Note: This page contains sample records for the topic hydrothermal vent site from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Discovery of new hydrothermal vent sites in Bransfield Strait, Antarctica  

NASA Astrophysics Data System (ADS)

We carried out a search for hydrothermal vents in the Central Basin of Bransfield Strait, Antarctica. The ZAPS (zero angle photon spectrometer) chemical sensor and instrument package (Oregon State University), OFOS (ocean-floor observation system) camera sled and TVG (TV-grab) (GEOMAR) were used to explore the water column and underlying seafloor. These operations were supplemented with a series of dredges. Hydrothermal plumes over Hook Ridge at the eastern end of the basin are confined to the E ridge crest and SE flank. The plumes are complex and sometimes contain two turbidity maxima one widespread feature centered at 1150 m and a smaller, more localized but broad maximum at 600-800 m. We traced the source of the shallower plume to a sunken crater near the ridge crest using sensors on the ZAPS instrument package. Subsequently two TV-grabs from the crater brought back hot, soupy sediment (42-49°C) overlain by hard, siliceous crusts and underlain by a thick layer of volcanic ash. We also recovered chimney fragments whose texture and mineralogy indicate venting temperatures in excess of 250°C. Native sulfur and Fe-sulfides occur in fractures and porous layers in sediment from throughout the area. Pore water data from the crater site are consistent with venting into a thin sediment layer and indicate phase separation of fluids beneath Hook Ridge. The source of the deeper plumes at Hook Ridge has yet to be located. We also explored a series of three parallel volcanic ridges west of Hook Ridge called Three Sisters. We detected water column anomalies indicative of venting with the ZAPS package and recovered hydrothermal barites and sulfides from Middle Sister. We spent considerable time photographing Middle Sister and Hook Ridge but did not identify classic vent fauna at either location. We either missed small areas with our photography or typical MOR vent fauna are absent at these sites.

Klinkhammer, G. P.; Chin, C. S.; Keller, R. A.; Dählmann, A.; Sahling, H.; Sarthou, G.; Petersen, S.; Smith, F.; Wilson, C.

2001-12-01

2

Quantifying diffuse and discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field  

NASA Astrophysics Data System (ADS)

The relative heat carried by diffuse versus discrete venting of hydrothermal fluids at mid-ocean ridges is poorly constrained and likely varies among vent sites. Estimates of the proportion of heat carried by diffuse flow range from 0% to 100% of the total axial heat flux. Here, we present an approach that integrates imagery, video, and temperature measurements to accurately estimate this partitioning at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperatures, photographic mosaics of the vent site, and video sequences of fluid flow were acquired during the Bathyluck'09 cruise (Fall, 2009) and the Momarsat'10 cruise (Summer, 2010) to the Lucky Strike hydrothermal field by the ROV Victor6000 aboard the French research vessel the "Pourquoi Pas"? (IFREMER, France). We use two optical methods to calculate the velocities of imaged hydrothermal fluids: (1) for diffuse venting, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time, and (2) for discrete jets, Particle Image Velocimetry tracks eddies by cross-correlation of pixel intensities between subsequent images. To circumvent video blurring associated with rapid velocities at vent orifices, exit velocities at discrete vents are calculated from the best fit of the observed velocity field to a model of a steady state turbulent plume where we vary the model vent radius and fluid exit velocity. Our results yield vertical velocities of diffuse effluent between 0.9 cm s-1 and 11.1 cm s-1 for fluid temperatures between 3°C and 33.5°C above that of ambient seawater, and exit velocities of discrete jets between 22 cm s-1 and 119 cm s-1 for fluid temperatures between 200°C and 301°C above ambient seawater. Using the calculated fluid velocities, temperature measurements, and photo mosaics of the actively venting areas, we calculate a heat flux due to diffuse venting from thin fractures of 3.15 ± 2.22 MW, discrete venting of 1.07 ± 0.66 MW, and, by incorporating previous estimates of diffuse heat flux density from Tour Eiffel, diffuse flux from the main sulfide mound of ˜15.6 MW. We estimate that the total integrated heat flux from the Tour Eiffel site is 19.82 ± 2.88 MW and that the ratio of diffuse to discrete heat flux is ˜18. We discuss the implication of these results for the characterization of different vent sites within Lucky Strike and in the context of a compilation of all available measurements of the ratio of diffuse to discrete heat flux.

Mittelstaedt, Eric; EscartíN, Javier; Gracias, Nuno; Olive, Jean-Arthur; Barreyre, Thibaut; Davaille, Anne; Cannat, Mathilde; Garcia, Rafael

2012-04-01

3

Bacteria at Hydrothermal Vents  

NSDL National Science Digital Library

This website provides information on thermophiles living in deep-sea vents, including their importance in biotechnology and extraterrestrial life research. The site also contains images of thermophiles at varying scales and a link to the "Hot Topics" main page including numerous links to further information on hydrothermal vents and research conducted in deep-sea environments.

Discover, Expeditions T.; Woods Hole Oceanographic Institution, National S.

4

Diffuse versus discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field  

NASA Astrophysics Data System (ADS)

Two styles of fluid flow at the seafloor are widely recognized: (1) localized outflows of high temperature (>300°C) fluids, often black or grey color in color (“black smokers”) and (2) diffuse, lower temperature (<100°C), fluids typically transparent and which escape through fractures, porous rock, and sediment. The partitioning of heat flux between these two types of hydrothermal venting is debated and estimates of the proportion of heat carried by diffuse flow at ridge axes range from 20% to 90% of the total axial heat flux. Here, we attempt to improve estimates of this partitioning by carefully characterizing the heat fluxes carried by diffuse and discrete flows at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperature and video data were acquired during the recent Bathyluck’09 cruise to the Lucky Strike hydrothermal field (September, 2009) by Victor aboard “Pourquoi Pas?” (IFREMER, France). Temperature measurements were made of fluid exiting discrete vents, of diffuse effluents immediately above the seafloor, and of vertical temperature gradients within discrete hydrothermal plumes. Video data allow us to calculate the fluid velocity field associated with these outflows: for diffuse fluids, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time; for individual hydrothermal plumes, Particle Image Velocimetry tracks eddies by cross-correlation of pixels intensities between subsequent images. Diffuse fluids exhibit temperatures of 8-60°C and fluid velocities of ~1-10 cm s-1. Discrete outflows at 204-300°C have velocities of ~1-2 m s-1. Combined fluid flow velocities, temperature measurements, and full image mosaics of the actively venting areas are used to estimate heat flux of both individual discrete vents and diffuse outflow. The total integrated heat flux and the partitioning between diffuse and discrete venting at Tour Eiffel, and its implications for the nature of hydrothermal activity across the Lucky Strike site are discussed along with the implications for crustal permeability, associated ecosystems, and mid-ocean ridge processes.

Mittelstaedt, E. L.; Escartin, J.; Gracias, N.; Olive, J. L.; Barreyre, T.; Davaille, A. B.; Cannat, M.

2010-12-01

5

Dive and Discover's Deeper Discovery: Hydrothermal Vents  

NSDL National Science Digital Library

Dive and Discover is an interactive distance learning web site designed to immerse you in the excitement of discovery and exploration of the deep seafloor. On this particular website, Dive and Discover takes you on a deeper discovery of hydrothermal vents. This site features an introduction to hydrothermal vent systems, including vent basics, vents around the world, chemistry, boiling points, interactive diagrams, videos, a quiz, and links to selected Dive and Discover hydrothermal vent-related seafloor expeditions. This web page also provides links to other Deeper Discovery topics, Dive and Discover seafloor expeditions, a teacher's page, and further Dive and Discover information.

2010-04-12

6

Modeling Hydrothermal Vents on Europa  

NASA Astrophysics Data System (ADS)

Simulations of potential hydrothermal vents at Europa's ocean floor are presented. The effects of differing initial rock composition and temperature are explored with respect to mineral formation and vent fluid composition.

Gavin, P.; Vance, S.

2012-03-01

7

Liquid Carbon Dioxide Venting at the Champagne Hydrothermal Site, NW Eifuku Volcano, Mariana Arc  

NASA Astrophysics Data System (ADS)

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 ? 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 ? 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.

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

8

Microbial Utilization of Naturally Occurring Hydrocarbons at the Guaymas Basin Hydrothermal Vent Site  

PubMed Central

The Guaymas Basin (Gulf of California; depth, 2,000 m) is a site of hydrothermal activity in which petroliferous material is formed by thermal alteration of deposited planktonic and terrestrial organic matter. We investigated certain components of these naturally occurring hydrocarbons as potential carbon sources for a specific microflora at these deep-sea vent sites. Respiratory conversion of [1-14C]hexadecane and [1(4,5,8)-14C]naphthalene to 14CO2 was observed at 4°C and 25°C, and some was observed at 55°C, but none was observed at 80°C. Bacterial isolates were capable of growing on both substrates as the sole carbon source. All isolates were aerobic and mesophilic with respect to growth on hydrocarbons but also grew at low temperatures (4 to 5°C). These results correlate well with previous geochemical analyses, indicating microbial hydrocarbon degradation, and show that at least some of the thermally produced hydrocarbons at Guaymas Basin are significant carbon sources to vent microbiota.

Bazylinski, Dennis A.; Wirsen, Carl O.; Jannasch, Holger W.

1989-01-01

9

The Discovery of Marine Hydrothermal Vents  

NSDL National Science Digital Library

As part of OceanLink, a website dedicated to ocean education, this site gives an overview of the discovery, geology and ecology of marine hydrothermal vents. The site also provides a menu of links to access other OceanLink pages for further ocean-related information.

Oceanlink

10

Hydrothermal Vents: Thar She Blows!  

NSDL National Science Digital Library

In this lesson students will discover how the proximity of hot magma to cold ocean water creates new rocky structures around hydrothermal vents. During this activity, students will demonstrate an understanding of how the processes that result in the formation of hydrothermal vents create new ocean floor and how the transfer of energy effects solids and liquids. This hands-on activity uses online data resources and includes: focus questions, learning objectives, teaching time, audio/visual materials needed, background information, learning procedures, evaluations, extensions, as well as resources and student handouts.

11

Mystery of the Megaplume: Hydrothermal Vent Chemistry  

NSDL National Science Digital Library

In this lesson, students will investigate hydrothermal vents to see how the chemistry of the water they emit provides clues to the location of the vents. They should be able to describe hydrothermal vents and characterize vent plumes in terms of physical and chemical properties; describe data gathering operations in which a towed instrument package ("tow-yo") measures conductivity, temperature, and depth; and interpret temperature anomaly data to recognize a plume emanating from a hydrothermal vent.

12

Hydrothermal sediments as a potential record of seawater Nd isotope compositions: The Rainbow vent site (36°14?N, Mid-Atlantic Ridge)  

Microsoft Academic Search

Geochemical compositions and Sr and Nd isotopes were measured in two cores collected ?2 and 5 km from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge. Overall, the cores record enrichments in Fe and other metals from hydrothermal fallout, but sequential dissolution of the sediments allows discrimination between a leach phase (easily leachable) and a residue phase (refractory). The

Valérie Chavagnac; Martin R. Palmer; J. Andrew Milton; Darryl R. H. Green; Christopher R. German

2006-01-01

13

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)

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 ?g/l at 200-700 m above the seafloor; TSM concentrations > 60 ?g/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 ?g/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 ?g 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 ?g/g, respectively. The complementary behavior of dissolved Mn and particulate trace metals provides a useful framework for studying broad aspects of hydrothermal plume processes.

Trocine, Robert P.; Trefry, John H.

1988-04-01

14

We're in Hot Water Now: Hydrothermal Vents  

NSDL National Science Digital Library

In this lesson students will access a link to another site to learn about the processes that drive geysers, which are roughly analogous to hydrothermal vents. They will then examine photographs of some hydrothermal vents, discuss the reasons they occur, and learn about some uniquely adapted animals that live near the vents. They will conclude by creating aquarium exhibits showcasing some of these animals and their special adaptations.

15

Hydrothermal Plume Mapping Along the Hotspot-affected Galapagos Spreading Center Finds High-Temperature Vent Sites are Anomalously Scarce  

NASA Astrophysics Data System (ADS)

Systematic searches for hydrothermal activity along midocean ridges (MORs) demonstrate that the spatial density of hydrothermal activity is a robust linear function of spreading rate. This trend argues that the availability of mantle heat is the first order control on the distribution of seafloor vent fields. However, some crustal thermal models predict that the thicker, hotter, more ductile crust associated with hotspots substantially reduces convective hydrothermal cooling, explaining observations of axial magma chambers (AMC) at shallower depths than found on normal MORs. In Dec-Jan 2006 we tested this hypothesis by mapping hydrothermal plumes overlying the hotspot-affected Galapagos Spreading Center (GSC) from 95°-89.6°W, using a dual-pass, side-scan deep tow with an array of plume sensors spanning 50- 250 m above bottom. The western GSC near 91°-92.5°W has axial-high morphology, shallow and quasi-continuous AMC, and thick (8 km) crust, changing to a transitional morphology, deeper and more discontinuous AMC, and normal (6 km) crust from 93° to 95°W. The eastern GSC, 90.5°- 89.6°W is also an axial high and presumably has crustal characteristics similar to the western GSC at 91°-92.5°W. We identified hydrothermal plumes by anomalies in light backscattering (NTU) from a vertical array of MAPR sensors along the tow line, plus redox potential (Eh) measured continuously in-situ on the tow body at a nominal elevation of 100 m. Many plumes were subsequently confirmed by CTD tows and sampling. Only three areas of extensive and intense plumes were observed: 90.52°-90.63°W, 91.78°- 91.96°W, and 94°-94.1°W. Maximum plume rise at the latter two sites exceeded 200 m, indicative of high-temperature venting that was confirmed by camera tows. Some 25 other NTU and Eh anomalies were detected along ~1000 km of trackline, but none were >5 km in length. The primary result of our survey is that hydrothermal plumes were scarce for a ridge spreading at ~60 mm/yr. Total plume incidence (ph), the fraction of ridge crest overlain by plumes, was 0.076, about a third of that expected for a normal ridge section of similar spreading rate. While the overall low ph is consistent with the hypothesis that the Galapagos hotspot has stifled convective cooling, the distribution of plumes points to a more complex relationship between geology and venting. Where the crust is thickest and the AMC shallowest (91°-92.5°W) ph = 0.124; where the crust thins and the AMC deepens (92.5°-95°W) ph = 0.065. One extensive vent field was active in each of these areas. The eastern GSC section is morphologically similar to the 91°-92.5°W section but has a lower ph = 0.067 and no evidence of high-temperature vents. The GSC joins MORs over the Iceland (Reykjanes Ridge) and Amsterdam/St Paul (SEIR) hotspots as locations of significantly reduced high-temperature venting. The importance of low-temperature, diffuse venting as a cooling agent on hotspot-affected ridges remains unresolved.

Baker, E. T.; Resing, J. A.; Walker, S. L.; Lebon, G. T.; Nakamura, K.; Haymon, R. M.; White, S. M.; MacDonald, K. C.

2006-12-01

16

Hydrothermal Plume Mapping Along the Hotspot-affected Galapagos Spreading Center Finds High-Temperature Vent Sites are Anomalously Scarce  

Microsoft Academic Search

Systematic searches for hydrothermal activity along midocean ridges (MORs) demonstrate that the spatial density of hydrothermal activity is a robust linear function of spreading rate. This trend argues that the availability of mantle heat is the first order control on the distribution of seafloor vent fields. However, some crustal thermal models predict that the thicker, hotter, more ductile crust associated

E. T. Baker; J. A. Resing; S. L. Walker; G. T. Lebon; K. Nakamura; R. M. Haymon; S. M. White; K. C. MacDonald

2006-01-01

17

Microorganisms as food resources at deep-sea hydrothermal vents  

Microsoft Academic Search

We used stable isotopes of carbon and nitrogen to examine the diversity of microbial populations consumed as foods at deep-sea hydrothermal vents. Invertebrate consumers at Gorda and Juan de Fuca Ridge vent sites had variable carbon isotope compositions, implying the use of more than one microbial food resource. 6'C values for consumer invertebrates at Gorda ranged between - 13.2% (polynoid

CINDY LEE VAN DOVER; BRIAN FRY

1994-01-01

18

Modelling of hydrothermal fluid circulation in a heterogeneous medium: Application to the Rainbow Vent site (Mid-Atlantic-Ridge, 36°14N)  

NASA Astrophysics Data System (ADS)

Hydrothermal activity at the axis of mid-ocean ridges is a key driver for energy and matter transfer from the interior of the Earth to the ocean floor. At mid-ocean ridges, seawater penetrates through the permeable young crust, warms at depth and exchanges chemicals with the surrounding rocks. This hot fluid focuses and flows upwards, then is expelled from the crust at hydrothermal vent sites in the form of black or white smokers completed by diffusive emissions. We developed a new numerical tool in the Cast3M software framework to model such hydrothermal circulations. Thermodynamic properties of one-phase pure water were calculated from the IAPWS formulation. This new numerical tool was validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also gave results in good agreement with already published simulations. We used this new numerical tool to construct a geometric and physical model configuration of the Rainbow Vent site at 36°14'N on the Mid-Atlantic Ridge. In this presentation, several configurations will be discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modelled with hydrothermal circulation in a homogeneous-permeability porous medium. We will show that these high values require the presence of a fault or a preferential pathway right below the venting site. We will propose and discuss a 2-D one-path model that allows us to simulate both high temperatures and high mass fluxes. This modelling of the hydrothermal circulation at the Rainbow site constitutes a first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field.

Perez, F.; Mügler, C.; Jean-Baptiste, P.; Charlou, J. L.

2012-04-01

19

Candy Chemosynthesis: Biochemistry of Hydrothermal Vents  

NSDL National Science Digital Library

In this activity, students will differentiate between requirements for life in extreme environments such as hydrothermal vents and other environments and will use soft candy as a model to create a visual image of chemicals involved in autotrophic nutrition. As they review the biochemistry of hydrothermal vents, they will discover what chemicals are used by autotrophs in extreme environments in the deep ocean and how these chemicals differ from those used by terrestrial autotrophs. They will also study a diagram showing how a hydrothermal vent (black smoker) acquires the elements and compounds that deep-sea autotrophs require.

20

Do organisms living around hydrothermal vent sites contain specific metallothioneins? The case of the genus Bathymodiolus (Bivalvia, Mytilidae)  

Microsoft Academic Search

The unusual characteristics of the hydrothermal vent environment (high pressure and metal concentrations, low pH, etc.) leads us to wonder how species living in this particular biotope have adjusted to these severe living conditions. To investigate the consequences of high metal concentrations, filter-feeding organisms are commonly used in ecotoxicological studies. Metallothioneins (MTs) are proteins conserved throughout the animal kingdom and

Yann Hardivillier; Vincent Leignel; Françoise Denis; Gabriel Uguen; Richard Cosson; Marc Laulier

2004-01-01

21

Spatial variation of metal bioaccumulation in the hydrothermal vent mussel Bathymodiolus azoricus  

Microsoft Academic Search

The variability of the bioaccumulation of metals (Ag, Cd, Cu, Fe, Mn, Zn) was extensively studied in the mussel Bathymodiolus azoricus from five hydrothermal vent sites inside three main vent fields of increasing depth along the Mid Atlantic Ridge: Menez-Gwen, Lucky-Strike and Rainbow. Metal bioaccumulation varied greatly between vent fields and even between sites inside a vent field with B.

Richard P. Cosson; Éric Thiébaut; Maryse Castrec-Rouelle

22

Vertebrate nutrition in a deep-sea hydrothermal vent ecosystem: Fatty acid and stable isotope evidence  

Microsoft Academic Search

The hydrothermal vent zoarcid fish Thermarces cerberus is a top predator that inhabits deep-sea hydrothermal vents on the East Pacific Rise (EPR). Bacterial chemoautotrophy at these sites supports abundant animal communities. Paradoxically, these chemoautotrophic bacteria are not known to produce polyunsaturated fatty acids (PUFA), dietary nutrients essential for all marine vertebrates. To understand how T. cerberus successfully exploits the vent

D. W. Pond; A. E. Fallick; C. J. Stevens; D. J. Morrison; D. R. Dixon

2008-01-01

23

Fine-Scale Three-Dimensional Mapping of a Deep-Sea Hydrothermal Vent Site Using the Jason ROV System  

Microsoft Academic Search

Using precise navigation, a computer-controlled remotely operated vehicle, and a variety of optical and acoustic imaging sensors, we created the most precise three-dimensional renderings ever made of an active hydrothermal vent field at a depth of 2400 meters on the deep sea floor. Data products included electronic and film photographs as well as three-dimensional sonar scans. We used these to

Dana R. Yoerger; Deborah S. Kelley; John R. Delaney

2000-01-01

24

Fluid Flow and Sound Generation at Hydrothermal Vent Fields.  

National Technical Information Service (NTIS)

Several experiments in this thesis examine methods to measure and monitor fluid flow from hydrothermal vent fields. Simultaneous velocity temperature, and conductivity data were collected in the convective flow emanating from a hydrothermal vent field loc...

S. A. Little

1988-01-01

25

Bacterial Diets of Primary Consumers at Hydrothermal Vents  

NASA Astrophysics Data System (ADS)

Chemical energy produced by mixing hydrothermal fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal vents is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the vent-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in hydrothermal vent communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among hydrothermal vent primary consumers and to track the flow of energy in hydrothermal vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal vent site on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets of these four hydrothermal vent gastropods may reflect microhabitat conditions where these species typically occur or where they were located at the time of the collection. Results from this work provide insights to the "bottom-up" regulation of primary consumers and tracking chemical fluxes through biological communities at hydrothermal vents.

Govenar, B.; Shank, T. M.

2008-12-01

26

Microbiology of deep-sea hydrothermal vents  

Microsoft Academic Search

Before the discovery of deep-sea hydrothermal vents in 1977, the deep sea was perceived as a cold, dark, high-pressure and nutrient-poor environment inhabited by psychrophilic, oligotrophic and barotolerant-to-barophilic microbial communities. By contrast, deep-sea-vent areas are warm-to-hot and inhabited by animal communities whose density may reach 50 kg m?2. Invertebrates living in these warm biotopes are in endosymbiotic relationships with autotrophic

Daniel Prieur

1997-01-01

27

Sonar images hydrothermal vents in seafloor observatory  

NASA Astrophysics Data System (ADS)

Hydrothermal plumes venting from black smokers and diffuse flow discharging from the surrounding area of the seafloor are important as agents of transfer of heat, chemicals, and biological material from the crust into the ocean in quantitatively significant amounts [Elderfield and Schultz, 1996]. An unprecedented time series of three-dimensional (3-D) volume images of plumes rising tens of meters from black smoker vents and of concurrent 2-D maps of diffuse flow discharging from surrounding areas of the seafloor illuminates the turbulent behavior of hydrothermal fluid transfer into the ocean (see Figure 1).

Rona, Peter; Light, Russ

2011-05-01

28

Ecology of deep-sea hydrothermal vent communities: A review  

Microsoft Academic Search

The present article reviews studies of the past 15 years of active and inactive hydrothermal vents. The focus of the discussion is on the ecology of the biological communities inhabiting hydrothermal vents. These communities exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. The authors attempt to relate the biology of hydrothermal vent systems

Richard A. Lutz; Michael J. Kennish

1993-01-01

29

Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming  

Microsoft Academic Search

Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C\\/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized

M. A. Kaplinski; P. Morgan

1993-01-01

30

Evidence for Hydrothermal Vents as "Biogeobatteries" (Invited)  

NASA Astrophysics Data System (ADS)

Hydrothermal vents are unique systems that play an important role in oceanic biogeochemical cycles. As chemically reduced hydrothermal fluid mixes with cold oxic seawater, minerals precipitate out of solution resulting in chimney structures composed largely of metal sulfides and anhydrite. Pyrite, which is a natural semi-conductor, is the primary sulfide mineral, but other minerals within chimneys are also conductive (e.g. chalcopyrite, wurtzite, and some iron oxides). Sulfide chimneys are also known to host an extensive endolithic microbial community. Accordingly, submarine hydrothermal systems appear to be examples of biogeobatteries, wherein conductive mineral assemblages span naturally occuring redox gradients and enable anaerobic microbes to access oxygen as an oxidant via extracellular electron transfer (or EET). To test this hypothesis, we ran a series of electrochemical laboratory experiments in which pyrite was used as an anode (in a vessel flushed with hydrothermal-like fluid). When placed in continuity with a carbon fiber cathode, pyrite was found to accept and conduct electrons from both abiotic and biological processes (microbial EET). Specifically, electrical current increased 4-fold (5 nA/m2 to 20 nA/m2) in response to inoculation with a slurry prepared from a hydrothermal vent sample. Inspection of the pyrite anode with SEM revealed ubiquitous coverage by microbes. DNA was extracted from the anodes and the inoculum, and was subjected to pyrosequencing to examine prokaryotic diversity. These data suggest that key microbial phylotypes were enriched upon the pyrite, implicating them in EET. In addition, we deployed an in situ experiment based on microbial fuel cell architecture with a graphite anode inserted into a vent wall coupled to a carbon fiber cathode outside the vent. We observed current production over the course of one year, implying microbial EET in situ. Via pyrosequencing, we observed that the microbial community on the anode was significantly enriched in gammaproteobacteria (with respect to the community on an inert substrate deployed in the same vent, which was dominated by epsilonproteobacteria). The observation of electrical current and the enrichment of distinct microbial communities in both laboratory and in situ experiments provide evidence that hydrothermal vents enable microbes capable of EET to access molecular oxygen in the surrounding seawater as an oxidant. This geochemical and microbial phenomenon may influence the chemistry and mineralogy of vent systems, resulting in localized variations in pH that can influence metal mobilization on a global scale.

Nielsen, M. E.; Girguis, P. R.

2010-12-01

31

High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization  

NASA Astrophysics Data System (ADS)

Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the Kolumbo submarine crater today.

Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

2006-12-01

32

SUCCESSIONAL MECHANISM VARIES ALONG A GRADIENT IN HYDROTHERMAL FLUID FLUX AT DEEP-SEA VENTS  

Microsoft Academic Search

Invertebrate communities inhabiting deep-sea hydrothermal vents undergo substantial succession on time scales of months. Manipulative field experiments assessed the relative roles of environmental state and biotic interactions in determining temporal succession along a spatial gradient in vent fluid flux at three vent sites near 9 8509 N on the East Pacific Rise (2500 m water depth). Species colonization patterns on

Lauren S. Mullineaux; Charles H. Peterson; Fiorenza Micheli; Susan W. Mills

2003-01-01

33

Hydrothermal Vent System Unlike Any Seen Before Found in Atlantic  

NSDL National Science Digital Library

This web page is a press release form the University of Washington relating that a team of scientists led by Deborah Kelly, on Dec. 4 2000, discovered a new hydrothermal vent system that has been named "The Lost City". This unique hydrothermal field is located on an undersea mountain in the Atlantic Ocean and contains towers reaching 180 feet above the sea floor composed of silica and carbonate minerals. This is more than 100 feet taller than the average hydrothermal vents previously observed which are composed of iron and sulfur-based minerals. The web site has high-resolution images of these unique underwater features and has links to the investigators that participated in the discovery.

Hines, Sandra; Meredith, Dennis; Clark, Cindy; Dybas, Cheryl

2010-01-28

34

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

National Technical Information Service (NTIS)

Ecological processes at deep-sea hydrothermal vents on fast- spreading mid-ocean ridges are punctuated by frequent physical disturbance. Larval dispersal among disjunct vent sites facilitates the persistence of sessile invertebrate species in these geolog...

A. J. Fusaro

2008-01-01

35

Explore life at a hydrothermal vent  

NSDL National Science Digital Library

These video clips introduce Earth science students to a variety of creatures that inhabit hydrothermal vents on the ocean floor. The introduction describes how scientists captured the images using submarines and remote cameras. The first video is a three-dimensional animation that shows the landscape of the ocean floor. Five live-action clips show sulfide particles erupting from the vents, tube worms retreating from the camera, and plant-like sulfide worms that appear to be fighting. Students also see close-up views of an octopus eye and the tiny pandorae worms that live on the larger tube worms. A descriptive caption accompanies each video. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

36

A Biogeographical Perspective of the Deep-Sea Hydrothermal Vent Fauna  

Microsoft Academic Search

Biogeography seeks to distinguish patterns in the distribution of species and to determine causal processes. Hydrothermal vent habitats have several properties that invite biogeographic studies: constrained to active deep-sea ocean ridges, known in most oceans and anticipated in the rest, patchy in distribution, extreme conditions and a limited group of inhabitants. Biologists have studied 30 vent sites mostly in the

Verena Tunnicliffe; Andrew G. McArthur; Damhnait McHugh

1998-01-01

37

Geomicrobiology of Hydrothermal Vents in Yellowstone Lake: Phylogenetic and Functional Analysis suggest Importance of Geochemistry (Invited)  

NASA Astrophysics Data System (ADS)

Yellowstone Lake (Yellowstone National Park, WY, USA) is a large, high-altitude, fresh-water lake that straddles the most recent Yellowstone caldera, and is situated on top of significant hydrothermal activity. An interdisciplinary study is underway to evaluate the geochemical and geomicrobiological characteristics of several hydrothermal vent environments sampled using a remotely operated vehicle, and to determine the degree to which these vents may influence the biology of this young freshwater ecosystem. Approximately six different vent systems (locations) were sampled during 2007 and 2008, and included water obtained directly from the hydrothermal vents as well as biomass and sediment associated with these high-temperature environments. Thorough geochemical analysis of these hydrothermal environments reveals variation in pH, sulfide, hydrogen and other potential electron donors that may drive primary productivity. The concentrations of dissolved hydrogen and sulfide were extremely high in numerous vents sampled, especially the deeper (30-50 m) vents located in the Inflated Plain, West Thumb, and Mary Bay. Significant dilution of hydrothermal fluids occurs due to mixing with surrounding lake water. Despite this, the temperatures observed in many of these hydrothermal vents range from 50-90 C, and elevated concentrations of constituents typically associated with geothermal activity in Yellowstone are observed in waters sampled directly from vent discharge. Microorganisms associated with elemental sulfur mats and filamentous ‘streamer’ communities of Inflated Plain and West Thumb (pH range 5-6) were dominated by members of the deeply-rooted bacterial Order Aquificales, but also contain thermophilic members of the domain Archaea. Assembly of metagenome sequence from the Inflated Plain vent biomass and to a lesser extent, West Thumb vent biomass reveal the importance of Sulfurihydrogenibium-like organisms, also important in numerous terrestrial geothermal outflow channels of YNP. Analysis of functional genes present in the consensus metagenome sequence representing these populations indicate metabolic potential for oxidation of reduced sulfur and hydrogen, both of which are present at high concentrations in these vent ecosystems. Metagenome sequence of biomass associated with sediments from hydrothermal vents at Mary Bay (50 m depth) suggest greater archaeal and bacterial diversity in this environment, which may be due to higher concentrations of hydrogen, iron, and manganese measured in these environments. Results from metagenome sequence and modest 16S rRNA gene surveys from hydrothermal vent biomass indicate that several groups of novel thermophilic archaea inhabit these sites, and in many cases, are represented by organisms not found in YNP terrestrial geothermal environments that have been characterized to date. The hydrothermal vents from Inflated Plain and West Thumb indicate a linkage between various geochemical attributes (sulfide, hydrogen) and the metabolic potential associated with dominant Aquificales populations present in these communities.

Inskeep, W. P.; Macur, R.; Jay, Z.; Clingenpeel, S.; Tenney, A.; Lavalvo, D.; Shanks, W. C.; McDermott, T.; Kan, J.; Gorby, Y.; Morgan, L. A.; Yooseph, S.; Varley, J.; Nealson, K.

2010-12-01

38

Manganese scavenging and oxidation at hydrothermal vents and in vent plumes  

Microsoft Academic Search

Hydrothermal vents provide a major source of dissolved Mn(II) to the oceans, where concentrations range from 5 mM within the 350°C hot smokers to just above ambient seawater concentration in far field vent plumes. The Mn(II)-rich environments within warm vents and vent plumes provide a suitable habitat for Mn(II) oxidizing bacteria. In order to compare rates of scavenging and oxidation

Kevin W. Mandernack; Bradley M. Tebo

1993-01-01

39

Genetic differentiation between spatially-disjunct populations of the deep-sea, hydrothermal vent-endemic amphipod Ventiella sulfuris  

Microsoft Academic Search

Species endemic to deep-sea hydrothermal vent ecosystems have disjunct distributions imposed by the island-like arrangement of their specialized habitats. Using allozyme electrophoresis, we examined genetic population structure of the hydrothermal vent amphipod Ventiella sulfuris Barnard and Ingram, 1990. Samples from five sites along the East Pacific Rise (EPR) and two along the Galapagos Rift were collected in 1990 and 1988,

S. C. France; R. R. Hessler; R. C. Vrijenhoek

1992-01-01

40

Macrofauna of shallow hydrothermal vents on the Arctic Mid-Ocean Ridge at 71N  

NASA Astrophysics Data System (ADS)

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. Specialized vent fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered hydrothermal vents on the Mohns Ridge north of Jan Mayen. The venting fields are located at 71°N and the venting takes place within two main areas separated by 5 km. The shallowest vent area is at 500-550 m water depth and is located at the base of a normal fault. This vent field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major vent sites each with multiple chimney constructions discharging up to 260°C hot fluids. A large area of diffuse, low- temperature venting occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The hydrothermal vent sites do not show any high abundance of specialized hydrothermal vent fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in hydrothermal vent areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the vent area. The macrofauna found in the vent area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the vents and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also ben found. The crinoid Heliometra glacialis is dominating large areas surrounding the vent fields. Calcareous sponges were common in the area. Calcareous sponges normally represent only a minor fraction of the sponge fauna and it was therefore a big surprise that eight out of a total of 13 species reported here are calcareans. Annelids were the most speciose group with more than 80 identified species, followed by crustaceans. Possible explanations for the lack of typical vent fauna is discussed.

Schander, C.; Rapp, H. T.; Pedersen, R. B.

2007-12-01

41

Hyperthermophilic life at deep-sea hydrothermal vents  

Microsoft Academic Search

The discovery of deep-sea hydrothermal vents in 1977 considerably modified the views on deep-sea biology. For the first time, an ecosystem totally based on primary production achieved by chemosynthetic bacteria was discovered. Besides the warm vents where dense invertebrate communities and their symbiotic bacteria are located, the “black smokers” venting fluids at temperatures up to 350°C were also investigated by

Daniel Prieur; Gaël Erauso; Christian Jeanthon

1995-01-01

42

Metal flux from hydrothermal vents increased by organic complexation  

Microsoft Academic Search

Hydrothermal vents in the sea floor release large volumes of hot, metal-rich fluids into the deep ocean. Until recently, it was assumed that most of the metal released was incorporated into sulphide or oxide minerals, and that the net flux of most hydrothermally derived metals to the open ocean was negligible. However, mounting evidence suggests that organic compounds bind to

Sylvia G. Sander; Andrea Koschinsky

2011-01-01

43

Euryhaline Halophilic Microorganisms From the Suiyo Seamount Hydrothermal Vents.  

NASA Astrophysics Data System (ADS)

The euryhaline halophilic microorganisms grow in a wide salinity range from <3% NaCl (seawater equivalent) to >15% NaCl or to even saturation (about 30% NaCl). A number of euryhaline halophiles have been found in a wide range of habitats from oceanic and terrestrial regimes, from deep-sea vents and seeps, and from Antarctic sea ice and terrains. We have isolated the euryhaline strains independently from a Mid-Atlantic Ridge vent fluids and Antarctic terrains are closely related species of the genus Halomonas. Some euryhaline halophiles maintain intracellular osmotic balance by controlling the concentration of compatible solute such as ectoine. This compatible solute not only stabilizes the proteins from denaturation caused by high salt concentration but also serves as a protectant against stresses such as heating, freezing and drying. The sub-seafloor structure of a hydrothermal vent is highly complicated with mosaic heterogeneity of physicochemical parameters such as temperature and salinity. This premise led us to the hypothesis that some euryhaline halophiles including Halomonas species well adapt to a wide salinity-ranged habitat in the sub-vent. To test this hypothesis, isolation and characterization of euryhaline halophiles from the Suiyo Seamount hydrothermal vents were conducted the drill-cored rock samples from the sites APSK-02, 03, and 07 and the filter-trapped fluid particle samples from the sites APSK-01 and 05 were used. For initial cultivation, a heterotrophic bacterial medium of 15% NaCl was used. The samples was added to the medium and incubated under both aerobic and anaerobic conditions at room temperature. A total of 5 euryhaline halophilic strains were obtained and phylogenetically characterized: two strains (both related to Marinobacter) from APSK-02 core section 2; one strain (related to H. meridiana) from APSK-07 core section 3; and two strains (related to H. meridiana and H. variabilis) from APSK-01 trapped particles. In addition, some thermophilic halophiles that grow at 20% NaCl and 90 degree C were isolated from APSK-02, although phylogenetic and physioloigcal studies are under way. This research was supported by Archean Park project.

Okamoto, T.; Kimura, H.; Maruyama, A.; Naganuma, T.

2002-12-01

44

Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming  

SciTech Connect

Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized by unique, chemotropic biologic communities and suggest that hydrothermal input plays an important role in the nutrient dynamics of the lake's ecosystem. The main concentration of hydrothermal activity occurs in the northeast region of the main lake body in a number of locations including: (1) along the shoreline from the southern edge of Sedge Bay to the inlet of Pelican Creek; (2) the central portion of the partially submerged Mary Bay phreatic explosion crater, within deep (30--50 m) fissures; (3) along the top of a 3 km long, steep-sided ridge that extends from the southern border of Mary Bay, south-southeast into the main lake basin; and (4) east of Stevenson Island along the lower portion of the slope (50--107 m) into the lake basin, within an anastomosing series of north to northwest trending, narrow troughs or fissures. Hydrothermal vents were also located within, and surrounding the West Thumb of Yellowstone Lake, with the main concentration occurring the offshore of the West Thumb and Potts Geyser Basin. Hydrothermal vents in Yellowstone Lake occur along fractures that have penetrated the lake sediments or along the tops of ridges and near shore areas. Underneath the lake, rising hydrothermal fluids encounter a semi-permeable cap of lake sediments. Upwardly convecting hydrothermal fluid flow may be diverted by the impermeable lake sediments along the buried, pre-existing topography. These fluids may continue to rise along topography until fractures are encountered, or the lake sediment cover is thinned sufficiently to allow egress of the fluids.

Kaplinski, M.A.; Morgan, P. (Northern Arizona Univ., Flagstaff, AZ (United States). Geology Dept.)

1993-04-01

45

Silica and germanium in Pacific Ocean hydrothermal vents and plumes  

NASA Astrophysics Data System (ADS)

Dissolved silica (Si) and inorganic germanium (Ge) concentrations were measured in hydrothermal fluids from black smoker vents on the East Pacific Rise (21 deg N EPR) and the Southern Juan de Fuca Ridge (45 deg N SJdFR: North and South Cleft Sites, Axial Volcano). These typically display end-member concentrations ranging from 16 to 23 mM (Si) and 150 to 280 nM (Ge), and end-member Ge/Si ratios clustering between 8 and 14 x 10(exp -6), more than 10-fold greater than the ratio entering the ocean via rivers (0.54 x 10(exp -6)) and being recycled in seawater (0.7 x 10(exp -6)). `Excess' concentrations of dissolved Si and Ge above oceanic background are observed in mid-water hydrothermal plumes over mid-ocean ridge (MOR) spreading centers on the Southern EPR (SEPR) (10 deg - 20 deg S) and the SJdFR. The largest Si and Ge concentration anomalies occur over the North Cleft Segment of the SJdFR. These are a factor of three greater than anomalies over the SEPR (10 deg - 20 deg S). Excess Ge correlates with excess He-3 in plumes at a Ge/He-3 molar ratio of about 1 x 10(exp 4), approximately the same ratio as in black smokers. These observations, combined with low abundances of Ge in Fe-Mn-rich metalliferous sediments, suggest that Ge (and Si) behave conservatively in mid-ocean ridge hydrothermal plumes. A simple ocean Si and Ge balance, constrained by the global river silica flux and Ge/Si ratios in hydrothermal vents, rivers and biogenic silica, suggests that the global hydrothermal silica flux is about 1 - 4 x 10(exp 11) mole/yr, much lower than that estimated from He-3. Either (1) 70 - 80% of the Ge flux to the ocean is removed in as-yet undiscovered sinks (not opal), or (2) only 10% of the mantle to ocean He-3 and heat fluxes is associated with MOR hydrothermal convection through the 350 C isotherm (90% is off-ridge), or (3) the oceanic Ge/Si, He-3 (and Sr-87/Sr-86) balances today are far from steady-state.

Mortlock, Richard A.; Froelich, Philip N.; Feely, Richard A.; Massoth, Gary J.; Butterfield, David A.; Lupton, John E.

1993-09-01

46

Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough  

NASA Astrophysics Data System (ADS)

In 2000, an active hydrothermal site, venting high-temperature fluid up to 300 oC, was discovered by Shinkai 6500 on the top of Yonaguni Knoll IV during YK 00-06 cruise in Okinawa Trough. During the subsequent subseafloor survey using Shinkai 6500 in 2003 (YK03-05), vents of liquid CO2 droplets were found at the site. Similar liquid CO2 droplets had previously been found at the active hydrothermal sites at JADE hydrothermal field, Okinawa Trough, during the extensive seafloor survey using submersibles in 1989 [Sakai et al., 1990]. Besides, similar liquid CO2 venting has also been recognized in NW Eifuku hydrothermal site on Izu-Bonin- Mariana arc. It thus appears that liquid CO2 venting might be usual phenomenon in some submarine arc volcanoes. The detailed relation between seafloor venting liquid CO2 and the surrounding high-temperature hydrothermal fluid, however, was not clarified in their studies. Furthermore, no definite evidence was obtained for the presence of CO2-hydrate in the subsurface. In this study, in order to discuss the subseafloor processes responsible for producing liquid CO2 at the Yonaguni Knoll IV site, as well as the possibility of the occurrence of solid CO2-hydrate within the sediments, we determined the chemical and isotopic compositions of the liquid CO2 found on the site, as well as those in hydrothermal fluid venting from the surrounding chimneys. In consequence, the ^13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the hydrothermal fluid, suggesting that the liquid CO2 must be derived from the hydrothermal fluid. While showing homogeneous ^13C, the hydrothermal fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of hydrothermal fluid due to boiling, formation of solid CO2- hydrate due to cooling of vapor phase, and melting of the solid CO2-hydrate to liquid CO2 due to a temperature increase within the sedimentary layer.

Konno, U.; Tsunogai, U.; Nakagawa, F.; Nakaseama, M.; Ishibashi, J.; Nunoura, T.; Nakamura, K.

2006-12-01

47

Colonization of nascent, deep-sea hydrothermal vents by a novel Archaeal and Nanoarchaeal assemblage.  

PubMed

Active deep-sea hydrothermal vents are areas of intense mixing and severe thermal and chemical gradients, fostering a biotope rich in novel hyperthermophilic microorganisms and metabolic pathways. The goal of this study was to identify the earliest archaeal colonizers of nascent hydrothermal chimneys, organisms that may be previously uncharacterized as they are quickly replaced by a more stable climax community. During expeditions in 2001 and 2002 to the hydrothermal vents of the East Pacific Rise (EPR) (9 degrees 50'N, 104 degrees 17'W), we removed actively venting chimneys and in their place deployed mineral chambers and sampling units that promoted the growth of new, natural hydrothermal chimneys and allowed their collection within hours of formation. These samples were compared with those collected from established hydrothermal chimneys from EPR and Guaymas Basin vent sites. Using molecular and phylogenetic analysis of the 16S rDNA, we show here that at high temperatures, early colonization of a natural chimney is dominated by members of the archaeal genus Ignicoccus and its symbiont, Nanoarchaeum. We have identified 19 unique sequences closely related to the nanoarchaeal group, and five archaeal sequences that group closely with Ignicoccus. These organisms were found to colonize a natural, high temperature protochimney and vent-like mineral assemblages deployed over high temperature outflows within 92 h. When compared phylogenetically, several of these colonizing organisms form a unique clade independent of those found in mature chimneys and low-temperature mineral chamber samples. As a model ecosystem, the identification of pioneering consortia in deep-sea hydrothermal vents may help advance the understanding of how early microbial life forms gained a foothold in hydrothermal systems on early Earth and potentially on other planetary bodies. PMID:16343327

McCliment, Elizabeth A; Voglesonger, Kenneth M; O'Day, Peggy A; Dunn, Eileen E; Holloway, John R; Cary, S Craig

2006-01-01

48

A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents.  

PubMed

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 degrees 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. PMID:16871216

Reysenbach, Anna-Louise; Liu, Yitai; Banta, Amy B; Beveridge, Terry J; Kirshtein, Julie D; Schouten, Stefan; Tivey, Margaret K; Von Damm, Karen L; Voytek, Mary A

2006-07-27

49

A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents  

USGS Publications Warehouse

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.

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

2006-01-01

50

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

51

Larval dispersal via entrainment into hydrothermal vent plumes  

NASA Astrophysics Data System (ADS)

One of the most intriguing ecological questions remaining unanswered about hydrothermal vents is how vent organisms disperse and persist. Because vent species are generally endemic and their habitat is patchy and ephemeral on time scales as short as decades, they must disperse frequently, presumably in a planktonic larval stage. We suggest that dispersal occurs not only in near-bottom currents but also several hundred meters above the seafloor at the level of the laterally spreading hydrothermal plumes. Using a standard buoyant plume model and observed larval abundances near hydrothermal vents at 9°50'N along the East Pacific Rise, we estimate a mean vertical flux of approximately 100 vent larvae/h at a single black smoker. Larval abundances were extremely variable near vents, resulting in a range in estimated fluxes of at least an order of magnitude. The suitability of the plume model for these calculations was determined by releasing dyes (fluorescein and rhodamine) as larval mimics into a black smoker plume. The plume model predicted dye fluxes in the plume adequately, given the short averaging times of our measurements and the difficulty of sampling the plume centerline. Our calculations of substantial numbers of vent larvae entrained into the plume support the idea that transport in the lateral plume is an important mechanism of dispersal. Because vertical shear in flows above vents can cause larval dispersal trajectories in the plume to deviate considerably from those along the seafloor, larvae in the plume may have access to habitats that are unreachable by larvae in near-bottom flows.

Kim, Stacy L.; Mullineaux, Lauren S.; Helfrich, Karl R.

1994-06-01

52

A new Western Pacific Tonguefish (Pleuronectiformes: Cynoglossidae): The first Pleuronectiform discovered at active Hydrothermal Vents  

Microsoft Academic Search

Symphurus thermophilus n. sp., described from 16 specimens collected by submersibles, ROV, epibenthic sled and dredge, occurs on a variety of substrata at several active hydrothermal sites located at 239-733 m between 21°N and 35°S in the western Pacific Ocean. Symphurus thermophilus, the only pleuronectiform fish known to inhabit hydrother- mal vent areas, is characterized by the combination of a

THOMAS A. MUNROE; JUN HASHIMOTO

53

Hydrothermal Vents at 5000m on the Mid-Cayman Rise: The Deepest and Hottest Hydrothermal Systems Yet Discovered!  

NASA Astrophysics Data System (ADS)

This contribution describes the geological setting of hydrothermal activity within the Mid- Cayman Rise (MCR) using data acquired during cruise JC044 (MAR-APR 2010) from the deep-towed sidescan sonar TOBI, AUV Autosub6000 and the ROTV HyBIS. The 110 km-long Mid- Cayman Rise (MCR), located within Caribbean Sea, is the deepest spreading centre known, reaching over 6000m. Hence it poses an end-member of extreme depth for hydrothermal circulation. Accretion of new volcanic crust is focused within two ridge segments, to the north and south of a centrally located massif of peridotite and gabbro. Following earlier indications of hydrothermal plumes (German et al., in 2009), we discovered two high-temperature hydrothermal system: one at a depth of 5000m in the neovolcanic zone of the northern segment, and another at 2300m on the flanks of the MCR. These sites show contrasting styles of fluid venting, mineralisation, geological setting and host rock interaction. At 5000m-depth, the ultra-deep vent site forms the deepest hydrothermal system known. Venting is focused at the western side of a 100m diameter, 30m high mound, while inactive sulphides extend eastwards for at least 800m. Fluids discharge from clusters of chimneys whose location is related to basement faults. Changes in salinity in the venting fluids indicate discharge of a low salinity phase and a brine phase. At 500bar, this is definitive evidence for supercritical fluid emission. We also found the sulphide mineralization to be copper-rich, giving a characteristic green hue to many of the deposits, probably a result of the super-critical state of the vent fluids. A prominent axial volcanic ridge nearby indicates a robust magma supply to the northern MCR segment. Thus it is likely the ultra-deep vent site derives its thermal energy from magmatic sources, similar to those thought to underlie other slow-spreading ridge volcanic-hosted vent sites (e.g. Broken Spur: MAR). The shallower (2300m) MCR hydrothermal vent site hosts vigorous medium-temperature fluid discharge from sulphide chimneys at the summit of an 80m diameter sulphide mound. Exiting vent fluids are mostly clear with only traces of sulphide particulates. The chimneys are composed predominately of iron sulphides and calcium sulphate, with estimated fluid temperatures in the region of 150-250°C. The vent site is located on a peridotite ± gabbro massif (Mt Dent), forming the western flank of the MCR. The morphology and lithology of Mt Dent indicates that it is an oceanic core complex, but in a ‘dying’ stage. The axial volcanic ridge to the north has propagated into the OCC foot-wall and probably supplies the heat driving the hydrothermal system. The only detectable signature from this vent field is its low Eh plume. As a result, we believe that this style of venting has hitherto been overlooked, and thus its global significance for the cooling and alteration of slow-spread oceanic crust may be greatly underestimated.

Murton, B. J.; Connelly, D. P.; Copley, J. T.; Stansfield, K. L.; Tyler, P. A.; Cruise Jc044 Sceintific Party

2010-12-01

54

Larval abundance and dispersal at deep-sea hydrothermal vents in the southern Mariana Trough  

NASA Astrophysics Data System (ADS)

Since the discovery of deep-sea hydrothermal vents over thirty years ago, scientists have been perplexed by the question: “How are the faunal populations established and maintained at these very discrete and often ephemeral habitats?” For the animals that are sessile or have limited mobility as adults, dispersal to these habitats occurs early in the life cycle, as planktonic larvae in the water column. Due to the difficulties in sampling deep-sea larvae, including low abundances (dilute concentrations), we have very few quantitative estimates of larval dispersal between or larval supply to hydrothermal vents. Here, we will present results of an international, collaborative effort to study larval abundance and dispersal at vents near the back-arc spreading center in the southern Mariana Trough. On R/V Yokosuka cruise YK10-11 in September 2010, we will deploy large-volume plankton pumps at approximately 3000-m depth at Snail (also called South Backarc), Archaean, and Pika, three of the Vents (Volcanic) Unit sites in the U.S. Marianas Trench Marine National Monument. These vents are being studied as part of the Japanese multi-disciplinary program TAIGA (Trans-crustal Advection and In-situ biogeochemical proceses of Global sub-sea floor Aquifer). These will be the first collections of vent larvae in the Mariana back-arc, and we will compare the abundances and diversity of larvae to similar work conducted at the Ridge 2000 East Pacific Rise Integrated Studies Site. We will deploy a current meter near the Snail site (on-axis) for preliminary estimates of passive larval transport on the time scale of the cruise. The three study sites are situated in a line perpendicular to the back-arc spreading axis, and thus may be interesting in terms of local dispersal processes. Perhaps more interesting, however, is that the back-arc vents that we will visit are as close as 25 km to known vents on the arc, yet 600 km south of the other known vents in the back-arc. These two tectonic settings create different habitat conditions and support vent communities with different species composition. Will we collect larvae of species that are commonly found at (generally shallower) vents on the Mariana arc? The larval studies will help address the question of how populations of vent-endemic species are connected at hydrothermal vents within the new Marine National Monument.

Beaulieu, S. E.; Watanabe, H.; Mills, S. W.; Pradillon, F.; Kojima, S.; Mullineaux, L. S.

2010-12-01

55

Predation Structures Communities at Deep-Sea Hydrothermal Vents  

Microsoft Academic Search

The structure and dynamics of natural communities result from the interplay of abiotic and biotic factors. We used manipulative field experiments to determine the relative roles of abiotic conditions and biotic interactions in structuring deep-sea (2500 m depth) communities along environmental gradients around hydrothermal vents of the eastern tropical Pacific Ocean (East Pacific Rise, at 9 50 N). We tested

Fiorenza Micheli; Charles H. Peterson; Lauren S. Mullineaux; Charles R. Fisher; Susan W. Mills; Gorka Sancho; Galen A. Johnson; Hunter S. Lenihan

2002-01-01

56

Experimental ecology at deep-sea hydrothermal vents: a perspective  

Microsoft Academic Search

In situ and laboratory experiments conducted over the past quarter of a century have greatly increased our understanding of the ecology of deep-sea hydrothermal systems. Early experiments suggested that chemosynthetic primary production constituted the principal source of organic matter for biological communities associated with vents, although subsequent studies have revealed many complexities associated with interactions between microbes and higher organisms

Cindy Lee Van Dover; Richard A Lutz

2004-01-01

57

In Situ Materials Study in Hot Hydrothermal Vent Fluid  

Microsoft Academic Search

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

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

2004-01-01

58

Anaerobic Spirochete from a Deep-Sea Hydrothermal Vent  

PubMed Central

An obligately anaerobic spirochete, designated strain GS-2, was selectively isolated from samples collected at a deep-sea (2,550 m) hydrothermal vent of the Galapagos Rift ocean floor spreading center. The morphological and physiological characteristics of strain GS-2 resembled those of Spirochaeta strains. However, strain GS-2 failed to grow consistently in any liquid medium tested. In addition, strain GS-2 grew more slowly and to lower yields than other Spirochaeta species. The occurrence of obligately anaerobic bacteria in hydrothermal vents indicates that the water in at least some of the vent areas is anoxic. The presence of strain GS-2 shows that these areas are favorable for anaerobic marine spirochetes. Images

Harwood, C. S.; Jannasch, H. W.; Canale-Parola, E.

