerobic oxidation of methane by sulfate (AOM). These simulations are consistent with vent chimney metabolic activity inferred from phylogenetic data reported in the literature. The model developed here provides a quantitative approach to describing the rates of biogeochemical transformations in hydrothermal systems and can be used to constrain the role of microbial activity in the deep subsurface.

The origin of life in alkaline hydrothermal vents

NASA Astrophysics Data System (ADS)

Sojo, V.; Herschy, B.; Whicher, A.; Camprubí, E.; Lane, N.

2016-12-01

The origin of life remains one of Science's greatest unresolved questions. The answer will no doubt involve almost all the basic disciplines, including Physics, Chemistry, Astronomy, Geology, and Biology. Chiefly, it is the link between the latter two that must be elucidated: how geochemistry gave rise to biochemistry. Serpentinizing systems such as alkaline hydrothermal vents offer the most robust combination of conditions to have hosted the origin of life on the early Earth, while bearing many parallels to modern living cells. Stark gradients of concentration, pH, oxidation/reduction, and temperature provided the ability to synthesise and concentrate organic products, drive polymerisation reactions, and develop an autotrophic lifestyle independent of foreign sources of organics. In the oxygen-depleted waters of the Hadean, alkaline vents would have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with the relatively acidic CO2-rich waters of the ocean, through interconnected micropores made of thin inorganic walls containing catalytic Fe(Ni)S minerals. Perhaps not coincidentally, the unit cells of these Fe(Ni)S minerals closely resemble the active sites of crucial ancestral bioenergetic enzymes. Meanwhile, differences in pH across the thin barriers produced natural proton gradients similar to those used for carbon fixation in modern archaea and bacteria. At the earliest stages, the problem of the origin of life is the problem of the origin of carbon fixation. I will discuss work over the last decade that suggests several possible hypotheses for how simple one-carbon molecules could have given rise to more complex organics, particularly within a serpentinizing alkaline hydrothermal vent. I will discuss the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria, thought to be the earliest representatives of each domain, to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, I will show that an origin of life in alkaline hydrothermal vents can explain the deep divergence in cell membranes and active ion pumping between archaea and bacteria, from a vent-bound last universal common ancestor (LUCA). Life's most puzzling traits may give a pointer to its origin.

A tribute to Peter A. Rona: A Russian Perspective

NASA Astrophysics Data System (ADS)

Sagalevich, Anatoly; Lutz, Richard A.

2015-11-01

In July 1985 Peter Rona led a cruise of the National Oceanic and Atmospheric Administration (NOAA) ship Researcher as part of the NOAA Vents Program and discovered, for the first time, black smokers, massive sulfide deposits and vent biota in the Atlantic Ocean. The site of the venting phenomena was the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the east wall of the rift valley of the Mid-Atlantic Ridge at 26°08‧N; 44°50‧W (Rona, 1985; Rona et al., 1986). In 1986, Peter and an international research team carried out multidisciplnary investigations of both active and inactive hydrothermal zones of the TAG field using the R/V Atlantis and DSV Alvin, discovering two new species of shrimp (Rimicaris exoculata and Chorocaris chacei) (Williams and Rona, 1986) and a hexagonal-shaped form (Paleodictyon nodosum) thought to be extinct (Rona et al., 2009). In 1991 a Russian crew aboard the R/V Akademik Mstislav Keldysh, with two deep-diving, human-occupied submersibles (Mir-1 and Mir-2) (Fig. 1), had the honor of having Peter Rona and a Canadian IMAX film crew from the Stephen Low Company on board to visit the TAG hydrothermal vent field. This was the first of many deep-sea interactions between Russian deep-sea scientists and their colleagues from both the U.S. and Canada. This expedition to the TAG site was part of a major Russian undersea program aimed at exploring extreme deep-sea environments; between 1988 and 2005, the Mir submersibles visited hydrothermal vents and cold seep areas in 20 deep-sea regions throughout the world's oceans (Sagalevich, 2002). Images of several of these areas (the TAG, Snake Pit, Lost City and 9°50‧N vent fields) were obtained using an IMAX camera system emplaced for the first time within the spheres of the Mir submersibles and DSV Alvin in conjunction with the filming of science documentaries (e.g., ;Volcanoes of the Deep Sea;) produced by the Stephen Low Company in conjunction with Emory Kristof of National Geographic and Peter Rona. The initial test of this submersible-emplaced camera system was conducted during the 1991 expedition to the TAG hydrothermal vent field.

The Sound Generated by Mid-Ocean Ridge Black Smoker Hydrothermal Vents

PubMed Central

Crone, Timothy J.; Wilcock, William S.D.; Barclay, Andrew H.; Parsons, Jeffrey D.

2006-01-01

Hydrothermal flow through seafloor black smoker vents is typically turbulent and vigorous, with speeds often exceeding 1 m/s. Although theory predicts that these flows will generate sound, the prevailing view has been that black smokers are essentially silent. Here we present the first unambiguous field recordings showing that these vents radiate significant acoustic energy. The sounds contain a broadband component and narrowband tones which are indicative of resonance. The amplitude of the broadband component shows tidal modulation which is indicative of discharge rate variations related to the mechanics of tidal loading. Vent sounds will provide researchers with new ways to study flow through sulfide structures, and may provide some local organisms with behavioral or navigational cues. PMID:17205137

Biological and environmental rhythms in (dark) deep-sea hydrothermal ecosystems

NASA Astrophysics Data System (ADS)

Cuvelier, Daphne; Legendre, Pierre; Laës-Huon, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée

2017-06-01

During 2011, two deep-sea observatories focusing on hydrothermal vent ecology were up and running in the Atlantic (Eiffel Tower, Lucky Strike vent field) and the Northeast Pacific Ocean (NEP) (Grotto, Main Endeavour Field). Both ecological modules recorded imagery and environmental variables jointly for a time span of 23 days (7-30 October 2011) and environmental variables for up to 9 months (October 2011-June 2012). Community dynamics were assessed based on imagery analysis and rhythms in temporal variation for both fauna and environment were revealed. Tidal rhythms were found to be at play in the two settings and were most visible in temperature and tubeworm appearances (at NEP). A ˜ 6 h lag in tidal rhythm occurrence was observed between Pacific and Atlantic hydrothermal vents, which corresponds to the geographical distance and time delay between the two sites.

Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge.

USGS Publications Warehouse

Philpotts, J.A.; Aruscavage, P. J.; Von Damm, Karen L.

1987-01-01

Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from 7 vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low.-from Authors

Microbial diversity in hydrothermal surface to subsurface environments of Suiyo Seamount, Izu-Bonin Arc, using a catheter-type in situ growth chamber.

PubMed

Higashi, Yowsuke; Sunamura, Michinari; Kitamura, Keiko; Nakamura, Ko-ichi; Kurusu, Yasurou; Ishibashi, Jun-ichiro; Urabe, Tetsuro; Maruyama, Akihiko

2004-03-01

After excavation using a portable submarine driller near deep-sea hydrothermal vents in the Suiyo Seamount, Izu-Bonin Arc, microbial diversity was examined in samples collected from inside the boreholes using an in situ growth chamber called a vent catheter. This instrument, which we devised for this study, consists of a heat-tolerant pipe tipped with a titanium mesh entrapment capsule that is packed with sterilized inorganic porous grains, which serve as an adhesion substrate. After this instrument was deployed inside each of the boreholes, as well as a natural vent, for 3-10 days in the vicinity of hot vent fluids (maxima: 156-305 degrees C), DNA was extracted from the adhesion grains, 16S rDNA was amplified, and randomly selected clones were sequenced. In phylogenetic analysis of more than 120 clones, several novel phylotypes were detected within the epsilon-Proteobacteria, photosynthetic bacteria (PSB)-related alpha-Proteobacteria, and Euryarchaeota clusters. Members of epsilon-Proteobacteria were frequently encountered. Half of these were classified between two known groups, Corre's B and D. The other half of the clones were assigned to new groups, SSSV-BE1 and SSSV-BE2 (Suiyo Seamount sub-vent origin, Bacteria domain, epsilon-Proteobacteria, groups 1 and 2). From this hydrothermal vent field, we detected a novel lineage within the PSB cluster, SSNV-BA1 (Suiyo Seamount natural vent origin, Bacteria domain, alpha-Proteobacteria, group 1), which is closely related to Rhodopila globiformis isolated from a hot spring. A number of archaeal clones were also detected from the borehole samples. These clones formed a novel monophyletic clade, SSSV-AE1 (Suiyo Seamount sub-vent origin, Archaea domain, Euryarchaeota, group 1), approximately between methanogenic hyperthermophilic members of Methanococcales and environmental clone members of DHVE Group II. Thus, this hydrothermal vent environment appears to be a noteworthy microbial and genetic resource. It is also noteworthy that some of the findings presented here were made possible by the application of the in situ growth chamber into the hot fluids deep inside the boreholes.

Propagation of vent CO2 in a subtropical shallow-water ecosystem assessed by stable carbon isotopes

NASA Astrophysics Data System (ADS)

Cheng, Y. F.; Chen, C. T. A.; Liao, Y. M.; Lin, Y. S.

2016-02-01

Carbon cycle of the ocean plays an important role in the global change associated with the emission of CO2. Anthropogenic CO2 dissolves in seawater, changes carbon chemistry of the ocean, and affects marine life in different and complicated ways. In this study, we investigated stable carbon isotope systematics of a shallow-water hydrothermal field near the Kueishantao Islet off NE Taiwan, which has vent gas composition dominated by CO2 and world record breaking low pH hydrothermal fluids. By studying this natural laboratory of ocean acidification, we aim at clarifying to which extent the high dosage of CO2 propagates in the subtropical shallow-water ecosystem, and how it affects the carbon cycle. Samples of seawater and suspended particles were collected from stations of two nearshore-offshore transects, one with hydrothermal vents at the nearshore end (Transect M, 1230 m long) and the other serving as the baseline (Transect B, 1560 m long). Surface seawater of Transect M showed increasing pH in the offshore direction, from 5.8 at the vent mouths to 7.6 at the most distant station. In contrast, pH of surface water decreased seaward from 8.0 to 7.8 in Transect B. The δ13C values of the vent CO2 averaged -6.4‰, consistent with the range attributed to mantle CO2. Seawater DIC δ13C values of Transect M were 13C-depleted (as negative as -2.5‰) at the vent mouths, and became increasingly 13C-enriched till 0.7‰ at the most distant station. This pattern is in clear contrast to that of Transect B, the DIC δ13C values of which decreased from 0.7 to 0.6 ‰ in the offshore direction. We concluded that the vent CO2 has propagated in the surface ocean at least >700 m away from the hydrothermal field. Our next step is to explore how the vent CO2 affects the stable carbon isotopes of particulate organic matter, and to assess the effect of vent CO2 using quantitative approaches.

Hydrothermal and Chemosynthetic Ecosystems in the Southern Ocean: Current Knowledge on their Biology Paper 217790

NASA Astrophysics Data System (ADS)

Linse, K.; Rogers, A. D.; Bohrmann, G.; Copley, J.; Tyler, P. A.

2017-12-01

The existence of hydrothermal and other chemosynthetic ecosystems is not surprising in the Antarctic, with its active volcanoes, mid-ocean ridges and back-arc basins, and abundance of marine mammals. In the last two decades a variety of active chemosynthetic ecosystems have been discovered in the Southern Ocean, including low- and high-temperature hydrothermal vents, methane seeps, and whalefalls. Here a summary of the data from the known chemosynthetic communites will be presented, comparing the faunas of vent sites in the Bransfield Strait with those of the East Scotia Ridge (ESR) and the South Sandwich Arc, assessing the fauna at the South Georgia methane seep sites, and discussing the fauna on Antarctic whale falls. As the faunal assemblages of the ESR vents are the most studied in detail to date, this talk therefore focusses on the diversity and composition of the ESR macrofaunal assemblages, their foodweb structure and microdistributions in relation to fluid chemistry and microbiology, and their phylogenetic and biogeographic relationships. The Southern Ocean drives the global ocean conveyor belt, and is suggested to be the centre of origin for global deep-sea fauna, as well as a region of high deep-sea species diversity. In the context of chemosynthetic environments, it may provide a gateway connecting the global vent and seep systems. The mostly endemic species of Southern Ocean vent macrofauna show links to either one or more oceans (Atlantic, Indian, and Pacific), with some evidence for circum-Antarctic connection. The ESR species Gigantopelta chessoia, Kiwa tyleri and Vulcanolepas scotiaensis have their closest known relatives at the Longqi Vent Field on the Southwest Indian Ridge (SWIR), and one species of polynoid polychaete is known from ESR and SWIR vents. Meanwhile, Lepetdrilus sp. and a vesiocomyid clam are linked with species in the Atlantic vent fields. The stichasterid Paulasterias tyleri, the polychaete Rarricirrus jennae and the anthozoan Relicanthus daphneae have close molecular genetic links with North-eastern Pacific chemosynthetics sites. The presence of Paulasterias tyleri at vent fields (ESR & AAR) and in the Ross Sea could indicate further active hydrothermal sites with associated chemosysthetic ecosystems there and potentially in other Antarctic regions.

Organic Biomarker Preservation in Silica-Rich Hydrothermal Systems with Implications to Mars

NASA Astrophysics Data System (ADS)

Jahnke, L. L.; Parenteau, M. N.; Farmer, J. D.

2016-05-01

Microbial community structure and preservation of organic matter in siliceous hydrothermal environments is a critical issue given the discovery of hydrothermal vents and silica on Mars. Here we discuss preservation of cyanobacterial biomarker lipid.

Highly sensitive avoidance plays a key role in sensory adaptation to deep-sea hydrothermal vent environments.

PubMed

Ogino, Tetsuya; Maegawa, Shingo; Shigeno, Shuichi; Fujikura, Katsunori; Toyohara, Haruhiko

2018-01-01

The environments around deep-sea hydrothermal vents are very harsh conditions for organisms due to the possibility of exposure to highly toxic compounds and extremely hot venting there. Despite such extreme environments, some indigenous species have thrived there. Alvinellid worms (Annelida) are among the organisms best adapted to high-temperature and oxidatively stressful venting regions. Although intensive studies of the adaptation of these worms to the environments of hydrothermal vents have been made, little is known about the worms' sensory adaptation to the severe chemical conditions there. To examine the sensitivity of the vent-endemic worm Paralvinella hessleri to low pH and oxidative stress, we determined the concentration of acetic acid and hydrogen peroxide that induced avoidance behavior of this worm, and compared these concentrations to those obtained for related species inhabiting intertidal zones, Thelepus sp. The concentrations of the chemicals that induced avoidance behavior of P. hessleri were 10-100 times lower than those for Thelepus sp. To identify the receptors for these chemicals, chemical avoidance tests were performed with the addition of ruthenium red, a blocker of transient receptor potential (TRP) channels. This treatment suppressed the chemical avoidance behavior of P. hessleri, which suggests that TRP channels are involved in the chemical avoidance behavior of this species. Our results revealed for the first time hypersensitive detection systems for acid and for oxidative stress in the vent-endemic worm P. hessleri, possibly mediated by TRP channels, suggesting that such sensory systems may have facilitated the adaptation of this organism to harsh vent environments.

Chemical environments of submarine hydrothermal systems

NASA Technical Reports Server (NTRS)

Shock, Everett L.

1992-01-01

Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

Biogeochemical Cycling of Manganese at Hydrothermal Vents

DTIC Science & Technology

1990-01-01

from an anoxic basin) contain the gene for the large subunit of Ribulose- 1,5-bisphosphate Carboxylase Oxygenase ( RubisCO ) suggestive of autotrophy... RubisCO gene probing on the bacterial isolates obtained from the hydrothermal vent environments as part of an ongoing ONR contract. In addition, we have...to test the feasibility of using gene probes for Ribulose-l,5- bisphosphate Carboxylase Oxygenase ( RubisCO ) for identifying autotrophic Mn(II

Subseafloor microbial communities in hydrogen-rich vent fluids from hydrothermal systems along the Mid-Cayman Rise.

PubMed

Reveillaud, Julie; Reddington, Emily; McDermott, Jill; Algar, Christopher; Meyer, Julie L; Sylva, Sean; Seewald, Jeffrey; German, Christopher R; Huber, Julie A

2016-06-01

Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition, diversity, and function of microbes in venting fluids from both sites: Piccard, the world's deepest vent site, hosted in mafic rocks; and Von Damm, an adjacent, ultramafic-influenced system. Von Damm hosted a wider diversity of lineages and metabolisms in comparison to Piccard, consistent with thermodynamic models that predict more numerous energy sources at ultramafic systems. There was little overlap in the phylotypes found at each site, although similar and dominant hydrogen-utilizing genera were present at both. Despite the differences in community structure, depth, geology, and fluid chemistry, energetic modelling and metagenomic analysis indicate near functional equivalence between Von Damm and Piccard, likely driven by the high hydrogen concentrations and elevated temperatures at both sites. Results are compared with hydrothermal sites worldwide to provide a global perspective on the distinctiveness of these newly discovered sites and the interplay among rocks, fluid composition and life in the subseafloor. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Loki's Castle: Discovery and geology of a black smoker vent field at the Arctic Mid-Ocean Ridge

NASA Astrophysics Data System (ADS)

Pedersen, R.; Thorseth, I. H.; Lilley, M. D.; Barriga, F. J.; Früh-Green, G.; Nakamura, K.

2010-12-01

Previous attempts to locate hydrothermal vent fields and unravel the nature of venting at the ultraslow spreading and magma starved parts of the Arctic Mid Ocean Ridge (AMOR) have been unsuccessful. A black smoker vent field was eventually discovered at the Mohns-Knipovich bend at 73.5°N in 2008, and the field was revisited in 2009 and 2010. The Loki’s Castle vent field is located on the crest of an axial volcanic ridge that is bordered by a tectonic terrain dominated by core complexes to the NW, and a ridge flank that is buried by sediments from the Bear Island Fan to the SE. Fluid compositions are anomalous to other basalt-hosted fields and indicate interactions with sediments at depths. The vent field is associated with an unusually large hydrothermal deposit, which documents that extensive venting occurs at ultraslow spreading ridges despite the strongly reduced magmatic heat budget. ROV surveys have shown that venting occurs in two areas separated by around 100 m. Micro-bathymetry acquired by a Hugin AUV documents that two 20-30 tall mounds that coalesce at the base have developed around the vent sites. The micro-bathymetry also shows that the venting is located above two normal faults that define the NW margin of a rift that runs along the crest of the volcano. The black smoker fluids reach 317 °C, with an end-member SiO2 content of 16 mmol/kg. End-member chlorinity is around 85% of seawater suggesting that the fluids have phase-separated at depth. The fluid compositions indicate that the rock-water reactions occur around 2 km below the seafloor. The crustal thickness is estimated to be 4 +/- 0.5 km in the area. Whereas the depth of the reaction zone is comparable with faster spreading ridges, the fraction of crust cooled convectively by hydrothermal circulation is two times that of vent fields at ridges with normal crustal thickness.

Discovery of Nascent Vents and Recent Colonization Associated with(Re)activated Hydrothermal Vent Fields by the GALREX 2011 Expedition on the Galápagos Rift

NASA Astrophysics Data System (ADS)

Shank, T. M.; Holden, J. F.; Herrera, S.; Munro, C.; Muric, T.; Lin, J.; Stuart, L.

2011-12-01

GALREX 2011 was a NOAA OER telepresence cruise that explored the diverse habitats and geologic settings of the deep Galápagos region. The expedition made12 Little Hercules ROV dives in July 2011.Abundant corals and a strong depth zonation of species (including deepwater coral communities) were found near 500 m depth on Paramount Seamount, likely influenced by past low sea level states, wave-cut terrace processes, and the historical presence of shallow reef structures. At fresh lava flows with associated (flocculent) hydrothermal venting near 88° W, now known as Uka Pacha and Pegasus Vent Fields, rocks were coated with white microbial mat and lacked sessile fauna, with few mobile fauna (e.g., bythograeid crabs, alvinocarid shrimp, polynoid worms, zoarcid fish, and dirivultid copepods). This suggests a recent creation of hydrothermal habitats through volcanic eruptions and/or diking events, which may have taken place over a 15 km span separating the two vent fields. The Rosebud vent field at 86°W was not observed and may have been covered with lava since last visited in 2005. A hydrothermal vent field near 86°W was discovered that is one of the largest vent fields known on the Rift (120m by 40m). Low-temperature vent habitats were colonized by low numbers of tubeworms including Riftia, Oasisia, and a potential Tevnia species (the latter not previously observed on the Galapagos Rift). Patches of tubeworms were observed with individuals less than 2cm in length, and the relatively few large Riftia had tube lengths near 70cm long. Large numbers of small (< 3cm long) bathymodiolin mussels lined cracks and crevices throughout the active part of the field. Live clams, at least four species of gastropod limpets, three species of polynoid polychaetes, juvenile and adult alvinocarid shrimp, actinostolid anemones, and white microbial communities were observed on the underside and vertical surfaces of basalt rock surfaces. There were at least 13 species of vent-endemic fauna. The active colonization was observed on relatively older basalt pillows and lobate lavas ringed by and amidst a large dead bed of Calyptogena clams (most with broken and dissolving shells greater than 25 cm in length, with a few of the same size living amongst the dissolving shells). Scattered pockets of living adult mussels were observed among these dead clams. The margins of the field were ringed with large numbers of dandelion siphonophores. This field, named Tempus Fugit Vent Field, was once a massive clam bed (> 20 years old) and now, while hosting mature mussel communities and adult clams (> 2 years old), is being actively colonized by vent-endemic fauna that can be considered to be recent arrivals and colonizers (less than a few months) at Galapagos vent fields. These findings not only provide strong evidence of recent volcanic activity between 85° W and 88° W on the Galapagos Rift, but provide evidence that the rates of hydrothermal habitat turnover via eruption, dike injection, or venting cessation may be considerably higher than previously thought along the Galápagos Rift.

Constrained circulation at Endeavour ridge facilitates colonization by vent larvae.

PubMed

Thomson, Richard E; Mihály, Steven F; Rabinovich, Alexander B; McDuff, Russell E; Veirs, Scott R; Stahr, Frederick R

2003-07-31

Understanding how larvae from extant hydrothermal vent fields colonize neighbouring regions of the mid-ocean ridge system remains a major challenge in oceanic research. Among the factors considered important in the recruitment of deep-sea larvae are metabolic lifespan, the connectivity of the seafloor topography, and the characteristics of the currents. Here we use current velocity measurements from Endeavour ridge to examine the role of topographically constrained circulation on larval transport along-ridge. We show that the dominant tidal and wind-generated currents in the region are strongly attenuated within the rift valley that splits the ridge crest, and that hydrothermal plumes rising from vent fields in the valley drive a steady near-bottom inflow within the valley. Extrapolation of these findings suggests that the suppression of oscillatory currents within rift valleys of mid-ocean ridges shields larvae from cross-axis dispersal into the inhospitable deep ocean. This effect, augmented by plume-driven circulation within rift valleys having active hydrothermal venting, helps retain larvae near their source. Larvae are then exported preferentially down-ridge during regional flow events that intermittently over-ride the currents within the valley.

Adventive hydrothermal circulation on Stromboli volcano (Aeolian Islands, Italy) revealed by geophysical and geochemical approaches: Implications for general fluid flow models on volcanoes

NASA Astrophysics Data System (ADS)

Finizola, A.; Ricci, T.; Deiana, R.; Cabusson, S. Barde; Rossi, M.; Praticelli, N.; Giocoli, A.; Romano, G.; Delcher, E.; Suski, B.; Revil, A.; Menny, P.; Di Gangi, F.; Letort, J.; Peltier, A.; Villasante-Marcos, V.; Douillet, G.; Avard, G.; Lelli, M.

2010-09-01

On March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products, mostly lithic blocks, some of which impacted the ground as far as down to 200 m a.s.l., about 1.5 km far away from the active vents. Two days after the explosion, a new vapour emission was discovered on the north-eastern flank of the volcanic edifice, at 560 m a.s.l., just above the area called "Nel Cannestrà". This new vapour emission was due to a block impact. In order to investigate the block impact area to understand the appearance of the vapour emission, we conducted on May 2008 a multidisciplinary study involving Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Self-Potential (SP), CO 2 soil diffuse degassing and soil temperature surveys. This complementary data set revealed the presence of an anomalous conductive body, probably related to a shallow hydrothermal level, at about 10-15 m depth, more or less parallel to the topography. It is the first time that such a hydrothermal fluid flow, with a temperature close to the water boiling point (76 °C) has been evidenced at Stromboli at this low elevation on the flank of the edifice. The ERT results suggest a possible link between (1) the main central hydrothermal system of Stromboli, located just above the plumbing system feeding the active vents, with a maximum of subsurface soil temperature close to 90 °C and limited by the NeoStromboli summit crater boundary and (2) the investigated area of Nel Cannestrà, at ~ 500 m a.s.l., a buried eruptive fissure active 9 ka ago. In parallel, SP and CO 2 soil diffuse degassing measurements suggest in this sector at slightly lower elevation from the block impact crater a magmatic and hydrothermal fluid rising system along the N41° regional fault. A complementary ERT profile, on May 2009, carried out from the NeoStromboli crater boundary down to the block impact crater displayed a flank fluid flow apparently connected to a deeper system. The concept of shallow hydrothermal level have been compared to similar ERT results recently obtained on Mount Etna and La Fossa cone of Vulcano. This information needs to be taken into account in general fluid flow models on volcanoes. In particular, peripheral thermal waters (as those bordering the north-eastern coast of Stromboli) could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit.

Geobiology of Marine Magnetotactic Bacteria

DTIC Science & Technology

2006-06-01

acids (e.g. lactate, acetate, oxalate , succinate, fumarate, malate, and citrate) which are continually transported into the soil, in part due to the...microbial mats, and hydrothermal vent waters. J Environ Monit 3: 61-66. 177 Lyons TW (1997) Sulfur isotopic trends and pathways of iron sulfide formation in...case in sediments, microbial mats, and hydrothermal vent waters. J Environ Monit 3: 61-66. 200 O’Sullivan DW, Hanson Jr AK, Kester DR (1997) The

A novel hydrogen oxidizer amidst the sulfur-oxidizing Thiomicrospira lineage

PubMed Central

Hansen, Moritz; Perner, Mirjam

2015-01-01

Thiomicrospira species are ubiquitously found in various marine environments and appear particularly common in hydrothermal vent systems. Members of this lineage are commonly classified as sulfur-oxidizing chemolithoautotrophs. Although sequencing of Thiomicrospira crunogena's genome has revealed genes that encode enzymes for hydrogen uptake activity and for hydrogenase maturation and assembly, hydrogen uptake ability has so far not been reported for any Thiomicrospira species. We isolated a Thiomicrospira species (SP-41) from a deep sea hydrothermal vent and demonstrated that it can oxidize hydrogen. We show in vivo hydrogen consumption, hydrogen uptake activity in partially purified protein extracts and transcript abundance of hydrogenases during different growth stages. The ability of this strain to oxidize hydrogen opens up new perspectives with respect to the physiology of Thiomicrospira species that have been detected in hydrothermal vents and that have so far been exclusively associated with sulfur oxidation. PMID:25226028

Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor

PubMed Central

Yanagawa, Katsunori; Ijiri, Akira; Breuker, Anja; Sakai, Sanae; Miyoshi, Youko; Kawagucci, Shinsuke; Noguchi, Takuroh; Hirai, Miho; Schippers, Axel; Ishibashi, Jun-ichiro; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2017-01-01

Subseafloor microbes beneath active hydrothermal vents are thought to live near the upper temperature limit for life on Earth. We drilled and cored the Iheya North hydrothermal field in the Mid-Okinawa Trough, and examined the phylogenetic compositions and the products of metabolic functions of sub-vent microbial communities. We detected microbial cells, metabolic activities and molecular signatures only in the shallow sediments down to 15.8 m below the seafloor at a moderately distant drilling site from the active hydrothermal vents (450 m). At the drilling site, the profiles of methane and sulfate concentrations and the δ13C and δD isotopic compositions of methane suggested the laterally flowing hydrothermal fluids and the in situ microbial anaerobic methane oxidation. In situ measurements during the drilling constrain the current bottom temperature of the microbially habitable zone to ~45 °C. However, in the past, higher temperatures of 106–198 °C were possible at the depth, as estimated from geochemical thermometry on hydrothermally altered clay minerals. The 16S rRNA gene phylotypes found in the deepest habitable zone are related to those of thermophiles, although sequences typical of known hyperthermophilic microbes were absent from the entire core. Overall our results shed new light on the distribution and composition of the boundary microbial community close to the high-temperature limit for habitability in the subseafloor environment of a hydrothermal field. PMID:27754478

Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor.

