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| Registros recuperados: 39 | |
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| Khripounoff, Alexis; Caprais, Jean-claude; Decker, Carole; Essirard, Mikael; Le Bruchec, Julie; Noel, Philippe; Olu, Karine. |
| We have studied two species of vesicomyid bivalves inhabiting different areas of sulfide-rich sediments in association with methane seepage at two pockmarks located at about 650 m and 3150 m depth, respectively, along the Gabon-Congo margin, and organic-rich sediments in the deepest zone (4950 m depth) of the Congo deep-sea fan. Benthic chambers Calmar were deployed on three study sites to assess gas and solute exchanges at the water-sediment interface. We recorded in situ measurements of oxygen, total carbon dioxide, ammonium, methane, and sulfide in two clam beds at each site. At all sites, irrespective of which the vesicomyid species are present, oxygen consumption was high and variable (28–433 mmol m−2 d−1) as was total carbon dioxide emission (36–1857... |
| Tipo: Text |
Palavras-chave: Benthic chamber; Cold-seep ecosystem; Reduced sediment; Gas fluxes; Vesicomyid bivalves; Gulf of Guinea. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00226/33746/32160.pdf |
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| Khripounoff, Alexis; Vangriesheim, Annick; Crassous, Philippe; Segonzac, Michel; Colaco, Ana; Desbruyeres, Daniel; Barthelemy, Roxane. |
| In order to provide information about the export and the distribution of hydrothermal particulate material to the surrounding deep ocean, four moorings were deployed in the vicinity of the hydrothermal Rainbow vent field (Mid-Atlantic Ridge, 36 degrees 14'N, 2250 m depth). The first mooring was a sediment trap with a current meter deployed at 2 m from a chimney of the Rainbow vent field and 1.5 m above the bottom (a.b.) for 16 days. It represented the reference for the initial composition of particles produced by the vent. The total mean mass particle flux (6.9 g m(-2) d(-1)) was distinctly higher than the flux measured at the shallower hydrothermal vents on the MAR segment. This particulate flux showed a high temporal variation at the scale of a few days... |
| Tipo: Text |
Palavras-chave: Zooplankton; Biochemistry; Geochemistry; Particle flux; Hydrothermal vent. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/2001/publication-801.pdf |
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| Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie Laure. |
| We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n=25), estuaries (n=18), open-ocean settings (n=15), and cold seeps (n=12). Sedimentary Organic Matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2 – 0.02M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H202 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2... |
| Tipo: Text |
Palavras-chave: Organic matter; Rare earth elements; REE; Neodymium isotopes; ΕNd; Sediment; Boundary Exchange; Paleoceanography. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00191/30250/28682.pdf |
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| Rabouille, C.; Dennielou, Bernard; Baudin, F.; Raimonet, M.; Droz, Laurence; Khripounoff, Alexis; Martinez, P.; Mejanelle, L.; Michalopoulos, P.; Pastor, Lucie; Pruski, A.; Ragueneau, Olivier; Reyss, J.-l.; Ruffine, Livio; Schnyder, J.; Stetten, E.; Taillefert, M.; Tourolle, Julie; Olu, Karine. |
| Carbon and silicon cycles at the Earth surface are linked to long-term variations of atmospheric CO2 and oceanic primary production. In these cycles, the river-sea interface is considered a biogeochemical hotspot, and deltas presently receive and preserve a major fraction of riverine particles in shallow water sediments. In contrast, periods of glacial maximum lowstand were characterized by massive exports of sediments to the deep-sea via submarine canyons and accumulation in deep-sea fans. Here, we calculate present-day mass balances for organic carbon (OC) and amorphous silica (aSi) in the terminal lobe complex of the Congo River deep-sea fan as an analogue for glacial periods. We show that this lobe complex constitutes a megasink with the current... |
| Tipo: Text |
Palavras-chave: Present; Paleoceanography; South Atlantic; Inorganic geochemistry; Organic geochemistry; Sedimentology-marine cores. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00511/62289/66720.pdf |
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| Olu, Karine; Decker, Carole; Pastor, Lucie; Caprais, Jean-claude; Khripounoff, Alexis; Morineaux, Marie; Ain Baziz, M.; Menot, Lenaick; Rabouille, C.. |