1982-01-01

59

Conditions for high-temperature off-axis venting at the Logatchev 1 hydrothermal field  

NASA Astrophysics Data System (ADS)

The off-axis Logatchev hydrothermal field at 14°45'N at the Mid Atlantic Ridge consists of several vent sites in an ultramafic environment. Here we focus on the Logatchev 1 site, which is located 7km off-axis. Hydrothermal fluids are discharging at 300-360°C (Petersen et al., 2009) and a recent seismic study revealed intense off-axis seismic activity along fault planes dipping towards the ridge axis. But how can high-temperature venting be sustained several kilometers off-axis and what is the heat source driving hydrothermal flow? We have conducted a numerical modeling study of the Logatchev 1 hydrothermal field to answer these questions. We use a 2D FE-FV model, which resolves for hydrothermal flow of pure water. The model is instructed by geophysical data (bathymetry, fault location, depth of the heat source) and a basal heat flux boundary condition according to the total heat input of slow-spreading ridges. During systematic model runs we have varied the position of the heat source as well as fault and background permeability. Only a narrow range of model parameters is consistent with observations. In order to get off-axis hydrothermal venting the driving heat-source cannot be located on-axis. It has to be located between the region affected by faulting and the vent field. Under these conditions, hydrothermal fluids will ascent towards the seafloor along the fault planes. Vent temperatures can be used as proxy for permeability. Driesner (2010) pointed out that there is an inverse correlation between matrix permeability and vent temperature. For Logatchev 1 we need a low background permeability in order to heat pore fluids to temperatures higher than 300°C and a higher fault permeability in order to rapidly transport them to the seafloor. We find that 2x10-16 m2 as background and 1x10-14 m2 as fault permeability yields the best results. In summary, we find that the combination of geophysical data with numerical modeling can help understanding sub-surface flow pattern beneath the Logatchev 1 hydrothermal field. Only a narrow range of off-axis heat source locations are consistent with venting at Logatchev 1. The discharge system is controlled by faults, while recharge occurs either through faults or over a wider area.

Andersen, Christine; Rüpke, Lars; Grevemeyer, Ingo; Petersen, Sven

2013-04-01

60

The isotopic composition of dissolved inorganic nitrogen in hydrothermal vent fluids  

NASA Astrophysics Data System (ADS)

Hydrothermal vent systems at mid-ocean ridges are sites with rapid rates of biomass production, sustained by chemolithoautotrophic bacteria at the base of the vent community food chains. The exact metabolic pathways, in particular those that involve nitrogen (N), and the rates at which the metabolic reactions take place are poorly constrained. In previous studies, very low 15N/14N ratios have been attributed to strong N isotope fractionation during chemosynthetic assimilation of ammonium. However, actual data on the N isotopic composition of dissolved inorganic N in vent systems, which could provide coherent information on the sources of N during chemolithoautotrophic biosynthesis, do not exist. Furthermore, the fate of hydrothermally discharged ammonium as well as that of nitrate that is mixed in from the ocean water column have not been the focus of much attention. As a consequence, little is known about N-cycle reactions within hydrothermal vent systems. We will present nitrate isotope (15N/14N and 18O/16O) data from various sites at Axial Volcano on the Juan de Fuca ridge. Their integration with nitrate concentration data suggests non-conservative behavior of nitrate along temperature gradients. Highest N and O isotope ratios (7.6 permil and 21.0 permil, respectively) are found in average diffuse fluids (17°C). Elevated N and O isotope ratios were associated with decreased nitrate concentrations and indicate a nitrate consuming process that fractionates both N and O isotopes. The ratio of 15N versus 18O enrichment in residual nitrate is, however, not consistent with previous reports on nitrate N versus O isotope fractionation during denitrification in the suboxic ocean water column, implying anomalous N and O isotope fractionation during denitrification in hydrothermal vent fluids and/or the presence of additional microbially mediated N transformations that affect the N and O isotope composition of the nitrate pool in the Axial hydrothermal vent system in a fundamentally different way. More nitrate isotope measurements from other hydrothermal vent systems will be conducted in order to investigate the possible mechanisms behind the observed N-to-O nitrate isotope anomaly. In addition, we plan to present data on the N isotopic composition of ammonium from ammonium-rich vent fluids from the Endeavour segment of the Juan de Fuca ridge (upcoming cruise Aug. 13 to Sep. 8). We anticipate that the assessment of principal patterns of ammonium N-isotope dynamics at Endeavour sites will help to study the activity of ammonium oxidizing organisms, as well as to gain constraints on the source of N during bacterial N assimilation in this particular geomicrobial ecosystem.

Lehmann, M. F.; Bourbonnais, A.; Butterfield, D. A.

2006-12-01

61

First hydrothermal active vent discovered on the Galapagos Microplate  

NASA Astrophysics Data System (ADS)

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.

Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

2011-12-01

62

Manganese scavenging and oxidation at hydrothermal vents and in vent plumes  

NASA Astrophysics Data System (ADS)

Hydrothermal vents provide a major source of dissolved Mn(II) to the oceans, where concentrations range from 5 mM within the 350°C hot smokers to just above ambient seawater concentration in far field vent plumes. The Mn(II)-rich environments within warm vents and vent plumes provide a suitable habitat for Mn(II) oxidizing bacteria. In order to compare rates of scavenging and oxidation of Mn(II) proximally within vent fields (<30 m from venting water and temperatures <16°C) and distally within vent plumes, and to determine the relative contribution of microbes, incubation experiments using 54 Mn as a radiotracer were conducted in situ and on collected water samples from three hydrothermal vent locations: the Guaymas basin (GB), the Galapagos spreading center (GA), and the Endeavor Ridge of the Juan de Fuca spreading center (JDF). Both the adsorbed and oxidized fractions of the total 54 Mn scavenged were determined and found to often be significant (as high as 65 and 74%, respectively). Manganese scavenging rates were generally higher in in situ incubations than in incubations conducted on board ship. Inhibition of 54 Mn scavenging by sodium azide provided evidence for microbially mediated Mn(II) uptake and oxidation in waters both proximal (GA and GB) and distal to the vents (GA and JDF), even at distances as great as 17 km from the ridge axis at JDF. The highest manganese scavenging rates were observed within the vent fields (up to 2.5 nM/day). The residence times of dissolved Mn(II) were shorter in the GB and GA vent fields (26 and 28 days) than in the JDF vent field (1.4 years). This difference may be due to different mechanisms of Mn(II) precipitation in operation. At the GA vent field Mn(II) precipitation was often strongly inhibited by sodium azide and therefore apparently due to microbial activity. In contrast, Mn(II) scavenging within the JDF vent field was not significantly affected by sodium azide. Because 54 Mn scavenging in the JDF vent field was dependent on the presence of oxygen and a much larger fraction of the total 54 Mn scavenged was adsorbed than oxidized, manganese scavenging appears to occur primarily by an abiological mechanism, perhaps coprecipitation with iron oxyhydroxides. In comparison to the vent fields, Mn(II) scavenging rates were lower within the vent plumes (<0.6 nM/ day for GA and <0.2 nM/day for JDF), whereas residence times were not significantly different (as low as 34 days for GA and 1.0 years for JDF). The short residence times (90 and 118 days) and high microbial activity measured in bottom waters beneath the vent plumes at GA and JDF probably resulted from enhanced scavenging by manganate-coated bacteria that settled out from the vent plume and accumulated near the bottom. Therefore, bacteria not only enhance the scavenging of Mn within vent waters, but also facilitate Mn deposition to the sediments.

Mandernack, Kevin W.; Tebo, Bradley M.

1993-08-01

63

Observations on parasitism in deep-sea hydrothermal vent and seep limpets.  

PubMed

Parasite burdens of shallow-water molluscs have been well documented, but little is known about parasite burdens of molluscs from deep-sea chemosynthetic environments (e.g. hydrothermal vents and seeps). Chemosynthetic habitats are characterized by high concentrations of reduced sulfur and, in the case of vents, high heavy metal concentrations. These compounds are noxious and even stress-inducing in some environments, but are part of the natural chemical milieu of vents and seeps. To examine parasite types and infection intensities in limpets from vents and seeps we documented parasite burdens in 4 limpet species from 4 hydrothermal vent fields (3 on the East Pacific Rise, 1 on the Mid-Atlantic Ridge) and 1 seep site (Florida Escarpment). Approximately 50 % of all limpets examined were infected with 1 or more types of parasites. Limpet parasites were predominantly rickettsia-like inclusions in the digestive and gill epithelia. Limpets collected from the vent field on the Mid-Atlantic Ridge were free of parasites. We detected no histopathological effects that we could attribute to parasites. PMID:15648827

Terlizzi, Christina M; Ward, Megan E; Van Dover, Cindy L

2004-11-23

64

Permeability-Porosity Relationships in Deep Sea Hydrothermal Vent Deposits  

NASA Astrophysics Data System (ADS)

To map out the thermal and chemical regimes within vent deposits where micro-and macro-organisms reside requires accurate modeling of mixing and reaction between hydrothermal fluid and seawater within the vent structures. However, a critical piece of information, quantitative knowledge of the permeability of vent deposits, and how it relates to porosity and pore geometry, is still missing. To address this, systematic laboratory measurements of permeability and porosity were conducted on 3 large vent structures from the Mothra Hydrothermal vent field on the Endeavor Segment of the Juan de Fuca Ridge. Twenty-five cylindrical cores with diameters of 2.54 cm and various lengths were taken from Phang (a tall sulfide-dominated spire that was not actively venting when sampled), Roane (a lower temperature spire with dense macrofaunal communities growing on its sides that was venting diffuse fluid of < 300° C) and Finn (an active black smoker with a well-defined inner conduit that was venting 302° C fluids prior to recovery (Delaney et al., 2000; Kelley et al, 2000)). Measurements were made to obtain porosity and permeability of these drill cores using a helium porosimeter (UltraPoreTM300) and a nitrogen permeameter (UltrapermTM400) from Core Laboratories Instruments. The porosimeter uses Boyle's law to determine pore volume from the expansion of a know mass of helium into a calibrated sample holder, whereas the permeameter uses Darcy's law to determine permeability by measuring the steady-state flow rate through the sample under a given pressure gradient. A moderate confining pressure of 1.38 MPa was applied during the measurements to prevent leakage between the sample surface and the sample holder. The permeability and porosity relationship is best described by two different power law relationships with exponents of ˜9 (group I) and ˜3 (group II), respectively. Microstructural observations suggest that the difference in the two permeability-porosity relationships reflects different evolution processes as pores are sealed within different parts of the vent structures. Our data suggest that correctly identifying the processes of pore space evolution in seafloor vent deposits is the key to successfully relating permeability to porosity.

Zhu, W.; Gittings, H.; Tivey, M. K.

2003-12-01

65

Brachiopods from Ancient Hydrocarbon Seeps and Hydrothermal Vents  

Microsoft Academic Search

\\u000a Brachiopods are well-established as components of ancient ­chemo­synthesis-dominated environments: hydrocarbon seeps and hydrothermal\\u000a vents. The focus here is primarily on brachiopods recorded from hydrocarbon seeps from the Palaeozoic and Mesozoic although\\u000a records from the Cenozoic are being reported. In hydrocarbon seeps brachiopods have played a central role forming shell-beds\\u000a that may be a few meters in vertical thickness and up

Michael R. Sandy

66

Sulfur Oxidation at Deep-Sea Hydrothermal Vents  

Microsoft Academic Search

Microbial oxidation of geothermally produced reduced sulfur compounds is at the nexus of the biogeochemical carbon and sulfur\\u000a cycles at deep-sea hydrothermal vents. Available information indicates that microbial symbionts and free- living gammaproteobacteria\\u000a of the genera Thiomicrospira, Halothiobacillus, and Beggiatoa are important sulfur-oxidizers above the seafloor at these systems. In addition, bacteria belonging to the Epsilonproteobacteria have been identified as

Stefan M. Sievert; Michael Hügler; Craig D. Taylor; Carl O. Wirsen

67

In Situ Materials Study in Hot Hydrothermal Vent Fluid  

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

68

Sulfide Oxidation across Diffuse Flow Zones of Hydrothermal Vents  

Microsoft Academic Search

The sulfide (H2S\\/HS?) that is emitted from hydrothermal vents begins to oxidize abiotically with oxygen upon contact with ambient bottom water,\\u000a but the reaction kinetics are slow. Here, using in situ voltammetry, we report detection of the intermediate sulfur oxidation\\u000a products polysulfides [$$ {\\\\text{S}}_{\\\\text{x}}^{2 - } $$] and thiosulfate [$$ {\\\\text{S}}_{ 2} {\\\\text{O}}_{ 3}^{ 2- } $$], along with contextual

Amy Gartman; Mustafa Yücel; Andrew S. Madison; David W. Chu; Shufen Ma; Christopher P. Janzen; Erin L. Becker; Roxanne A. Beinart; Peter R. Girguis; George W. Luther

2010-01-01

69

Hyperthermophilic life at deep-sea hydrothermal vents  

NASA Astrophysics Data System (ADS)

The discovery of deep-sea hydrothermal vents in 1977 considerably modified the views on deep-sea biology. For the first time, an ecosystem totally based on primary production achieved by chemosynthetic bacteria was discovered. Besides the warm vents where dense invertebrate communities and their symbiotic bacteria are located, the "black smokers" venting fluids at temperatures up to 350°C were also investigated by microbiologists. Several strains of hyperthermophilic Archaea (methanogens, sulfate-reducers, sulfur-reducers) were isolated from smokers and surrounding materials. Deep-sea isolates that have been totally described, have been assigned to new species, within genera previously found in coastal geothermally heated environments. However, some species appear to exist in both deep and shallow ecosystems. Some deep-sea hyperthermophiles appear to be adapted to hydrostatic pressure and showed a barophilic response. The distribution of hyperthermophiles in the hot ecosystems of the planet, and their adaptation to pressure are presented and discussed.

Prieur, Daniel; Erauso, Gaël; Jeanthon, Christian

1995-02-01

70

Vertebrate nutrition in a deep-sea hydrothermal vent ecosystem: Fatty acid and stable isotope evidence  

NASA Astrophysics Data System (ADS)

The hydrothermal vent zoarcid fish Thermarces cerberus is a top predator that inhabits deep-sea hydrothermal vents on the East Pacific Rise (EPR). Bacterial chemoautotrophy at these sites supports abundant animal communities. Paradoxically, these chemoautotrophic bacteria are not known to produce polyunsaturated fatty acids (PUFA), dietary nutrients essential for all marine vertebrates. To understand how T. cerberus successfully exploits the vent environment and obtains essential PUFA, we compared its fatty acid composition to those of its invertebrate prey. Levels of 20:5(n-3) and 22:6(n-3) in muscle and ovary tissues of T. cerberus were low and contained higher amounts of 20:5(n-3) than 22:6(n-3). This is in contrast to most marine fish where 22:6(n-3) typically dominates. Prey items include the limpet ( Lepetodrilus elevatus) and amphipods ( Halice hesmonectes and Ventiella sulfuris) and all contained PUFA dominated by 20:5(n-3) in amounts likely to support the requirements of T. cerberus. ?C13 values of 20:5(n-3) in the invertebrate prey were consistent with synthesis from a chemoautotrophic carbon source within the vent environment. The potential origins of these PUFA are discussed in terms of the nutrition of T. cerberus and more generally in terms of the evolution of vent taxa.

Pond, D. W.; Fallick, A. E.; Stevens, C. J.; Morrison, D. J.; Dixon, D. R.

2008-12-01

71

Indigenous ectosymbiotic bacteria associated with diverse hydrothermal vent invertebrates.  

PubMed

Symbioses involving bacteria and invertebrates contribute to the biological diversity and high productivity of both aquatic and terrestrial environments. Well-known examples from chemosynthetic deep-sea hydrothermal vent environments involve ectosymbiotic microbes associated with the external surfaces of marine invertebrates. Some of these ectosymbioses confer protection or defence from predators or the environment itself, some are nutritional in nature, and many still are of unknown function. Several recently discovered hydrothermal vent invertebrates, including two populations of yeti crab (Kiwa spp.), a limpet (Symmetromphalus aff. hageni), and the scaly-foot snail (as yet undescribed), support a consortium of diverse bacteria. Comparisons of these ectosymbioses to those previously described revealed similarities among the associated microorganisms, suggesting that certain microbes are indigenous to the surfaces of marine invertebrates. In particular, members of the Thiovulgaceae (epsilonproteobacteria) and Thiotrichaceae (gammaproteobacteria) appear to preferentially form ectosymbioses with vent crustaceans and gastropods. Interactions between specific Proteobacteria and the surfaces of many marine invertebrates likely have ecological and evolutionary significance at these chemically challenging habitats. PMID:23766219

Goffredi, Shana K

2010-02-08

72

Reactivity landscape of pyruvate under simulated hydrothermal vent conditions.  

PubMed

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

Novikov, Yehor; Copley, Shelley D

2013-07-19

73

A fossil, serpentinization-related hydrothermal vent, Ocean Drilling Program Leg 173, Site 1068 (Iberia Abyssal Plain): Some aspects of mineral and fluid chemistry  

NASA Astrophysics Data System (ADS)

The basement at Site 1068, Ocean Drilling Program (ODP) Leg 173 (serpentinized peridotite in fault contact with overlying amphibolite-clast-dominated sedimentary and tectonic breccias) is host to a hydrothermal system rooted in serpentinization reactions occurring at depth. The serpentinite grades downward from cataclasites at the fault, through brecciated, recrystallized, tochilinite-bearing serpentinite, to awaruite-bearing massive, mesh-textured serpentinite. Andradite is common throughout and is a major sink for iron. The breccias are similarly zoned, from tectonized rocks near the fault upward into sedimentary breccias. Mg-silicate vein assemblages and rodingitized amphibolite clasts near the fault give way to calcite veins and nonpervasive albite-chlorite alteration upsection. Marcasite (± pyrrhotite at the fault) is the sulfide phase and occurs only in the tectonic breccias. Fe oxides are magnetite near the fault and hematite and ferric oxyhydroxides upsection. The zonation reflects mixing of seawater with a fluid whose composition (low fO2, fS2 Si, CO2, high Ca, Fe, Ca/Mg, pH) is controlled by serpentinization reactions. The deepest serpentinites have strongly reduced mineral assemblages that are unusual in a totally serpentinized peridotite. This probably reflects equilibration with a fluid derived from ongoing serpentinization at depth. The upper serpentinites, on through the mineral sequences seen in the breccias reflect increasing input from seawater upsection. Increased fO2 and fS2 stabilizes increasingly S- and O-rich assemblages. Calcite (and ferric oxide) precipitation decreases pH, stabilizing marcasite. Relative to mid-ocean ridge hydrothermal systems, fluids in serpentinite-hosted hydrothermal systems are poor in S and rich in Mg and are unlikely to host large sulfide ore deposits.

Beard, James S.; Hopkinson, Laurence

2000-07-01

74

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

75

Comparison of a New Thiomicrospira Strain from the Mid-Atlantic Ridge with Known Hydrothermal Vent Isolates†  

PubMed Central

A new autotrophic Thiomicrospira strain, MA-3, was isolated from the surface of a polymetal sulfide deposit collected at a Mid-Atlantic Ridge hydrothermal vent site. The DNA homology among three vent isolates, Thiomicrospira crunogena, Thiomicrospira sp. strain L-12, and Thiomicrospira sp. strain MA-3, was 99.3% or higher, grouping them as the same species, T. crunogena (type strain, ATCC 35932). The fact that T. crunogena and Thiomicrospira sp. strain L-12 were isolated from Pacific vent sites demonstrates a cosmopolitan distribution of this species.

Wirsen, C. O.; Brinkhoff, T.; Kuever, J.; Muyzer, G.; Molyneaux, S.; Jannasch, H. W.

1998-01-01

76

Composition of archaeal, bacterial, and eukaryal RuBisCO genotypes in three Western Pacific arc hydrothermal vent systems  

Microsoft Academic Search

We studied the diversity of all forms of the RuBisCO large subunit-encoding gene cbbL in three RuBisCO uncharacterized hydrothermal vent communities. This diversity included the archaeal cbbL and the forms IC and ID, which have not previously been studied in the deep-sea environment, in addition to the forms IA,\\u000a IB and II. Vent plume sites were Fryer and Pika in

Hosam Easa Elsaied; Hiroyuki Kimura; Takeshi Naganuma

2007-01-01

77

Spatial structures of hydrothermal vents and vent-associated megafauna in the back-arc basin system of the Okinawa Trough, western Pacific  

Microsoft Academic Search

Spatial patterns and morphology of hydrothermal vents and the occurrence of vent-associated megafauna were investigated in\\u000a the back-arc basin system of the Okinawa Trough, western Pacific. Amongst hydrothermal vent fields located on the rising slopes\\u000a to the NE and S of the basin, the Iheya North area has been subjected to a series of intensive diving surveys. Hydrothermal\\u000a vents demonstrated

M. Tokeshi

78

Metal influence on metallothionein synthesis in the hydrothermal vent mussel Bathymodiolus thermophilus  

Microsoft Academic Search

The present study reports on the metallothionein expression in the hydrothermal vent mussel Bathymodiolus thermophilus. Metallothioneins (MT) are proteins involved in intracellular metal regulation and conserved throughout the animal kingdom. The hydrothermal vent environment presents peculiarities (high levels of sulfides and metals, low pH, anoxia) that may have driven associated species to develop original evolutionary ways to face these extreme

Yann Hardivillier; Françoise Denis; Marie-Véronique Demattei; Paco Bustamante; Marc Laulier; Richard Cosson

2006-01-01

79

Characterization of a Novel Thermococcus sp. from a Hydrothermal Vent of the Suiyo Seamount  

Microsoft Academic Search

The Suiyo seamount is located at 210 km north-northwest of Chichijima Island of the Izu-Bonin Arc. The hydrothermal vents of the Suiyo seamount discharges hot water as high as 308 degrees. We obtained a novel Thermococcus sp. from the hydrothermal vent and partially characterized it. The Thermococcus sp. was observed as usual coccus in initial stages of culture, but changed

T. Kuwabara; M. Minaba; Y. Iwayama; H. Saida; M. Kamekura; S. Sakaushi; A. Maruyama; J. Ishibashi; I. Inoue

2002-01-01

80

Occurrence and recent long-distance dispersal of deep-sea hydrothermal vent shrimps  

PubMed Central

Deep-sea hydrothermal vents and methane seeps are extreme environments that have a high concentration of hydrogen sulphide. However, abundant unique invertebrates including shrimps of the family Bresiliidae have been found in such environments. The bresiliid shrimps are believed to have radiated in the Miocene (less than 20?Myr); however, the period when and the mechanisms by which they dispersed across the hydrothermal vents and cold seeps in oceans worldwide have not been clarified. In the present study, we collected the deep-sea blind shrimp Alvinocaris longirostris from the hydrothermal vent site in the Okinawa Trough and carried out the first investigation of the 18S rRNA gene of a bresiliid shrimp. The phylogenetic analysis revealed that the bresiliid shrimp is situated at an intermediate lineage within the infraorder Caridea and shows monophyly with palaemonid shrimps, which live in shallow sea and freshwater. Furthermore, the mitochondrial cytochrome oxidase I (COI) gene sequences were analysed to determine the phylogenetic relationship with known bresiliid shrimps. A. longirostris of the Okinawa Trough had two haplotypes of the COI gene, one of which was identical to the Alvinocaris sp. of the cold seeps in Sagami Bay. These results indicate that a long-distance dispersal of A. longirostris occurred possibly within the last 100?000 years.

Tokuda, Gaku; Yamada, Akinori; Nakano, Kazuma; Arita, Nao; Yamasaki, Hideo

2005-01-01

81

Organic Complexing in Smectite Clay Minerals Under Hydrothermal Vent Conditions  

NASA Astrophysics Data System (ADS)

A hydrothermal vent at the Juan de Fuca ridge was found to contain smectite-rich clay minerals. At vent fluid temperatures (300-350°C) smectite quickly reacts to form more stable minerals, such as illite or chlorite, by incorporating metal cations. While similar investigations have assigned the catalytic properties of clays strictly to the surfaces, it is our hypothesis that organic molecules are polymerized in the smectite interlayers during reaction. Upon incorporation of metal cations and primary organic molecules in the expandable interlayer of these clays, gradual changes in the electrochemical environment may catalyze bio-oligomers that are essential components of life. For comparison, we have examined both dioctahedral (montmorillonite; SWy-1) and trioctahedral (saponite) smectite clay minerals which react to illite and chlorite, respectively. An illite standard (IMt-1) has also been examined as a catalyst. Progressive steps in the reaction process have been monitored through hydrothermal experimentation simulating seafloor and subseafloor volcanic conditions in welded gold capsules. K-saturated smectite clays were reacted with aqueous 10 M methanol solutions up to six weeks. Reaction progress was monitored weekly. Results suggest that organic complexity increases as a function of mineralogical reaction. While producing some similar complex organic compounds, reactions starting with illite yielded significantly lower product concentrations than those with the smectites, suggesting the expandable interlayers play an important role in catalysis. Organic analyses were performed by GC-MS; clay analyses by x-ray diffraction.

Canfield, B. M.; Williams, L. B.; Holloway, J. R.

2002-12-01

82

Hydromineral regulation in the hydrothermal vent crab Bythograea thermydron.  

PubMed

This study investigates the salinity tolerance and the pattern of osmotic and ionic regulation of Bythograea thermydron Williams, 1980, a brachyuran crab endemic to the deep-sea hydrothermal vent habitat. Salinities of 33 per thousand-35 per thousand were measured in the seawater surrounding the captured specimens. B. thermydron is a marine stenohaline osmoconformer, which tolerates salinities ranging between about 31 per thousand and 42 per thousand. The time of osmotic adaptation after a sudden decrease in external salinity is about 15-24 h, which is relatively short for a brachyuran crab. In the range of tolerable salinities, it exhibits an iso-osmotic regulation, which is not affected by changes in hydrostatic pressure, and an iso-ionic regulation for Na(+) and Cl(-). The hemolymph Ca(2+) concentration is slightly hyper-regulated, K(+) concentration is slightly hyper-hypo-regulated, and Mg(2+) concentration is strongly hypo-regulated. These findings probably reflect a high permeability of the teguments to water and ions. In addition to limited information about salinity around hydrothermal vents, these results lead to the hypothesis that B. thermydron lives in a habitat of stable seawater salinity. The osmoconformity of this species is briefly discussed in relation to its potential phylogeny. PMID:11687388

Martinez, A S; Toullec, J Y; Shillito, B; Charmantier-Daures, M; Charmantier, G

2001-10-01

83

Hg bioaccumulation in marine copepods around hydrothermal vents and the adjacent marine environment in northeastern Taiwan.  

PubMed

The Hg concentration in seawater and copepod samples collected from the area around hydrothermal vents at Kueishan Island and the adjacent marine environment in northeastern Taiwan were analyzed to study Hg bioaccumulation in copepods living in polluted and clean marine environments. The seawater collected from the hydrothermal vent area had an extremely high concentration of dissolved Hg, 50.6-256 ng l(-1). There was slightly higher Hg content in the copepods, 0.08-0.88 ?g g(-1). The dissolved Hg concentration in the hydrothermal vent seawater was two to three orders of magnitude higher than that in the adjacent environment. The bioconcentration factor of the studied copepods ranged within 10(3)-10(6), and showed higher dissolved concentration as the bioconcentration factor was lower. A substantial abundance, but with less copepod diversity was recorded in the seawater around the hydrothermal vent area. Temora turbinata was the species of opportunity under the hydrothermal vent influence. PMID:23932475

Hsiao, Shih-Hui; Fang, Tien-Hsi

2013-08-06

84

Tubeworm-associated communities at hydrothermal vents on the Juan de Fuca Ridge, northeast Pacific  

Microsoft Academic Search

Hydrothermal vent communities on a mid-ocean ridge crest can be separated by large distances on separate segments. Heat sources, vent character, fluid chemistry and current patterns may differ markedly. This study examines whether vent community characteristics on three of the four southern segments of the Juan de Fuca Ridge are significantly different. Taxonomic composition and relative abundance of the fauna

Maia Tsurumi; Verena Tunnicliffe

2003-01-01

85

Biological nitrogen fixation in the subseafloor associated with mid-ocean-ridge hydrothermal vent systems  

NASA Astrophysics Data System (ADS)

Thermophilic and hyperthermophilic microorganisms that have been isolated from diffuse hydrothermal vent fluid are assumed to reside within hot, anaerobic zones in the subseafloor. These microorganisms can be metabolically versatile or highly specialized, and utilize a variety of carbon and energy sources that are available in hydrothermal vent fluid. However, the nitrogen sources that support subseafloor microbial communities remain unknown. Chemical analyses indicate that nitrate and nitrite are depleted in diffuse hydrothermal vent fluids relative to deep seawater and are absent in reduced fluids above 30°C. Ammonium concentrations in low temperature vent fluid are similar to the low concentrations in deep seawater, with the exception of sedimented hydrothermal vent systems such as Guaymas Basin and the aberrant, unsedimented Endeavour Segment on the Juan de Fuca Ridge. The largest reservoir of nitrogen in the ocean is dissolved dinitrogen gas, which is abundant in deep seawater and slightly elevated in hydrothermal fluids. Biological nitrogen fixation was first suggested as a potential source of nitrogen to hydrothermal vent ecosystems based on the nitrogen isotope ratios of low trophic level vent fauna, which are much lower than the nitrogen isotope ratios of deep sea organic nitrogen, ammonium and nitrate, but resemble those of deep-ocean dinitrogen gas and marine biota associated with nitrogen fixation. We have detected the genetic potential for nitrogen fixation by amplifying and sequencing one of the genes responsible for nitrogen fixation, nifH, from diffuse hydrothermal vent fluid. The nifH genes present in hydrothermal vent fluid originate from a diverse nifH assemblage in the subseafloor as well as a phylogenetically distinct nifH cluster in deep seawater. While there was no major difference in the nifH populations between nitrogen-rich and nitrogen-poor diffuse hydrothermal vents, we will attempt to detect the expression of nifH in situ and in nitrogen-fixing isolates cultured from vent fluids.

Mehta, M.; Butterfield, D. A.; Baross, J. A.

2002-12-01

86

Biogeographic relationships among deep-sea hydrothermal vent faunas at global scale  

Microsoft Academic Search

The discovery of deep-sea hydrothermal vent fauna, kilometres deep in the oceans, is a great achievement of 20th-century marine biology. The deep-sea hydrothermal food web does not directly depend on the sun's energy. Vent communities rely primarily on trophic associations between chemoautotrophic bacteria and consumers. A small number of endemic taxa are adapted to the inhospitable vent environments that are

C. Bachraty; P. Legendre; D. Desbruyères

2009-01-01

87

Mineralization of major lateral teeth in the radula of a deep-sea hydrothermal vent limpet (Gastropoda:Neolepetopsidae)  

Microsoft Academic Search

Radular teeth of a neolepetopsid patellogastropod limpet, Paralepetopsis ferrugivora, from a deep-sea hydrothermal vent site have similar elemental composition (O, Si, P, S, Cl, K and Fe) to radular teeth of the shallow-waters patellogastropod limpets. However, in contrast to shallow waters limpets, the fully mature teeth of P. ferrugivora do not show any crystalline phases. Amorphous silica was found in

R. Cruz; M. Farina

2005-01-01

88

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

NASA Astrophysics Data System (ADS)

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.

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

2003-12-01

89

Simulated Mars Rover Mission to Hydrothermal Vents, Ka'u Desert, Hawai'i  

NASA Astrophysics Data System (ADS)

Observations and measurements were made in the field and samples returned for laboratory study from the Ka'u Desert, Hawai'i. The site includes recent lava flows and flanking older flows, wind-blown and variably altered ash deposits, and alteration associated with sulfurous volcanic vents. The site is an analogue for the type being proposed for the NASA Mars Mobile Geobiology Explorer Mission. Experiments and observations included tripod-based color stereo imaging, thermal imaging, and reflectance spectrometry to map topography, thermal properties, and mineralogy associated with flow and ash-deposit alteration stages and hydrothermal deposits. Laboratory analyses include mineralogy, elemental compositions, and biological analysis of returned samples for ground truth and for comparison to what can be learned from field observations. Integrated studies include comparison of VIS-IR spectra obtained on the ground and observed lithologic endmembers to remotely sensed data and spectral endmembers (Deal et al., this Conf.), development of a topographic model from stereo imaging, alteration of basalts and relationships between ash deposits and basalts, including formation of duricrusts, thermal imaging and development of a thermal model, and characterization of extant and fossilized biological activity associated with sulfurous hydrothermal vents. Analyses to examine active biology at the hydrothermal vents include DNA amplification and identification using PCR (polymerase chain reaction) methods and FISH (fluorescence in-situ hybridization). Morphological evidence of entombment of microbes will be sought in mineralized crusts associated with the hydrothermal deposits. Video documentation of field work coupled with results of field observations and laboratory analyses will be used to better understand and define the essential measurements to make during future Mars missions, with implications for procedures and protocols for eventual sample returns.

Jolliff, B. L.; Arvidson, R. E.; Doty, A. M.; Davies, N.; de St. Maurice, A.; Griggs, L. E.; Gross, M. E.; Ishida, C. C.; Izsak, G. M.; Deal, K. S.; Snider, N. O.

2002-12-01

90

The spatial scale of genetic subdivision in populations of Ifremeria nautilei, a hydrothermal-vent gastropod from the southwest Pacific  

PubMed Central

Background Deep-sea hydrothermal vents provide patchy, ephemeral habitats for specialized communities of animals that depend on chemoautotrophic primary production. Unlike eastern Pacific hydrothermal vents, where population structure has been studied at large (thousands of kilometres) and small (hundreds of meters) spatial scales, population structure of western Pacific vents has received limited attention. This study addresses the scale at which genetic differentiation occurs among populations of a western Pacific vent-restricted gastropod, Ifremeria nautilei. Results We used mitochondrial and DNA microsatellite markers to infer patterns of gene flow and population subdivision. A nested sampling strategy was employed to compare genetic diversity in discrete patches of Ifremeria nautilei separated by a few meters within a single vent field to distances as great as several thousand kilometres between back-arc basins that encompass the known range of the species. No genetic subdivisions were detected among patches, mounds, or sites within Manus Basin. Although I. nautilei from Lau and North Fiji Basins (~1000 km apart) also exhibited no evidence for genetic subdivision, these populations were genetically distinct from the Manus Basin population. Conclusions An unknown process that restricts contemporary gene flow isolates the Manus Basin population of Ifremeria nautilei from widespread populations that occupy the North Fiji and Lau Basins. A robust understanding of the genetic structure of hydrothermal vent populations at multiple spatial scales defines natural conservation units and can help minimize loss of genetic diversity in situations where human activities are proposed and managed.

2011-01-01

91

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

PubMed

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. PMID:18166212

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

2007-12-31

92

Diversity and distributional patterns of ciliates in guaymas basin hydrothermal vent sediments.  

PubMed

Little is known about protists at deep-sea hydrothermal vents. The vent sites at Guaymas Basin in the Gulf of California are characterized by dense mats of filamentous pigmented or nonpigmented Beggiatoa that serve as markers of subsurface thermochemical gradients. We constructed 18S rRNA libraries to investigate ciliate assemblages in Beggiatoa mats and from bare sediments at the Guaymas vent site. Results indicated a high diversity of ciliates, with 156 operational taxonomic units identified in 548 sequences. Comparison between mat environments demonstrated that ciliate and bacterial assemblages from pigmented mats, nonpigmented mats, and bare sediments were significantly different and highly correlated with bacterial assemblages. Neither bacterial nor ciliate assemblages were correlated with environmental factors. The most abundant ciliates at Guaymas were more likely to be represented in clone libraries from other hydrothermal, deep-sea, and/or anoxic or microaerophilic environments, supporting the hypothesis that these ciliate species are broadly distributed. The orange mat environment included a higher proportion of ciliate sequences that were more similar to those from other environmental studies than to cultured ciliate species, whereas clone libraries from bare sediments included sequences that were the most highly divergent from all other sequences and may represent species that are endemic to Guaymas. PMID:23750565

Coyne, Kathryn J; Countway, Peter D; Pilditch, Conrad A; Lee, Charles K; Caron, David A; Cary, Stephen C

2013-06-11

93

Sustained volcanically-hosted venting at ultraslow ridges: Piccard Hydrothermal Field, Mid-Cayman Rise  

NASA Astrophysics Data System (ADS)

At slow spreading mid-ocean ridges sustained submarine venting and the deposition of large seafloor massive sulfide deposits have previously been ascribed to tectonically-controlled hydrothermal circulation unrelated to young volcanic activity. Here, by contrast, we show that the Piccard Hydrothermal Field (PHF), on the ultraslow spreading Mid-Cayman Rise, represents a site of sustained fluid flow and sulfide formation hosted in a neovolcanic setting. The lateral extent and apparent longevity associated with the PHF are comparable to some of the largest tectonically-hosted vent sites known along the slow-spreading Mid-Atlantic Ridge. If such systems recur along all ultraslow ridges, which comprise ˜20% of the ˜55,000 km global ridge crest, potential implications would include (i) a higher probability of locating large, economically valuable, mineral deposits along ultraslow ridges together with (ii) larger fluxes than previously anticipated of chemicals released from high-temperature venting entering the oceans along the Atlantic-Indian Ocean sectors of the deep-ocean thermohaline conveyor.

Kinsey, James C.; German, Christopher R.

2013-10-01

94

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

PubMed Central

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.

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

2000-01-01

95

Hydrothermal vent community zonation along environmental gradients at the Lau back-arc spreading center  

NASA Astrophysics Data System (ADS)

The Lau back-arc spreading center exhibits gradients in hydrothermal vent habitat characteristics from north to south. Biological zonation within a few meters of vents has been described as temperature driven. We constructed georeferenced photomosaics of the seafloor out to tens of meters beyond vents to describe peripheral zonation and explore correlations between environmental conditions and the biological community. Cluster analysis separated northern sites from southern sites, corresponding to a break in substrate from basalt in the north to andesite in the south. Northern sites were dominated by anemones, and southern by sponges. A previous suggestion that dominants may be dependent on friability of the substrate was not supported; when visually distinguishable, individual species within taxa showed different patterns. Northern sites hosted proportionally more suspension feeding species. Sulfide that can support microbial food sources is at higher concentrations at these sites, though bathymetry that may enhance bottom currents is less rugged. Northern sites had higher diversity that may result from the overall northwards flow, which would generally permit easier dispersal downcurrent, though we observed no difference in dispersal strategies at different sites.

Kim, Stacy; Hammerstrom, Kamille

2012-04-01

96

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

SciTech Connect

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 1600-1750 m) and the ultramafic-hosted Rainbow (36 13'N, 33 54.1'W, depth 2270-2330 m) 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.

Flores, Gilberto E [Portland State University; Campbell, James H [ORNL; Kirshtein, Julie D [United States Geological Survey, Reston, VA; Meneghin, Jennifer [Portland State University; Podar, Mircea [ORNL; Steinberg, Joshua [Oregon Episcopal School, Portland, OR; Seewald, Jeffrey S [Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA; Tivey, Margaret Kingston [Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA; Voytek, Mary A [United States Geological Survey & National Aeronautics and Space Administration; Reysenbach, Anna-Louise [Portland State University; Yang, Zamin Koo [ORNL

2011-01-01

97

Phylogenetic diversity and functional gene patterns of sulfur-oxidizing subseafloor Epsilonproteobacteria in diffuse hydrothermal vent fluids  

PubMed Central

Microorganisms throughout the dark ocean use reduced sulfur compounds for chemolithoautotrophy. In many deep-sea hydrothermal vents, sulfide oxidation is quantitatively the most important chemical energy source for microbial metabolism both at and beneath the seafloor. In this study, the presence and activity of vent endemic Epsilonproteobacteria was examined in six low-temperature diffuse vents over a range of geochemical gradients from Axial Seamount, a deep-sea volcano in the Northeast Pacific. PCR primers were developed and applied to target the sulfur oxidation soxB gene of Epsilonproteobacteria. soxB genes belonging to the genera Sulfurimonas and Sulfurovum are both present and expressed at most diffuse vent sites, but not in background seawater. Although Sulfurovum-like soxB genes were detected in all fluid samples, the RNA profiles were nearly identical among the vents and suggest that Sulfurimonas-like species are the primary Epsilonproteobacteria responsible for actively oxidizing sulfur via the Sox pathway at each vent. Community patterns of subseafloor Epsilonproteobacteria 16S rRNA genes were best matched to methane concentrations in vent fluids, as well as individual vent locations, indicating that both geochemistry and geographical isolation play a role in structuring subseafloor microbial populations. The data show that in the subseafloor at Axial Seamount, Epsilonproteobacteria are expressing the soxB gene and that microbial patterns in community distribution are linked to both vent location and chemistry.

Akerman, Nancy H.; Butterfield, David A.; Huber, Julie A.

2013-01-01

98

Denitrification in diffuse hydrothermal vent fluids of Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

Denitrification is a major and well-investigated sink of bio-available nitrogen (N) in the ocean. However, little is known about the removal of N in diffuse hydrothermal vents. Hydrothermal vent fluids are known to harbor diverse bacterial populations, and the use of nitrate as an electron acceptor for the microbially mediated oxidation of hydrogen sulphide has previously been documented in these extreme environments, but no direct measurements of denitrification rates have been reported. We present the first denitrification rate estimates (i.e. the conversion of nitrate to nitrogen gas) derived from 15N-label incubations at 7 diffuse hydrothermal vent sites along the Juan de Fuca Ridge (North-East Pacific). Incubation samples (in-situ temperatures between 6.8 and 40.8?C) were collected during research cruises in June and August 2008. We also measured the isotopic composition of nitrate and ammonium from low-T sites collected during several cruises from 2006 to 2009. Mixing between ambient seawater and sub-seafloor hydrothermal reservoirs is the dominant process that modulates DIN concentration and isotope dynamics. However, clear signs of isotope fractionation of the N (and O of nitrate) isotopes at some sites suggests the presence of nitrate consuming processes, likely denitrification and/or the assimilation by vent microorganisms. 15N incubation-based denitrification rates ranged from 0 to 0.6 ?M N/day, with no consistent relationship with the in-situ temperature of the vent fluids. With only one exception, detectable denitrification rates were determined at all sites, suggesting that denitrification is an important N-elimination process in diffuse vent fluids. Ongoing work that aims at studying the environmental factors that potentially control rates of denitrification (e.g. temperature, flow rate, fluid chemistry), as well as other possible N removal pathways (e.g. anammox and DNRA coupled to anammox), will also be discussed.

Bourbonnais, A.; Lehmann, M. F.; Butterfield, D. A.; Devol, A.; Chang, B. X.; Juniper, K.

2009-12-01

99

In Situ Observations of Dissolved Manganese in Hydrothermal Vent Plumes at Mariana Trough.  

NASA Astrophysics Data System (ADS)

We studied for hydrothermal plumes in Mariana Trough by using in situ Mn-Fe analyzers (GAMOS-II). GAMOS-II (Geochemical Anomalies MOnitoring system) is an in-situ chemical analyzer used to detect manganese and/or iron anomalies in neutrally buoyant plumes and to map distributions in bottom seawater over vent fields. During TN167 (ROV ROPOS / R/V Thomas G Thompson) cruise, GAMOS-II measurements were conducted for plume observation at the Yamanaka and Fryer sites. GAMOS-II was attached on the sampling stage of the ROPOS at dive #'777. ROPOS arrived at the bottom at 0:50, and left the bottom at 10:55. Active manganese and temperature anomalies were detected around 2:00 - 5:00 and 7:00 - 11:00, when the ROPOS passed through hydrothermally active areas. The anomaly of temperature and manganese concentration was observed coincidentally, but the relation ship is not consistently proportional. Wide variation in Mn vs. temperature ratio implies diversity between geochemical flux and heat flux depending on the type of venting in the hydrothermal sites. During KH-04-02 Leg2 (AUV r2D4 / R/V Hakuho-Maru) cruise, GAMOS-II measurements were also conducted for plume observation at NW ROTA #1 seamount. GAMOS-II was attached in the AUV r2D4 with CTD. During four successive dives, the fine structure of hydrothermal plumes changed drastically, probably reflecting temporal variation of hydrothermal activity. Continuous sampling by using GAMOS-II was also done successfully. We will also discuss about the data of this continuous sampling.

Okamura, K.; Yanai, K.; Sohrin, Y.; Ishibashi, J.; Watanabe, M.; Ura, T.

2004-12-01

100

Benthic eukaryotic diversity in the Guaymas Basin hydrothermal vent environment  

PubMed Central

Molecular microbial ecology studies have revealed remarkable prokaryotic diversity in extreme hydrothermal marine environments. There are no comparable reports of culture-independent surveys of eukaryotic life in warm, anoxic marine sediments. By using sequence comparisons of PCR-amplified small subunit ribosomal RNAs, we characterized eukaryotic diversity in hydrothermal vent environments of Guaymas Basin in the Gulf of California. Many sequences from these anoxic sediments and the overlaying seawater represent previously uncharacterized protists, including early branching eukaryotic lineages or extended diversity within described taxa. At least two mechanisms, with overlapping consequences, account for the eukaryotic community structure of this environment. The adaptation to anoxic environments is evidenced by specific affinity of environmental sequences to aerotolerant anaerobic species in molecular trees. This pattern is superimposed against a background of widely distributed aerophilic and aerotolerant protists, some of which may migrate into and survive in the sediment whereas others (e.g., phototrophs) are simply deposited by sedimentary processes. In contrast, bacterial populations in these sediments are primarily characteristic of anoxic, reduced, hydrocarbon-rich sedimentary habitats.

Edgcomb, Virginia P.; Kysela, David T.; Teske, Andreas; de Vera Gomez, Alvin; Sogin, Mitchell L.

2002-01-01

101

Cruise explores hydrothermal vents of the Manus Basin  

NASA Astrophysics Data System (ADS)

A joint Japanese-French program (New STARMER) sampled active hydrothermal sites near the New Britain active subduction zone in the South Pacific from October 16 to November 13, 1995. Using the R/V Yokosuka and the submersible Shinkai 6500, researchers made a number of surprising findings about magmatic, tectonic, and hydrothermal activity at the central and northeastern ridges of the Manus Basin spreading system. Fifteen dives by the submersible revealed a spectrum of hydrothermal processes, ranging from shimmering waters to black smokers. For the first time, highly acidic fluids rich in H2S and low in temperature (87-118°C) were sampled in the eastern part of the Manus Basin.

Scientific Party; Auzende, Jean-Marie; Urabe, Tetsuro

102

Correlations Between Hydrothermal Venting and Axial Magma Chamber Characteristics  

NASA Astrophysics Data System (ADS)

The principal power sources for high-temperature hydrothermal venting have long been thought to be heat mined from solidified magma ("hot rock"), as by a propagating cracking front, and heat supplied conductively from an unsolidified magma body ("axial magma chamber"). However, nearly all high-temperature vents have been found at, or near, locations where seismic studies have imaged an AMC. This association seems especially true on fast-spreading ridges, where lengthy seismic transects have been conducted on several ridge sections. To test the robustness of this association, I here review data from all six multi-segment ridge sections, ranging from 170- 560 km in length, where detailed surveys of both the AMC and hydrothermal plumes have been conducted. The sections include the southern East Pacific Rise (14°-18° S) (560 km), Galapagos Spreading Center (380 km), Juan de Fuca Ridge (365 km), Valu Fa/Eastern Lau Spreading Center (360 km), northern EPR (9° - 12° N) (307 km), and northern EPR (15.3° -16.8° N) (170 km). These sections include a total of 21 2nd or 3rd order tectonic segments. At the section scale, there is no significant correlation (r2 = 0.05) for a least-squares fit between percent AMC coverage and percent plume coverage (ph). Removing the hotspot-affected GSC, however, increases r2 to 0.61. This finding is consistent with evidence showing that hydrothermal activity on hotspot-affected ridges is markedly less than normal ridges of similar spreading rate. The correlation between mean AMC depth below the seafloor and ph for all six sections is high (r2 = 0.58), and improves to r2 = 0.87 if the Valu Fa/ELSC section is excluded. The AMC is unusually deep and the crustal structure along this section is unique along among midocean ridges, perhaps because of its proximity (40-100 km) to the Kermadec volcanic arc. At the individual segment scale, the same correlations are much less robust. AMC coverage vs. ph decreases to r2 = 0.15 whether or not the Galapagos data are included. AMC depth vs. ph decreases to r2 = 0.3 whether or not the Valu Fa/ELSC data are included. This analysis demonstrates that the correlation between the spatial density of venting and the spatial extent or depth of an AMC is weak on the small segment scale but significant at the multi-segment scale. This pattern is the same as found between ph and spreading rate on the small and multi-segment segment scales. In contrast, at both scales venting is more sensitive to AMC depth than AMC extent, a correlation likely linked to the observation that the AMC shallows as spreading rate increases. It may be that ph increases with spreading rate not simply because of a higher magma budget, but also because heat extraction becomes more efficient as AMC depth decreases.

Baker, E. T.

2004-12-01

103

Correlations Between Hydrothermal Venting and Axial Magma Chamber Characteristics  

NASA Astrophysics Data System (ADS)

The principal power sources for high-temperature hydrothermal venting have long been thought to be heat mined from solidified magma ("hot rock"), as by a propagating cracking front, and heat supplied conductively from an unsolidified magma body ("axial magma chamber"). However, nearly all high-temperature vents have been found at, or near, locations where seismic studies have imaged an AMC. This association seems especially true on fast-spreading ridges, where lengthy seismic transects have been conducted on several ridge sections. To test the robustness of this association, I here review data from all six multi-segment ridge sections, ranging from 170- 560 km in length, where detailed surveys of both the AMC and hydrothermal plumes have been conducted. The sections include the southern East Pacific Rise (14°-18° S) (560 km), Galapagos Spreading Center (380 km), Juan de Fuca Ridge (365 km), Valu Fa/Eastern Lau Spreading Center (360 km), northern EPR (9° - 12° N) (307 km), and northern EPR (15.3° -16.8° N) (170 km). These sections include a total of 21 2nd or 3rd order tectonic segments. At the section scale, there is no significant correlation (r2 = 0.05) for a least-squares fit between percent AMC coverage and percent plume coverage (ph). Removing the hotspot-affected GSC, however, increases r2 to 0.61. This finding is consistent with evidence showing that hydrothermal activity on hotspot-affected ridges is markedly less than normal ridges of similar spreading rate. The correlation between mean AMC depth below the seafloor and ph for all six sections is high (r2 = 0.58), and improves to r2 = 0.87 if the Valu Fa/ELSC section is excluded. The AMC is unusually deep and the crustal structure along this section is unique along among midocean ridges, perhaps because of its proximity (40-100 km) to the Kermadec volcanic arc. At the individual segment scale, the same correlations are much less robust. AMC coverage vs. ph decreases to r2 = 0.15 whether or not the Galapagos data are included. AMC depth vs. ph decreases to r2 = 0.3 whether or not the Valu Fa/ELSC data are included. This analysis demonstrates that the correlation between the spatial density of venting and the spatial extent or depth of an AMC is weak on the small segment scale but significant at the multi-segment scale. This pattern is the same as found between ph and spreading rate on the small and multi-segment segment scales. In contrast, at both scales venting is more sensitive to AMC depth than AMC extent, a correlation likely linked to the observation that the AMC shallows as spreading rate increases. It may be that ph increases with spreading rate not simply because of a higher magma budget, but also because heat extraction becomes more efficient as AMC depth decreases.

Baker, E. T.

2007-12-01

104

Continuous Monitoring of Hydrothermal Vent Chemistry: A Window to Subseafloor Processes  

NASA Astrophysics Data System (ADS)

Hydrothermal circulation through mid-ocean ridges are driven by episodic intrusions of basaltic magma. These intrusions change paths for fluid circulation on scales of hours to more than decades. These changes in plumbing ultimately affect the chemical and thermal composition of hydrothermal fluids. Similarly, changes in effluent chemistry are expected as a result of periodic variability in oceanic conditions resulting in differing degrees of dilution with seawater and the potential for further water-rock reactions at low temperatures. Thus, changes in effluent chemistry provide a unique window to processes affecting seawater circulation through oceanic crust. Continuous water samplers (OsmoSamplers) with self contained temperature recorders provide a reliable tool to monitor the concentration of dissolved gases and the major, minor, and trace elements in and temperature of hydrothermal effluent. Samplers have been deployed for several days to more than 3 years in several vents at the Main Endeavour Field (MEF) and Axial Seamount. High resolution samplers deployed for 5-10 days at both sites provide hourly aliquots from which we document the effects of changes in bottom currents (3-day, daily, and tidal) on the extent of subsurface and near surface mixing of hydrothermal and bottom seawater. Longer deployments (1 year) document a variety of changes. At Axial Seamount we observed the gradual and sudden extinction of venting and the gradual decrease in subsurface mixing with unaltered bottom seawater. These results are being synthesized with thermal and hydroacoustic data to match chemical changes with physical processes. In contrast, samplers deployed at MEF for two months display a remarkable consistency in composition. Coupled with flow meters, large volume fluid samplers, and seismometers, OsmoSamplers are valuable tools in discerning processes that control hydrothermal circulation in this dynamic environment.

Wheat, C. G.; Jannasch, H.; Plant, J.; Butterfield, D.; Lupton, J.; Moyer, C.; Tivey, M.; Embley, R.

2001-12-01

105

Hydrothermal Vent Complexes and the Search for ExtraTerrestrial Water  

Microsoft Academic Search

Hydrothermal vent complexes, as have been recently identified on Earth, may also exist on Mars, and could provide important information as to the history of water on that planet. We suggest that some martian craters could be eruptive complex craters.

H. Svensen; G. Gisler; S. Polteau; A. Mazzini; S. Planke

2007-01-01

106

Application of acoustic noise and self-potential localization techniques to a buried hydrothermal vent (Waimangu Old Geyser site, New Zealand)  

NASA Astrophysics Data System (ADS)

A seismo-acoustic and self-potential survey has been performed in the hydrothermal area of the old Waimangu Geyser (New Zealand), which was violently erupting a century ago. Nowadays, no surface activity is visible there. We set-up an array of 16 geophones and recorded a high and steady acoustic ambient noise. We applied the matched field processing (MFP) approach to the acoustic data to locate the sources responsible for the ambient noise. The white noise constraint processor reveals the presence of a unique and well-focused acoustic source at a depth of 1.5 m below the seismic array. For this very shallow source, the application of MFP enabled the determination of both the source location and the dispersion curve of seismic velocity. The study was completed by self-potential (SP) measurements on several profiles around the acoustic noise source, which displayed a large positive anomaly above it. The results of the SP inversion gave an electric streaming current density source very close to the acoustic one. Both sources likely belong to a shallow hydrothermal structure interpreted as a small convective cell of boiling water beneath an impermeable layer. The joint application of these methods is a promising technique to recognize hydrothermal structures and to study their dynamics.