PubMed

Yanagawa, Katsunori; Ijiri, Akira; Breuker, Anja; Sakai, Sanae; Miyoshi, Youko; Kawagucci, Shinsuke; Noguchi, Takuroh; Hirai, Miho; Schippers, Axel; Ishibashi, Jun-Ichiro; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2017-02-01

Subseafloor microbes beneath active hydrothermal vents are thought to live near the upper temperature limit for life on Earth. We drilled and cored the Iheya North hydrothermal field in the Mid-Okinawa Trough, and examined the phylogenetic compositions and the products of metabolic functions of sub-vent microbial communities. We detected microbial cells, metabolic activities and molecular signatures only in the shallow sediments down to 15.8 m below the seafloor at a moderately distant drilling site from the active hydrothermal vents (450 m). At the drilling site, the profiles of methane and sulfate concentrations and the δ 13 C and δD isotopic compositions of methane suggested the laterally flowing hydrothermal fluids and the in situ microbial anaerobic methane oxidation. In situ measurements during the drilling constrain the current bottom temperature of the microbially habitable zone to ~45 °C. However, in the past, higher temperatures of 106-198 °C were possible at the depth, as estimated from geochemical thermometry on hydrothermally altered clay minerals. The 16S rRNA gene phylotypes found in the deepest habitable zone are related to those of thermophiles, although sequences typical of known hyperthermophilic microbes were absent from the entire core. Overall our results shed new light on the distribution and composition of the boundary microbial community close to the high-temperature limit for habitability in the subseafloor environment of a hydrothermal field.

Rare Earth Element Concentrations in Submarine Hydrothermal Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in submarine hydrothermal fluids from Alarcon Rise, East Pacific Rise, REE concentrations in submarine hydrothermal fluids from Pescadero Basin, Gulf of California, and the Cleft vent field, southern Juan de Fuca Ridge. Data are not corrected to zero Mg.

Seabed deposits classification at the Precious Stone Mountain hydrothermal field using MultiBeam sonar data

NASA Astrophysics Data System (ADS)

Tao, C.; Zhang, G.; Li, H.; Zhou, J.; Liu, W.; Deng, X.; Chen, S.

2013-12-01

The seabed deposits type and distribution are very complex at the hydrothermal field. In this paper, we provided an approach to study the seabed deposits classification at the Precious Stone Mountain hydrothermal field (PSMHF) using MultiBeam sonar data (Figure 1). The PSMHF was found in the Galapogas microplate at the Leg 3 of the Chinese COMRA 21st Cruise. Using this approach, the seabed deposits at the PSMHF are mainly classified into three types, which are rock, breccia and sediment, respectively. We can find the distribution of the three types of seabed deposits according to the sonar back-scattering data. The rocks are mostly distributed around the hydrothermal vent. The breccia are located at the foot of the vent. Most sediments are distributed at the southwest to the vent due to bottom current. Combining with seabed video, TV-Grab sample and the backscatter data, we draw the map of the seabed deposits distribution at the PSMHF (Figure 2). Figure 1 The flow chart of the seabed deposits classification approach Figure 2 The seabed deposits distribution of the PSMHF

Geologic form and setting of a hydrothermal vent field at lat 10°56‧N, East Pacific Rise: A detailed study using Angus and Alvin

NASA Astrophysics Data System (ADS)

McConachy, T. F.; Ballard, R. D.; Mottl, M. J.; von Herzen, R. P.

1986-04-01

A hydrothermal vent field, here called the Feather Duster site, occurs on the eastern marginal high near the edge of a narrow (95-m) and shallow (15 20-m) axial graben, within an area dominated by sheet flows and collapse features. The sheet flows are intermediate in relative age between younger fluid-flow lavas on the floor of the axial graben and older pillow (constructional) lavas on the marginal highs. Hydrothermal activity occurs in two zones within a 65 by 45 m area. The main zone is located where a fissure system and sulfide-sulfate chimneys vent warm (9 47 °C) and hot (347 °C) hydrothermal fluids. Here, two mounds of massive sulfide totaling about 200 t are forming. One occurs at the base of a 3-m-high scarp which is the wall of a drained lava lake; the other is perched on top of the scarp. *Present address: Department of Geology, University of Toronto, Toronto, Ontario, Canada M5S 1A1

Metal concentrations in the tissues of the hydrothermal vent mussel Bathymodiolus: reflection of different metal sources.

PubMed

Koschinsky, Andrea; Kausch, Matteo; Borowski, Christian

2014-04-01

Hydrothermal vent mussels of the genus Bathymodiolus are ideally positioned for the use of recording hydrothermal fluxes at the hydrothermal vent sites they inhabit. Barium, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Pb, Sr, and U concentrations in tissue sections of Bathymodiolus mussels from several hydrothermal fields between 15°N and 9°S at the Mid-Atlantic Ridge were determined and compared to the surrounding fluids and solid substrates in the habitats. Elements generally enriched in hydrothermal fluids, such as Fe, Cu, Zn, Pb and Cd, were significantly enriched in the gills and digestive glands of the hydrothermal mussels. The rather small variability of Zn (and Mn) and positive correlation with K and earth alkaline metals may indicate a biological regulation of accumulation. Enrichments of Mo and U in many tissue samples indicate that particulate matter such as hydrothermal mineral particles from the plumes can play a more important role as a metal source than dissolved metals. Highest enrichments of Cu in mussels from the Golden Valley site indicate a relation to the ≥400 °C hot heavy-metal rich fluids emanating in the vicinity. In contrast, mussels from the low-temperature Lilliput field are affected by the Fe oxyhydroxide sediment of their habitat. In a comparison of two different sites within the Logatchev field metal distributions in the tissues reflected small-scale local variations in the metal content of the fluids and the particulate material. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Production of Methane, Hydrogen, and Organic Compounds in Ultramafic-Hosted Hydrothermal Vents of the Mid-Atlantic Ridge

PubMed Central

Charlou, J.L.; Holm, N.G.; Mousis, O.

2015-01-01

Abstract Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4 to the ocean. Although there are lines of evidence of their abiogenic formation from stable C and H isotope results, laboratory experiments, and thermodynamic data, neither their origin nor the reaction pathways generating these gases have been fully constrained yet. Organic compounds detected in the fluids may also be derived from abiotic reactions. Although thermodynamics are favorable and extensive experimental work has been done on Fischer-Tropsch-type reactions, for instance, nothing is clear yet about their origin and formation mechanism from actual data. Since chemolithotrophic microbial communities commonly colonize hydrothermal vents, biogenic and thermogenic processes are likely to contribute to the production of H2, CH4, and other organic compounds. There seems to be a consensus toward a mixed origin (both sources and processes) that is consistent with the ambiguous nature of the isotopic data. But the question that remains is, to what proportions? More systematic experiments as well as integrated geochemical approaches are needed to disentangle hydrothermal geochemistry. This understanding is of prime importance considering the implications of hydrothermal H2, CH4, and organic compounds for the ocean global budget, global cycles, and the origin of life. Key Words: Hydrogen—Methane—Organics—MAR—Abiotic synthesis—Serpentinization—Ultramafic-hosted hydrothermal vents. Astrobiology 15, 381–399. PMID:25984920

Archaeal Diversity and Distribution along Thermal and Geochemical Gradients in Hydrothermal Sediments at the Yonaguni Knoll IV Hydrothermal Field in the Southern Okinawa Trough▿ †

PubMed Central

Nunoura, Takuro; Oida, Hanako; Nakaseama, Miwako; Kosaka, Ayako; Ohkubo, Satoru B.; Kikuchi, Toru; Kazama, Hiromi; Hosoi-Tanabe, Shoko; Nakamura, Ko-ichi; Kinoshita, Masataka; Hirayama, Hisako; Inagaki, Fumio; Tsunogai, Urumu; Ishibashi, Jun-ichiro; Takai, Ken

2010-01-01

A variety of archaeal lineages have been identified using culture-independent molecular phylogenetic surveys of microbial habitats occurring in deep-sea hydrothermal environments such as chimney structures, sediments, vent emissions, and chemosynthetic macrofauna. With the exception of a few taxa, most of these archaea have not yet been cultivated, and their physiological and metabolic traits remain unclear. In this study, phylogenetic diversity and distribution profiles of the archaeal genes encoding small subunit (SSU) rRNA, methyl coenzyme A (CoA) reductase subunit A, and the ammonia monooxygenase large subunit were characterized in hydrothermally influenced sediments at the Yonaguni Knoll IV hydrothermal field in the Southern Okinawa Trough. Sediment cores were collected at distances of 0.5, 2, or 5 m from a vent emission (90°C). A moderate temperature gradient extends both horizontally and vertically (5 to 69°C), indicating the existence of moderate mixing between the hydrothermal fluid and the ambient sediment pore water. The mixing of reductive hot hydrothermal fluid and cold ambient sediment pore water establishes a wide spectrum of physical and chemical conditions in the microbial habitats that were investigated. Under these different physico-chemical conditions, variability in archaeal phylotype composition was observed. The relationship between the physical and chemical parameters and the archaeal phylotype composition provides important insight into the ecophysiological requirements of uncultivated archaeal lineages in deep-sea hydrothermal vent environments, giving clues for approximating culture conditions to be used in future culturing efforts. PMID:20023079

In-Situ pH Measurements in Mid-Ocean Ridge Hydrothermal Vent Fluids: Constraints on Subseafloor Alteration Processes at Crustal Depths

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Ding, K.; Seyfried, W. E.

2013-12-01

Developments in electrochemistry and material science have facilitated the construction of ceramic (YSZ) based chemical sensor systems that can be used to measure and monitor pH and redox in aqueous fluids at elevated temperatures and pressures. In recent years, these sensor systems have been deployed to acquire real-time and time series in-situ data for high-temperature hydrothermal vent fluids at the Main Endeavour Field (Juan de Fuca Ridge), 9oN (East Pacific Rise), and at the ultramafic-hosted Rainbow field (36oN, Mid-Atlantic Ridge). Here we review in-situ pH data measured at these sites and apply these data to estimate the pH of fluids ascending to the seafloor from hydrothermal alteration zones deeper in the crust. In general, in-situ pH measured at virtually all vent sites is well in excess of that measured shipboard owing to the effects of temperature on the distribution of aqueous species and the solubility of metal sulfides, especially Cu and Zn, originally dissolved in the vent fluids. In situ pH measurements determined at MEF (Sully vent) and EPR 9oN (P-vent) in 2005 and 2008 were 4.4 ×0.02 and 5.05×0.05, respectively. The temperature and pressure (seafloor) of the vent fluids at each of the respective sites were 356oC and 220 bar, and 380oC and 250 bar. Plotting these data with respect to fluid density reveals that the in-situ pH of each vent fluid is approximately 1.5 pH units below neutrality. The density-pH (in-situ) correlation, however, is important because it provides a means from which the vent fluids were derived. Using dissolved silica and chloride from fluid samples at the MEF (Sully) suggest T/P conditions of approximately 435oC, 380 bar, based on quartz-fluid and NaCl-H2O systems. At the fluid density calculated for these conditions, pH (in-situ) is predicted to be ~6.2. Attempts are presently underway to assess the effect of the calculated pH on metal sulfide and silicate (e.g., plagioclase, chlorite) solubility in comparison with constraints imposed by the full range of chemical components in the vent fluids sampled and analyzed in association with pH (in-situ) measurements. Since pH is a master variable in all geochemical systems, the novel approach proposed here may provide new insight on hydrothermal alteration processes at conditions difficult or impossible to assess by more traditional means, ultimately influencing hydrothermal fluid fluxes.

Sill induced hydrothermal venting: A summary of our current understanding

NASA Astrophysics Data System (ADS)

Jerram, Dougal; Svenesn, Henrik; Planke, Sverre; Millett, John; Reynolds, Pete

2017-04-01

Hydrothermal vent structures which are predominantly related with the emplacement of large (>1000 km3) intrusions into the sub-volcanic basins represent a specific style of piercement structure, where climate-forcing gases can be transferred into the atmosphere and hydrosphere. In this case, the types and volumes of gas produced by intrusions is heavily dependent on the host-rock sediment properties that they intrude through. The distribution of vent structures can be shown to be widespread in Large Igneous Provinces for example on both the Norwegian and the Greenland margins of the North Atlantic Igneous Province (NAIP). In this overview we assess the distribution, types and occurrence of hydrothermal vent structures associated with LIPs. There is particular focus on those within the NAIP using mapped examples from offshore seismic data as well as outcrop analogues, highlighting the variability of these structures and their deposits. As the availability of 3D data from offshore and onshore increases, the full nature of the volcanic stratigraphy from the subvolcanic intrusive complexes, through the main eruption cycles into the piercing vent structures, can be realised along the entirety of volcanic rifted margins and LIPs. This will help greatly in our understanding of the evolving palaeo-environments, and climate contributions during the evolution of these short lived massive volcanic events.

High Connectivity of Animal Populations in Deep-Sea Hydrothermal Vent Fields in the Central Indian Ridge Relevant to Its Geological Setting

PubMed Central

Beedessee, Girish; Watanabe, Hiromi; Ogura, Tomomi; Nemoto, Suguru; Yahagi, Takuya; Nakagawa, Satoshi; Nakamura, Kentaro; Takai, Ken; Koonjul, Meera; Marie, Daniel E. P.

2013-01-01

Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province. PMID:24358117

Spatially resolved sampling reveals dynamic microbial communities in rising hydrothermal plumes across a back-arc basin.

PubMed

Sheik, Cody S; Anantharaman, Karthik; Breier, John A; Sylvan, Jason B; Edwards, Katrina J; Dick, Gregory J

2015-06-01

Within hydrothermal plumes, chemosynthetic processes and microbe-mineral interactions drive primary productivity in deep-ocean food webs and may influence transport of elements such as iron. However, the source of microorganisms in plumes and the factors governing how these communities assemble are poorly understood, in part due to lack of data from early stages of plume formation. In this study, we examined microbial community composition of rising hydrothermal plumes from five vent fields along the Eastern Lau Spreading Center. Seafloor and plume microbial communities were significantly dissimilar and shared few phylotypes. Plume communities were highly similar to each other with significant differences in community membership only between Kilo Moana and Mariner, two vents that are separated by extremes in depth, latitude and geochemistry. Systematic sampling of waters surrounding the vents revealed that species richness and phylogenetic diversity was typically highest near the vent orifice, implying mixing of microbial communities from the surrounding habitats. Above-plume background communities were primarily dominated by SAR11, SAR324 and MG-I Archaea, while SUP05, Sulfurovum, Sulfurimonas, SAR324 and Alteromonas were abundant in plume and near-bottom background communities. These results show that the ubiquitous water-column microorganisms populate plume communities, and that the composition of background seawater exerts primary influence on plume community composition, with secondary influence from geochemical and/or physical properties of vents. Many of these pervasive deep-ocean organisms are capable of lithotrophy, suggesting that they are poised to use inorganic electron donors encountered in hydrothermal plumes.

Spatially resolved sampling reveals dynamic microbial communities in rising hydrothermal plumes across a back-arc basin

PubMed Central

Sheik, Cody S; Anantharaman, Karthik; Breier, John A; Sylvan, Jason B; Edwards, Katrina J; Dick, Gregory J

2015-01-01

Within hydrothermal plumes, chemosynthetic processes and microbe–mineral interactions drive primary productivity in deep-ocean food webs and may influence transport of elements such as iron. However, the source of microorganisms in plumes and the factors governing how these communities assemble are poorly understood, in part due to lack of data from early stages of plume formation. In this study, we examined microbial community composition of rising hydrothermal plumes from five vent fields along the Eastern Lau Spreading Center. Seafloor and plume microbial communities were significantly dissimilar and shared few phylotypes. Plume communities were highly similar to each other with significant differences in community membership only between Kilo Moana and Mariner, two vents that are separated by extremes in depth, latitude and geochemistry. Systematic sampling of waters surrounding the vents revealed that species richness and phylogenetic diversity was typically highest near the vent orifice, implying mixing of microbial communities from the surrounding habitats. Above-plume background communities were primarily dominated by SAR11, SAR324 and MG-I Archaea, while SUP05, Sulfurovum, Sulfurimonas, SAR324 and Alteromonas were abundant in plume and near-bottom background communities. These results show that the ubiquitous water-column microorganisms populate plume communities, and that the composition of background seawater exerts primary influence on plume community composition, with secondary influence from geochemical and/or physical properties of vents. Many of these pervasive deep-ocean organisms are capable of lithotrophy, suggesting that they are poised to use inorganic electron donors encountered in hydrothermal plumes. PMID:25489728

Dispersion of deep-sea hydrothermal vent effluents and larvae by submesoscale and tidal currents

NASA Astrophysics Data System (ADS)

Vic, Clément; Gula, Jonathan; Roullet, Guillaume; Pradillon, Florence

2018-03-01

Deep-sea hydrothermal vents provide sources of geochemical materials that impact the global ocean heat and chemical budgets, and support complex biological communities. Vent effluents and larvae are dispersed and transported long distances by deep ocean currents, but these currents are largely undersampled and little is known about their variability. Submesoscale (0.1-10 km) currents are known to play an important role for the dispersion of biogeochemical materials in the ocean surface layer, but their impact for the dispersion in the deep ocean is unknown. Here, we use a series of nested regional oceanic numerical simulations with increasing resolution (from δx = 6 km to δx = 0.75 km) to investigate the structure and variability of highly-resolved deep currents over the Mid-Atlantic Ridge (MAR) and their role on the dispersion of the Lucky Strike hydrothermal vent effluents and larvae. We shed light on a submesoscale regime of oceanic turbulence over the MAR at 1500 m depth, contrasting with open-ocean - i.e., far from topographic features - regimes of turbulence, dominated by mesoscales. Impacts of submesoscale and tidal currents on larval dispersion and connectivity among vent populations are investigated by releasing neutrally buoyant Lagrangian particles at the Lucky Strike hydrothermal vent. Although the absolute dispersion is overall not sensitive to the model resolution, submesoscale currents are found to significantly increase both the horizontal and vertical relative dispersion of particles at O(1-10) km and O(1-10) days, resulting in an increased mixing of the cloud of particles. A fraction of particles are trapped in submesoscale coherent vortices, which enable transport over long time and distances. Tidal currents and internal tides do not significantly impact the horizontal relative dispersion. However, they roughly double the vertical dispersion. Specifically, particles undergo strong tidally-induced mixing close to rough topographic features, which allows them to rise up in the water column and to cross topographic obstacles. The mesoscale variability controls at first order the connectivity between hydrothermal sites and we do not have long enough simulations to conclude on the connectivity between the different MAR hydrothermal sites. However, our simulations suggest that the connectivity might be increased by submesoscale and tidal currents, which act to spread the cloud of particles and help them cross topographic barriers.

Exploration and discovery in Yellowstone Lake: Results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

USGS Publications Warehouse

Morgan, L.A.; Shanks, Wayne C.; Lovalvo, D.A.; Johnson, S.Y.; Stephenson, W.J.; Pierce, K.L.; Harlan, S.S.; Finn, C.A.; Lee, G.; Webring, M.; Schulze, B.; Duhn, J.; Sweeney, R.; Balistrieri, L.

2003-01-01

Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (???1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem. Published by Elsevier Science B.V.

Diversity and characterization of bacteria associated with the deep-sea hydrothermal vent crab Austinograea sp. comparing with those of two shallow-water crabs by 16S ribosomal DNA analysis

PubMed Central

Wang, Minxiao; Liu, Yuan; Hui, Min

2017-01-01

For deep-sea hydrothermal vent crabs, recent investigations have revealed some epibiotic bacteria, but no study has described the bacterial community associated with the gill and intestine. In this study, the microbiota attached to the gill and intestine of the hydrothermal vent crab Austinograea sp. and two shallow-water crab species (Eriocheir sinensis and Portunus trituberculatus) were compared by high-throughput sequencing of 16S rDNA genes. The highest and lowest diversity in bacterial communities were observed in the gill and intestine of Austinograea sp., respectively. Non-metric multidimensional scaling (NMDS) analysis indicated that Austinograea sp. harbored a distinct microbial community. Operational taxonomic units (OTUs) for phylum Fusobacteria, class Epsilonproteobacteria, and genera Leucothrix, Polaribacter, Fusibacter, etc. were dominant in Austinograea sp. Of these, Leucothrix, Sulfurospirillum, and Arcobacter may be involved in oxidizing reduced sulfur compounds and sulfur metabolism; Marinomonas, Polaribacter adapted to the low temperature, and Fusibacter and Psychrilyobacter may survive well under hypoxic conditions. Bacteria commonly present in seawater were dominant in the gill, whereas anaerobic bacteria showed strikingly high abundance in the intestine. Interestingly, Firmicutes and Epsilonproteobacteria may complement each other in Austinograea sp., forming an internal environment. The diversified microbial community of Austinograea sp. reveals adaptation to the hydrothermal vent environment. PMID:29121118

Lessons from Suiyo Seamount studies, for understanding extreme (ancient?) microbial ecosystems in the deep-sea hydrothermal fields

NASA Astrophysics Data System (ADS)

Maruyama, A.; Higashi, Y.; Sunamura, M.; Urabe, T.

2004-12-01

Deep-sea hydrothermal ecosystems are driven with various geo-thermally modified, mainly reduced, compounds delivered from extremely hot subsurface environments. To date, several unique microbes including thermophilic archaeons have been isolated from/around vent chimneys. However, there is little information about microbes in over-vent and sub-vent fields. Here, we report several new findings on microbial diversity and ecology of the Suiyo Seamount that locates on the Izu-Bonin Arc in the northwest Pacific Ocean, as a result of the Japanese Archaean Park project, with special concern to the sub-vent biosphere. At first, we succeeded to reveal a very unique microbial ecosystem in hydrothermal plume reserved within the outer rim of the seamount crater, that is, it consisted of almost all metabolically active microbes belonged to only two Bacteria phylotypes, probably of sulfur oxidizers. In the center of the caldera seafloor (ca. 1,388-m deep) consisted mainly of whitish sands and pumices, we found many small chimneys (ca. 5-10 cm) and bivalve colonies distributed looking like gray to black patches. These geo/ecological features of the seafloor were supposed to be from a complex mixing of hydrothermal venting and strong water current near the seafloor. Through quantitative FISH analysis for various environmental samples, one of the two representative groups in the plume was assessed to be from some of the bivalve colonies. Using the Benthic Multi-coring System (BMS), total 10 points were drilled and 6 boreholes were maintained with stainless or titanium casing pipes. In the following submersible surveys, newly developed catheter- and column-type in situ growth chambers were deployed in and on the boreholes, respectively, for collecting indigenous sub-vent microbes. Finally, we succeeded to detect several new phylotypes of microbes in these chamber samples, e.g., within epsilon-Proteobacteria, a photosynthetic group of alpha-Proteobacteria, and hyperthermophile-related Euryarchaea. By the FISH analysis, however, some specific members of Bacteria that differed from those in the chamber samples were occasionally abundant in hot vent fluids. In clone library analysis of column-type chamber samples, we also found very unique vertical profiles in the community of Archaea, i.e., rich in uncultivable Marine Group I & II members in the upper and middle columns situated at a warm vent site, while heterotrophic thermophiles in the middle and bottom. In a bottom column sample from a hot vent site, hyperthermophilic anaerobes were detected. From these results, we will propose a vertical profile model for the sub-vent Archaea community. From geophysical, geochemical and geological surveys, this sub-vent ecosystem is supposed to be restricted in a shallow subsurface region. Whether these unique ecosystems are general in hydrothermal fields over the sea or specific only to this submarine volcano will be discussed.

Mapping the Spatial Distribution of CO2 release from Kīlauea Volcano, Hawaii, USA

NASA Astrophysics Data System (ADS)

Elias, T.; Werner, C. A.; Kern, C.; Sutton, A. J.; Hauri, E. H.; Kelly, P. J.

2014-12-01

Kīlauea Volcano is a large emitter of volcanic CO2 with emission rates ranging from 7500-30,000 t/d. However, Kīlauea presents a challenging situation for CO2 emission rate measurement in that the main source of SO2 is the active vent in Halema'uma'u Crater, whereas CO2 emits mainly from a large (> 1km2) diffuse region east of the vent. Previous researchers recognized this issue and advocated for the use of a plume-integrated concentration ratio paired with the SO2 emission to determine CO2 emission rates; however, this worked best prior to the opening of the summit vent in 2008, or when SO2emission was still diffuse as opposed to focused degassing from the vent. We used two techniques to study the spatial distribution and temporal variability of CO2 release from the summit caldera in July, 2014. Eddy covariance measurements made at 14 locations in the area of diffuse emission resulted in elevated fluxes that generally ranged from 500 to > 5000 g/m2d, or typical of other volcanic and hydrothermal areas worldwide. MultiGas measurements of the CO2 and SO2 concentration in air at 1-m above the ground identified approximately seven areas of elevated area of CO2 degassing in the caldera. The CO2 concentrations in air were spatially well correlated to approximately 100 m and displayed anisotropy that was consistent with the measured wind direction. Areas of highest CO2 concentration correlated with the areas of highest flux using the eddy covariance method and were found near the middle of the caldera approximately 1 km NE of the active vent. This area overlies the inferred location of the shallow summit reservoir, and is characterized by linear fractures with adhered sublimate deposits at the surface. A few of the fractures are visibly fuming, but much of the degassing in the area is not apparent. Future work includes monitoring the fluxes in this area over time, and attempting to quantify emission rates from the areas of measured flux.

Can Life Begin on Enceladus? A Perspective from Hydrothermal Chemistry

PubMed Central

Damer, Bruce

2017-01-01

Abstract Enceladus is a target of future missions designed to search for existing life or its precursors. Recent flybys of Enceladus by the Cassini probe have confirmed the existence of a long-lived global ocean laced with organic compounds and biologically available nitrogen. This immediately suggests the possibility that life could have begun and may still exist on Enceladus. Here we will compare the properties of two proposed sites for the origin of life on Earth—hydrothermal vents on the ocean floor and hydrothermal volcanic fields at the surface—and ask whether similar conditions could have fostered the origin of life on Enceladus. The answer depends on which of the two sites would be more conducive for the chemical evolution leading to life's origin. A hydrothermal vent origin would allow life to begin in the Enceladus ocean, but if the origin of life requires freshwater hydrothermal pools undergoing wet-dry cycles, the Enceladus ocean could be habitable but lifeless. These arguments also apply directly to Europa and indirectly to early Mars. Key Words: Enceladus—Hydrothermal vents—Hydrothermal fields—Origin of life. Astrobiology 17, 834–839. PMID:28682665

Simulating a Submarine Hydrothermal Vent

NASA Image and Video Library

2013-01-16

A team of scientists at NASA Jet Propulsion Laboratory is testing whether organic molecules can be brewed in a simulated ocean vent. Pictured here is Lauren White, a member of the NASA Astrobiology Icy Worlds team.

Tracking Spatial and Temporal Changes in Microbial Metabolic Potential and Gene Expression Patterns Across Geochemical Gradients at Axial Seamount

NASA Astrophysics Data System (ADS)

Fortunato, C. S.; Butterfield, D. A.; Larson, B.; Algar, C. K.; Huber, J. A.

2016-12-01

Microbial communities living both near and within the subseafloor are important players in the biogeochemical cycling of the deep ocean. To better understand the metabolic and gene expression patterns of these understudied communities, we collected low-temperature diffuse fluids for metagenomic, metatranscriptomic, and geochemical analyses from Axial Seamount, an active submarine volcano off the coast of Oregon, USA in 2013-2015. In April of 2015 Axial Seamount erupted along its north rift, five months before the 2015 samples were collected. This study thus provides both spatial and temporal analysis of subseafloor microbial communities pre and post eruption. The time series for this study focused on three vents at the south end of the caldera: Anemone, Marker 33, and Marker 113. Chemistry data shows that at each vent there are different geochemical conditions and thus a potentially different microbial metabolic profile. Anemone has the most oxidizing conditions and the highest abundance and expression of sulfur oxidation genes, attributed to both SUP05 and Epsilonproteobacteria. The most reducing conditions were observed at Marker 113, the site with the lowest oxygen concentration and where methanogenesis was the dominant metabolism, with 18.5% of all annotated transcripts attributed to methanogenesis. Although individual vents were metabolically distinct, there was very little variation in the overall taxonomic and metabolic profiles of each vent across years, even after the 2015 eruption. A diffuse fluid sample taken from the North Rift Zone post eruption showed similar community taxonomy to both Anemone and Marker 33; analyses of the metabolic potential and gene expression at this site is ongoing and will act as a comparison between the communities of the time series vents and those that were closer to the eruption site. Together, these chemical and `omic datasets reveal a dynamic microbial community at each vent, taxonomically diverse and involved in a wide array of biogeochemical transformations. Results are being used to model the functional dynamics and fluxes of vent communities to more closely link microbiological productivity at hydrothermal systems to deep-sea biogeochemical processes and will be also used to inform future projects using instrumentation on the cabled array at Axial Seamount.

Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan

PubMed Central

Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

2016-01-01

Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments. PMID:26849440

Some features of the trace metal biogeochemistry in the deep-sea hydrothermal vent fields (Menez Gwen, Rainbow, Broken Spur at the MAR and 9°50‧N at the EPR): A synthesis

NASA Astrophysics Data System (ADS)

Demina, Ludmila L.; Holm, Nils G.; Galkin, Sergey V.; Lein, Alla Yu.