| Methane-rich fluids arising from organic matter diagenesis in deep sediment layers sustain chemosynthesis-based ecosystems along continental margins. This type of cold seep develops on pockmarks along the Congo margin, where fluids migrate from deep-buried paleo-channels of the Congo River, acting as reservoirs. Similar ecosystems based on shallow methane production occur in the terminal lobes of the present-day Congo deep-sea fan, which is supplied by huge quantities of primarily terrestrial material carried by turbiditic currents along the 800 km channel, and deposited at depths of up to nearly 5000 m. In this paper, we explore the effect of this carbon enrichment of deep-sea sediments on benthic macrofauna, along the prograding lobes fed by the current... |
| Tipo: Text |
Palavras-chave: Chemosynthesis-based ecosystems; Cold seeps; Organic rich sediments; Macrofaunal communities. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00384/49561/50053.pdf |
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| Khripounoff, Alexis; Sibuet, Myriam. |
| In deep waters, deposit-feeding holothurians represent a high percentage of the total abyssal biomass and play an important ecological role in sediment modification. The feeding of these organisms, which inhabit a nutritively poor environment, has been studied by means of analyses of intestinal contents. Four abundant species : Psychropotes longicauda Theel, Paroriza pallens (Koehler), Benthogone rosea Koehler and Molpadia blakei (Theel), collected between 2000 and 4500 m in the Bay of Biscay during three cruises organized by CNEXO-COB, were chosen for this study. The morphological characteristics of the ingested alimentary particles are described and the results of analyses of the organic matter in the guts reported. The species studied do not exhibit a... |
| Tipo: Text |
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| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/publication-5309.pdf |
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| Olu, Karine; Caprais, Jean-claude; Galeron, Joelle; Causse, R.; Von Cosel, R.; Budzinski, H.; Le Menach, K.; Le Roux, C.; Levache, D.; Khripounoff, Alexis; Sibuet, Myriam. |
| Detailed surveying with an ROV found that a dense and diverse cold-seep community colonises a giant pockmark located at 3200 m depth, 8 km north from the deep Congo channel. Several types of assemblages, either dominated by Mytilidae and Vesicomyidae bivalves or Siboglinidae polychaetes, are distributed on the 800-m diameter active area. The site is characterised by a most active central zone in a depression with abundant carbonate concretions and high methane fluxes where high-density clusters of mussels and siboglinids dominate. In contrast, the peripheral zones display large fields of dead and live vesicomyids on soft sediment, with a lower mean density and lower methane concentration in seawater. The associated megafauna includes Alvinocarididae... |
| Tipo: Text |
Palavras-chave: Congo Angola margin; Atlantic Equatorial African margin; Vagrant species; Isotopic signature; Megafauna; Cold seep. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7478.pdf |
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| Tengberg, A; Hovdenes, J; Andersson, H; Brocandel, O; Diaz, R; Hebert, D; Arnerich, T; Huber, C; Kortzinger, A; Khripounoff, Alexis; Rey, F; Ronning, C; Schimanski, J; Sommer, S; Stangelmayer, A. |
| In this article, we evaluate the performance of a commercially available lifetime-based optode and compare it with data obtained by other methods. We performed a set of 10 different tests, including targeted laboratory evaluations and field studies, covering a wide range of situations from shallow coastal waters and wastewater treatment plants to abyssal depths. Our principal conclusion is that, owing to high accuracy (+/- 2 mu M), long-term stability (more than 20 months), lack of pressure hysteresis, and limited cross-sensitivity, this method is overall more suitable for oxygen monitoring than other methods. |
| Tipo: Text |
Palavras-chave: Lifetime based optode; Measure; Oxygen; Aquatic systems. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1413.pdf |
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| Crassous, Philippe; Khripounoff, Alexis. |
| Nine sediment traps were assembled in triplicate on a frame and deployed at 100 m above the bottom in the California abyssal plain (4 100 m depth) for ten days. The distances between traps were from 30 cm to 11 km. The main flux measured during this period was 167 mg m(-2) day(-1) with a minimum of 43 mg m(-2) d(-1) and a maximum of 283 mg m(-2) d(-1). This high variation of the particulate flux at the kilometric scale was also observed at a metric scale: for example, the particulate flux measured with one of triplicate traps was equal to 82.3 +/- 46.5 mg m(-2) d(-1) (more than 50 % of variation) between traps distant of less than 1 m. To explain this heterogeneity of the flux measurement, some hypotheses are developed in this study: sampling artefact,... |