Vandemeulebrouck, J.; Roux, P.; Gouédard, P.; Legaz, A.; Revil, A.; Hurst, A. W.; Bolève, A.; Jardani, A.

2010-02-01

107

Genetic Diversity of Archaea in Deep-Sea Hydrothermal Vent Environments  

Microsoft Academic Search

Molecular phylogenetic analysis of naturally occurring archaeal communities in deep-sea hydrothermal vent environments was carried out by PCR-mediated small subunit rRNA gene (SSU rDNA) sequencing. As determined through partial sequencing of rDNA clones amplified with archaea-specific primers, the archaeal populations in deep-sea hydrothermal vent environments showed a great genetic diversity, and most members of these populations appeared to be uncultivated

Ken Takai; Koki Horikoshi

108

Enigmatic Archaeal and Eukaryotic Life at Hydrothermal Vents and in Marine Subsurface Sediments  

Microsoft Academic Search

This chapter is intended as a brief introduction on specific, novel aspects of archaeal and eukaryotic biodiversity in two\\u000a extreme marine environments, hydrothermal vents and deep subsurface sediments: deeply-branching, uncultured archaea occurring\\u000a in both environments that in some cases do not fit into the well-established crenarchaeota-euryarchaeota dichotomy; the partial\\u000a overlap in the archaeal community structure of hydrothermal vents and deep

Andreas Teske

109

Relationships between lava types, seafloor morphology, and the occurrence of hydrothermal venting in the ASHES vent field of Axial Volcano. [Axial Seamount Hydrothermal Emission Study  

SciTech Connect

Deep-towed and submersible photographic surveys within the caldera of Axial Volcano have been integrated with high-resolution bathmetry to produce a geological map of the most active vent field in the caldera. Locations for over 2,000 photographs in and near the vent field were determined using a seafloor transponder network. Then each photograph was described utilizing a classification system which provides detailed information concerning lava type, hydrothermal activity, sediment cover, geological structure, and biology. Resulting data were entered into a digital data base, and computer-generated maps were created that portray spatial relationships between selected geological variables. In general, the entire ASHES field is characterized by pervasive low-temperature venting. The most vigorous venting is concentrated in an approximately 80 m {times} 80 m area where there are several high-temperature vents including some which are producing high-temperature vapor-phase fluids derived from a boiling hydrothermal system. Lava types within the ASHES vent field are grouped into three distinct morphologies: (1) smooth (flat-surfaced, ropy, and whorled) sheet flows, (2) lobate flows, and (3) jumbled-sheet flows. The most intense hydrothermal venting is concentrated in the smooth sheet flows and the lobate flows. The location of the ASHES field is mainly attributable to faulting which defines the southwest caldera wall, but the concentration of intense venting appears to be related also to the spatial distribution of lava types in the vent field and their contrasting permeabilities. Other structural trends of faults and fissures within the field also influence the location of individual events.

Hammond, S.R. (NOAA, Newport, OR (United States))

1990-08-10

110

Mercury Adaptation among Bacteria from a Deep-Sea Hydrothermal Vent  

Microsoft Academic Search

Since deep-sea hydrothermal vent fluids are enriched with toxic metals, it was hypothesized that (i) the biota in the vicinity of a vent is adapted to life in the presence of toxic metals and (ii) metal toxicity is modulated by the steep physical-chemical gradients that occur when anoxic, hot fluids are mixed with cold oxygenated seawater. We collected bacterial biomass

Costantino Vetriani; Yein S. Chew; Susan M. Miller; Jane Yagi; Jonna Coombs; Richard A. Lutz; Tamar Barkay

2005-01-01

111

Metazoans in Extreme Environments: Adaptations of Hydrothermal Vent and Hydrocarbon Seep Fauna  

Microsoft Academic Search

Some of the most extreme environments where animals survive are associated with active vents and seeps in the deep sea. In addition to the extreme pressure, low temperatures, and lack of light that characterize the deep sea in general, a variety of other factors that are hostile to most animals prevail in these environments. Hydrothermal vent regions show extremes in

Erin R. McMullin; Derk C. Bergquist; Charles R. Fisher

112

Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea hydrothermal vent environments.  

PubMed

Hydrothermal fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct hydrothermal fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) hydrothermal fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether hydrothermal fluids from ultramafic-hosted or basalt-hosted sites were used. Site-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested hydrothermal fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct hydrothermal vent biotopes. PMID:23647923

Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S

2013-05-06

113

Spatial differences in East scotia ridge hydrothermal vent food webs: influences of chemistry, microbiology and predation on trophodynamics.  

PubMed

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. ?(13)C 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 ?(13)C 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 ?(13)C occurred in Kiwa sp. (-19.0‰ to -10.5‰), similar to that of the epibionts sampled from their ventral setae. Kiwa sp. ?(13)C 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 ?(13)C and ?(34)S 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

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

2013-06-07

114

Middle Valley in perspective: New outlooks from changes in local hydrothermal venting  

NASA Astrophysics Data System (ADS)

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 small hydrothermal field consisting of two isolated chimneys and several diffuse flow sites is located ~800 meters northeast of Hole 857D and has been visited periodically by submersible/ROV since 1999. We will present a synthesis of new and existing data from Middle Valley and place them into the context of recent events at 857D and other potential tectonic or magmatic processes in the region. Recent results from the CORK at 857D have shown apparent seafloor uplift, supported by depth records from the submersible Alvin. The rate of uplift is approximately linear over its duration (2005-2010) and has reduced mean seafloor pressure by ~28 kPa, equivalent to nearly 3 meters of head. Initially, the apparent uplift at 857D did not seem to have any effect on local high-temperature hydrothermal venting; fluid temperature and chemistry had not changed significantly since the two chimneys were first observed and sampled. However, new observations from Middle Valley obtained via recent JASON operations show a distinct change in the temperature and character of venting at this site and bring into question the tectonic and/or magmatic processes affecting the region.

Inderbitzen, K. E.; Becker, K.; Davis, E. E.; Hulme, S.; Wheat, C. G.

2010-12-01

115

Study of Hydrothermal Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico  

NASA Astrophysics Data System (ADS)

A shallow (30 ft) hydrothermal site named ``Cora'' (after the indigenous people thereby) was surveyed and sampled throughout direct observation with SCUBA diving during November 25 to December 4, 2000. A total of 10 dives were conducted in order to obtain representative samples from an 85oC fluid source of approximately 10 cm in diameter. Inherent difficulties to the sampling, such as poor visibility and strong bottom currents were overcome and samples of hydrothermal fluid, gas, rocks, and particulate matter were collected directly from the vent. Water samples and hydrothermal fluid were taken with a homemade 1 l cylindrical bottles of two lines by flushing in from the bottom for about ten minutes until total displacement of the seawater; similar procedure was carried out for gas samples. Particulate matter was collected with 0.4mm polycarbonate membrane filters and preserved in a desiccators at a fridge temperature until analysis onshore. Preliminary description of the rock samples suggest that pyritization is the main mineralisation process. Filters containing hydrothermal particulate matter were surveyed under the scanning electron microscope in order to identify the nature (inorganic and organic), as well as the chemistry of the particles. SEM examination revealed the presence of particles of different kind that suggests high degree of mixing and re-suspension: Planctonic organisms and organic matter appeared to be abundant; 25 micron particles of different carbonate faces and inorganic particles of silicates were also recognized. Distinctive euhedral colloidal grains were identified as the resulting process of precipitation from the solution. Microanalysis of iron and sulfur content of 10 micron particles indicate a very likely sulphide mineral face (greigite); 8 micron cinnabar particles are consistent with the mineralization conditions, observed as well in the inner walls of the vent. Analyses of dissolved and particulate trace metals are still ongoing at labs in New Zealand and Mexico and will be incorporated in a near future.

Ortega-Osorio, A.; Prol-Ledesma, R. M.; Reyes, A. G.; Rubio-Ramos, M. A.; Torres-Vera, M. A.

2001-12-01

116

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data  

Microsoft Academic Search

(1) Two surface magnetic surveys, covering the Lucky Strike hydrothermal area, are merged into a single magnetic anomaly description, which, when inverted in the presence of topography, shows a magnetization low at the segment center, close to the central volcano, in the middle of which is located the hydrothermal vent. To test if this magnetization is in any way connected

J. M. Miranda; J. F. Luis; N. Lourenco; F. M. Santos

2005-01-01

117

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data  

Microsoft Academic Search

Two surface magnetic surveys, covering the Lucky Strike hydrothermal area, are merged into a single magnetic anomaly description, which, when inverted in the presence of topography, shows a magnetization low at the segment center, close to the central volcano, in the middle of which is located the hydrothermal vent. To test if this magnetization is in any way connected with

J. M. Miranda; J. F. Luis; N. Lourenço; F. M. Santos

2005-01-01

118

Sulfide Ameliorates Metal Toxicity for Deep-Sea Hydrothermal Vent Archaea†  

PubMed Central

The chemical stress factors for microbial life at deep-sea hydrothermal vents include high concentrations of heavy metals and sulfide. Three hyperthermophilic vent archaea, the sulfur-reducing heterotrophs Thermococcus fumicolans and Pyrococcus strain GB-D and the chemolithoautotrophic methanogen Methanocaldococcus jannaschii, were tested for survival tolerance to heavy metals (Zn, Co, and Cu) and sulfide. The sulfide addition consistently ameliorated the high toxicity of free metal cations by the formation of dissolved metal-sulfide complexes as well as solid precipitates. Thus, chemical speciation of heavy metals with sulfide allows hydrothermal vent archaea to tolerate otherwise toxic metal concentrations in their natural environment.

Edgcomb, Virginia P.; Molyneaux, Stephen J.; Saito, Mak A.; Lloyd, Karen; Boer, Simone; Wirsen, Carl O.; Atkins, Michael S.; Teske, Andreas

2004-01-01

119

Biotic interactions at hydrothermal vents: Recruitment inhibition by the mussel Bathymodiolus thermophilus  

NASA Astrophysics Data System (ADS)

The structure and dynamics of marine communities are regulated in part by variation in recruitment. As in other ecosystems, recruitment at deep-sea hydrothermal vents is controlled by the interplay of propagule supply and behavior, gradients in physical-chemical conditions, and biotic interactions during pre- and post-settlement periods. Recent research along the East Pacific Rise indicates that inhibition of recently settled larvae by mobile predators (mainly limpets) influences patterns of recruitment and subsequent community succession. We conducted a manipulative experiment at the same sites (˜2510 m water depth) to test whether high-density assemblages of the mussel Bathymodiolus thermophilus also inhibit recruitment. In a preliminary study, recruitment of vent invertebrates within the faunal zone dominated by B. thermophilus was strikingly different at two sites, East Wall and Worm Hole. East Wall had high densities of mussels but very low total recruitment. In contrast, Worm Hole had few mussels but high recruitment. Using the submersible Alvin, we transplanted a large number of mussels from East Wall to Worm Hole and quantified recruitment on basalt blocks placed in three treatments: (1) naturally high densities of mussels at East Wall; (2) naturally low densities of mussels at Worm Hole; and (3) high densities of transplanted mussels at Worm Hole. After 11 months, a total of 24 taxa had recruited to the basalt blocks. Recruitment was 44-60% lower in the transplanted high-density mussel patch at Worm Hole and the natural high-density patch at East Wall than within the natural low-density patch at Worm Hole. Biotic processes that may have caused the pattern of recruitment observed included predation of larvae via water filtration by mussels, larval avoidance of superior competitors, interference competition, and enhanced predation by species within the mussel-bed community. Our results indicate that biotic interactions affecting recruitment must be understood to explain patterns of invertebrate community organization and dynamics at hydrothermal vents.

Lenihan, H. S.; Mills, S. W.; Mullineaux, L. S.; Peterson, C. H.; Fisher, C. R.; Micheli, F.

2008-12-01

120

Novel uncultured Epsilonproteobacteria dominate a ¢lamentous sulphur mat from the131N hydrothermal vent ¢eld, East Paci¢c Rise  

Microsoft Academic Search

Rapid growth of microbial sulphur mats have repeatedly been observed during oceanographic cruises to various deep-sea hydrothermal vent sites. The microorganisms involved in the mat formation have not been phylogenetically characterized, although the production of morphologically similar sulphur filaments by a Arcobacter strain coastal marine has been documented. An in situ collector deployed for 5 days at the 131N deep-sea

Erwan Corre; Marie-Anne Cambon-Bonavita; Yves Fouquet; Christian Jeanthon

2006-01-01

121

VentDB: A Global Online Synthesis Database of Seafloor Hydrothermal Spring Geochemistry  

NASA Astrophysics Data System (ADS)

Chemical data for seafloor hydrothermal springs are fundamental to the study of mid-ocean ridge and seafloor processes, ocean water chemistry, and global geochemical cycles, as well as vent ecosystems and the sub-seafloor biosphere. So far, these data have been accessible only in the scientific literature or in online data catalogs where they are widely dispersed in individual data tables, and are often insufficiently documented for re-use. We have developed VentDB as an online data system for geochemical data for hydrothermal springs that will facilitate access and analysis of these data. VentDB uses the concept and architecture of the popular PetDB database for seafloor igneous and metamorphic rock geochemistry (www.petdb.org) to provide easy and fast access to a global synthesis of seafloor hydrothermal spring geochemical data. The VentDB database contains concentrations of major and trace species, dissolved gases, and radiogenic and isotopic ratios for hydrothermal vents on the seafloor. Further chemical or physical properties of hydrothermal springs can be included in the future if desired. The database comprises both the calculated hydrothermal end-member solution compositions as estimated by extrapolation of the concentrations of individual chemical species to a Mg concentration of zero, and the raw data for hydrothermal solution samples as collected, where available. Data quality is documented by including information for the raw analytical data about the analytical method, precision, and reference material measurements, and quality control parameters for end-member compositions including the lowest Mg measured in any sample, the number of samples and correlation coefficient of the linear regression, and the charge balance for the extrapolated zero-Mg composition. The database also includes information about the sampled locations (geospatial coordinates, vent or vent field names, names of other physiographic features), temperature, flow and vent type, sampling device, and the data source. Users can search VentDB by parameters such as location, tectonic setting, type of vent and flow, sampling device, and research cruise, select any number and combination of chemical species that they are interested in, and retrieve a customized dataset that fully integrates data from any number of publications and other sources. VentDB will be available as a prototype system with a limited dataset in Fall 2011 at http://www.ventdb.org. Data compilation of published data will continue with the goal to provide a comprehensive synthesis in 2012.

Mottl, M. J.; Lehnert, K. A.; Johansson, A. K.; Hsu, L.

2011-12-01

122

Benthopelagic macrozooplankton communities at and near deep-sea hydrothermal vents in the eastern Pacific ocean and the Gulf of California  

NASA Astrophysics Data System (ADS)

Benthopelagic zooplankton communities at hydrothermal vents on the East Pacific Rise and in Guaymas Basin are enriched in terms of both biomass and abundance with respect to non-vent areas, but depleted relative to biomass of surface zooplankton communities. Larval and juvenile stages of many benthic species, including Calyptogena spp., Bathymodiolus thermophilus, Nuculana sp., two undescribed species of limpets, Dahlella caldariensis, Bythograea sp., Munidopsis sp., epicaridean isopods, and lysianassid amphipods, were collected in the water column 1-5 m above vent areas. Since much of the zooplankton community is derived from the benthic community, macrozooplankton abundance and composition differ among vent sites in accordance with the nature and extent of development of the benthic community and depend, ultimately, on the history of hydrothermal activity at each site.

Berg, Carl J.; Van Dover, Cindy Lee

1987-03-01

123

Laser-induced Native Fluorescence Detection of Organic Molecules in Hydrothermal Vent Rocks  

NASA Astrophysics Data System (ADS)

We have developed a Multi-channel Deep Ultraviolet Excitation (McDuve) fluorescence detector that has been deployed at several Pacific hydrothermal vent sites [1]. The in situ McDuve detector was able to detect organic molecules at the vent site on rock surfaces and in the water, the signatures being distinguishable one from the other. The McDuve fluorescence detector uses a 224.3 nm helium-silver hollow cathode laser to induce native fluorescence from a sample. Spectral separation is achieved with optical band-pass filters which are coupled to photomultiplier tubes (PMTs) for detection. Samples were recovered at the vent sites and returned from the expedition for bench-top analysis for correlation of the McDuve observations with standard analytical tools-GCMS and X-ray diffraction (for mineralogical ID), as well as with a bench-top version of the McDuve fluorescence detector. Here we report the corroborative results of the laboratory studies. Several preserved samples were subjected to 224.3 nm ultraviolet excitation under wet and dry conditions. Organic molecules were detected on the wet samples analyzed in the lab, corroborating the in situ McDuve data. The fluorescence emission wavelengths associated with the detected organic molecules suggest they are 3-5 ring polycyclic aromatic hydrocarbons [2,3]. The samples were also pyrolized at 500 ºC to decompose any organic molecules present and subsequently reanalyzed. This McDuve analysis revealed a significant decrease in laser induced native fluorescence, a result consistent with the pyrolytic decomposition of the organic content of the rock samples. [1] Conrad, P.G., A.L. Lane, R. Bhartia, W. Hug, (March 2004) Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents 35th Lunar Plan. Sci. XXXV, 2055. [2] Karcher, W. (1985), Spectral Atlas of Polycyclic Aromatic Compounds, vol. I, Kluwer Academic Publishing Company, Dordrecht, Holland. [3] Bhartia, R., McDonald, G.D., Salas, E.C., Hug, W., Reid, R., Conrad, P.G., (2004) A Model to Differentiate Organic Compounds Based on UV Fluorescence Spectroscopy, Intl. J. Astrobiology, Suppl. 1, 115-116

Harju, E.; Kidd, R. D.; Bhartia, R.; Conrad, P. G.

2004-12-01

124

Larvae from afar colonize deep-sea hydrothermal vents after a catastrophic eruption  

PubMed Central

The planktonic larval stage is a critical component of life history in marine benthic species because it confers the ability to disperse, potentially connecting remote populations and leading to colonization of new sites. Larval-mediated connectivity is particularly intriguing in deep-sea hydrothermal vent communities, where the habitat is patchy, transient, and often separated by tens or hundreds of kilometers. A recent catastrophic eruption at vents near 9°50?N on the East Pacific Rise created a natural clearance experiment and provided an opportunity to study larval supply in the absence of local source populations. Previous field observations have suggested that established vent populations may retain larvae and be largely self-sustaining. If this hypothesis is correct, the removal of local populations should result in a dramatic change in the flux, and possibly species composition, of settling larvae. Fortuitously, monitoring of larval supply and colonization at the site had been established before the eruption and resumed shortly afterward. We detected a striking change in species composition of larvae and colonists after the eruption, most notably the appearance of the gastropod Ctenopelta porifera, an immigrant from possibly more than 300 km away, and the disappearance of a suite of species that formerly had been prominent. This switch demonstrates that larval supply can change markedly after removal of local source populations, enabling recolonization via immigrants from distant sites with different species composition. Population connectivity at this site appears to be temporally variable, depending not only on stochasticity in larval supply, but also on the presence of resident populations.

Mullineaux, Lauren S.; Adams, Diane K.; Mills, Susan W.; Beaulieu, Stace E.

2010-01-01

125

Zinc stable isotopes in seafloor hydrothermal vent fluids and chimneys  

Microsoft Academic Search

Many of the heaviest and lightest natural zinc (Zn) isotope ratios have been discovered in hydrothermal ore deposits. However, the processes responsible for fractionating Zn isotopes in hydrothermal systems are poorly understood. In order to better assess the total range of Zn isotopes in hydrothermal systems and to understand the factors which are responsible for this isotopic fractionation, we have

Seth G. John; Olivier J. Rouxel; Paul R. Craddock; Alison M. Engwall; Edward A. Boyle

2008-01-01

126

Extreme Spatial Variability in Microbial Mat Communities from Submarine Hydrothermal Vents Located at Multiple Volcanoes along the Mariana Island Arc  

NASA Astrophysics Data System (ADS)

Volcanic arc systems are the most active tectonic feature in the world, but are among the least studied. The Western Pacific contains ~20,000 km of volcanic arcs, of which only ~2% have been systematically surveyed. The lack of comprehensive knowledge of volcanic arcs is compounded by the incredible variability found in relatively short distances. The complex source history of hydrothermal fluids and the variable depths of seamounts found in island arc systems result in highly variable vent chemistries and therefore unique microbial habitats within relatively short distances. The Mariana Island Arc was surveyed in 2003 and areas with suspected hydrothermal activities were identified for targeted remote operating vehicle (ROV) exploration and sampling in 2004. Sixteen microbial mat samples from five seamounts ranging from 145-1742 mbsl and from ambient to 222°C were collected and analyzed with quantitative PCR (Q-PCR), cluster analysis of terminal restriction length polymorphism (T-RFLP) community fingerprints, and by clone library analysis of small subunit ribosomal rDNA genes. The microbial mat communities from the Mariana Island Arc exhibit greater spatial variability within their community structure than microbial mats sampled from mid-ocean ridge or hotspot hydrothermal vents from a comparable scale. Microbial communities from the summit of NW Eifuku Volcano are dominated by putative iron-oxidizing phylotypes at the Yellow Top and Yellow Cone Vent sites, but are dominated by sulfur-oxidizing ?-Proteobacteria at the Champagne Vent site. Mats collected at the Mat City Vent site on E Diamante Seamount contained nearly three times as much biomass as any other mat sample collected, and is dominated by a Planctomyces phylotype. Hydrothermal sediments at the Fish Spa site located on Daikoku Seamount contained the second highest biomass detected and supported a large community of flatfish indicating a direct route for biomass being channeled up the food chain. The microbial community at Fish Spa consists of a highly diverse assemblage of Bacteroidetes, ?-Proteobacteria and Firmicutes. While in contrast, the microbial mat at the Iceberg Vent site on NW Rota I is dominated by a single phylotype of ?-Proteobacteria.

Davis, R. E.; Moyer, C. L.

2005-12-01

127

Sulfide Ameliorates Metal Toxicity for Deep-Sea Hydrothermal Vent Archaea  

Microsoft Academic Search

The chemical stress factors for microbial life at deep-sea hydrothermal vents include high concentrations of heavy metals and sulfide. Three hyperthermophilic vent archaea, the sulfur-reducing heterotrophs Thermo- coccus fumicolans and Pyrococcus strain GB-D and the chemolithoautotrophic methanogen Methanocaldococcus jannaschii, were tested for survival tolerance to heavy metals (Zn, Co, and Cu) and sulfide. The sulfide addition consistently ameliorated the high

Virginia P. Edgcomb; Stephen J. Molyneaux; Mak A. Saito; Karen Lloyd; Simone Boer; Carl O. Wirsen; Michael S. Atkins; Andreas Teske

2004-01-01

128

In situ microsensor studies of a shallow water hydrothermal vent at Milos, Greece  

Microsoft Academic Search

The microenvironment and microcirculation of a shallow water hydrothermal vent system was studied together with the benthic primary production at Milos, Greece. In situ microprofiles of O2, pH, H2S and temperature were obtained using a miniaturised version of a profiling instrument. The sediment temperature increased toward the centre of the vent system, reaching a surface maximum of 100°C in the

Frank Wenzhöfer; Ola Holby; Ronnie N Glud; Helle K Nielsen; Jens K Gundersen

2000-01-01

129

Culture-independent characterization of a novel microbial community at a hydrothermal vent at Brothers volcano, Kermadec arc, New Zealand  

NASA Astrophysics Data System (ADS)

The bacterial and archaeal diversity of a hydrothermal vent microbial community at Brothers volcano situated in the Kermadec arc, ˜400 km off the north coast of New Zealand, was examined using culture-independent molecular analysis. An unusual microbial community was detected with only 1% and 40% of the bacterial phylotypes exhibiting >92% small subunit (SSU) rRNA gene sequence similarity with cultivated and noncultivated microbes, respectively. Of the 29 bacterial representative phylotypes, over one third of the SSU rRNA gene sequences retrieved belonged to uncultivated candidate divisions including OP1, OP3, OP5, OP8, OD1, and OP11. All archaeal phylotypes belonged to the phylum Euryarchaeota in the uncultivated groups deep hydrothermal vent euryarchaeotal (DHVE) I and II or to the phylum Korarchaeota. Like the bacterial clone library, only a small proportion of archaeal SSU rRNA gene sequences (˜2% and 20%) displayed >92% sequence identity with any archaeal isolates or noncultivated microbes, respectively. Although the bacterial phylotypes detected were phylogenetically most similar to microbial communities detected in methane, hydrocarbon, and carbon dioxide-based hydrothermal and seep environments, no phylotypes directly associated with anaerobic methane oxidation and mcrA activity could be detected. The geochemical composition of the vent fluids at the Brothers-lower cone sample site is unusual and we suggest that it may play a prominent role in the species selection of this microbial community.

Stott, M. B.; Saito, J. A.; Crowe, M. A.; Dunfield, P. F.; Hou, S.; Nakasone, E.; Daughney, C. J.; Smirnova, A. V.; Mountain, B. W.; Takai, K.; Alam, M.

2008-08-01

130

Rock Magnetic Investigation of Felsic Hydrothermal Vent System: Results from ODP Leg 193 to Eastern Manus Basin, Papua New Guinea  

NASA Astrophysics Data System (ADS)

In November-December, 2000, an active hydrothermal vent field in the Eastern Manus back-arc basin, Papua New Guinea, known as the PACMANUS vent field, was drilled during ODP Leg 193. This vent field has been considered as a modern-day analog of massive volcanogenic sulfide deposits within felsic volcanic sequence. The recovery was generally low due to fragility of rocks. Detailed paleomagnetic and rock magnetic analyses were performed on rock samples recovered from three major sites (Sites 1188, 1189 and 1191). Site 1188, a low-temperature diffused venting region, was drilled to 370 mbsf utilizing a combination of RCB, Hammer Drill, ADCB and casing, and Site 1189, a black smoker region, was drilled to a depth of 200 mbsf using RCB. Paleomagnetic analysis shows that recovered rock samples have inclination close to the present-day Earth field. The top 35 m of PACMANUS vent field consists of fresh to moderately altered dacite-rhyodacite and exhibits moderately high natural remanent magnetization (< 6 A/m). Although there are small intervals of markedly less intensive alteration, the region below this extrusive layer is largely comprised of pervasively altered rocks with little evidence of sulfide deposit and exhibits as a whole a low magnetization intensity. However, two intervals with high remanent magnetization (> 6 A/m) were recognized below the upper extrusive layer at Site 1188 (135-211 mbsf and 280-370 mbsf) and one interval at Site 1189 (137-190 mbsf). In particular, the samples between 135-211-mbsf interval at Site 1188 have extremely high remanence with intensities ranging up to 300-500 A/m. Although pockets of magnetite are not uncommon in the ancient hydrothermal ore bodies, they have seldom been documented in modern-day system, and little is known about the physical and chemical condition that allows the magnetite to form in hydrothermal systems. Two possibilities of magnetite formation and its apparent alignment with the Earth field are explored: one that these magnetites precipitated from magnetite-rich fluid as it cooled from above the Curie temperature (TRM) and the other that magnetization was acquired by the growth of magnetite grains below the Curie temperature (CRM). Understanding the origin and behavior of these magnetic mineral assemblages may in turn provide a valuable constraint on the physical and chemical conditions of subseafloor hydrothermal systems, which are very poorly known at the moment.

Lee, S.

2003-12-01

131

Subtidal gastropods consume sulfur-oxidizing bacteria: evidence from coastal hydrothermal vents  

SciTech Connect

The black abalone (Haliotis cracherodii), a commercially important shallow-water gastropod common off White Point, Southern California, is found frequently at subtidal hydrothermal vents within mats of filamentous sulfur-oxidizing bacteria. Foraging vent abalones actively consume the bacteria and confine their nightly feeding forays to bacterial mats surrounding the vents. The growth of abalones consuming the sulfur bacteria exceeds that of control individuals consuming microalgae and is comparable to reported growth rates of abalones consuming macroalgae. Thus, off White Point, the black abalone may derive a portion of its nutrition from the subsidy of geothermal energy.

Stein, J.L.

1984-02-17

132

Isolated communities of Epsilonproteobacteria in hydrothermal vent fluids of the Mariana Arc seamounts.  

PubMed

Low-temperature hydrothermal vent fluids represent access points to diverse microbial communities living in oceanic crust. This study examined the distribution, relative abundance, and diversity of Epsilonproteobacteria in 14 low-temperature vent fluids from five volcanically active seamounts of the Mariana Arc using a 454 tag sequencing approach. Most vent fluids were enriched in cell concentrations compared with background seawater, and quantitative PCR results indicated that all fluids were dominated by bacteria. Operational taxonomic unit-based statistical tools applied to 454 data show that all vents from the northern end of the Mariana Arc grouped together, to the exclusion of southern arc seamounts, which were as distinct from one another as they were from northern seamounts. Statistical analysis also showed a significant relationship between seamount and individual vent groupings, suggesting that community membership may be linked to geographical isolation and not geochemical parameters. However, while there may be large-scale geographic differences, distance is not the distinguishing factor in the microbial community composition. At the local scale, most vents host a distinct population of Epsilonproteobacteria, regardless of seamount location. This suggests that there may be barriers to exchange and dispersal for these vent endemic microorganisms at hydrothermal seamounts of the Mariana Arc. PMID:20533947

Huber, Julie A; Cantin, Holly V; Huse, Susan M; Welch, David B Mark; Sogin, Mitchell L; Butterfield, David A

2010-05-14

133

Significance of polysaccharides in microbial physiology and the ecology of hydrothermal vent environments  

NASA Astrophysics Data System (ADS)

Hyperthermophilic microorganisms (those with maximum growth temperatures of 90°C and above) are known to inhabit deep-sea hydrothermal vent environments and are suspected of being present in the associated subsurface biosphere. One characteristic of the growth physiology of many heterotrophic hyperthermophiles is the capacity to use complex polysaccharides (e.g., ?- and ?-linked glucans as well as non-glucan hemicellulases) as carbon and energy sources. Polysaccharides may also play an important ecological role in the deep-sea subsurface biosphere as the structural elements of biofilms harboring both heterotrophic and chemolithotrophic microorganisms, representing a range of growth temperatures. Genome sequence analysis of several hyperthermophiles indicates that the enzymatic machinery to synthesize and hydrolyze polysaccharides is present in this group of microorganisms. This is supported by the biochemical characteristics of glycosidases from hyperthermophiles in addition to the observation that several hyperthermophiles form biofilms in pure and co-culture. It remains to be seen if biofilms form the basis for a subsurface biosphere but this possibility seems likely given the physiological characteristics of several hyperthermophiles and mesophiles, representative of microorganisms previously isolated from vent sites.

Pysz, Marybeth A.; Montero, Clemente I.; Chhabra, Swapnil R.; Kelly, Robert M.; Rinker, Kristina D.

134

Heat shock protein expression pattern (HSP70) in the hydrothermal vent mussel Bathymodiolus azoricus.  

PubMed

We previously reported evidence of increased levels of DNA damage in the hydrothermal mussel Bathymodiolus azoricus, which suggested that the species was not fully resistant to the natural toxicity of its deep-sea vent environment. In the present study, HSP70 was used as a biomarker of sub-cellular stress. Differences in HSP70 expression pattern were observed between vent sites, typified by different depths/toxicity profiles, and between different mussel tissue types. A comparison of specimens collected by remote operated vehicle (ROV) and acoustically-operated cages showed that less stress (as indicated by changes in HSP70 levels) was induced by the faster cage recovery method. Therefore alternatives to ROV collection should be considered when planning experiments involving live deep sea organisms. Significantly, a positive correlation was found between the levels of DNA strand breakage, as measured using the Comet assay, and HSP70 expression pattern; evidence was also obtained for the constitutive expression of at least one HSP isoform which was located within the cell nucleus. PMID:17316784

Pruski, A M; Dixon, D R

2007-01-17

135

Host-Symbiont Relationships in Hydrothermal Vent Gastropods of the Genus Alviniconcha from the Southwest Pacific  

PubMed Central

Hydrothermal vent gastropods of the genus Alviniconcha are unique among metazoans in their ability to derive their nutrition from chemoautotrophic ?- and ?-proteobacterial endosymbionts. Although host-symbiont relationships in Alviniconcha gastropods from the Central Indian Ridge in the Indian Ocean and the Mariana Trough in the Western Pacific have been studied extensively, host-symbiont relationships in Alviniconcha gastropods from the Southwest Pacific remain largely unknown. Phylogenetic analysis using mitochondrial cytochrome c oxidase subunit I gene sequences of host gastropods from the Manus, North Fiji, and Lau Back-Arc Basins in the Southwest Pacific has revealed a new host lineage in a Alviniconcha gastropod from the Lau Basin and the occurrence of the host lineage Alviniconcha sp. type 2 in the Manus Basin. Based on 16S rRNA gene sequences of bacterial endosymbionts, two ?-proteobacterial lineages and one ?-proteobacterial lineage were identified in the present study. The carbon isotopic compositions of the biomass and fatty acids of the gastropod tissues suggest that the ?- and ?-proteobacterial endosymbionts mediate the Calvin-Benson cycle and the reductive tricarboxylic acid cycle, respectively, for their chemoautotrophic growth. Coupling of the host and symbiont lineages from the three Southwest Pacific basins revealed that each of the Alviniconcha lineages harbors different bacterial endosymbionts belonging to either the ?- or ?-Proteobacteria. The host specificity exhibited in symbiont selection provides support for the recognition of each of the host lineages as a distinct species. The results from the present study also suggest the possibility that Alviniconcha sp. types 1 and 2 separately inhabit hydrothermal vent sites approximately 120 m apart in the North Fiji Basin and 500 m apart in the Manus Basin.

Suzuki, Yohey; Kojima, Shigeaki; Sasaki, Takenori; Suzuki, Masae; Utsumi, Takashi; Watanabe, Hiromi; Urakawa, Hidetoshi; Tsuchida, Shinji; Nunoura, Takuro; Hirayama, Hisako; Takai, Ken; Nealson, Kenneth H.; Horikoshi, Koki

2006-01-01

136

Hydrothermal Vent Plume Discovery and Survey with an Autonomous Underwater Vehicle  

NASA Astrophysics Data System (ADS)

Autonomous Underwater Vehicles (AUVs) can detect and localize deep sea hydrothermal plumes, and through the use of on-board intelligence have the potential to significantly improve the efficiency of plume search. The Autonomous Benthic Explorer has encountered both previously known and newly discovered hydrothermal vents in a variety of settings, including the East Pacific Rise (9°N and 18°S), the Juan de Fuca Ridge (47° 54'N), several sites along the Galapagos Rift (86°-89°W), and the Explorer Ridge (49° 46'N). Typically, these plumes were encountered during sonar, video, and magnetic survey with the vehicle following the bottom terrain at heights from 6 to 40 meters, which in most cases placed the vehicle in the rising, buoyant portion of the plume. Typical instruments carried aboard the vehicle include CTD and optical backscatter, and ABE has also carried an acoustic current meter and a redox potential sensor. AUVs have great potential for efficiently locating vent sites. Unlike ship-towed CTDs, ROVs or manned submersibles, AUVs are uniquely suited to carrying out systematic, exhaustive search patterns. The addition of on-board intelligence, allowing the vehicle to alter its survey track based on sensor data, can greatly improve the yield from an AUV dive. For example, after detecting a plume, the vehicle could break off from its broad area survey and perform a fine grid, possibly at different heights off bottom. But before we can take advantage of this potential, we must understand how an AUV "sees" a plume, and how that perspective can change for different types of vents in different settings. Our experience with ABE indicates that a successful autonomous plume survey must be based on a detailed understanding of plume physics. The plumes encountered by ABE in these surveys varied widely in terms of the magnitude of their fluid and thermal output, topographic setting, and ambient currents. The AUV-based observations of these plumes also varied widely, and these observations shed considerable light on the use of AUVs to autonomously detect and localize plumes. The Main Endeavor plumes were surveyed at a height of 70 meters off bottom and showed temperature anomalies up to 500 millidegrees, intense optical backscatter signals, and vertical velocities up to 25 cm/s. These velocities were sufficiently strong that they could be measured with a current meter carried on the vehicle or inferred through their effect on the vertical dynamics of the vehicle. At another extreme, at the Galapagos Rift, ABE surveyed a plume (ALR/3791Vent) with temperature anomalies as small as 20 millidegrees, and no optical backscatter signal or discernable vertical velocity at a height of 40 meters. This smaller plume was ground-truthed by observations from the deep submersible Alvin. Finally, ABE surveyed the Calyfield on the Galapagos Rift shortly after its discovery by Alvin and observed little or no anomaly. As Calyfield is certainly more vigorous than the ALR/3791 vent, the lack of a discernable signature while surveying in the same manner that located the ALR/3791vent is noteworthy. This is most likely due to the complex hydrographic setting of the shallower Calyfield environment, including strong and variable tidal currents over abrupt topography and the presence of multiple water masses. These results will be compared to other plume prospecting techniques applied in the Galapagos including classical CTD tow-yo's and a CTD-instrumented towed camera sled.

Yoerger, D. R.; Collier, R.; Bradley, A. M.

2002-12-01

137

New Frontiers in Arctic Exploration: Autonomous Location and Sampling of Hydrothermal Vents Under the Ice at Earth's Slowest Spreading Ridge (IPY Project 173)  

NASA Astrophysics Data System (ADS)

As part of IPY project #173, we are planning an international expedition for 2007 to locate and study hydrothermal vents on the ultraslow-spreading Gakkel Ridge, at depths greater than 4000 m beneath the permanent ice cap. This effort necessitates the development of novel exploration technologies, because the Gakkel Ridge rift valley is inaccessible to traditional deep submergence tools. With funding from NASA, NSF, and the private sector we have developed two new autonomous underwater vehicles that will find and map hydrothermal plumes in the water column, trace the buoyant plume stem to the seafloor source, and then map, photograph, and collect samples from the vent sites. The Gakkel Ridge is a key target for hydrothermal exploration not only because of its spreading rate but also because its geographic and hydrographic isolation from other portions of the mid-ocean ridge system have important implications for novel endemic vent fauna. Our major scientific themes are the geological diversity and biogeography of hydrothermal vents on the Arctic mid-ocean ridge system. Our major technology theme is autonomous exploration and sample return with an explicit mandate to develop techniques and methods for eventual use in astrobiology missions to search for life under the ice covered oceans of Europa, a moon of Jupiter. In addition to the US-led Gakkel Ridge expedition, a Norway-led expedition will target sites in seasonally ice-free water over the Mohns Ridge. The results of these two expeditions will be combined to reveal systematic patterns regarding biogeography (through both community-level and genetic-level investigations) of vent-endemic fauna, to study the differences between basalt vs. peridotite hosted vent fields, and to improve our understanding of hydrothermal circulation at ultra- slow spreading plate boundaries where amagmatic extension and long-lived faulting predominate. The expeditions will provide educational and outreach activities through the award-winning Dive and Discover (www.divediscover.whoi.edu) web site.

Edmonds, H. N.; Reves-Sohn, R.; Singh, H.; Shank, T. M.; Humphris, S.; Seewald, J.; Akin, D.; Bach, W.; Nogi, Y.; Pedersen, R.

2006-12-01

138

Composition and biogeography of hydrothermal vent communities in Western Pacific Back-Arc Basins  

NASA Astrophysics Data System (ADS)

Deep-sea hydrothermal vent communities have been located and studied over different geological and dynamic contexts: fast to slow mid-ocean ridges, back-arc basins, volcanic arcs, and active seamounts. The associated vent faunas belong to a small set of mostly endemic taxa relying on chemoautotrophic microbial production, able to stand extreme habitat conditions and to persist in a discontinuous and ephemeral environment. Because of their obligate relations to hydrothermal venting, they disperse only along ridges, stepping from one active hydrothermal vent to another. Discontinuities of the ridges or hydrological barriers can limit along-axis dispersal and thus favor allopatric speciation. Western Pacific back-arc basins are isolated spreading centers, which remain active during a short period of geological time, in the proximity of active and passive continental margins where cold seeps are frequent. The Rim of Fire region thus represents a complex area of potential exchanges between chemosynthetic-based ecosystems. Our present knowledge is restricted to active areas situated in five back-arc basins (Lau and North Fiji Basins, Manus Basin, Mariana Trough, Okinawa Trough) and two arc volcanoes (Izu-Ogasawara, Kermadec Arc). We here review the distribution and composition of vent-associated biological communities in these basins and arcs, and discuss the faunal affinities among them and the possible migration routes between them and the mid-ocean ridges.

Desbruyères, Daniel; Hashimoto, Jun; Fabri, Marie-Claire

139

Microbial Diversity at a Hot, Shallow-Sea Hydrothermal Vent in the Southern Tyrrhenian Sea (Italy)  

Microsoft Academic Search

Microbial community thriving at shallow hydrothermal vent named Black Point, close to the Island of Panarea in the Southern Tyrrhenian Sea (Italy), was studied by microscopic, cultural and molecular methods. New strains of Bacillus and Geobacillus were isolated. Members of sulphur-oxidizing bacteria, belonging to the genera Halothiobacillus and Thiomicrospira were demonstrated by both culture-dependent and -independent methods. Genetic diversity of

Teresa L. Maugeri; Valeria Lentini; Concetta Gugliandolo; Sylvie Cousin; Erko Stackebrandt

2010-01-01

140

Post-capture investigations of hydrothermal vent macro-invertebrates to study adaptations to extreme environments  

Microsoft Academic Search

Typical survival strategies, developed by macro-invertebrates at a variety of reducing marine habitats including deep-sea hydrothermal vents, have been the subject of the laboratory experimentation over the past three decades. This review provides an insight into the international efforts that have converged on the area of laboratory maintenance of such species whose nutritional requirements are outside the usual scope of

Eniko Kadar; Jonathan J. Powell

2006-01-01

141

A seamless system for the collection and cultivation of extremophiles from deep-ocean hydrothermal vents  

Microsoft Academic Search

Pele's Pit is a 300-m-deep pit crater whose summit rises to a depth of 1000 m on the Loihi submarine volcano 34 km south of the island of Hawaii. Hydrothermal vents with water temperatures up to 198°C have been observed at the basal edge of the pit. We fabricated a \\

Alexander Malahoff; Todd Gregory; Arnaud Bossuyt; Stuart Donachie; M. Alarn

2002-01-01

142

Shallow-water hydrothermal vents in the Mediterranean sea: stepping stones for Lessepsian migration?  

Microsoft Academic Search

The present study was carried out in Palaeochori Bay, south eastern coast of Milos, where outflow of hot gas bubbles and hydrothermal water seepage was observed. The study tests hypotheses about relationships between seawater temperature and species with warm-water affinities in areas close to shallow-water vents. We predicted that if temperature plays a major role in influencing abundance of species

Anna Maria De Biasi; Stefano Aliani

2003-01-01

143

Hydrocarbon seep and hydrothermal vent paleoenvironments and paleontology: Past developments and future research directions  

Microsoft Academic Search

Hydrocarbon seeps and hydrothermal vents are now known to be common at continental margins and oceanic spreading centers worldwide, exuding fluids rich in CH4 and H2S, and teeming with life based on chemosynthesis. These settings have been implicated as the crucibles for life's origin, and as locales for methane release to the atmosphere from hydrate destabilization during past climate change.

Kathleen A. Campbell

2006-01-01

144

A modeling approach of the influence of local hydrodynamic conditions on larval dispersal at hydrothermal vents  

Microsoft Academic Search

Deep-sea hydrothermal vent animal communities along oceanic ridges are both patchy and transient. Larval dispersal is a key factor in understanding how these communities function and are maintained over generations. To date, numerical approaches simulating larval dispersal considered the effect of oceanic currents on larval transportation over hundreds of kilometers but very seldom looked at the effect of local conditions

Marc Bailly-Bechet; Michel Kerszberg; Franc-oise Gaill; Florence Pradillon

2008-01-01

145

Larval abundance and dispersal at deep-sea hydrothermal vents in the southern Mariana Trough  

Microsoft Academic Search

Since the discovery of deep-sea hydrothermal vents over thirty years ago, scientists have been perplexed by the question: ``How are the faunal populations established and maintained at these very discrete and often ephemeral habitats?'' For the animals that are sessile or have limited mobility as adults, dispersal to these habitats occurs early in the life cycle, as planktonic larvae in

S. E. Beaulieu; H. Watanabe; S. W. Mills; F. Pradillon; S. Kojima; L. S. Mullineaux

2010-01-01

146

Genetic heterogeneity among New Zealand species of hydrothermal vent mussels (Mytilidae: Bathymodiolus )  

Microsoft Academic Search

Molecular systematic studies provide evidence for three new species of Bathymodiolus-like hydrothermal vent mussels (Bivalvia: Mytilidae) from relatively shallow waters (depth less than 750 m) associated with the Kermadec Arc off northern New Zealand. Mitochondrial COI sequences from the three putative new species differed substantially from those of other known bathymodiolin species from the Pacific and Indian Oceans. Population genetic analysis

P. J. Smith; S. M. McVeagh; Y. Won; R. C. Vrijenhoek

2004-01-01

147

Recruitment of marine invertebrates to hard substrates at deep-sea hydrothermal vents on the East Pacific Rise and Galapagos spreading center  

NASA Astrophysics Data System (ADS)

Recruitment panels were placed at and near hydrothermal vent communities at three sites on the Galapagos spreading center and one site on the East Pacific Rise at 21°N. Deployment periods ranged from 26 days (Clam Acres, 21°N) to 260-320 days (Rose Garden, Garden of Eden, Mussel Bed, GSC) to 1216 days (Clam Acres). Recruitment of gastropod post-larvae and juveniles was observed on arrays deployed at Clam Acres for 26 days. Regardless of length of deployment, populations of polychaetes, mollusks, and barnacles colonizing the panels were predominantly post-larval, juvenile, or sub-adult stages. We suggest that some combination of competition, migration, and predation maintains these populations in immature stages. Size distributions of individuals within a taxon on panels deployed for 1216 days are broad, suggesting intermittent or continuous recruitment in many of the vent-associated species rather than a single episodic recruitment event. Folliculinid and foraminiferan protozoans were the most abundant eucaryotic organisms colonizing long-term deployments at Clam Acres. On the Galapagos spreading center, level of recruitment differed among the vent sites, with Rose Garden > Garden of Eden ? Mussel Bed. Recruitment of vent-associated species was greater on panels placed within vent communities compared to panels placed adjacent to these communities. This observation is consistent with the maintenance of vent communities in discrete regions of hydrothermal flux.

Van Dover, Cindy Lee; Berg, Carl J.; Turner, Ruth D.

1988-10-01

148

Biological Communities at the Florida Escarpment Resemble Hydrothermal Vent Taxa  

Microsoft Academic Search

Dense biological communities of large epifaunal taxa similar to those found along ridge crest vents at the East Pacific Rise were discovered in the abyssal Gulf of Mexico. These assemblages occur on a passive continental margin at the base of the Florida Escarpment, the interface between the relatively impermeable hemipelagic clays of the distal Mississippi Fan and the jointed Cretaceous

C. K. Paull; B. Hecker; R. Commeau; R. P. Freeman-Lynde; C. Neumann; W. P. Corso; S. Golubic; J. E. Hook; E. Sikes; J. Curray

1984-01-01

149

Distribution, Abundance, and Diversity Patterns of the Thermoacidophilic "Deep-Sea Hydrothermal Vent Euryarchaeota 2"  

PubMed Central

Cultivation-independent studies have shown that taxa belonging to the “deep-sea hydrothermal vent euryarchaeota 2” (DHVE2) lineage are widespread at deep-sea hydrothermal vents. While this lineage appears to be a common and important member of the microbial community at vent environments, relatively little is known about their overall distribution and phylogenetic diversity. In this study, we examined the distribution, relative abundance, co-occurrence patterns, and phylogenetic diversity of cultivable thermoacidophilic DHVE2 in deposits from globally distributed vent fields. Results of quantitative polymerase chain reaction assays with primers specific for the DHVE2 and Archaea demonstrate the ubiquity of the DHVE2 at deep-sea vents and suggest that they are significant members of the archaeal communities of established vent deposit communities. Local similarity analysis of pyrosequencing data revealed that the distribution of the DHVE2 was positively correlated with 10 other Euryarchaeota phylotypes and negatively correlated with mostly Crenarchaeota phylotypes. Targeted cultivation efforts resulted in the isolation of 12 axenic strains from six different vent fields, expanding the cultivable diversity of this lineage to vents along the East Pacific Rise and Mid-Atlantic Ridge. Eleven of these isolates shared greater than 97% 16S rRNA gene sequence similarity with one another and the only described isolate of the DHVE2, Aciduliprofundum boonei T469T. Sequencing and phylogenetic analysis of five protein-coding loci, atpA, EF-2, radA, rpoB, and secY, revealed clustering of isolates according to geographic region of isolation. Overall, this study increases our understanding of the distribution, abundance, and phylogenetic diversity of the DHVE2.

Flores, Gilberto E.; Wagner, Isaac D.; Liu, Yitai; Reysenbach, Anna-Louise

2011-01-01

150

Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing ?-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always < 5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to ~150 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that ?-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated that up to ~10 Tg N yr-1 could globally be removed in the subsurface biosphere of hydrothermal vents systems, thus, representing a small fraction of the total marine N loss (~275 to > 400 Tg N yr-1).

Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

2012-11-01

151

Geochemical controls on hydrothermal fluids from the Kairei and Edmond Vent Fields, 23°-25°S, Central Indian Ridge  

NASA Astrophysics Data System (ADS)

Prior to 2000, no mid-ocean ridge hydrothermal systems were identified and sampled in the Indian Ocean. The Kairei field, Central Indian Ridge, was discovered and sampled in 2000 (Gamo et al., 2001; Hashimoto et al., 2001). This paper reports the chemical composition of hydrothermal fluids collected in 2001 from both the Kairei and newly discovered Edmond hydrothermal systems. Data are used to infer subsurface processes and conditions at the two sites, as well as to place them within the global context of known hydrothermal sites on the mid-ocean ridge system. While both sites are located on the intermediate spreading Central Indian Ridge, their hydrologic systems have affinities with those observed on slow spreading ridges. Although the compositions of fluids from the four individual vents sampled at Edmond and the three individual vents sampled at Kairei vary respectively, our interpretation is that a single source fluid at each site is subsequently modified by processes including phase separation, subsurface mixing with seawater, and deposition and/or remobilization of metal-sulfide deposits to generate the observed range of compositions. Both fields are located ?6 km from the neovolcanic zone, on steps on the east wall of the axial valley, with the Edmond field ˜160 km north of Kairei and almost 1000 m deeper (3300 versus 2450 m). The Edmond fluids are extremely hot, with maximum measured temperatures of 382°C compared to 365°C for Kairei. All of the fluids sampled have chlorinities greater than local ambient seawater due to phase separation of seawater at supercritical conditions. Visual observations suggest both sites have been active for a substantial period of time, again similar to observations of slow spreading ridges. Our chemical data suggest that the substrate underlying Kairei is highly altered, while that at Edmond is not. Significant albitization appears to be occurring below the Edmond field, but not at Kairei. The Edmond fluids are by far the hottest brines yet observed venting from a mid-ocean ridge hydrothermal site, resulting in unusually high concentrations of several transition metals.

Gallant, R. M.; von Damm, K. L.

2006-06-01

152

Repetitive Surface-Mounted Multibeam Water Column Imaging of Hydrothermal Vent Plumes over NW Rota 1  

NASA Astrophysics Data System (ADS)

The active hydrothermal plume emanating from the NW Rota 1 seamount was imaged in August 2009 using simultaneously operating 0.5°x1.0° EM710 (70-80 kHz) and 1.0°x1.0° EM122 (11-13 kHz) multibeams. The vent site (Brimstone Pit) lies close to the summit at a depth of 550m. The plume was imaged using east-west passes every 20 minutes for a total period of 9.5 hours. Throughout that period the plume was continuously visible and notably altered in dimension, alignment and scattering strength. The highest scattering strengths and greatest plume widths (50+m) were observed within the lowest 200m above the vent. At 150-200m above the vent the character of the plume changed and split into two narrower (becoming <10m wide) plumes that were strongly sinuous with perturbations of more than 100m horizontally over a height of 100m. Occasionally one of the plumes could be traced to within 75m of the sea surface. The visibility of the upper fainter sections of the plume was notably improved after the deep scattering layer descended at dawn. Over the 9.5 hour period the tilt of the lower plume varied from nearly vertical to inclinations of more than 45°, with azimuths ranging from NW to SW, suggesting a tidal modulation of the over-summit regional currents. The upper plume often exhibited reversed tilt or differing azimuths, suggesting shear within the water column. For about 1 hour, the intensity and width of the lower 200m of the plume notably increased. At the same time a series of distinct high-intensity targets appeared in the lower plume spaced ~ 30m apart vertically. The layered character of the regional deep scattering layer on the upstream and downstream side of the summit was imaged simultaneously for evidence of eddy development in the lee of the seamount. No major turbulence was noted, but for a 1.5 hour period a notable decrease in scattering intensity of one layer at about 500m was seen immediately downstream of the vent. Both multibeams utilize multiple transmit sectors with offset frequencies to maximize stability of seafloor coverage. This complicates the water column imaging, as the scattering strength of both the plume and the deep scattering layer appears strongly frequency-dependent. The along track resolution of the system was limited by two-way travel time. At these depths the EM710 required long chirped pulses precluding dual swath capability, and therefore only achieved 12m along track spacing. The EM122 was using dual swath mode which improved the along track density. Due to sidelobe tracking limitations, only targets within a hemisphere of less than the minimum slant range to the seabed can be unambiguously detected. Surface-mounted water column imaging is still relatively new and appears to be able to fill a scale gap in hydrothermal venting studies between the shorter range ROV-based acoustic imaging used elsewhere (Rona et al. MGR, 2002) and regional “tow-yo” surveys (Walker et al. JGR, 2008) used to date on NW Rota 1. By using sequential imaging over time periods of 10’s of minutes, some aspects of the nature and scale of entrainment within the active plume may be inferred.

Hughes Clarke, J. E.; Martinolich, R.; Broadus, M.