2013-10-01

Along with summarizing the published literature and our own data some new results on properties of the trace metal biogeochemistry in the deep-sea hydrothermal ecosystems at the Mid-Atlantic Ridge (MAR) and East Pacific Rise (EPR) are shown. Differences in mean concentrations of big group of trace metals (Fe, Mn, Zn, Cu, Ni, Cr, Co, As, Pb, Cd, Ag, Hg) between the biotope water of the low- and high-temperature hydrothermal vent fields were firstly revealed. The same trace metals were studied in different groups of organisms within different temperature zones at one and the same vent field (9°50‧N EPR), as well as in fauna inhabiting geochemically different vent sites. Distribution patterns of Fe, Mn, Zn, Cu, Cd, Pb, Ag, Ni, Cr, Co, As, Se, Sb, and Hg in different taxa gave an evidence of the influence of environmental and biological parameters on their bioaccumulation in organisms. Among the animals a particular “champion” with respect to the trace metal content was found to be a polychaeta Alvinella pompejana that inhabits the hottest places of the vent sulfide chimneys of the 9°50‧N field, EPR. New data on the trace metal distribution between soft tissues and carbonate shell let us estimate a role of biomineralization in the accumulation of metals in the Bathimodiolus mussels. Contrasting geochemical behavior was revealed for Cu that is enriched in soft tissues of mussels and depleted in shells, on the one hand, and Mn that is accumulated almost totally in mussel shells, on the other hand. Deep-sea hydrothermal biological communities demonstrate a strong concentration function, and bioconcentration factors (BCF) of trace metals estimated for Bathimodiolus mussels collected at the four hydrothermal fields vary within the limits of n102-n105 and are similar to that of the littoral mussels. Due to this and to the high values of biomasses per square meter, the hydrothermal fauna may be considered as a newly discovered biological filter of the oceans.

Monitoring Endeavour vent field deep-sea ecosystem dynamics through NEPTUNE Canada seafloor observatory

NASA Astrophysics Data System (ADS)

Matabos, M.; NC Endeavour Science Team

2010-12-01

Mid-ocean ridges are dynamic systems where the complex linkages between geological, biological, chemical, and physical processes are not yet well understood. Indeed, the poor accessibility to the marine environment has greatly limited our understanding of deep-sea ecosystems. Undersea cabled observatories offer the power and bandwidth required to conduct long-term and high-resolution time-series observations of the seafloor. Investigations of mid-ocean ridge hydrothermal ecosystem require interdisciplinary studies to better understand the dynamics of vent communities and the physico-chemical forces that influence them. NEPTUNE Canada (NC) regional observatory is located in the Northeast Pacific, off Vancouver Island (BC, Canada), and spans ecological environments from the beach to the abyss. In September-October 2010, NC will be instrumenting its 5th node, including deployment of a multi-disciplinary suite of instruments in two vent fields on the Endeavour Segment of the Juan de Fuca Ridge. These include a digital camera, an imaging sonar for vent plumes and flow characteristics (i.e. COVIS), temperature resistivity probes, a water sampler and seismometers. In 2011, the TEMPO-mini, a new custom-designed camera and sensor package created by IFREMER for real-time monitoring of hydrothermal faunal assemblages and their ecosystems (Sarrazin et al. 2007), and a microbial incubator, will added to the network in the Main Endeavour and Mothra vent fields. This multidisciplinary approach will involve a scientific community from different institutions and countries. Significant experience aids in this installation. For example, video systems connected to VENUS and NC have led to the development of new experimental protocols for time-series observations using seafloor cameras, including sampling design, camera calibration and image analysis methodologies (see communication by Aron et al. and Robert et al.). Similarly, autonomous deployment of many of the planned instruments has informed their adoption to the cabled instrument array at the Endeavour hydrothermal vents. This provides a unique laboratory for researchers to conduct long-term, integrated studies of hydrothermal vent ecosystem dynamics in relation to environmental variability at different temporal scales. In addition to programmed time-series monitoring, the NC infrastructure will also permit manual and automated modification of observational protocols in response to natural events. This will enhance our ability to document how the entire ecosystem reacts to potentially critical but short-lived environmental forces (e.g. seismic events). Sarrazin et al 2007. TEMPO: a new ecological module for studying deep-sea community dynamics at hydrothermal vents. OCEANS’07 IEEE Aberdeen Conference Proceedings

Chicxulub: testing for post-impact hydrothermal inputs into the Tertiary ocean

NASA Astrophysics Data System (ADS)

Rowe, A.; Wilkinson, J.; Morgan, J.

2003-04-01

Large terrestrial impacts produce intense fracturing of the crust and large melt sheets, providing ideal conditions for extensive hydrothermal circulation. In marine settings, such as Chicxulub, there is the potential for downward penetration of cold seawater, heating by the thermal anomaly at the impact site and leaching of metals, prior to buoyancy driven flow back to the surface. There, fluids may undergo venting into the water column. A large proportion of the metals in such vent fluids precipitate close to the site of discharge; however, a proportion of the fluid is dispersed as a hydrothermal plume. Dissolved and particulate materials (in particular manganese and iron oxyhydroxides) can be carried for several hundreds of kilometers, before falling out to form metal-rich sediments. A series of Tertiary core samples has been obtained from the International Continental Drilling Program at Chicxulub (CSDP). These comprise fine-grained cream coloured carbonate sediments with fine laminations. Transmitted light and cathodoluminescence petrography have been used to carry out a preliminary characterization of the samples. Multi-element analysis has also been undertaken by ICP-AES. Samples were reduced to powder and digested using a nitric-perchloric-hydrofluoric acid attack. Rare earth elements (REE) have been analysed by ICP-MS and solutions were prepared using a modified nitric-perchloric-hydrofluoric acid attack. Geochemical analyses have been carried out to test for characteristic signals of hydrothermal input, such as enrichments in Mn, Fe, Cu, Zn, Pb, Mg, Ba, Co, Cr and Ni. The REE are scavenged from seawater onto iron oxide surfaces in the plume; hence anomalous REE concentrations are also indicative of hydrothermal addition. Furthermore, the type of anomaly can differentiate between sediments proximal (+ve Eu) distal (-ve Ce) to the vent site. The stratigraphic extent of any anomalies can be used to constrain the duration of any post-impact circulation. The wider significance of such hydrothermal circulation, if identified, include the potential formation of hydrothermal mineralization and vent-related ecosystems in the Chicxulub crater. The results will also have implications for the exploration of impact-related hydrothermal ecosystems on other planets.

Anhydrite precipitation in seafloor hydrothermal systems

NASA Astrophysics Data System (ADS)

Theissen-Krah, Sonja; Rüpke, Lars H.

2016-04-01

The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists. Heinrich, C. A., and P. A. Candela (2014), 13.1 - Fluids and Ore Formation in the Earth's Crust, in Treatise on Geochemistry (Second Edition), edited by H. D. Holland and K. K. Turekian, pp. 1-28, Elsevier, Oxford. Jupp, T., and A. Schultz (2000), A thermodynamic explanation for black smoker temperatures, Nature, 403(6772), 880-883.

Vailulu'u Seamount, Samoa: Life and Death at the Edge of An Active Submarine Volcano

NASA Astrophysics Data System (ADS)

Vailulu'U Research Group, T.

2005-12-01

Exploration of Vailulu'u seamount (14°13'S; 169°04'W) by manned submersible, ROV, and surface ship revealed a new, 300m tall volcano that has grown in the summit crater in less than four years. This shows that Vailulu'u's eruption behavior is at this stage not predictable and continued growth could allow Vailulu'u to breach sea level within decades Several types of hydrothermal vents fill Vailulu'u crater with particulates that reduce visibility to less than a few meters in some regions. Hydrothermal solutions mix with seawater that enters the crater from its breaches to produce distinct biological habitats. Low temperature hydrothermal vents can produce Fe-oxide chimneys or up to one meter-thick microbial mats. Higher temperature vents (85°C) produce low salinity acidic fluids containing buoyant droplets of immiscible CO2. Low temperature hydrothermal vents at Nafanua summit (708m depth) support a thriving population of eels (Dysommia rusosa). The areas around the high temperature vents and the moat and remaining crater around the new volcano is almost devoid of any macroscopic life and is littered with fish, and mollusk carcasses that apparently died from exposure to hydrothermal fluid components in deeper crater waters. Acid- tolerant polychaetes adapt to this environment and feed near and on these carcasses. Vailulu'u presents a natural laboratory for the study of how seamounts and their volcanic systems interact with the hydrosphere to produce distinct biological habitats, and how marine life can adapt to these conditions or be trapped in a toxic volcanic system that leads to mass mortality. The Vailulu'u research team: Hubert Staudigel, Samantha Allen, Brad Bailey, Ed Baker, Sandra Brooke, Ryan Delaney, Blake English, Lisa Haucke, Stan Hart, John Helly, Ian Hudson, Matt Jackson, Daniel Jones, Alison Koleszar, Anthony Koppers, Jasper Konter, Laurent Montesi, Adele Pile, Ray Lee, Scott Mcbride, Julie Rumrill, Daniel Staudigel, Brad Tebo, Alexis Templeton, Rhea Workman, Craig Young, Robert Zierenberg.

Looking for Larvae Above an Erupting Submarine Volcano, NW Rota-1, Mariana Arc

NASA Astrophysics Data System (ADS)

Hanson, M.; Beaulieu, S.; Tunnicliffe, V.; Chadwick, W.; Breuer, E. R.

2015-12-01

In 2009 the first marine protected areas for deep-sea hydrothermal vents in U.S. waters were established as part of the Volcanic Unit of the Marianas Trench Marine National Monument. In this region, hydrothermal vents are located along the Mariana Arc and back-arc spreading center. In particular hydrothermal vents are located near the summit of NW Rota-1, an active submarine volcano on the Mariana Arc which was erupting between 2003 through 2010 and ceased as of 2014. In late 2009, NW Rota-1 experienced a massive landslide decimating the habitat on the southern side of the volcano. This presented an enormous natural disturbance to the community. This project looked at zooplankton tow samples taken from the water column above NW Rota-1 in 2010, searching specifically for larvae which have the potential to recolonize the sea floor after such a major disturbance. We focused on samples for which profiles with a MAPR sensor indicated hydrothermal plumes in the water column. Samples were sorted in entirety into coarse taxa, and then larvae were removed for DNA barcoding. Overall zooplankton composition was dominated by copepods, ostracods, and chaetognaths, the majority of which are pelagic organisms. Comparatively few larvae of benthic invertebrates were found, but shrimp, gastropod, barnacle, and polychaete larvae did appear in low numbers in the samples. Species-level identification obtained via genetic barcoding will allow for these larvae to be matched to species known to inhabit the benthic communities at NW Rota-1. Identified larvae will give insight into the organisms which can re-colonize the seafloor vent communities after a disturbance such as the 2009 landslide. Communities at hydrothermal vents at other submarine volcanoes in the Monument also can act as sources for these planktonic, recolonizing larvae. As the microinvertebrate biodiversity in the Monument has yet to be fully characterized, our project also provides an opportunity to better describe both the zooplankton and benthic community composition in this area of the Monument.

Geochemically induced shifts in catabolic energy yields explain past ecological changes of diffuse vents in the East Pacific Rise 9°50'N area

PubMed Central

2012-01-01

The East Pacific Rise (EPR) at 9°50'N hosts a hydrothermal vent field (Bio9) where the change in fluid chemistry is believed to have caused the demise of a tubeworm colony. We test this hypothesis and expand on it by providing a thermodynamic perspective in calculating free energies for a range of catabolic reactions from published compositional data. The energy calculations show that there was excess H2S in the fluids and that oxygen was the limiting reactant from 1991 to 1997. Energy levels are generally high, although they declined in that time span. In 1997, sulfide availability decreased substantially and H2S was the limiting reactant. Energy availability dropped by a factor of 10 to 20 from what it had been between 1991 and 1995. The perishing of the tubeworm colonies began in 1995 and coincided with the timing of energy decrease for sulfide oxidizers. In the same time interval, energy availability for iron oxidizers increased by a factor of 6 to 8, and, in 1997, there was 25 times more energy per transferred electron in iron oxidation than in sulfide oxidation. This change coincides with a massive spread of red staining (putative colonization by Fe-oxidizing bacteria) between 1995 and 1997. For a different cluster of vents from the EPR 9°50'N area (Tube Worm Pillar), thermodynamic modeling is used to examine changes in subseafloor catabolic metabolism between 1992 and 2000. These reactions are deduced from deviations in diffuse fluid compositions from conservative behavior of redox-sensitive species. We show that hydrogen is significantly reduced relative to values expected from conservative mixing. While H2 concentrations of the hydrothermal endmember fluids were constant between 1992 and 1995, the affinities for hydrogenotrophic reactions in the diffuse fluids decreased by a factor of 15 and then remained constant between 1995 and 2000. Previously, these fluids have been shown to support subseafloor methanogenesis. Our calculation results corroborate these findings and indicate that the 1992-1995 period was one of active growth of hydrogenotrophic communities, while the system was more or less at steady state between 1995 and 2000. PMID:22283983

Adaptations to Hydrothermal Vent Life in Kiwa tyleri, a New Species of Yeti Crab from the East Scotia Ridge, Antarctica.

PubMed

Thatje, Sven; Marsh, Leigh; Roterman, Christopher Nicolai; Mavrogordato, Mark N; Linse, Katrin

2015-01-01

Hydrothermal vents in the Southern Ocean are the physiologically most isolated chemosynthetic environments known. Here, we describe Kiwa tyleri sp. nov., the first species of yeti crab known from the Southern Ocean. Kiwa tyleri belongs to the family Kiwaidae and is the visually dominant macrofauna of two known vent sites situated on the northern and southern segments of the East Scotia Ridge (ESR). The species is known to depend on primary productivity by chemosynthetic bacteria and resides at the warm-eurythermal vent environment for most of its life; its short-range distribution away from vents (few metres) is physiologically constrained by the stable, cold waters of the surrounding Southern Ocean. Kiwa tylerihas been shown to present differential life history adaptations in response to this contrasting thermal environment. Morphological adaptations specific to life in warm-eurythermal waters, as found on - or in close proximity of - vent chimneys, are discussed in comparison with adaptations seen in the other two known members of the family (K. hirsuta, K. puravida), which show a preference for low temperature chemosynthetic environments.

Biogeography of bacteriophages at four hydrothermal vent sites in the Antarctic based on g23 sequence diversity.

PubMed

Millard, Andrew D; Pearce, David; Zwirglmaier, Katrin

2016-04-01

In this study, which was carried out within the ChEsSO consortium project (Chemosynthetically driven ecosystems south of the Polar Front), we sampled two hydrothermal vent sites on the East Scotia Ridge, Scotia Sea, one in the Kemp Caldera, South Sandwich Arc and one in the Bransfield Strait, north-west of the Antarctic Peninsula, which exhibit strong differences in their chemical characteristics. We compared a subset of their bacteriophage population by Sanger- and 454-sequencing of g23, which codes for the major capsid protein of T4likeviruses. We found that the sites differ vastly in their bacteriophage diversity, which reflects the differences in the chemical conditions and therefore putatively the differences in microbial hosts living at these sites. Comparing phage diversity in the vent samples to other aquatic samples, the vent samples formed a distinct separate cluster, which also included the non-vent control samples that were taken several hundred meters above the vent chimneys. This indicates that the influence of the vents on the microbial population and therefore also the bacteriophage population extends much further than anticipated. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hydrothermal Plume Activity at Teahitia Seamount: Re-Awakening of the Society Islands Hot-Spot?

NASA Astrophysics Data System (ADS)

German, C. R.; Xu, G.; Yeo, I. A.; Walker, S. L.; Moffett, J.; Cutter, G. A.; Devey, C. W.; Hyvernaud, O.; Reymond, D.; Resing, J. A.

2016-12-01

We report results from a combined mapping and CTD-rosette investigation of the summit of Teahitia Seamount, Society Islands hot-spot, that indicates that high temperature venting may have been present by late 2013 at a site that only hosted low-temperature vents ( 30°C) when previously visited by submersible, 25 years earlier. In 2013, a non-buoyant hydrothermal plume containing high concentrations (>100nmol/L) of both dissolved and total dissolvable Fe was observed at an apparent rise-height of 110-140m above a seafloor source at 1500-1530m water depth, implying a heat-flux for the underlying venting of 13-35MW. From a comparison to the past evolution of venting at Loihi seamount (Hawaii), coupled with an examination of recent seismicity detected by the Polynesian Seismic Network, we hypothesize that venting at Teahitia may have undergone perturbation only recently and that this, in turn, may be linked to a re-awakening of the Society Islands hotspot.

Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents

NASA Technical Reports Server (NTRS)

Conrad, P. G.; Lane, A. L.; Bhartia, R.; Hug, W. H.

2004-01-01

We have developed a non-contact, optical life detection instrument that can detect organic chemical biosignatures in a number of different environments, including dry land, shallow aqueous, deep marine or in ice. Hence, the instrument is appropriate as a biosignature survey tool both for Mars exploration or in situ experiments in an ice-covered ocean such as one might wish to explore on Europa. Here, we report the results we obtained on an expedition aboard the Russian oceanographic vessel Akademik Mstislav Keldysh to hydrothermal vent sites in the Pacific Ocean using our life detection instrument MCDUVE, a multichannel, deep ultraviolet excitation fluorescence detector. MCDUVE detected organic material distribution on rocks near the vent, as well as direct detection of organisms, both microbial and microscopic. We also were able to detect organic material issuing directly from vent chimneys, measure the organic signature of the water column as we ascended, and passively observe the emission of light directly from some vents.

Distribution and relative importance of jellyfish in a region of hydrothermal venting

NASA Astrophysics Data System (ADS)

Burd, Brenda J.; Thomson, Richard E.

2000-09-01

Net sampling to 3000 m depth at Endeavour Ridge in the northeast Pacific in July 1991-1994 shows that medusae in the immediate vicinity of the hydrothermal vent fields often make up a larger proportion of the total zooplankton abundance and biomass from mesopelagic to bathypelagic depths than in the surrounding waters. This was particularly evident in the dominant Trachymedusae, and least evident in the siphonophores. In addition, the large red Scyphomedusa Stygiomedusa gigantea was a major biomass component in the region of the deep (1000-1800 m depth) migrating scattering layers at the vent field, but was not found in any net tows greater than 10 km away from vents. There is no concurrent increase in relative or percent biomass of fish or chaetognaths, which are the other major predators in the community. We hypothesize that predaceous medusae respond opportunistically to the enhanced zooplankton biomass throughout the water column around vents in spring to early summer, in a way that other predators do not.

Identification of 16S Ribosomal DNA-Defined Bacterial Populations at a Shallow Submarine Hydrothermal Vent near Milos Island (Greece)

PubMed Central

Sievert, Stefan M.; Kuever, Jan; Muyzer, Gerard

2000-01-01

In a recent publication (S. M. Sievert, T. Brinkhoff, G. Muyzer, W. Ziebis, and J. Kuever, Appl. Environ. Microbiol. 65:3834–3842, 1999) we described spatiotemporal changes in the bacterial community structure at a shallow-water hydrothermal vent in the Aegean Sea near the isle of Milos (Greece). Here we describe identification and phylogenetic analysis of the predominant bacterial populations at the vent site and their distribution at the vent site as determined by sequencing of DNA molecules (bands) excised from denaturing gradient gels. A total of 36 bands could be sequenced, and there were representatives of eight major lineages of the domain Bacteria. Cytophaga-Flavobacterium and Acidobacterium were the most frequently retrieved bacterial groups. Less than 33% of the sequences exhibited 90% or more identity with cultivated organisms. The predominance of putative heterotrophic populations in the sequences retrieved is explained by the input of allochthonous organic matter at the vent site. PMID:10877814

Spatial and Temporal Population Genetics at Deep-Sea Hydrothermal Vents Along the East Pacific Rise and Galapagos Rift

DTIC Science & Technology

2008-09-01

locality and moment in time. The present composition of alleles within a population establishes its future course of persistence or extinction, adaptation ...Calyptogena magnified NEPR, GAR 3,340 17,n,c 0.016 No5’’ nonplanktotrophic"’ short Gastropods Eulepetop.si.s vilrea NEPR, GAR 3,340 10 0.059 No...Massachusetts Institute of Technology/Woods Hole Oceanographic Institution, MA. Adams DK, Mullineaux LS (2008) Supply of gastropod larvae to hydrothermal vents

Deepest and hottest hydrothermal activity in the Okinawa Trough: the Yokosuka site at Yaeyama Knoll

PubMed Central

Miyazaki, Junichi; Kawagucci, Shinsuke; Makabe, Akiko; Takahashi, Ayu; Kitada, Kazuya; Torimoto, Junji; Matsui, Yohei; Tasumi, Eiji; Shibuya, Takazo; Nakamura, Kentaro; Horai, Shunsuke; Sato, Shun; Ishibashi, Jun-ichiro; Kanzaki, Hayato; Nakagawa, Satoshi; Hirai, Miho; Takaki, Yoshihiro; Okino, Kyoko; Watanabe, Hiromi Kayama; Kumagai, Hidenori

2017-01-01

Since the initial discovery of hydrothermal vents in 1977, these ‘extreme’ chemosynthetic systems have been a focus of interdisciplinary research. The Okinawa Trough (OT), located in the semi-enclosed East China Sea between the Eurasian continent and the Ryukyu arc, hosts more than 20 known vent sites but all within a relatively narrow depth range (600–1880 m). Depth is a significant factor in determining fluid temperature and chemistry, as well as biological composition. However, due to the narrow depth range of known sites, the actual influence of depth here has been poorly resolved. Here, the Yokosuka site (2190 m), the first OT vent exceeding 2000 m depth is reported. A highly active hydrothermal vent site centred around four active vent chimneys reaching 364°C in temperature, it is the hottest in the OT. Notable Cl depletion (130 mM) and both high H2 and CH4 concentrations (approx. 10 mM) probably result from subcritical phase separation and thermal decomposition of sedimentary organic matter. Microbiota and fauna were generally similar to other sites in the OT, although with some different characteristics. In terms of microbiota, the H2-rich vent fluids in Neuschwanstein chimney resulted in the dominance of hydrogenotrophic chemolithoautotrophs such as Thioreductor and Desulfobacterium. For fauna, the dominance of the deep-sea mussel Bathymodiolus aduloides is surprising given other nearby vent sites are usually dominated by B. platifrons and/or B. japonicus, and a sponge field in the periphery dominated by Poecilosclerida is unusual for OT vents. Our insights from the Yokosuka site implies that although the distribution of animal species may be linked to depth, the constraint is perhaps not water pressure and resulting chemical properties of the vent fluid but instead physical properties of the surrounding seawater. The potential significance of these preliminary results and prospect for future research on this unique site are discussed. PMID:29308272

Biogeography and Biodiversity in Sulfide Structures of Active and Inactive Vents at Deep-Sea Hydrothermal Fields of the Southern Mariana Trough▿ †

PubMed Central

Kato, Shingo; Takano, Yoshinori; Kakegawa, Takeshi; Oba, Hironori; Inoue, Kazuhiko; Kobayashi, Chiyori; Utsumi, Motoo; Marumo, Katsumi; Kobayashi, Kensei; Ito, Yuki; Ishibashi, Jun-ichiro; Yamagishi, Akihiko

2010-01-01

The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and microbial ecosystems in marine environments. PMID:20228114

Deepest and hottest hydrothermal activity in the Okinawa Trough: the Yokosuka site at Yaeyama Knoll

NASA Astrophysics Data System (ADS)

Miyazaki, Junichi; Kawagucci, Shinsuke; Makabe, Akiko; Takahashi, Ayu; Kitada, Kazuya; Torimoto, Junji; Matsui, Yohei; Tasumi, Eiji; Shibuya, Takazo; Nakamura, Kentaro; Horai, Shunsuke; Sato, Shun; Ishibashi, Jun-ichiro; Kanzaki, Hayato; Nakagawa, Satoshi; Hirai, Miho; Takaki, Yoshihiro; Okino, Kyoko; Watanabe, Hiromi Kayama; Kumagai, Hidenori; Chen, Chong

2017-12-01

Since the initial discovery of hydrothermal vents in 1977, these `extreme' chemosynthetic systems have been a focus of interdisciplinary research. The Okinawa Trough (OT), located in the semi-enclosed East China Sea between the Eurasian continent and the Ryukyu arc, hosts more than 20 known vent sites but all within a relatively narrow depth range (600-1880 m). Depth is a significant factor in determining fluid temperature and chemistry, as well as biological composition. However, due to the narrow depth range of known sites, the actual influence of depth here has been poorly resolved. Here, the Yokosuka site (2190 m), the first OT vent exceeding 2000 m depth is reported. A highly active hydrothermal vent site centred around four active vent chimneys reaching 364°C in temperature, it is the hottest in the OT. Notable Cl depletion (130 mM) and both high H2 and CH4 concentrations (approx. 10 mM) probably result from subcritical phase separation and thermal decomposition of sedimentary organic matter. Microbiota and fauna were generally similar to other sites in the OT, although with some different characteristics. In terms of microbiota, the H2-rich vent fluids in Neuschwanstein chimney resulted in the dominance of hydrogenotrophic chemolithoautotrophs such as Thioreductor and Desulfobacterium. For fauna, the dominance of the deep-sea mussel Bathymodiolus aduloides is surprising given other nearby vent sites are usually dominated by B. platifrons and/or B. japonicus, and a sponge field in the periphery dominated by Poecilosclerida is unusual for OT vents. Our insights from the Yokosuka site implies that although the distribution of animal species may be linked to depth, the constraint is perhaps not water pressure and resulting chemical properties of the vent fluid but instead physical properties of the surrounding seawater. The potential significance of these preliminary results and prospect for future research on this unique site are discussed.

Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean

PubMed Central

Mitarai, Satoshi; Watanabe, Hiromi; Nakajima, Yuichi; Shchepetkin, Alexander F.; McWilliams, James C.

2016-01-01

Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth. PMID:26929376

Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean.

PubMed

Mitarai, Satoshi; Watanabe, Hiromi; Nakajima, Yuichi; Shchepetkin, Alexander F; McWilliams, James C

2016-03-15

Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth.

From deep-sea volcanoes to human pathogens: a conserved quorum-sensing signal in Epsilonproteobacteria

PubMed Central

Pérez-Rodríguez, Ileana; Bolognini, Marie; Ricci, Jessica; Bini, Elisabetta; Vetriani, Costantino

2015-01-01

Chemosynthetic Epsilonproteobacteria from deep-sea hydrothermal vents colonize substrates exposed to steep thermal and redox gradients. In many bacteria, substrate attachment, biofilm formation, expression of virulence genes and host colonization are partly controlled via a cell density-dependent mechanism involving signal molecules, known as quorum sensing. Within the Epsilonproteobacteria, quorum sensing has been investigated only in human pathogens that use the luxS/autoinducer-2 (AI-2) mechanism to control the expression of some of these functions. In this study we showed that luxS is conserved in Epsilonproteobacteria and that pathogenic and mesophilic members of this class inherited this gene from a thermophilic ancestor. Furthermore, we provide evidence that the luxS gene is expressed—and a quorum-sensing signal is produced—during growth of Sulfurovum lithotrophicum and Caminibacter mediatlanticus, two Epsilonproteobacteria from deep-sea hydrothermal vents. Finally, we detected luxS transcripts in Epsilonproteobacteria-dominated biofilm communities collected from deep-sea hydrothermal vents. Taken together, our findings indicate that the epsiloproteobacterial lineage of the LuxS enzyme originated in high-temperature geothermal environments and that, in vent Epsilonproteobacteria, luxS expression is linked to the production of AI-2 signals, which are likely produced in situ at deep-sea vents. We conclude that the luxS gene is part of the ancestral epsilonproteobacterial genome and represents an evolutionary link that connects thermophiles to human pathogens. PMID:25397946

From deep-sea volcanoes to human pathogens: a conserved quorum-sensing signal in Epsilonproteobacteria.

PubMed

Pérez-Rodríguez, Ileana; Bolognini, Marie; Ricci, Jessica; Bini, Elisabetta; Vetriani, Costantino

2015-05-01

Chemosynthetic Epsilonproteobacteria from deep-sea hydrothermal vents colonize substrates exposed to steep thermal and redox gradients. In many bacteria, substrate attachment, biofilm formation, expression of virulence genes and host colonization are partly controlled via a cell density-dependent mechanism involving signal molecules, known as quorum sensing. Within the Epsilonproteobacteria, quorum sensing has been investigated only in human pathogens that use the luxS/autoinducer-2 (AI-2) mechanism to control the expression of some of these functions. In this study we showed that luxS is conserved in Epsilonproteobacteria and that pathogenic and mesophilic members of this class inherited this gene from a thermophilic ancestor. Furthermore, we provide evidence that the luxS gene is expressed--and a quorum-sensing signal is produced--during growth of Sulfurovum lithotrophicum and Caminibacter mediatlanticus, two Epsilonproteobacteria from deep-sea hydrothermal vents. Finally, we detected luxS transcripts in Epsilonproteobacteria-dominated biofilm communities collected from deep-sea hydrothermal vents. Taken together, our findings indicate that the epsiloproteobacterial lineage of the LuxS enzyme originated in high-temperature geothermal environments and that, in vent Epsilonproteobacteria, luxS expression is linked to the production of AI-2 signals, which are likely produced in situ at deep-sea vents. We conclude that the luxS gene is part of the ancestral epsilonproteobacterial genome and represents an evolutionary link that connects thermophiles to human pathogens.