| Tipo: Text |
Palavras-chave: SEDIMENT TRAPS; DEEP SEA; HORIZONTAL FLUX VARIATION. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00098/20885/18499.pdf |
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| Stabholz, M.; Durrieu De Madron, X.; Canals, M.; Khripounoff, Alexis; Taupier-letage, Isabelle; Testor, Pierre; Heussner, S.; Kerherve, P.; Delsaut, N.; Houpert, Loic; Lastras, G.; Dennielou, Bernard. |
| The deep outer margin of the Gulf of Lions and the adjacent basin, in the western Mediterranean Sea, are regularly impacted by open-ocean convection, a major hydrodynamic event responsible for the ventilation of the deep water in the western Mediterranean Basin. However, the impact of open-ocean convection on the flux and transport of particulate matter remains poorly understood. The variability of water mass properties (i.e., temperature and salinity), currents, and particle fluxes were monitored between September 2007 and April 2009 at five instrumented mooring lines deployed between 2050 and 2350-m depth in the deepest continental margin and adjacent basin. Four of the lines followed a NW-SE transect, while the fifth one was located on a sediment wave... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00125/23654/21571.pdf |
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| Menot, Lenaick; Crassous, Philippe; Desbruyeres, Daniel; Galeron, Joelle; Khripounoff, Alexis; Sibuet, M.. |
| In the framework of the deep-sea environmental programme BIOZAIRE (Ifremer-Total), colonization trays were deployed for 283-433 days at three sites along the equatorial West African margin: ZA at 1300-m depth, ZC at 4000-m depth far from the Congo canyon and ZD at 4000-m depth close to the Congo canyon. The experiments aimed at determining the influence of depth and local environmental settings on macrofaunal colonization patterns and organic carbon degradation rates. The trays were filled with glass beads and this artificial substrate was enriched with ground particulate organic matter in a gradient of 0%, 0.34%, 1.02% and 3.43% organic carbon. The highest rates of organic carbon degradation ranged, according to the duration of the experiments, from 1.59... |
| Tipo: Text |
Palavras-chave: Diversity; Organic enrichment; Macrofauna; Deep sea; Colonization; Biozaire. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7323.pdf |
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| Riou, Virginie; Colaco, Ana; Bouillon, Steven; Khripounoff, Alexis; Dando, Paul; Mangion, Perrine; Chevalier, Emilie; Korntheuer, Michael; Santos, Raphael; Dehairs, Frank. |
| Bathymodiolus azoricus mussels thrive 840 to 2300 m deep at hydrothermal vents of the Azores Triple Junction on the Mid-Atlantic Ridge. Although previous studies have suggested a mixotrophic regime for this species, no analysis has yet yielded direct evidence for the assimilation of particulate material. In the present study, tracer experiments in aquaria with C-13- and N-15-labelled amino acids and marine cyanobacteria demonstrate for the first time the incorporation of dissolved and particulate organic matter in soft tissues of vent mussel. The observation of phytoplanktonic tests in wild mussel stomachs highlights the occurrence of in situ ingestion of sea-surface-derived material. Particulate organic carbon fluxes in sediment traps moored away from... |
| Tipo: Text |
Palavras-chave: Bathymodiolus azoricus; Particulate and dissolved material; Nitrogen and carbon assimilation; Deep sea; Hydrothermal vent; Mussel. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00005/11589/8230.pdf |
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| Khripounoff, Alexis; Caprais, Jean-claude; Decker, Carole; Le Bruchec, J.; Noel, Philippe; Husson, Berengere. |
| We studied bivalves (vesicomyids and mytilids) inhabiting four different areas of high sulfide and methane production: 1) in the Gulf of Guinea, two pockmarks (650 m and 3150 m depth) and one site rich in organic sediments in the deepest zone (4950 m average depth), 2) at the Azores Triple Junction on the Mid-Atlantic Ridge, one hydrothermal site (Lucky Strike vent field, 1700 m depth). Two types of Calmar benthic chambers were deployed, either directly set into the sediment (standard Calmar chamber) or fitted with a tank to isolate organisms from the sediment (modified Calmar chamber), to assess gas and solute exchanges in relation to bivalve bed metabolism. Fluxes of oxygen, total carbon dioxide, ammonium and methane were measured. At the site with... |