2009-12-01

153

Thermococcus chitonophagus sp. nov., a novel, chitin-degrading, hyperthermophilic archaeum from a deep-sea hydrothermal vent environment  

Microsoft Academic Search

From a hydrothermal vent site off the Mexican west coast (20°50?N, 109°06?W) at a depth of 2,600 m, a novel, hyperthermophilic,\\u000a anaerobic archaeum was isolated. Cells were round to slightly irregular cocci, 1.2–2.5 ?m in diameter and were motile by means\\u000a of a tuft of flagella. The new isolate grew between 60 and 93°C (optimum: 85°C), from pH 3.5 to

Robert Huber; Josef Stöhr; Sabine Hohenhaus; Reinhard Rachel; Siegfried Burggraf; Holger W. Jannasch; Karl O. Stetter

1995-01-01

154

Magnetic and Electron Microscopic Investigation on Rock Samples from the PACMANUS Hydrothermal Vent Field in Papua New Guinea  

NASA Astrophysics Data System (ADS)

The PACMANUS hydrothermal vent field in the Eastern Manus back-arc basin, Papua New Guinea, is considered as a modern-day analog of massive volcanogenic sulfide deposits within felsic volcanic sequence. This active vent field was drilling in November-December 2003 by Ocean Drilling Program Leg 193. The recovery was generally low with less than 15% due to fragility of rocks. Paleomagnetic measurements and scanning electron microscope observations were performed on samples from three major sites (Sites 1188, 1189 and 1191). Site 1188, a low-temperature diffused venting region, was drilled to 370 mbsf. Site 1189, a black smoker region, was drilled to a depth of 200 mbsf using RCB. The recovered rock samples have inclination close to the present-day Earth field (-7° ), but those near the seafloor have much steeper inclination of up to -25° . The upper 35 m of the sites consists of fresh to moderately altered dacite-rhyodacite, which exhibits moderately high natural remanent magnetization (< 6 A/m). The region below this extrusive layer largely comprises of pervasively altered rocks with little evidence of sulfide deposit and as a whole exhibits a low magnetization intensity. However, two intervals with extremely high remanent magnetization were discovered below the upper extrusive layer at Site 1188 (135-211 mbsf and 280-370 mbsf) and one interval at Site 1189 (137-190 mbsf). In particular, the samples between 135-211-mbsf interval at Site 1188 have extremely high remanence with intensities ranging up to 300-500 A/m. Although pockets of magnetite are not uncommon in the ancient hydrothermal ore bodies, they have seldom been documented in modern-day system, and little is known about the physical and chemical condition that allows the magnetite to form in hydrothermal vent systems. Two possibilities of magnetite formation are explored: one that these magnetites precipitated from magnetite-rich fluid as it cooled from above the Curie temperature (TRM) and the other that magnetization was acquired by the growth of magnetite grains below the Curie temperature (CRM).

Lee, S.; Doh, S.; Kim, Y.

2004-12-01

155

Selective predation by the zoarcid fish Thermarces cerberus at hydrothermal vents  

NASA Astrophysics Data System (ADS)

This study investigates predation by the vent zoarcid fish Thermarces cerberus through gastrointestinal analyses of 27 specimens collected with the submersible ALVIN at vents at 9°50'N on the East Pacific Rise. T. cerberus fed most frequently on gastropod mollusks (mainly Lepetodrilus elevatus) and amphipod crustaceans (mainly Ventiella sulfuris). Species found occasionally in high abundance included the swarming amphipod Halice hesmonectes and the snail Cyathermia naticoides. Other items also found in gastrointestinal tracts, but in very low numbers, included polychaete worms, crustaceans and unidentified tissue clumps. The comparison between the size distribution of L. elevatus limpets ingested by T. cerberus and those found attached to vestimentiferan tubes suggest that the fish may selectively prey on large limpets. If the selective removal of large Lepetodrilus spp. limpets by T. cerberus does occur, then it would have potential community-level consequences at hydrothermal vents, since these mobile gastropods appear to inhibit the settlement of sessile vent species, including tube-building worms. Our results suggest possible direct and indirect effects of T. cerberus on benthic community structure at hydrothermal vents on the East Pacific Rise.

Sancho, G.; Fisher, C. R.; Mills, S.; Micheli, F.; Johnson, G. A.; Lenihan, H. S.; Peterson, C. H.; Mullineaux, L. S.

2005-05-01

156

Detection of Putatively Thermophilic Anaerobic Methanotrophs in Diffuse Hydrothermal Vent Fluids  

PubMed Central

The anaerobic oxidation of methane (AOM) is carried out by a globally distributed group of uncultivated Euryarchaeota, the anaerobic methanotrophic arachaea (ANME). In this work, we used G+C analysis of 16S rRNA genes to identify a putatively thermophilic ANME group and applied newly designed primers to study its distribution in low-temperature diffuse vent fluids from deep-sea hydrothermal vents. We found that the G+C content of the 16S rRNA genes (PGC) is significantly higher in the ANME-1GBa group than in other ANME groups. Based on the positive correlation between the PGC and optimal growth temperatures (Topt) of archaea, we hypothesize that the ANME-1GBa group is adapted to thrive at high temperatures. We designed specific 16S rRNA gene-targeted primers for the ANME-1 cluster to detect all phylogenetic groups within this cluster, including the deeply branching ANME-1GBa group. The primers were successfully tested both in silico and in experiments with sediment samples where ANME-1 phylotypes had previously been detected. The primers were further used to screen for the ANME-1 microorganisms in diffuse vent fluid samples from deep-sea hydrothermal vents in the Pacific Ocean, and sequences belonging to the ANME-1 cluster were detected in four individual vents. Phylotypes belonging to the ANME-1GBa group dominated in clone libraries from three of these vents. Our findings provide evidence of existence of a putatively extremely thermophilic group of methanotrophic archaea that occur in geographically and geologically distinct marine hydrothermal habitats.

Huber, Julie A.; Chernyh, Nikolay A.; Bonch-Osmolovskaya, Elizaveta A.; Lebedinsky, Alexander V.

2013-01-01

157

Rare earth elements in seawater near hydrothermal vents  

Microsoft Academic Search

Rare earth element (REE) patterns in the deep Pacific are strongly depleted in the lighter elements and have a large negative cerium anomaly. These REE patterns and associated concentration-depth profiles are maintained by regeneration in deep waters modified by preferential scavenging of the lighter elements. Scavenging by iron- and manganese-rich hydrothermal plumes might explain why vast areas of sediments far

G. Klinkhammer; H. Elderfield; A. Hudson

1983-01-01

158

Widespread Occurrence of Two Carbon Fixation Pathways in Tubeworm Endosymbionts: Lessons from Hydrothermal Vent Associated Tubeworms from the Mediterranean Sea  

PubMed Central

Vestimentiferan tubeworms (siboglinid polychetes) of the genus Lamellibrachia are common members of cold seep faunal communities and have also been found at sedimented hydrothermal vent sites in the Pacific. As they lack a digestive system, they are nourished by chemoautotrophic bacterial endosymbionts growing in a specialized tissue called the trophosome. Here we present the results of investigations of tubeworms and endosymbionts from a shallow hydrothermal vent field in the Western Mediterranean Sea. The tubeworms, which are the first reported vent-associated tubeworms outside the Pacific, are identified as Lamellibrachia anaximandri using mitochondrial ribosomal and cytochrome oxidase I (COI) gene sequences. They harbor a single gammaproteobacterial endosymbiont. Carbon isotopic data, as well as the analysis of genes involved in carbon and sulfur metabolism indicate a sulfide-oxidizing chemoautotrophic endosymbiont. The detection of a hydrogenase gene fragment suggests the potential for hydrogen oxidation as alternative energy source. Surprisingly, the endosymbiont harbors genes for two different carbon fixation pathways, the Calvin-Benson-Bassham (CBB) cycle as well as the reductive tricarboxylic acid (rTCA) cycle, as has been reported for the endosymbiont of the vent tubeworm Riftia pachyptila. In addition to RubisCO genes we detected ATP citrate lyase (ACL – the key enzyme of the rTCA cycle) type II gene sequences using newly designed primer sets. Comparative investigations with additional tubeworm species (Lamellibrachia luymesi, Lamellibrachia sp. 1, Lamellibrachia sp. 2, Escarpia laminata, Seepiophila jonesi) from multiple cold seep sites in the Gulf of Mexico revealed the presence of acl genes in these species as well. Thus, our study suggests that the presence of two different carbon fixation pathways, the CBB cycle and the rTCA cycle, is not restricted to the Riftia endosymbiont, but rather might be common in vestimentiferan tubeworm endosymbionts, regardless of the habitat.

Thiel, Vera; Hugler, Michael; Blumel, Martina; Baumann, Heike I.; Gartner, Andrea; Schmaljohann, Rolf; Strauss, Harald; Garbe-Schonberg, Dieter; Petersen, Sven; Cowart, Dominique A.; Fisher, Charles R.; Imhoff, Johannes F.

2012-01-01

159

Phylogenetic characterization of the epibiotic bacteria associated with the hydrothermal vent polychaete Alvinella pompejana.  

PubMed Central

Alvinella pompejana is a polychaetous annelid that inhabits active deep-sea hydrothermal vent sites along the East Pacific Rise, where it colonizes the walls of actively venting high-temperature chimneys. An abundant, morphologically diverse epibiotic microflora is associated with the worm's dorsal integument, with a highly integrated filamentous morphotype clearly dominating the microbial biomass. It has been suggested that this bacterial population participates in either the nutrition of the worm or in detoxification of the worm's immediate environment. The primary goal of this study was to phylogenetically characterize selected epibionts through the analysis of 16S rRNA gene sequences. Nucleic acids were extracted from bacteria collected from the dorsal surface of A. pompejana. 16S rRNA genes were amplified with universal bacterial primers by the PCR. These genes were subsequently cloned, and the resulting clone library was screened by restriction fragment length polymorphism analysis to identify distinct clone types. The restriction fragment length polymorphism analysis identified 32 different clone families in the library. Four of these families were clearly dominant, representing more than 65% of the library. Representatives from the four most abundant clone families were chosen for complete 16S rRNA gene sequencing and phylogenetic analysis. These gene sequences were analyzed by a variety of phylogenetic inference methods and found to be related to the newly established epsilon subdivision of the division Proteobacteria. Secondary structural model comparisons and comparisons of established signature base positions in the 16S rRNA confirmed the placement of the Alvinella clones in the epsilon subdivision of the Proteobacteria.

Haddad, A; Camacho, F; Durand, P; Cary, S C

1995-01-01

160

Study on the high precision acoustic measurement techniques for determining temperature field around seafloor hydrothermal vent  

NASA Astrophysics Data System (ADS)

This paper presents the basis of acoustic method used for temperature field measurement of seafloor hydrothermal vent and two techniques of the parabolic interpolation and the bending compensation of propagation paths of acoustic signal are introduced. Experimental research is performed to exactly rebuild the temperature field around hot springs on the floor of Qiezishan Lake, Yunnan, China. The accuracy of the travel time estimation has been improved based on the aforementioned technique and method. At the same time, by comparison of the results of temperature field with different means, the max absolute error, the maximum relative error and the root mean square error are given. It shows that the technique and the method presented in the paper can be applied to the temperature field measurement detector around the seafloor hydrothermal vent. It also has a good accuracy.

Cai, Yong; Fan, Wei; Zhou, Yan; Fu, Xian-qiao; Fang, Hui; Jin, Tao

2012-12-01

161

[Comment on “Submarine hot springs: Origin of life?”] Hydrothermal vents revisited  

NASA Astrophysics Data System (ADS)

It was gratifying to read Peter Bell's synopsis of our paper [Corliss et al., 1981] in the March 23 issue of Eos (Submarine hot springs: Origin of life?) however, in the last sentence, he wrote, ‘They note that microorganisms found in recent expeditions to the submarine hot springs of the East Pacific Rise would be evidence that the processes are still occurring.’In our final paragraph we actually said that while “events leading to the formation of complex organic compounds and “protocell” structures may still be occurring in present-day oceanic hydrothermal systems … the complex communities of bacteria in modern oceanic environments would outcompete and consume abiotically synthesized protocells…” Modern-day vent microbiota will probably mask or destroy any evidence for abiotic synthesis in the hydrothermal vents.

Hoffman, Sarah

162

Thermal adaptations in deep-sea hydrothermal vent and shallow-water shrimp  

NASA Astrophysics Data System (ADS)

The hydrothermal vent shrimp Mirocaris fortunata is commonly exposed to acute thermal gradients and rapid fluctuations in water temperature. The shallow-water shrimp Palaemonetes varians experiences less acute but similar magnitude fluctuations in its thermal regime. Acute respiratory response to temperature shock, and temperature preference was assessed for both species. Oxygen consumption rates were assessed across the natural temperature range reported for M. fortunata. Rates increased with temperature for both species. P. varians had a significantly higher rate of oxygen consumption than M. fortunata at all temperatures except 4 °C. The rate of increase in oxygen consumption with increasing temperature was also significantly greater for P. varians. M. fortunata selected a significantly higher temperature than P. varians. Mirocaris fortunata maintains its metabolism at a more stable rate, which is likely an adaptation to acute changes in temperatures occurring at hydrothermal vents.

Smith, Felix; Brown, Alastair; Mestre, Nélia C.; Reed, Adam J.; Thatje, Sven

2013-08-01

163

Lithium isotopic systematics of hydrothermal vent fluids at the Main Endeavour Field, Northern Juan de Fuca Ridge  

Microsoft Academic Search

Vent fluids issuing from the Main Endeavour Field (MEF), Juan de Fuca Ridge, were analyzed for ?7Li to help constrain subseafloor hydrothermal alteration and phase separation processes. Magmatic activity prior to sampling of the fluids in 1999 enhanced heat and mass transfer, as indicated by the large scale, but temporary, changes in vent fluid chemistry. In particular, dissolved chloride concentrations

D. I. Foustoukos; R. H. James; M. E. Berndt; W SEYFRIEDJR

2004-01-01

164

Metaproteomic Analysis of a Chemosynthetic Hydrothermal Vent Community Reveals Insights into Key-Metabolic Processes  

NASA Astrophysics Data System (ADS)

In 2005 researchers at the Centre for Geobiology, University of Bergen, Norway, discovered two active vent fields at the southwestern Mohns Ridge in the Norwegian-Greenland Sea. The fields harbours both low-temperature iron deposits and high-temperature white smoker vents. Distinct microbial mats were abundantly present and located in close vicinity to the hydrothermal vent sites. Characteristics of the mat environment were steep physical and chemical gradients with temperatures ranging from 10°C in the top layer to 90°C at 10 cm bsf and high concentrations of hydrogen sulfide and methane. The work presented here focus on the In situ community activities, and is part of an integrated strategy combining metagenomics, metatranscriptomics and metaproteomics to in-depth characterise these newly discovered hydrothermal vent communities. Extracted proteins were separated via SDS-PAGE. Peptides extracted after In-gel tryptic digest was injected into an Ultimate 3000 nanoLC system connected to a linear quadropole ion trap-orbitrap (LTQ-Orbitrap XL) mass spectrometer equipped with a nanoelectrospray ion source. A custom database of open reading frames (ORFs) from the combined metatranscriptome and metagenome datasets was implemented and searched against using Mascot 2.2; the IRMa tool box [1] was used in peptide validation. Validated ORFs were subjected to a Blastp search against Refseq with an E-value cut-off of 0.001. A total of 1097 proteins with ? 2 peptides were identified of which 921 gave a hit against Refseq, containing 519 unique proteins. Key enzymes of the sulfur oxidation pathway (sox) were found, which were taxonomically affiliated to Epsilonproteobacteria. In addition, this group actively expressed hydrogenases and membrane proteins involved in aerobic and anaerobic respiratory chains. Enzymes of dissimilatory sulfate-reduction (APS-reductase, AprAB and DsrA2) were found with closest hit to members of the Deltaproteobacteria. These findings indicate an internal sulfur cycle within the community. The community contained expressed enzymes of a variety of carbon metabolism pathways. Key enzymes of the reverse TCA cycle for fixation of CO2 and the Wood-Ljungdahl pathway for oxidation of acetyl-CoA and / or the fixation of CO2 were found. Key enzymes of aerobic and anaerobic methane-oxidation pathways were identified as well, namely particulate methane monooxygenase and methyl-Coenzyme M reductase. Various house-keeping gene-products, like cold- and heat shock proteins as well as ribosomal proteins and ATP synthases were identified. This approach has a future potential of broadening our understanding of environmental complexity and regulation in response to geochemical constraints. [1] Dupierris, V., Masselon, C., Court, M., Kieffer-Jaquinod, S., and Bruley, C. (2009) A toolbox for validation of mass spectrometry peptides identification and generation of database: IRMa. Bioinformatics 25, 1980-1981.

Steen, I.; Stokke, R.; Lanzen, A.; Pedersen, R.; Øvreås, L.; Urich, T.

2010-12-01

165

Post-capture investigations of hydrothermal vent macro-invertebrates to study adaptations to extreme environments  

Microsoft Academic Search

Typical survival strategies, developed by macro-invertebrates at a variety of reducing marine habitats including deep-sea\\u000a hydrothermal vents, have been the subject of the laboratory experimentation over the past three decades. This review provides\\u000a an insight into the international efforts that have converged on the area of laboratory maintenance of such species whose\\u000a nutritional requirements are outside the usual scope of

Eniko Kadar; Jonathan J. Powell

166

Episodic venting of hydrothermal fluids from the Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

Evidence of large-scale episodic venting of hydrothermal fluids was initially discovered in August 1986 in the form of a 130-km3 radially symmetric "megaplume" over the southern Juan de Fuca Ridge. We report here on the discovery in September 1987 of a second, smaller megaplume about 45 km north of the location of the first megaplume. The 3He/heat, 3He/dissolved Mn, and 3He/dissolved silica ratios in both megaplumes were typical of high-temperature vent fluids. Evidence from long-term records of current flow over the southern Juan de Fuca Ridge, and from the mineralogy and Mn chemistry of megaplume particles, makes it unlikely that the second megaplume was a reencounter of the first. A plume model that relates the heat flux to the observed plume rise height of ˜1000 m finds that the total heat content of the fluids that formed the megaplumes was 1016-1017 J, or equivalently a fluid volume of 3-8 × 107 m3 at 350°C. The geometry and suspended particle population of the first megaplume imply that such features are formed within a few days time. The extraordinary heat and volume fluxes associated with megaplumes (102-103 greater than ordinary vent fields), as well as their typical hydrothermal chemistry, suggest that they resulted from tectonic or hydraulic fracturing that suddenly increased the permeability of the hydrothermal fluid reservoir in the axial crust. The flux of hydrothermal heat from continuous venting and episodic megaplumes on the southern Juan de Fuca Ridge is presently 4 - 10 × 109 W, a factor of 5-10 greater than various geophysical model calculations for this ridge segment. This imbalance may be symptomatic of a recent surge in the local cycle of magmatic activity.

Baker, E. T.; Lavelle, J. W.; Feely, R. A.; Massoth, G. J.; Walker, S. L.; Lupton, J. E.

1989-07-01

167

Borders of life: lessons from Microbiology of deep-sea hydrothermal vents  

Microsoft Academic Search

Thirty years ago, the deep-sea was known as a low density biotope due to coldness, darkness and famine-like conditions. The discovery of deep-sea hydrothermal vents in the Eastern Pacific in 1977 and the associated black smokers in 1979 considerably changed our views about life on Earth. For the first time, an ecosystem almost independent (at least for tens of years)

D. Prieur

2004-01-01

168

Does sulphide detoxication occur in the gills of the hydrothermal vent shrimp, Rimicaris exoculata ?  

Microsoft Academic Search

Ultrastructural observations of the gills of the hydrothermal vent shrimp Rimicaris exoculata reveal that the epithelial cells contain numerous mitochondria clustered around unusual organelles (diameter of 0.7 to 2.5 ?m) containing membrane stacks. These organelles were termed sulphide-oxidising bodies (SOBs) by structural analogy with organelles observed in the tissues of species adapted to sulphide-rich environments. Moreover, in the gills of R. exoculata,

Philippe Compère; Anne-Sophie Martinez; Mireille Charmantier-Daures; Jean-Yves Toullec; Gerhard Goffinet; Françoise Gaill

2002-01-01

169

Adaptations to hypoxia in hydrothermal-vent and cold-seep invertebrates  

Microsoft Academic Search

The deep sea harbors very unusual environments, such as hydrothermal vents and cold seeps, that illustrate an apparent paradox:\\u000a the environmental conditions are very challenging and yet they display a high biomass when compared to the surrounding environment\\u000a at similar depth. Hypoxia is one of the challenges that these species face to live there. Here, we review specific adaptations\\u000a of

Stéphane Hourdez; François H. Lallier

170

Adaptations to hypoxia in hydrothermal-vent and cold-seep invertebrates  

Microsoft Academic Search

The deep sea harbors very unusual environments, such as hydrothermal vents and cold seeps, that illustrate an apparent paradox:\\u000a the environmental conditions are very challenging and yet they display a high biomass when compared to the surrounding environment\\u000a at similar depth. Hypoxia is one of the challenges that these species face to live there. Here, we review specific adaptations\\u000a of

Stéphane Hourdez; François H. Lallier

2007-01-01

171

Biogeography of Persephonella in deep-sea hydrothermal vents of the Western Pacific.  

PubMed

Deep-sea hydrothermal vent fields are areas on the seafloor with high biological productivity fueled by microbial chemosynthesis. Members of the Aquificales genus Persephonella are obligately chemosynthetic bacteria, and appear to be key players in carbon, sulfur, and nitrogen cycles in high temperature habitats at deep-sea vents. Although this group of bacteria has cosmopolitan distribution in deep-sea hydrothermal ecosystem around the world, little is known about their population structure such as intraspecific genomic diversity, distribution pattern, and phenotypic diversity. We developed the multi-locus sequence analysis (MLSA) scheme for their genomic characterization. Sequence variation was determined in five housekeeping genes and one functional gene of 36 Persephonella hydrogeniphila strains originated from the Okinawa Trough and the South Mariana Trough (SNT). Although the strains share >98.7% similarities in 16S rRNA gene sequences, MLSA revealed 35 different sequence types (ST), indicating their extensive genomic diversity. A phylogenetic tree inferred from all concatenated gene sequences revealed the clustering of isolates according to the geographic origin. In addition, the phenotypic clustering pattern inferred from whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis can be correlated to their MLSA clustering pattern. This study represents the first MLSA combined with phenotypic analysis indicative of allopatric speciation of deep-sea hydrothermal vent bacteria. PMID:23630523

Mino, Sayaka; Makita, Hiroko; Toki, Tomohiro; Miyazaki, Junichi; Kato, Shingo; Watanabe, Hiromi; Imachi, Hiroyuki; Watsuji, Tomo-O; Nunoura, Takuro; Kojima, Shigeaki; Sawabe, Tomoo; Takai, Ken; Nakagawa, Satoshi

2013-04-25

172

The sound field near hydrothermal vents on Axial Seamount, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

High-quality acoustic noise measurements were obtained by two hydrophones located 3 m and 40 m from an active hydrothermal vent on Axial Seamount, Juan de Fuca Ridge, in an effort to determine the feasibility of monitoring hydrothermal vent activity through flow noise generation. Most of the measured noise field could be attributed to ambient ocean noise sources of microseisms, distant shipping, and weather, punctuated by local ships and biological sources. Long-period, low-velocity, water/rock interface waves were detected with high amplitudes which rapidly decayed with distance from the seafloor. Detection of vent signals was hampered by unexpected spatial nonstationarity due to the shadowing effects of the caldera wall. No continuous vent signals were deemed significant based on a criterion of 90% probability of detection and 5% probability of false alarm. However, a small signal near 40 Hz, with a power level of 10-4Pa2/Hz was noticed on two records taken within 3 m of the Inferno black smoker. Hie frequency of this signal is consistent with predictions, and the power level suggests the occurrence of jet noise amplification due to convected density inhomogeneities.

Little, Sarah A.; Stolzenbach, Keith D.; Purdy, G. Michael

1990-08-01

173

Sound field near hydrothermal vents on Axial Seamount, Juan de Fuca Ridge. Technical report  

SciTech Connect

High-quality acoustic noise measurements were obtained by two hydrophones located 3 m and 40 m from an active hydrothermal vent on Axial Seamount, Juan de Fuca Ridge, in an effort to determine the feasibility of monitoring hydrothermal vent activity through flow noise generation. Most of the measured noise field could be attributed to ambient ocean noise sources of microseisms, distant shipping, and weather, punctuated by local ships and biological sources. Long-period, low-velocity, water/rock interface waves were detected with high amplitudes which rapidly decayed with distance from the seafloor. Detection of vent signals was hampered by unexpected spatial nonstationarity due to the shadowing effects of the calders wall. No continuous vent signals were deemed significant based on a criterion of 90% probability of detection and 5% probability of false alarm. However, a small signal near 40 Hz, with a power level of 0.0001 Pa sq/Hz was noticed on two records taken within 3 m of the Inferno black smoker. The frequency of this signal is consistent with predictions, and the power level suggests the occurrence of jet noise amplification due to convected density inhomogeneities. Keywords: Seamounts; Flow noise; Underwater acoustics; Acoustic measurement; Geothermy/noise; Ocean ridges; Underwater sound signals; Reprints; North Pacific Ocean. (EDC).

Little, S.A.; Stolzenbach, K.D.; Purdy, G.M.

1990-08-10

174

Variable morphologic expression of volcanic, tectonic, and hydrothermal processes at six hydrothermal vent fields in the Lau back-arc basin  

Microsoft Academic Search

Ultrahigh-resolution bathymetric maps (25 cm grid) are used to quantify the physical dimensions of and spatial relationships between tectonic, volcanic, and hydrothermal features at six hydrothermal vent fields in the Lau back-arc basin. Supplemented with near-bottom photos, and nested within regional DSL-120A side-scan sonar data, these maps provide insight into the nature of hydrothermal systems along the Eastern Lau Spreading

Vicki Lynn Ferrini; Margaret K. Tivey; Suzanne M. Carbotte; Fernando Martinez; Chris Roman

2008-01-01

175

Conjugating effects of symbionts and environmental factors on gene expression in deep-sea hydrothermal vent mussels  

PubMed Central

Background The deep-sea hydrothermal vent mussel Bathymodiolus azoricus harbors thiotrophic and methanotrophic symbiotic bacteria in its gills. While the symbiotic relationship between this hydrothermal mussel and these chemoautotrophic bacteria has been described, the molecular processes involved in the cross-talking between symbionts and host, in the maintenance of the symbiois, in the influence of environmental parameters on gene expression, and in transcriptome variation across individuals remain poorly understood. In an attempt to understand how, and to what extent, this double symbiosis affects host gene expression, we used a transcriptomic approach to identify genes potentially regulated by symbiont characteristics, environmental conditions or both. This study was done on mussels from two contrasting populations. Results Subtractive libraries allowed the identification of about 1000 genes putatively regulated by symbiosis and/or environmental factors. Microarray analysis showed that 120 genes (3.5% of all genes) were differentially expressed between the Menez Gwen (MG) and Rainbow (Rb) vent fields. The total number of regulated genes in mussels harboring a high versus a low symbiont content did not differ significantly. With regard to the impact of symbiont content, only 1% of all genes were regulated by thiotrophic (SOX) and methanotrophic (MOX) bacteria content in MG mussels whereas 5.6% were regulated in mussels collected at Rb. MOX symbionts also impacted a higher proportion of genes than SOX in both vent fields. When host transcriptome expression was analyzed with respect to symbiont gene expression, it was related to symbiont quantity in each field. Conclusions Our study has produced a preliminary description of a transcriptomic response in a hydrothermal vent mussel host of both thiotrophic and methanotrophic symbiotic bacteria. This model can help to identify genes involved in the maintenance of symbiosis or regulated by environmental parameters. Our results provide evidence of symbiont effect on transcriptome regulation, with differences related to type of symbiont, even though the relative percentage of genes involved remains limited. Differences observed between the vent site indicate that environment strongly influences transcriptome regulation and impacts both activity and relative abundance of each symbiont. Among all these genes, those participating in recognition, the immune system, oxidative stress, and energy metabolism constitute new promising targets for extended studies on symbiosis and the effect of environmental parameters on the symbiotic relationships in B. azoricus.

2011-01-01

176

Extremely Thermophilic Fermentative Archaebacteria of the Genus Desulfurococcus from Deep-Sea Hydrothermal Vents  

PubMed Central

Two strains of extremely thermophilic, anaerobic bacteria are described that are representative of isolates obtained from a variety of oceanic hydrothermal vent sites at depths from 2,000 to 3,700 m. The isolates were similar in their requirements for complex organic media, elemental sulfur, and seawater-range salinities (optimum, 2.1 to 2.4%); their high tolerance for sulfide (100 mM) and oxic conditions below growth-range temperatures (50 to 95°C); and their archaebacterial characteristics: absence of murein, presence of certain diand tetraethers, and response to specific antibiotics. The two strains (S and SY, respectively) differed slightly in their optimum growth temperatures (85 and 90°C, optimum pHs for growth (7.5 and 7.0), and DNA base compositions (52.01 and 52.42 G+C mol%). At their in situ pressure of about 250 atm (25,313 kPa), growth rates at 80 and 90°C were about 40% lower than those at 1 atm (101.29 kPa), and no growth occurred at 100 and 110°C, respectively, at either pressure. In yeast extract medium, only 2% of the organic carbon was used and appeared to stem largely from the proteinaceous constituents. According to physiological criteria, the isolates belong to the genus Desulfurococcus. Images

Jannasch, Holger W.; Wirsen, Carl O.; Molyneaux, Stephen J.; Langworthy, Thomas A.

1988-01-01

177

Geological and hydrothermal controls on the distribution of megafauna in Ashes Vent Field, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

A computerized data base was constructed to aid in the interpretation of biological and geological observations recorded from 7662 photographs taken of Ashes vent field (located along the SW wall of the summit caldera of Axial Volcano, Juan de Fuca Ridge) during 1985-1986 using the Pisces IV submersible and a towed camera system. The transition region between the locus of high-temperature vents in Ashes vent field (i.e., Inferno, 326°C; Hell, 301°C; and Virgin Mound, 298°C) and more typical environmental conditions for the summit caldera of Axial Volcano as a whole is zoned spatially with respect to sediment type and organism assemblage. Three general ecological zones are identified within the vent field: (1) the central vent zone (within 100 m of a high-temperature vent), dominated by vent-associated organisms (vestimentiferan tube worms, clams, bacterial mats) and sedimentation (high-temperature, plume-derived and low-temperature, in situ deposits); (2) the distal vent zone (100-725 m from any high-temperature vent), characterized by extensive fields of iron oxide, iron silicate and silica chimneys and sediment (nontronite assemblage material), as well as maximum densities of most nonvent fauna; and (3) the nonvent impact zone (725-1300 m), indicated by elevated densities of nonvent organisms relative to regional (i.e., caldera-wide) values and maximum Bathydorus sp. sponge densities. The distribution of vestimentiferan tube worms is limited to within 90 m of known high-temperature venting (central vent zone); and anemones were observed only between 30 and 40 m from hot vents. Clams and microbial mats are concentrated in the central vent zone, as well, but occur sporadically up to 1250 m from the hot vents in association with hydrothermal nontronite that is probably precipitating in situ from <60°C vent fluid; thus megafaunal distributions are a useful indicator of poorly defined, often diffuse low-temperature hydrothermal activity on the seafloor. Maximum densities of nonvent echinoderms (i.e., holothurians, sea stars, urchins) are associated with the distal venting zone. Distributions of megafauna not endemic to the vent environment are sensitive to both local geology (particularly the nature of the substrate) and effects of hydrothermal activity such as enhanced food availability or hydrothermal sedimentation. Although evidence for active venting is not apparent in the nonvent impact zone, photographic data suggest that the type and number of megafauna living in this region are significantly influenced by proximity to low- and high-temperature hydrothermal sources that support enhanced microbial production and produce sediment of hydrothermal origin, which may be advected to the peripheral environment. Statistical interpretation of photographic data suggests an outer limit to the extent of vent influence on benthic megafauna (i.e., Bathydorus sp. sponges) of about 1000-1300 m for the hydrothermal system active at Ashes vent field in 1985-1986. On the scale of a single vent field, hydrothermal activity apparently results in a less patchy distribution of benthic, nonvent organisms within the central and distal vent zones than is common in the nonvent environment.

Arquit, Anne M.

1990-08-01

178

Formation of Zn- and Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: implications for sulfide bioavailability to chemoautotrophs  

PubMed Central

Background The speciation of dissolved sulfide in the water immediately surrounding deep-ocean hydrothermal vents is critical to chemoautotrophic organisms that are the primary producers of these ecosystems. The objective of this research was to identify the role of Zn and Fe for controlling the speciation of sulfide in the hydrothermal vent fields at the Eastern Lau Spreading Center (ELSC) in the southern Pacific Ocean. Compared to other well-studied hydrothermal systems in the Pacific, the ELSC is notable for unique ridge characteristics and gradients over short distances along the north-south ridge axis. Results In June 2005, diffuse-flow (< 50°C) and high-temperature (> 250°C) vent fluids were collected from four field sites along the ELSC ridge axis. Total and filtered Zn and Fe concentrations were quantified in the vent fluid samples using voltammetric and spectrometric analyses. The results indicated north-to-south variability in vent fluid composition. In the high temperature vent fluids, the ratio of total Fe to total Zn varied from 39 at Kilo Moana, the most northern site, to less than 7 at the other three sites. The concentrations of total Zn, Fe, and acid-volatile sulfide indicated that oversaturation and precipitation of sphalerite (ZnS(s)) and pyrite (FeS2(s)) were possible during cooling of the vent fluids as they mixed with the surrounding seawater. In contrast, most samples were undersaturated with respect to mackinawite (FeS(s)). The reactivity of Zn(II) in the filtered samples was tested by adding Cu(II) to the samples to induce metal-exchange reactions. In a portion of the samples, the concentration of labile Zn2+ increased after the addition of Cu(II), indicating the presence of strongly-bound Zn(II) species such as ZnS clusters and nanoparticles. Conclusion Results of this study suggest that Zn is important to sulfide speciation at ELSC vent habitats, particularly at the southern sites where Zn concentrations increase relative to Fe. As the hydrothermal fluids mix with the ambient seawater, Zn-sulfide clusters and nanoparticles are likely preventing sulfide oxidation by O2 and reducing bioavailability of S(-II) to organisms.

Hsu-Kim, Heileen; Mullaugh, Katherine M; Tsang, Jeffrey J; Yucel, Mustafa; Luther, George W

2008-01-01

179

Hydrocarbons in hydrothermal vent fluids: the role of chromium-bearing catalysts.  

PubMed

Fischer-Tropsch type (FTT) synthesis has long been proposed to account for the existence of hydrocarbons in hydrothermal fluids. We show that iron- and chromium-bearing minerals catalyze the abiotic formation of hydrocarbons. In addition to production of methane (CH4aq), we report abiotic generation of ethane (C2H6aq) and propane (C3H8aq) by mineral-catalyzed hydrothermal reactions at 390 degrees C and 400 bars. Results suggest that the chromium component in ultramafic rocks could be an important factor for FTT synthesis during water-rock interaction in mid-ocean ridge hydrothermal systems. This in turn could help to support microbial communities now recognized in the subsurface at deep-sea vents. PMID:15060286

Foustoukos, Dionysis I; Seyfried, William E

2004-04-01

180

Evidence for hydrothermal venting in Fe isotope compositions of the deep Pacific Ocean through time  

NASA Astrophysics Data System (ADS)

Temporal variations in Fe isotope compositions at three locations in the Pacific Ocean over the last 10 Ma are inferred from high-resolution analyses of three hydrogenetic ferromanganese crusts. Iron pathways to the central deep Pacific Ocean appear to have remained constant over the past 10 Ma, reflected by a remarkably constant Fe isotope composition, despite large changes in the Fe delivery rates to the surface ocean via dust. These results suggest that the Fe cycle in the deep ocean is decoupled from that in surface waters. By contrast, one ferromanganese crust from the Izu-Bonin (IB) back-arc/marginal basin of the W. Pacific exhibits large ? 56Fe variations. In that crust, decreases in ? 56Fe values correlate with increases in Mn, Mg, Ni, Cu, Zn, Mo, and V contents, and consistent with periods of intense hydrothermal input and increased growth rates. A second crust located within 100 km of the first IB sample does not record any of these periods of enhanced hydrothermal input. This probably reflects the isolated pathways by which hydrothermally sourced Fe may have migrated in the back arc, highlighting the high degree of provinciality that Fe isotopes may have in the modern (oxic) oceans. Our results demonstrate that despite efficient removal at the source, hydrothermal Fe injected into the deep ocean could account for a significant fraction of the dissolved Fe pool in the deep ocean, and that hydrothermally sourced Fe fluxes to the open ocean may have lower ? 56Fe values than those measured so far in situ at hydrothermal vents. Correlation between ? 56Fe values and elements enriched in hydrothermal fluids may provide a means for distinguishing hydrothermal Fe from other low-? 56Fe sources to the oceans such as dissolved riverine Fe or porewaters in continental shelf sediments.

Chu, N.-C.; Johnson, C. M.; Beard, B. L.; German, C. R.; Nesbitt, R. W.; Frank, M.; Bohn, Marcel; Kubik, P. W.; Usui, A.; Graham, I.

2006-05-01

181

Interactions of Deep-Sea Vent Invertebrates with Their Environment: The Case of Rimicaris exoculata  

Microsoft Academic Search

The vent shrimp Rimicaris exoculata thrives around many hydrothermal vent sites along the Mid-Atlantic Ridge (MAR), where it aggregates into dense swarms. In contrast to hydrothermal vent fields at the East Pacific Rise (EPR), where the biomass is dominated by tubeworms, clams, and mussels, this shrimp is one of the major animal species at MAR vents. These animals are found

Caroline Schmidt; Nadine Le Bris; Françoise Gaill

2008-01-01

182

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

183

Ubiquity of Deep-Sea Hydrothermal Vent Archaea in the Global Subsurface Biosphere  

NASA Astrophysics Data System (ADS)

Recent microbiological surveys of terrestrial and oceanic subsurface biosphere have revealed that sizable microbial populations are present in the global subsurface environments. However, little is known about the community structure, the genetic diversity and the distribution pattern of the subsurface bacteria and archaea since these surveys are mainly dependent on microscopic observations and conventional cultivation techniques. Culture-independent, molecular phylogenetic techniques are now applied to explore microbial communities in various subsurface environments such as underground mines, subterrestrial rocks, continental and ocean oil reservoirs, subseafloor pelagic sediments and methane hydrates, and subvent microbial ecosystems. It becomes apparent that unique archaeal components are commonly present in these subsurface microbial habitats whereas archaea are always less abundant than bacteria. Most frequently recovered genetic signatures are of hyperthermophiles Thermococcus and extreme halophiles Haloarcula members. Unexpected ubiquity of them even in non-extreme, subsurface environments may represent the great mass potential of probably dormant extremophilic archaea in the global subsurface biosphere. Archaeal populations in deep-sea hydrothermal vents and the subvent environments might serve as sources of the dormant extremophiles, the silent majority of archaea. It seems likely therefore that the global and local ocean hydrothermal activities persistently have a great impact on the formation of subsurface microbial communities and the distribution of subsurface microorganisms. In the KR01-09 cruise which was named ?geomicrobiological investigation of subseafloor biosphere associated with deep-sea hydrothermal activity in the Okinawa Trough?, active populations of hyperthermophilic archaea Thermococcus were detected from non-hydrothermal subseafloor sediments. Their viability was likely correlated with the distance and the duration from the deep-sea hydrothermal vent activities. It will be discussed how the extremophilic archaea are propagated in the global subsurface biosphere.

Takai, K.; Inagaki, F.; Horikoshi, K.

2001-12-01

184

Bioavailability, Bioaccumulation and Biotransformation of arsenic in coral reef organisms surrounding an arsenic-rich marine shallow-water hydrothermal vent system in the coastal waters of Ambitle Island, Papua New Guinea  

NASA Astrophysics Data System (ADS)

Marine shallow-water hydrothermal systems are often enriched in biologically toxic elements, thus making them ideal natural analogs for coastal anthropogenic pollution. Here, we report our investigation of the bioavailability, bioaccumulation, and biotransformation of hydrothermally-derived arsenic into several coral reef organisms from the arsenic-rich marine shallow-water hydrothermal system of Tutum Bay, Ambitle Island, in northeastern Papua New Guinea. Hydrothermal venting provided bioavailable As by two major pathways throughout Tutum Bay: 1) easily-exchangeable As from hydrothermally influenced sediments to as far away as 200 m from focused venting, and 2) in surface seawaters, which may allow for biological uptake by phytoplankton and transfer up the food web. The soft coral Clavularia sp., the calcareous algae Halimeda sp., and the tunicate Polycarpa sp. collected from the hydrothermal area each displayed distinctly higher (up to 20 times) total arsenic compared to the control site, with increasing trends while approaching focused hydrothermal venting. Organic and inorganic arsenic species were extracted intact from the tissues of each organism, separated by anion exchange chromatography, and analyzed by inductively-coupled plasma-dynamic reaction cell-mass spectrometry. Overall, speciation patterns for Clavularia were similar for the control site versus the hydrothermal site, although the concentrations were much higher. Elevated concentrations of DMA and cationic forms of arsenic, most likely AB, in Clavularia, both from the control site and from the hydrothermal area suggest its metabolic pathway is not altered due to hydrothermal activity, and is similar to other marine organisms. Arsenic speciation patterns in Polycarpa were also similar for both sites, and suggests uptake of arsenic via food chain, containing neither As(III) nor As(V), but abundant excluded As and DMA. It is unclear if methylation is taking place within this organism or prior to ingestion. Elevated concentrations of As(III) in Halimeda from the hydrothermal system suggest this organism is not efficient at methylating inorganic arsenic.

Pichler, T.; Wallschläger, D.; Price, R. E.

2009-12-01

185

Megafaunal distribution and assessment of total methane and sulfide consumption by mussel beds at Menez Gwen hydrothermal vent, based on geo-referenced photomosaics  

NASA Astrophysics Data System (ADS)

The Menez Gwen hydrothermal vents, located on the flanks of a small young volcanic structure in the axial valley of the Menez Gwen seamount, are the shallowest known vent systems on the Mid-Atlantic Ridge that host chemosynthetic communities. Although visited several times by research cruises, very few images have been published of the active sites, and their spatial dimensions and morphologies remain difficult to comprehend. We visited the vents on the eastern flank of the small Menez Gwen volcano during cruises with RV Poseidon (POS402, 2010) and RV Meteor (M82/3, 2010), and used new bathymetry and imagery data to provide first detailed information on the extents, surface morphologies, spatial patterns of the hydrothermal discharge and the distribution of dominant megafauna of five active sites. The investigated sites were mostly covered by soft sediments and abundant white precipitates, and bordered by basaltic pillows. The hydrothermally-influenced areas of the sites ranged from 59 to 200 m2. Geo-referenced photomosaics and video data revealed that the symbiotic mussel Bathymodiolus azoricus was the dominant species and present at all sites. Using literature data on average body sizes and biomasses of Menez Gwen B. azoricus, we estimated that the B. azoricus populations inhabiting the eastern flank sites of the small volcano range between 28,640 and 50,120 individuals with a total biomass of 50 to 380 kg wet weight. Based on modeled rates of chemical consumption by the symbionts, the annual methane and sulfide consumption by B. azoricus could reach 1760 mol CH4 yr-1 and 11,060 mol H2S yr-1. We propose that the chemical consumption by B. azoricus over at the Menez Gwen sites is low compared to the natural release of methane and sulfide via venting fluids.

Marcon, Y.; Sahling, H.; Borowski, C.; dos Santos Ferreira, C.; Thal, J.; Bohrmann, G.

2013-05-01

186

Hydrothermal sediment alteration at a seafloor vent field: Grimsey Graben, Tjörnes Fracture Zone, north of Iceland  

NASA Astrophysics Data System (ADS)

An active seafloor hydrothermal system subjects the background sediments of the Grimsey Graben (Tjörnes Fracture Zone) to alteration that produces dissolution of the primary volcaniclastic matrix and replacement/precipitation of sulfides, sulfates, oxides, oxyhydroxides, carbonates and phyllosilicates. Three types of hydrothermal alteration of the sediment are defined on the basis of the dominant hydrothermal phyllosilicate formed: smectite, kaolinite, chlorite. The most common alteration is near-total conversion of the volcaniclastic material to smectite (95-116°C). The dominant smectite in the deepest sediments sampled is beidellite, which is replaced by montmorillonite and an intimate mixture of di- and tri-octahedral smectite up core. This gradual vertical change in smectite composition suggests an increase in the Mg supply upward, the result of sediment alteration by the ascending hydrothermal fluids mixing with descending seawater. The vertical sequence kaolinite ? kaolinite-smectite mixed-layer ? smectite from bottom to top of a core, as well as the distinct zonation across the veins (kaolinite in the central zone ? kaolinite-smectite in the rim), suggests hydrothermal transformation of the initially formed smectite to kaolinite through kaolinite-smectite mixed-layer (150-160°C). The cause of this transformation might have been an evolution of the fluids toward a slightly acidic pH or a relative increase in the Al concentration. Minor amounts of chamosite fill thin veins in the deepest sections of some cores. The gradual change from background clinochlore to chamosite across the veins suggests that chamosite replaces clinochlore as Fe is made available from hydrothermal dissolution of detrital Fe-containing minerals. The internal textures, REE distribution patterns and the mode of occurrence of another magnesian phyllosilicate, kerolite, suggest that this mineral is the primary precipitate in the hydrothermal chimneys rather than an alteration product in the sediment. Kerolite precipitated after and grew on anhydrite in the chimneys. Oxygen isotope ratios are interpreted to reflect precipitation of kerolite at temperatures of 302° to 336°C. It accumulated in the hydrothermal mounds following the collapse of the chimneys and subsequent dissolution of anhydrite, thereby forming highly permeable aquifer layers underlying the vent field. Some kerolite was redeposited in the near vent field sediments by turbidity flows. The altered sediments are depleted in Mn, Rb and Sr, and enriched in U, Mo, Pb, Ba, As, Bi, Sb, Ag, Tl and Ga, as a result of leaching and precipitation, respectively. Conservative elements (Ti, Zr, Hf, Sc, Cr, Nb and Sn) are depleted or enriched in the altered sediments because of passive (precipitation or leaching of other phases) rather than active (because of their mobility) processes.

Dekov, Vesselin; Scholten, Jan; Garbe-SchöNberg, Carl-Dieter; Botz, Reiner; Cuadros, Javier; Schmidt, Mark; Stoffers, Peter

2008-11-01

187

Physiological characteristics of Thiomicrospira sp. strain L-12 isolated from deep-sea hydrothermal vents  

SciTech Connect

Growth of the obligately chemolithotrophic Thiomicrospira sp. strain L-12, isolated from a hydrothermal vent at a depth of 2,550 m in the Galapagos Rift region, was optimal at pH 8 and required 200 mM Na/sup +/ and divalent ions (Ca/sup 2 +/ and Mg/sup 2 +/). The organism was microaerophilic and tolerated 300 ..mu..M sulfide without a decrease in the rate of CO/sub 2/ incorporation. Growth and CO/sub 2/ incorporation occurred within the temperature range of 10 to 35/sup 0/C, with both optimal at 25/sup 0/C. At the in situ pressure of 250 atm, the rate of CO/sub 2/ incorporation was reduced by 25% relative to that measured at 1 atm; it was entirely suppressed at 500 atm. The results of this physiological characterization suggest that Thiomicrospira sp. strain L-12 can be an active autotroph in the hydrothermal environment.

Ruby, E.G.; Jannasch, H.W.

1982-01-01

188

Effects of Hydrothermal Alteration on In-situ Physical Properties in an Active Hydrothermal Vent Field - First Results of log Interpretation in ODP Hole 1189B  

NASA Astrophysics Data System (ADS)

For the first time in the history of the Ocean Drilling Program (ODP), Leg 193 drilled into an active hydrothermal vent field associated with felsic magmatism at a convergent plate margin. The main scientific objectives were to study the subsurface volcanic architecture of the Pual ridge, delineate the structural and hydrologic characteristics of the PACMANUS active hydrothermal system, and understand the mineralization and alteration patterns associated with vigorous high temperature fluid flow. Due to low core recovery, downhole logs provide the only continuous records of in-situ physical properties with depth hence the logs are of prime importance for achieving the scientific objectives of the leg. Downhole and core measurements from three holes located in the high temperature Roman Ruins hydrothermal field (Site 1189) show intense hydrothermal alteration of dacites and rhyodacites and evidence of a mineralized stockwork zone. Downhole measurements from Hole 1189B show characteristic cyclic trends with electrical resistivity logs decreasing upwards. The upper parts of these cycles are characterized by increasing values of the photoelectric factor log, an indicator for the composition of the formation and slightly increased density values. The trends correlate with an increase in fracturing/brecciation observed in the electrical images of the FMS (Formation MicroScanner). However, higher values of density and photoelectric factor indicate an enrichment of heavier minerals in the upper parts of the cycles. Spectral gamma ray logs do not correlate with the cyclic variations in the resistivity logs. Uranium, a mobile element often used as indicator for alteration, gives a large contribution to the total gamma ray spectrum. Thus two different assemblages of logs may be used as indicator for alteration/mineralization in Hole 1189B. No correlation exists between the cyclic trends and the variations in the spectral gamma ray logs. This indicates that different alteration processes may be responsible for the cyclic trends and for the variations in the uranium log, respectively.

Bartetzko, A.; Iturrino, G. J.

2001-12-01

189

Abundant hydrothermal venting along melt-rich and melt-free ridge segments in the Lau back-arc basin  

NASA Astrophysics Data System (ADS)

The relationship between the spatial density of hydrothermal venting (ph) and spreading rate (us) is undefined along back-arc ridges. Here we report a continuous survey of hydrothermal plumes along the ~400-km-long Eastern Lau Spreading Center. The mean ph/us ratio for each of three tectonic segments followed the global midocean ridge trend, with ph doubling as us increased northward from 39 to 96 mm/yr. However, we found little correlation between ph and the previously imaged distribution of axial melt lenses, which are near-continuous along the southern two segments but wholly absent along the northernmost segment. We infer that venting on the southern segments is melt driven, whereas venting on the northern ELSC is entirely powered with heat extracted by deep circulation through hot rock. This segment may be a rare example of an entire fast-spreading segment where hydrothermal convection cells are powered by downward-migrating cracking fronts.

Baker, Edward T.; Resing, Joseph A.; Walker, Sharon L.; Martinez, Fernando; Taylor, Brian; Nakamura, Ko-ichi

2006-04-01

190

Population ecology of the tonguefish Symphurus thermophilus (Pisces; Pleuronectiformes; Cynoglossidae) at sulphur-rich hydrothermal vents on volcanoes of the northern Mariana Arc  

NASA Astrophysics Data System (ADS)

Flatfish are a major component of the hydrothermal vent community on three seamounts of the northern Mariana Volcanic Arc in the northwest Pacific. Nikko, Kasuga-2 and Daikoku seamounts host vent fields between 375 and 480 m depth where high temperature vents release molten sulphur. The small cynoglossid tonguefish, Symphurus thermophilus Munroe and Hashimoto, is ubiquitous in all vent habitats observed on these seamounts: among extensive fields of tubeworms and mussels and on solid sulphur surfaces on Nikko; on sulphur-rich sediments and barnacle-covered boulders on Kasuga-2; and on recent sulphur flows and on broad areas of loose and semi-consolidated sediments on Daikoku. We recorded repeated forays by individuals onto flows of molten sulphur as these surfaces cooled. Based on observations using ROVs, the mean density is 90 fish/m2 with maximum counts over 200 fish/m2 on Daikoku sediments. Compared to collected tonguefish from Daikoku and Kasuga-2, those from Nikko have significantly greater lengths and, on average, six times the mass. Otolith data indicate upper ages of 13 years with Nikko tonguefish growing significantly faster. Diets of tonguefish on the three seamounts reflect the different habitats and prey availability; in Daikoku specimens, small crustaceans and polychaetes are most common while on Nikko, gut contents are predominantly larger shrimp. We made the unusual observation of stunned midwater fish falling to the seafloor near the vents where S. thermophilus immediately attacked them. This tonguefish has a wide diet range and foraging behaviour that likely influence the differing growth rates and sizes of fish inhabiting the different vent sites. Limited genetic data suggest that larval exchange probably occurs among sites where the common habitat factor is high levels of elemental sulphur forming hard and partly unconsolidated substrata. Here, in the northern range of the Mariana Trench Marine National Monument, S. thermophilus, despite having an unusually broad habitat association, may be restricted in its overall range to this region of isolated volcanoes with active hydrothermalism.

Tunnicliffe, Verena; Tyler, Jennifer; Dower, John F.

2013-08-01

191

Formation of Zn and Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: implications for sulfide bioavailability to chemoautotrophs  

Microsoft Academic Search

BACKGROUND: The speciation of dissolved sulfide in the water immediately surrounding deep-ocean hydrothermal vents is critical to chemoautotrophic organisms that are the primary producers of these ecosystems. The objective of this research was to identify the role of Zn and Fe for controlling the speciation of sulfide in the hydrothermal vent fields at the Eastern Lau Spreading Center (ELSC) in

Heileen Hsu-Kim; Katherine M Mullaugh; Jeffrey J Tsang; Mustafa Yucel; George W Luther

2008-01-01

192

Dissolved Carbon Species in Diffuse and Focused Flow Hydrothermal Vents at the Main Endeavour Field, Northern Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

The magmatic and tectonic event of 1999 had a significant impact on the chemical composition of vent fluids issuing from the Main Endeavour Field (MEF), Juan de Fuca Ridge. Here, we report dissolved concentrations of H2, CO2, CO and C1-C3 alkanes measured in low and high-temperature hydrothermal fluids collected in August 2005 during an RV Atlantis/DSV Alvin expedition at MEF. In comparison with time series data, temperatures of the 2005 vent fluids were slightly lower than those recorded in the aftermaths of the tectonic event of 1999. The possible cooling of the hydrothermal subseafloor reaction zone is consistent with the observed increase in dissolved Cl to pre-1999 values. Converging compositional trends to pre-1999 conditions are also suggested for dissolved CO2 concentrations (~20 mmol/kg) in Puffer, Sully, Bastille and S&M vent fluids. In these focused flow and high-temperature vent fluids, dissolved CO2 is in thermodynamic equilibrium with CO(aq). The systematics of organic species in diffuse flow fluids, however, appears to be closely related to processes occurring within the near-seafloor environment. For example, excess CO(aq) observed in the diffuse flow fluids at Easter Island is attributed to sluggish CO- CO2(aq) equilibria at low temperatures, suggesting hydrothermal circulation of short-residence times. Short-lived hydrothermal circulation is further supported by the nearly identical C1/(C2+C3) ratios between focused and diffuse flow fluids. Furthermore, alkane distribution in the MEF diffuse flow fluids suggests direct mixing between seawater and hydrothermal fluid with minimal biological inputs, in contrast with the greater effect of microbial methanogenesis proposed in other ridge-crest hydrothermal environments. Thus, the coupling of CO2(aq)-CO(aq) redox equilibrium with dissolved carbon species in low- temperature vent fluids could provide a better understanding of the effect of subsurface microbial communities upon the composition of mid-ocean ridge hydrothermal fluids.