A New Species of the Genus Kiwa (Decapoda: Anomura) from the Hydrothermal Vent of the Australia-Antarctic Ridge

NASA Astrophysics Data System (ADS)

Won, Y. J.; Lee, S. H.; Lee, W. K.

2014-12-01

Due to extreme weather conditions and remoteness to access, the great part of the Southern Ocean remains to be explored. Therefore, little is known about the Circum-Antarctic Ridge (CAR) system and its hydrothermal vent ecosystem underlying the Southern Ocean. We report the first discovery of a new deep-sea hydrothermal vent field and a new anomuran species from the Australia-Antarctic Ridge (AAR), the highest latitude (62°S; 158°E) explored in the Southern Ocean up to date. At this site, a new anomuran species which belongs to the genus Kiwa known as 'yeti crabs' was found. Morphologically, this species has characteristics of the genus Kiwa, including fifth pereopod inserted below sterna plastron, third sternite strongly produced anteriorly, and eyes extremely reduced. However, the new species differs from the other known species of Kiwa, K. hirsuta and K. puravida, showing relatively short rostrum and slender dactylus on second to fourth pereopods. Phylogenetic analysis using DNA sequences of eight genetic loci also supported the result of morphological analysis, confirming this species as a new Kiwa species, Kiwa n. sp. In addition, phylogenetic tree revealed the evolutionary relationship among the Kiwa species, presenting the Kiwa n. sp. as the sister species to K. puravida which inhabits the methane cold seep on the Pacific continental slope off Costa Rica. Considering the geography and the physicochemical environment, this unlikely result casts a mystery to be solved through further taxon sampling particularly from as-yet-unexplored vents and seeps. Discovery of the hydrothermal vent and Kiwa n. sp. from the AAR segment is significant because this site is located in the high latitude of the southern hemisphere and it is the region affected by the Antarctic Circumpolar Current (ACC). Future research on the relation of Kiwa n. sp. and the other Kiwa species affected by the ACC will provide an idea about the biogeography and the evolutionary connections of the vent faunas in the CAR system.

Rapid growth of mineral deposits at artificial seafloor hydrothermal vents

PubMed Central

Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken

2016-01-01

Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes vented hydrothermal fluids in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal vent more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal fluids with the ambient seawater. PMID:26911272

Gas Chemistry of Submarine Hydrothermal Venting at Maug Caldera, Mariana Arc

NASA Astrophysics Data System (ADS)

Embley, R. W.; Lupton, J. E.; Butterfield, D. A.; Lilley, M. D.; Evans, L. J.; Olson, E. J.; Resing, J. A.; Buck, N.; Larson, B. I.; Young, C.

2014-12-01

Maug volcano consists of 3 islands that define the perimeter of a submerged caldera that was formed by an explosive eruption. The caldera reaches a depth of ~225 meters, and has a prominent central cone or pinnacle that ascends within 20 meters of the sea surface. Our exploration of Maug began in 2003, when a single hydrocast in the caldera detected a strong suspended particle and helium plume reaching a maximum of δ3He = 250% at ~180 meters depth, clearly indicating hydrothermal activity within the caldera. In 2004 we returned armed with the ROPOS ROV, and two ROPOS dives discovered and sampled low temperature (~4 °C) diffuse venting associated with bacterial mats on the NE flank of the central pinnacle at 145 m depth. Samples collected with titanium gas tight bottles were badly diluted with ambient seawater but allowed an estimate of end-member 3He/4He of 7.3 Ra. Four vertical casts lowered into the caldera in 2004 all had a strong 3He signal (δ3He = 190%) at 150-190 meters depth. A recent expedition in 2014 focused on the shallow (~10 m) gas venting along the caldera interior. Scuba divers were able to collect samples of the gas bubbles using evacuated SS bottles fitted with plastic funnels. The gas samples had a consistent ~170 ppm He, 8 ppmNe, 60% CO2, 40%N2, and 0.8% Ar, and an end-member 3He/4He ratio of 6.9 Ra. This 3He/4He ratio falls within the range for typical arc volcanoes. The rather high atmospheric component (N2, Ar, Ne) in these samples is not contamination but appears to be derived from subsurface exchange between the ascending CO2 bubbles and air saturated seawater. A single vertical cast in 2014 had a maximum δ3He = 55% at 140 m depth, much lower than in 2003 and 2004. This decrease is possibly due to recent flushing of the caldera by a storm event, or may reflect a decrease in the deep hydrothermal activity. This area of shallow CO2 venting in Maug caldera is of particular interest as a natural laboratory for studying the effects of ocean acidification on corals.

Subseafloor Microbial Life in Venting Fluids from the Mid Cayman Rise Hydrothermal System

NASA Astrophysics Data System (ADS)

Huber, J. A.; Reveillaud, J.; Reddington, E.; McDermott, J. M.; Sylva, S. P.; Breier, J. A.; German, C. R.; Seewald, J.

2012-12-01

In hard rock seafloor environments, fluids emanating from hydrothermal vents are one of the best windows into the subseafloor and its resident microbial community. The functional consequences of an extensive population of microbes living in the subseafloor remains unknown, as does our understanding of how these organisms interact with one another and influence the biogeochemistry of the oceans. Here we report the abundance, activity, and diversity of microbes in venting fluids collected from two newly discovered deep-sea hydrothermal vents along the ultra-slow spreading Mid-Cayman Rise (MCR). Fluids for geochemical and microbial analysis were collected from the Von Damm and Piccard vent fields, which are located within 20 km of one another, yet have extremely different thermal, geological, and depth regimes. Geochemical data indicates that both fields are highly enriched in volatiles, in particular hydrogen and methane, important energy sources for and by-products of microbial metabolism. At both sites, total microbial cell counts in the fluids ranged in concentration from 5 x 10 4 to 3 x 10 5 cells ml-1 , with background seawater concentrations of 1-2 x 10 4 cells ml-1 . In addition, distinct cell morphologies and clusters of cells not visible in background seawater were seen, including large filaments and mineral particles colonized by microbial cells. These results indicate local enrichments of microbial communities in the venting fluids, distinct from background populations, and are consistent with previous enumerations of microbial cells in venting fluids. Stable isotope tracing experiments were used to detect utilization of acetate, formate, and dissolve inorganic carbon and generation of methane at 70 °C under anaerobic conditions. At Von Damm, a putatively ultra-mafic hosted site located at ~2200 m with a maximum temperature of 226 °C, stable isotope tracing experiments indicate methanogenesis is occurring in most fluid samples. No activity was detected in Piccard vent fluids, a basalt-hosted black smoker site located at ~4950 m with a maximum temperature of 403 °C. However, hyperthermophilic and thermophilic heterotrophs of the genus Thermococcus were isolated from Piccard vent fluids, but not Von Damm. These obligate anaerobes, growing optimally at 55-90 °C, are ubiquitous at hydrothermal systems and serve as a readily cultivable indicator organism of subseafloor populations. Finally, molecular analysis of vent fluids is on-going and will define the microbial population structure in this novel ecosystem and allow for direct comparisons with other deep-sea and subsurface habitats as part of our continuing efforts to explore the deep microbial biosphere on Earth.

Fossil evidence for serpentinization fluids fueling chemosynthetic assemblages

PubMed Central

Lartaud, Franck; Little, Crispin T. S.; de Rafelis, Marc; Bayon, Germain; Dyment, Jerome; Ildefonse, Benoit; Gressier, Vincent; Fouquet, Yves; Gaill, Françoise; Le Bris, Nadine

2011-01-01

Among the deep-sea hydrothermal vent sites discovered in the past 30 years, Lost City on the Mid-Atlantic Ridge (MAR) is remarkable both for its alkaline fluids derived from mantle rock serpentinization and the spectacular seafloor carbonate chimneys precipitated from these fluids. Despite high concentrations of reduced chemicals in the fluids, this unique example of a serpentinite-hosted hydrothermal system currently lacks chemosynthetic assemblages dominated by large animals typical of high-temperature vent sites. Here we report abundant specimens of chemosymbiotic mussels, associated with gastropods and chemosymbiotic clams, in approximately 100 kyr old Lost City-like carbonates from the MAR close to the Rainbow site (36 °N). Our finding shows that serpentinization-related fluids, unaffected by high-temperature hydrothermal circulation, can occur on-axis and are able to sustain high-biomass communities. The widespread occurrence of seafloor ultramafic rocks linked to likely long-range dispersion of vent species therefore offers considerably more ecospace for chemosynthetic fauna in the oceans than previously supposed. PMID:21518892

Fossil evidence for serpentinization fluids fueling chemosynthetic assemblages.

PubMed

Lartaud, Franck; Little, Crispin T S; de Rafelis, Marc; Bayon, Germain; Dyment, Jerome; Ildefonse, Benoit; Gressier, Vincent; Fouquet, Yves; Gaill, Françoise; Le Bris, Nadine

2011-05-10

Among the deep-sea hydrothermal vent sites discovered in the past 30 years, Lost City on the Mid-Atlantic Ridge (MAR) is remarkable both for its alkaline fluids derived from mantle rock serpentinization and the spectacular seafloor carbonate chimneys precipitated from these fluids. Despite high concentrations of reduced chemicals in the fluids, this unique example of a serpentinite-hosted hydrothermal system currently lacks chemosynthetic assemblages dominated by large animals typical of high-temperature vent sites. Here we report abundant specimens of chemosymbiotic mussels, associated with gastropods and chemosymbiotic clams, in approximately 100 kyr old Lost City-like carbonates from the MAR close to the Rainbow site (36 °N). Our finding shows that serpentinization-related fluids, unaffected by high-temperature hydrothermal circulation, can occur on-axis and are able to sustain high-biomass communities. The widespread occurrence of seafloor ultramafic rocks linked to likely long-range dispersion of vent species therefore offers considerably more ecospace for chemosynthetic fauna in the oceans than previously supposed.

Exploration and discovery in Yellowstone Lake: results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

NASA Astrophysics Data System (ADS)

Morgan, L. A.; Shanks, W. C.; Lovalvo, D. A.; Johnson, S. Y.; Stephenson, W. J.; Pierce, K. L.; Harlan, S. S.; Finn, C. A.; Lee, G.; Webring, M.; Schulze, B.; Dühn, J.; Sweeney, R.; Balistrieri, L.

2003-04-01

'No portion of the American continent is perhaps so rich in wonders as the Yellow Stone' (F.V. Hayden, September 2, 1874) Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (˜1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem.

Hydrogen isotope systematics of phase separation in submarine hydrothermal systems: Experimental calibration and theoretical models

USGS Publications Warehouse

Berndt, M.E.; Seal, R.R.; Shanks, Wayne C.; Seyfried, W.E.

1996-01-01

Hydrogen isotope fractionation factors were measured for coexisting brines and vapors formed by phase separation of NaCl/H2O fluids at temperatures ranging from 399-450??C and pressures from 277-397 bars. It was found that brines are depleted in D compared to coexisting vapors at all conditions studied. The magnitude of hydrogen isotope fractionation is dependent on the relative amounts of Cl in the two phases and can be empirically correlated to pressure using the following relationship: 1000 ln ??(vap-brine) = 2.54(??0.83) + 2.87(??0.69) x log (??P), where ??(vap-brine) is the fractionation factor and ??P is a pressure term representing distance from the critical curve in the NaCl/H2O system. The effect of phase separation on hydrogen isotope distribution in subseafloor hydrothermal systems depends on a number of factors, including whether phase separation is induced by heating at depth or by decompression of hydrothermal fluids ascending to the seafloor. Phase separation in most subseafloor systems appears to be a simple process driven by heating of seawater to conditions within the two-phase region, followed by segregation and entrainment of brine or vapor into a seawater dominated system. Resulting vent fluids exhibit large ranges in Cl concentration with no measurable effect on ??D. Possible exceptions to this include hydrothermal fluids venting at Axial and 9??N on the East Pacific Rise. High ??D values of low Cl fluids venting at Axial are consistent with phase separation taking place at relatively shallow levels in the oceanic crust while negative ??D values in some low Cl fluids venting at 9??N suggest involvement of a magmatic fluid component or phase separation of D-depleted brines derived during previous hydrothermal activity.

Ecology and biogeography of megafauna and macrofauna at the first known deep-sea hydrothermal vents on the ultraslow-spreading Southwest Indian Ridge

PubMed Central

Copley, J. T.; Marsh, L.; Glover, A. G.; Hühnerbach, V.; Nye, V. E.; Reid, W. D. K.; Sweeting, C. J.; Wigham, B. D.; Wiklund, H.

2016-01-01

The Southwest Indian Ridge is the longest section of very slow to ultraslow-spreading seafloor in the global mid-ocean ridge system, but the biogeography and ecology of its hydrothermal vent fauna are previously unknown. We collected 21 macro- and megafaunal taxa during the first Remotely Operated Vehicle dives to the Longqi vent field at 37° 47′S 49° 39′E, depth 2800 m. Six species are not yet known from other vents, while six other species are known from the Central Indian Ridge, and morphological and molecular analyses show that two further polychaete species are shared with vents beyond the Indian Ocean. Multivariate analysis of vent fauna across three oceans places Longqi in an Indian Ocean province of vent biogeography. Faunal zonation with increasing distance from vents is dominated by the gastropods Chrysomallon squamiferum and Gigantopelta aegis, mussel Bathymodiolus marisindicus, and Neolepas sp. stalked barnacle. Other taxa occur at lower abundance, in some cases contrasting with abundances at other vent fields, and δ13C and δ15N isotope values of species analysed from Longqi are similar to those of shared or related species elsewhere. This study provides baseline ecological observations prior to mineral exploration activities licensed at Longqi by the United Nations. PMID:27966649

Deposition of talc - kerolite-smectite - smectite at seafloor hydrothermal vent fields: Evidence from mineralogical, geochemical and oxygen isotope studies

USGS Publications Warehouse

Dekov, V.M.; Cuadros, J.; Shanks, Wayne C.; Koski, R.A.

2008-01-01

Talc, kerolite-smectite, smectite, chlorite-smectite and chlorite samples from sediments, chimneys and massive sulfides from six seafloor hydrothermal areas have been analyzed for mineralogy, chemistry and oxygen isotopes. Samples are from both peridotite- and basalt-hosted hydrothermal systems, and basaltic systems include sediment-free and sediment-covered sites. Mg-phyllosilicates at seafloor hydrothermal sites have previously been described as talc, stevensite or saponite. In contrast, new data show tri-octahedral Mg-phyllosilicates ranging from pure talc and Fe-rich talc, through kerolite-rich kerolite-smectite to smectite-rich kerolite-smectite and tri-octahedral smectite. The most common occurrence is mixed-layer kerolite-smectite, which shows an almost complete interstratification series with 5 to 85% smectitic layers. The smectite interstratified with kerolite is mostly tri-octahedral. The degree of crystal perfection of the clay sequence decreases generally from talc to kerolite-smectite with lower crystalline perfection as the proportion of smectite layers in kerolite-smectite increases. Our studies do not support any dependence of the precipitated minerals on the type/subtype of hydrothermal system. Oxygen isotope geothermometry demonstrates that talc and kerolite-smectite precipitated in chimneys, massive sulfide mounds, at the sediment surface and in open cracks in the sediment near seafloor are high-temperature (> 250????C) phases that are most probably the result of focused fluid discharge. The other end-member of this tri-octahedral Mg-phyllosilicate sequence, smectite, is a moderate-temperature (200-250????C) phase forming deep within the sediment (??? 0.8??m). Chlorite and chlorite-smectite, which constitute the alteration sediment matrix around the hydrothermal mounds, are lower-temperature (150-200????C) phases produced by diffuse fluid discharge through the sediment around the hydrothermal conduits. In addition to temperature, other two controls on the precipitation of this sequence are the silica activity and Mg/Al ratio (i.e. the degree of mixing of seawater with hydrothermal fluid). Higher silica activity favors the formation of talc relative to tri-octahedral smectite. Vent structures and sedimentary cover preclude complete mixing of hydrothermal fluid and ambient seawater, resulting in lower Mg/Al ratios in the interior parts of the chimneys and deeper in the sediment which leads to the precipitation of phyllosilicates with lower Mg contents. Talc and kerolite-smectite have very low trace- and rare earth element contents. Some exhibit a negative or flat Eu anomaly, which suggests Eu depletion in the original hydrothermal fluid. Such Eu depletion could be caused by precipitation of anhydrite or barite (sinks for Eu2+) deeper in the system. REE abundances and distribution patterns indicate that chlorite and chlorite-smectite are hydrothermal alteration products of the background turbiditic sediment. ?? 2007 Elsevier B.V. All rights reserved.

U-Th systematics and 230Th ages of carbonate chimneys at the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Ludwig, Kristin A.; Shen, Chuan-Chou; Kelley, Deborah S.; Cheng, Hai; Edwards, R. Lawrence

2011-04-01

The Lost City Hydrothermal Field (LCHF) is a serpentinite-hosted vent field located 15 km west of the spreading axis of the Mid-Atlantic Ridge. In this study, uranium-thorium (U-Th) geochronological techniques have been used to examine the U-Th systematics of hydrothermal fluids and the 230Th ages of hydrothermally-precipitated carbonate chimneys at the LCHF. Fluid sample analyses indicate that endmember fluids likely contain only 0.0073 ng/g U or less compared to 3.28 ± 0.03 ng/g of U in ambient seawater. For fluid samples containing only 2-21% ambient seawater (1.1-11 mmol/kg Mg), Th concentration is 0.11-0.13 pg/g and surrounding seawater concentrations average 0.133 ± 0.016 pg/g. The 230Th/ 232Th atomic ratios of the vent fluids range from 1 (±10) × 10 -6 to 11 (±5) × 10 -6, are less than those of seawater, and indicate that the vent fluids may contribute a minor amount of non-radiogenic 230Th to the LCHF carbonate chimney deposits. Chimney 238U concentrations range from 1 to 10 μg/g and the average chimney corrected initial δ 234U is 147.2 ± 0.8, which is not significantly different from the ambient seawater value of 146.5 ± 0.6. Carbonate 232Th concentrations range broadly from 0.0038 ± 0.0003 to 125 ± 16 ng/g and 230Th/ 232Th atomic ratios vary from near seawater values of 43 (±8) × 10 -6 up to 530 (±25) × 10 -3. Chimney ages, corrected for initial 230Th, range from 17 ± 6 yrs to 120 ± 13 kyrs. The youngest chimneys are at the intersection of two active, steeply-dipping normal faults that cut the Atlantis Massif; the oldest chimneys are located in the southwest portion of the field. Vent deposits on a steep, fault-bounded wall on the east side of the field are all <4 kyrs old, indicating that mass wasting in this region is relatively recent. Comparison of results to prior age-dating investigations of submarine hydrothermal systems shows that the LCHF is the most long-lived hydrothermal system known to date. It is likely that seismic activity and active faulting within the Atlantis Massif and the Atlantis Fracture Zone, coupled with volumetric expansion of the underlying serpentinized host rocks play major roles in sustaining hydrothermal activity at this site. The longevity of venting at the LCHF may have implications for ecological succession of microorganisms within serpentinite-hosted vent environments.

Discovery and Distribution of Black Smokers on the Western Galapagos Spreading Center: Implications for Spatial and Temporal Controls on High Temperature Venting at Ridge/Hotspot Intersections

NASA Astrophysics Data System (ADS)

Haymon, R. M.; Anderson, P. G.; Baker, E. T.; Resing, J. A.; White, S. M.; MacDonald, K. C.

2006-12-01

Though nearly one-fifth of the mid-ocean ridge (MOR) lies on or near hotspots, it has been debated whether hotspots increase or decrease MOR hydrothermal flux, or affect vent biota. Despite hotspot enhancement of melt supply, high-temperature vent plumes are enigmatically sparse along two previously-surveyed ridge- hotspot intersections [Reykjanes Ridge (RR), Southeast Indian Ridge (SEIR)]. This has been attributed to crustal thickening by excess volcanism. During the 2005-06 GalAPAGoS expedition, we conducted nested sonar, plume, and camera surveys along a 540 km-long portion of the Galapagos Spreading Center (GSC) where the ridge intersects the Galapagos hotspot at lon. 94.5 -89.5 deg. W. Although MOR hydrothermal springs were first found along the eastern GSC crest in 1977 near lon. 86 deg. W, the GalAPAGoS smokers are the first active high-temperature vents to be found anywhere along the Cocos-Nazca plate boundary. Active and/or recently-inactive smokers were located beneath plumes at 5 sites on the seafloor between lon. 91 deg. W and 94.5 deg. W (see Anderson et al., this session) during near-bottom, real-time fiber-optic Medea camera surveys. Smokers occur along eruptive seafloor fissures atop axial volcanic ridges near the middles of ridge segments, mainly in areas underlain by relatively shallow, continuous axial magma chamber (AMC) seismic reflectors. These findings (1) support magmatic, rather than tectonic, control of GSC smoker distribution; (2) demonstrate that thick crust at MOR-hotspot intersections does not prevent high-temperature hydrothermal vents from forming; and, (3) appear to be inconsistent with models suggesting that enhanced hydrothermal cooling causes abrupt deepening of the AMC and transition from non-rifted to rifted GSC morphology near lon. 92.7 deg. W. The widely-spaced smoker sites located on different GSC segments exhibit remarkably similar characteristics and seafloor settings. Most sites are mature or extinct, and are on lava flows of visually-similar ages (estimated to be tens-to-hundreds of years old). Possibly a volcanic pulse may have activated the hotspot- affected western GSC, and powered contemporaneous hydrothermal vents that now are waning. It may be that hotspots produce episodes of near-synchronous, extensive ridge volcanism and hydrothermal activity, followed by periods of quiescence. This idea is consistent with: the episodic eruption histories of Hawaii and Iceland; variably anomalous hydrothermal plume incidence (low on RR, SEIR, GSC; high on Mid-Atlantic Ridge near Azores hotspot); models of episodic melt extraction from mantle plumes; and evidence for magma propagation along hotspot-influenced ridges. Our hypothesis potentially can be tested by studies of gene flow between animal communities located on either side of the Galapagos hotspot, and by dating of GSC hydrothermal chimneys and the lava flows on which they are constructed.

Tide-related variability of TAG hydrothermal activity observed by deep-sea monitoring system and OBSH

NASA Astrophysics Data System (ADS)

Fujioka, Kantaro; Kobayashi, Kazuo; Kato, Kazuhiro; Aoki, Misumi; Mitsuzawa, Kyohiko; Kinoshita, Masataka; Nishizawa, Azusa

1997-12-01

Hydrothermal activities were monitored by an ocean bottom seismometer with hydrophone (OBSH) and a composite measuring system (Manatee) including CTD, current meter, transmission meter and cameras at a small depression on the TAG hydrothermal mound in the Mid-Atlantic Ridge. Low-frequency pressure pulses detected by the hydrophone with semi-diurnal periodicity seem to correspond to cycles of hydrothermal upflow from a small and short-lived smoker vent close to the observing site. The peaks of pressure pulses are synchronous with the maximum gradient of areal strain decrease due to tidal load release. Microearthquakes with very near epicenters occur sporadically and do not appear to be directly correlatable to hydrothermal venting. Temporal variations in bottom water temperature also have semi-diurnal periodicity but are more complicated than the pressure events. Temperatures may be affected both by upwelling of hot water and by lateral flow of the bottom current changing its directions with ocean tide.

Beyond the vent: New perspectives on hydrothermal plumes and pelagic biology

NASA Astrophysics Data System (ADS)

Phillips, Brennan T.

2017-03-01

Submarine hydrothermal vent fields introduce buoyant plumes of chemically altered seawater to the deep-sea water column. Chemoautotrophic microbes exploit this energy source, facilitating seafloor-based primary production that evidence suggests may transfer to pelagic consumers. While most hydrothermal plumes have relatively small volumes, there are recent examples of large-scale plume events associated with periods of eruptive activity, which have had a pronounced effect on water-column biology. This correlation suggests that hydrothermal plumes may have influenced basin-scale ocean chemistry during periods of increased submarine volcanism during the Phanerozoic eon. This paper synthesizes a growing body of scientific evidence supporting the hypothesis that hydrothermal plumes are the energetic basis of unique deep-sea pelagic food webs. While many important questions remain concerning the biology of hydrothermal plumes, this discussion is not present in ongoing management efforts related to seafloor massive sulfide (SMS) mining. Increased research efforts, focused on high-resolution surveys of midwater biology relative to plume structures, are recommended to establish baseline conditions and monitor the impact of future mining-based disturbances to the pelagic biosphere.

Advances in Taxonomy, Ecology, and Biogeography of Dirivultidae (Copepoda) Associated with Chemosynthetic Environments in the Deep Sea

PubMed Central

Gollner, Sabine; Ivanenko, Viatcheslav N.; Arbizu, Pedro Martínez; Bright, Monika

2010-01-01

Background Copepoda is one of the most prominent higher taxa with almost 80 described species at deep-sea hydrothermal vents. The unique copepod family Dirivultidae with currently 50 described species is the most species rich invertebrate family at hydrothermal vents. Methodology/Principal Findings We reviewed the literature of Dirivultidae and provide a complete key to species, and map geographical and habitat specific distribution. In addition we discuss the ecology and origin of this family. Conclusions/Significance Dirivultidae are only present at deep-sea hydrothermal vents and along the axial summit trough of midocean ridges, with the exception of Dirivultus dentaneus found associated with Lamellibrachia species at 1125 m depth off southern California. To our current knowledge Dirivultidae are unknown from shallow-water vents, seeps, whale falls, and wood falls. They are a prominent part of all communities at vents and in certain habitat types (like sulfide chimneys colonized by pompei worms) they are the most abundant animals. They are free-living on hard substrate, mostly found in aggregations of various foundation species (e.g. alvinellids, vestimentiferans, and bivalves). Most dirivultid species colonize more than one habitat type. Dirivultids have a world-wide distribution, but most genera and species are endemic to a single biogeographic region. Their origin is unclear yet, but immigration from other deep-sea chemosynthetic habitats (stepping stone hypothesis) or from the deep-sea sediments seems unlikely, since Dirivultidae are unknown from these environments. Dirivultidae is the most species rich family and thus can be considered the most successful taxon at deep-sea vents. PMID:20838422

Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity

PubMed Central

Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B.; Rouse, Greg; Salcedo, Diana L.; Soto, Luis A.; Zierenberg, Robert; Vrijenhoek, Robert

2017-01-01

Hydrothermal vent communities are distributed along mid-ocean spreading ridges as isolated patches. While distance is a key factor influencing connectivity among sites, habitat characteristics are also critical. The Pescadero Basin (PB) and Alarcón Rise (AR) vent fields, recently discovered in the southern Gulf of California, are bounded by previously known vent localities (e.g. Guaymas Basin and 21° N East Pacific Rise); yet, the newly discovered vents differ markedly in substrata and vent fluid attributes. Out of 116 macrofaunal species observed or collected, only three species are shared among all four vent fields, while 73 occur at only one locality. Foundation species at basalt-hosted sulfide chimneys on the AR differ from the functional equivalents inhabiting sediment-hosted carbonate chimneys in the PB, only 75 km away. The dominant species of symbiont-hosting tubeworms and clams, and peripheral suspension-feeding taxa, differ between the sites. Notably, the PB vents host a limited and specialized fauna in which 17 of 26 species are unknown at other regional vents and many are new species. Rare sightings and captured larvae of the ‘missing’ species revealed that dispersal limitation is not responsible for differences in community composition at the neighbouring vent localities. Instead, larval recruitment-limiting habitat suitability probably favours species differentially. As scenarios develop to design conservation strategies around mining of seafloor sulfide deposits, these results illustrate that models encompassing habitat characteristics are needed to predict metacommunity structure. PMID:28724734

Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity.

PubMed

Goffredi, Shana K; Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B; Rouse, Greg; Salcedo, Diana L; Soto, Luis A; Spelz-Madero, Ronald; Zierenberg, Robert; Vrijenhoek, Robert

2017-07-26

Hydrothermal vent communities are distributed along mid-ocean spreading ridges as isolated patches. While distance is a key factor influencing connectivity among sites, habitat characteristics are also critical. The Pescadero Basin (PB) and Alarcón Rise (AR) vent fields, recently discovered in the southern Gulf of California, are bounded by previously known vent localities (e.g. Guaymas Basin and 21° N East Pacific Rise); yet, the newly discovered vents differ markedly in substrata and vent fluid attributes. Out of 116 macrofaunal species observed or collected, only three species are shared among all four vent fields, while 73 occur at only one locality. Foundation species at basalt-hosted sulfide chimneys on the AR differ from the functional equivalents inhabiting sediment-hosted carbonate chimneys in the PB, only 75 km away. The dominant species of symbiont-hosting tubeworms and clams, and peripheral suspension-feeding taxa, differ between the sites. Notably, the PB vents host a limited and specialized fauna in which 17 of 26 species are unknown at other regional vents and many are new species. Rare sightings and captured larvae of the 'missing' species revealed that dispersal limitation is not responsible for differences in community composition at the neighbouring vent localities. Instead, larval recruitment-limiting habitat suitability probably favours species differentially. As scenarios develop to design conservation strategies around mining of seafloor sulfide deposits, these results illustrate that models encompassing habitat characteristics are needed to predict metacommunity structure. © 2017 The Authors.