Foustoukos, D. I.; Seyfried, W. E.; Ding, K.; Pester, N. J.

2006-12-01

193

Colonization by pioneer populations of ?-Proteobacteria and community succession at mid-ocean ridge hydrothermal vents as determined by T-RFLP analysis  

NASA Astrophysics Data System (ADS)

Terminal-restriction fragment length polymorphism (T-RFLP) patterns were used to track populations of bacteria occurring within multiple bacterial growth chambers (BGCs) deployed at eight diffuse-flow (Tmax=78°C) hydrothermal vent orifices located within the caldera of Axial Volcano, Juan de Fuca Ridge. For comparison, two distal diffuse vents located at the Magic Mountain area on the Explorer Ridge were also examined. Over a five-year sampling period in conjunction with the NeMO (New Millennium Observatory) program, 52 BGCs were recovered after either a short-term (days) or long-term (annual) deployment. Upon recovery, genomic DNA was extracted and amplified using bacterial-specific PCR primers to generate 5' fluorescently-labeled amplicons of small subunit rRNA genes (i.e., SSU rDNAs). These PCR amplicons were digested with multiple tetrameric restriction endonucleases and the respective community diversity and succession patterns were characterized. The average number of populations (a measure of species richness) within the community that developed in short-term deployed BGCs was significantly lower than those detected in long-term deployed BGCs. All short-term BGC communities were dominated by primary colonizers or pioneer populations indicative of ?-Proteobacteria, of which, specific phylogenetic groups were recognized at vent sites throughout the five-year sampling period. The long-term BGCs showed evidence of successional events by an increased occurrence of numerous other populations accompanying the pioneer populations of ?-Proteobacteria. The discovery that all primary colonizing populations were most similar to known lineages of ?-Proteobacteria detected from hydrothermal vents located worldwide provides further evidence that a few cosmopolitan populations are capable of acting as the primary microbial successors of newly-formed hydrothermal vent systems.

Moyer, C. L.; Engebretson, J. J.

2002-12-01

194

High contents of hypotaurine and thiotaurine in hydrothermal-vent gastropods without thiotrophic endosymbionts.  

PubMed

Invertebrates at hydrothermal vents and cold seeps must cope with high levels of toxic H2S. In addition, these and all marine invertebrates must balance internal osmotic pressure with that of the ocean. Cells usually do so with organic osmolytes, primarily free amino acids (e.g., taurine, glycine) and methylamines (e.g., betaine). At vents and seeps, clams, mussels, and vestimentiferans with thiotrophic endosymbionts have high levels of hypotaurine and thiotaurine (a product of hypotaurine and HS-). These serve as osmolytes but their primary function may be to transport and/or detoxify sulfide; indeed, thiotaurine has been proposed to be a marker of thiotrophic symbiosis. To test this, we analyzed Depressigyra globulus snails and Lepetodrilus fucensis limpets from Juan de Fuca Ridge vents (1,530 m). Neither has endosymbionts, though the latter has thiotrophic ectosymbionts. Some specimens were rapidly frozen, while other live ones were kept in laboratory chambers, some with and others without sulfide. Non-vent gastropods from a variety of depths (2-3,000 m) were also collected. Tissues were analyzed for major osmolytes and taurine derivatives. The dominant osmolytes of non-vent snails were betaine in all species, and either taurine in shallow-living species or scyllo-inositol, glycerophosphorylcholine, and other amino acids in deep-sea species. In contrast, the dominant osmolytes were hypotaurine and betaine in D. globulus, and hypotaurine in L. fucensis. Both species had thiotaurine (as well as hypotaurine) at levels much greater than previously reported for vent and seep animals without endosymbionts. The ratio of thio- to thio- plus hypotaurine, a possible indicator of sulfide exposure, decreased in both species when kept in laboratory chambers with low or no sulfide, but stayed at high levels in snails kept with 3-5 mM sulfide. Thus, in some vent animals without endosymbionts, sulfide may be detoxified via conversion of hypotaurine to thiotaurine. The latter may be a marker of high sulfide exposure but not of thiotrophic endosymbionts. PMID:16788898

Rosenberg, Noah K; Lee, Raymond W; Yancey, Paul H

2006-08-01

195

Interaction of vent biota and hydrothermal deposits: Present evidence and future experimentation  

NASA Astrophysics Data System (ADS)

Actively-forming hydrothermal mineral deposits provide a source of energy for chemosynthesis and a substratum for colonization by adult and larval vent organisms. Since mineral deposition and organism growth can occur within similar time frames, their potential for interaction is substantial. The nature of this interaction is substantial. The nature of this interaction is the central theme of this paper. We review evidence for biological influences on deposit formation and destruction, and consider how the dynamics of sulfide chimney and mound growth may influence the distribution and composition of vent communities. Another theme that we develop concerns the mainly circumstantial nature of almost all evidence for biological-geological interaction. There exists very little experimental demonstration or solid statistical proof for links between biological or solid statistical proof for links between biological activity and mineral deposition processes at vents. This is not unusual for any new area of inquiry, particularly in a field that encompasses geological, chemical and biological data and observations. Indeed, these observations and ideas form the basis for suggestions for future experimental and field work. In order to encourage such experimentation, we discuss the types of evidence required to rigorously test the various hypothesis reviewed here.

Kim Juniper, S.; Sarrazin, Jozée

196

Genetic diversity and demographic instability in Riftia pachyptila tubeworms from eastern Pacific hydrothermal vents  

PubMed Central

Background Deep-sea hydrothermal vent animals occupy patchy and ephemeral habitats supported by chemosynthetic primary production. Volcanic and tectonic activities controlling the turnover of these habitats contribute to demographic instability that erodes genetic variation within and among colonies of these animals. We examined DNA sequences from one mitochondrial and three nuclear gene loci to assess genetic diversity in the siboglinid tubeworm, Riftia pachyptila, a widely distributed constituent of vents along the East Pacific Rise and Galápagos Rift. Results Genetic differentiation (FST) among populations increased with geographical distances, as expected under a linear stepping-stone model of dispersal. Low levels of DNA sequence diversity occurred at all four loci, allowing us to exclude the hypothesis that an idiosyncratic selective sweep eliminated mitochondrial diversity alone. Total gene diversity declined with tectonic spreading rates. The southernmost populations, which are subjected to superfast spreading rates and high probabilities of extinction, are relatively homogenous genetically. Conclusions Compared to other vent species, DNA sequence diversity is extremely low in R. pachyptila. Though its dispersal abilities appear to be effective, the low diversity, particularly in southern hemisphere populations, is consistent with frequent local extinction and (re)colonization events.

2011-01-01

197

Is the CH4, H2 and CO venting from submarine hydrothermal systems produced by thermophilic bacteria?  

Microsoft Academic Search

Submarine hydrothermal vents are a major source of methane to the oceans1,2. The methane, as well as H2 and CO, are generally believed to result from degassing of the mantle or from abiogenic water-rock reactions1, a conclusion supported by direct correlations between 3He and CH4, and generally between CH4, H2 and CO and dissolved silicate in hydrothermal waters2,3. An alternative

John A. Baross; Marvin D. Lilley; Louis I. Gordon

1982-01-01

198

Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (13 °N)  

Microsoft Academic Search

The mobility of rare-earth elements (REE) and U during hydrothermal alteration of the basalts at spreading centres has long been a matter of concern because of its bearing on the evolution and recycling of the oceanic crust1-6. Previous approaches to this problem have been indirect, through studies on altered dredged basalts or ophiolites. We report here sampling of hydrothermal vent

A. Michard; F. Albarède; G. Michard; J. F. Minster; J. L. Charlou

1983-01-01

199

Hydrothermal flow at Main Endeavour Field imaged and measured with Cable Operated Vent Imaging Sonar  

NASA Astrophysics Data System (ADS)

Initial acoustic monitoring of hydrothermal flow in the Main Endeavour Field (MEF) captures the spatial distribution of diffuse and focused discharge and shows potential for flux determinations. Our Cabled Observatory Vent Imaging Sonar (COVIS) was connected to the NEPTUNE Canada Endeavour Observatory in September 2010. Using a customized Reson 7125 multi-beam sonar, COVIS acquired a 29 day time series of black smoker plume and associated diffuse hydrothermal flow from Grotto, a 30 m diameter vent cluster in the MEF, Juan de Fuca Ridge. Detection of the spatial patterns of diffuse flow utilizes phase decorrelation of the acoustic signal (200kHz) by buoyancy-driven turbulence (acoustic scintillation) to produce a time series of maps. Substantial fluctuation in the detected diffuse flow area (0.1 - 18 m^2) was observed over the 29 days of observation, although position remained stable. Acoustic imaging of focused flow (400 kHz) utilizes high volume backscatter (attributed to particles and turbulent sound speed fluctuations) to image in 3D the initial tens of meters of rise of buoyant plumes. Spectral analysis of bending inclination of a strong plume from multiple fast smokers on the NW end of Grotto (north tower) indicates that the dominant modes correspond with the ambient mixed semi-diurnal tide (based on current meter data at a mooring 2.9 km to the north and on a tidal model), with at least one secondary mode attributable to sub-inertial flow related to inflow to the axial valley. A weaker plume from several slower smokers is present on the NE end of Grotto. On first analysis, the bending inclination of the weaker plume appears to be affected by the stronger plume. Quantification of flow velocity and volume flux of plumes begins with measuring the Doppler phase shift through plume cross-sections beginning at 5 m above source vents where discharge merges. The volume flux measurements enable calculation of entrainment coefficients, which prior work on the same strong plume indicated increase with degree of bending. The acoustic data in concert with in situ measurements support inversions to obtain fluxes to elucidate the role of hydrothermal flow in transfer of heat, chemicals and biological material from the crust to the ocean. We are exploring the feasibility of fitting plume models to Doppler velocity data in order to estimate heat flux. Ongoing analysis pursues quantification of fluid flux from diffuse and focused flow. In addition, the time series provide observations of hydrothermal flow response to tidal, tectonic and volcanic forcing on time scales from hours potentially to years. (Work supported by NSF Grants Nos. OCE-0824612 and OCE-0825088)

Rona, P. A.; Bemis, K. G.; Xu, G.; Jackson, D. R.; Jones, C. D.

2011-12-01

200

Comparative metagenomics of microbial communities inhabiting deep-sea hydrothermal vent chimneys with contrasting chemistries  

PubMed Central

Deep-sea hydrothermal vent chimneys harbor a high diversity of largely unknown microorganisms. Although the phylogenetic diversity of these microorganisms has been described previously, the adaptation and metabolic potential of the microbial communities is only beginning to be revealed. A pyrosequencing approach was used to directly obtain sequences from a fosmid library constructed from a black smoker chimney 4143-1 in the Mothra hydrothermal vent field at the Juan de Fuca Ridge. A total of 308?034 reads with an average sequence length of 227?bp were generated. Comparative genomic analyses of metagenomes from a variety of environments by two-way clustering of samples and functional gene categories demonstrated that the 4143-1 metagenome clustered most closely with that from a carbonate chimney from Lost City. Both are highly enriched in genes for mismatch repair and homologous recombination, suggesting that the microbial communities have evolved extensive DNA repair systems to cope with the extreme conditions that have potential deleterious effects on the genomes. As previously reported for the Lost City microbiome, the metagenome of chimney 4143-1 exhibited a high proportion of transposases, implying that horizontal gene transfer may be a common occurrence in the deep-sea vent chimney biosphere. In addition, genes for chemotaxis and flagellar assembly were highly enriched in the chimney metagenomes, reflecting the adaptation of the organisms to the highly dynamic conditions present within the chimney walls. Reconstruction of the metabolic pathways revealed that the microbial community in the wall of chimney 4143-1 was mainly fueled by sulfur oxidation, putatively coupled to nitrate reduction to perform inorganic carbon fixation through the Calvin–Benson–Bassham cycle. On the basis of the genomic organization of the key genes of the carbon fixation and sulfur oxidation pathways contained in the large genomic fragments, both obligate and facultative autotrophs appear to be present and contribute to biomass production.

Xie, Wei; Wang, Fengping; Guo, Lei; Chen, Zeling; Sievert, Stefan M; Meng, Jun; Huang, Guangrui; Li, Yuxin; Yan, Qingyu; Wu, Shan; Wang, Xin; Chen, Shangwu; He, Guangyuan; Xiao, Xiang; Xu, Anlong

2011-01-01

201

Impact of the Colonization by Paralvinella sulfincola on the Microbial Diversity Associated with a Deep-Sea Hydrothermal Vent Sulfide Chimney (Axial Seamount, Juan de Fuca Ridge)  

NASA Astrophysics Data System (ADS)

In the early stages of high temperature deep-sea hydrothermal vent chimneys growth, the walls remain porous and allow the escape of hydrothermal fluids as well as an inflow of seawater. This gradual mixing creates sharp thermal and geochemical gradients and provides potential habitats for physiologically diverse microorganisms. The annelid polychaete Paralvinella sulfincola colonizes the external surfaces of these structures, covering them with layered mucous tubes that locally alter the mixing of discharged hydrothermal fluids and surrounding seawater. Modifications of the physical and chemical conditions combined with an accumulation of elemental sulfur (S0) in P. sulfincola mucous tube are thought to be responsible for the deposition of a thin marcassite (FeS2) crust on outer surfaces of anhydrite chimneys (Juniper et al. 1992). This marcassite deposition could partly be induced by a shift in the composition of microbial communities that would to be locally associated with the presence of P. sulfincola. To test this hypothesis, we evaluated the impact of the colonization by P. sulfincola on the microbial communities present at the surface of an active sulfide chimney. Bacterial and archaeal 16S rRNA genes were amplified from DNA extracted from a P. sulfincola tube and from a chimney mineral sample. Using the statistical analysis demonstrated by Singleton et al. (2001), both clone libraries from the chimney sample have been shown to be significantly different from those of the P. sulfincola tube sample, even though the major phylogenetic groups of these libraries were similar. As it has been observed at other deep-sea hydrothermal vent sites, the Epsilon-Proteobacteria and the Deep-sea Hydrothermal Vent Euryarchaeotic Group 1 were the dominant components of both bacterial and archaeal clone libraries. These results seem to indicate that P. sulfincola affect the microbial community composition on high temperature chimneys.

Page, A.; Juniper, K.; Olagnon, M.; Alain, K.; Desrosiers, G.; Querellou, J.; Cambon-Bonavita, M.

2002-12-01

202

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

USGS Publications Warehouse

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.

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

2008-01-01

203

Assessing the influence of physical, geochemical and biological factors on anaerobic microbial primary productivity within hydrothermal vent chimneys.  

PubMed

Chemosynthetic primary production supports hydrothermal vent ecosystems, but the extent of that productivity and its governing factors have not been well constrained. To better understand anaerobic primary production within massive vent deposits, we conducted a series of incubations at 4, 25, 50 and 90 °C using aggregates recovered from hydrothermal vent structures. We documented in situ geochemistry, measured autochthonous organic carbon stable isotope ratios and assessed microbial community composition and functional gene abundances in three hydrothermal vent chimney structures from Middle Valley on the Juan de Fuca Ridge. Carbon fixation rates were greatest at lower temperatures and were comparable among chimneys. Stable isotope ratios of autochthonous organic carbon were consistent with the Calvin-Benson-Bassham cycle being the predominant mode of carbon fixation for all three chimneys. Chimneys exhibited marked differences in vent fluid geochemistry and microbial community composition, with structures being differentially dominated by gamma (?) or epsilon (?) proteobacteria. Similarly, qPCR analyses of functional genes representing different carbon fixation pathways showed striking differences in gene abundance among chimney structures. Carbon fixation rates showed no obvious correlation with observed in situ vent fluid geochemistry, community composition or functional gene abundance. Together, these data reveal that (i) net anaerobic carbon fixation rates among these chimneys are elevated at lower temperatures, (ii) clear differences in community composition and gene abundance exist among chimney structures, and (iii) tremendous spatial heterogeneity within these environments likely confounds efforts to relate the observed rates to in situ microbial and geochemical factors. We also posit that microbes typically thought to be mesophiles are likely active and growing at cooler temperatures, and that their activity at these temperatures comprises the majority of endolithic anaerobic primary production in hydrothermal vent chimneys. PMID:23551687

Olins, H C; Rogers, D R; Frank, K L; Vidoudez, C; Girguis, P R

2013-03-29

204

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)

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.

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

2011-12-01

205

Ultrastructure of the gill of the hydrothermal vent bivalve Calyptogena magnifica , with a discussion of its nutrition  

Microsoft Academic Search

Calyptogena magnifica Boss and Turner, 1980, a new Vesicomyidae found during the Galápagos expedition in hydrothermal vents of the East Pacific Rise, was collected in the same Rise at 21°N during the “Oasis” expedition (March 1982), and samples of the gill were fixed for ultrastructural observations. The large size and structure of the gill indicate that this is the organ

A. Fiala-Médioni; C. Métivier

1986-01-01

206

Draft Genome of Pseudomonas stutzeri Strain NF13, a Nitrogen Fixer Isolated from the Galapagos Rift Hydrothermal Vent  

PubMed Central

Pseudomonas stutzeri strain NF13 was isolated from a water sample taken at a hydrothermal vent in the Galapagos rift. It was selected for its ability to metabolize sulfur compounds and to grow diazotrophically. Here, we report the first draft genome of a member of genomovar 19 of the species.

Pena, Arantxa; Busquets, Antonio; Gomila, Margarita; Mayol, Joan; Bosch, Rafael; Nogales, Balbina; Garcia-Valdes, Elena; Bennasar, Antonio

2013-01-01

207

Draft Genome of Pseudomonas stutzeri Strain NF13, a Nitrogen Fixer Isolated from the Galapagos Rift Hydrothermal Vent.  

PubMed

Pseudomonas stutzeri strain NF13 was isolated from a water sample taken at a hydrothermal vent in the Galapagos rift. It was selected for its ability to metabolize sulfur compounds and to grow diazotrophically. Here, we report the first draft genome of a member of genomovar 19 of the species. PMID:23516224

Peña, Arantxa; Busquets, Antonio; Gomila, Margarita; Mayol, Joan; Bosch, Rafael; Nogales, Balbina; García-Valdés, Elena; Bennasar, Antonio; Lalucat, Jorge

2013-03-21

208

The Oxygen Isotope Composition of PO4 Extracted From Lost City Hydrothermal Vents -- a Potential Biosignature for Vent Hosted Microbial Ecosystems  

NASA Astrophysics Data System (ADS)

The oxygen isotope composition of phosphate is a useful indicator of biological P cycling in low to moderate temperature environments, such as those that characterize most of the habitable zone of Earth. In microbially active systems, phosphate oxygen isotope compositions are driven towards a temperature- dependent, thermodynamic equilibrium offset from water. Enzymatic reactions involving organophosphorus compounds, pyrophosphate, and polyphosphates promote the exchange of oxygen atoms between water and phosphate. These enzyme driven reactions are key to the attainment of isotopic equilibrium under conditions in which the rate of inorganic oxygen exchange is slow. We have examined the phosphate oxygen isotope systematics of the Lost City hydrothermal vent system, which is located on a gabbroic and peridotitic massif, 15km off-axis of the Mid Atlantic Ridge. The Lost City hydrothermal system's fluid chemistry and heat budget are controlled by serpentinization reactions. Fluids vent at temperatures up to around 80°C and with a pH around 9-10. Vent mineralogy is dominated by calcite, aragonite, and brucite, with mineral layers intercalated by biofilms. Phosphorus content ranges from 400 - 1000 ppm (by mass as P2O5) in the vent samples we have analyzed. The oxygen isotope composition of phosphate extracted from the vent solids is a few per mil lighter than that of phosphate dissolved in ambient sea water. This oxygen isotope composition reflects exchange of phosphate oxygen with water oxygen at elevated temperature. We show that under a wide range of conditions, abiological reaction rates are too slow to produce these isotopic compositions. This suggests that cycling of the phosphate by the vent system's microbial community has imprinted the phosphate with a stable isotope signature of biological activity. The oxygen isotope composition of lattice-bound phosphate preserves well in the geologic record, commending phosphate oxygen isotope measurements as a tool for the detection of life in ancient terrestrial and in extraterrestrial rocks.

Robinson, K. L.; Kelley, D. S.; Fogel, M. L.; Colman, A. S.

2008-12-01

209

Characterization of a Novel Thermococcus sp. from a Hydrothermal Vent of the Suiyo Seamount  

NASA Astrophysics Data System (ADS)

The Suiyo seamount is located at 210 km north-northwest of Chichijima Island of the Izu-Bonin Arc. The hydrothermal vents of the Suiyo seamount discharges hot water as high as 308 degrees. We obtained a novel Thermococcus sp. from the hydrothermal vent and partially characterized it. The Thermococcus sp. was observed as usual coccus in initial stages of culture, but changed to transparent cells, within which one or a few spots exist. In the present study, the process of the alteration of the appearance was studied. Materials and Methods: Hot water (maximum temperature of 100 degrees) from a hydrothermal vent of Suiyo seamount was filtrated with a Nuclepore filter (pore size 0.2 micro m) on a research vessel. The filter was brought back to the laboratory, being kept at ?20 degrees, and inoculated into the Thermococcus medium (JCM280, pH 7.0) under anaerobic conditions (nitrogen:hydrogen:carbon dioxide=80:10:10). This was cultured at 80 degrees. For observation by fluorescent microscopy, fluorescent dyes Live/Dead (Molecular Probes) were used. Results and Discussion: The Thermococcus sp. was purified by a series of dilutions to extinction. Analysis of 16S rDNA indicated that this organism belongs to Thermococcus, showing the highest homology of 99.5 percent with T. sulfurophilus. This organism showed a peculiar characteristic; in growth curve, the cell density once declined in an early stage of growth, and then, increased again. We took the culture at the point of the first peak and saw it by phase contrast microscopy. Some cells are singular, but the others are in pairs. Surprisingly, the paired cells fused in 1 h under microscopic observation, which could explain the decline in the growth curve. The steady state of the coccus was very short, and it soon changed to transparent cells, which looked transparent under phase contrast microscopy, and within which one or a few spots exist. These spot green-fluoresced under fluorescent microscopy with Live/Dead. This finding suggests that the transparent cells are live and the spots contain DNA. The possibility that the spots represent spores is discussed; there have been no reports of spores of Thermococcus.

Kuwabara, T.; Minaba, M.; Iwayama, Y.; Saida, H.; Kamekura, M.; Sakaushi, S.; Maruyama, A.; Ishibashi, J.; Inoue, I.

2002-12-01

210

A modeling approach of the influence of local hydrodynamic conditions on larval dispersal at hydrothermal vents.  

PubMed

Deep-sea hydrothermal vent animal communities along oceanic ridges are both patchy and transient. Larval dispersal is a key factor in understanding how these communities function and are maintained over generations. To date, numerical approaches simulating larval dispersal considered the effect of oceanic currents on larval transportation over hundreds of kilometers but very seldom looked at the effect of local conditions within meters around chimneys. However, small scale significant variations in the hydrodynamics may influence larval fate in its early stages after release, and hence have a knock-on effect on both dispersal and colonization processes. Here we present a new numerical approach to the study of larval dispersal, considering small scales within the range of the biological communities, called "bio-hydrodynamical" scale, and ranging from a few centimeters to a few meters around hydrothermal sources. We use a physical model for the vent based on jet theory and compute the turbulent velocity field around the smoker. Larvae are considered as passive particles whose trajectories are affected by hydrodynamics, topography of the vent chimney and larval biological properties. Our model predicts that bottom currents often dominate all other factors either by entraining all larvae away from the vent or enforcing strong colonization rates. When bottom currents are very slow (<1 mms(-1)), general larvae motion is upwards due to entrainment by the main smoker jet. In this context, smokers with vertical slopes favor retention of larvae because larval initial trajectory is nearly parallel to the smoker wall, which increases the chances to settle. This retention phenomenon is intensified with increasing velocity of the main smoker jet because entrainment in the high velocity plume is preceded by a phase when larvae are attracted towards the smoker wall, which occurs earlier with higher velocity of the main jet. Finally, the buoyancy rate of the larvae, measured to be in the range of 0.01 mms(-1), is generally irrelevant unless hydrodynamic conditions are balanced, i.e. if the buoyancy rate is comparable to both the bottom current speed and the local water velocity due to entrainment by close smokers. Overall, our model evidences the strong effect of the release point of larvae on their future entrainment within local fluxes. Larvae released from smoker walls might have an entirely different fate than those released further away in the water column. The latter are not, or less, affected by near-chimney hydrodynamics. PMID:18834891

Bailly-Bechet, Marc; Kerszberg, Michel; Gaill, Françoise; Pradillon, Florence

2008-08-27

211

Quantitative Population Analysis of Some Groups of Epsilon-Proteobacteria, Using in situ Growth Chamber Samples From Hydrothermal Vents in the South Mariana  

NASA Astrophysics Data System (ADS)

To reveal deep-sea hydrothermal microbial ecosystems, we have developed and applied several new sampling systems, e.g., in situ filter samplers and in situ growth chambers. The later enables to incubate and accumulate microbes inside a hydrothermal vent with complex physico-chemical gradients naturally created in a vent flow. Using this system, we have found several novel phylotypes of microbes in the Suiyo Seamount. Among them, two novel groups of epsilon-Proteobacteria (SSSV-BE1 and SSSV-BE2; Higashi et al. FEMS-ME 2004) were assumed to originate from sub-vent fields, mainly at the borehole SH-APSK05. Some of the known epsilon groups, i.e., CorreOs Groups D (the hydrothermal vent type) and Group B (the microbial mat type), were also detected in the same samples. Afterwards, we have further improved in situ growth chambers larger to gain enough amounts of microbial RNA samples for quantitative population analyses. A new chamber system named column-II type was then applied to a natural vent at Fryer site in the Mariana Trough, with temperatures of venting fluids beyond 109 C. Through the 16S rRNA gene clone library analysis, members of the above epsilon-Proteobacteria groups were frequently found in this column-II chamber sample, as well as the Suiyo Seamout samples. So, we tried to estimate population sizes of these epsilons by a quantitative fluorescent dot-blot hybridization (FDBH) technique. First, we newly designed two novel oligonucleotide probes specific to members of the groups D (26 mer) and SSSV-BE1 (23 mer), in which the stringency was checked using soft wares from Ribosomal Database Project II and DDBJ. Total RNA samples, after extracted and purified from the chamber samples, were applied to a nylon membrane filter and hybridized with these two specific probes, as well as Eubacteria, Universal, and some sub-domain/group-specific probes. After the hybridization, resulting fluorescence intensities were quantified, averaged, and compared each other, and then the target microbial population was calculated. Finally, we estimated the relative abundance of these epsilon-Proteobacteria groups in the total Bacteria, and the results implied that more SSSV-BE and group D exist as it goes to the deeper sub-vent. Further examinations of the population, and of whether this phenomenon can be observed commonly such as from the Suiyo Seamount samples, are carried out at the moment.

Miyako, C.; Higashi, Y.; Maruyama, A.

2004-12-01

212

Retinal anatomy of Chorocaris chacei, a deep-sea hydrothermal vent shrimp from the Mid-Atlantic Ridge.  

PubMed

Exploration of deep-sea hydrothermal vents over the past quarter century has revealed that they support unique and diverse biota. Despite the harsh nature of the environment, vents along the Mid-Atlantic Ridge are dominated by large masses of highly motile Bresiliid shrimp. Until 1989, when it was discovered that the vent shrimp Rimicaris exoculata possesses a hypertrophied dorsal eye, many believed that animals populating hydrothermal vents were blind. Chorocaris chacei (originally designated Rimicaris chacei) is a Bresiliid shrimp found at hydrothermal vent fields along the Mid-Atlantic Ridge. Like R. exoculata, C. chacei has a hypertrophied retina that appears to be specialized to detect the very small amount of light emitted from the orifices of black smoker hydrothermal vent chimneys. C. chacei lacks the sophisticated compound eyes common to other decapod crustaceans. Instead, it has a smooth cornea, with no dioptric apparatus, apposed by a tightly packed, massive array of photosensitive membrane. Photoreceptors in the C. chacei retina are segmented into a hypertrophied region that contains the photosensitive membrane and an atrophied cell body that is roughly ten times smaller in volume than the photosensitive segment. The microvillar photosensitive membrane is consistent in structure and ultrastructure with the rhabdoms of decapod and other invertebrate retinas. However, the volume density of photosensitive membrane (> or =60%) exceeds that typically observed in invertebrate retinas. The reflecting pigment cells commonly found in decapod retinas are represented in the form of a matrix of white diffusing cells that exhibit Tyndall scattering and form an axial sheath around the photoreceptors. All photoreceptor screening pigment granules and screening pigment cells are restricted to the region below the photoreceptor nuclei and are thereby removed from the path of incident light. No ultrastructural evidence of rhythmic cycling of photosensitive membrane was observed. The morphological adaptations observed in the C. chacei retina suggest that it is a high-sensitivity photodetector that is of functional significance to the animal. PMID:9302103

Lakin, R C; Jinks, R N; Battelle, B A; Herzog, E D; Kass, L; Renninger, G H; Chamberlain, S C

1997-09-01

213

Geological context and vents morphology of the ultramafic-hosted Ashadze hydrothermal areas (Mid-Atlantic Ridge 13°N)  

NASA Astrophysics Data System (ADS)

Recent ROV dives and high-resolution bathymetric data acquired over the Ashadze fields on the Mid-Atlantic Ridge (13°N) allow us to derive constraints on the regional and local geological setting of ultramafic-hosted hydrothermal fields. The active vent fields of Ashadze hydrothermal fields are located in the western axial valley wall, downslope from the termination of a prominent corrugated surface and in a transitional domain with respect to ridge segmentation. The study of the shipboard and ROV bathymetry shows that decameter (100 m by 60 m) to kilometer-scaled rockslides shape the axial valley wall slopes in this region. The Ashadze 1 vent field occurs on a coherent granular landslide rock mass that is elongated in an E-W direction. The Ashadze 1 vent field comprises hundreds of active and inactive sulfide chimneys. The Ashadze 2 vent field is located in a NNE-trending linear depression which separates outcrops of gabbros and serpentinized peridotites. Active black smokers in the Ashadze 2 field are located on ultramafic substratum in a 40-m diameter crater, 5-m deep. This crater recalls similar structures described at some vents of the Logatchev hydrothermal field (Mid-Atlantic Ridge 15°N). We discuss the mode of formation for these craters, as well as that for a breadcrust-like array of radial fissures identified at Ashadze 1. We propose that hydrothermalism at Ashadze can be an explosive phenomena associated with geyser-like explosions. Our study also constrains the geological and geophysical context of the ultramafic-hosted Ashadze hydrothermal system that may use the oceanic detachment fault as a preferred permeability conduit.

OndréAs, HéLèNe; Cannat, Mathilde; Fouquet, Yves; Normand, Alain

2012-11-01

214

Calibration of an acoustic system for measuring 2-D temperature distribution around hydrothermal vents.  

PubMed

One of the fundamental purposes of quantitative acoustic surveys of seafloor hydrothermal vents is to measure their 2-D temperature distributions. Knowing the system latencies and the acoustic center-to-center distances between the underwater transducers in an acoustic tomography system is fundamental to the overall accuracy of the temperature reconstruction. However, commercial transducer sources typically do not supply the needed data. Here we present a novel calibration algorithm to automatically determine the system latencies and the acoustic center-to-center distances. The possible system latency error and the resulting temperature error are derived and analyzed. We have also developed the experimental setup for calibration. To validate the effectiveness of the proposed calibration method, an experimental study was performed on acoustic imaging of underwater temperature fields in Lake Qiezishan, located at Longling County, Yunnan Province, China. Using the calibrated data, the reconstructed temperature distributions closely resemble the actual distributions measured with thermocouples, thus confirming the effectiveness of our algorithm. PMID:23375572

Fan, Wei; Chen, Chen-Tung Arthur; Chen, Ying

2013-01-21

215

Phylogenetic diversity of methanogenic, sulfate-reducing and methanotrophic prokaryotes from deep-sea hydrothermal vents and cold seeps  

NASA Astrophysics Data System (ADS)

Microbial communities of methanogenic, sulfate-reducing and methanotrophic prokaryotes from deep-sea environments were investigated by molecular phylogenetic analysis of the deduced amino acid sequences of the genes encoding for the methyl coenzyme M reductase ( mcrA), dissimilatory sulfite reductase ( dsrAB) and particulate methane monoxygenase ( pmoA), respectively. Clone libraries of PCR amplified genes were constructed using DNA extracted from deep-sea vent chimneys (Rainbow and Logatchev hydrothermal vent fields, Mid-Atlantic Ridge, Atlantic Ocean; 9°N East Pacific Rise, Pacific Ocean) and from vertically subsampled sediment cores from cold-seep areas (Blake Ridge, western Atlantic Ocean; Florida Escarpment, Gulf of Mexico). Recombinant clones were screened by RFLP and representative dsrAB, mcrA and pmoA genes were sequenced. The dsrAB sequences grouped primarily within the orders Desulfobacterales, Syntrophobacterales and the Gram-positive order Clostridales. Cold-seep mcrA sequences were distributed among the ANME-2c, -2d and -2e groups, which were previously shown to be associated with the anaerobic oxidation of methane. This study also reports the first mcrA sequences from a high-temperature, black smoker chimney (Logatchev) to group within the ANME-2e subgroup. The majority of the remaining hydrothermal vent mcrA sequences were primarily related to thermophilic members of the anaerobic, methanogenic order Methanococcales. A shift in the dominant ANME-2 group with depth in the sediment for both Florida Escarpment and Blake Ridge mcrA libraries was detected. ANME-2d related clones were detected in the top zones of both cores, with the frequency of ANME-2e related clones increasing with depth. All pmoA sequences retrieved from the cold-seep sites were found to be related to Type I methanotrophic members of the ?-proteobacteria, and were primarily distributed among three major clusters of sequences. No Type II pmoA sequences related to methanotrophic members of the ?-proteobacteria were detected, suggesting that the methanotrophic communities in these cold-seep areas are dominated by Type I ?-proteobacteria.

Reed, Andrew J.; Dorn, Ruth; Van Dover, Cindy L.; Lutz, Richard A.; Vetriani, Costantino

2009-09-01

216

Mineralized iron oxidizing bacteria from hydrothermal vents: targeting biosignatures on Mars  

NASA Astrophysics Data System (ADS)

Putative hydrothermal systems have been identified on Mars based on orbital imagery and rover-based analyses. Based on Earth analogs, hydrothermal systems on Mars would be highly attractive for their potential for preserving organic and inorganic biosignatures. For example, iron oxidizing bacteria are ubiquitous in marine and terrestrial hydrothermal systems, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Microfossils of iron oxidizing bacteria have been found in ancient Si-Fe deposits and iron oxidation may be an ancient and widespread metabolic pathway. In order to investigate mineralized iron oxidizing bacteria as a biosignature, we have examined samples collected from extinct hydrothermal vents along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic iron oxidizing bacteria, isolated from active Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and O2 concentration (5%) in a controlled bioreactor system. Samples and experimental products were examined with a combination of variable-pressure and field-emission scanning electron microscopy (SEM), in some cases by preparing samples with a focused ion beam (FIB) milling system. Light-toned seafloor samples display abundant filamentous forms resembling, in both size and shape (1-5 microns in diameter and up to several microns in length), the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Some samples consist entirely of low-density masses of silica (>90% Si) encrusted filamentous forms. The presence of unmineralized filamentous matter rich in C and Fe suggests that these are the remains of iron oxidizing bacteria. Mineralized filaments sectioned by FIB show variable internal material within semi-hollow, tubular-like features. Silica encrustations also show pseudo-concentric growth bands. In the bioreactor runs, abundant microbial growth and formation of an iron oxyhydroxide precipitate, either in direct association with the cells or within the growth medium, were observed. Preliminary analyses suggest that these precipitates are different from abiotic precipitates. Continuing work includes high-resolution TEM observations of cultured organisms and biogenic iron minerals, Raman and reflectance spectroscopy of precipitates, examination of seafloor incubation experiments, and bioreactor silicification experiments in order to better understand the Fe-Si fossilization process. Microaerophilic iron oxidation could have existed on the early Earth in environments containing small amounts of oxygen produced either by locally-concentrated photosynthetic microorganisms (e.g., cyanobacteria) or by chemical reactions. By analogy, similar subsurface or near-surface microaerophilic environments could have existed on Mars in the past, including in low-temperature hydrothermal systems. The distinctive morphologies and Fe-Si mineralization patterns of iron oxidizing bacteria could be a useful biosignature to search for on Mars. Deposits and features similar to those described here could be identified on Mars with existing technologies, and thus hydrothermal systems represent an attractive target for future surface and sample return missions.

Leveille, R. J.

2010-12-01

217

Distribution and composition of hydrothermal plume particles from the ASHES vent field at Axial Volcano, Juan de Fuca Ridge. [Axial Seamount Hydrothermal Emission Study  

SciTech Connect

In 1986 and 1987, buoyant and neutrally buoyant hydrothermal plume particles from the ASHES vent field within Axial Volcano were sampled to study their variations in composition with height above the seafloor. Individual mineral phases were identified using standard X ray diffraction procedures. Elemental composition and particle morphologies were determined by X ray fluorescence spectrometry and scanning electron microscopy/X ray energy spectrometry techniques. The vent particles were primarily composed of sphalerite, anhydrite, pyrite, pyrrhotite, chalcopyrite, barite, hydrous iron oxides, and amorphous silica. Grain size analyses of buoyant plume particles showed rapid particle growth in the first few centimeters above the vent orifice, followed by differential sedimentation of the larger sulfide and sulfate minerals out of the buoyant plume. The neutrally buoyant plume consisted of a lower plume, which was highly enriched in Fe, S, Zn, and Cu, and an upper plume, which was highly enriched in Fe and Mn. The upper plume was enriched in Fe and Mn oxyhydroxide particles, and the lower plume was enriched in suspended sulfide particles in addition to the Fe and Mn oxyhydroxide particles. The chemical data for the water column particles indicate that chemical scavenging and differential sedimentation processes are major factors controlling the composition of the dispersing hydrothermal particles. Short-term sediment trap experiments indicate that the fallout from the ASHES vent field is not as large as some of the other vent fields on the Juan de Fuca Ridge.

Feely, R.A.; Geiselman, T.L.; Baker, E.T.; Massoth, G.J. (NOAA, Seattle, WA (United States)); Hammond, S.R. (NOAA, Newport, OR (United States))

1990-08-10

218

Phylogenetic characterization of episymbiotic bacteria hosted by a hydrothermal vent limpet (lepetodrilidae, vetigastropoda).  

PubMed

Marine invertebrates hosting chemosynthetic bacterial symbionts are known from multiple phyla and represent remarkable diversity in form and function. The deep-sea hydrothermal vent limpet Lepetodrilus fucensis from the Juan de Fuca Ridge complex hosts a gill symbiosis of particular interest because it displays a morphology unique among molluscs: filamentous bacteria are found partially embedded in the host's gill epithelium and extend into the fluids circulating across the lamellae. Our objective was to investigate the phylogenetic affiliation of the limpet's primary gill symbionts for comparison with previously characterized bacteria. Comparative 16S rRNA sequence analysis identified one ?- and three ?-Proteobacteria as candidate symbionts. We used fluorescence in situ hybridization (FISH) to test which of these four candidates occur with the limpet's symbiotic gill bacteria. The ?-proteobacterial probes consistently hybridized to the entire area where symbiotic bacteria were found, but fluorescence signal from the ?-proteobacterial probes was generally absent. Amplification of the ?-proteobacterial 16S rRNA gene using a specific forward primer yielded a sequence similar to that of limpets collected from different ridge sections. In total, direct amplification or FISH identified a single ?-proteobacterial lineage from the gills of 23 specimens from vents separated by a distance up to about 200 km and collected over the course of 2 years, suggesting a highly specific and widespread symbiosis. Thus, we report the first filamentous ?-proteobacterial gill symbiont hosted by a mollusc. PMID:21551448

Bates, Amanda E; Harmer, Tara L; Roeselers, Guus; Cavanaugh, Colleen M

2011-04-01

219

Parasitization of a hydrothermal vent limpet (Lepetodrilidae, Vetigastropoda) by a highly modified copepod (Chitonophilidae, Cyclopoida).  

PubMed

The limpet Lepetodrilus fucensis McLean is very abundant at hydrothermal vents on the Juan de Fuca and Explorer Ridges in the northeast Pacific Ocean. This limpet is parasitized by an undescribed chitonophilid copepod throughout the limpet's range. The parasite copepodite enters the mantle cavity and attaches to the afferent branchial vein. The initial invasive stage is a vermiform endosome within the vein that develops an extensive rootlet system causing an enlargement of the afferent branchial vein. Subsequently, an ectosomal female body grows outside the vein to sizes up to 2 mm in width. Once a dwarf male attaches, egg clusters form and nauplii are released. In over 3000 limpets examined from 30 populations, prevalence averaged about 5% with localized infections in female limpets over 25%. After the establishment of limpet populations at new vents, copepod prevalence increased over the succeeding months to 3 years. Host effects were marked and included castration of both sexes and deterioration in gill condition which affected both food acquisition and the gill symbiont. There was a significantly greater parasite prevalence in larger females which likely modifies the reproductive and competitive success of local host populations. PMID:18664307

Tunnicliffe, V; Rose, J M; Bates, A E; Kelly, N E

2008-07-29

220

Characterization of large, autotrophic Beggiatoa spp. abundant at hydrothermal vents of the Guaymas Basin  

SciTech Connect

Filamentous bacteria, identified as members of the genus Beggiatoa by gliding motility and internal globules of elemental sulfur, occur in massive aggregations at the deep-sea hydrothermal vents of the Guaymas Basin, Gulf of California. Cell aggregates covering the surface of sulfide-emanating sediments and rock chimneys were collected by DS R/V Alvin and subjected to shipboard and laboratory experiments. Each sample collected contained one to three discrete width classes of this organism usually accompanied by a small number of flexibacteria (width, 1.5 to 4 {mu}m). The average widths of the Beggiatoa classes were 24 to 32, 40 to 42, and 116 to 122 {mu}m. As indicated by electron microscopy and cell volume/protein ratios, the dominant bacteria are hollow cells, i.e., a thin layer of cytoplasm surrounding a large central liquid vacuole. Activities of Calvin-cycle enzymes indicated that at least two of the classes collected possess autotrophic potential. Judging from temperature dependence of enzyme activities and whole-cell CO{sub 2} incorporation, the widest cells were mesophiles. The narrowest Beggiatoa sp. was either moderately thermophilic or mesophilic with unusually thermotolerant enzymes. This was consistent with its occurrence on the flanks of hot smoker chimneys with highly variable exit temperatures. In situ CO{sub 2} fixation rates, sulfide stimulation of incorporation, and autoradiographic studies suggest that these Beggiatoa spp. contribute significantly as lithoautrophic primary producers to the Guaymas Basin vent ecosystems.

Nelson, D.C. (Univ. of California, Davis (USA)); Wirsen, C.O.; Jannasch, H.W. (Woods Hole Oceanographic Institution, MA (USA))

1989-11-01

221

Study of Hydrothermal Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico  

Microsoft Academic Search

A shallow (30 ft) hydrothermal site named ``Cora'' (after the indigenous people thereby) was surveyed and sampled throughout direct observation with SCUBA diving during November 25 to December 4, 2000. A total of 10 dives were conducted in order to obtain representative samples from an 85oC fluid source of approximately 10 cm in diameter. Inherent difficulties to the sampling, such

A. Ortega-Osorio; R. M. Prol-Ledesma; A. G. Reyes; M. A. Rubio-Ramos; M. A. Torres-Vera

2001-01-01

222

Insights into tide-related variability at seafloor hydrothermal vents from time-series temperature measurements  

Microsoft Academic Search

Thermocouple\\/thermistor array packages and an in situ gamma detector were deployed in 1994 at two vent sites on the northern Cleft Segment of the Juan de Fuca Ridge. Continuous records of fluid temperatures were obtained in four separate locations over a period of 5.5 months, and these data were supplemented by current meter observations made ~2.5 km to the south

Margaret Kingston Tivey; Albert M. Bradley; Terrence M. Joyce; David Kadko

2002-01-01

223

Insights into tide-related variability at seafloor hydrothermal vents from time-series temperature measurements  

Microsoft Academic Search

Thermocouple\\/thermistor array packages and an in situ gamma detector were deployed in 1994 at two vent sites on the northern Cleft Segment of the Juan de Fuca Ridge. Continuous records of fluid temperatures were obtained in four separate locations over a period of 5.5 months, and these data were supplemented by current meter observations made ?2.5 km to the south

Margaret Kingston Tivey; Albert M. Bradley; Terrence M. Joyce; David Kadko

2002-01-01

224

Microearthquakes Beneath the Endeavour Hydrothermal Vent Fields: Insights Into Reaction Zone Processes  

NASA Astrophysics Data System (ADS)

From 2003-2006, a novel seismic network comprising seven short-period corehole seismometers and a broadband Guralp CMG-1T OBS was deployed using remotely operated vehicles in a subseafloor configuration on the Endeavour segment of the Juan de Fuca mid-ocean ridge. The seismic monitoring array was one part of a multi-disciplinary prototype NEPTUNE experiment designed to investigate the linkages between seismic deformation, hydrothermal fluxes, and microbial productivity along oceanic plate boundaries. The seismic network recorded high-quality data that illustrate the advantages of using an ROV to deploy seismometers in well- coupled configurations that are also away from the effects of ocean currents. A preliminary analysis of the first year of Keck seismic data was undertaken during a research apprenticeship class taught in the fall of 2004 at the University of Washington's Friday Harbor Laboratories. Eight post- baccalaureate students obtained a preliminary catalog of nearly 13,000 earthquakes on the Endeavour segment. Two of the apprentices conducted a second-pass analysis to refine the locations of ~3000 earthquakes that are within or near the network. Further analysis of these proximal earthquakes has focused on the application of cross-correlation and relative relocation techniques, the determination of focal mechanisms using P-wave first motions and P- to S-wave amplitudes ratios, and improved estimates of earthquake magnitudes. The results show that the entire Endeavour segment was seismically active during 2003-2004. Within the network, the earthquakes are located in tight clusters centered at ~2 km depth in the inferred location of the hydrothermal reaction zone immediately above a crustal magma chamber imaged by seismic reflection studies. The number of earthquakes below each hydrothermal vent field correlates with the heat flux measured by other researchers and the vertical thickness of this reaction zone, inferred from the distribution of seismicity, is ~0.5-1 km. Preliminary focal mechanisms show a transition from ridge-perpendicular extension beneath the rise axis to ridge-perpendicular compression on either side over horizontal distances of <1 km. This is most simply explained if the stress field above the magma chamber is locally influenced by either the injection of magma or over-pressured hydrothermal fluids. This observation, in combination with a reaction zone thickness that is at least an order of magnitude larger than that inferred from thermal boundary layer theory, suggests that the heat transfer between the magmatic and hydrothermal systems is not simply the result of cold water attacking hot magma. Instead, it appears as though the magmatic system also attacks the reaction zone from below.

Wilcock, W. S.; Hooft, E. E.; McGill, P. R.; Toomey, D. R.; Barclay, A. H.; Stakes, D. S.; Ramirez, T. M.

2007-12-01

225

High-Resolution Micro-Bathymetry Mapping in the Lau Basin: Examples From the Tui Malila and Mariner Vent Sites  

NASA Astrophysics Data System (ADS)

High-resolution SM2000 (200 kHz) multibeam sonar data were collected at six vent areas on the Lau Basin spreading center in April 2005. Data were acquired during near-bottom surveys conducted with the ROV Jason II at altitudes ranging from 5 to 20 m. High altitude (20 m) bathymetric surveys were complemented by near-bottom visual surveys, which provided ground-truth observations of the seafloor. Combined with Doppler and Long Baseline (LBL) Navigation, these bathymetry data provide sub-meter resolution of seafloor features, and reveal individual vent structures, faults and fissures. We present bathymetry data from two sites located 22 km apart, which are geologically and biologically distinct and exhibit contrasts in venting styles and biota. The Mariner vent field contains massive vent structures, many of which are taller than 25 m, with active venting from their bases and sides. Fluids exit as vigorous, high-temperature (< 363°C) black smoker fluids through chalcopyrite-lined conduits, and as less focused flow from porous beehive structures. Inactive structures are friable and are composed of iron- and copper-oxides. There was little evidence of faulting or fracture at the vent field, but we note the presence of collapsed volcanic dome structures. The vent fauna at Mariner is very limited; only Bythograeid and Galatheid crabs, and one Brisingid Seastar, were found. Tui Malila, by contrast, is characterized by shorter and wider branched vent structures with coalesced spires, the tops of which were actively venting. There is extensive faulting and fracture at this site, as well as a number of large flanges and areas of diffuse flow. At Tui Malila fluids exit tall structures through chalcopyrite- and zinc-lined conduits (at temperatures < 312°C), from beneath flanges, and directly from andesite. Hydrothermal breccias are also present. Tui Malila hosts a more typical vent community, with greater abundances of both Bythograeid and Galatheid crabs, mostly within 4 m of the vent field. Ifremeria Nautilei and Bathymodiolus Brevior were prolific within 2 m of the vent field, and sponges and anemones abundant from 4 to 32 m away.

Ferrini, V.; Sterling, A.; Martinez, F.; Tivey, M. K.; Mottl, M.; Kim, S.

2005-12-01

226

Life and death of deep-sea vents: bacterial diversity and ecosystem succession on inactive hydrothermal sulfides.  

PubMed

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

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

2012-01-24

227

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

PubMed Central

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.

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

2012-01-01

228

Geochemistry of hydrothermal fluids from Axial Seamount Hydrothermal Emissions Study vent field, Juan de Fuca Ridge: Subseafloor boiling and subsequent fluid-rock interaction  

Microsoft Academic Search

Hydrothermal fluids collected from the ASHES vent field in 1986, 1987, and 1988 exhibit a very wide range of chemical composition over a small area (â¼ 60 m in diameter). Compositions range from a 300C, gas-enriched (285 mmol\\/kg COâ), low-chlorinity (â¼ 33% of seawater) fluid to a 328C, relatively gas-depleted (50 mmol\\/kg COâ), high-chlorinity (â¼ 116% of seawater) fluid. The

David A. Butterfield; R. E. McDuff; M. D. Lilley; G. J. Massoth; J. E. Lupton

1990-01-01

229

Microbial Community of a Hydrothermal Mud Vent Underneath the Deep-Sea Anoxic Brine Lake Urania (Eastern Mediterranean)  

NASA Astrophysics Data System (ADS)

The composition of a metabolically active prokaryotic community thriving in hydrothermal mud fluids of the deep-sea hypersaline anoxic Western Urania Basin was characterized using rRNA-based phylogenetic analysis of a clone library. The physiologically active prokaryotic assemblage in this extreme environment showed a great genetic diversity. Most members of the microbial community appeared to be affiliated to yet uncultured organisms from similar ecosystems, i.e., deep-sea hypersaline basins and hydrothermal vents. The bacterial clone library was dominated by phylotypes affiliated with the epsilon- Proteobacteria subdivision recognized as an ecologically significant group of bacteria inhabiting deep-sea hydrothermal environments. Almost 18% of all bacterial clones were related to delta- Proteobacteria, suggesting that sulfate reduction is one of the dominant metabolic processes occurring in warm mud fluids. The remaining bacterial phylotypes were related to alpha- and beta- Proteobacteria, Actinobacteria, Bacteroides, Deinococcus-Thermus, KB1 and OP-11 candidate divisions. Moreover, a novel monophyletic clade, deeply branched with unaffiliated 16S rDNA clones was also retrieved from deep-sea sediments and halocline of Urania Basin. Archaeal diversity was much lower and detected phylotypes included organisms affiliated exclusively with the Euryarchaeota. More than 96% of the archaeal clones belonged to the MSBL-1 candidate order recently found in hypersaline anoxic environments, such as endoevaporitic microbial mats, Mediterranean deep-sea mud volcanoes and anoxic basins. Two phylotypes, represented by single clones were related to uncultured groups DHVE-1 and ANME-1. Thus, the hydrothermal mud of hypersaline Urania Basin seems to contain new microbial diversity. The prokaryotic community was significantly different from that occurring in the upper layers of the Urania Basin since 60% of all bacterial and 40% of all archaeal phylotypes were obtained only from mud fluids. The uniqueness of the composition of the active prokaryotic community could be explained by the complex environmental conditions at the site. The interaction of oxygenated warm mud fluids with the cold hypersaline brine of the Urania Basin seems to simultaneously select for various metabolic processes, such as aerobic and anaerobic heterotrophy, sulfide- and methane-dependent chemotrophy along with anaerobic oxidation of methane, sulfate- and metal-reduction.

Yakimov, Michail M.; Giuliano, Laura; Cappello, Simone; Denaro, Renata; Golyshin, Peter N.

2007-04-01

230

Microbial Diversity of Hydrothermal Vent Neutrally-Buoyant Plume Particles From 9 North, East Pacific Rise, After a Major Tectonic Event in 2005-2006  

NASA Astrophysics Data System (ADS)

Bacterial communities associated with descending, non-buoyant plume particles were collected in two sediment traps at 9°N on the East Pacific Rise over a 126 day period after a major tectonic event at the mid-oceanic ridge in 2005-2006. The communities from 15 trap samples were compared using Automated Ribosomal Intergenic Spacer Analysis (ARISA) analyzed using Bray-Curtis similarity on Primer6 software. Mean average values for OTUs of the samples and their replicates reveal spatial variation between sampling sites to be less significant than temporal variation: samples from both sites showed at least 50 - 60% similarity to each other, but temporal results suggest a distinctly different microbial community arising at the latest sampling times (i.e. 120-126 days). To draw more absolute measurements of spatial and temporal variation in the microbial communities within plume particles, samples from both vent sites and time regimes were selected for targeted sequencing of the 16S rRNA gene based on the ARISA results. Results from these sequencing efforts will be discussed and put in context with other diversity data from the geochemical endpoints of vent plumes: bottom water ambient seawater and hydrothermal fluids. In the future, we will use 454/V6-TAG sequencing to complement ARISA fingerprints and targeted sequencing and to assess total community diversity. These data will be analyzed in concert with geochemical and mineralogical data to reveal trends in biogeochemical processes in hydrothermal plumes and their correlation to microbial communities.