Geologic map and geothermal assessment of the Mount Adams volcanic field, Cascade Range of southern Washington

USGS Publications Warehouse

Hildreth, Wes; Fierstein, Judy

1990-01-01

More than 60 Quaternary vents make up the basalt-to-rhyodacite Mount Adams volcanic field and have erupted scoriae and lavas with a total volume of >370 km3. The Mount Adams andesite-dacite stratocone itself is a compound edifice that includes the high cone above 2300 m (20-10 ka), remnants of at least two earlier andesite-dacite cones as old as 0.5 Ma, and 7 Holocene flank vents. Four other Holocene vents and tens of vents contemporaneous with Mount Adams are peripheral to the stratocone. All of these vents, including Mount Adams, lie within a N-S eruptive zone 55 km long and 5 km wide. The age of all known Mount Adams silicic products (>100 ka) and the heterogeneous mafic compositions of the summit cone and Holocene lavas make it unlikely that the stratocone is underlain by an upper-crustal reservoir. Rather, the stratocone at the focus is built up of fractionated hybrid magmas that rise from MASH zones (melting-assimilation-storage-homogenization). The pyroclastic core of breccia and scoria at Mount Adams has undergone acid-sulfate leaching and deposition of alunite, kaolinite, silica, gypsum, sulfur, and Fe-oxides and has been a constant source of avalanches and debris flows. Most heat supplied from depth to the fumarolically altered core is dispersed by the high precipitation rate and high permeability of the rubbly lava flows so that a hydrothermal convection pattern is not maintained. Summit-restricted fumaroles are weak and diffuse.

Physiological impacts of acute Cu exposure on deep-sea vent mussel Bathymodiolus azoricus under a deep-sea mining activity scenario.

PubMed

Martins, Inês; Goulart, Joana; Martins, Eva; Morales-Román, Rosa; Marín, Sergio; Riou, Virginie; Colaço, Ana; Bettencourt, Raul

2017-12-01

Over the past years, several studies have been dedicated to understanding the physiological ability of the vent mussel Bathymodiolus azoricus to overcome the high metal concentrations present in their surrounding hydrothermal environment. Potential deep-sea mining activities at Azores Triple junction hydrothermal vent deposits would inevitably lead to the emergence of new fluid sources close to mussel beds, with consequent emission of high metal concentrations and potential resolubilization of Cu from minerals formed during the active phase of the vent field. Copper is an essential metal playing a key role in the activation of metalloenzymes and metalloproteins responsible for important cellular metabolic processes and tissue homeostasis. However, excessive intracellular amounts of reactive Cu ions may cause irreversible damages triggering possible cell apoptosis. In the present study, B. azoricus was exposed to increasing concentrations of Cu for 96h in conditions of temperature and hydrostatic pressure similar to those experienced at the Lucky Strike hydrothermal vent field. Specimens were kept in 1L flasks, exposed to four Cu concentrations: 0μg/L (control), 300, 800 and 1600μg/L and pressurized to 1750bar. We addressed the question of how increased Cu concentration would affect the function of antioxidant defense proteins and expression of antioxidant and immune-related genes in B. azoricus. Both antioxidant enzymatic activities and gene expression were examined in gills, mantle and digestive gland tissues of exposed vent mussels. Our study reveals that stressful short-term Cu exposure has a strong effect on molecular metabolism of the hydrothermal vent mussel, especially in gill tissue. Initially, both the stress caused by unpressurization or by Cu exposure was associated with high antioxidant enzyme activities and tissue-specific transcriptional up-regulation. However, mussels exposed to increased Cu concentrations showed both antioxidant and immune-related gene suppression. Under a mining activity scenario, the release of an excess of dissolved Cu to the vent environment may cause serious changes in cellular defense mechanisms of B. azoricus. This outcome, while adding to our knowledge of Cu toxicity, highlights the potentially deleterious impacts of mining activities on the physiology of deep-sea organisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Major off-axis hydrothermal activity on the northern Gorda Ridge

USGS Publications Warehouse

Rona, Peter A.; Denlinger, Roger P.; Fisk, M. R.; Howard, K. J.; Taghon, G. L.; Klitgord, Kim D.; McClain, James S.; McMurray, G. R.; Wiltshire, J. C.

1990-01-01

The first hydrothermal field on the northern Gorda Ridge, the Sea Cliff hydrothermal field, was discovered and geologic controls of hydrothermal activity in the rift valley were investigated on a dive series using the DSV Sea Cliff. The Sea Cliff hydrothermal field was discovered where predicted at the intersection of axis-oblique and axis-parallel faults at the south end of a linear ridge at mid-depth (2700 m) on the east wall. Preliminary mapping and sampling of the field reveal: a setting nested on nearly sediment-free fault blocks 300 m above the rift valley floor 2.6 km from the axis; a spectrum of venting types from seeps to black smokers; high conductive heat flow estimated to be equivalent to the convective flux of multiple black smokers through areas of the sea floor sealed by a caprock of elastic breccia primarily derived from basalt with siliceous cement and barite pore fillings; and a vent biota with Juan de Fuca Ridge affinites. These findings demonstrate the importance of off-axis hydrothermal activity and the role of the intersection of tectonic lineations in controlling hydrothermal sites at sea-floor spreading centers.

Mathematical Models of Seafloor Hydrothermal Systems Driven by Serpentinization of Peridotite

NASA Astrophysics Data System (ADS)

Lowell, R. P.; Rona, P. A.; Germanovich, L. N.

2001-12-01

Most seafloor hydrothermal systems are driven by heat transfer from subsurface magma bodies. At slow spreading ridges of the Atlantic and Indian oceans, however, magma supply is low; and tectonic activity brings mantle rocks to shallow depths in the crust. Then, the heat of formation released upon serpentinization of peridotite provides the energy source for hydrothermal circulation. This latter class of system has been relatively unstudied, but recent discoveries of peridotite-hosted hydrothermal systems along the Mid-Atlantic Ridge suggest that such systems may play an important role in geochemical cycling and biogeochemical processes. The likelihood that peridotite-hosted hydrothermal systems was more prevalent during the Archean further suggests that such systems may have played a role in the origin of life. We present the first mathematical models of seafloor hydrothermal systems driven by heat released upon serpentinization of peridotite. We assume seawater circulates through a major crack network in the host-peridotite and that cooling of the host-rock leads to the formation of microcracks through which the fluid infiltrates. Reaction of the fluid in microcracks with the host rock results in serpentinization and the heat released upon serpentinization is transported to the seafloor by the fluid circulating in the main crack network. The temperature and heat output of the resulting hydrothermal system is a function of the main network permeability and the rate at which the serpentinization reaction proceeds via diffusion and propagation of the microcracks. Although the temperature of such a system can be quite variable, vent temperatures between 10° C and 100° C are likely for typical crustal parameters.

Origin of Abiotic Methane in Submarine Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Seewald, J. S.; German, C. R.; Grozeva, N. G.; Klein, F.; McDermott, J. M.; Ono, S.; Reeves, E. P.; Wang, D. T.

2018-05-01

Results of recent investigations into the chemical and isotopic composition of actively venting submarine hydrothermal fluids and volatile species trapped in fluid inclusions will be discussed in the context of processes responsible for abiotic CH4 formation.

Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.

1981-01-01

A study of the mineralogical changes associated with these hydrothermal vents was initiated with the aim of developing possible exploration tools for geothermal resources. The Cerro Prieto reservoir has already been explored by extensive deep drilling so that relationships between surface manifestations and deeper hydrothermal processes could be established directly. Approximately 120 samples of surface sediments were collected both inside and outside of the vents. The mineralogy of the altered sediments studied appears to be controlled by the type of emission. A comparison between the changes in mineralogy due to low temperature hydrothermal activity in the reservoir, seen in samplesmore » from boreholes, and mineralogical changes in the surface emission samples shows similar general trends below 180 C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristic products of the discharge from high intensity geothermal fields.« less

Water and the thermal evolution of carbonaceous chondrite parent bodies

NASA Technical Reports Server (NTRS)

Grimm, Robert E.; Mcsween, Harry Y., Jr.

1989-01-01

Two hypotheses are proposed for the aqueous alteration of carbonaceous chondrites within their parent bodies, in which respectively the alteration occurs (1) throughout the parent body interior, or (2) in a postaccretional surface regolith; both models assume an initially homogeneous mixture of ice and rock that is heated through the decay of Al-26. Water is seen to exert a powerful influence on chondrite evolution through its role of thermal buffer, permitting substitution of a low temperature aqueous alteration for high temperature recrystallization. It is quantitatively demonstrated that liquid water may be introduced by either hydrothermal circulation, vapor diffusion from below, or venting due to fracture.

Formation of Deep Sea Umber Deposits Linked to Microbial Metal Oxidation at the South Atlantic Ridge

NASA Astrophysics Data System (ADS)

Peng, Xiaotong; Ta, Kaiwen; Chen, Shun; Zhang, Lijuan; Xu, Hengchao

2015-04-01

Umber deposits are important metalliferous deposits, which occur in off-axis half-graben structures at ancient and modern ocean floor. The genesis of umber deposits has remained controversial for several decades. Recently, microbial Fe(II) oxidation associated with low-temperature diffuse venting has been identified as a key process for the formation of umber deposits, but the exact biochemical mechanisms involved to the precipitation of Mn oxides and co-precipitation of Fe oxyhydroxides and Mn oxides in umber deposits still remain unknown. Here, we used nano secondary ion mass spectrometer, synchrotron-based X-ray absorption spectroscopy, electron microscopy, and molecular techniques to demonstrate the coexistence of two types of metal-oxidizing bacteria within deep-sea hydrothermal umber deposits at the South Atlantic Ridge, where we found unique spheroids composed of biogenic Fe oxyhydroxides and Mn oxides in the deposits. Our data suggest that Fe oxyhydroxides and Mn oxides are metabolic by-products of lithotrophic Fe(II)-oxidizing bacteria and heterotrophic Mn(II)-oxidizing bacteria, respectively. The hydrothermal vents fuel lithotrophic Fe(II)-oxidizing bacteria, which constitute a trophic base that may support the activities of heterotrophic Mn(II)-oxidizing bacteria. The biological origin of umber deposits underscore the importance of geomicrobiologcial interaction in triggering the formation of deep-sea deposits, with important implications for the generation of submarine Mn deposits and crusts.

Spatial Differences in East Scotia Ridge Hydrothermal Vent Food Webs: Influences of Chemistry, Microbiology and Predation on Trophodynamics

PubMed Central

Reid, William D. K.; Sweeting, Christopher J.; Wigham, Ben D.; Zwirglmaier, Katrin; Hawkes, Jeffrey A.; McGill, Rona A. R.; Linse, Katrin; Polunin, Nicholas V. C.

2013-01-01

The hydrothermal vents on the East Scotia Ridge are the first to be explored in the Antarctic and are dominated by large peltospiroid gastropods, stalked barnacles (Vulcanolepas sp.) and anomuran crabs (Kiwa sp.) but their food webs are unknown. Vent fluid and macroconsumer samples were collected at three vent sites (E2, E9N and E9S) at distances of tens of metres to hundreds of kilometres apart with contrasting vent fluid chemistries to describe trophic interactions and identify potential carbon fixation pathways using stable isotopes. δ13C of dissolved inorganic carbon from vent fluids ranged from −4.6‰ to 0.8‰ at E2 and from −4.4‰ to 1.5‰ at E9. The lowest macroconsumer δ13C was observed in peltospiroid gastropods (−30.0‰ to −31.1‰) and indicated carbon fixation via the Calvin-Benson-Bassham (CBB) cycle by endosymbiotic gamma-Proteobacteria. Highest δ13C occurred in Kiwa sp. (−19.0‰ to −10.5‰), similar to that of the epibionts sampled from their ventral setae. Kiwa sp. δ13C differed among sites, which were attributed to spatial differences in the epibiont community and the relative contribution of carbon fixed via the reductive tricarboxylic acid (rTCA) and CBB cycles assimilated by Kiwa sp. Site differences in carbon fixation pathways were traced into higher trophic levels e.g. a stichasterid asteroid that predates on Kiwa sp. Sponges and anemones at the periphery of E2 assimilated a proportion of epipelagic photosynthetic primary production but this was not observed at E9N. Differences in the δ13C and δ34S values of vent macroconsumers between E2 and E9 sites suggest the relative contributions of photosynthetic and chemoautotrophic carbon fixation (rTCA v CBB) entering the hydrothermal vent food webs vary between the sites. PMID:23762393

Boiling vapour-type fluids from the Nifonea vent field (New Hebrides Back-Arc, Vanuatu, SW Pacific): Geochemistry of an early-stage, post-eruptive hydrothermal system

NASA Astrophysics Data System (ADS)

Schmidt, Katja; Garbe-Schönberg, Dieter; Hannington, Mark D.; Anderson, Melissa O.; Bühring, Benjamin; Haase, Karsten; Haruel, Christy; Lupton, John; Koschinsky, Andrea

2017-06-01

In 2013, high-temperature vent fluids were sampled in the Nifonea vent field. This field is located within the caldera of a large shield-type volcano of the Vate Trough, a young extensional rift in the New Hebrides back-arc. Hydrothermal venting occurs as clear and black smoker fluids with temperatures up to 368 °C, the hottest temperatures measured so far in the western Pacific. The physico-chemical conditions place the fluids within the two-phase field of NaCl-H2O, and venting is dominated by vapour phase fluids with Cl concentrations as low as 25 mM. The fluid composition, which differs between the individual vent sites, is interpreted to reflect the specific geochemical fluid signature of a hydrothermal system in its initial, post-eruptive stage. The strong Cl depletion is accompanied by low alkali/Cl ratios compared to more evolved hydrothermal systems, and very high Fe/Cl ratios. The concentrations of REY (180 nM) and As (21 μM) in the most Cl-depleted fluid are among the highest reported so far for submarine hydrothermal fluids, whereas the inter-element REY fractionation is only minor. The fluid signature, which has been described here for the first time in a back-arc setting, is controlled by fast fluid passage through basaltic volcanic rocks, with extremely high water-rock ratios and only limited water-rock exchange, phase separation and segregation, and (at least) two-component fluid mixing. Metals and metalloids are unexpectedly mobile in the vapour phase fluids, and the strong enrichments of Fe, REY, and As highlight the metal transport capacity of low-salinity, low-density vapours at the specific physico-chemical conditions at Nifonea. One possible scenario is that the fluids boiled before the separated vapour phase continued to react with fresh glassy lavas. The mobilization of metals is likely to occur by leaching from fresh glass and grain boundaries and is supported by the high water/rock ratios. The enrichment of B and As is further controlled by their high volatility, whereas the strong enrichment of REY is also a consequence of the elevated concentrations in the host rocks. However, a direct contribution of metals such as As from magmatic degassing cannot be ruled out. The different fluid end-member composition of individual vent sites could be explained by mixing of vapour phase fluids with another fluid phase of different water/rock interaction history.

Fossils of hydrothermal vent worms from Cretaceous sulfide ores of the Samail ophiolite, Oman

USGS Publications Warehouse

Haymon, R.M.; Koski, R.A.; Sinclair, C.

1984-01-01

Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

USGS Publications Warehouse

Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew R.; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

2012-01-01

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

PubMed

Taylor, Vivien F; Jackson, Brian P; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A; Kirshtein, Julie; Voytek, Mary

2012-05-04

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata , the vent chimney-dwelling mussel, Bathymodiolus azoricus , Branchipolynoe seepensis , a commensal worm of B. azoricus , and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ 13 C and δ 15 N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata , whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.

Continuing Evolution of the Hydrothermal System at the RIDGE2000 ISS, 9-10° N EPR: 1991-2004

NASA Astrophysics Data System (ADS)

von Damm, K. L.; Parker, C. M.; Beers, K. A.; Hyde, A. A.

2004-12-01

We have been studying the evolution of the chemical composition of the mid-ocean ridge (MOR) hydrothermal system on the East Pacific Rise from 9° 46-51'N since it was impacted by volcanic eruptions in 1991/2. We have been using the chemical and temperature data to infer the processes that are occurring subseafloor in the upper oceanic crust. As of March 2004, the chemical compositions of the vent fluids from this site have not yet stabilized. This observation is helping us to better understand not only the impact of magmatic events on these systems, but also the time scales on which they occur. Centered at the RIDGE2000 ISS "bull's-eye" at 9° 50'N we have noted a striking increase in the number of hydrothermal vents as well as in their measured fluid temperatures beginning after ~2000. In November 2003 we first noted the formation of a black smoker vent at the Tica site (measured T=342° C). In March 2004 we identified another new area of robust flow near the Bio9 vents at 9° 50'N, the 'Alvinellid Mat,' that we anticipate will form an additional black smoker to the three currently active at this site. In March 2004 we measured temperatures of 388° C in fluids from both the Bio9 and Bio9' smokers, putting them essentially on the two phase curve for seawater at this depth. For all of the Bio9 vents, as well as Tica, the fluids contain less than 300 mmoles/kg of Cl, approximately half the local seawater concentration. These high temperature and low Cl concentrations are accompanied by unusually low Si concentrations, <9.5 mmoles/kg. These data suggest a relatively shallow depth of reaction for the fluids, within a few hundred meters of the seafloor. These are the hottest temperatures measured in the Bio9 vents since the eruption in 1992. In contrast, the temperatures at P vent, about 60m south have cooled by ˜15° C since 2002. About 400m south, the chlorinity of the fluids from Ty and Io vents have increased, and Tube Worm Pillar, about 400m further south has become inactive. Therefore the changes in the vent fluids vary widely and often in opposite senses, over ˜1.5km of very hydrothermally active ridge. A more complete discussion of the changes and our interpretation of their implications for processes occurring subseafloor will be presented.

Numerical Modeling of Hydrothermal Circulation at the Longqi-1 Field: Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Guo, Z.; Lowell, R. P.; Tao, C.; Rupke, L.; Lewis, K. C.

2017-12-01

The Longqi-1(Dragon Flag) hydrothermal field is the first high-temperature hydrothermal system observed on the ultra-slow spreading Southwest Indian Ridge. Hydrothermal vents with temperatures near 380 °C are localized by detachment faulting within which extensional deformation likely increases permeability to provide preferred pathways for hydrothermal discharge. To better understand the Longqi-1 circulation system, we construct a 2-D numerical simulations in a NaCl- H2O fluid constrained by key observational data, such as vent temperature and heat output, crust structure derived from seismic data, and fault zone geometry deduced from seismicity. Heat output from AUV surveys is estimated to be » 300 ± 100 MW, and this value, in conjunction with vent temperature was used with the single-pass modeling approach to obtain an average permeability of 10-13 m-2 within the fault zone. In analogy with other fault-controlled hydrothermal systems such as Logatchev-1 we assume a lower background permeability of 10-14 m-2. The top boundary of the system is permeable and maintained at constant seafloor pressure, which is divided into two parts by the detachment fault. The pressure of the southern part is lower than the northern part to simulate the effect of the seafloor topography. The top boundary is upstream weighted to allow high temperature fluid to exit, while recharging fluid is maintained at 10°C. The bottom boundary is impermeable and is given a fixed temperature distribution at a depth of 7 km below the seafloor. The highest value Tmax is maintained over a distance given lateral distance and decreases linearly towards two ends to 300 °C. The salinity is set to 3.2 wt. % NaCl, and the simulations are assumed to be single phase. The results show that with a 7 km deep circulation system, Tmax = 550 oC gives a reasonable temperature and heat output of venting plume.We infer that the observed high salinity results from serpentinization reactions. Assuming all salinity in excess of seawater comes from uptake of H2O during serpentinization, we can estimate the rate of reaction and heat release of serpentinezation based on a simplified reaction equation, observed heat output and salinity data. The estimated rate of heat release during serpentinization is 20 MW. This is approximately 10% of the heat output of Dragon Flag vent field.

Deep-Sea Hydrothermal Vent Viruses Compensate for Microbial Metabolism in Virus-Host Interactions

PubMed Central

He, Tianliang; Li, Hongyun

2017-01-01

ABSTRACT Viruses are believed to be responsible for the mortality of host organisms. However, some recent investigations reveal that viruses may be essential for host survival. To date, it remains unclear whether viruses are beneficial or harmful to their hosts. To reveal the roles of viruses in the virus-host interactions, viromes and microbiomes of sediment samples from three deep-sea hydrothermal vents were explored in this study. To exclude the influence of exogenous DNAs on viromes, the virus particles were purified with nuclease (DNase I and RNase A) treatments and cesium chloride density gradient centrifugation. The metagenomic analysis of viromes without exogenous DNA contamination and microbiomes of vent samples indicated that viruses had compensation effects on the metabolisms of their host microorganisms. Viral genes not only participated in most of the microbial metabolic pathways but also formed branched pathways in microbial metabolisms, including pyrimidine metabolism; alanine, aspartate, and glutamate metabolism; nitrogen metabolism and assimilation pathways of the two-component system; selenocompound metabolism; aminoacyl-tRNA biosynthesis; and amino sugar and nucleotide sugar metabolism. As is well known, deep-sea hydrothermal vent ecosystems exist in relatively isolated environments which are barely influenced by other ecosystems. The metabolic compensation of hosts mediated by viruses might represent a very important aspect of virus-host interactions. PMID:28698277

U-Th isotopic systematics and ages of carbonate chimneys at the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Ludwig, K. A.; Shen, C.; Kelley, D. S.; Cheng, H.; Edwards, R.

2009-12-01

The Lost City Hydrothermal Field (LCHF) is a serpentinite-hosted vent field located 15 km west of the spreading axis of the Mid-Atlantic Ridge. In this study, uranium-thorium (U-Th) geochronological techniques have been used to examine the U-Th isotopic systematics of hydrothermal fluids and the 230Th ages of hydrothermally-precipitated carbonate chimneys at the LCHF. Fluid sample analyses indicate that endmember fluids likely contain only 0.0073 ng/g U or less compared to 3.28 ± 0.03 ng/g of U in ambient seawater. For fluid samples with <15 mmol/kg Mg, 232Th concentration is 0.11 to 0.13 pg/g and surrounding seawater concentration average is 0.133 ± 0.016 pg/g. The 230Th/232Th atomic ratios of the vent fluids range from 1 ± 10 to 26 ± 4 ×10-6 and are less than those of seawater. Chimney U is seawater-derived and 238U concentrations range from 1-10 μg/g and the mean chimney corrected initial δ234U is 146.9 ± 0.5, which is not significantly different from the ambient seawater value of 146.5 ± 0.6. Carbonate thorium concentrations range broadly from 0.035-125 ng/g and 230Th/232Th atomic ratios vary from near seawater values of 43 ± 8 × 10-6 up to 530 ± 25 × 10-3. Chimney ages range from 18 ± 6 yrs to 122 ± 12 kyrs. The youngest chimneys are at the intersection of two active, steeply-dipping normal faults that cut the Atlantis Massif; the oldest chimneys are located in the southwest portion of the field. Vent deposits on a steep, fault-bounded wall on the east side of the field are all <4 kyrs old, indicating that mass wasting in this region is relatively recent. Comparison of results to prior age-dating investigations of submarine hydrothermal systems shows that the LCHF is the most long-lived hydrothermal system known to date. It is likely that seismic activity and active faulting within the Atlantis Massif and the Atlantis Fracture Zone, coupled with volumetric expansion of the underlying serpentinized host rocks play major roles in sustaining hydrothermal activity at this site. The longevity of venting at the LCHF may have implications for ecological succession of microorganisms within serpentinite-hosted vent environments.

Alkaline Hydrothermal Vents as Electrochemical Reactors Driving an Auto-Trophic Origin of Life

NASA Astrophysics Data System (ADS)

Camprubi, E.; Lane, N.

2017-07-01

We report the reduction of CO2 to formaldehyde under simulated alkaline hydrothermal conditions. Formaldehyde is transformed into relevant sugars via the formose reaction. Acetyl phosphate can also be synthesised and phosphorylates organic molecules.

A novel microbial habitat in the mid-ocean ridge subseafloor

PubMed Central

Summit, Melanie; Baross, John A.

2001-01-01

The subseafloor at the mid-ocean ridge is predicted to be an excellent microbial habitat, because there is abundant space, fluid flow, and geochemical energy in the porous, hydrothermally influenced oceanic crust. These characteristics also make it a good analog for potential subsurface extraterrestrial habitats. Subseafloor environments created by the mixing of hot hydrothermal fluids and seawater are predicted to be particularly energy-rich, and hyperthermophilic microorganisms that broadly reflect such predictions are ejected from these systems in low-temperature (≈15°C), basalt-hosted diffuse effluents. Seven hyperthermophilic heterotrophs isolated from low-temperature diffuse fluids exiting the basaltic crust in and near two hydrothermal vent fields on the Endeavour Segment, Juan de Fuca Ridge, were compared phylogenetically and physiologically to six similarly enriched hyperthermophiles from samples associated with seafloor metal sulfide structures. The 13 organisms fell into four distinct groups: one group of two organisms corresponding to the genus Pyrococcus and three groups corresponding to the genus Thermococcus. Of these three groups, one was composed solely of sulfide-derived organisms, and the other two related groups were composed of subseafloor organisms. There was no evidence of restricted exchange of organisms between sulfide and subseafloor habitats, and therefore this phylogenetic distinction indicates a selective force operating between the two habitats. Hypotheses regarding the habitat differences were generated through comparison of the physiology of the two groups of hyperthermophiles; some potential differences between these habitats include fluid flow stability, metal ion concentrations, and sources of complex organic matter. PMID:11226209

High resolution mapping of hydrothermal plumes in the Mariana back-arc relate seafloor sources to above-bottom plumes

NASA Astrophysics Data System (ADS)

Walker, S. L.; Baker, E. T.; Resing, J. A.; Chadwick, W. W., Jr.; Merle, S. G.; Kaiser, C. L.

2016-12-01

The Mariana backarc spreading center between 12.9°-18°N was systematically explored for hydrothermal activity in Nov-Dec 2015 (R/V Falkor cruise FK151121) by conducting long distance along-axis CTD tows (vertical range was 20-600 meters above bottom (mab)) followed by higher resolution, horizontal grid AUV Sentry surveys at 70 mab in some of the areas where plumes were found. In those areas, the combination of along-axis CTD tows and near-bottom AUV surveys provides a nearly 3-dimensional view of the above-bottom plume relative to the seafloor morphology and potential sources. In addition, photo surveys were run at 5 mab at two of the sites. At 15.4°N, strong ORP anomalies (ΔE=-39 mv) with weak to absent optical signals were aligned with a new (<3yr) lava flow, suggesting widespread diffuse venting was associated with still-cooling lava to create a broad, optically weak plume that extended to 500 mab. About 10 km north of the new lava flow (15.5°N) there were fewer, but more distinct instances where temperature, particle, and OPR anomalies were co-located at 70 mab, providing information for the likely locations where more focused, higher temperature venting generated an optically intense (dNTU=0.032) above-bottom plume (to 500 mab over the axial high). The plume over the backarc segment high at 17.0°N exhibited a significant optical anomaly (dNTU=0.023) with a very strong ORP anomaly (ΔE=-88 mv) that extended only 1.5 km along-axis. The near-bottom survey showed a broad area ( 3km2) with robust temperature, particle, and ORP signals. Directed by this information, and the high resolution bathymetry acquired from the AUV survey, several active chimneys (one being 30 m tall with temperatures up to 340°C) were found during NOAA Okeanos Explorer ROV dives in May 2016. At 18°N, anomalies seen in the 11 km2 AUV survey were generally located along the axis of the spreading center and, with one exception, were limited to areas of previously-known (1987) venting. The plume in the water column over the Burke vent site was defined by both particle (dNTU=0.010) and ORP (ΔE=-11 mv) anomalies from 400-800 mab, but only ORP signals 120-400 mab. ORP signals were seen over the other sites without any optical anomalies; the much lower rise heights (200-400 mab) suggest only lower temperature, diffuse venting persists at these sites.

High-Resolution Geologic Mapping in the Eastern Manus Basin

NASA Astrophysics Data System (ADS)

Thal, J.; Bach, W.; Tivey, M.; Yoerger, D. R.