Pyenson, B. C.; Sylvan, J. B.; Toner, B. M.; Rouxel, O. J.; German, C. R.; Edwards, K. J.

2008-12-01

231

Towards a Genome-Enabled Sensor for In Situ Monitoring of Microbial Communities in Hydrothermal Vent Fields  

NASA Astrophysics Data System (ADS)

We report the progress towards a genome-enabled instrument to monitor variations in microbial community in hydrothermal vent fields for long durations. Our long-term goal is to deploy an in situ microarray device embedded in a lab-on-a-chip device. The microarray detects both the 16S rRNA to identify prokaryotic species and cDNA (converted from mRNA) of selected functional genes to understand activities and dynamics of ocean microbial communities. Each automated, self-contained instrument contains a stack of disposable lab-on-a-chip devices. All measurements are performed on individual chips, starting with pumping seawater through on-chip filter to collect microbes, lysing cells to release nucleic acids, and then analyzing their genomic information. To aid the effort of building the first functional microarray, we participated in the TN-221 cruise funded by the National Science Foundation's Ocean Observatories Initiative to map the seafloor in areas of high scientific interest. During the cruise, multiple deep-sea water samples were collected. The microbes were filtered, frozen and shipped to our laboratory for molecular analysis. The DNA was isolated from these samples and a detailed metagenomic analysis is ongoing for samples of one site (80 km offshore of Oregon coast, 380 km away from the Axial Seamount vent field, and 5 meters above the 780- meter deep seafloor). From the isolated chromosomal DNA the 16S rRNA clone library was constructed and resultant clones were sequenced. Although the fluorescence microscopic analyses showed the density of biomass is relatively low, phylogenetic results suggested high diversity in these microbial communities. In addition, efforts were made to isolate mRNA directly from these deep-sea ocean samples. The information obtained from these analyses will be essential for development of oligonucleotide probes for the microarray device. First two authors contributed equally.

Shi, X.; Wu, J.; Gao, W.; Chao, S.; Zhang, W.; Meldrum, D. R.

2008-12-01

232

Dominance of Epiphytic Filamentous Thiothrix spp. on an Aquatic Macrophyte in a Hydrothermal Vent Flume in Sedge Bay, Yellowstone Lake, Wyoming  

Microsoft Academic Search

Sublacustrine hydrothermal vents, geysers, and fumaroles impart regions of Yellowstone Lake with distinctive chemical compositions\\u000a that generate unique freshwater habitats and support diverse microbial life. Some microbial communities within Sedge Bay manifest\\u000a themselves as accumulations of white-colored films on the surfaces of aquatic macrophytes located within the hydrothermal\\u000a flow of vents. It was hypothesized that the white films were the

Nick R. Konkol; James C. Bruckner; Carmen Aguilar; David Lovalvo; James S. Maki

2010-01-01

233

Effects of sulfide exposure history and hemolymph thiosulfate on oxygen-consumption rates and regulation in the hydrothermal vent crab Bythograea thermydron  

Microsoft Academic Search

The hydrothermal vent crab Bythograea thermydron is exposed to high environmental concentrations of sulfide and low levels of oxygen for extended periods of time. It has previously been shown that hydrogen sulfide is oxidized to the relatively non-toxic thiosulfate (S2O32-), which accumulates in the hemolymph. Hemolymph thiosulfate levels in freshly captured crabs vary significantly among crabs from different hydrothermal vent

L. A. Gorodezky; J. J. Childress

1994-01-01

234

Prokaryote Diversity and Virus Abundance in Shallow Hydrothermal Vents of the Mediterranean Sea (Panarea Island) and the Pacific Ocean (North Sulawesi-Indonesia)  

Microsoft Academic Search

Despite their ubiquitous distribution in tectonically active coastal zones, shallow water hydrothermal vents have been less\\u000a investigated than deep-sea vents. In the present study, we investigated the role of viral control and fluid emissions on prokaryote\\u000a abundance, diversity, and community structure (total Archaea, total Bacteria, and sulphate-reducing bacteria) in waters and\\u000a sediments surrounding the caldera of four different shallow-water hydrothermal

E. Manini; G. M. Luna; C. Corinaldesi; D. Zeppilli; G. Bortoluzzi; G. Caramanna; F. Raffa; R. Danovaro

2008-01-01

235

Carbon-Isotope Fractionations of Autotrophic Bacteria: Relevance to Primary Production and Microbial Evolution in Hot Springs and Hydrothermal Vents  

NASA Astrophysics Data System (ADS)

Terrestrial hot springs and marine hydrothermal vents are often dominated by autotrophic microorganisms. Species of the Bacteria Domain in these environments are known to use different pathways for CO2 fixation. These may include the Calvin cycle, the Acetyl CoA pathway, the reverse TCA cycle, and the 3-HP pathway. Each cycle or pathway may be characterized by distinct patterns of carbon isotope fractionation. This presentation will summarize isotope fractionation patterns associated with known autotrophic bacteria and to use these patterns for interpreting natural isotopic variations. Examples will include hot springs from the Yellowstone National Park and Nevada desert, USA and Kamchatka, Russia, and hydrothermal vents from the East Pacific Rise. An attempt will be made to discuss isotopic variations within a particular pathway in the context of species evolution through horizontal gene transfer.

Zhang, C. L.; Romanek, C. S.; Mills, G.

2004-12-01

236

210Po and 210Pb disequilibrium in the hydrothermal vent fluids and chimney deposits from Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

Significantly deficient 210Po/210Pb activity ratios (0.14±0.14) are measured in the hydrothermal vent fluids collected from Juan de Fuca Ridge. Chimney deposits generally showed <5 dpm of excess 210Po. However, one sample from the outermost layer of a sealed spire yielded >1200 dpm g-1 of excess 210Po.If the observed 210Po-210Pb disequilibrium in vent fluids is a result of 210Po removal by the precipitates, residence time of polonium with respect to its irreversible removal from hot fluids is estimated to be of the order of a few minutes. Alternatively, if the disequilibrium is a result of an insufficient growth of 210Po from in-situ 210Pb following heating, the residence time of hot fluids within the hydrothermal system can be shown to be less than 30 days, which is considerably lower than previously reported values.

Hussain, N.; Church, T. M.; Luther, G. W., III; Moore, W. S.

237

Pathways of Carbon and Energy Metabolism of the Epibiotic Community Associated with the Deep-Sea Hydrothermal Vent Shrimp Rimicaris exoculata  

PubMed Central

Background The shrimp Rimicaris exoculata dominates the faunal biomass at many deep-sea hydrothermal vent sites at the Mid-Atlantic Ridge. In its enlarged gill chamber it harbors a specialized epibiotic bacterial community for which a nutritional role has been proposed. Methodology/Principal Findings We analyzed specimens from the Snake Pit hydrothermal vent field on the Mid-Atlantic Ridge by complementing a 16S rRNA gene survey with the analysis of genes involved in carbon, sulfur and hydrogen metabolism. In addition to Epsilon- and Gammaproteobacteria, the epibiotic community unexpectedly also consists of Deltaproteobacteria of a single phylotype, closely related to the genus Desulfocapsa. The association of these phylogenetic groups with the shrimp was confirmed by fluorescence in situ hybridization. Based on functional gene analyses, we hypothesize that the Gamma- and Epsilonproteobacteria are capable of autotrophic growth by oxidizing reduced sulfur compounds, and that the Deltaproteobacteria are also involved in sulfur metabolism. In addition, the detection of proteobacterial hydrogenases indicates the potential for hydrogen oxidation in these communities. Interestingly, the frequency of these phylotypes in 16S rRNA gene clone libraries from the mouthparts differ from that of the inner lining of the gill chamber, indicating potential functional compartmentalization. Conclusions Our data show the specific association of autotrophic bacteria with Rimicaris exoculata from the Snake Pit hydrothermal vent field, and suggest that autotrophic carbon fixation is contributing to the productivity of the epibiotic community with the reductive tricarboxylic acid cycle as one important carbon fixation pathway. This has not been considered in previous studies of carbon fixation and stable carbon isotope composition of the shrimp and its epibionts. Furthermore, the co-occurrence of sulfur-oxidizing and sulfur-reducing epibionts raises the possibility that both may be involved in the syntrophic exchange of sulfur compounds, which could increase the overall efficiency of this epibiotic community.

Hugler, Michael; Petersen, Jillian M.; Dubilier, Nicole; Imhoff, Johannes F.; Sievert, Stefan M.

2011-01-01

238

Molecular identification of differentially regulated genes in the hydrothermal-vent species Bathymodiolus thermophilus and Paralvinella pandorae in response to temperature  

Microsoft Academic Search

BACKGROUND: Hydrothermal vents and cold seeps represent oases of life in the deep-sea environment, but are also characterized by challenging physical and chemical conditions. The effect of temperature fluctuations on vent organisms in their habitat has not been well explored, in particular at a molecular level, most gene expression studies being conducted on coastal marine species. In order to better

Isabelle Boutet; Didier Jollivet; Bruce Shillito; Dario Moraga; Arnaud Tanguy

2009-01-01

239

Submarine hydrothermal activity along the mid-Kermadec Arc, New Zealand: Large-scale effects on venting  

Microsoft Academic Search

The 2,500-km Kermadec-Tonga arc is the longest submarine arc on the planet. Here, we report on the second of a series of cruises designed to investigate large-scale controls on active hydrothermal venting on this arc. The 2002 NZAPLUME II cruise surveyed 12 submarine volcanic centers along ?580 km of the middle Kermadec arc (MKA), extending a 1999 cruise that surveyed

C. E. J. de Ronde; E. T. Baker; G. J. Massoth; J. E. Lupton; I. C. Wright; R. J. Sparks; S. C. Bannister; M. E. Reyners; S. L. Walker; R. R. Greene; J. Ishibashi; K. Faure; J. A. Resing; G. T. Lebon

2007-01-01

240

ϵ-Proteobacterial diversity from a deep-sea hydrothermal vent on the Mid-Atlantic Ridge  

Microsoft Academic Search

The prokaryotic phylogenetic diversity was determined for a sample associated with an in situ growth chamber deployed for 5 days on a Mid-Atlantic Ridge hydrothermal vent (23‡22PN, 44‡57PW). The DNA was extracted from the sample and the 16S rDNA amplified by PCR. No Archaea were detected in the sample. Eighty-seven clones containing bacterial 16S rDNA inserts were selected. Based on

Erwan Corre; Anna-Louise Reysenbach; Daniel Prieur

2001-01-01

241

Diversity of Dissimilatory Bisulfite Reductase Genes of Bacteria Associated with the Deep-Sea Hydrothermal Vent Polychaete Annelid Alvinella pompejana  

Microsoft Academic Search

A unique community of bacteria colonizes the dorsal integument of the polychaete annelid Alvinella pompe- jana, which inhabits the high-temperature environments of active deep-sea hydrothermal vents along the East Pacific Rise. The composition of this bacterial community was characterized in previous studies by using a 16S rRNA gene clone library and in situ hybridization with oligonucleotide probes. In the present

MATTHEW T. COTTRELL; S. CRAIG CARY

1999-01-01

242

The zinc-mediated sulfide-binding mechanism of hydrothermal vent tubeworm 400-kDa hemoglobin  

Microsoft Academic Search

Hydrothermal vent and cold seep tubeworms possess two hemoglobin (Hb) types, a 3600-kDa hexagonal bilayer Hb as well as a 400-kDa spherical Hb. Both Hbs can reversibly and simultaneously bind and transport oxygen and hydrogen sulfide used by the worm's endosymbiotic bacteria to fix carbon. The vestimentiferan 400-kDa Hb has been shown to consist of 24 polypeptide chains and 12

Jason F. FLORES; Stéphane M. HOURDEZ

243

Compositional, Physiological and Metabolic Variability in Microbial Communities Associated with Geochemically Diverse, Deep-Sea Hydrothermal Vent Fluids  

Microsoft Academic Search

\\u000a Deep-sea hydrothermal vent environments represent one of the most physically and chemically diverse biomes in Earth. The chemical\\u000a and thermal gradients (e.g., >350°C across distances as small as several centimeters in active chimneys) provide a wide range\\u000a of niches for microbial communities living there (Huber and Holden 2008; Nakagawa and Takai 2008; Reysenbach et al. 2000;\\u000a Takai et al. 2006a).

Ken Takai; Kentaro Nakamura

244

Towards a Genome-Enabled Sensor for In Situ Monitoring of Microbial Communities in Hydrothermal Vent Fields  

Microsoft Academic Search

We report the progress towards a genome-enabled instrument to monitor variations in microbial community in hydrothermal vent fields for long durations. Our long-term goal is to deploy an in situ microarray device embedded in a lab-on-a-chip device. The microarray detects both the 16S rRNA to identify prokaryotic species and cDNA (converted from mRNA) of selected functional genes to understand activities

X. Shi; J. Wu; W. Gao; S. Chao; W. Zhang; D. R. Meldrum

2008-01-01

245

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

Microsoft Academic Search

Deep-sea vestimentiferan tubeworms, which live in symbiosis with bacteria, exhibit different life strategies according to\\u000a their habitat. At unstable and relatively short-lived hydrothermal vents, they grow extremely fast, whereas their close relatives\\u000a at stable and long-persisting cold seeps grow slowly and live up to 300 years. Growth and age differences are thought to occur\\u000a because of ecological and physiological adaptations. However,

Bettina Pflugfelder; S. Craig Cary; Monika Bright

2009-01-01

246

Sulfide-Driven Autotrophic Balance in the Bacterial Symbiont-Containing Hydrothermal Vent Tubeworm, Riftia pachyptila Jones  

Microsoft Academic Search

Hydrothermal vent tubeworms, Riftia pa- chyptila Jones, were maintained alive and studied on board ship using flow-through pressure aquaria. Simul- taneous measurements of 02, ZC02, ZH2S fluxes showed that the intact symbioses reach maximum rates of uptake of xC02 (>2 pmole g-' h-') at about 90 pA4 Z1H2S. Mea- surements were made of hemolymph and coelomic fluid I;C02, ZH2S, thiosulfate,

J. J. CHILDRESS; C. R. FISHER; J. A. FAVUZZI; R. E. KOCHEVAR; N. K. SANDERS; A. M. ALAYSE

1991-01-01

247

Novel Bacterial and Archaeal Lineages from an In Situ Growth Chamber Deployed at a Mid-Atlantic Ridge Hydrothermal Vent  

Microsoft Academic Search

The phylogenetic diversity was determined for a microbial community obtained from an in situ growth chamber placed on a deep-sea hydrothermal vent on the Mid-Atlantic Ridge (23°22* N, 44°57* W). The chamber was deployed for 5 days, and the temperature within the chamber gradually decreased from 70 to 20°C. Upon retrieval of the chamber, the DNA was extracted and the

ANNA-LOUISE REYSENBACH; KRISTA LONGNECKER; JULIE KIRSHTEIN

2000-01-01

248

Stable carbon and nitrogen isotopic signatures of fauna associated with the deep-sea hydrothermal vent system of Guaymas Basin, Gulf of California  

Microsoft Academic Search

Potential food sources and the trophic position of some of the most conspicuous faunal components (vent and non-vent) were examined in the deep-hydrothermal vent system of Guaymas Basin, in the Gulf of California using carbon and nitrogen stable isotope analyses. The isotopic signatures of 13 species collected by the DSRV Alvin and Nautile mostly from sulfide-influenced habitats were analyzed. The

Luis A. Soto

2009-01-01

249

POM in macro-\\/meiofaunal food webs associated with three flow regimes at deep-sea hydrothermal vents on Axial Volcano, Juan de Fuca Ridge  

Microsoft Academic Search

Deep-sea hydrothermal vent ecosystems host both symbiotic and non-symbiotic invertebrates. The non-symbiotic vent fauna is\\u000a generally assumed to rely on free-living chemoautotrophic bacteria as their main food source but other sources such as detritus\\u000a have recently been suggested to be a part of the invertebrate diets. Little is known about how food availability influences\\u000a the distribution of vent organisms on

Helene Limén; Christian Levesque; S. Kim Juniper

2007-01-01

250

Gas venting rates from submarine hydrothermal areas around the island of Milos, Hellenic Volcanic Arc  

Microsoft Academic Search

Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at hydrothermal sites around the island of Milos, in the Hellenic Volcanic Arc. Samples were collected by SCUBA divers and by a ROV from water depths between 3 and 110 m. Fifty-six flow rates from 39 individual seeps were measured and these ranged from 0.2 to 18.51 h?1

P. R. Dando; J. A. Hughes; Y. Leahy; S. J. Niven; L. J. Taylor; C. Smith

1995-01-01

251

Physical controls on the salinity of mid-ocean ridge hydrothermal vent fluids  

NASA Astrophysics Data System (ADS)

Variations in the salinity of black smoker effluents (0.1-˜ 8 wt.% NaCl) relative to seawater (3.2 wt.% NaCl) are attributed to phase separation and segregation of the resulting brines and vapors. However, models of phase separation predict brines with substantially higher salinities than observed at vents and such brines are commonly observed in fluid inclusions from fossil hydrothermal systems. It has been postulated that the range of observed salinities is controlled by the density of upwelling fluids. Here we present models of hydrothermal circulation that predict the observed maximum salinity when an upper layer of high-permeability is included, and also reproduce black smoker temperatures when the upflow zone is surrounded by a low-permeability shell. Pressure gradients across the permeability boundary act as a density filter impeding the passage of high-salinity fluids, while the shell provides sufficient insulation to tap hot fluids to the surface. Our models fit the observations when the permeabilities of the upper layer differ from the permeability of the lower layer by factors of ˜ 10 and ˜ 100 in upflow and downflow regions, respectively, and when the permeability of the shell is one tenth that of the lower layer. The permeability structure we propose is consistent with observations in oceanic crust and inferences from ophiolites. While a previous study argues that black smoker temperatures are a consequence of the thermodynamic properties of seawater, our work suggests that very specific permeability configurations are required to match both the temperature and maximum salinity.

Fontaine, Fabrice J.; Wilcock, William S. D.; Butterfield, David A.

2007-05-01

252

Nitrogen Reduction Under Hydrothermal Vent Conditions: Implications for the Prebiotic Synthesis of C-H-O-N Compounds  

NASA Astrophysics Data System (ADS)

Dinitrogen is reduced in dilute hydrogen sulfide (H2S) solutions to ammonium at 120°C. Experiments with dissolved dinitrogen (partial pressure 50 bar) in a 12 × 10-3 mol/L H2S(aq) solution yield ~10-5 mol/L NH4+ within 2-7 days. These yields are consistent with the equilibrium NH4+ concentration for the N-S-H system under these conditions. The formation of ammonium is catalyzed by the presence of freshly precipitated iron monosulfide. These results indicate that dinitrogen can be reduced at moderate temperatures in hydrothermal vent systems. Abiotic nitrogen reduction could have taken place within primordial hydrothermal vents, supplying some ammonia for the synthesis of C-H-O-N compounds via abiotic processes. The yield of ammonia via dinitrogen reduction by hydrogen sulfide, however, is so low that it is doubtful this process could have produced enough ammonia to sustain prebiotic hydrothermal synthesis of C-H-O-N compounds in or around vent systems.

Schoonen, Martin A. A.; Xu, Yong

2001-06-01

253

Tidal bottom current modulation of chemical environment in the Suiyo hydrothermal site in the Izu-Ogasawara (Bonin) Arc.  

NASA Astrophysics Data System (ADS)

Intense seafloor observatory studies were done at the Suiyo hydrothermal site in the summer of 2001 and 2002. Deployed instruments on the seafloor were CTD (Idronaut, Ocean Seven 316), Digiquartz precision pressure sensor and its recorder, 3-D acoustic current meters (NOBSKA, MAVS3), high temperature and redox recorders at the vents, in-situ laser particle analyzer (Sequoia Scientific, LISST-Deep), methane sensor (CAPSUM METS) with its data logger, etc. The Suiyo Seamount hydrothermal site is located in the summit caldera of Izu-Ogasawara (Bonin) Arc (1380 m deep, 28.572 N, 140.643 E). The tide is mixed type dominant with semi-diurnal component. There is no tidal components in temperature and redox records neither at high temperature vents (300 deg C) nor at low temperature vents (less than 200 deg C). Whereas the temperature, redox, methane concentration in the seawater, particle characters measured just above the seafloor had strong semi-diurnal components. The methane concentration varies from several micro mol/litter to several tens of micro mol/litter associated with 200 mV redox change in the central part of the hydrothermal site. Semi-diurnal strong bottom current over 40 cm/sec appeared several hours after high tides introduced entrainment of ambient waters in the marginal part of hydrothermal site and accelerated mixing of vent water with bottom water in the central part of the hydrothermal site. This research was funded by the "Archaean Park" Project (International research project on interaction between sub-vent biosphere and geo environment funded by Special Coordination Fund of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The R/V Natsushima cruise with the sub "Shinkai 2000" was a part of the Deep Sea Research project of the Japan Marine Science and Technology Center (JAMSTEC).

Nakamura, K.

2002-12-01

254

Migration, isolation, and speciation of hydrothermal vent limpets (Gastropoda; Lepetodrilidae) across the Blanco Transform Fault.  

PubMed

The Sovanco Fracture Zone and Blanco Transform Fault separate the Explorer, Juan de Fuca, and Gorda ridge systems of the northeastern Pacific Ocean. To test whether such offsets in the ridge axis create barriers to along-axis dispersal of the endemic hydrothermal vent animals, we examined the genetic structure of limpet populations previously identified as Lepetodrilus fucensis McLean, 1988 (Gastropoda, Lepetodrilidae). Mitochondrial DNA sequences and patterns of allozyme variation revealed no evidence that the 150-km-long Sovanco Fracture Zone impeded gene flow between the Explorer and Juan de Fuca populations. In contrast, the 450-km-long Blanco Transform Fault separates the limpets into highly divergent northern and southern lineages that we recognize as distinct species. We describe southern populations from the Gorda Ridge (Seacliff) and Escanaba Trough as Lepetodrilus gordensis new species and refer northern populations from the Explorer and Juan de Fuca ridge systems to L. fucensis sensu stricto. The species are similar morphologically, but L. gordensis lacks a sensory neck papilla and has a more tightly coiled teleconch. To assess the degree of isolation between these closely related species, we used the Isolation with Migration method to estimate the time of population splitting, effective sizes of the ancestral and derived populations, and rates of migration across the Blanco Transform Fault. PMID:16641519

Johnson, Shannon B; Young, Curtis R; Jones, William J; Warén, Anders; Vrijenhoek, Robert C

2006-04-01

255

Identity and mechanisms of alkane-oxidizing metalloenzymes from deep-sea hydrothermal vents.  

PubMed

Six aerobic alkanotrophs (organism that can metabolize alkanes as their sole carbon source) isolated from deep-sea hydrothermal vents were characterized using the radical clock substrate norcarane to determine the metalloenzyme and reaction mechanism used to oxidize alkanes. The organisms studied were Alcanivorax sp. strains EPR7 and MAR14, Marinobacter sp. strain EPR21, Nocardioides sp. strains EPR26w, EPR28w, and Parvibaculum hydrocarbonoclasticum strain EPR92. Each organism was able to grow on n-alkanes as the sole carbon source and therefore must express genes encoding an alkane-oxidizing enzyme. Results from the oxidation of the radical-clock diagnostic substrate norcarane demonstrated that five of the six organisms (EPR7, MAR14, EPR21, EPR26w, and EPR28w) used an alkane hydroxylase functionally similar to AlkB to catalyze the oxidation of medium-chain alkanes, while the sixth organism (EPR92) used an alkane-oxidizing cytochrome P450 (CYP)-like protein to catalyze the oxidation. DNA sequencing indicated that EPR7 and EPR21 possess genes encoding AlkB proteins, while sequencing results from EPR92 confirmed the presence of a gene encoding CYP-like alkane hydroxylase, consistent with the results from the norcarane experiments. PMID:23825470

Bertrand, Erin M; Keddis, Ramaydalis; Groves, John T; Vetriani, Costantino; Austin, Rachel Narehood

2013-05-10

256

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

PubMed

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 Fe(3+)-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe(2+)-oxidation, dependent on microbially produced nitrate. PMID:23939372

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

2013-08-13

257

Microdistribution pattern and biogeography of the hydrothermal vent communities of the Minami-Ensei Knoll in the mid-Okinawa trough, Western Pacific  

NASA Astrophysics Data System (ADS)

From 1988 to 1992, a series of deep-sea surveys was conducted to characterize hydrothermal vent fields on the Minami-Ensei Knoll, approximately 140 km west of Amami-Ohshima Island, southwest Japan, with a multi-narrow beam mapping system (Sea Beam), deep tow observing systems and the submersible Shinkai 2000. The vent fields were centered around the depressions on the western slope of the knoll. The hydrothermal vents emitted superheated water over 269°C through chimneys. Diffuse fluid discharged from fissures in rocks. Numerous patches of grayish white hydrothermal stains were observed on the bottom of coarse sand. Vent-associated biological communities consisted of sponges, vestimentiferans, alvinellid and polynoid polychaetes, cerithiid and trochid gastropods, lepetrodrillid limpets, vesicomyid clams, mytilid bivalves, bresiliid and hippolytid shrimp, zoarcid and cynoglossid fish, and lithodid and galatheid crabs. The hydrothermal vent communities of the Minami-Ensei Knoll showed many similarities to those of the Kaikata Seamount, the Mariana Back-Arc Spreading Center, the North Fiji Basin and the Lau Basin, as well as the cold seep communities of Sagami Bay. There may be considerable interchange among the Minami-Ensei knoll communities and other chemosynthetic communities in the Western Pacific despite the 1000 km distance separating these communities and the existence of Ryukyu Trench and Ryukyu Arc. These discoveries, as well as other more recent findings around Japan, contribute significantly to our understanding of the biogeography of the hydrothermal vent and cold seep communities in the Western Pacific.

Hashimoto, Jun; Ohta, Suguru; Fujikura, Katsunori; Miura, Tomoyuki

1995-04-01

258

Abundance of Reverse Tricarboxylic Acid Cycle Genes in Free-Living Microorganisms at Deep-Sea Hydrothermal Vents  

PubMed Central

Since the discovery of hydrothermal vents more than 25 years ago, the Calvin-Bassham-Benson (Calvin) cycle has been considered the principal carbon fixation pathway in this microbe-based ecosystem. However, on the basis of recent molecular data of cultured free-living and noncultured episymbiotic members of the epsilon subdivision of Proteobacteria and earlier carbon isotope data of primary consumers, an alternative autotrophic pathway may predominate. Here, genetic and culture-based approaches demonstrated the abundance of reverse tricarboxylic acid cycle genes compared to the abundance of Calvin cycle genes in microbial communities from two geographically distinct deep-sea hydrothermal vents. PCR with degenerate primers for three key genes in the reverse tricarboxylic acid cycle and form I and form II of ribulose 1,5-bisphosphate carboxylase/oxygenase (Calvin cycle marker gene) were utilized to demonstrate the abundance of the reverse tricarboxylic acid cycle genes in diverse vent samples. These genes were also expressed in at least one chimney sample. Diversity, similarity matrix, and phylogenetic analyses of cloned samples and amplified gene products from autotrophic enrichment cultures suggest that the majority of autotrophs that utilize the reverse tricarboxylic acid cycle are members of the epsilon subdivision of Proteobacteria. These results parallel the results of previously published molecular surveys of 16S rRNA genes, demonstrating the dominance of members of the epsilon subdivision of Proteobacteria in free-living hydrothermal vent communities. Members of the epsilon subdivision of Proteobacteria are also ubiquitous in many other microaerophilic to anaerobic sulfidic environments, such as the deep subsurface. Therefore, the reverse tricarboxylic acid cycle may be a major autotrophic pathway in these environments and significantly contribute to global autotrophic processes.

Campbell, Barbara J.; Cary, S. Craig

2004-01-01

259

Hydrothermal fluids vented at shallow depths at the Aeolian islands: relationships with volcanic and geothermal systems.  

NASA Astrophysics Data System (ADS)

Scuba diving investigations carried out over the last two decades at the Aeolian islands revealed the existence of submarine magmatic and late-magmatic hydrothermalism at all the islands, despite the absence of on-shore activity at some of the islands. The results gained by diving activities provided useful information to evaluate the volcanic and geothermal activity and to manage the volcanic crisis occurred on November 2002 off the island of Panarea. Scuba diving investigations carried out from middle 80's, had shown that despite the absence of on shore volcanic manifestations, submarine hydrothermal activity is recognizable at shallow depth around all the Aeolian islands related either to volcanic and geothermal activity. The sampled gases are CO2-dominated with low amounts of oxygen and reactive gases (H2, CO, CH4 and H2S) with concentrations ranging from a few ppm to some mole percent. Sometimes significant N2 amount are detectable together with high helium contents. Samples having low CO2 content, besides relevant N2 and He amounts, are the consequence of CO2 dissolution in sea-water due to gas-water interactions (GWI) occurred before the sample collection. The high CO2 solubility (878 ml/l, T=20°C, P=1bar) may, in fact, decrease the CO2 content in the venting gases thus increasing the concentrations of the less soluble species (e.g. He 8 ml/l, CO 23 ml/l and CH4 33.8 ml/l) in the gas mixture. Such a process might occur at any level, however, because of the slow water circulation in deep sediments, CO2 is able to saturate the circulating sea-water. The isotopic composition of carbon displays a small range of values while helium isotopes are in the range of 4.1venting gases from active volcanoes (e.g. Vulcano and Panarea). The explanation of such a difference is not related to the volcanic activity at all, but to the parent mantle that in the western side looks to be less contaminated compared to the eastern side. Crustal contamination has been invoked by several authors as the main factor that caused the dramatic 3He/4He decrease. Although the parent mantle produced magmas with different isotopic signature, the gas phase looks similar. To explain the results of the chemical analyses it is proposed that similar deep boundary conditions (pressure, temperature, oxidation level) act as buffers for the chemical composition of the venting gases. With the aim of investigating their origin, estimations of the deep equilibration conditions have been carried out. The reactive compounds detected in the sampled gases, largely used for geothermometric and geobarometric considerations of hydrothermal fluids were used in a system based on the CH4-CO-CO2 contents assuming the presence of a boiling aqueous solution. The equilibrium constants of the adopted reactions are a function of temperature and oxygen fugacity, being the latter buffered by the mineral assemblage of the host rocks. Due to the similarity in the chemical composition of the gases vented at all the islands, a theoretical model developed to interpret the chemical composition of the gases released at Panarea during the last volcanic crisis is here applied. The results have shown that geothermal boiling systems are detectable at all the islands with temperatures up to 350°C. The adopted geo-thermobarometric system is more sensitive to the contents of CO and CH4 than that of CO2, implying that although GWI induce modifications in the chemical composition, the estimated equilibrium temperatures do not change very much for variations of the CO2 content in the range of several volume percent, thus, whether or not the gaseous mixture underwent GWI. Moreover, the slow reaction kinetics of CO and CH4 allow them to keep the deep equilibrium c

Italiano, Francesco; Caracausi, Antonio; Longo, Manfredi; Maugeri, Roberto; Paonita, Antonio

2010-05-01

260

Fluid flow and mass flux determinations at vent sites on the Cascadia margin accretionary prism  

Microsoft Academic Search

Fluid venting from the toe of the accretionary prism off Oregon was measured in situ during a series of dives with DSRV Alvin in 1987 and 1988. A benthic chamber was placed over active vent sites to sequentially collect samples of venting fluids and to make direct measurements of discharge rates. Calibrated flow meter measurements and flow rates determined from

Bobb Carson; Erwin Suess; Jeffrey C. Strasser

1990-01-01

261

Novel Bacterial and Archaeal Lineages from an In Situ Growth Chamber Deployed at a Mid-Atlantic Ridge Hydrothermal Vent  

PubMed Central

The phylogenetic diversity was determined for a microbial community obtained from an in situ growth chamber placed on a deep-sea hydrothermal vent on the Mid-Atlantic Ridge (23°22? N, 44°57? W). The chamber was deployed for 5 days, and the temperature within the chamber gradually decreased from 70 to 20°C. Upon retrieval of the chamber, the DNA was extracted and the small-subunit rRNA genes (16S rDNA) were amplified by PCR using primers specific for the Archaea or Bacteria domain and cloned. Unique rDNA sequences were identified by restriction fragment length polymorphisms, and 38 different archaeal and bacterial phylotypes were identified from the 85 clones screened. The majority of the archaeal sequences were affiliated with the Thermococcales (71%) and Archaeoglobales (22%) orders. A sequence belonging to the Thermoplasmales confirms that thermoacidophiles may have escaped enrichment culturing attempts of deep-sea hydrothermal vent samples. Additional sequences that represented deeply rooted lineages in the low-temperature eurarchaeal (marine group II) and crenarchaeal clades were obtained. The majority of the bacterial sequences obtained were restricted to the Aquificales (18%), the ? subclass of the Proteobacteria (?-Proteobacteria) (40%), and the genus Desulfurobacterium (25%). Most of the clones (28%) were confined to a monophyletic clade within the ?-Proteobacteria with no known close relatives. The prevalence of clones related to thermophilic microbes that use hydrogen as an electron donor and sulfur compounds (S0, SO4, thiosulfate) indicates the importance of hydrogen oxidation and sulfur metabolism at deep-sea hydrothermal vents. The presence of sequences that are related to sequences from hyperthermophiles, moderate thermophiles, and mesophiles suggests that the diversity obtained from this analysis may reflect the microbial succession that occurred in response to the shift in temperature and possible associated changes in the chemistry of the hydrothermal fluid.

Reysenbach, Anna-Louise; Longnecker, Krista; Kirshtein, Julie

2000-01-01

262

Imaging microbial metal metabolism in situ under conditions of the deep-sea hydrothermal vents  

NASA Astrophysics Data System (ADS)

High-pressure biotopes are the most widely spread biotopes on Earth. They represent one possible location for the origin of life. They also share striking similarities with extraterrestrial biotopes such as those postulated for Europe or Mars. In absence of light, dissimilatory reduction of metals (DMR) is fueling the ecosystem. Monitoring the metabolism of the deep-sea hydrothermal vent microbial fauna under P, T and chemical conditions relevant to their isolation environment can be difficult because of the confinement and because most spectroscopic probes do not sense metallic ions in solution. We demonstrated the possibility to use Xray spectroscopy to monitor the speciation of metallic species in solution. Experiments were performed at The ESRF using Selenium (Se) detoxification by Agrobacterium tumefaciens as an analog of DMR. The reduction of Se from selenite to the metal was monitored by a combiantion of two Xray spectroscopic techniques (XANES and ?XRF). Cells were incubated in the low pressure DAC in growth medium supplemented with 5mM Selenite and incubated under pressures up to 60 Mpa at 30°C for 24h. The evolution of the speciation can be easily monitored and the concentration of each Se species determined from the Xray spectra by linear combinations of standard spectra. Selenite is transformed by the bacterium into a mixture of metal Se and methylated Se after 24 hours. Se detoxification is observed in situ up to at least 25 MPa. The technique, developped for Se can be adapted to monitor other elements more relevant to DMR such as As, Fe or S, which should allow to monitor in situ under controlled pressure and temperature the metabolism of vent organisms. It is also amenable to the monitoring of toxic metals. Xray spectroscopy and the lpDAC are compatible with other spectroscopic techniques, such as Raman, UV or IR spectroscopies, allowing to probe other metabolic activities. Hence, enlarging the range of metabolic information that can be obtained in situ. Oger PM, I Daniel, B Cournoyer, and A Simionovici (2004) Spectrochim Acta B 59:1681-1686 Oger PM, I Daniel, and A Picard (2006) BBA Prot Proteom 1764:434-442

Oger, P. M.; Daniel, I.; Simionovici, A.; Picard, A.

2006-12-01

263

A Mössbauer investigation of iron-rich terrestrial hydrothermal vent systems: Lessons for Mars exploration  

NASA Astrophysics Data System (ADS)

Hydrothermal spring systems may well have been present on early Mars and could have served as a habitat for primitive life. The integrated instrument suite of the Athena Rover has, as a component on the robotic arm, a Mössbauer spectrometer. In the context of future Mars exploration we present results of Mössbauer analysis of a suite of samples from an iron-rich thermal spring in the Chocolate Pots area of Yellowstone National Park (YNP) and from Obsidian Pool (YNP) and Manitou Springs, Colorado. We have found that Mössbauer spectroscopy can discriminate among the iron-bearing minerals in our samples. Those near the vent and on the surface are identified as ferrihydrite, an amorphous ferric mineraloid. Subsurface samples, collected from cores, which are likely to have undergone inorganic and/or biologically mediated alteration (diagenesis), exhibit spectral signatures that include nontronite (a smectite clay), hematite (?-Fe2O3), small-particle/nanophase goethite (?-FeOOH), and siderite (FeCO3). We find for iron minerals that Mössbauer spectroscopy is at least as efficient in identification as X-ray diffraction. This observation is important from an exploration standpoint. As a planetary surface instrument, Mössbauer spectroscopy can yield high-quality spectral data without sample preparation (backscatter mode). We have also used field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X ray (EDX) fluorescence spectroscopy, to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework. Evidence is presented that the minerals found in these deposits can have multibillion-year residence times and thus may have survived their possible production in a putative early Martian hot spring up to the present day. Examples include the nanophase property and the Mössbauer signature for siderite, which has been identified in a 2.09-billion-year old hematite-rich chert stromatolite. Our research demonstrates that in situ Mössbauer spectroscopy can help determine whether hydrothermal mineral deposits exist on Mars, which is significant for exobiology because of the issue of whether that world ever had conditions conducive to the origin of life. As a useful tool for selection of samples suitable for transport to Earth, Mössbauer spectroscopy will not only serve geological interests but will also have potential for exopaleontology.

Wade, Manson L.; Agresti, David G.; Wdowiak, Thomas J.; Armendarez, Lawrence P.; Farmer, Jack D.

1999-04-01

264

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

PubMed Central

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

Cary, S C; Giovannoni, S J

1993-01-01

265

Unusual carbon dioxide-combining properties of body fluids in the hydrothermal vent tubeworm Riftia pachyptila  

NASA Astrophysics Data System (ADS)

Total CO 2 (?CO 2) up to 50 mmol l -1, corresponding to internal CO 2 partial pressures (P CO 2) up to 6 kPa (1 kPa ? 7.5 mm Hg or Torr), have been measured in the body fluids of the hydrothermal vent tubeworm Riftia pachyptila (Jones) sampled at 13°N on the East Pacific Rise. At physiological pH values, such high ?CO 2 and P CO 2 are quite unusual in water-breathing animals. In Riftia, both blood and coelomic fluid contain extracellular haemoglobins at fairly high concentrations, but their titration by a strong acid as well as CO 2 equilibration experiments on dialysed and ultra-filtered fluids showed that the presence of these proteins account for only one-tenth to one-third of the observed ?CO 2. Gel filtration analysis of the fluids revealed that the protein-free fractions retained most of the CO 2: about 64% in blood and 80% in coelomic fluid. This corresponds to a base excess of unknowm nature and origin at a concentration up to 30 meq l -1. The nutritional needs of the mouthless and gutless Riftia are totally derived from the metabolic activity of sulphide-oxidizing, chemolithoautotrophic bacterial symbionts able to fix inorganic carbon into organic molecules. In an external environment in which P CO 2 varies widely due to the turbulent mixing of the hot, sulphide- and CO 2-rich vebt water with the cold, CO 2-poor deep sea water, we propose that the base excess has three main functions: first, to retain CO 2 in the body fluids when the external P CO 2 is low; second, to act as a buffer when external P CO 2 is high; third, to allow the large coelomic compartment to act as a CO 2 store, thus permitting the symbiotic bacteria to fix carbon continuously even when the external supply of carbon dioxide fluctuates.

Toulmond, André; Lallier, François H.; de Frescheville, Jacques; Childress, James J.; Lee, Raymond; Sanders, Nancy K.; Desbruyères, Daniel

1994-10-01

266

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)

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.

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

2013-10-01

267

Post-eruption succession of macrofaunal communities at diffuse flow hydrothermal vents on Axial Volcano, Juan de Fuca Ridge, Northeast Pacific  

NASA Astrophysics Data System (ADS)

Hydrothermal vents harbor dense aggregations of invertebrate fauna supported by chemosynthesis. Severe tectonic events and volcanic eruptions frequently destroy vent communities and initiate primary succession at new vents on ridge-crest submarine lava flows. An eruption on Axial Volcano (˜1500 m depth), a seamount on the Juan de Fuca Ridge (JdFR) in the northeast Pacific Ocean, occurred in January 1998, which created new substratum and vents. This study examines the development of the macrofaunal vent assemblages associated with tubeworms ( Ridgeia piscesae) at eight diffuse flow vents over the following 3 years. Biological collections by suction of lava surfaces also characterized "pre-tubeworm assemblages". Coupled fluid sampling showed an overall decrease in temperature, sulphide, and sulphide-to-heat ratios over 3 years as well as large spatial variability across the new vents. We examined collections of pre-eruption diffuse flow vent assemblages at Axial Volcano to compare the stages of new community development to "mature" vents. Mature vent assemblages are characterized by two major community types dominated by limpets ( Lepetodrilus fucensis) and alvinellid polychaetes ( Paralvinella pandorae and/or P. palmiformis). The following post-eruption succession patterns emerged. First, R. piscesae tubeworms took up to 3 years to establish aggregations at the new vents, and the majority of pre-tubeworm assemblages were dominated by grazing polychaetes. Second, species colonized quickly and by 30 months after habitat creation >60% of Axial's species pool had arrived at the new vents; abundance at mature vents predicted colonization success with some notable exceptions. Third, shifts in species dominance occurred rapidly and by Year 3 new vent assemblages resembled mature, pre-eruption communities. In general, tubeworm assemblages were dominated by alvinellid polychaetes ( P. pandorae and P. palmiformis) in the first 2 years post-eruption, with limpets ( L. fucensis) becoming more numerous in Year 3. Fourth, successional trajectories corresponded to four habitat variables: the timing of R. piscease recruitment, vent age, maximum vent fluid sulphide-to-heat ratios, and maximum vent fluid temperatures. The two mature community types (dominance by limpets or alvinellid polychaetes) seem to relate in part to vent differences in fluid properties, with limpets more prevalent than alvinellids at diffuse vents with lower maximum sulphide-to-heat ratios and temperatures. We present a general model of post-eruption succession for Juan de Fuca Ridge diffuse flow vents. The model incorporates potential abiotic and biotic drivers of community development and identifies six successional stages: a pre-tubeworm assemblage, four tubeworm assemblage states determined by the relative dominance of alvinellid polychaetes and the limpet, and a final senescent stage when venting wanes. Future eruptions will allow for this model to be tested through direct observation and experimentation.

Marcus, Jean; Tunnicliffe, Verena; Butterfield, David A.

2009-09-01

268

Visual Observations and Geologic Settings of the Newly-Discovered Black Smoker Vent Sites Across the Galapagos Ridge-Hotspot Intersection  

NASA Astrophysics Data System (ADS)

Nearly one-fifth of the global mid-ocean ridge is hotspot-affected, yet very little is known about how hotspots affect quantity and distribution of high-temperature hydrothermal vents along the ridge. During the 2005-06 GalAPAGoS expedition, acoustic and plume sensor surveys were conducted across the Galapagos ridge- hotspot intersection, lon. 94.5ºW- lon. 89.5ºW, to map fine scale geologic features and locate hydrothermal plumes emanating from the ridge crest. Where significant plumes were detected, the Medea fiber-optic camera sled was used successfully to find and image high-temperature vents on the seafloor. With Medea we discovered and imaged the first active and recently extinct black smokers known along the entire Galapagos Spreading Center (GSC), and documented the geologic setting of these vents. The Medea survey imaged numerous inactive vents as well as 3 active high-temperature vent fields along the ridge at 94º 04.5'W (Navidad Site), 91º56.2'W (Iguanas Site) and 91º54.3'W (Pinguinos Site). Two recently extinct vent fields also were identified at 91º23.4'-23.7'W and 91º13.8'W. All of the high-temperature vent sites that we identified along the GSC are found above relatively shallow AMC reflectors and are located in the middle 20% of ridge segments. Without exception the vent sites are located along fissures atop constructional axial volcanic ridges (AVR's) composed of relatively young pillow basalts. In some cases, the vents were associated with collapses adjacent to the fissures. The fissures appear to be eruptive sources of the pillow lavas comprising the AVR's. Video images of the chimneys show mature, cylindrical structures, up to 14m high; little diffuse flow; few animals; and some worm casts and dead clam shells, suggesting prior habitation. We conclude that distribution of the vents is controlled by magmatic processes, (i.e., by locations of shallow AMC magma reservoirs and eruptive fissures above dike intrusions), and that there is surprising similarity in the settings of the vents and the apparent ages of the chimneys and lavas along ~400 n.m of the GSC spanning the Galapagos mantle plume.

Anderson, P.; Haymon, R.; MacDonald, K.; White, S.

2006-12-01

269

Thermococcus thioreducens sp. nov., a novel hyperthermophilic, obligately sulfur-reducing archaeon from a deep-sea hydrothermal vent.  

PubMed

A hyperthermophilic, sulfur-reducing, organo-heterotrophic archaeon, strain OGL-20P(T), was isolated from 'black smoker' chimney material from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge (36.2 degrees N, 33.9 degrees W). The cells of strain OGL-20P(T) have an irregular coccoid shape and are motile with a single flagellum. Growth was observed within a pH range of 5.0-8.5 (optimum pH 7.0), an NaCl concentration range of 1-5 % (w/v) (optimum 3 %) and a temperature range of 55-94 degrees C (optimum 83-85 degrees C). The novel isolate is strictly anaerobic and obligately dependent upon elemental sulfur as an electron acceptor, but it does not reduce sulfate, sulfite, thiosulfate, Fe(III) or nitrate. Proteolysis products (peptone, bacto-tryptone, Casamino acids and yeast extract) are utilized as substrates during sulfur reduction. Strain OGL-20P(T) is resistant to ampicillin, chloramphenicol, kanamycin and gentamicin, but sensitive to tetracycline and rifampicin. The G+C content of the DNA is 52.9 mol%. The 16S rRNA gene sequence analysis revealed that strain OGL-20P(T) is closely related to Thermococcus coalescens and related species, but no significant homology by DNA-DNA hybridization was observed between those species and the new isolate. On the basis of physiological and molecular properties of the new isolate, we conclude that strain OGL-20P(T) represents a new separate species within the genus Thermococcus, for which we propose the name Thermococcus thioreducens sp. nov. The type strain is OGL-20P(T) (=JCM 12859(T)=DSM 14981(T)=ATCC BAA-394(T)). PMID:17625204

Pikuta, Elena V; Marsic, Damien; Itoh, Takashi; Bej, Asim K; Tang, Jane; Whitman, William B; Ng, Joseph D; Garriott, Owen K; Hoover, Richard B

2007-07-01

270

Geochemistry of Champagne Hot Springs shallow hydrothermal vent field and associated sediments, Dominica, Lesser Antilles  

Microsoft Academic Search

The Champagne Hot Springs (CHS) shallow submarine hydrothermal system is located along the submerged flank of the Plat Pays volcanic system on the southwest section of the island of Dominica, Lesser Antilles. We have conducted a detailed geochemical study of the hydrothermal system, with the objectives to investigate the source of the hydrothermal fluids and gases, their effect on sediment

Kevin T. McCarthy; Thomas Pichler; Roy E. Price

2005-01-01

271

Mineralized iron oxidizing bacteria from hydrothermal vents: targeting biosignatures on Mars  

Microsoft Academic Search

Putative hydrothermal systems have been identified on Mars based on orbital imagery and rover-based analyses. Based on Earth analogs, hydrothermal systems on Mars would be highly attractive for their potential for preserving organic and inorganic biosignatures. For example, iron oxidizing bacteria are ubiquitous in marine and terrestrial hydrothermal systems, where they often display distinctive cell morphologies and are commonly encrusted

R. J. Leveille

2010-01-01

272

The Majority of Free-Living Autotrophic Bacteria use the Reductive TCA Cycle for Carbon Fixation at Deep-Sea Hydrothermal Vents  

NASA Astrophysics Data System (ADS)

Deep-sea hydrothermal vents support large micro and macroscopic communities, without the input of photosynthesis. Autotrophic production at these vents is based on hydrothermal vent fluid chemistry. Primary production has been thought to occur mainly via hydrogen sulfide oxidation through the Calvin-Benson pathway, as measured by the presence of Rubisco in endosymbionts of several invertebrate hosts. Recently, we characterized two fosmids from a large insert library of the epsilon Proteobacterial episymbionts of Alvinella pompejana. Both contained sequences encoding ATP citrate lyase, a key enzyme in the reverse TCA cycle, an alternate carbon dioxide fixation pathway. Previous investigators have demonstrated the dominance of the epsilon subdivision in the free-living bacterial communities at hydrothermal vents. Based on these results, our working hypothesis is: The rTCA cycle is the dominant pathway for carbon fixation in the free-living bacterial communities at hydrothermal vents. A selection of free-living bacterial communities from various geographic locations (9N, East Pacific Rise and Guaymas Basin) were screened for the presence, diversity and expression (via RT-PCR) of Rubisco (forms I and II) and ATP citrate lyase. Our results indicate that the ATP citrate lyase gene is diverse and is consistently expressed in several types of vent communities. The two forms of Rubisco are not consistently present or expressed in the same environments. These results indicate that chemoautotrophic production in the free-living bacterial communities at deep-sea hydrothermal vents is dominated by bacteria that utilize the rTCA cycle, and parallels the phylogenetic dominance of members of the epsilon subdivision of Proteobacteria.

Campbell, B. J.; Cary, C.

2003-12-01

273

Macrozooplankton of a deep sea hydrothermal vent: In situ rates of oxygen consumption  

Microsoft Academic Search

Oxygen consumption rates of mixed macrozooplankton from the vicinity of a deep sea hydro- thermal vent system were measured with a three-chambered slurp-gun respirometer manipulated by the submersible Alvin at one vent station, clam acres (2,615-m depth), on the axis of the East Pacific Rise at 2 1\\

K. L. JR SMITH

1985-01-01

274

Field distribution and sulphide tolerance of Capitella capitata (Annelida: Polychaeta) around shallow water hydrothermal vents off Milos (Aegean Sea). A new sibling species?  

Microsoft Academic Search

The cosmopolitan polychaete Capitella capitata, known as a complex of opportunistic sibling species, usually dominates the macrobenthos of polluted or unpredictable environments.\\u000a A population of C. capitata, termed Capitella sp. M, was found in a shallow water hydrothermal vent area south of Milos (Greece). Here, this population occurs close to\\u000a vent outlets (termed the “transition zone”), an environment with steep

I. Gamenick; M. Abbiati; O. Giere

1998-01-01

275

Cu- and Zn-isotope systematics of seafloor hydrothermal vent fluids from a back-arc setting (Manus Basin)  

NASA Astrophysics Data System (ADS)

Unique seafloor hydrothermal processes combine in back-arc basins (BAB) to produce a wide range of vent fluid chemistry and mineral deposits, which are generally considered as critically important for the genesis of volcanogenic massive sulfide ore deposits. While it has become apparent that volatile-rich magmatic fluids play a crucial role in many BAB hydrothermal systems, the source of metals to the vent fluids, including ore-forming metals such as Cu, Zn and precious metals such as Ag and Au, has been a matter of debate [1]. Here, we applied coupled Cu and Zn stable isotopes to delineate if metal enrichment patterns in back-arc hydrothermal systems reflect (1) water-rock reactions with felsic host rock at low pH, (2) direct input of metal-rich magmatic volatiles, (3) remobilization from previously deposited sulfide or enriched source rock compositions. We measured Cu and Zn isotope composition of hydrothermal fluids from ten vents located in the eastern Manus BAB, Papua New Guinea (cruise MLGN06MV, R/V Melville, ROV Jason II). Purified samples were measured by MC-ICP-MS (Neptune) at IFREMER and data were corrected from instrumental mass bias using internal normalization [2], with an overall precision of 0.03‰ (2s). Cu isotopic ratios were reported relative to the NIST SRM 976 standard while Zn isotopic ratios were reported relative to IRMM 3702, having a ?66Zn value of 0.3‰ relative to Lyon-JMC standard. For the first time, Cu isotope composition of seafloor hydrothermal fluids were investigated and results show systematic enrichment in heavy Cu isotopes relative to basalt values (?65CuNIST976= 0.3‰ +/- 0.2‰, n=30). In general, the variations of ?65Cu values in hydrothermal fluids are consistent with ?65Cu values in chalcopyrite lining hydrothermal chimneys. In some case, heavier ?65Cu values of Cu-sulfides related to Cu in the fluids are interpreted to result from Cu-isotope fractionation during Cu oxidation and precipitation within local chimney environments. Zn isotope compositions are also heavier than basalt values (?66ZnJMC ranging from -0.04 to 0.94‰) but lack any correlation with ?65Cu values. Those values are in the same range of the East Pacific Rise vent fluids (?66ZnJMC=0.00 - 1.04‰ [3]) and show a similar negative correlation with the fluid temperature. Overall, the variability of both ?66Zn and ?65Cu are interpreted to result mostly from sub-seafloor precipitation/redissolution processes, rather than evaporation/condensation of metal-rich magmatic fluid at depth. [1] K. Yang, S.D. Scott, Nature 383, 420 (1996). [2] C.N. Maréchal, P. Télouk, F. Albarède, Chem. Geol. 156, 251 (1999). [3] S.G. John, O.J. Rouxel, P.R. Craddock, A.M. Engwall, E.A. Boyle, Earth Planet. Sci. Lett. 269, 17 (2008).

Dekov, V.; Rouxel, O.

2012-04-01

276

Retinal anatomy of a new species of bresiliid shrimp from a hydrothermal vent field on the Mid-Atlantic Ridge.  