2011-12-01

AUV-based microbathymetry combined with ROV video data was used to create the first high-resolution geologic maps of two hydrothermal active areas in the eastern Manus Basin: North Su volcano and PACManus hydrothermal field on Pual Ridge. The data were recorded in 2006 and 2011 during the research cruises Magellan-06 operated by the Woods Hole Oceanographic Institution and BAMBUS (SO-216) operated by MARUM / University Bremen. High accuracy underwater navigation transponder-based and Posidonia systems allowed us to combine video data with bathymetry. The navigation on both cruises was very precise (m-scale) and navigation offsets were less than 10 m. We conducted detailed geologic mapping and sampling to identify the seafloor volcanic and hydrothermal features and created highly detailed maps that provide a comprehensive picture of the seafloor and vent distribution in the eastern Manus Basin. Several different types of dacite lava morphology were mapped, including pillow lava, lobate flows and massive block lava. We have compiled all available information on rock chemistry, fluid and temperature measurements, video data, bathymetry and navigation data into a GIS database. We find that, in contrast to the tectonic control on vent distribution at slow spreading mid-ocean ridges, the pathways of upwelling hydrothermal vent fluids at PACManus are dominated by volcanic features, such as lava domes and thick, massive block lava flows. Vent fields are developed preferentially along the margins of major flow units, probably because the cores of these units are impermeable to fluid flow, while the autobrecciated outer parts of the flows are not. In the North Su area, a comparison of seafloor maps from 2006 and 2011 reveals recent volcanic activity, which has strongly modified the bathymetry and hydrothermal vent distribution on the southern flank of the volcano. An ash cone with multiple small craters on the SW flank of the North-Su volcano that didn't exist in 2006 was mapped in 2011. Also, magmatic degassing was much more vigorous in 2011, with large accumulations of liquid sulfur (from disproportionation of magmatic SO2) as well as extensive bubbling of supercritical and liquid CO2.

Using CO2 and He Concentrations in Hydrothermal Fluids to Constrain Along-Axis Magma Chamber Dimensions at 9°N, EPR

NASA Astrophysics Data System (ADS)

Lilley, M. D.; Lupton, J. E.; Olson, E. J.

2002-12-01

Magmatic degassing is a common occurrence in subaerial volcanoes and has been reported in shallow submarine volcanoes. It has been speculated that mid-ocean ridge magma chambers may exhibit degassing behavior but to date there has been no direct documentation of its occurrence. Based on very high CO2 and He concentrations, we believe that we now have evidence for a degassing magma chamber at 9°N, East Pacific Rise. M Vent, in the immediate vicinity of the 1991 eruption, exhibited high and relatively stable CO2 concentrations in excess of 150 mmol/kg for at least eight years post-eruption. Such high values are many times the value that can be extracted from basalt by hydrothermal fluid and have previously been seen only at Axial and Loihi Seamounts. Two vents about one km south (Bio 9 and P Vents) had CO2 concentrations around 50 mmol/kg in 1991 which increased to maxima near 200 mmol/kg in 1993. We believe this represents a southward movement of the magma body in this area. He concentrations were also elevated at all the vents but showed different temporal trends from CO2 and reached maximum values in 1994. 3He/heat ratios are significantly different between M and Bio 9 and P Vents implying that separate magma bodies with differing degrees of degassing underlie the two areas. We have seen similarly high concentrations of CO2 and He at 31.8°S on the East Pacific Rise (Lupton et al., 1999) and suggest that magmatic degassing into the hydrothermal convection cell is occurring there as well. This work indicates that the concentrations of magmatic gases in hydrothermal fluids may provide fine scale data bearing on the locations and along-axis dimensions of magma chambers. Reference: Lupton, J., D. Butterfield, M. Lilley, J. Ishibashi, D. Hey and L. Evans, Gas chemistry of hydrothermal fluids along the East Pacific Rise, 5°S to 32°S, EOS, 80, F1099, 1999.

REE controls in ultramafic hosted MOR hydrothermal systems: An experimental study at elevated temperature and pressure

NASA Astrophysics Data System (ADS)

Allen, Douglas E.; Seyfried, W. E.

2005-02-01

A hydrothermal experiment involving peridotite and a coexisting aqueous fluid was conducted to assess the role of dissolved Cl - and redox on REE mobility at 400°C, 500 bars. Data show that the onset of reducing conditions enhances the stability of soluble Eu +2 species. Moreover, Eu +2 forms strong aqueous complexes with dissolved Cl - at virtually all redox conditions. Thus, high Cl - concentrations and reducing conditions can combine to reinforce Eu mobility. Except for La, trivalent REE are not greatly affected by fluid speciation under the chemical and physical condition considered, suggesting control by secondary mineral-fluid partitioning. LREE enrichment and positive Eu anomalies observed in fluids from the experiment are remarkably similar to patterns of REE mobility in vent fluids issuing from basalt- and peridotite-hosted hydrothermal systems. This suggests that the chondrite normalized REE patterns are influenced greatly by fluid speciation effects and secondary mineral formation processes. Accordingly, caution must be exercised when using REE in hydrothermal vent fluids to infer REE sources in subseafloor reaction zones from which the fluids are derived. Although vent fluid patterns having LREE enrichment and positive Eu anomalies are typically interpreted to suggest plagioclase recrystallization reactions, this need not always be the case.

Seismological evidence for an along-axis hydrothermal flow at the Lucky Strike hydrothermal vents site

NASA Astrophysics Data System (ADS)

Rai, A.; Wang, H.; Singh, S. C.; Crawford, W. C.; Escartin, J.; Cannat, M.

2010-12-01

Hydrothermal circulation at ocean spreading centres plays fundamental role in crustal accretion process, heat extraction from the earth and helps to maintain very rich ecosystem in deep Ocean. Recently, it has been suggested that hydrothermal circulation is mainly along the ridge axis at fast spreading centres above along axis melt lens (AMC). Using a combination of micro-earthquake and seismic reflection data, we show that the hydrothermal circulation at the Lucky Strike segment of slow spreading Mid-Atlantic Ridge is also along axis in a narrow (~1 km) zone above a wide (2-3 km) AMC. We find that the seismicity mainly lies above the seismically imaged 3 km wide 7 km long melt lens at 3.2 km depth. We observe a vertical plume of seismicity above a weak AMC reflection just north of the hydrothermal vent fields that initiates just above the AMC and continues to the seafloor. This zone is collocated with active rifting of the seafloor in the neo-volcanic zone. Beneath the hydrothermal vents sites, where a strong melt lens is imaged, the seismicity initiates at 500 m above the AMC and continues to the seafloor. Just south of the hydrothermal field, where the AMC is widest and strongest, the seismicity band lies 500 m above the melt lens in a 800 m thick zone, which does not continue to the seafloor. The presence the weak melt lens reflection could be due to a cooled and crystallised AMC (mush) that permits the penetration of hydrothermal fluids down to the top of the AMC indicated by seismicity plume and might be the in-flow zone for hydrothermal circulation. The strong AMC reflection could be due to fresh supply of melt in the AMC (pure melt), which has pushed the cracking front 500 m above the AMC. Beneath the hydrothermal fields, the strong AMC reflection and seismicity 500 above the AMC to the seafloor could represent cracking along the up-flow zone. The 800 m thick zone of seismicity above the pure melt zone could be the zone of hydrothermal cracking zone. We do not observe any seismicity along the main bounding faults. These results suggest that the hydrothermal flow is mainly along the ridge axis in a narrow zone above the AMC, even when the AMC only 7 km long.

Acquisition of epibiotic bacteria along the life cycle of the hydrothermal shrimp Rimicaris exoculata.

PubMed

Guri, Mathieu; Durand, Lucile; Cueff-Gauchard, Valérie; Zbinden, Magali; Crassous, Philippe; Shillito, Bruce; Cambon-Bonavita, Marie-Anne

2012-03-01

The caridean shrimp Rimicaris exoculata dominates the fauna at several Mid-Atlantic Ridge hydrothermal vent sites. This shrimp has an enlarged gill chamber, harboring a dense ectosymbiotic community of chemoautotrophic bacteria associated with mineral oxide deposits. Until now, their acquisition is not fully understood. At three hydrothermal vent sites, we analyzed the epibionts diversity at different moult stages and also in the first stages of the shrimp life (eggs, hatched eggs (with larvae) and juveniles). Hatched eggs associated with young larvae were collected for the first time directly from gravid females at the Logachev vent site during the Serpentine cruise. An approach using 16S rRNA clone libraries, scanning and transmission electron microscopy, and fluorescent in situ hybridization was used. Molecular results and microscope observations indicated a switch in the composition of the bacterial community between early R. exoculata life cycle stage (egg libraries dominated by the Gammaproteobacteria) and later stages (juvenile/adult libraries dominated by the Epsilonproteobacteria). We hypothesized that the epibiotic phylotype composition could vary according to the life stage of the shrimp. Our results confirmed the occurrence of a symbiosis with Gammaproteobacteria and Epsilonproteobacteria, but more complex than previously assumed. We revealed the presence of active type-I methanotrophic bacteria colonizing the cephalothorax of shrimps from the Rainbow site. They were also present on the eggs from the Logachev site. This could be the first 'epibiotic' association between methanotrophic bacteria and hydrothermal vent crustacean. We discuss possible transmission pathways for epibionts linked to the shrimp life cycle.

Acquisition of epibiotic bacteria along the life cycle of the hydrothermal shrimp Rimicaris exoculata

PubMed Central

Guri, Mathieu; Durand, Lucile; Cueff-Gauchard, Valérie; Zbinden, Magali; Crassous, Philippe; Shillito, Bruce; Cambon-Bonavita, Marie-Anne

2012-01-01

The caridean shrimp Rimicaris exoculata dominates the fauna at several Mid-Atlantic Ridge hydrothermal vent sites. This shrimp has an enlarged gill chamber, harboring a dense ectosymbiotic community of chemoautotrophic bacteria associated with mineral oxide deposits. Until now, their acquisition is not fully understood. At three hydrothermal vent sites, we analyzed the epibionts diversity at different moult stages and also in the first stages of the shrimp life (eggs, hatched eggs (with larvae) and juveniles). Hatched eggs associated with young larvae were collected for the first time directly from gravid females at the Logachev vent site during the Serpentine cruise. An approach using 16S rRNA clone libraries, scanning and transmission electron microscopy, and fluorescent in situ hybridization was used. Molecular results and microscope observations indicated a switch in the composition of the bacterial community between early R. exoculata life cycle stage (egg libraries dominated by the Gammaproteobacteria) and later stages (juvenile/adult libraries dominated by the Epsilonproteobacteria). We hypothesized that the epibiotic phylotype composition could vary according to the life stage of the shrimp. Our results confirmed the occurrence of a symbiosis with Gammaproteobacteria and Epsilonproteobacteria, but more complex than previously assumed. We revealed the presence of active type-I methanotrophic bacteria colonizing the cephalothorax of shrimps from the Rainbow site. They were also present on the eggs from the Logachev site. This could be the first ‘epibiotic' association between methanotrophic bacteria and hydrothermal vent crustacean. We discuss possible transmission pathways for epibionts linked to the shrimp life cycle. PMID:21993397

Predicting the response of the deep-ocean microbiome to geochemical perturbations by hydrothermal vents.

PubMed

Reed, Daniel C; Breier, John A; Jiang, Houshuo; Anantharaman, Karthik; Klausmeier, Christopher A; Toner, Brandy M; Hancock, Cathrine; Speer, Kevin; Thurnherr, Andreas M; Dick, Gregory J

2015-08-01

Submarine hydrothermal vents perturb the deep-ocean microbiome by injecting reduced chemical species into the water column that act as an energy source for chemosynthetic organisms. These systems thus provide excellent natural laboratories for studying the response of microbial communities to shifts in marine geochemistry. The present study explores the processes that regulate coupled microbial-geochemical dynamics in hydrothermal plumes by means of a novel mathematical model, which combines thermodynamics, growth and reaction kinetics, and transport processes derived from a fluid dynamics model. Simulations of a plume located in the ABE vent field of the Lau basin were able to reproduce metagenomic observations well and demonstrated that the magnitude of primary production and rate of autotrophic growth are largely regulated by the energetics of metabolisms and the availability of electron donors, as opposed to kinetic parameters. Ambient seawater was the dominant source of microbes to the plume and sulphur oxidisers constituted almost 90% of the modelled community in the neutrally-buoyant plume. Data from drifters deployed in the region allowed the different time scales of metabolisms to be cast in a spatial context, which demonstrated spatial succession in the microbial community. While growth was shown to occur over distances of tens of kilometers, microbes persisted over hundreds of kilometers. Given that high-temperature hydrothermal systems are found less than 100 km apart on average, plumes may act as important vectors between different vent fields and other environments that are hospitable to similar organisms, such as oil spills and oxygen minimum zones.

Predicting the response of the deep-ocean microbiome to geochemical perturbations by hydrothermal vents

PubMed Central

Reed, Daniel C; Breier, John A; Jiang, Houshuo; Anantharaman, Karthik; Klausmeier, Christopher A; Toner, Brandy M; Hancock, Cathrine; Speer, Kevin; Thurnherr, Andreas M; Dick, Gregory J

2015-01-01

Submarine hydrothermal vents perturb the deep-ocean microbiome by injecting reduced chemical species into the water column that act as an energy source for chemosynthetic organisms. These systems thus provide excellent natural laboratories for studying the response of microbial communities to shifts in marine geochemistry. The present study explores the processes that regulate coupled microbial-geochemical dynamics in hydrothermal plumes by means of a novel mathematical model, which combines thermodynamics, growth and reaction kinetics, and transport processes derived from a fluid dynamics model. Simulations of a plume located in the ABE vent field of the Lau basin were able to reproduce metagenomic observations well and demonstrated that the magnitude of primary production and rate of autotrophic growth are largely regulated by the energetics of metabolisms and the availability of electron donors, as opposed to kinetic parameters. Ambient seawater was the dominant source of microbes to the plume and sulphur oxidisers constituted almost 90% of the modelled community in the neutrally-buoyant plume. Data from drifters deployed in the region allowed the different time scales of metabolisms to be cast in a spatial context, which demonstrated spatial succession in the microbial community. While growth was shown to occur over distances of tens of kilometers, microbes persisted over hundreds of kilometers. Given that high-temperature hydrothermal systems are found less than 100 km apart on average, plumes may act as important vectors between different vent fields and other environments that are hospitable to similar organisms, such as oil spills and oxygen minimum zones. PMID:25658053

High-throughput sequencing and analysis of the gill tissue transcriptome from the deep-sea hydrothermal vent mussel Bathymodiolus azoricus

PubMed Central

2010-01-01

Background Bathymodiolus azoricus is a deep-sea hydrothermal vent mussel found in association with large faunal communities living in chemosynthetic environments at the bottom of the sea floor near the Azores Islands. Investigation of the exceptional physiological reactions that vent mussels have adopted in their habitat, including responses to environmental microbes, remains a difficult challenge for deep-sea biologists. In an attempt to reveal genes potentially involved in the deep-sea mussel innate immunity we carried out a high-throughput sequence analysis of freshly collected B. azoricus transcriptome using gills tissues as the primary source of immune transcripts given its strategic role in filtering the surrounding waterborne potentially infectious microorganisms. Additionally, a substantial EST data set was produced and from which a comprehensive collection of genes coding for putative proteins was organized in a dedicated database, "DeepSeaVent" the first deep-sea vent animal transcriptome database based on the 454 pyrosequencing technology. Results A normalized cDNA library from gills tissue was sequenced in a full 454 GS-FLX run, producing 778,996 sequencing reads. Assembly of the high quality reads resulted in 75,407 contigs of which 3,071 were singletons. A total of 39,425 transcripts were conceptually translated into amino-sequences of which 22,023 matched known proteins in the NCBI non-redundant protein database, 15,839 revealed conserved protein domains through InterPro functional classification and 9,584 were assigned with Gene Ontology terms. Queries conducted within the database enabled the identification of genes putatively involved in immune and inflammatory reactions which had not been previously evidenced in the vent mussel. Their physical counterpart was confirmed by semi-quantitative quantitative Reverse-Transcription-Polymerase Chain Reactions (RT-PCR) and their RNA transcription level by quantitative PCR (qPCR) experiments. Conclusions We have established the first tissue transcriptional analysis of a deep-sea hydrothermal vent animal and generated a searchable catalog of genes that provides a direct method of identifying and retrieving vast numbers of novel coding sequences which can be applied in gene expression profiling experiments from a non-conventional model organism. This provides the most comprehensive sequence resource for identifying novel genes currently available for a deep-sea vent organism, in particular, genes putatively involved in immune and inflammatory reactions in vent mussels. The characterization of the B. azoricus transcriptome will facilitate research into biological processes underlying physiological adaptations to hydrothermal vent environments and will provide a basis for expanding our understanding of genes putatively involved in adaptations processes during post-capture long term acclimatization experiments, at "sea-level" conditions, using B. azoricus as a model organism. PMID:20937131

Refining the Subseafloor Circulation Model of the Middle Valley Hydrothermal System Using Fluid Geochemistry

NASA Astrophysics Data System (ADS)

Inderbitzen, K. E.; Wheat, C. G.; Baker, P. A.; Fisher, A. T.

2014-12-01

Currently, fluid circulation patterns and the evolution of rock/fluid compositions as circulation occurs in subseafloor hydrothermal systems are poorly constrained. Sedimented spreading centers provide a unique opportunity to study subsurface flow because sediment acts as an insulating blanket that traps heat from the cooling magma body and limits: (a) potential flow paths for seawater to recharge the aquifer in permeable upper basaltic basement and (b) points of altered fluid egress. This also allows for a range of thermal and geochemical gradients to exist near the sediment-water interface. Models of fluid circulation patterns in this type of hydrologic setting have been generated (eg. Stein and Fisher, 2001); however fluid chemistry datasets have not previously been used to test the model's viability. We address this issue by integrating the existing circulation model with fluid compositional data collected from sediment pore waters and high temperature hydrothermal vents located in Middle Valley on the Juan de Fuca Ridge. Middle Valley hosts a variety of hydrologic regimes: including areas of fluid recharge (Site 855), active venting (Site 858/1036; Dead Dog vent field), recent venting (Site 856/1035; Bent Hill Massive Sulfide deposit) and a section of heavily sedimented basement located between recharge and discharge sites (Site 857). We will present new results based on thermal and geochemical data from the area of active venting (Sites 858 and 1036), that was collected during Ocean Drilling Program Legs 139 and 169 and a subsequent heat flow/gravity coring effort. These results illuminate fine scale controls on secondary recharge and fluid flow within the sediment section at Site 858/1036. The current status of high temperature vents in this area (based on observations made in July, 2014) will also be outlined.

The relative effects of particles and turbulence on acoustic scattering from deep-sea hydrothermal vent plumes.

PubMed

Xu, Guangyu; Di Iorio, Daniela

2011-10-01

Acoustic methods are applied to the investigation and monitoring of a vigorous hydrothermal plume within the Main Endeavor vent field at the Endeavor segment of the Juan de Fuca Ridge. Forward propagation and scattering from suspended particulates using Rayleigh scattering theory is shown to be negligible (log-amplitude variance σ(χ) (2)~10(-7)) compared to turbulence induced by temperature fluctuations (σ(χ) (2)~0.1). The backscattering from turbulence is then quantified using the forward scattering derived turbulence level, which gives a volume backscattering strength of s(V)=6.5 × 10(-8) m(-1). The volume backscattering cross section from particulates can range from s(V)=3.3 × 10(-6) to 7.2 × 10(-10) m(-1) depending on the particle size. These results show that forward scatter acoustic methods in hydrothermal vent applications can be used to quantify turbulence and its effect on backscatter measurements, which can be a dominant factor depending on the particle size and its location within the plume. © 2011 Acoustical Society of America

The resistance to ionizing radiation of hyperthermophilic archaea isolated from deep-sea hydrothermal vents

NASA Astrophysics Data System (ADS)

Jolivet, E.; L'Haridon, S.; Corre, E.; Gérard, E.; Myllykallio, H.; Forterre, P.; Prieur, D.

2001-08-01

In this paper we present many results on radioresistance of hyperthermophilic archaeon isolated from deep-sea hydrothermal vents. Effects of gamma (γ) irradiation was first tested with Pyrococcus abyssi and showed that this micro-organism did not show any loss of viability until 2 kGy of γ-irradiation. Pulse Field Gel Electrophoresis (PFGE) analysis conducted with different species belonging to Archaea and Bacteria suggest that no specific DNA protection system exist that could explain the radioresistance of P. abyssi. Moreover, the genomic DNA completely fragmented after 2 kGy is fully restored in vivo under optimal growth conditions. The DNA replication or irradiated cells at 2,5 kGy is delayed by a lag phase which could coincide to this DNA repair. An associated mechanism of DNA repair by excision could act with the recombinational DNA repair. In parallel to these studies three hyperthermophilic archaeons highly resistant to ionizing radiation were isolated from deep-sea hydrothermal vents after the enrichment cultures were submitted to elevated irradiation doses (up to 20 and 30 kGy). All these novel species were more radioresistant than P. abyssi.

Volatile emissions and gas geochemistry of Hot Spring Basin, Yellowstone National Park, USA

USGS Publications Warehouse

Werner, C.; Hurwitz, S.; Evans, William C.; Lowenstern, J. B.; Bergfeld, D.; Heasler, H.; Jaworowski, C.; Hunt, A.

2008-01-01

We characterize and quantify volatile emissions at Hot Spring Basin (HSB), a large acid-sulfate region that lies just outside the northeastern edge of the 640??ka Yellowstone Caldera. Relative to other thermal areas in Yellowstone, HSB gases are rich in He and H2, and mildly enriched in CH4 and H2S. Gas compositions are consistent with boiling directly off a deep geothermal liquid at depth as it migrates toward the surface. This fluid, and the gases evolved from it, carries geochemical signatures of magmatic volatiles and water-rock reactions with multiple crustal sources, including limestones or quartz-rich sediments with low K/U (or 40*Ar/4*He). Variations in gas chemistry across the region reflect reservoir heterogeneity and variable degrees of boiling. Gas-geothermometer temperatures approach 300????C and suggest that the reservoir feeding HSB is one of the hottest at Yellowstone. Diffuse CO2 flux in the western basin of HSB, as measured by accumulation-chamber methods, is similar in magnitude to other acid-sulfate areas of Yellowstone and is well correlated to shallow soil temperatures. The extrapolation of diffuse CO2 fluxes across all the thermal/altered area suggests that 410 ?? 140??t d- 1 CO2 are emitted at HSB (vent emissions not included). Diffuse fluxes of H2S were measured in Yellowstone for the first time and likely exceed 2.4??t d- 1 at HSB. Comparing estimates of the total estimated diffuse H2S emission to the amount of sulfur as SO42- in streams indicates ~ 50% of the original H2S in the gas emission is lost into shallow groundwater, precipitated as native sulfur, or vented through fumaroles. We estimate the heat output of HSB as ~ 140-370??MW using CO2 as a tracer for steam condensate, but not including the contribution from fumaroles and hydrothermal vents. Overall, the diffuse heat and volatile fluxes of HSB are as great as some active volcanoes, but they are a small fraction (1-3% for CO2, 2-8% for heat) of that estimated for the entire Yellowstone system.

Comparing chemolithoautotrophic subseafloor communities across geochemical gradients using meta-omics and RNA-SIP

NASA Astrophysics Data System (ADS)

Fortunato, C. S.; Huber, J. A.

2015-12-01

The chemolithoautotrophic microbial community of the rocky subseafloor potentially provides a large amount of organic carbon to the deep ocean, yet our understanding of the activity and metabolic complexity of subseafloor organisms remains poorly described. Past studies have shown that the taxonomic structure of subseafloor communities differs based on the geochemical signatures of individual vents. In this study, we expanded beyond phylogeny and used a combination of metagenomic, metatranscriptomic, and RNA-based stable isotope probing (RNA-SIP) analyses to identify the metabolic potential, expression patterns, and the active autotrophic players and genomic pathways present in venting fluids from Axial Seamount, an active submarine volcano off the coast of Oregon, USA. Low-temperature diffuse vent fluids from three hydrothermal vents, Marker 113, Marker 33, and Anemone, were filtered and preserved on the seafloor for metagenome and metatranscriptome analyses. Fluid for RNA-SIP was also collected and incubated shipboard with 13C-labeled sodium bicarbonate at 30ºC, 55ºC, and 80ºC for each vent. Taxonomically, Epsilonproteobacteria comprised a significant proportion of the community at all three vents, but each vent also had distinct groups that were abundant including SUP05 at Anemone and Methanococcus at Marker 113. Functionally, vents shared many metabolic processes including genes for denitrification, sulfur reduction and sulfur, hydrogen, and ammonium oxidation, which were present and expressed in similar abundance across all three vents. One metabolic difference between vents was the presence and expression of genes for methanogenesis, which were highly abundant and expressed at Marker 113, in lower abundance and expression at Marker 33, and not present at Anemone. RNA-SIP analysis is ongoing but initial results from Marker 113 revealed that at mesophilic, thermophilic, or hyperthemophilic temperatures, different genera and autotrophic metabolisms dominated. In addition, RNA-SIP showed that at 80ºC a different hyperthermophilic group dominated at each vent. Overall, this study demonstrates the metabolic and taxonomic diversity of the subseafloor and better characterizes the subseafloor chemolithoautotrophs and their role in biogeochemical cycling.

Microbial Community in the Hydrothermal System at Southern Mariana Trough

NASA Astrophysics Data System (ADS)

Kato, S.; Itahashi, S.; Kakegawa, T.; Utsumi, M.; Maruyama, A.; Ishibashi, J.; Marumo, K.; Urabe, T.; Yamagishi, A.

2004-12-01

There is unique ecosystem around deep-sea hydrothermal area. Living organisms are supported by chemical free energy provided by the hydrothermal water. The ecosystem is expected to be similar to those in early stage of life history on the earth, when photosynthetic organisms have not emerged. In this study, we have analyzed the microbial diversity in the hydrothermal area at southern Mariana trough. In the "Archaean Park Project" supported by special Coordination Fund, four holes were bored and cased by titanium pipes near hydrothermal vents in the southern Mariana trough in 2004. Hydrothermal fluids were collected from these cased holes and natural vents in this area. Microbial cells were collected by filtering the hydrothermal fluid in situ or in the mother sip. Filters were stored at -80C and used for DNA extraction. Chimneys at this area was also collected and stored at -80C. The filters and chimney samples were crushed and DNA was extracted. DNA samples were used for amplification of 16S rDNA fragments by PCR using archaea specific primers and universal primers. The PCR fragments were cloned and sequenced. These PCR clones of different samples will be compared. We will extend our knowledge about microbiological diversity at Southern Mariana trough to compare the results obtained at other area.

Looking for Larvae Above an Erupting Submarine Volcano, NW Rota-1, Mariana Arc

NASA Astrophysics Data System (ADS)

Beaulieu, S.; Hanson, M.; Tunnicliffe, V.; Chadwick, W. W., Jr.; Breuer, E. R.

2016-02-01

In 2009 the first marine protected areas for deep-sea hydrothermal vents in U.S. waters were established as part of the Volcanic Unit of the Marianas Trench Marine National Monument. In this region, hydrothermal vents are located along the Mariana Arc and back-arc spreading center. In particular hydrothermal vents are located near the summit of NW Rota-1, an active submarine volcano on the Mariana Arc which was erupting between 2003 and 2010 and ceased as of 2014. NW Rota-1 experienced a massive landslide in late 2009, decimating the habitat on the southern side of the volcano. This project looked at zooplankton tow samples taken from the water column above NW Rota-1 in 2010, searching for larvae which have the potential to recolonize the sea floor after such a major disturbance. Samples were sorted in entirety into coarse taxa, and then larvae were removed for DNA barcoding. Overall zooplankton composition was dominated by copepods, ostracods, and chaetognaths, the majority of which are pelagic organisms. Comparatively few larvae of benthic invertebrates were found, but shrimp, gastropod, barnacle, and polychaete larvae did appear in low numbers in the samples. Species-level identification obtained via genetic barcoding will allow for these larvae to be matched to species known to inhabit the benthic communities at NW Rota-1. Identified larvae will give insight into the organisms which can re-colonize the seafloor vent communities after a disturbance such as the 2009 landslide. Communities at hydrothermal vents at other submarine volcanoes in the Monument may act as sources for these larvae, but connectivity in this region of complex topography is unknown. As the microinvertebrate biodiversity in the Monument has yet to be fully characterized, our project also provides an opportunity to better describe both the zooplankton and benthic community composition in this area of the Monument.

Model for the Evolution of an Oceanic Core Complex and its Hydrothermal Vent on the Ultraslow-Spreading Mid Cayman Spreading Center

NASA Astrophysics Data System (ADS)

Harding, J.; Van Avendonk, H. J.; Hayman, N. W.; Grevemeyer, I.; Peirce, C.