PubMed

A new species of shrimp (Rimicaris sp.) was recently collected from the Snake Pit hydrothermal vent field on the Mid-Atlantic Ridge. Until the discovery in 1989 that the deep-sea, hydrothermal vent species, Rimicaris exoculata, possessed a hypertrophied dorsal eye, everyone believed that animals recovered from vent environments were blind. Like R. exoculata, Rimicaris sp., a small orange bresiliid shrimp, has an enlarged dorsal eye specialized for detecting light in a very dim environment instead of the expected compound eye. The individual lenses characteristic of a compound eye adapted for imaging have been replaced in Rimicaris sp. by a smooth cornea underlain by a massive array of photosensitive membrane. The number of ommatidia in this species is about the same as in shrimp species that live at the surface; however, the photoreceptors are larger in the deep-sea species and the shape of the photoreceptors is markedly different. The light-sensitive region of the photoreceptor is much larger than those of other shrimp and the rest of the receptor is much smaller than normal. All screening pigment has moved out of the path of incident light to a position below the retina, and the reflecting pigment cells have adapted to form a bright white diffusing screen between and behind the photoreceptors. The ultrastructure of the microvillar array comprising the rhabdom is typical for decapod crustaceans; however, there is a much greater volume density of rhabdom (80% to 85%) than normal. There is no ultrastructural evidence for cyclic rhabdom shedding or renewal. Rimicaris sp. has apparently adapted its visual system to detect the very dim light emitted from the throats of the black smoker chimneys around which it lives. PMID:8852633

Nuckley, D J; Jinks, R N; Battelle, B A; Herzog, E D; Kass, L; Renninger, G H; Chamberlain, S C

1996-02-01

277

Getting the bigger picture: Using precision Remotely Operated Vehicle (ROV) videography to acquire high-definition mosaic images of newly discovered hydrothermal vents in the Southern Ocean  

NASA Astrophysics Data System (ADS)

Direct visual observations from submersible vehicles at hydrothermal vents typically only reveal a fraction of the vent environment at any one time. We describe the use of precision Remotely Operated Vehicle (ROV) videography to produce extensive mosaic images of hydrothermal vent chimneys and surrounding seafloor areas (c. 250 m2), with sufficient resolution to determine distributions of macro- and megafauna. Doppler velocity log navigation (DVLNAV) was used to follow overlapping vertical survey lines in a fixed plane facing a vent chimney, while acquiring high-definition video imagery using a forward-looking camera. The DVLNAV also enabled the vehicle to follow overlapping horizontal survey lines while acquiring seafloor imagery from a downward-looking video camera and mapping variations in seawater temperature. Digital stills images extracted from video were used to compile high-resolution composite views of the surveyed areas. Applying these image acquisition techniques at vent fields on the East Scotia Ridge, Southern Ocean, revealed consistent patterns of faunal zonation around vent sources, variations in proportions of faunal assemblage types on different faces of a vent chimney, and differences in proportions of faunal assemblages between two different vent fields. The technique can therefore be used to determine the composition and spatial distribution of fauna across complex areas of topography, such as vent fields, where mosaic images of vertical structures cannot currently be acquired using other platforms such as autonomous underwater vehicles (AUVs). These image acquisition techniques, demonstrated here in the first ROV dives at newly discovered vent fields, may offer an appropriate technology for rapid baseline studies required by the potential mining of seafloor massive sulfides (SMS).

Marsh, Leigh; Copley, Jonathan T.; Huvenne, Veerle A. I.; Tyler, Paul A.; Isis ROV Facility

2013-08-01

278

Getting the bigger picture: Using precision Remotely Operated Vehicle (ROV) videography to acquire high-definition mosaic images of newly discovered hydrothermal vents in the Southern Ocean  

NASA Astrophysics Data System (ADS)

Direct visual observations from submersible vehicles at hydrothermal vents typically only reveal a fraction of the vent environment at any one time. We describe the use of precision Remotely Operated Vehicle (ROV) videography to produce extensive mosaic images of hydrothermal vent chimneys and surrounding seafloor areas (c. 250m2), with sufficient resolution to determine distributions of macro- and megafauna. Doppler velocity log navigation (DVLNAV) was used to follow overlapping vertical survey lines in a fixed plane facing a vent chimney, while acquiring high-definition video imagery using a forward-looking camera. The DVLNAV also enabled the vehicle to follow overlapping horizontal survey lines while acquiring seafloor imagery from a downward-looking video camera and mapping variations in seawater temperature. Digital stills images extracted from video were used to compile high-resolution composite views of the surveyed areas. Applying these image acquisition techniques at vent fields on the East Scotia Ridge, Southern Ocean, revealed consistent patterns of faunal zonation around vent sources, variations in proportions of faunal assemblage types on different faces of a vent chimney, and differences in proportions of faunal assemblages between two different vent fields. The technique can therefore be used to determine the composition and spatial distribution of fauna across complex areas of topography, such as vent fields, where mosaic images of vertical structures cannot currently be acquired using other platforms such as autonomous underwater vehicles (AUVs). These image acquisition techniques, demonstrated here in the first ROV dives at newly discovered vent fields, may offer an appropriate technology for rapid baseline studies required by the potential mining of seafloor massive sulfides (SMS).

Marsh, Leigh; Copley, Jonathan T.; Huvenne, Veerle A. I.; Tyler, Paul A.; the Isis ROV Facility

2013-08-01

279

Hydrothermal and magmatic couplings at mid-ocean ridges : controls on the locations of high-temperature hydrothermal vent fields  

NASA Astrophysics Data System (ADS)

The heat output and thermal regime of oceanic spreading centers are strongly controlled by boundary layer processes between the hydrothermal system and the underlying crustal magma chamber, which remain to be fully understood. In thermal models, the dynamical interactions between the hydrothermal system and the deeper part of the lithosphere affected by processes such as magma chamber convection, magma crystallization and latent heat release, or simple conduction, is usually not considered and a ad-hoc temperature or heat flux is prescribed at the base of the hydrothermal layer. In this work we develop original two-dimensional numerical models of the interactions between a shallow cellular hydrothermal (porous) system at temperatures <700°C in the upper crust, and a deeper magmatic (viscous) layer at temperatures up to 1200°C representing the lower crust. Our formalism allows for a dynamical interface between the two layers, which is fluctuating according to the dynamics of each layer. We systematically investigate the range of permeability and viscosity that characterized the dynamics of the porous and magmatic systems, respectively. An intriguing and highly debated question that we investigate is about the genesis of focused (i.e., kilometer-wide), hundreds-of-mega-watt (MW) powerfull, high-temperature (300-400°C) hydrothermal fields such as those discovered along the East Pacific Rise at 9°50'N or along the Juan de Fuca ridge/Endeavour segment for example. One hypothesis is that these fields require the formation of "elongated" hydrothermal convection cells that cool the crust on 5-10 kms, but the processes controlling the formation of such large aspect ratio (length/height) are poorly constrain. Our models show that such cells naturally arise from the dynamical coupling between a « low-viscosity », convecting lower-crust and a low-permeability upper hydrothermal layer. They also predict along-axis variations in the depth of the axial magma lens (AMC) seismic reflector of fast- and intermediate-spreading axes, and constrain lower oceanic crust cooling rates. They also suggest a dynamic link between upper oceanic crust along-axis permeability variations and stresses due to lower crust magmatic flow. We discuss the likelihood of this range of viscosity and permeability using available oceanic and ophiolites constraints and suggest that our work can motivate and help design future deep-sea experiments (e.g., drilling…).

Fontaine, Fabrice; Rabinowicz, Michel; Cannat, Mathilde; Escartin, Javier

2013-04-01

280

Discovery of Active Hydrothermal Sites Along the Mariana Volcanic Arc, Western Pacific Ocean  

NASA Astrophysics Data System (ADS)

Some 20,000 km of volcanic arcs, roughly one-third the total length of the global midocean ridge (MOR) system, rim the western Pacific Ocean. But compared to 25 years of hydrothermal investigations along MORs, exploration of similar activity on the estimated 600 submarine arc volcanoes is only beginning. In February 2003, as part of the Submarine Ring of Fire project funded by NOAA's Ocean Exploration Program, we made the first systematic survey of hydrothermal activity along the 1270-km-long Mariana intraoceanic volcanic arc, which lies almost entirely within the US EEZ. Prior fieldwork had documented active (but low-temperature) hydrothermal discharge on only three volcanoes: Kasuga 2, Kasuga 3, and Esmeralda Bank. During the cruise, we conducted 70 CTD operations over more than 50 individual volcanoes from 13° N to 23° N, plus a continuous CTD survey along 75 km of the back-arc spreading center (13° 15'N to 13° 41'N) adjacent to the southern end of the arc. We found evidence for active hydrothermal venting at 11 submarine volcanoes with summit (or caldera floor) depths ranging from 50 to 1550 m. Two additional sites were identified on the back-arc spreading center. Ongoing analyses of collected water samples could increase these totals. Our results confirmed continuing hydrothermal activity at Kasuga 2 (but not Kasuga 3) and Esmeralda Bank, in addition to newly discovered sites on nine other volcanoes. Many of these sites produce intense and widely dispersed plumes indicative of vigorous, high-temperature discharge. The volcanoes with active hydrothermal systems are about equally divided between those with and without summit calderas. The addition of the Marianas data greatly improves our view of hydrothermal sources along arcs. The 20,000 km of Pacific arcs can be divided between 6380 km of intraoceanic (i.e., mostly submarine) arcs and 13,880 km of island (i.e., mostly subaerial) arcs. At present, ˜15% of the total length of Pacific arcs has been surveyed thoroughly: 2550 km of intraoceanic arcs and 350 km of island arcs. Along the carefully studied intraoceanic arcs, 36 of 104 surveyed submarine volcanoes are hydrothermally active. Projecting these results along the unsurveyed intraoceanic arcs yields an expected total of an additional 54 active volcanoes. Island arcs will add additional sites, but are too poorly studied to admit a helpful estimate. For Pacific intraoceanic arcs, the predicted frequency of active volcanoes, about 1/66 km of arc length, is similar to the frequency of hydrothermal fields found along slow and ultra-slow MORs.

Baker, E. T.; Embley, R. W.; Resing, J. A.; Lupton, J. E.; Massoth, G. J.; de Ronde, C. E.; Nakamura, K.; Walker, S. L.

2003-12-01

281

Behavior of trace metals in the hydrothermal plume at two sites on the Izu-Bonin-Mariana Arc  

NASA Astrophysics Data System (ADS)

Deep-sea hydrothermal systems play an important role in the oceanic geochemical cycles of trace metals. High concentration of trace metals of the basalt origin is discharged into the deep sea via the hydrothermal plume. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. The processes of input and removal in the diffusing hydrothermal plume differ by individual hydrothermal systems. In this presentation, the behavior of trace metals in the hydrothermal plume of two sites on the Izu-Bonin-Mariana Arc is compared. This study was funded by the O`Archaean ParkO_L project of MEXT. The hydrothermal plume samples were taken from the Suiyo Seamount and the southern Mariana Trough (Pika Site). The mini CTDT-RMS mounted twelve 1.2L Niskin bottles was installed onto the manned submersible. And the hydrothermal plume samples were collected with monitoring the anomaly of temperature and turbidity. The samples were immediately filtered in an onboard clean bench. Unfiltered sample for analysis of total (particulate + dissolved) trace metal and filtered sample for analysis of dissolved trace metal were acidified. Trace metals (Al, Mn, Fe, Cu and Zn) in the hydrothermal plume samples were analyzed by GFAAS. The ranges of concentration of Al, Mn, Fe, Cu and Zn in the hydrothermal plume samples collected from two sites are _`15uM, _`5uM, _`5uM, _` 0.2uM and _`0.6uM, respectively. The particulate phase is predominant form in Al, Fe, Cu and Zn, and Mn shows the superiority of dissolved form. At the Suiyo Seamount, the hydrothermal active site is located in the bottom of caldera. On the other hand, the hydrothermal active site exists on the top of off-ridge seamount at the southern Mariana Trough. The diffusion process of trace metals in the hydrothermal plume to the ocean differed by the topographic factor in two sites. It suggests that trace metals discharged from the vents are hardly diffused to the ocean surmounting the Suiyo Seamount caldera because the metals almost removed from the hydrothermal plume in the caldera.

Shitashima, K.

2004-12-01

282

Toward a mechanistic understanding of larval dispersal: insights from genomic fingerprinting of the deep-sea hydrothermal vent tubeworm Riftia pachyptila  

Microsoft Academic Search

Larval dispersal is critical for the maintenance of species populations in patchy and ephemeral hydrothermal vent habitats. On fast-spreading ridges, such as the East Pacific Rise, rates of habitat turnover are comparable to estimated life- spans of many of the inhabiting species. Traditionally, dispersal questions have been addressed with two very different approaches, larval studies and popula- tion genetics. Population

Timothy M. Shank; Kenneth M. Halanych

2007-01-01

283

Diversity and distribution of subseafloor Thermococcales populations in diffuse hydrothermal vents at an active deep-sea volcano in the northeast Pacific Ocean  

Microsoft Academic Search

The presence, diversity, and distribution of a key group of subseafloor archaea, the Thermococcales, was examined in multiple diffuse flow hydrothermal vents at Axial Seamount, an active deep-sea volcano located in the northeast Pacific Ocean. A polymerase chain reaction (PCR) approach was used to determine if this group of subseafloor indicator organisms showed any phylogenetic distribution that may indicate distinct

Julie A. Huber; David A. Butterfield; John A. Baross

2006-01-01

284

Lipid biomarkers of deep-sea hydrothermal vent polychaetes— Alvinella pompejana, A. caudata, Paralvinella grasslei and Hesiolyra bergii  

NASA Astrophysics Data System (ADS)

The lipid composition was determined for 5 species of polychaete annelids collected by the Deep Submergence Vehicle ALVIN from high temperature chimneys at the 2500 m depth hydrothermal vent field of the East Pacific Rise. These are the first lipid biomarker analyses reported for these hydrothermal vent polychaetes. Lipid content was low in all samples (1.6-35.9 mg g -1 wet mass) and was dominated by polar lipid (78-90% of total lipid) with 8-19% sterol (ST), and very low storage lipid (triacylglycerol and wax ester). Total polyunsaturated fatty acids (PUFA) were moderately high (22-31% of total fatty acids (FA)) with extremely low or no docosahexaenoic acid (DHA, 22:6(n-3)). Eicosapentaenoic acid (EPA, 20:5(n-3)) levels were 5-6% in Alvinella pompejana and A. caudata and 10.3-13.7% in an errantiate polychaete (likely Hesionidae) and Hesiolyra bergii. There were greater PUFA and a greater EPA/AA (AA is arachidonic acid, 20:4(n-6)) ratio in the anterior versus the posterior half of A. pompejana, which may correlate to the strong temperature gradient reported in its tube. Total nonmethylene interrupted diunsaturated fatty acids (NMID) were 4-9% of total FA for most polychaete species and included several 20:2 and 22:2 components. The principal monounsaturated fatty acids (MUFA) included 18:1(n-7)c (14-19%), 16:1(n-7)c (2.6-10%) and 20:1(n-11)c (3-7% of total FA). These polychaete species may desaturate and elongate the bacterial-derived 18:1(n-7)c to obtain the essential FA EPA and AA. The major ST in the polychaetes is cholesterol (89-98% of total ST) with less cholesterol in the gut contents of A. pompejana. Other ST included 24-ethylcholesterol (1.5-5% of total ST) with lesser amounts of 24-methylenecholesterol, desmosterol, lathosterol, 24-methylcholesterol, 24-ethylcholesterol, and the stanols dehydrocholestanol and cholestanol. The high ST levels could play a role in thermal adaptation of membranes at the hydrothermal vent environment. Differences in the FA profiles separated the closely related species A. pompejana and A. caudata from Paralvinella grasslei, H. bergii, and the errantiate polychaete (likely Hesionidae).

Phleger, Charles F.; Nelson, Matthew M.; Groce, Ami K.; Craig Cary, S.; Coyne, Kathryn; Gibson, John A. E.; Nichols, Peter D.

2005-12-01

285

Vent fluid chemistry of the Rainbow hydrothermal system (36°N, MAR): Phase equilibria and in situ pH controls on subseafloor alteration processes  

NASA Astrophysics Data System (ADS)

The Rainbow hydrothermal field is located at 36°13.8'N-33°54.15'W at 2300 m depth on the western flank of a non-volcanic ridge between the South AMAR and AMAR segments of the Mid-Atlantic Ridge. The hydrothermal field consists of 10-15 active chimneys that emit high-temperature (˜365 °C) fluid. In July 2008, vent fluids were sampled during cruise KNOX18RR, providing a rich dataset that extends in time information on subseafloor chemical and physical processes controlling vent fluid chemistry at Rainbow. Data suggest that the Mg concentration of the hydrothermal end-member is not zero, but rather 1.5-2 mmol/kg. This surprising result may be caused by a combination of factors including moderately low dissolved silica, low pH, and elevated chloride of the hydrothermal fluid. Combining end-member Mg data with analogous data for dissolved Fe, Si, Al, Ca, and H 2, permits calculation of mineral saturation states for minerals thought appropriate for ultramafic-hosted hydrothermal systems at temperatures and pressures in keeping with constraints imposed by field observations. These data indicate that chlorite solid solution, talc, and magnetite achieve saturation in Rainbow vent fluid at a similar pH (T,P) (400 °C, 500 bar) of approximately 4.95, while higher pH values are indicated for serpentine, suggesting that serpentine may not coexist with the former assemblage at depth at Rainbow. The high Fe/Mg ratio of the Rainbow vent fluid notwithstanding, the mole fraction of clinochlore and chamosite components of chlorite solid solution at depth are predicted to be 0.78 and 0.22, respectively. In situ pH measurements made at Rainbow vents are in good agreement with pH (T,P) values estimated from mineral solubility calculations, when the in situ pH data are adjusted for temperature and pressure. Calculations further indicate that pH (T,P) and dissolved H 2 are extremely sensitive to changes in dissolved silica owing to constraints imposed by chlorite solid solution-fluid equilibria. Indeed, the predicted correlation between dissolved silica and H 2 defines a trend that is in good agreement with vent fluid data from Rainbow and other high-temperature ultramafic-hosted hydrothermal systems. We speculate that the moderate concentrations of dissolved silica in vent fluids from these systems result from hydrothermal alteration of plagioclase and olivine in the form of subsurface gabbroic intrusions, which, in turn are variably replaced by chlorite + magnetite + talc ± tremolite, with important implications for pH lowering, dissolved sulfide concentrations, and metal mobility.

Seyfried, W. E., Jr.; Pester, Nicholas J.; Ding, Kang; Rough, Mikaella

2011-03-01

286

Biocatalytic transformations of hydrothermal fluids  

NASA Astrophysics Data System (ADS)

The occurrence of copious animal populations at deep-sea vents indicates an effective microbial chemosynthetic biocatalysis of hydrothermal fluids on their emission into oxygenated ambient seawater. The large metabolic and physiological diversity of microbes found at these sites, including anaerobic and aerobic hyperthermophiles, reflects an even higher variety of biocatalytic or enzymatic reactions that greatly influence deep-sea hydrothermal geochemistry.

Jannasch, H. W.

287

Microbial Diversity of Indian Ocean Hydrothermal Vent Plumes: Microbes Tolerant of Desiccation, Peroxide Exposure, and Ultraviolet and ?-Irradiation  

NASA Astrophysics Data System (ADS)

The microbial diversity of Kali chimney plumes, part of a hydrothermal vent field in the Rodriguez Triple Junction, Indian Ocean (depth approximately 2,240 m), was examined in an attempt to discover ``extremotolerant'' microorganisms that have evolved unique resistance capabilities to this harsh environment. Water and sediment samples were collected from the vent and from sediments located at various distances (2-20 m) away from and surrounding the chimney. Samples were screened for hypertolerant microbes that are able to withstand multiple stresses. A total of 46 isolates were selected for exposure to a number of perturbations, such as heat shock, desiccation, H2O2, and ultraviolet (UV) and ?-irradiation. The survival of Psychrobacter sp. L0S3S-03b following exposure to >1,000 J/m2 UV254 radiation was particularly intriguing amid a background of varying levels of resistance. Vegetative cells of this non-spore-forming microbe not only survived all of the treatments, but also exhibited a 90% lethal dose of 30 s when exposed to simulated martian UV radiation and a 100% lethal dose of 2 min when exposed to full spectrum UV, which is comparable to findings for bacterial endospores.

La Duc, Myron T.; Benardini, James N.; Kempf, Michael J.; Newcombe, David A.; Lubarsky, Michael; Venkateswaran, Kasthuri

2007-05-01

288

Linking Hydrothermal Geochemistry to Organismal Physiology: Physiological Versatility in Riftia pachyptila from Sedimented and Basalt-hosted Vents  

PubMed Central

Much of what is known regarding Riftia pachyptila physiology is based on the wealth of studies of tubeworms living at diffuse flows along the fast-spreading, basalt-hosted East Pacific Rise (EPR). These studies have collectively suggested that Riftia pachyptila and its chemoautotrophic symbionts are physiologically specialized, highly productive associations relying on hydrogen sulfide and oxygen to generate energy for carbon fixation, and the symbiont's nitrate reduction to ammonia for energy and biosynthesis. However, Riftia also flourish in sediment-hosted vents, which are markedly different in geochemistry than basalt-hosted systems. Here we present data from shipboard physiological studies and global quantitative proteomic analyses of Riftia pachyptila trophosome tissue recovered from tubeworms residing in the EPR and the Guaymas basin, a sedimented, hydrothermal vent field. We observed marked differences in symbiont nitrogen metabolism in both the respirometric and proteomic data. The proteomic data further suggest that Riftia associations in Guaymas may utilize different sulfur compounds for energy generation, may have an increased capacity for energy storage, and may play a role in degrading exogenous organic carbon. Together these data reveal that Riftia symbionts are far more physiologically plastic than previously considered, and that -contrary to previous assertions- Riftia do assimilate reduced nitrogen in some habitats. These observations raise new hypotheses regarding adaptations to the geochemical diversity of habitats occupied by Riftia, and the degree to which the environment influences symbiont physiology and evolution.

Robidart, Julie C.; Roque, Annelys; Song, Pengfei; Girguis, Peter R.

2011-01-01

289

Finding immune gene expression differences induced by marine bacterial pathogens in the deep-sea hydrothermal vent mussel Bathymodiolus azoricus  

NASA Astrophysics Data System (ADS)

The deep-sea hydrothermal vent mussel Bathymodiolus azoricus lives in a natural environment characterized by extreme conditions of hydrostatic pressure, temperature, pH, high concentrations of heavy metals, methane and hydrogen sulphide. The deep-sea vent biological systems represent thus the opportunity to study and provide new insights into the basic physiological principles that govern the defense mechanisms in vent animals and to understand how they cope with microbial infections. Hence, the importance of understanding this animal's innate defense mechanisms, by examining its differential immune gene expressions toward different pathogenic agents. In the present study, B. azoricus mussels were infected with single suspensions of marine bacterial pathogens, consisting of Vibrio splendidus, Vibrio alginolyticus, or Vibrio anguillarum, and a pool of these Vibrio strains. Flavobacterium suspensions were also used as an irrelevant bacterium. Gene expression analyses were carried out using gill samples from animals dissected at 12 h and 24 h post-infection times by means of quantitative-Polymerase Chain Reaction aimed at targeting several immune genes. We also performed SDS-PAGE protein analyses from the same gill tissues. We concluded that there are different levels of immune gene expression between the 12 h and 24 h exposure times to various bacterial suspensions. Our results from qPCR demonstrated a general pattern of gene expression, decreasing from 12 h over 24 h post-infection. Among the bacteria tested, Flavobacterium is the microorganism species inducing the highest gene expression level in 12 h post-infections animals. The 24 h infected animals revealed, however, greater gene expression levels, using V. splendidus as the infectious agent. The SDS-PAGE analysis also pointed at protein profile differences between 12 h and 24 h, particularly around a protein area, of 18 KDa molecular mass, where most dissimilarities were found. Multivariate analyses demonstrated that immune genes, as well as experimental infections, clustered in discrete groups in accordance with the patterns observed in gene expression changes induced by bacterial pathogens.

Martins, E.; Queiroz, A.; Serrão Santos, R.; Bettencourt, R.

2013-02-01

290

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

PubMed Central

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.

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

291

Comparison of pyrite (FeS2) synthesis mechanisms to reproduce natural FeS2 nanoparticles found at hydrothermal vents  

NASA Astrophysics Data System (ADS)

Here we report the synthesis of pyrite in micrometer and nanometer sizes and with varied morphology. The purpose of these syntheses was to mimic natural pyrite nanoparticles recently found at hydrothermal vents, and to better understand the formation processes of these nano and micrometer sized particles. The duration of synthesis, surfactant used, and chemical mechanism of pyrite formation were all found to have an effect on resultant size and morphology. Yields of pyrite were sometimes low as our goal was to stop growth quickly after nucleation, in order to mimic hot vent fluids (350 °C) emanating to cold ocean bottom waters (2 °C). Natural nanoparticles forming under these conditions have currently been identified at diverse hydrothermal vents including Lau Basin, the Mid Atlantic Ridge (MAR), and the East Pacific Rise (EPR). These natural nanoparticles were variable in size and morphology, with aggregates of 50-350 nm diameter being the most prevalent. Syntheses occurring via the H2S pathway mimicked natural nanoparticles more closely than syntheses via the polysulfide pathway. One synthesis reported is suggestive of a pyrite/pyrrhotite equilibrium, indicating that we have succeeded in mimicking redox conditions similar to those that occur at certain hydrothermal vents.

Gartman, Amy; Luther, George W.

2013-11-01

292

Bioavailability, Bioaccumulation and Biotransformation of arsenic in coral reef organisms surrounding an arsenic-rich marine shallow-water hydrothermal vent system in the coastal waters of Ambitle Island, Papua New Guinea  

Microsoft Academic Search

Marine shallow-water hydrothermal systems are often enriched in biologically toxic elements, thus making them ideal natural analogs for coastal anthropogenic pollution. Here, we report our investigation of the bioavailability, bioaccumulation, and biotransformation of hydrothermally-derived arsenic into several coral reef organisms from the arsenic-rich marine shallow-water hydrothermal system of Tutum Bay, Ambitle Island, in northeastern Papua New Guinea. Hydrothermal venting provided

T. Pichler; D. Wallschläger; R. E. Price

2009-01-01

293

Thermophily in the Geobacteraceae: Geothermobacter ehrlichii gen. nov., sp. nov., a Novel Thermophilic Member of the Geobacteraceae from the "Bag City" Hydrothermal Vent  

PubMed Central

Little is known about the microbiology of the “Bag City” hydrothermal vent, which is part of a new eruption site on the Juan de Fuca Ridge and which is notable for its accumulation of polysaccharide on the sediment surface. A pure culture, designated strain SS015, was recovered from a vent fluid sample from the Bag City site through serial dilution in liquid medium with malate as the electron donor and Fe(III) oxide as the electron acceptor and then isolation of single colonies on solid Fe(III) oxide medium. The cells were gram-negative rods, about 0.5 ?m by 1.2 to 1.5 ?m, and motile and contained c-type cytochromes. Analysis of the 16S ribosomal DNA (rDNA) sequence of strain SS015 placed it in the family Geobacteraceae in the delta subclass of the Proteobacteria. Unlike previously described members of the Geobacteraceae, which are mesophiles, strain SS015 was a thermophile and grew at temperatures of between 35 and 65°C, with an optimum temperature of 55°C. Like many previously described members of the Geobacteraceae, strain SS015 grew with organic acids as the electron donors and Fe(III) or nitrate as the electron acceptor, with nitrate being reduced to ammonia. Strain SS015 was unique among the Geobacteraceae in its ability to use sugars, starch, or amino acids as electron donors for Fe(III) reduction. Under stress conditions, strain SS015 produced copious quantities of extracellular polysaccharide, providing a model for the microbial production of the polysaccharide accumulation at the Bag City site. The 16S rDNA sequence of strain SS015 was less than 94% similar to the sequences of previously described members of the Geobacteraceae; this fact, coupled with its unique physiological properties, suggests that strain SS015 represents a new genus in the family Geobacteraceae. The name Geothermobacter ehrlichii gen. nov., sp. nov., is proposed (ATCC BAA-635 and DSM 15274). Although strains of Geobacteraceae are known to be the predominant Fe(III)-reducing microorganisms in a variety of Fe(III)-reducing environments at moderate temperatures, strain SS015 represents the first described thermophilic member of the Geobacteraceae and thus extends the known environmental range of this family to hydrothermal environments.

Kashefi, Kazem; Holmes, Dawn E.; Baross, John A.; Lovley, Derek R.

2003-01-01

294

Hydrothermal venting at Vailulu'u Seamount: The smoking end of the Samoan chain  

Microsoft Academic Search

The summit crater of Vailulu'u Seamount, the youngest volcano in the Samoan chain, hosts an active hydrothermal system with profound impact on the ocean water column inside and around its crater (2 km wide and 407 m deep at a 593 m summit depth). The turbidity of the ocean water reaches 1.4 NTU, values that are higher than in any

H. Staudigel; S. R. Hart; A. A. P. Koppers; C. Constable; R. Workman; M. Kurz; E. T. Baker

2004-01-01

295

Diking, Magma Lenses, and Location of Hydrothermal Sites at Mid-Ocean Ridges  

NASA Astrophysics Data System (ADS)

Magma chambers beneath fast spreading mid-oceanic ridges appear in the form of thin lenses in the cross- axis sections. Furthermore, the recent data indicate that such a magma lens also lies beneath the intermediate spreading rate Endeavor segment on the Juan de Fuca Ridge. This shape indicates that the pressurization of the magma chamber should result in the stress concentration near the tips of the lens while the rest of the host rock would be in the state of compression. It is likely, therefore, that if an episode of magma replenishment in the magma lens results in diking, the dikes will initiate near the lens tips. The further propagation of dikes can be described by the principles of fracture mechanics. Our calculations suggest that the dikes propagate almost vertically towards the seafloor from the lens tips. Because diking is likely to generate a region of high permeability near its margin in addition to heat, hydrothermal activity may be localized by diking events. This suggests that hydrothermal vent fields may be located above the tips of the magma lenses away from the ridge axis (i.e., in the cross-axis profile of the lens). Alternatively, the diking may result from solidification of the magma lens. Because the density of magma is lower then that for the fresh rock, crystallization leads to the pressure decrease in the lens. Consequently, the stress distribution in the host rock changes and becomes tensile in the middle part of the magma lens and compressive in the tip regions. In this scenario, the dikes are likely to initiate from the central areas and the hydrothermal sites would be more expected to occur above the central part of the magma lens. Comparing observations of the location of the hydrothermal sites with respect to the magma lens location may be useful for constraining the mechanisms of magma lens evolution. For example, the Salty Dawg hydrothermal site on the Endeavor segment appears to be located near the western tip of the seismically imaged magma lens. Our model suggests that the venting activity at this site may be localized by diking triggered by the lens pressurization. The fact that hydrothermal venting at the EPR occurs above the center of the magma lens suggets that the rapid hydrothermal cooling and magma crystallization in the lens may be important in controlling the permeability distribution at that site. As has recently been argued in the literature, the pressurization of the magma lens may be occuring by the dyking originating from the underlying, deep magma chambers (also with a lens shape). Our computations suggest this hypothesis. Furthermore, not only may these dykes pressurize overlying shallow magma lenses, but these can then also lead to the subsequent dyke propagation from the tips of these shallow lenses to the seafloor.

Sim, Y.; Germanovich, L. N.; Lowell, R. P.; Ramondenc, P.

2004-12-01

296

COMPARISON OF VENTED AND ABSOLUTE PRESSURE TRANSDUCERS FOR WATER-LEVEL MONITORING IN HANFORD SITE CENTRAL PLATEAU WELLS  

Microsoft Academic Search

Automated water-level data collected using vented pressure transducers deployed in Hanford Site Central Plateau wells commonly display more variability than manual tape measurements in response to barometric pressure fluctuations. To explain this difference, it was hypothesized that vented pressure transducers installed in some wells are subject to barometric pressure effects that reduce water-level measurement accuracy. Vented pressure transducers use a

MCDONALD JP

2011-01-01

297

Detection and phylogenetic analysis of the membrane-bound nitrate reductase (Nar) in pure cultures and microbial communities from deep-sea hydrothermal vents.  

PubMed

Over the past few years the relevance of nitrate respiration in microorganisms from deep-sea hydrothermal vents has become evident. In this study, we surveyed the membrane-bound nitrate reductase (Nar) encoding gene in three different deep-sea vent microbial communities from the East Pacific Rise and the Mid-Atlantic Ridge. Additionally, we tested pure cultures of vent strains for their ability to reduce nitrate and for the presence of the NarG-encoding gene in their genomes. By using the narG gene as a diagnostic marker for nitrate-reducing bacteria, we showed that nitrate reductases related to Gammaproteobacteria of the genus Marinobacter were numerically prevalent in the clone libraries derived from a black smoker and a diffuse flow vent. In contrast, NarG sequences retrieved from a community of filamentous bacteria located about 50 cm above a diffuse flow vent revealed the presence of a yet to be identified group of enzymes. 16S rRNA gene-inferred community compositions, in accordance with previous studies, showed a shift from Alpha- and Gammaproteobacteria to Epsilonproteobacteria as the vent fluids become warmer and more reducing. Based on these findings, we argue that Nar-catalyzed nitrate reduction is likely relevant in temperate and less reducing environments where Alpha- and Gammaproteobacteria are more abundant and where nitrate concentrations reflect that of background deep seawater. PMID:23889124

Pérez-Rodríguez, Ileana; Bohnert, Kenneth A; Cuebas, Mariola; Keddis, Ramaydalis; Vetriani, Costantino

2013-07-25

298

Diversity and distribution of subseafloor Thermococcales populations in diffuse hydrothermal vents at an active deep-sea volcano in the northeast Pacific Ocean  

NASA Astrophysics Data System (ADS)

The presence, diversity, and distribution of a key group of subseafloor archaea, the Thermococcales, was examined in multiple diffuse flow hydrothermal vents at Axial Seamount, an active deep-sea volcano located in the northeast Pacific Ocean. A polymerase chain reaction (PCR) approach was used to determine if this group of subseafloor indicator organisms showed any phylogenetic distribution that may indicate distinct subseafloor communities at vents with different physical and chemical characteristics. Targeted primers for the Thermococcales 16S rRNA (small subunit ribosomal RNA) gene and intergenic transcribed spacer (ITS) region were designed and applied to organisms filtered directly from a variety of diffuse flow vents. Thermococcales were amplified from 9 of 11 samples examined, and it was determined that the ITS region is a better phylogenetic marker than the 16S rRNA in defining consistent groups of closely related sequences. Results show a relationship between environmental clone distribution and source vent chemistry. The most highly diluted vents with elevated iron and alkalinity contained a distinct group of Thermococcales as defined by the ITS region, suggesting separate subseafloor Thermococcales populations at diffuse vents within the Axial caldera.

Huber, Julie A.; Butterfield, David A.; Baross, John A.

2006-12-01

299

Microbial Communities and Chemosynthesis in Yellowstone Lake Sublacustrine Hydrothermal Vent Waters  

PubMed Central

Five sublacustrine thermal spring locations from 1 to 109?m water depth in Yellowstone Lake were surveyed by 16S ribosomal RNA gene sequencing in relation to their chemical composition and dark CO2 fixation rates. They harbor distinct chemosynthetic bacterial communities, depending on temperature (16–110°C) and electron donor supply (H2S <1 to >100??M; NH3 <0.5 to >10??M). Members of the Aquificales, most closely affiliated with the genus Sulfurihydrogenibium, are the most frequently recovered bacterial 16S rRNA gene phylotypes in the hottest samples; the detection of these thermophilic sulfur-oxidizing autotrophs coincided with maximal dark CO2 fixation rates reaching near 9??M?C?h?1 at temperatures of 50–60°C. Vents at lower temperatures yielded mostly phylotypes related to the mesophilic gammaproteobacterial sulfur oxidizer Thiovirga. In contrast, cool vent water with low chemosynthetic activity yielded predominantly phylotypes related to freshwater Actinobacterial clusters with a cosmopolitan distribution.

Yang, Tingting; Lyons, Shawn; Aguilar, Carmen; Cuhel, Russell; Teske, Andreas

2011-01-01

300

Distribution of Microorganisms in Deep-Sea Hydrothermal Vent Chimneys Investigated by Whole-Cell Hybridization and Enrichment Culture of Thermophilic Subpopulations  

Microsoft Academic Search

The microbial community structure of hydrothermal vent chimneys was evaluated by the combined use of enrichment cultures and whole-cell hybridizations with fluorescently labeled 16S rRNA-based oligonucleotide probes. Chimneys were collected during the Microsmoke cruise on the Mid-Atlantic Ridge and were sub- sampled on board and stored under reduced conditions or fixed. For estimation of culturable thermophiles, selective media were inoculated

HERMIE J. M. HARMSEN; DANIEL PRIEUR; CHRISTIAN JEANTHON

1997-01-01

301

Aeropyrum camini sp. nov., a strictly aerobic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney.  

PubMed

A novel hyperthermophilic archaeon, designated strain SY1(T), was isolated from a deep-sea hydrothermal vent chimney sample collected from the Suiyo Seamount in the Izu-Bonin Arc, Japan, at a depth of 1385 m. The cells were irregular cocci (1.2 to 2.1 micro m in diameter), occurring singly or in pairs, and stained Gram-negative. Growth was observed between 70 and 97 degrees C (optimum, 85 degrees C; 220 min doubling time), pH 6.5 and 8.8 (optimum, pH 8.0), and salinity of 2.2 and 5.3 % (optimum, 3.5 %). It was a strictly aerobic heterotroph capable of growing on complex proteinaceous substrates such as yeast extract and tryptone. The G+C content of the genomic DNA was 54.4 mol%. Phylogenetic analysis based on the 16S rDNA sequence of the isolate indicated that the isolate was closely related to Aeropyrum pernix strain K1(T). However, no significant genetic relatedness was observed between them by DNA-DNA hybridization. On the basis of the molecular and physiological traits of the new isolate, the name Aeropyrum camini sp. nov. is proposed, with the type strain SY1(T) (=JCM 12091(T)=ATCC BAA-758(T)). PMID:15023940

Nakagawa, Satoshi; Takai, Ken; Horikoshi, Koki; Sako, Yoshihiko

2004-03-01

302

Novel, Attached, Sulfur-Oxidizing Bacteria at Shallow Hydrothermal Vents Possess Vacuoles Not Involved in Respiratory Nitrate Accumulation  

PubMed Central

Novel, vacuolate sulfur bacteria occur at shallow hydrothermal vents near White Point, Calif. There, these filaments are attached densely to diverse biotic and abiotic substrates and extend one to several centimeters into the surrounding environment, where they are alternately exposed to sulfidic and oxygenated seawater. Characterizations of native filaments collected from this location indicate that these filaments possess novel morphological and physiological properties compared to all other vacuolate bacteria characterized to date. Attached filaments, ranging in diameter from 4 to 100 ?m or more, were composed of cylindrical cells, each containing a thin annulus of sulfur globule-filled cytoplasm surrounding a large central vacuole. A near-complete 16S rRNA gene sequence was obtained and confirmed by fluorescent in situ hybridization to be associated only with filaments having a diameter of 10 ?m or more. Phylogenetic analysis indicates that these wider, attached filaments form within the gamma proteobacteria a monophyletic group that includes all previously described vacuolate sulfur bacteria (the genera Beggiatoa, Thioploca, and Thiomargarita) and no nonvacuolate genera. However, unlike for all previously described vacuolate bacteria, repeated measurements of cell lysates from samples collected over 2 years indicate that the attached White Point filaments do not store internal nitrate. It is possible that these vacuoles are involved in transient storage of oxygen or contribute to the relative buoyancy of these filaments.

Kalanetra, Karen M.; Huston, Sherry L.; Nelson, Douglas C.

2004-01-01

303

RESIDUE DRUM VENT FILTER MONITORING PROGRAM AT THE ROCKY FLATS ENVIRONMENTAL TECHNOLOGY SITE  

Microsoft Academic Search

Several thousand 55-gallon drums of residue material from past plutonium processing operations are being stored at the Rocky Flats Environmental Technology Site (RFETS). This stored material awaits stabilization, packaging for shipment to the Waste Isolation Pilot Plant for disposal, or packaging for shipment to other DOE sites for processing. Each of these drums is fitted with a vent filter to

Susan J. Eberlein; William V. Conner; George J. Havrilla; James A. Ledford; Karen A. Phillips

304

The complete mitochondrial genome sequence of the hydrothermal vent galatheid crab Shinkaia crosnieri (Crustacea: Decapoda: Anomura): A novel arrangement and incomplete tRNA suite  

PubMed Central

Background Metazoan mitochondrial genomes usually consist of the same 37 genes. Such genes contain useful information for phylogenetic analyses and evolution modelling. Although complete mitochondrial genomes have been determined for over 1,000 animals to date, hydrothermal vent species have, thus far, remained excluded due to the scarcity of collected specimens. Results The mitochondrial genome of the hydrothermal vent galatheid crab Shinkaia crosnieri is 15,182 bp in length, and is composed of 13 protein-coding genes, two ribosomal RNA genes and only 18 transfer RNA genes. The total AT content of the genome, as is typical for decapods, is 72.9%. We identified a non-coding control region of 327 bp according to its location and AT-richness. This is the smallest control region discovered in crustaceans so far. A mechanism of cytoplasmic tRNA import was addressed to compensate for the four missing tRNAs. The S. crosnieri mitogenome exhibits a novel arrangement of mitochondrial genes. We investigated the mitochondrial gene orders and found that at least six rearrangements from the ancestral pancrustacean (crustacean + hexapod) pattern have happened successively. The codon usage, nucleotide composition and bias show no substantial difference with other decapods. Phylogenetic analyses using the concatenated nucleotide and amino acid sequences of the 13 protein-coding genes prove consistent with the previous classification based upon their morphology. Conclusion The present study will supply considerable data of use for both genomic and evolutionary research on hydrothermal vent ecosystems. The mitochondrial genetic characteristics of decapods are sustained in this case of S. crosnieri despite the absence of several tRNAs and a number of dramatic rearrangements. Our results may provide evidence for the immigrating hypothesis about how vent species originate.

Yang, Jin-Shu; Yang, Wei-Jun

2008-01-01

305

Microbial control of silver mineralization at a sea-floor hydrothermal site on the northern Gorda Ridge  

USGS Publications Warehouse

THE Sea Cliff hydrothermal field, on the northern Gorda Ridge, contains mounds and chimneys of hydrothermally precipitated sulphide and sulphate minerals typical of sea-floor hydrothermal vent sites1. In addition, large areas of the sea floor are covered by subhorizontal hydrothermal crusts. Samples of the crust recovered by submersible are composed of intensely altered fragments of basalt and basaltic hyaloclastite cemented by amorphous silica and chalcedony with less abundant barite, and minor amounts of base-metal sulphide minerals2. Some surfaces of the crust were formerly colonized by bacterial mats, which are locally preserved by replacement and overgrowth of the bacterial filaments by metal sulphide minerals and amorphous silica. The bacterial filaments are selectively replaced by prousite (Ag3AsS3), pearceite3 (Ag14.7-XCu1.3+xAs2S11), chalcopyrite (CuFeS2) and rarely by galena (PbS). Our observations suggest that bacterially mediated processes selectively precipitate silver, arsenic and copper, and that biological processes may contribute to precious-metal enrichment in some sea-floor hydrothermal base-metal sulphide deposits.

Zierenberg, R. A.; Schiffman, P.

1990-01-01

306

Diversity of Ultramafic Hosted Hydrothermal Deposits on the Mid Atlantic Ridge: First Submersible Studies on Ashadze, Logatchev 2 and Krasnov Vent Fields During the Serpentine Cruise.  

NASA Astrophysics Data System (ADS)

During the Serpentine cruise (March 2007) we have explored and sampled, using the ROV Victor, new ultramafic hydrothermal fields between 13°N and 17°N on the Mid Atlantic Ridge (MAR). The Serpentine cruise was part of a 4 years cooperation agreement between France and Russia. Targets were Ashadze1 and 2 (12°58"N), Logatchev 1 (14°45"N) and 2 (14°43"N) and Krasnov (16°38"N) fields localized after several surface cruises of the R/V professor Logatchev. A significant portion of the dives was dedicated to detailed microbathymetry, 50 m and 20 m above the seafloor, and simultaneous physical and chemical plume studies and magnetic surveys. High resolution (30cm) maps were further used for geological, biological, microbiological and fluid sampling operations. The cruise identified three new very active black smoker fields (Ashadze 1 and 2, Logatchev 2) on serpentinized peridotites. One extensive low temperature inactive deposit (dominantly birnessite) was discovered 1 km east of the Logatchev 1 field. The basaltic hosted Krasnov field was inactive. The Ashadze 1 site at 4080m of water depth is the deepest active black smoker field so far known in the ocean. Inactive and basalt hosted sulfide chimneys (Ashadze 4) were found at the base of the rift valley at 4530 m. Extensive gravity sliding related to the emplacement of the ultramafic rocks is evident at all ultramafic sites (see abstract by Ondreas et al.). Fluids, enriched in H2 and hydrocarbon, confirm the originality of ultramafic environments (see abstract by Charlou et al.). Logatchev 2 is venting low salinity black smoker fluids indicating phase separation. In addition, its position 12 km off axis, moves from 8 (Logatchev 1) to 12 km the possibility to have off axis black smokers long the MAR. Basaltic hosted deposits are dominated by pyrite and silica at Krasnov (Fe:39%, Si:11%, Cu:2.2%, Zn:0.14%) and by sphalerite and pyrite at Ashadze 4 (Fe:24%, Si:1.5%, Cu:0.15%, isocubanite. Ashadze 1 (Fe:33%, Si:1.3%, Cu:14%, Zn:14%) and Logatchev 2 (Fe:20%, Si:3%, Cu:14%, Zn:23%) are enriched in sphalerite. New samples at Logatchev 1 confirm that copper is largely dominant at this site (Fe:29%, Si:3%, Cu:28%, Zn:4%). The Ashadze 2 field is unusual. A small active crater can be interpreted as a hydrothermal volcano built up with a mixture of carbonates and secondary copper sulfides and chlorides. Massive sulfide chimneys are associated with the active smokers at the center of the crater. Many inactive carbonates/sulfides mounds are also aligned along a N-S depression. Two types of hydrothermal deposits are observed: massive copper-rich sulfides associated with the black smokers and carbonate/sulfides chimneys. Average composition of hydrothermal deposits for the field is Fe:26%, Si:11%, Cu:11%, Zn:5%, Ca:8%. The dominant carbonate is aragonite, Mg-Calcite is rare, and talc is common. Comparisons with other ultramafic sites along the MAR will also bee presented.

Fouquet, Y.; Cherkashov, G.; Charlou, J.; Ondreas, H.; Cannat, M.; Bortnikov, N.; Silantiev, S.; Etoubleau, J.; Scientific Party Of The Serpentine Cruise

2007-12-01

307

Temperature resistance studies on the deep-sea vent shrimp Mirocaris fortunata  

Microsoft Academic Search

The shrimp Mirocaris fortunata is a hydrothermal vent species that is found at most vent-sites along the Mid- Atlantic Ridge. This endemic species is found across a hydrothermal gradient, with thermal conditions ranging from 2-9°C in ambient seawater to fairly warm values of about 25°C. We performed in vivo experiments on M. fortunata specimens originating from different sites and depths

Bruce Shillito; Nadine Le Bris; Stéphane Hourdez; Juliette Ravaux; Delphine Cottin; Jean-Claude Caprais; Didier Jollivet; Françoise Gaill; Quai St-Bernard; Batiment A

2006-01-01

308

Expression and putative function of innate immunity genes under in situ conditions in the symbiotic hydrothermal vent tubeworm Ridgeia piscesae.  

PubMed

The relationships between hydrothermal vent tubeworms and sulfide-oxidizing bacteria have served as model associations for understanding chemoautotrophy and endosymbiosis. Numerous studies have focused on the physiological and biochemical adaptations that enable these symbioses to sustain some of the highest recorded carbon fixation rates ever measured. However, far fewer studies have explored the molecular mechanisms underlying the regulation of host and symbiont interactions, specifically those mediated by the innate immune system of the host. To that end, we conducted a series of studies where we maintained the tubeworm, Ridgeia piscesae, in high-pressure aquaria and examined global and quantitative changes in gene expression via high-throughput transcriptomics and quantitative real-time PCR (qPCR). We analyzed over 32,000 full-length expressed sequence tags as well as 26 Mb of transcript sequences from the trophosome (the organ that houses the endosymbiotic bacteria) and the plume (the gas exchange organ in contact with the free-living microbial community). R. piscesae maintained under conditions that promote chemoautotrophy expressed a number of putative cell signaling and innate immunity genes, including pattern recognition receptors (PRRs), often associated with recognizing microbe-associated molecular patterns (MAMPs). Eighteen genes involved with innate immunity, cell signaling, cell stress and metabolite exchange were further analyzed using qPCR. PRRs, including five peptidoglycan recognition proteins and a Toll-like receptor, were expressed significantly higher in the trophosome compared to the plume. Although PRRs are often associated with mediating host responses to infection by pathogens, the differences in expression between the plume and trophosome also implicate similar mechanisms of microbial recognition in interactions between the host and symbiont. We posit that regulation of this association involves a molecular "dialogue" between the partners that includes interactions between the host's innate immune system and the symbiont. PMID:22701617

Nyholm, Spencer V; Song, Pengfei; Dang, Jeanne; Bunce, Corey; Girguis, Peter R

2012-06-11

309

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

PubMed

Organic osmolytes, solutes that regulate cell volume, occur at high levels in marine invertebrates. These are mostly free amino acids such as taurine, which are "compatible" with cell macromolecules, and methylamines such as trimethylamine oxide, which may have a nonosmotic role as a protein stabilizer, and which is higher in many deep-sea animals. To better understand nonosmotic roles of osmolytes, we used high-performance liquid chromatography and (1)H-nuclear magnetic resonance (NMR) to analyze vestimentiferans (vestimentum tissue) from unusual marine habitats. Species from deep hydrothermal vents were Riftia pachyptila of the East Pacific Rise (2,636 m) and Ridgeia piscesae of the Juan de Fuca Ridge (2,200 m). Species from cold hydrocarbon seeps were Lamellibrachia sp. and an unnamed escarpid species from subtidal sediment seeps (540 m) off Louisiana and Lamellibrachia barhami from bathyal tectonic seeps (1,800-2,000 m) off Oregon. Riftia were dominated by hypotaurine (152 mmol/kg wet wt), an antioxidant, and an unidentified solute with an NMR spectrum consistent with a methylamine. Ridgeia were dominated by betaine (N-trimethylglycine; 109 mmol/kg), hypotaurine (64 mmol/kg), and taurine (61 mmol/kg). The escarpids were dominated by taurine (138 mmol/kg) and hypotaurine (69 mmol/kg). Both Lamellibrachia populations were dominated by N-methyltaurine (209-252 mmol/kg), not previously reported as a major osmolyte, which may be involved in methane and sulfate metabolism. Trunk and plume tissue of the Oregon Lamellibrachia were nearly identical to vestimentum in osmolyte composition. The methylamines may also stabilize proteins against pressure; they were significantly higher in the three deeper-dwelling groups. PMID:11073799

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

310

Ocean ridge magmatic and hydrothermal geochemical processes  

NASA Astrophysics Data System (ADS)

The ocean ridge system as an interaction site linking the interior of the earth with the lithosphere, biosphere, and hydrosphere is characterized in a critical review of U.S. research from the period 1987-1990. Sections are devoted to magmatic and hydrothermal processes, with particular attention to the chemical variability of MORB, studies of magmatic segmentation in the East Pacific Rise, plans for sampling the Pacific-Antarctic Ridge, regional differences in the extent and pressure of melting, the diversity of oceanic plutonic rocks, observations of active hydrothermal venting, the composition of hydrothermal fluids, models of hydrothermal circulation, and the mineralogy and geochemistry of hydrothermal deposits. A comprehensive bibliography is provided.

Klein, Emily M.

311

Chromosomal and nuclear characteristics of deep-sea hydrothermal-vent organisms: correlates of increased growth rate  

Microsoft Academic Search

A range of tissue and cell types from adult and juvenile stages of vent- and non-vent-dwelling deep-sea and shallow-water organisms were compared for signs of cell division, in preparation for a cytogenetic study of the different groups. Virtually all the Mid-Atlantic Ridge (MAR) vent species (bresiliid shrimp, bathymodiolid mussel, branchipolynoid polychaete, and a range of small gastropods) showed an abundance

D. Dixon; L. Dixon; P. Pascoe; J. Wilson

2001-01-01

312

Purification and properties of a thermoactive and thermostable pullulanase from Thermococcushydrothermalis , a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent  

Microsoft Academic Search

The extremely thermophilic archaeon Thermococcus hydrothermalis, isolated from a deep-sea hydrothermal vent in the East Pacific Rise at 21°N, produced an extracellular pullulanase. This\\u000a enzyme was purified 97-fold to homogeneity from cell-free culture supernatant. The purified pullulanase was composed of a\\u000a single polypeptide chain having an estimated molecular mass of 110?kDa (gel filtration) or 128?kDa (sodium dodecyl sulfate\\/polyacryl\\u000a amide gel

H. Gantelet; F. Duchiron

1998-01-01

313

Bacterial Lifestyle in a Deep-sea Hydrothermal Vent Chimney Revealed by the Genome Sequence of the Thermophilic Bacterium Deferribacter desulfuricans SSM1  

PubMed Central

The complete genome sequence of the thermophilic sulphur-reducing bacterium, Deferribacter desulfuricans SMM1, isolated from a hydrothermal vent chimney has been determined. The genome comprises a single circular chromosome of 2 234 389 bp and a megaplasmid of 308 544 bp. Many genes encoded in the genome are most similar to the genes of sulphur- or sulphate-reducing bacterial species within Deltaproteobacteria. The reconstructed central metabolisms showed a heterotrophic lifestyle primarily driven by C1 to C3 organics, e.g. formate, acetate, and pyruvate, and also suggested that the inability of autotrophy via a reductive tricarboxylic acid cycle may be due to the lack of ATP-dependent citrate lyase. In addition, the genome encodes numerous genes for chemoreceptors, chemotaxis-like systems, and signal transduction machineries. These signalling networks may be linked to this bacterium's versatile energy metabolisms and may provide ecophysiological advantages for D. desulfuricans SSM1 thriving in the physically and chemically fluctuating environments near hydrothermal vents. This is the first genome sequence from the phylum Deferribacteres.