2016-12-01

The Mid Cayman Spreading Center (MCSC) is an ultraslow-spreading center (15 mm yr-1 full rate) along the Caribbean-North American plate boundary. Despite the paradigm that ultraslow-spreading centers are amagmatic and cold, two hydrothermal vent fields have recently been discovered along the MCSC. The Beebe Vent Field is a black smoker in the northern axial deep, and the Von Damm Vent Field (VDVF) is a moderate-temperature, talc precipitating vent found atop an oceanic core complex (OCC). This OCC, "Mt. Dent", is a large (3 km high) massif that formed beneath a detachment fault, which exhumed lower crustal and upper mantle material. The CaySeis Experiment was conducted in April, 2015 in order to collect wide-angle refraction data of the MCSC crust and upper mantle. We modeled the across-axis crustal structure of Mt. Dent as well as the surrounding lithosphere using 2.5D P-wave tomography. Using this tomographic model, along with geochemistry, we propose a model for the formation and evolution of the OCC Mt. Dent and the VDVF. A detachment fault formed in a magma-poor environment due to a pulse of magmatism, producing a large gabbro body that was then exhumed and rotated into the OCC footwall. Once magmatism waned and the gabbroic body cooled, the OCC was faulted and fractured due to plate flexure and increased tectonic extensional stress in the naturally cold and thick lithosphere. These faults provide a permeable and deep network of hydrothermal pathways that mine deep lithospheric heat and expose gabbro and fresh mantle peridotite. This model is consistent with the basalt geochemistry, hydrothermal fluid geochemistry, and the distribution of brittle vs. ductile structures along the detachment shear zone. The VDVF is therefore a product of a pulse of magmatism in an overall melt-poor environment, conditions that may be found at other ultraslow-spreading ridges.

Metal interactions between the polychaete Branchipolynoe seepensis and the mussel Bathymodiolus azoricus from Mid-Atlantic-Ridge hydrothermal vent fields.

PubMed

Bebianno, Maria João; Cardoso, Cátia; Gomes, Tânia; Blasco, Julian; Santos, Ricardo Serrão; Colaço, Ana

2018-04-01

The vent blood-red commensal polynoid polychaete Branchipolynoe seepensis is commonly found in the pallial cavity of the vent mussel Bathymodiolus azoricus, the dominant bivalve species along the Mid-Atlantic-Ridge (MAR) and is known to be kleptoparasitic. Mussels were collected from three hydrothermal vent fields in the MAR: Menez Gwen (850 m depth, MG2, MG3 and MG4), Lucky Strike (1700 m depth, Montségur-MS and Eiffel Tower-ET) and Rainbow (2300 m depth). Polychaetes were absent in all Menez Gwen vent mussels, while the highest percentage was detected in mussels from Lucky Strike, where more than 70% of the mussels had at least one polychaete in their mantle cavity, followed by Rainbow with 33% of mussels with polychaetes. Total metal concentrations (Ag, Cd, Co, Cu, Fe, Mn, Ni and Zn) were determined in polychaetes whole body and in the mussel tissues (gills, digestive gland and mantle). To understand the possible metal interactions between symbiont and host, the activity of antioxidant defence (catalase (CAT), metallothioneins (MTs)), biotransformation enzymes (glutathione-s-transferases (GST)) activities and lipid peroxidation (LPO) were determined in polychaete whole soft tissues and in mussel tissues (gills, digestive gland and mantle). Metal concentrations in polychaetes and mussels tissues indicated that the accumulation patterns were species specific and also influenced by, and possibly dependent upon, the inter- and intra-variation of vent physico-chemistry between hydrothermal fields. Despite not detecting any strong correlations between metal and enzymes activities in polychaetes and mussels, when in presence of polychaetes, mussels presented less metal concentrations in the gills and digestive gland and lower activity of enzymatic biomarkers. This leads to infer that the polychaete plays a role on the detoxification process, and the interaction between the polychaete mussel association is probably an adaptation to metals concentrations at the vent sites. Copyright © 2018 Elsevier Ltd. All rights reserved.

Do larvae from deep-sea hydrothermal vents disperse in surface waters?

PubMed

Yahagi, Takuya; Kayama Watanabe, Hiromi; Kojima, Shigeaki; Kano, Yasunori

2017-06-01

Larval dispersal significantly contributes to the geographic distribution, population dynamics, and evolutionary processes of animals endemic to deep-sea hydrothermal vents. Little is known as to the extent that their larvae migrate vertically to shallower waters and experience stronger currents and richer food supplies. Here, we first provide evidence from early life-history traits and population genetics for the surface dispersal of a vent species. Planktotrophic larvae of a red blood limpet, Shinkailepas myojinensis (Gastropoda: Neritimorpha: Phenacolepadidae), were cultured to observe their swimming behavior and to evaluate the effects of temperature on survival and growth. In addition, the population structure was analyzed based on 1.2-kbp mitochondrial DNA sequences from 77 specimens that cover the geographic and bathymetric distributions of the species (northwest Pacific, 442-1,227 m in depth). Hatched larvae constantly swam upward at 16.6-44.2 mm/min depending on temperature. Vertical migration from hydrothermal vents to the surface, calculated to take ~4-43 d, is attainable given their lengthy survival time without feeding. Fed larvae best survived and grew at 25°C (followed by 20°C), which approximates the sea surface temperature in the geographic range of the species. Little or no growth was observed at the temperature of the vent habitat where adult limpets occur (≤15°C). Population genetic analyses showed no differentiation among localities that are <1,350 km apart. The larvae of S. myojinensis most likely migrate to the surface water, where high phytoplankton biomass and strong currents enable their growth and long distance dispersal over many months. Sea surface temperature may represent a critical factor in determining the geographic distribution of many vent endemic species with a planktotrophic early development, and in turn the faunal composition of individual vent sites and regions. © 2017 by the Ecological Society of America.

Differences in recovery between deep-sea hydrothermal vent and vent-proximate communities after a volcanic eruption

NASA Astrophysics Data System (ADS)

Gollner, Sabine; Govenar, Breea; Arbizu, Pedro Martinez; Mills, Susan; Le Bris, Nadine; Weinbauer, Markus; Shank, Timothy M.; Bright, Monika

2015-12-01

Deep-sea hydrothermal vents and the surrounding basalt seafloor are subject to major natural disturbance events such as volcanic eruptions. In the near future, anthropogenic disturbance in the form of deep-sea mining could also significantly affect the faunal communities of hydrothermal vents. In this study, we monitor and compare the recovery of insular, highly productive vent communities and vent-proximate basalt communities following a volcanic eruption that destroyed almost all existing communities at the East Pacific Rise, 9°50‧N in 2006. To study the recovery patterns of the benthic communities, we placed settlement substrates at vent sites and their proximate basalt areas and measured the prokaryotic abundance and compared the meio- and macrofaunal species richness and composition at one, two and four years after the eruption. In addition, we collected samples from the overlying water column with a pelagic pump, at one and two years after the volcanic eruption, to determine the abundance of potential meiofauna colonisers. One year after eruption, mean meio- and macrofaunal abundances were not significantly different from pre-eruption values in vent habitats (meio: 8-1838 ind. 64 cm-2 in 2006; 3-6246 ind. 64 cm-2 in 2001/02; macro: 95-1600 ind. 64 cm-2 in 2006; 205-4577 ind. 64 cm-2 in 2001/02) and on non-vent basalt habitats (meio: 10-1922 ind. 64 cm-2 in 2006; 8-328 ind. 64 cm-2 in 2003/04; macro: 14-3351 ind. 64 cm-2 in 2006; 2-63 ind. 64 cm-2 in 2003/04), but species recovery patterns differed between the two habitat types. In the vent habitat, the initial community recovery was relatively quick but incomplete four years after eruption, which may be due to the good dispersal capabilities of vent endemic macrofauna and vent endemic dirivultid copepods. At vents, 42% of the pre-eruption meio- and 39% of macrofaunal species had returned. In addition, some new species not evident prior to the eruption were found. At the tubeworm site Tica, a total of 26 meio- and 19 macrofaunal species were found in 2009, which contrasts with the 24 meio- and 29 macrofauna species detected at the site in 2001/02. In the basalt habitat, community recovery of meiofauna was slower with only 28% of the original 64 species present four years after eruption. The more limited dispersal capabilities of meiofauna basalt specialists such as nematodes or harpacticoid copepods probably caused this pattern. In contrast, 67% of the original 27 macrofaunal species had recolonized the basalt by 2009. Our results suggest that not only vent communities, but also species-rich communities of vent-proximate habitats require attention in conservation efforts.

Hydrothermal impacts on trace element and isotope ocean biogeochemistry.

PubMed

German, C R; Casciotti, K A; Dutay, J-C; Heimbürger, L E; Jenkins, W J; Measures, C I; Mills, R A; Obata, H; Schlitzer, R; Tagliabue, A; Turner, D R; Whitby, H

2016-11-28

Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2015 The Authors.

Hydrothermal impacts on trace element and isotope ocean biogeochemistry

PubMed Central

Dutay, J.-C.; Heimbürger, L. E.; Jenkins, W. J.; Measures, C. I.; Mills, R. A.; Obata, H.; Turner, D. R.; Whitby, H.

2016-01-01

Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035265

Hydrothermal venting along Earth's fastest spreading center: East Pacific Rise, 27.5°-32.3°

NASA Astrophysics Data System (ADS)

Baker, E. T.; Hey, R. N.; Lupton, J. E.; Resing, J. A.; Feely, R. A.; Gharib, J. J.; Massoth, G. J.; Sansone, F. J.; Kleinrock, M.; Martinez, F.; Naar, D. F.; Rodrigo, C.; Bohnenstiehl, D.; Pardee, D.

2002-07-01

During March/April 1998 we conducted detailed mapping and sampling of hydrothermal plumes along six segments of Earth's fasting spreading mid-ocean ridge, 27.5°-32.3°S on the East Pacific Rise. We compared the distribution and chemistry of hydrothermal plumes to geological indicators of long-term (spreading rate) and moderate-term (ridge inflation) variations in magmatic budget. In this large-offset, propagating rift setting, these geological indices span virtually the entire range found along fast spreading ridges worldwide. Hydrothermal plumes overlaid ~60% of the length of superfast (>130 km/Myr) spreading axis surveyed and defined at least 14 separate vent fields. We observed no plumes over the slower spreading propagating segments. Finer-scale variations in the magmatic budget also correlated with hydrothermal activity, as the location of the five most intense plumes corresponded to subsegment peaks in ridge inflation. Along the entire ridge crest, the more inflated a ridge location the more likely it was to be overlain by a hydrothermal plume. Plume chemistry mostly reflected discharge from mature vent fields apparently unperturbed by magmatic activity within the last few years. Plume samples with high volatile/metal ratios, generally indicating recent seafloor volcanism, were scarce. Along-axis trends in both volatile (3He; CH4; ΔpH, a proxy for CO2; and particulate S) and nonvolatile (Fe, Mn) species showed a first-order agreement with the trend of ridge inflation. Nevertheless, a broad correspondence between the concentration of volatile species in plumes and geological proxies of magma supply identifies a pervasive magmatic imprint on this superfast spreading group of ridge segments.

Continuing Investigations of the Relationship Between Fin Whales, Zooplankton Concentrations and Hydrothermal Venting on the Juan De Fuca Ridge

DTIC Science & Technology

2013-09-30

Fuca Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean...layer of increased acoustic backscatter near the 3 top of the hydrothermal plume (Thomson et al., 1991; Burd et al., 1992), leading to the...shallow species, which presumably migrate vertically between the upper ocean and the hydrothermal plume (Burd and Thomson, 1994, 1995). Our approach

Along-axis hydrothermal flow at the axis of slow spreading Mid-Ocean Ridges: Insights from numerical models of the Lucky Strike vent field (MAR)

NASA Astrophysics Data System (ADS)

Fontaine, Fabrice J.; Cannat, Mathilde; Escartin, Javier; Crawford, Wayne C.

2014-07-01

processes and efficiency of hydrothermal heat extraction along the axis of mid-ocean ridges are controlled by lithospheric thermal and permeability structures. Hydrothermal circulation models based on the structure of fast and intermediate spreading ridges predict that hydrothermal cell organization and vent site distribution are primarily controlled by the thermodynamics of high-temperature mid-ocean ridge hydrothermal fluids. Using recent constraints on shallow structure at the slow spreading Lucky Strike segment along the Mid-Atlantic Ridge, we present a physical model of hydrothermal cooling that incorporates the specificities of a magma-rich slow spreading environment. Using three-dimensional numerical models, we show that, in contrast to the aforementioned models, the subsurface flow at Lucky Strike is primarily controlled by across-axis permeability variations. Models with across-axis permeability gradients produce along-axis oriented hydrothermal cells and an alternating pattern of heat extraction highs and lows that match the distribution of microseismic clusters recorded at the Lucky Strike axial volcano. The flow is also influenced by temperature gradients at the base of the permeable hydrothermal domain. Although our models are based on the structure and seismicity of the Lucky Strike segment, across-axis permeability gradients are also likely to occur at faster spreading ridges and these results may also have important implications for the cooling of young crust at fast and intermediate spreading centers.

Abundant Hydrothermal Venting in the Southern Ocean Near 62°S/159°E on the Australian-Antarctic Ridge

NASA Astrophysics Data System (ADS)

Baker, E. T.; Hahm, D.; Rhee, T. S.; Park, S. H.; Lupton, J. E.; Walker, S. L.; Choi, H.

2014-12-01

Circum-Antarctic Ridges (CARs) comprise almost one-third of the global Mid-Ocean Ridge, yet remain terra incognita for hydrothermal activity and chemosynthetic ecosystems. The InterRidge Vents Database lists only 3 confirmed (visualized) and 35 inferred (plume evidence) active sites along the ~21,000 km of CARs. Here, we report on a multi-year effort to locate and characterize hydrothermal activity on two 1st-order segments of the Australian-Antarctic Ridge that are perhaps more isolated from other known vent fields than any other vent site on the Mid-Ocean Ridge. KR1 is a 300-km-long segment near 62°S/159°E, and KR2 a 90-km-long segment near 60°S/152.5°E. We used profiles collected by Miniature Autonomous Plume Recorders (MAPRs) on rock corers in March and December of 2011 to survey each segment, and an intensive CTD survey in Jan/Feb 2013 to pinpoint sites and sample plumes on KR1. Optical and oxidation-reduction potential (ORP, aka Eh) anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ~25 km. Forty profiles on KR1 identified 13 sites, some within a few km of each other. The densest site concentration on KR1 occurred along a relatively inflated, 90-km-long section near the segment center. CTD tows covered 20 km of the eastern, most inflated portion of this area, finding two 6-km-long zones centered near 158.6°E and 158.8°E with multiple plume anomalies. Three ORP anomalies within 50 m of the seafloor indicate precise venting locations. We call this area the Mujin "Misty Harbor" vent field. Vent frequency sharply decreases away from Mujin. 3He/heat ratios determined from 20 plume samples in the Mujin field were mostly <0.015 fM/J, indicative of chronic venting, but 3 samples, 0.021-0.034 fM/J, are ratios typical of a recent eruption. The spatial density of hydrothermal activity along KR1 and KR2 is similar to other intermediate-rate spreading ridges. We calculate the plume incidence (ph) along KR1 and KR2 as the mean of the fraction of MAPR casts detecting a plume in each 2nd-order segment. For all 6 segments, ph=0.37±0.25, consistent with the prediction of 0.33 from the global trend of ph for a spreading rate of 68 mm/yr.

Diversity of Total Bacterial Communities and Chemoautotrophic Populations in Sulfur-Rich Sediments of Shallow-Water Hydrothermal Vents off Kueishan Island, Taiwan.

PubMed

Wang, Li; Cheung, Man Kit; Liu, Rulong; Wong, Chong Kim; Kwan, Hoi Shan; Hwang, Jiang-Shiou

2017-04-01

Shallow-water hydrothermal vents (HTVs) are an ecologically important habitat with a geographic origin similar to that of deep-sea HTVs. Studies on shallow-water HTVs have not only facilitated understanding of the influences of vents on local ecosystems but also helped to extend the knowledge on deep-sea vents. In this study, the diversity of bacterial communities in the sediments of shallow-water HTVs off Kueishan Island, Taiwan, was investigated by examining the 16S ribosomal RNA gene as well as key functional genes involved in chemoautotrophic carbon fixation (aclB, cbbL and cbbM). In the vent area, Sulfurovum and Sulfurimonas of Epsilonproteobacteria appeared to dominate the benthic bacterial community. Results of aclB gene analysis also suggested involvement of these bacteria in carbon fixation using the reductive tricarboxylic acid (rTCA) cycle. Analysis of the cbbM gene showed that Alphaproteobacterial members such as the purple non-sulfur bacteria were the major chemoautotrophic bacteria involving in carbon fixation via the Calvin-Benson-Bassham (CBB) cycle. However, they only accounted for <2% of the total bacterial community in the vent area. These findings suggest that the rTCA cycle is the major chemoautotrophic carbon fixation pathway in sediments of the shallow-water HTVs off Kueishan Island.

Absolute Magnetization Distribution on Back-arc Spreading Axis Hosting Hydrothermal Vents; Insight from Shinkai 6500 Magnetic Survey

NASA Astrophysics Data System (ADS)

Fujii, M.; Okino, K.; Honsho, C.; Mochizuki, N.; Szitkar, F.; Dyment, J.

2013-12-01

Near-bottom magnetic profiling using submersible, deep-tow, Remotely Operated Vehicle (ROV) and Autonomous Underwater Vehicle (AUV) make possible to conduct high-resolution surveys and depict detailed magnetic features reflecting, for instance, the presence of fresh lavas or hydrothermal alteration, or geomagnetic paleo-intensity variations. We conducted near-bottom three component magnetic measurements onboard submersible Shinkai 6500 in the Southern Mariana Trough, where five active hydrothermal vent fields (Snail, Yamanaka, Archean, Pica, and Urashima sites) have been found in both on- and off-axis areas of the active back-arc spreading center, to detect signals from hydrothermally altered rock and to distinguish old and new submarine lava flows. Fourteen dives were carried out at an altitude of 1-40 m during the R/V Yokosuka YK10-10 and YK10-11 cruises in 2010. We carefully corrected the effect of the induced and permanent magnetizations of the submersible by applying the correction method for the shipboard three-component magnetometer measurement modified for deep-sea measurement, and subtracted the IGRF values from the corrected data to obtain geomagnetic vector anomalies along the dive tracks. We then calculated the synthetic magnetic vector field produced by seafloor, assumed to be uniformly magnetized, using three dimensional forward modeling. Finally, values of the absolute magnetizations were estimated by using a linear transfer function in the Fourier domain from the observed and synthetic magnetic anomalies. The distribution of estimated absolute magnetization generally shows low values around the five hydrothermal vent sites. This result is consistent with the equivalent magnetization distribution obtained from previous AUV survey data. The areas of low magnetization are also consistent with hydrothermal deposits identified in video records. These results suggest that low magnetic signals are due to hydrothermal alteration zones where host rocks are demagnetized by hydrothermal circulation. The low magnetization zones around the off-axis vent sites are about ten times wider than those surrounding the on-axis sites, possibly reflecting the longer duration of hydrothermal circulation at these sites. Another interesting result is that the absolute magnetization shows extremely high intensities (>80 A/m) at the neo volcanic zones (NVZ) and relatively low intensities (<10 A/m) two to five kilometers away from the NVZ. These variations are quite consistent with those of the Natural Remanent Magnetization measured on basalt samples, suggesting that the low-temperature oxidation of host rock due to the reaction with seawater has completed within a few kilometers distance from the spreading axis. We conclude that the magnetization of the uppermost oceanic crust decreases with age due to the combination of the both hydrothermal rapid alteration and the low-temperature gradual alteration processes.

Geology and lithogeochemistry of hydrothermal mudstones from the upper block near the Duck Pond volcanogenic massive sulfide (VMS) deposit, Newfoundland, Canada: evidence for low-temperature venting into oxygenated mid-Cambrian seawater

NASA Astrophysics Data System (ADS)

Piercey, Stephen J.; Squires, Gerry; Brace, Terry

2018-02-01

Pyrite- and pyrrhotite-rich mudstones are spatially associated with Cambrian ( 512-509 Ma) volcanogenic massive sulfide (VMS) deposits throughout the Tally Pond group, central Newfoundland, Canada. At the Duck Pond mine, sulfide-rich mudstones are hosted within a weakly mineralized upper block that structurally overlies the deposit but is older ( 513 versus 509 Ma). The mudstones are laminated, 10-30-cm thick, and pyrite- and pyrrhotite-rich and occur along pillow lava selvages, or in between pillow lavas, rhyolite flows, and volcaniclastic rocks. The mudstones are laterally extensive and proximal to the mudstone host rocks are hydrothermally altered to epidote-quartz-chlorite (basalt host) and sericite-quartz (rhyolite host). Lithogeochemical data for the sulfide-rich mudstones reflect the varying contributions of elements from sedimentary detritus, hydrothermal discharge, and hydrogenous scavenging from middle Cambrian seawater. The mudstones have minor detrital element abundances and significant hydrothermal element enrichments (i.e., elevated Fe2O3, S, Pb, Zn, Cu, and Ba concentrations, high Fe/Al ratios). The hydrothermal mudstones are also enriched in oxyanions (i.e., P2O5, U, V, Cr, Ni, Co, and Hg), interpreted to have been enriched via oxidative scavenging from seawater by Fe-oxide/oxyhydroxide particles. The mudstones also have REE-Y signatures similar to modern oxygenated seawater with high Y/Ho and negative Ce anomalies (Ce/Ce* = 0.40-0.86; average = 0.58), which correlate with adsorbed oxyanion concentrations. The low Eu/Eu* (1.02-1.86; average = 1.22) in the mudstones suggest that they were deposited from low-temperature (< 250 °C), Fe-rich hydrothermal fluids that likely formed a buoyant plume into an oxygenated water column. The REE-Y-oxyanion signatures suggest that the particles within the hydrothermal plume had sufficient residence time to scavenge oxyanions from seawater and inherit a middle Cambrian seawater signature. The predominant seawater REE-Y-oxyanion signature in the Duck Pond upper block sulfide-rich mudstones suggests that they are distal hydrothermal sedimentary rocks that could have formed up to 10 km from their original vent sources. Correspondingly, to utilize hydrothermal mudstones as vectors to mineralization in the Tally Pond belt, and similar belts globally, it is critical to identify vent-proximal samples that have hydrothermal signatures (i.e., high Fe/Al, base metals, Ba, S), with subdued seawater and adsorption signatures (i.e., chondritic Y/Ho, low P2O5, Ni, U, Co, Cr, V, and Hg), indicating minimal residence time in the water column and deposition proximal to the vent.

Evolution of the Mothra Hydrothermal Field, Endeavour Segment of the Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Glickson, D.; Kelley, D. S.; Delaney, J.

2005-12-01

The Mothra Hydrothermal Field (MHF) is a 600 m long, high-temperature hydrothermal field. It is located 2.7 km south of the Main Endeavour Field at the southern end of the central Endeavour Segment. Mothra is the most areally extensive field along the Endeavour Segment, composed of six active sulfide clusters that are 40-200 m apart. Each cluster contains rare black smokers (venting up to 319°C), numerous diffusely venting chimneys, and abundant extinct chimneys and sulfide talus. From north to south, these clusters include Cauldron, Twin Peaks, Faulty Towers, Crab Basin, Cuchalainn, and Stonehenge. As part of the Endeavour Integrated Study Site (ISS), the MHF is a site of intensive interdisciplinary studies focused on linkages among geology, geochemistry, fluid chemistry, seismology, and microbiology. Axial valley geology at MHF is structurally complex, consisting of lightly fissured flows that abut the walls and surround a core of extensively fissured, collapsed terrain. Fissure abundance and distribution indicates that tectonism has been the dominant process controlling growth of the axial graben. Past magmatic activity is shown by the 200 m long chain of collapse basins between Crab Basin and Stonehenge, which may have held at least ~7500 m3 of lava. Assuming a flow thickness of 0.5 m, this amount of lava could cover over half the valley floor during a single volcanic event. At a local scale, MHF clusters vary in size, activity, and underlying geology. They range in size from 400-1600 m2 and consist of isolated chimneys and/or coalesced cockscomb arrays atop ramps of sulfide talus. In the northern part of the field, Cauldron, Twin Peaks, Faulty Towers, and Crab Basin are located near the western valley wall, bounded by basalt talus and a combination of collapsed sheet flows, intermixed lobate and sulfide, disrupted terrain, and isolated pillow ridges. The southern clusters, Cuchalainn and Stonehenge, are associated with collapse basins in the central valley and bounded by extensive lobate flows and disrupted terrain. At all clusters, active chimneys stand within meters of extinct chimneys, suggesting that flow in the shallow subsurface is both complex and transient. 1-2 m high mounds of sulfide talus and broken chimneys indicate that focused flow has been concentrated at the clusters for long periods, while extinct sulfide deposits between clusters and in collapse basins demonstrate that flow conduits have been rerouted and/or clogged by mineral precipitation. Two subsurface processes are responsible for hydrothermal venting at the clusters: tapping of magmatic heat near the lava drainbacks and tectonic movement along the steeply dipping, inward-facing normal faults at the western wall boundary. The interplay between these processes and fluid flow is synthesized in an evolutionary model of hydrothermal development at Mothra.

Effects of pH and Redox Gradients on Prebiotic Organic Synthesis and the Generation of Free Energy in Simulated Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Barge, L. M.; Flores, E.; Abedian, Y.; Maltais, T.; Cameron, R.; Hermis, N.; Chin, K.; Russell, M. J.; Baum, M. M.

2017-07-01

Hydrothermal minerals in alkaline vents can promote phosphorus and organic concentration, redox reactions driven by catalytic metal sulfides, and the ambient pH and redox gradients can affect the synthesis of organics.

Marine Subsurface Microbial Communities Across a Hydrothermal Gradient in Okinawa Trough Sediments

NASA Astrophysics Data System (ADS)

Brandt, L. D.; Hser Wah Saw, J.; Ettema, T.; House, C. H.

2015-12-01

IODP Expedition 331 to the Okinawa backarc basin provided an opportunity to study the microbial stratigraphy within the sediments surrounding a hydrothermal vent. The Okinawa backarc basin is a sedimented region of the seafloor located on a continental margin, and also hosts a hydrothermal network within the subsurface. Site C0014 within the Iheya North hydrothermal field is located 450 m east of the active vent and has a surface temperature of 5°C with no evidence of hydrothermal alteration within the top 10 meters below sea floor (mbsf). Temperature increases with depth at an estimated rate of 3°C/m and transitions from non-hydrothermal margin sediments to a hydrothermally altered regime below 10 mbsf. In this study, we utilized deep 16S rRNA sequencing of DNA from IODP Expedition 331 Site C0014 sediment horizons in order to assess diversity throughout the sediment column as well as determine the potential limits of the biosphere. Analysis of the amplicon data shows a shift over 15 mbsf from a heterogeneous community of cosmopolitan marine subsurface taxa toward an archaeal-dominated community in the deepest horizons of the predicted biosphere. Notably, the phylum Chloroflexi represents a substantial taxon through most horizons, where it appears to be replaced below 10 mbsf by punctuations of thermophilic and methanotrophic Archaea and Miscellaneous Crenarchaeotic Group abundances. DNA from the aforementioned transition horizons was further analyzed using metagenomic sequencing. Preliminary taxonomic analysis of the metagenomic data agrees well with amplicon data in capturing the shift in relative abundance of Archaea increasing with depth. Additionally, reverse gyrase, a gene found exclusively in hyperthermophilic microorganisms, was recovered only in the metagenome of the deepest horizon. A BLAST search of this protein sequence against the GenBank non-redudnant protein database produced top hits with reverse gyrase from Thermococcus and Pyrococcus, which are known thermophiles. Up until now, thermophiles and hyperthermophiles have been studied in cultured hydrothermal vent fluid samples, or have been identified from 16S rRNA taxonomic analyses. These recovered genes provide direct evidence for a pervasive subsurface hyperthermophilic biosphere in off-axis hydrothermal sediments.

Helium and carbon gas geochemistry of pore fluids from the sediment-rich hydrothermal system in Escanaba Trough

USGS Publications Warehouse

Ishibashi, J.-I.; Sato, M.; Sano, Y.; Wakita, H.; Gamo, T.; Shanks, Wayne C.

2002-01-01

Ocean Drilling Program (ODP) Leg 169, which was conducted in 1996 provided an opportunity to study the gas geochemistry in the deeper part of the sediment-rich hydrothermal system in Escanaba Trough. Gas void samples obtained from the core liner were analyzed and their results were compared with analytical data of vent fluid samples collected by a submersible dive program in 1988. The gas geochemistry of the pore fluids consisted mostly of a hydrothermal component and was basically the same as that of the vent fluids. The He isotope ratios (R/RA = 5.6-6.6) indicated a significant mantle He contribution and the C isotopic compositions of the hydrocarbons [??13C(CH4) = -43???, ??13C(C2H6) = -20???] were characterized as a thermogenic origin caused by hydrothermal activity. On the other hand, the pore fluids in sedimentary layers away from the hydrothermal fields showed profiles which reflected lateral migration of the hydrothermal hydrocarbons and abundant biogenic CH4. Helium and C isotope systematics were shown to represent a hydrothermal component and useful as indicators for their distribution beneath the seafloor. Similarities in He and hydrocarbon signatures to that of the Escanaba Trough hydrothermal system were found in some terrestrial natural gases, which suggested that seafloor hydrothermal activity in sediment-rich environments would be one of the possible petroleum hydrocarbon generation scenarios in unconventional geological settings. ?? 2002 Elsevier Science Ltd. All rights reserved.