Takaki, Yoshihiro; Shimamura, Shigeru; Nakagawa, Satoshi; Fukuhara, Yasuo; Horikawa, Hiroshi; Ankai, Akiho; Harada, Takeshi; Hosoyama, Akira; Oguchi, Akio; Fukui, Shigehiro; Fujita, Nobuyuki; Takami, Hideto; Takai, Ken

2010-01-01

314

Susceptibility to Heavy Metals and Characterization of Heterotrophic Bacteria Isolated from Two Hydrothermal Vent Polychaete Annelids, Alvinella pompejana and Alvinella caudata  

PubMed Central

Specimens of alvinellid polychaetes and their tubes were collected in the Parigo hydrothermal vent field on the East Pacific Rise (13°N) in October and November 1987. Heterotrophic bacterial strains were isolated on metal-amended media from the tube and dorsal integument of one specimen of Alvinella pompejana, from the dorsal integument of another from the whole integument of a specimen of Alvinella caudata, and from undetermined alvinellid tubes. The strains were characterized and tested for susceptibility to five heavy metals by using a microdilution method for MIC determinations. All strains were gram-negative rods. Most of them were characterized by the ability to degrade Tween 80 and gelatin and to produce hydrogen sulfide from cysteine. Numerous strains, from all sample origins, displayed resistance to cadmium, zinc, arsenate, and silver and tolerated high amounts of copper. Metal resistance was exhibited by 92.3% of the total isolates. The occurrence of multiply resistant bacteria may demonstrate an adaptation of alvinellid-associated microflora to the general enrichment of metals in the hydrothermal vent environment. Images

Jeanthon, Christian; Prieur, Daniel

1990-01-01

315

On Possible Relationships Between Diking, Magma Lenses, and Location of Hydrothermal Sites at Mid-Ocean Ridges  

NASA Astrophysics Data System (ADS)

Magma chambers beneath fast spreading mid-oceanic ridges appear in the form of thin lenses in the cross- axis sections. Furthermore, the recent data indicate that such a magma lens also lies beneath the intermediate spreading rate Endeavor segment on the Juan de Fuca Ridge. This shape indicates that the pressurization of the magma chamber should result in the stress concentration near the tips of the lens while the rest of the host rock would be in the state of compression. It is likely, therefore, that if an episode of magma replenishment in the magma lens results in diking, the dikes will initiate near the lens tips. The further propagation of dikes can be described by the principles of fracture mechanics. Our calculations suggest that the dikes propagate almost vertically towards the seafloor from the lens tips. Because diking is likely to generate a region of high permeability near its margin in addition to heat, hydrothermal activity may be localized by diking events. This suggests that hydrothermal vent fields may be located above the tips of the magma lenses away from the ridge axis (i.e., in the cross-axis profile of the lens). Alternatively, the diking may result from solidification of the magma lens. Because the density of magma is lower then that for the fresh rock, crystallization leads to the pressure decrease in the lens. Consequently, the stress distribution in the host rock changes and becomes tensile in the middle part of the magma lens and compressive in the tip regions. In this scenario, the dikes are likely to initiate from the central areas and the hydrothermal sites would be more expected to occur above the central part of the magma lens. Comparing observations of the location of the hydrothermal sites with respect to the magma lens location may be useful for constraining the mechanisms of magma lens evolution. For example, the Salty Dawg hydrothermal site on the Endeavor segment appears to be located near the western tip of the seismically imaged magma lens. Our model suggests that the venting activity at this site may be localized by diking triggered by the lens pressurization.

Germanovich, L.; Sim, Y.; Lowell, R. P.

2003-12-01

316

Exploring the limit of metazoan thermal tolerance via comparative proteomics: thermally induced changes in protein abundance by two hydrothermal vent polychaetes  

PubMed Central

Temperatures around hydrothermal vents are highly variable, ranging from near freezing up to 300°C. Nevertheless, animals thrive around vents, some of which live near the known limits of animal thermotolerance. Paralvinella sulfincola, an extremely thermotolerant vent polychaete, and Paralvinella palmiformis, a cooler-adapted congener, are found along the Juan de Fuca Ridge in the northwestern Pacific. We conducted shipboard high-pressure thermotolerance experiments on both species to characterize the physiological adaptations underlying P. sulfincola's pronounced thermotolerance. Quantitative proteomics, expressed sequence tag (EST) libraries and glutathione assays revealed that P. sulfincola (i) exhibited an upregulation in the synthesis and recycling of glutathione with increasing temperature, (ii) downregulated nicotinamide adenine dinucleotide (NADH) and succinate dehydrogenases (key enzymes in oxidative phosphorylation) with increasing temperature, and (iii) maintained elevated levels of heat shock proteins (HSPs) across all treatments. In contrast, P. palmiformis exhibited more typical responses to increasing temperatures (e.g. increasing HSPs at higher temperatures). These data reveal differences in how a mesotolerant and extremely thermotolerant eukaryote respond to thermal stress, and suggest that P. sulfincola's capacity to mitigate oxidative stress via increased synthesis of antioxidants and decreased flux through the mitochondrial electron transport chain enable pronounced thermotolerance. Ultimately, oxidative stress may be the key factor in limiting all metazoan thermotolerance.

Dilly, Geoffrey F.; Young, C. Robert; Lane, William S.; Pangilinan, Jasmyn; Girguis, Peter R.

2012-01-01

317

Exploring the limit of metazoan thermal tolerance via comparative proteomics: thermally induced changes in protein abundance by two hydrothermal vent polychaetes.  

PubMed

Temperatures around hydrothermal vents are highly variable, ranging from near freezing up to 300°C. Nevertheless, animals thrive around vents, some of which live near the known limits of animal thermotolerance. Paralvinella sulfincola, an extremely thermotolerant vent polychaete, and Paralvinella palmiformis, a cooler-adapted congener, are found along the Juan de Fuca Ridge in the northwestern Pacific. We conducted shipboard high-pressure thermotolerance experiments on both species to characterize the physiological adaptations underlying P. sulfincola's pronounced thermotolerance. Quantitative proteomics, expressed sequence tag (EST) libraries and glutathione assays revealed that P. sulfincola (i) exhibited an upregulation in the synthesis and recycling of glutathione with increasing temperature, (ii) downregulated nicotinamide adenine dinucleotide (NADH) and succinate dehydrogenases (key enzymes in oxidative phosphorylation) with increasing temperature, and (iii) maintained elevated levels of heat shock proteins (HSPs) across all treatments. In contrast, P. palmiformis exhibited more typical responses to increasing temperatures (e.g. increasing HSPs at higher temperatures). These data reveal differences in how a mesotolerant and extremely thermotolerant eukaryote respond to thermal stress, and suggest that P. sulfincola's capacity to mitigate oxidative stress via increased synthesis of antioxidants and decreased flux through the mitochondrial electron transport chain enable pronounced thermotolerance. Ultimately, oxidative stress may be the key factor in limiting all metazoan thermotolerance. PMID:22553092

Dilly, Geoffrey F; Young, C Robert; Lane, William S; Pangilinan, Jasmyn; Girguis, Peter R

2012-05-02

318

Salinity, pressure and heavy-metal stress response of moderately halophilic bacteria isolated from hydrothermal-vent environments  

NASA Astrophysics Data System (ADS)

Moderately halophilic bacteria comprised 0.01-10% of the total microbial community in low-temperature hydrothermal emissions and in the overlying water column. The presence of these microorganisms was initially thought to be linked to brines that are produced by super-critical phase separation beneath deep-sea mid-ocean ridges. While there is conclusive evidence that these brines exist at extremely hot (>400°C) temperatures, it is difficult to construct geochemical and fluid-flow models which would delineate extensive subseafloor brine environments in mesophilic to hyperthermophilic temperature ranges. An alternative hypothesis is that halotolerance is actually induced by an environmental stress other than salt. Pressure and heavy metals are likely candidates. Diffuse flow environments at Axial Seamount and the Endeavour Segment of the Juan de Fuca Ridge and along the Southern East Pacific Rise are both elevated in concentrations of heavy metals and under moderate pressure (150-270 atm; higher beneath the seafloor). From these fluids we isolated numerous strains of moderately halophilic bacteria belonging to the genera Halomonas and Marinobacter. At ambient pressure, isolates grew between -1 and 40°C, with up to 25% NaCl, and with 2.0-3.0 mM cadmium. The isolates displayed widely varying pressure maxima and cell yields as a function of temperature and salinity. High pressure and salt (and heavy metals?) may independently induce a stress response that enables these bacteria to cope with all of these stresses. Also in progress are molecular-phylogenetic analyses of moderately halophilic bacterial populations from diffuse flow sites along the Juan de Fuca Ridge. We expect that many of the organisms detected using our novel primers will have been cultured. With the knowledge of their physiologies and how their diversity changes in relation to fluid chemistry, these data may shed light on the dynamic subseafloor hydrothermal system that supports them.

Kaye, J. Z.; Baross, J. A.

2002-12-01

319

Heat-shock response and temperature resistance in the deep-sea vent shrimp Rimicaris exoculata  

Microsoft Academic Search

The shrimp Rimicaris exoculata swarms around hydrothermal black smoker chimneys at most vent sites along the Mid-Atlantic Ridge. This species maintains close proximity to the hydrothermal fluid, where temperatures can reach 350°C and steep thermal and chemical gradients are expected. We performed in vivo experiments in pressurized aquaria to determine the upper thermal limit (critical thermal maximum (CTmax)) of R.

Juliette Ravaux; Françoise Gaill; Nadine Le Bris; Pierre-Marie Sarradin; Didier Jollivet; Bruce Shillito; Quai St-Bernard; Batiment A

2003-01-01

320

Three-dimensional seismic characterization of a venting site reveals compelling indications of natural hydraulic fracturing  

Microsoft Academic Search

Based on a three-dimensional high-resolution seismic survey off Vancouver Island, Canada, we show that natural hydraulic fracturing is an efficient process to create permeable pathways for focused fluid upflow at submarine venting sites. The pockmark structure examined in this study is located on top of an accreted ridge, where the low-permeability base of the gas hydrate stability field is also

L. Zühlsdorff; V. Spieß

2004-01-01

321

Deep-Sea Investigations on Hydrothermal Site Rainbow (MAR 36°14 N)  

Microsoft Academic Search

Hydrothermal site Rainbow, one of the few known site on an ultramafic basement, is an exceptional target for the multidisciplinary study of hydrothermal phenomena. It is one of the two targets of the MoMAR (Monitoring the Mid Atlantic Ridge) project patronized by InterRidge, and is the focus of an IODP drilling project. What makes this site exceptional is the abundance

J. Dyment; Y. Fouquet; P. Gente; B. Ildefonse; R. Thibaud; E. Hoise; D. Bissessur; V. Yatheesh; M. Scientific Party

2008-01-01

322

Constraints on 226Ra-210Pb Decoupling in Fast-Spreading Mid-Ocean Ridge Magma Systems from Hydrothermal Vent Fluid Compositions, 9°46'-9°52'N East Pacific Rise  

NASA Astrophysics Data System (ADS)

Though mid-ocean ridge magma systems are responsible for producing two-thirds of Earth's surface, the time scales associated with magma migration into and through these systems remain enigmatic. A recent study by Rubin et al.(1) made progress on this front using U-series techniques on mid-ocean ridge basalt (MORB) erupted in 1991 from the EPR 9°50'N. Their results suggest a 210Pb-226Ra- 230Th disequilibrium that, in a system closed since melting, would have taken only sixty-six years to form, significantly faster than most geophysical models have proposed. Hydrothermal vent fluid chemistry provides an ideal means of evaluating the relative significance of one important crustal process, radon degassing, which could potentially impact these U-series signatures. High levels of CO2 and 3He/heat in vent fluids collected in November 2003 and December 2004 from the 9°46'-9°52'N vent field area may be associated with shallow level magmatic degassing (2). If degassing occurs at shallow levels, Rn may partition into the convecting seawater, producing an in growth of 210Pb that is not supported by 226Ra decay. Excess 210Pb from vent fluids associated with the high CO2 would therefore be indicative of 222Rn fractionation from a shallow degassing magma source. Since the Pb content of vent fluids varies as a function of chlorinity, temperature and other parameters, the 210Pb data must be normalized to the concentrations of stable Pb in the fluids(3). During the last decade, regular sampling at the Ridge2000 Integrated Study Site (ISS) has provided a spatially diverse range of samples to characterize the evolution of vent fluid chemistry throughout the eruption cycle (1991-2006). This unique dataset includes samples collected before and after the 2005 eruption and represents the full range of CO2 at this site. Vent sites located at the maximum of the CO2 degassing signal (9°50.3'-50.8'N) range in 210Pb/Pb ratios of 1.15 to 5.68 dpm/?g. Those south of the degassing maximum (9°46.3'-47.2'N) are used to establish a non-degassing 210Pb/Pb range which ranges from 0.22 to 0.54 dpm/?g. Preliminary results show a positive trend between 210Pb/Pb ratios with end member CO2 concentrations, thereby implying that Rn degassing does occur at shallow levels and must be taken into consideration in melt ascent models based on U-series. (1) Rubin et al., Nature, 2005. (2) Lilley et al., Nature, 2003. (3) Von Damm, Annu. Rev. Earth Planet Sci., 1990.

Meana-Prado, M. F.; von Damm, K. L.; Bryce, J. G.; Lilley, M. D.; Dibb, J. E.

2008-12-01

323

Submarine hydrothermal activity and gold-rich mineralization at Brothers Volcano, Kermadec Arc, New Zealand  

Microsoft Academic Search

Brothers volcano, of the Kermadec intraoceanic arc, is host to a hydrothermal system unique among seafloor hydrothermal systems\\u000a known anywhere in the world. It has two distinct vent fields, known as the NW Caldera and Cone sites, whose geology, permeability,\\u000a vent fluid compositions, mineralogy, and ore-forming conditions are in stark contrast to each other. The NW Caldera site strikes\\u000a for

Cornel E. J. de Ronde; Gary J. Massoth; David A. Butterfield; Bruce W. Christenson; Junichiro Ishibashi; Robert G. Ditchburn; Mark D. Hannington; Robert L. Brathwaite; John E. Lupton; Vadim S. Kamenetsky; Ian J. Graham; Georg F. Zellmer; Robert P. Dziak; Robert W. Embley; Vesselin M. Dekov; Frank Munnik; Janine Lahr; Leigh J. Evans; Ken Takai

2011-01-01

324

Diversity of Microorganisms Associated With low Temperature Iron Deposits at the 71°N Hydrothermal Vent Field Along the Arctic Mid-Ocean Ridge  

NASA Astrophysics Data System (ADS)

Rust coloured mounds and chimney-like deposits of the newly discovered71°N hydrothermal vent fields at the south-western part of the Mohns Ridge have been investigated. Iron is the fourth most abundant element in the Earth's crust and thus represents one of the most abundant redox active metals widely available for microbial energy generation. Microbial Fe-oxidation is a widespread process in the deep-sea environments, but only recently have studies begun to elucidate these processes and describe the phylogenetic and physiological diversity of the microbial communities that mediate them. Therefore studying the process by which iron is oxidised and how this influence these cold deep-sea communities is of significant importance. We have studied the microbial communities present in these low-temperature rust coloured deposits in order to elucidate the phylogenetic and physiological diversity of the microbial populations inhabiting these deep-sea environments. Polyphasic characterisations by using geochemical and biological analyses have been performed. The deposited material has a highly porous microtexture of branching, twisted filaments resembling stalks of the iron- oxidising Gallionella sp, but numerous other unidentified filamentous structures were also found to be present. Phylogenetic analysis of clone libraries has so far demonstrated that the bacterial community is dominated by members of the Proteobacteria, Planctomycetes and Chloroflexi. The archaeal community consists of both Crenarchaeota and Euryarchaeota. The Crenarchaeota sequences affiliates with other reported uncultivated Deep-Sea archaeal sequences. To further investigate the ecological impact of these iron mounds and their interaction with microorganisms cultivation experiments have been applied. We are specifically focusing on enrichment of iron oxidizing bacteria. Preliminary results indicates that iron oxidizers related to the newly described Mariprofundus ferrooxidans as well as iron reducers related to Rhodoferax ferrireducens are present in these environments, but we have not yet been able to obtain pure isolates form this site. Strains isolated from these systems will provide an opportunity to explore the phylogenetic diversity of neutrophilic Fe metabolism and to establish model systems for molecular metabolic studies. Description of microbial communities existing under such characteristic sub-seafloor environments is important when understanding the role these communities play in the major biochemical processes.

Ovreas, L.; Johannessen, T.; Jorgensen, S.; Thorseth, I. H.; Pedersen, R. B.

2007-12-01

325

Complete genome sequence of Thermovibrio ammonificans HB-1T, a thermophilic, chemolithoautotrophic bacterium isolated from a deep-sea hydrothermal vent  

SciTech Connect

Thermovibrio ammonificans type strain HB-1T is a thermophilic (Topt: 75 C), strictly anaero- bic, chemolithoautotrophic bacterium that was isolated from an active, high temperature deep-sea hydrothermal vent on the East Pacific Rise. This organism grows on mineral salts medium in the presence of CO2/H2, using NO3- or S0 as electron acceptors, which are re- duced to ammonium or hydrogen sulfide, respectively. T. ammonificans is one of only three species within the genus Thermovibrio, a member of the family Desulfurobacteriaceae, and it forms a deep branch within the phylum Aquificae. Here we report the main features of the genome of T. ammonificans strain HB-1T (DSM 15698T).

Giovannelli, Donato [Rutgers University; Ricci, Jessica [Rutgers University; Perez-Rodriguez, Ileana [Rutgers University; Hugler, Michael [Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA; O'Brien, Charles [Rutgers University; Keddis, Ramaydalis [Rutgers University; Grosche, Ashley [Rutgers University; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Bruce, David [Los Alamos National Laboratory (LANL); Davenport, Karen W. [Los Alamos National Laboratory (LANL); Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Han, James [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Tapia, Roxanne [Los Alamos National Laboratory (LANL); Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Vetriani, Costantino [Rutgers University

2012-01-01

326

Complete genome sequence of the aerobic, heterotroph Marinithermus hydrothermalis type strain (T1T) from a deep-sea hydrothermal vent chimney  

PubMed Central

Marinithermus hydrothermalis Sako et al. 2003 is the type species of the monotypic genus Marinithermus. M. hydrothermalis T1T was the first isolate within the phylum “Thermus-Deinococcus” to exhibit optimal growth under a salinity equivalent to that of sea water and to have an absolute requirement for NaCl for growth. M. hydrothermalis T1T is of interest because it may provide a new insight into the ecological significance of the aerobic, thermophilic decomposers in the circulation of organic compounds in deep-sea hydrothermal vent ecosystems. This is the first completed genome sequence of a member of the genus Marinithermus and the seventh sequence from the family Thermaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,269,167 bp long genome with its 2,251 protein-coding and 59 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Copeland, Alex; Gu, Wei; Yasawong, Montri; Lapidus, Alla; Lucas, Susan; Deshpande, Shweta; Pagani, Ioanna; Tapia, Roxanne; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Sam; Liolios, Konstantinos; Ivanova, Natalia; Mavromatis, Konstantinos; Mikhailova, Natalia; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam; Pan, Chongle; Brambilla, Evelyne-Marie; Rohde, Manfred; Tindall, Brian J.; Sikorski, Johannes; Goker, Markus; Detter, John C.; Bristow, James; Eisen, Jonathan A.; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C.; Klenk, Hans-Peter; Woyke, Tanja

2012-01-01

327

Cauliform bacteria lacking phospholipids from an abyssal hydrothermal vent: proposal of Glycocaulis abyssi gen. nov., sp. nov., belonging to the family Hyphomonadaceae.  

PubMed

Cauliform bacteria are prosthecate bacteria often specialized for oligotrophic environments. A polyphasic approach, comprising 16S rRNA gene sequencing, lipid analysis and salt tolerance characterizations, was used to clarify the taxonomy of one isolate, strain MCS 33(T), obtained from above the hot water plume of a deep-sea hydrothermal vent near Vancouver island, Canada. Cells contained no detectable phospholipids or sulpholipids, but did contain 1,2-di-O-acyl-3-O-?-D-glucopyranosylglycerol, 1,2-di-O-acyl-3-O-?-D-glucopyranuronosylglycerol and the novel lipid 1,2-di-O-acyl-3-[O-?-D-glucopyranuronosyl]glycerol-6'-N-glycine. It is assumed that the various glucoronosyl lipids are replacing, at least partially, the phospholipids in their various tasks in the cell cycle. The G+C content of the genomic DNA of strain MCS 33(T) was 62.8 mol%, and Q10 was the predominant respiratory ubiquinone. The 16S rRNA gene sequence of this chemoheterotrophic, aerobic, moderately halophilic strain showed only a low similarity of 94.4% to that of Oceanicaulis alexandrii C116-18(T), and both strains also differed based on their lipids. Although the novel strain was isolated from seawater sampled near a hydrothermal vent, its optimum temperature for growth was 30 °C. The main cellular fatty acids were C18:1?7c, C18:0 and the unknown fatty acid ECL 11.798, and the main hydroxy fatty acid was C12:0 3-OH. The strain is proposed to represent a novel species of a new genus, Glycocaulis abyssi gen. nov., sp. nov. The type strain of the type species is MCS 33(T) (=LMG 27140(T)=CCUG 62981(T)). PMID:23148094

Abraham, Wolf-Rainer; Lünsdorf, Heinrich; Vancanneyt, Marc; Smit, John

2012-11-12

328

Autonomous Microbial Sampler (AMS), a device for the uncontaminated collection of multiple microbial samples from submarine hydrothermal vents and other aquatic environments  

NASA Astrophysics Data System (ADS)

An Autonomous Microbial Sampler (AMS) is described that will obtain uncontaminated and exogenous DNA-free microbial samples from most marine, freshwater and hydrothermal ecosystems. Sampling with the AMS may be conducted using manned submersibles, remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), or when tethered to a hydrowire during hydrocast operations on research vessels. The modular device consists of a titanium nozzle for sampling in potentially hot environments (>350 °C) and fluid-handling components for the collection of six independent filtered or unfiltered samples. An onboard microcomputer permits sampling to be controlled by the investigator, by external devices (e.g., AUV computer), or by internal programming. Temperature, volume pumped and other parameters are recorded during sampling. Complete protection of samples from microbial contamination was observed in tests simulating deployment of the AMS in coastal seawater, where the sampling nozzle was exposed to seawater containing 1×10 6 cells ml -1 of a red pigmented tracer organism, Serratia marinorubra. Field testing of the AMS at a hydrothermal vent field was successfully undertaken in 2000. Results of DNA destruction studies have revealed that exposure of samples of the Eukaryote Euglena and the bacterium S. marinorubra to 0.5 N sulfuric acid at 23 °C for 1 h was sufficient to remove polymerase chain reaction (PCR) amplifiable DNA. Studies assessing the suitability of hydrogen peroxide as a sterilizing and DNA-destroying agent showed that 20% or 30% hydrogen peroxide sterilized samples of Serratia in 1 h and destroyed the DNA of Serratia in 3 h, but not 1 or 2 h. DNA AWAY™ killed Serratia and destroyed the DNA of both Serratia and the vent microbe (GB-D) of the genus Pyrococcus in 1 h.

Taylor, Craig D.; Doherty, Kenneth W.; Molyneaux, Stephen J.; Morrison, Archie T.; Billings, John D.; Engstrom, Ivory B.; Pfitsch, Don W.; Honjo, Susumu

2006-05-01

329

A delta13C-based carbon flux model for the hydrothermal vent chemoautotrophic symbiosis Riftia pachyptila predicts sizeable CO(2) gradients at the host-symbiont interface.  

PubMed

The chemoautotrophic symbiosis Riftia pachyptila has extremely 13C-enriched delta13C values. Neither isotopic discrimination by the RubisCO enzyme of their bacterial endosymbionts, nor the delta13C value of CO2 at their hydrothermal vent habitat, suffice to explain biomass delta13C values in this organism, which range from - 9 to - 16 per thousand. However, these 13C-enriched delta13C values are consistent with the presence of 13C-enriched CO2 within the symbiont cytoplasm. Such a 13C-enriched pool of CO2 is expected when the rate of CO2 fixation by RubisCO, which fixes 12CO2 more rapidly than 13CO2, approaches the rate of exchange between intracellular and extracellular CO2 pools. Rapid CO2 fixation rates will also generate concentration gradients between these two pools. In order to estimate the size of these concentration gradients, an equation was derived, which describes the delta13C of tubeworm biomass in terms of the size of the CO2 gradient between the hydrothermal vent environment and the symbiont cytoplasm. Using mass balance equations for CO2 exchange and fixation by the symbionts and the tubeworm host, this model predicts that a CO2 concentration gradient of up to 17-fold between the symbiont cytoplasm and the environment is sufficient to explain even the most 13C-enriched R. pachyptila biomass. This model illustrates how both physical and enzymatic factors can act to influence the delta13C of intracellular CO2, which, in turn, highlights the danger of assigning a carbon fixation pathway to an autotroph based solely on its biomass delta13C value. PMID:12713468

Scott, Kathleen M

2003-05-01

330

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

NASA Astrophysics Data System (ADS)

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.

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

331

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

PubMed Central

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.

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 Lepinay, 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

332

Ocean Vents Were "Factories of Life"  

NSDL National Science Digital Library

This week's In the News focuses on discoveries that provide support for the theory that deep sea hydrothermal vents may have been the "factories of life" three and half billion years ago when Earth's atmosphere did not consist of any oxygen. A recent article published in Science (February 5, 1999, 283:831-833) discusses how scientists at Nagaoka University created an environment similar to a submarine hydrothermal system. Submarine hydrothermals are transition zones where hot water rises from a vent into the cold environment of the surrounding water. The hydrothermal vent sites are termed "black smokers" or sulfide chimneys and are formed when heated water containing metals and volcanic gases rises into the cold deep ocean from hot regions below the seafloor. These scientists added fluid containing the amino acid, glycine, to the simulated environment. They found that glycine polymerizes (one unit is added to the amino acid in a step-wise manner) in the hot region, is released into the cold region where its bonds are solidified, and re-enters the hot region and polymerizes again. The heat from the hot region drives this reaction. The repeated circulation of glycine through the hot and cold water regions of the simulated hydrothermal vents created oligopeptides of glycine. It is suggested that "life probably started with organic chemicals forming into amino acids...from which the first hydrogen-consuming microbes emerged"(3). Researchers at the Carnegie Institution's Geophysical Laboratory suggest that ammonia (NH3) production occurred in early Earth's crust and in hydrothermal vents. Furthermore, organic chemicals such as nitrogen and hydrogen are necessary to form amino acids, which are the basic components of living things. Chris German, of the Southampton Oceanography Centre, spotted a "a hot spring more than 9,000 feet under the Atlantic Ocean where a volcanic vent poured out hydrogen and provided conditions for hydrogen sulfide oxidizing microbes" to survive. Life forms such as giant clams, pale mussels, white crabs, and Pompeii worms (Nature, 1998, 391:545-546) have also been found on these sulfur chimneys. These creatures are dependent on bacteria, which use hydrogen sulfide from vent water as a primary energy source. Scientists hope that studying these ecosystems may shed light on the origin of life on Earth as well as on other worlds in our solar system. The nine resources listed provide background information and insights into these discoveries.

Nannapaneni, Sujani.

1999-01-01

333

Sclerite formation in the hydrothermal-vent “scaly-foot” gastropod—possible control of iron sulfide biomineralization by the animal  

NASA Astrophysics Data System (ADS)

A gastropod from a deep-sea hydrothermal field at the Rodriguez triple junction, Indian Ocean, has scale-shaped structures, called sclerites, mineralized with iron sulfides on its foot. No other organisms are known to produce a skeleton consisting of iron sulfides. To investigate whether iron sulfide mineralization is mediated by the gastropod for the function of the sclerites, we performed a detailed physical and chemical characterization. Nanostructural characterization of the iron sulfide sclerites reveals that the iron sulfide minerals pyrite (FeS 2) and greigite (Fe 3S 4) form with unique crystal habits inside and outside of the organic matrix, respectively. The magnetic properties of the sclerites, which are mostly consistent with those predicted from their nanostructual features, are not optimized for magnetoreception and instead support use of the magnetic minerals as structural elements. The mechanical performance of the sclerites is superior to that of other biominerals used in the vent environment for predation as well as protection from predation. These characteristics, as well as the co-occurrence of brachyuran crabs, support the inference that the mineralization of iron sulfides might be controlled by the gastropod to harden the sclerites for protection from predators. Sulfur and iron isotopic analyses indicate that sulfur and iron in the sclerites originate from hydrothermal fluids rather than from bacterial metabolites, and that iron supply is unlikely to be regulated by the gastropod for iron sulfide mineralization. We propose that the gastropod may control iron sulfide mineralization by modulating the internal concentrations of reduced sulfur compounds.

Suzuki, Yohey; Kopp, Robert E.; Kogure, Toshihiro; Suga, Akinobu; Takai, Ken; Tsuchida, Shinji; Ozaki, Noriaki; Endo, Kazuyoshi; Hashimoto, Jun; Kato, Yasuhiro; Mizota, Chitoshi; Hirata, Takafumi; Chiba, Hitoshi; Nealson, Kenneth H.; Horikoshi, Koki; Kirschvink, Joseph L.

2006-02-01

334

Low-Temperature Hydrothermal Deposits at the 71°N Vent Fields at the Arctic Mid-Ocean Ridge: Architecture, Microtextures, and Geochemistry  

NASA Astrophysics Data System (ADS)

Vast amounts of low-temperature siliceous Fe-deposits are formed distal to a high-temperature hydrothermal venting areas at the southwestern part of the Mohns Ridge. The low-temperature deposits occur as small yellow to rust coloured mounds and chimney-like structures along faults and fissures in the rift valley floor, for distances up to several kilometres. The mounds and chimneys have a stratified structure of millimetres to centimetres thick laminated layers that are alternating with centimetre sized hollow spaces. The individual layers have in general a highly porous microtexture of most frequently branching, twisted filaments resembling stalks of the iron-oxidising Gallionella sp, which have different thickness and colour of the mineral coating in the separate lamina. Other filamentous structures of apparently biogenic as well as abiotic origin are also present, and dominate in some lamina. The deposited material is loosely consolidated due to infilling of the interspaces between the filaments in a number of thin, discrete lamina. The filaments and the interstitial material have a similar composition of mainly FeO and silica, and electron diffraction reveal 2-line ferrihydrite. The REE composition of the siliceous ferrihydrite show a similar pattern to that of the basaltic crust, indicating that they formed from low-temperature hydrothermal fluids, derived from interactions between the basaltic crust and circulating seawater. Mn-accumulation is observed within lamina most commonly at the surface of deposits. Sediment particles of basaltic glass, high- temperature vent minerals like baryte, and diatoms within lamina that are present in discrete layers show that they sequentially formed at the surface of the deposits at the different stages of growth. This together with the architecture of alternating layers of biogenic filaments and hollow spaces suggest that the formation of these deposits were controlled by biofilms of Fe-oxidising microorganisms that developed at the interface between the reduced vent fluid and the surrounding oxidized seawater. Successive nucleation and precipitation of ferrihydrite and amorphous silica on the microbial stalks results in the formation of the mounds and chimneys.

Thorseth, I. H.; Pedersen, R. B.; Kruber, C.; Kosler, J.

2007-12-01

335

Visual Observations and Geologic Settings of the Newly-Discovered Black Smoker Vent Sites Across the Galapagos Ridge-Hotspot Intersection  

Microsoft Academic Search

Nearly one-fifth of the global mid-ocean ridge is hotspot-affected, yet very little is known about how hotspots affect quantity and distribution of high-temperature hydrothermal vents along the ridge. During the 2005-06 GalAPAGoS expedition, acoustic and plume sensor surveys were conducted across the Galapagos ridge- hotspot intersection, lon. 94.5ºW- lon. 89.5ºW, to map fine scale geologic features and locate hydrothermal plumes

P. Anderson; R. Haymon; K. MacDonald; S. White

2006-01-01

336

Novel Chemoautotrophic Endosymbiosis between a Member of the Epsilonproteobacteria and the Hydrothermal-Vent Gastropod Alviniconcha aff. hessleri (Gastropoda: Provannidae) from the Indian Ocean†  

PubMed Central

The hydrothermal-vent gastropod Alviniconcha aff. hessleri from the Kairei hydrothermal field on the Central Indian Ridge houses bacterium-like cells internally in its greatly enlarged gill. A single 16S rRNA gene sequence was obtained from the DNA extract of the gill, and phylogenetic analysis placed the source organism within a lineage of the epsilon subdivision of the Proteobacteria. Fluorescence in situ hybridization analysis with an oligonucleotide probe targeting the specific epsilonproteobacterial subgroup showed the bacterium densely colonizing the gill filaments. Carbon isotopic homogeneity among the gastropod tissue parts, regardless of the abundance of the endosymbiont cells, suggests that the carbon isotopic composition of the endosymbiont biomass is approximately the same as that of the gastropod. Compound-specific carbon isotopic analysis revealed that fatty acids from the gastropod tissues are all 13C enriched relative to the gastropod biomass and that the monounsaturated C16 fatty acid that originates from the endosymbiont is as 13C enriched relative to the gastropod biomass as that of the epsilonproteobacterial cultures grown under chemoautotrophic conditions. This fractionation pattern is most likely due to chemoautotrophy based on the reductive tricarboxylic-acid (rTCA) cycle and subsequent fatty acid biosynthesis from 13C-enriched acetyl coenzyme A. Enzymatic characterization revealed evident activity of several key enzymes of the rTCA cycle, as well as the absence of ribulose-1,5-bisphosphate carboxylase/oxygenase activity in the gill tissue. The results from anatomic, molecular phylogenetic, bulk and compound-specific carbon isotopic, and enzymatic analyses all support the inference that a novel nutritional strategy relying on chemoautotrophy in the epsilonproteobacterial endosymbiont is utilized by the hydrothermal-vent gastropod from the Indian Ocean. The discrepancies between the data of the present study and those of previous ones for Alviniconcha gastropods from the Pacific Ocean imply that at least two lineages of chemoautotrophic bacteria, phylogenetically distinct at the subdivision level, occur as the primary endosymbiont in one host animal type.

Suzuki, Yohey; Sasaki, Takenori; Suzuki, Masae; Nogi, Yuichi; Miwa, Tetsuya; Takai, Ken; Nealson, Kenneth H.; Horikoshi, Koki

2005-01-01

337

Deep Sea Vents Harbor Earth's Hottest Animal  

NSDL National Science Digital Library

This University of Delaware interactive web page combines text, images, video, and audio clips to describe the Pompeii worm (Alvinella pompejana), the most heat tolerant animal on Earth. Features of this site include: a 3-D visual which allows users to manipulate and view the organism from all angles, a video that shows the worm feeding on bacteria in its habitat, and audio clips that enhance images of the worm and its hydrothermal vent community.

2009-07-24

338

Deep Sea Vents Harbor Earth's Hottest Animal  

NSDL National Science Digital Library

This University of Delaware interactive web page combines text, images, video, and audio clips to describe the Pompeii worm (Alvinella pompejana), the most heat tolerant animal on Earth. Features of this site include: a 3-D visual which allows users to manipulate and view the organism from all angles, a video that shows the worm feeding on bacteria in its habitat, and audio clips that enhance images of the worm and its hydrothermal vent community.

Abyss, Mission T.; Studies, University O.

339

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

PubMed Central

A novel hydrothermal field has been discovered at the base of L?ihi 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.

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

340

Geochemical constraints on the modes of carbonate precipitation in peridotites from the Logatchev Hydrothermal Vent Field and Gakkel Ridge  

Microsoft Academic Search

The ultramafic-hosted Logatchev Hydrothermal Field (LHF) at 15°N on the Mid-Atlantic Ridge and the Arctic Gakkel Ridge (GR) feature carbonate precipitates (aragonite, calcite, and dolomite) in voids and fractures within different types of host rocks. We present chemical and Sr isotopic compositions of these different carbonates to examine the conditions that led to their formation. Our data reveal that different

Benjamin Eickmann; Wolfgang Bach; Martin Rosner; Jörn Peckmann

2009-01-01

341

Salinity, pressure and heavy-metal stress response of moderately halophilic bacteria isolated from hydrothermal-vent environments  

Microsoft Academic Search

Moderately halophilic bacteria comprised 0.01-10% of the total microbial community in low-temperature hydrothermal emissions and in the overlying water column. The presence of these microorganisms was initially thought to be linked to brines that are produced by super-critical phase separation beneath deep-sea mid-ocean ridges. While there is conclusive evidence that these brines exist at extremely hot (>400°C) temperatures, it is

J. Z. Kaye; J. A. Baross

2002-01-01

342

Imprint of past environmental regimes on structure and succession of a deep-sea hydrothermal vent community  

Microsoft Academic Search

Dramatic perturbations of ecological communities through rapid shifts in environmental regime do not always result in complete\\u000a mortality of residents. Instead, legacy individuals may remain and influence the succession and composition of subsequent\\u000a communities. We used a reciprocal transplant experiment to investigate whether a legacy effect is detectable in communities\\u000a experiencing an abrupt increase or decrease in hydrothermal fluid flux

Lauren S. Mullineaux; Fiorenza Micheli; Charles H. Peterson; Hunter S. Lenihan; Nilauro Markus

2009-01-01

343

Processes and Rates of Mass Transfer in Ultramafic-Hosted Hydrothermal Systems: An Experimental Study with Implications for Dissolved Inorganic and Organic Components in High-Temperature Vent Fluids  

NASA Astrophysics Data System (ADS)

Recently discovered ultramafic-hosted hydrothermal systems at mid-ocean ridges reveal high temperature vent fluids with relatively high SiO2, Ca, H2, and methane and other hydrocarbons. Dissolved Fe concentrations are the highest of any vent systems yet discovered and require a relatively low pH and reducing conditions in subseafloor reaction zones from which the fluids are derived. This, together with the SiO2 concentrations of the vent fluids, strongly indicates fluid buffering by silica-rich phases possibly produced during pyroxene dissolution, the likely abundant presence of olivine notwithstanding. Theoretical predictions of olivine dissolution kinetics at elevated temperatures and pressures, however, suggest relatively rapid conversion of olivine to talc and serpentine with corresponding lowering of dissolved SiO2 and Fe, and increase in pH. Thus, to test this, we performed a series of experiments at 400°C, 500 bars involving olivine (Fo89) alteration in SiO2-bearing systems containing dissolved Na and chloride concentrations approximately equivalent to the Rainbow hydrothermal system. Time series fluid samples indicate steady state conditions. Results confirm unusually slow olivine reaction kinetics, even when coexisting with moderate to high dissolved SiO2. XPS and SEM analysis indicate Fe-enrichment on olivine surfaces, and formation approximately 14 percent talc. The olivine to talc conversion rate suggests a log rate of olivine hydrolysis of -11.97 (moles/cm2/sec), well below that predicted from available rate data extrapolated from lower temperatures and pressures. The relative enrichment of Fe on olivine surfaces may decrease the thermodynamic and kinetic drive for olivine dissolution; effectively precluding pH increases predicted assuming full equilibrium. Rates and processes of mass transfer involving Fe-bearing minerals may also help to catalyze Fisher-Tropsch synthesis of complex hydrocarbons reported for vent fluids issuing from ultramafic-hosted hydrothermal systems, as suggested by results of a companion series of hydrothermal experiments.

Seyfried, W. E.; Fu, Q.; Foustoukos, D. I.; Allen, D. E.

2004-12-01

344

Global environmental effects of large volcanic eruptions on ocean chemistry: Evidence from ``hydrothermal'' sediments (ODP Leg 185, Site 1149B)  

NASA Astrophysics Data System (ADS)

A Sr-Nd-Pb isotope investigation has been carried out on sediments overlying the Cretaceous oceanic crust at ODP Leg 185 Site 1149B. The sediments (biogenic carbonate and siliceous, clays) contain two horizons with high "excess" concentrations of Fe, Zn, Cu, and Pb. These horizons are both characterized by rare Earth element patterns that are concave-upwards and exhibit both negative Ce and positive Eu anomalies; comparable to those from modern hydrothermal plume particles and sediments. However, Pb isotope signatures differ significantly between the two metal-rich horizons. Metal-rich sediments in the lower part of Unit IV have Pb isotopes that lie on a mixing line between seawater and local oceanic crust end-members, which is consistent with a hydrothermal fall-out originating from a local oceanic spreading centre. In contrast, sediments from the upper part of Unit IV have much more radiogenic Pb isotope ratios, that cannot be related readily to local end-members (off-axis hydrothermal vent, clays, oceanic crust or large igneous provinces (LIP)). Their age-corrected Pb isotope compositions do, however, overlap with basalts from the Parana-Etendeka LIP. Evidence for related environmental effects include a drastic biotic change, higher oceanic ?13C values and more radiogenic seawater 87Sr/86Sr. We estimate that the Parana-Etendeka LIP released ˜1 × 1019 g of carbon into the atmosphere as CO2, corresponding to Pb and S degassing fluxes of ˜1 × 109 g a-1 and ˜15 × 1012 g a-1, respectively. The study demonstrates that Pb isotopes when combined with other geochemical parameters are ideal tools for detecting and tracing LIP volcanism in the marine geological records.

Chavagnac, V.; German, C. R.; Taylor, R. N.

2008-06-01

345

Spontaneous mirror symmetry breaking in the limited enantioselective autocatalysis model: abyssal hydrothermal vents as scenario for the emergence of chirality in prebiotic chemistry.  

PubMed

The emergence of chirality in enantioselective autocatalysis for compounds unable to transform according to the Frank-like reaction network is discussed with respect to the controversial limited enantioselectivity (LES) model composed of coupled enantioselective and non-enantioselective autocatalyses. The LES model cannot lead to spontaneous mirror symmetry breaking (SMSB) either in closed systems with a homogeneous temperature distribution or in closed systems with a stationary non-uniform temperature distribution. However, simulations of chemical kinetics in a two-compartment model demonstrate that SMSB may occur if both autocatalytic reactions are spatially separated at different temperatures in different compartments but coupled under the action of a continuous internal flow. In such conditions, the system can evolve, for certain reaction and system parameters, toward a chiral stationary state; that is, the system is able to reach a bifurcation point leading to SMSB. Numerical simulations in which reasonable chemical parameters have been used suggest that an adequate scenario for such a SMSB would be that of abyssal hydrothermal vents, by virtue of the typical temperature gradients found there and the role of inorganic solids mediating chemical reactions in an enzyme-like role. PMID:23379530

Ribó, Josep M; Crusats, Joaquim; El-Hachemi, Zoubir; Moyano, Albert; Blanco, Celia; Hochberg, David

2013-02-04

346

Lipid composition of deep-sea hydrothermal vent tubeworm Riftia pachyptila, crabs Munidopsis subsquamosa and Bythograea thermydron, mussels Bathymodiolus sp. and limpets Lepetodrilus spp.  

PubMed

Lipid composition was determined for hydrothermal vent species collected by the Deep Submergence Vehicle ALVIN from chimneys at 2,500 m depth on the East Pacific Rise. These are the first lipid biomarker studies for most of these species. Lipid content was low and dominated by polar lipid in the vestimentiferan tubeworm Riftia pachyptila, mussels Bathymodiolus sp. and limpets Lepetodrilus spp. The galatheid (Munidopsis subsquamosa) and most brachyuran adult (Bythograea thermydron) crabs were characterized by higher storage lipid (triacylglycerol). Total polyunsaturated fatty acids were similar in R. pachyptila plume and body, but higher in the posterior part of the soft body, which had more docosahexaenoic acid (2-5% of total FA) compared to the anterior and plume (< or =0.3%). Two sulphur-oxidizing bacterial markers, 16:1(n-7)c and 18:1(n-7)c, were high in R. pachyptila and mussel (up to 23%), but lower in both crab species (4-17%). R. pachyptila had greater nonmethylene interrupted diunsaturated fatty acids (8-13%) than all other species (2-8%). R. pachyptila may desaturate and elongate 18:1(n-7)c to obtain essential polyunsaturated fatty acids 20:5(n-3) and 20:4(n-6). The sterol composition of R. pachyptila included similar amounts of cholesterol and desmosterol, whereas the other species had a more diverse sterol composition. These differences in lipids, fatty acids and sterols reflect diverse nutritional strategies and possibly temperature regimes in these species. PMID:15893489

Phleger, Charles F; Nelson, Matthew M; Groce, Ami K; Cary, S Craig; Coyne, Kathryn J; Nichols, Peter D

2005-06-01

347

Molecular Systematics of the Deep-Sea Hydrothermal Vent Endemic Brachyuran Family Bythograeidae: A Comparison of Three Bayesian Species Tree Methods  

PubMed Central

Brachyuran crabs of the family Bythograeidae are endemic to deep-sea hydrothermal vents and represent one of the most successful groups of macroinvertebrates that have colonized this extreme environment. Occurring worldwide, the family includes six genera (Allograea, Austinograea, Bythograea, Cyanagraea, Gandalfus, and Segonzacia) and fourteen formally described species. To investigate their evolutionary relationships, we conducted Maximum Likelihood and Bayesian molecular phylogenetic analyses, based on DNA sequences from fragments of three mitochondrial genes (16S rDNA, Cytochrome oxidase I, and Cytochrome b) and three nuclear genes (28S rDNA, the sodium–potassium ATPase a-subunit ‘NaK’, and Histone H3A). We employed traditional concatenated (i.e., supermatrix) phylogenetic methods, as well as three recently developed Bayesian multilocus methods aimed at inferring species trees from potentially discordant gene trees. We found strong support for two main clades within Bythograeidae: one comprising the members of the genus Bythograea; and the other comprising the remaining genera. Relationships within each of these two clades were partially resolved. We compare our results with an earlier hypothesis on the phylogenetic relationships among bythograeid genera based on morphology. We also discuss the biogeography of the family in the light of our results. Our species tree analyses reveal differences in how each of the three methods weighs conflicting phylogenetic signal from different gene partitions and how limits on the number of outgroup taxa may affect the results.

Santamaria, Carlos A.; Leignel, Vincent; Guinot, Daniele

2012-01-01

348

Thermotomaculum hydrothermale gen. nov., sp. nov., a novel heterotrophic thermophile within the phylum Acidobacteria from a deep-sea hydrothermal vent chimney in the Southern Okinawa Trough.  

PubMed

A novel heterotrophic, thermophilic bacterium, designated strain AC55(T), was isolated from a deep-sea hydrothermal vent chimney at the Hatoma Knoll in the Okinawa Trough, Japan. Cells of strain AC55(T) were non-motile, long rods (2.0- to 6.8-?m long and 0.3- to 0.6-?m wide). The strain was an obligatory anaerobic heterotroph capable of fermentative growth on complex proteinaceous substances. Elemental sulfur was reduced to hydrogen sulfide but did not stimulate growth. Growth was observed between 37 and 60°C (optimum 55°C), pH 5.5 and 8.5 (optimum pH 6.6), and in the presence of 1.5-4.5% (w/v) NaCl (optimum 2.5%, w/v). Menaquinone-7 and -8 were the major respiratory quinones. The G + C content of the genomic DNA from strain AC55(T) was 51.6 mol%. The 16S rRNA gene sequence analysis revealed that strain AC55(T) was the first cultivated representative of Acidobacteria subdivision 10. Based on the physiological and phylogenetic features of the novel isolate, the genus name Thermotomaculum gen. nov. is proposed, with Thermotomaculum hydrothermale sp. nov. as the type species. The type strain is AC55(T) (=JCM 17643(T) = DSM 24660(T) = NBRC 107904(T)). PMID:22212657

Izumi, Hiroshi; Nunoura, Takuro; Miyazaki, Masayuki; Mino, Sayaka; Toki, Tomohiro; Takai, Ken; Sako, Yoshihiko; Sawabe, Tomoo; Nakagawa, Satoshi

2012-01-03

349

Deferribacter desulfuricans sp. nov., a novel sulfur-, nitrate- and arsenate-reducing thermophile isolated from a deep-sea hydrothermal vent.  

PubMed

A novel anaerobic, heterotrophic thermophile was isolated from a deep-sea hydrothermal vent chimney at the Suiyo Seamount in the Izu-Bonin Arc, Japan. The cells were bent, flexible rods, with a single polar flagellum. Growth was observed between 40 and 70 degrees C (optimum temperature: 60-65 degrees C; doubling time, 40 min) and between pH 5.0 and 7.5(optimum pH 6.5). The isolate was a strictly anaerobic heterotroph capable of using complex organic compounds (yeast extract, tryptone, peptone, casein and Casamino acids), ethanol and various organic acids as energy and carbon sources. Hydrogen could serve as a supplementary energy source. Elemental sulfur (S(0)), nitrate or arsenate was required for growth as an electron acceptor. The G + C content of the genomic DNA was 38.6 mol%. Phylogenetic analysis based on 16S rDNA sequences indicated that isolate SSM1(T) is closely related to Deferribacter thermophilus BMA(T) (98.1%). However, the novel isolate could be clearly differentiated from D. thermophilus BMA(T) on the basis of its physiological and genetic properties. The name Deferribacter desulfuricans sp. nov. (type strain SSM1(T) = JCM 11476(T) = DSM 14783(T)) is proposed. PMID:12807210

Takai, Ken; Kobayashi, Hideki; Nealson, Kenneth H; Horikoshi, Koki

2003-05-01

350

(210)Po and (210)Pb in the tissues of the deep-sea hydrothermal vent mussel Bathymodiolus azoricus from the Menez Gwen field (Mid-Atlantic Ridge).  

PubMed

The hydrothermal deep-sea vent fauna is naturally exposed to a highly specific environment enriched in potentially toxic species such as sulfides, metals and natural radionuclides due to the convective seawater circulation inside the oceanic crust and its interaction with basaltic or ultramafic host rocks. However, data on radionuclides in biota from such environment are very limited. An investigation was carried out on tissue partitioning of (210)Po and (210)Pb, two natural radionuclides within the (238)U decay chain, in Bathymodiolus azoricus specimens from the Mid-Atlantic Ridge (Menez Gwen field). These two elements showed different distributions with high (210)Pb levels in gills and high (210)Po levels in both gills and especially in the remaining parts of the body tissue (including the digestive gland). Various factors that may explain such partitioning are discussed. However, (210)Po levels encountered in B. azoricus were not exceptionally high, leading to weighted internal dose rate in the range 3 to 4 ?Gy h?¹. These levels are slightly higher than levels characterizing coastal mussels (~1 ?Gy h?¹). PMID:21126753

Charmasson, Sabine; Le Faouder, Antoine; Loyen, Jeanne; Cosson, Richard P; Sarradin, Pierre-Marie

2010-12-03

351

Methanothermococcus okinawensis sp. nov., a thermophilic, methane-producing archaeon isolated from a Western Pacific deep-sea hydrothermal vent system.  

PubMed

A novel thermophilic, methane-producing archaeon was isolated from a deep-sea hydrothermal vent chimney at the Iheya Ridge, in the Okinawa Trough, Japan. The cells were highly motile, irregular cocci, with a polar bundle of flagella. Growth was observed between 40 and 75 degrees C (optimum 60-65 degrees C; 30 min doubling time) and between pH 4.5 and 8.5 (optimum pH 6.7). The isolate was a strictly anaerobic autotroph capable of using hydrogen and carbon dioxide as sole sources of energy and carbon. Formate can serve as an alternative energy source. The G+C content of the genomic DNA was 33.5 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA-DNA hybridization analysis indicated that the isolate was closely related to members of the genera Methanococcus and Methanothermococcus. This isolate, however, could be differentiated from the previously described species of these genera on the basis of its physiological and molecular properties. The name Methanothermococcus okinawensis sp. nov is proposed, with the type strain IH1T (=JCM 11175T=DSM 14208T). PMID:12148612

Takai, Ken; Inoue, Akira; Horikoshi, Koki

2002-07-01

352

Comparative assessment of five potential sites for hydrothermal magma systems: geochemistry  

SciTech Connect

A brief discussion is given of the geochemical objectives and questions that must be addressed in such an evaluation. A summary of the currently published literature that is pertinent in answering these questions is presented for each of the five areas: The Geysers-Clear Lake region, Long Valley, Rio Grand Rift, Roosevelt Hot Springs, and the Salton Trough. The major geochemical processes associated with proposed hydrothermal sites are categorized into three groups for presentation: geochemistry of magma and associated volcanic rocks, geochemistry of hydrothermal solutions, and geochemistry of hydrothermal alteration. (MHR)

White, A.F.

1980-08-01

353

Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-sea hydrothermal vent that resists ionizing radiation.  

PubMed

Enrichments for anaerobic organotrophic hyperthermophiles were performed with hydrothermal chimney samples collected at the Guaymas Basin (27 degrees 01' N, 111 degrees 24' W). Positive enrichments were submitted to gamma-irradiation at a dose of 30 kGy. One of the resistant strains, designated strain EJ3(T), formed regular motile cocci. The new strain grew between 55 and 95 degrees C, with an optimum growth temperature of 88 degrees C. The optimal pH for growth was 6.0, and the optimum NaCl concentration for growth was around 20 g l(-1). Strain EJ3(T) was an obligately anaerobic heterotroph that utilized yeast extract, tryptone and peptone. Elemental sulfur or cystine was required for growth and reduced to hydrogen sulfide. The G + C content of the genomic DNA was 51.3 mol%. As determined by 16S rRNA gene sequence analysis, the organism was most closely related to Thermococcus celer, Thermococcus guaymasensis, Thermococcus hydrothermalis, Thermococcus profundus and Thermococcus gorgonarius. However, no significant homology was observed between them by DNA-DNA hybridization. The novel organism also possessed phenotypic traits that differ from those of its closest phylogenetic relatives. Therefore, it is proposed that this isolate, which constitutes the most radioresistant hyperthermophilic archaeon known to date, should be described as the type strain of a novel species, Thermococcus gammatolerans sp. nov. The type strain is EJ3(T) (= DSM 15229(T) = JCM 11827(T)). PMID:12807211

Jolivet, Edmond; L'Haridon, Stéphane; Corre, Erwan; Forterre, Patrick; Prieur, Daniel

2003-05-01

354

Iron Moessbauer spectroscopy: Superparamagnetism in hydrothermal vents and the search for evidence of past life on Mars  

NASA Astrophysics Data System (ADS)

In view of the demonstrated value of Iron Moessbauer Spectroscopy (FeMS) in the study of extraterrestrial iron and the fact that, after silicon and oxygen, iron is the most abundant element on the surface of Mars, we proposed, and have under development, a backscatter Moessbauer spectrometer with x ray fluorescence capability (BaMS/XRF) for use on Mars as a geophysical prospecting instrument. Specifically, we have proposed BaMS/XRF as part of the geochemistry instrumentation on NASA's Mars Environment Survey (MESUR) mission. BaMS/XRF will have applications in: (1) the study of past environments through the examination of sedimentary material; (2) the study of the contemporary Martian environment; and (3) the study of iron-containing minerals of possible biogenic origin. Development of a reference library from a geophysical point of view for putative Martian surface materials at appropriate temperatures is now underway. We carried out preliminary optical reflectance and FeMS measurements on mineral products (iron oxyhydroxides) of deep-sea hydrothermal activity. Various aspects of this investigation are presented.

Agresti, David G.; Wdowiak, Thomas J.

1992-12-01

355