The use of 210Pb/Pb as a Tracer of Chemosynthetic and Photosynthetic Organic Carbon in Hydrothermal Vent Particles

NASA Astrophysics Data System (ADS)

Kadko, D.

2004-12-01

Jack Dymond pioneered the use of sediment traps to understand the chemistry and flux of material emanating from submarine hydrothermal vents. For example, in one paper Roth and Dymond (1989) used the ratio of Corg/CCaCO3 between traps to determine the fraction of chemosynthetically derived organic carbon (OC) in collected material. Knowledge of the relative proportion of chemosynthetic and photosynthetic OC is critical to mass balance calculations of hydrothermal OC inputs/exports and can also be determined from the 210Pb/Pb ratio measured in the sediment traps and suspended particles. The 210Pb/Pb ratio of particles in the ridge environment is diagnostic of the source and path of the particles. At the Endeavour Ridge, particles emanating directly from vents have a ratio close to that of the vent fluids and basalt ( ˜0.5 dpm/μ g) from where they are derived, and subsequently scavenge additional 210Pb as they disperse. It is therefore reasonable to assume that particles with a 210Pb/Pb ratio of 0.5 are "fresh" and any OC associated with them must be chemosynthetic in origin. This ratio is much smaller than that of typical (non-vent) seawater (>3 dpm/μ g) and thus particles in the upper water column (or distant from vents) will have a high 210Pb/Pb ratio and contain OC predominantly from photosynthetic production. The 210Pb/Pb ratio of Endeavour particles increase markedly from <0.70 at a vent orifice, to 1.22 within the buoyant plume ( ˜20 ma vent), to 1.4 downstream (~2 km) within the neutrally-buoyant plume at 2100 m depth. These plume particles are distinguished from those above the plume (at 1700 m with 210Pb/Pb = 3.2 dpm/μ g) by lower 210Pb/Pb ratios but much higher 210Pb content. The high Pb content attests to a hydrothermal component of the plume particles. Therefore, the 210Pb/Pb ratio can be used to define two conservative endmembers for a particle population: those derived from the vents will have a ratio of 0.5 (with 100% chemosynthetic OC) and those derived from the surface ocean will have a ratio of 3.2 (from the 1700m trap, with 100% photosynthetic OC). With these endmembers, a linear relationship between the % chemosynthetic OC and 210Pb/Pb is: % OCchemo = -37 x (210Pb/Pb) + 118.45 The flux of OCchemo can be compared to the downward flux of photosynthetic OC from the surface ocean by another method utilizing 210Pb as a proxy of OC flux in the Pacific which was introduced in Moore and Dymond, (1988).

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 autonomously taking gas-tight fluid samples. If used with HOV or ROV, it will reduce basket space occupation and ICL communication cables compared to traditional single-bottle gas-tight samplers. This time serial gas-tight fluid sampler will be further developed into a 36 bottle system for remote operation with seafloor cabled observatory.

Influence of magmatic volatiles on boron isotope compositions in vent fluids from the Eastern Manus Basin, Papua New Guinea

NASA Astrophysics Data System (ADS)

Wilckens, F. K.; Kasemann, S.; Bach, W.; Reeves, E. P.; Meixner, A.; Seewald, J.

2016-12-01

In this study we present boron (B), lithium (Li) and strontium (Sr) concentrations and isotopic composition of submarine hydrothermal fluids collected in 2006 and 2011 from PACMANUS, DESMOS and SuSu Knolls vent fields located in the Eastern Manus Basin [1,2]. Hydrothermal vent fluids within the Eastern Manus Basin range from high-temperature black smoker fluids to low-temperature diffuse fluids and acid-sulfate fluids. In general, the different fluid types show variable water-rock ratios during water-rock interaction and different inputs of magmatic volatiles. End-member black smoker fluids, which have in general high temperatures (mostly higher than 280°C) and pH values higher than 2 (measured at 25°C) are characterized by low δ7Li values (3.9 to 5.9‰) and 87Sr/86Sr ratios (0.704 to 0.705) similar to the values for island arc basalts. These results suggest low water-rock ratios during hydrothermal circulation. B concentrations and isotopic compositions in these fluids range from 1.0 to 2.6μM and 13 to 20‰, respectively. These data match with other vent fluids from island arc settings in the Western Pacific and plot in a B versus δ11B diagram on a two-component mixing line between seawater and island arc basalts [3]. Sr and Li isotopic composition of white smoker and acid-sulfate fluids overlap generally with the isotopic ratios for the black smoker fluids. However, in some fluids Sr isotope ratios are up to 0.709 near seawater composition suggesting higher water-rock ratios during water-rock interaction. B concentrations and isotope ratios in the white smoker and acid-sulfate fluids range from 0.6 to 2.2μM and 9 to 16‰, respectively which are lower compared with the values of black smoker fluids. In addition, these fluids do not fit on the mixing line between seawater and island arc basalt, and define another mixing trend in a B versus δ11B diagram. To explain this contradictory trend, a third mixing endmember is required that shifts B concentrations and δ11B to lower values. A possible mixing endmember is B volatized from magmatic gases. This endmember seems to be reasonable because it only influences B, whereas Li and Sr stay unaffected. [1] Reeves et al. (2011) GCA 75, 1088-1123 [2] Seewald et al. (2015) GCA 163, 178-199 [3] Yamaoka et al. (2015) CG 392, 9-18

Pito Seamount revisited: the discovery and mapping of new black smoker vents

NASA Astrophysics Data System (ADS)

Cheadle, M. J.; John, B. E.; German, C. R.; Gee, J. S.; Coogan, L. A.; Gillis, K. M.; Swapp, S.

2017-12-01

In February 2017, the RV Atlantis PMaG (PaleoMagnetism and Gabbro) cruise re-visited a black smoker site originally discovered 24 years ago on Pito Seamount, by the submersible Nautile during the French Pito expedition (1993). Pito Seamount (111.639oW, 23.333oS) marks the northern tip of the propagating East Pacific Rise, bounding the east side of the Easter Microplate. There the seafloor rises to 2250mbsl and has a 900m wide, 50m deep axial valley, which hosts at least two separate fields of active hydrothermal vents. AUV Sentry mapping of the summit of Pito seamount (0.5-1m resolution) highlights over 50 active and inactive chimneys amid recent basaltic sheet flows, pillow mounds and ponded lava. The vents occur in two fields/sub-fields; the first covers an area of 800 x 200m, and lies parallel to the ridge axis, along incipient faults forming on the northeastern flank of the axial valley. The second field occurs in a 250m diameter area in the centre of the axial valley. Jason II dive 961 visited, sampled, measured vent orifice temperatures, and acquired 4k video of the chimneys, and re-discovered the active (Magnificent Village) vent first found by Nautile, in the now named Nautile vent field, together with five additional active hydrothermal vents (Jason, Medea, Sentry, Abe and Scotty's Castle). The Magnificent Village, the largest active vent, is 25m tall and has multiple active spires in three main groups surrounding a hollow amphitheater. Measured vent orifice temperatures ranged from 338oC (Magnificent Village) to 370oC (Jason). The vents host a fauna of alvinellid worms, bythograidid crabs, alvincardid shrimps, phymorhynchus gastropods, Corallimorphid anenomes and bathymodiolid mussels, but no vestimentiferan worms. Brisingid brittle stars colonize inactive chimneys.

Time-series analysis of two hydrothermal plumes at 9°50'N East Pacific Rise reveals distinct, heterogeneous bacterial populations.

PubMed

Sylvan, J B; Pyenson, B C; Rouxel, O; German, C R; Edwards, K J

2012-03-01

We deployed sediment traps adjacent to two active hydrothermal vents at 9°50'N on the East Pacific Rise (EPR) to assess the variability in bacterial community structure associated with plume particles on the timescale of weeks to months, to determine whether an endemic population of plume microbes exists, and to establish ecological relationships between bacterial populations and vent chemistry. Automated rRNA intergenic spacer analysis (ARISA) indicated that there are separate communities at the two different vents and temporal community variations between each vent. Correlation analysis between chemistry and microbiology indicated that shifts in the coarse particulate (>1 mm) Fe/(Fe+Mn+Al), Cu, V, Ca, Al, (232) Th, and Ti as well as fine-grained particulate (<1 mm) Fe/(Fe+Mn+Al), Fe, Ca, and Co are reflected in shifts in microbial populations. 16S rRNA clone libraries from each trap at three time points revealed a high percentage of Epsilonproteobacteria clones and hyperthermophilic Aquificae. There is a shift toward the end of the experiment to more Gammaproteobacteria and Alphaproteobacteria, many of whom likely participate in Fe and S cycling. The particle-attached plume environment is genetically distinct from the surrounding seawater. While work to date in hydrothermal environments has focused on determining the microbial communities on hydrothermal chimneys and the basaltic lavas that form the surrounding seafloor, little comparable data exist on the plume environment that physically and chemically connects them. By employing sediment traps for a time-series approach to sampling, we show that bacterial community composition on plume particles changes on timescales much shorter than previously known. © 2012 Blackwell Publishing Ltd.

GeoChip-based analysis of metabolic diversity of microbial communities at the Juan de Fuca Ridge hydrothermal vent

PubMed Central

Wang, Fengping; Zhou, Huaiyang; Meng, Jun; Peng, Xiaotong; Jiang, Lijing; Sun, Ping; Zhang, Chuanlun; Van Nostrand, Joy D.; Deng, Ye; He, Zhili; Wu, Liyou; Zhou, Jizhong; Xiao, Xiang

2009-01-01

Deep-sea hydrothermal vents are one of the most unique and fascinating ecosystems on Earth. Although phylogenetic diversity of vent communities has been extensively examined, their physiological diversity is poorly understood. In this study, a GeoChip-based, high-throughput metagenomics technology revealed dramatic differences in microbial metabolic functions in a newly grown protochimney (inner section, Proto-I; outer section, Proto-O) and the outer section of a mature chimney (4143-1) at the Juan de Fuca Ridge. Very limited numbers of functional genes were detected in Proto-I (113 genes), whereas much higher numbers of genes were detected in Proto-O (504 genes) and 4143-1 (5,414 genes). Microbial functional genes/populations in Proto-O and Proto-I were substantially different (around 1% common genes), suggesting a rapid change in the microbial community composition during the growth of the chimney. Previously retrieved cbbL and cbbM genes involved in the Calvin Benson Bassham (CBB) cycle from deep-sea hydrothermal vents were predominant in Proto-O and 4143-1, whereas photosynthetic green-like cbbL genes were the major components in Proto-I. In addition, genes involved in methanogenesis, aerobic and anaerobic methane oxidation (e.g., ANME1 and ANME2), nitrification, denitrification, sulfate reduction, degradation of complex carbon substrates, and metal resistance were also detected. Clone libraries supported the GeoChip results but were less effective than the microarray in delineating microbial populations of low biomass. Overall, these results suggest that the hydrothermal microbial communities are metabolically and physiologically highly diverse, and the communities appear to be undergoing rapid dynamic succession and adaptation in response to the steep temperature and chemical gradients across the chimney. PMID:19273854

Reactivity landscape of pyruvate under simulated hydrothermal vent conditions

PubMed Central

Novikov, Yehor; Copley, Shelley D.

2013-01-01

Pyruvate is an important “hub” metabolite that is a precursor for amino acids, sugars, cofactors, and lipids in extant metabolic networks. Pyruvate has been produced under simulated hydrothermal vent conditions from alkyl thiols and carbon monoxide in the presence of transition metal sulfides at 250 °C [Cody GD et al. (2000) Science 289(5483):1337–1340], so it is plausible that pyruvate was formed in hydrothermal systems on the early earth. We report here that pyruvate reacts readily in the presence of transition metal sulfide minerals under simulated hydrothermal vent fluids at more moderate temperatures (25–110 °C) that are more conducive to survival of biogenic molecules. We found that pyruvate partitions among five reaction pathways at rates that depend upon the nature of the mineral present; the concentrations of H2S, H2, and NH4Cl; and the temperature. In most cases, high yields of one or two primary products are found due to preferential acceleration of certain pathways. Reactions observed include reduction of ketones to alcohols and aldol condensation, both reactions that are common in extant metabolic networks. We also observed reductive amination to form alanine and reduction to form propionic acid. Amino acids and fatty acids formed by analogous processes may have been important components of a protometabolic network that allowed the emergence of life. PMID:23872841

First insights into macro- and meiofaunal colonisation patterns on paired wood/slate substrata at Atlantic deep-sea hydrothermal vents

NASA Astrophysics Data System (ADS)

Cuvelier, Daphne; Beesau, Julie; Ivanenko, Viatcheslav N.; Zeppilli, Daniela; Sarradin, Pierre-Marie; Sarrazin, Jozée

2014-05-01

In 2006, paired wood and slate panels, each equipped with a temperature probe, were deployed on three different localities on and around the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) within close proximity of visible hydrothermal activity. Recovery of these panels took place in 2008. For this two-year deployment period, the composition of colonising organisms (both macro-and meiofauna) was assessed, along with image analyses of the deployment sites in 2006 and 2008. Very few significant differences in colonisation between organic (wood) and inorganic (slate) panels were revealed. Rather, the locality of deployment and the local environmental conditions and hydrothermal activity were found to influence taxonomic composition. Variability in microhabitat conditions and biological interactions were hypothesised to interact jointly in shaping new faunal communities on the colonisation substrata.

First hydrothermal active vent discovered on the Galapagos Microplate

NASA Astrophysics Data System (ADS)

Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

2011-12-01

The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

Investigating the Relationship Between Fin and Blue Whale Locations, Zooplankton Concentrations and Hydrothermal Venting on the Juan de Fuca Ridge

DTIC Science & Technology

2008-01-01

such correlations in terms of the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean. OBJECTIVES We are...in a 100-m-thick layer of increased acoustic backscatter near the top of the hydrothermal plume at 1.9 km depth (Thomson et al., 1991, Burd et al...zooplankton migrate vertically between the upper ocean and the hydrothermal plume (Burd & Thomson, 1994). This interpretation is consistent with a

Investigating the Relationship Between Fin and Blue Whale Locations, Zooplankton Concentrations and Hydrothermal Venting on the Juan de Fuca Ridge

DTIC Science & Technology

2009-09-30

Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean. OBJECTIVES...to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean. 15. SUBJECT TERMS 16. SECURITY... hydrothermal plume at 1.9 km depth [Burd et al., 1992; Thomson et al., 1991a], leading to the inference that the zooplankton were taking advantage of the

Continuing Investigations of the Relationship between Fin Whales, Zooplankton Concentrations and Hydrothermal Venting on the Juan de Fuca Ridge

DTIC Science & Technology

2012-09-30

Fuca Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean...a layer of increased acoustic backscatter near the top of the hydrothermal plume (Thomson et al., 1991; Burd et al., 1992), leading to the inference...shallow species which presumably migrate vertically between the upper ocean and the hydrothermal plume (Burd and Thomson, 1994, 1995). Our approach is

Liquid Carbon Dioxide Venting at the Champagne Hydrothermal Site, NW Eifuku Volcano, Mariana Arc

NASA Astrophysics Data System (ADS)

Lupton, J.; Lilley, M.; Butterfield, D.; Evans, L.; Embley, R.; Olson, E.; Proskurowski, G.; Resing, J.; Roe, K.; Greene, R.; Lebon, G.

2004-12-01

In March/April 2004, submersible dives with the remotely-operated vehicle ROPOS discovered an unusual CO2-rich hydrothermal system near the summit of NW Eifuku, a submarine volcano located at 21.49° N, 144.04° E in the northern Mariana Arc. Although several sites of hydrothermal discharge were located on NW Eifuku, the most intense venting was found at 1600-m depth at the Champagne site, slightly west of the volcano summit. The Champagne site was found to be discharging two distinct fluids into the ocean: a) several small white chimneys were emitting milky 103° C gas-rich hydrothermal fluid with at least millimolar levels of H2S and b) cold (< 4° C) droplets coated with a milky skin were rising slowly from the sediment. These droplets were later determined to consist mainly of liquid CO2, with H2S as a probable secondary component. The droplets were sticky, and did not tend to coalesce into larger droplets, even though they adhered to the ROV like clumps of grapes. The film coating the droplets was assumed to be CO2 hydrate (or clathrate) which is known to form whenever liquid CO2 contacts water under these P,T conditions. Samples of the 103° C hydrothermal fluids were collected in special gas-tight titanium sampling bottles that were able to withstand the high internal pressures created by the dissolved gases. The Champagne hydrothermal fluids contained a surprising 2.3 moles/kg of CO2, an order of magnitude higher than any CO2 values previously reported for submarine hydrothermal fluids. The overall gas composition was 87% CO2, < 0.1% CH4, < 2 ppm H2, 0.012 mM/kg 4He, with the remaining 13% (322 mM/kg) assumed to be sulfur gases (H2S, SO2, etc.). (Additional analyses planned will confirm the speciation of this sulfur gas component). The helium had R/RA = 7.3, typical of subduction zone systems (R = 3He/4He and RA = Rair). Isotopic analysis of the CO2 yielded δ 13C = -1.75 ‰ , much heavier than the -6.0 ‰ typical for carbon in MOR vent fluids. The C/3He ratio was ~2.2 x 1010, an order of magnitude higher than the average value of 2 x 109 found in MOR vent fluids. The δ 13C and C/3He values suggest a substantial contribution to the carbon from subducted carbonates rather than mantle carbon. The Champagne site is only the second locality where liquid CO2 has been observed venting into the deep sea (the other reported location is in the Okinawa Trough, see Sakai et al., 1990). Because of the presence of liquid CO2 in proximity to hydrothermal organisms, the Champagne site may prove to be a valuable natural laboratory for studying the effects of high CO2 concentrations on marine ecosystems.

Electrochemistry of Prebiotic Early Earth Hydrothermal Chimney Systems

NASA Astrophysics Data System (ADS)

Hermis, N.; Barge, L. M.; Chin, K. B.; LeBlanc, G.; Cameron, R.

2017-12-01

Hydrothermal chimneys are self-organizing chemical garden precipitates generated from geochemical disequilibria within sea-vent environments, and have been proposed as a possible setting for the emergence of life because they contain mineral catalysts and transect ambient pH / Eh / chemical gradients [1]. We simulated the growth of hydrothermal chimneys in early Earth vent systems by using different hydrothermal simulants such as sodium sulfide (optionally doped with organic molecules) which were injected into an early Earth ocean simulant containing dissolved ferrous iron, nickel, and bicarbonate [2]. Chimneys on the early Earth would have constituted flow-through reactors, likely containing Fe/Ni-sulfide catalysts that could have driven proto-metabolic electrochemical reactions. The electrochemical activity of the chimney system was characterized non-invasively by placing electrodes at different locations across the chimney wall and in the ocean to analyze the bulk properties of surface charge potential in the chimney / ocean / hydrothermal fluid system. We performed in-situ characterization of the chimney using electrochemical impedance spectroscopy (EIS) which allowed us to observe the changes in physio-chemical behavior of the system through electrical spectra of capacitance and impedance over a wide range of frequencies during the metal sulfide chimney growth. The electrochemical properties of hydrothermal chimneys in natural systems persist due to the disequilibria maintained between the ocean and hydrothermal fluid. When the injection in our experiment (analogous to fluid flow in a vent) stopped, we observed a corresponding decline in open circuit voltage across the chimney wall, though the impedance of the precipitate remained lor. Further work is needed to characterize the electrochemistry of simulated chimney systems by controlling response factors such as electrode geometry and environmental conditions, in order to simulate electrochemical reactions that may have occurred in similar systems on the early Earth. [1] Russell, MJ et al. 2014. Astrobiology,14, 4, 308-343. [2] Barge, LM et al. (2015) Journal of Visualized Experiments, 105, DOI: 10.3791/53015.

Role of a unique population of lithotrophic, Fe-oxidizing bacteria in forming microbial Fe-mats at the Loihi Seamount.

NASA Astrophysics Data System (ADS)

Emerson, D.; Rentz, J. A.; Moyer, C. L.

2005-12-01

The Loihi Seamount, located 30 km SE of the island of Hawai'i, is among the most active volcanos on Earth. The summit, at a depth of 1100m, includes a 250m deep caldera (Pele's Pit) formed by an eruption in 1996. The summit, and especially Pele's Pit, are the site of extensive low to intermediate temperature (10° to 65°C) hydrothermal venting, emanating both from diffuse fissures and orifices that have substantial flow rates. The vent fluid is characterized by a low sulfide content, high CO2 concentrations and Fe(II) amounts in the 10s to 100s of μM. Associated with all vents are extensive deposits of iron oxyhydroxides that typically have 107 to 108 bacterial cells/cc associated with them. The morphology of the Fe-oxides are indicative of biological origins. We have isolated microaerophilic, obligately lithotrophic Fe-oxidizing bacteria from Loihi and describe here `Mariprofundus ferroxydans' a unique bacterium that forms a filamentous iron oxide mineral. `M. ferroxydans' is the first cultured representative of a novel division of the Proteobacteria, known previously only from clones from different hydrothermal vent sites. Molecular evidence from Loihi mats based on clone libraries and terminal restriction length polymorphism (T-RFLP) analysis of 16S rRNA genes indicate that this lineage of Fe-oxidizing organisms are common inhabitants at Loihi. We speculate that this organism and its relatives form the basis of an active microbial mat community that owe their existence to the inherent gradients of Fe(II) and O2 that exist at the Loihi vents. In a geological context this is interesting because the Loihi summit and caldera are in an O2-minima zone; O2 concentrations in the bulk seawater are around 0.5 mg/l. In effect, Loihi could serve as a proxy for the late Archaean and early Proterozoic periods when the Earth's atmosphere went from reducing to oxidizing, and it is speculated that abundant Fe(II) in the Earth's oceans served as a major sink for O2 production preventing its accumulation in the atmosphere. Better understanding of extant conditions at Loihi might help us frame questions concerning the role of lithotrophic iron-oxidizing bacteria in the rusty ocean of the late Archaean Earth.

Event Detection for Hydrothermal Plumes: A case study at Grotto Vent

NASA Astrophysics Data System (ADS)

Bemis, K. G.; Ozer, S.; Xu, G.; Rona, P. A.; Silver, D.

2012-12-01

Evidence is mounting that geologic events such as volcanic eruptions (and intrusions) and earthquakes (near and far) influence the flow rates and temperatures of hydrothermal systems. Connecting such suppositions to observations of hydrothermal output is challenging, but new ongoing time series have the potential to capture such events. This study explores using activity detection, a technique modified from computer vision, to identify pre-defined events within an extended time series recorded by COVIS (Cabled Observatory Vent Imaging Sonar) and applies it to a time series, with gaps, from Sept 2010 to the present; available measurements include plume orientation, plume rise rate, and diffuse flow area at the NEPTUNE Canada Observatory at Grotto Vent, Main Endeavour Field, Juan de Fuca Ridge. Activity detection is the process of finding a pattern (activity) in a data set containing many different types of patterns. Among many approaches proposed to model and detect activities, we have chosen a graph-based technique, Petri Nets, as they do not require training data to model the activity. They use the domain expert's knowledge to build the activity as a combination of feature states and their transitions (actions). Starting from a conceptual model of how hydrothermal plumes respond to daily tides, we have developed a Petri Net based detection algorithm that identifies deviations from the specified response. Initially we assumed that the orientation of the plume would change smoothly and symmetrically in a consistent daily pattern. However, results indicate that the rate of directional changes varies. The present Petri Net detects unusually large and rapid changes in direction or amount of bending; however inspection of Figure 1 suggests that many of the events detected may be artifacts resulting from gaps in the data or from the large temporal spacing. Still, considerable complexity overlies the "normal" tidal response pattern (the data has a dominant frequency of ~12.9 hours). We are in the process of defining several events of particular scientific interest: 1) transient behavioral changes associated with atmospheric storms, earthquakes or volcanic intrusions or eruptions, 2) mutual interaction of neighboring plumes on each other's behavior, and 3) rapid shifts in plume direction that indicate the presence of unusual currents or changes in currents. We will query the existing data to see if these relationships are ever observed as well as testing our understanding of the "normal" pattern of response to tidal currents.Figure 1. Arrows indicate plume orientation at a given time (time axis in days after 9/29/10) and stars indicate times when orientation changes rapidly.

Spatial and Temporal Variability in Microbial Communities from Pre- and Post-Eruption Microbial Mats Collected from Loihi Seamount, Hawaii: An Update

NASA Astrophysics Data System (ADS)

Moyer, C. L.; Davis, R. E.; Curtis, A. C.; Rassa, A. C.

2007-12-01

Loihi Seamount is an active submarine volcano that marks the southernmost extent of the Hawaiian hotspot. Loihi rises over 3000 meters from the seafloor and summits nearly 1000 meters below sea level. Hydrothermal activity was discovered at Loihi in 1987, yielding diffuse vent effluent (Tmax 37°C) with associated high CO2 and Fe(II) concentrations and luxuriant microbial mats located near the summit of the volcano. Loihi erupted most recently in 1996 forming a new 300 meter deep caldera (Pele's Pit) with hydrothermal venting up to 200°C. Pele's Pit has cooled and now contains multiple hydrothermal vents with hydrothermal fluids ranging from 8-58°C with concentrations of Fe(II) remaining between 50 and 750 μM. Community fingerprints from over 75 microbial mat samples have now been collected from Loihi Seamount from 1993 to 2006, with temperatures ranging from ambient (~4°C) up to nearly ~200°C. These samples were analyzed using Pearson product-moment coupled with UPGMA cluster analysis of terminal- restriction fragment length polymorphisms (T-RFLP) coupled with traditional clone library and sequence analysis to identify the primary populations within each community. These mat samples form two distinct community clusters (Loihi Cluster Group 1 and Group 2) representing a combined 90% of all mat samples collected. Loihi Cluster Group 1 is by far the largest group (n = 45) and contains the most mat samples collected over time. Group 1 is dominated by phylotypes closely related to the recently described zeta- Proteobacteria that includes the type strain Mariprofundus ferrooxydans, an obligately lithotrophic, Fe-oxidizing bacterium. Loihi Cluster Group 2 is comprised of only post-eruption communities (n = 18) that generally contain greater diversity (in terms of richness) than Group 1 communities. Group 2 communities are primarily dominated by a unique array of phylotypes belonging to the Nitrospira division and by the class epsilon- Proteobacteria, including many putative sulphur-oxidizing bacteria. Interestingly, we have recently witnessed a shift away from the Group 2 communities back to the Group 1 communities. Only 2 of 11 microbial mat samples collected in 2004 exhibited the Group 2 community structure. All 10 of the mat samples collected in 2006 from multiple locations exhibited the Group 1 community structure, indicating a reduced overall diversity within Pele's Pit and a return to the microbial mats being dominated by Fe-oxidizing bacteria.

Evidence of a modern deep water magmatic hydrothermal system in the Canary Basin (eastern central Atlantic Ocean)

NASA Astrophysics Data System (ADS)

Medialdea, T.; Somoza, L.; González, F. J.; Vázquez, J. T.; de Ignacio, C.; Sumino, H.; Sánchez-Guillamón, O.; Orihashi, Y.; León, R.; Palomino, D.

2017-08-01

New seismic profiles, bathymetric data, and sediment-rock sampling document for the first time the discovery of hydrothermal vent complexes and volcanic cones at 4800-5200 m depth related to recent volcanic and intrusive activity in an unexplored area of the Canary Basin (Eastern Atlantic Ocean, 500 km west of the Canary Islands). A complex of sill intrusions is imaged on seismic profiles showing saucer-shaped, parallel, or inclined geometries. Three main types of structures are related to these intrusions. Type I consists of cone-shaped depressions developed above inclined sills interpreted as hydrothermal vents. Type II is the most abundant and is represented by isolated or clustered hydrothermal domes bounded by faults rooted at the tips of saucer-shaped sills. Domes are interpreted as seabed expressions of reservoirs of CH4 and CO2-rich fluids formed by degassing and contact metamorphism of organic-rich sediments around sill intrusions. Type III are hydrothermal-volcanic complexes originated above stratified or branched inclined sills connected by a chimney to the seabed volcanic edifice. Parallel sills sourced from the magmatic chimney formed also domes surrounding the volcanic cones. Core and dredges revealed that these volcanoes, which must be among the deepest in the world, are constituted by OIB-type, basanites with an outer ring of blue-green hydrothermal Al-rich smectite muds. Magmatic activity is dated, based on lava samples, at 0.78 ± 0.05 and 1.61 ± 0.09 Ma (K/Ar methods) and on tephra layers within cores at 25-237 ky. The Subvent hydrothermal-volcanic complex constitutes the first modern system reported in deep water oceanic basins related to intraplate hotspot activity.