| Tipo: Text |
Palavras-chave: Deep-sea; Benthic chamber; Vesicomyid and Mytilid bivalves; Respiration rate; Cold seep; Hydrothermal vent. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00341/45204/44614.pdf |
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| Mejanelle, Laurence; Riviere, Beatrice; Pinturier, Laurence; Khripounoff, Alexis; Baudin, Francois; Dachs, Jordi. |
| Hydrocarbons were analyzed in sediments from the Congo River deep-sea fan, from the Congo River, and in sinking particles collected by sediment traps 40 m above the sediment. Studied sites encompassed three lobes of decreasing age of formation along the canyon: sites A, F and C and a another lobe system, disconnected from the active channel since 4 ka, Site E. Terrestrial long-chain odd n-alkanes were dominant in all sediments of the lobe system. Unsaturated terpenoids sourced by higher plants, such as gammacerene, lupene, ursene and oleanene, were also detected. At site C, characterized by high accumulation rates (10–20 cm yr−1), the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations (10 to 17 μg... |
| Tipo: Text |
Palavras-chave: Congo fan; Hydrocarbons; NAH; Hopanes; Hopenes; Sediments; Turbidite system. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00388/49902/50472.pdf |
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| Tengberg, Anders; Hall, P; Andersson, U; Linden, B; Styrenius, O; Boland, G; De Bovee, F; Carlsson, B; Ceradini, S; Devol, A; Duineveld, G; Friemann, J; Glud, R; Khripounoff, Alexis; Leather, J; Linke, P; Lund Hansen, L; Rowe, G; Santschi, P; De Wilde, P; Witte, U. |
| We have compared 14 different sediment incubation chambers, most of them were used on bottom landers. Measurements of mixing time, pressure gradients at the bottom and Diffusive Boundary Layer thickness (DBL) were used to describe the hydrodynamic properties of the chambers and sediment-water solute fluxes of silicate (34 replicates) and oxygen (23 replicates) during three subsequently repeated incubation experiments on a homogenized, macrofauna-free sediment. The silicate fluxes ranged from 0.24 to 1.01 mmol m(-2) day(-1) and the oxygen fluxes from 9.3 to 22.6 mmol m(-2) day(-1). There was no statistically significant correlation between measured fluxes and the chamber design or between measured fluxes and hydrodynamic settings suggesting that type of... |
| Tipo: Text |
Palavras-chave: Comparative flux incubations; Hydrodynamic properties; Calibration; Benthic chambers. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-750.pdf |
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| Galeron, Joelle; Menot, Lenaick; Renaud, Nolwenn; Crassous, Philippe; Khripounoff, Alexis; Treignier, C.; Sibuet, M.. |
| Density, taxonomic composition at higher taxon level and vertical distribution of benthic macrofaunal communities and sediment characteristics (pore water, nitrogen, organic carbon, sulfur, C/N ratio, n-alcohol biomarkers) were examined at three deep sites on the Congo-Gabon continental margin. This study was part of the multidisciplinary BIOZAIRE project that aimed at studying the deep benthic ecosystems in the Gulf of Guinea. Sampling of macrofaunal communities and of sediment was conducted during three cruises (January 2001, December 2001 and December 2003) at two downslope sites (4000 m depth), one located near the Congo submarine channel (15 km in the south) and the other one far from the channel (150km in the South). The third area located 8 km north... |
| Tipo: Text |
Palavras-chave: Deep sea; Distribution; Community structure; Macrofauna; Congo canyon; Congo Angola margin; Equatorial west Africa margin; Atlantic. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7315.pdf |
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| Khripounoff, Alexis; Vangriesheim, Annick; Crassous, Philippe; Segonzac, Michel; Lafon, V; Waren, A. |
| In order to provide information on the production and the distribution of hydrothermal particulate and biological material produced by deep-sea hydrothermal vents, three moorings with sediment traps and currentmeters were deployed for one year in the Azores Triple Junction region. Two moorings were positioned close to two hydrothermal vent fields at the Mid-Atlantic Ridge (Rainbow, 36 degrees 14'N, 33 degrees 54'W, 2250 in depth and Lucky Strike 37 degrees 17'N, 32 degrees 17'W, 1600 in depth). A third was moored out of the influence of the Rainbow vents representing the reference of the pelagic flux in this area. At the Rainbow field, particulate flux (range 341-634 g m(-2)d(-1)) showed a high temporal variation controlled essentially by the current... |
| Tipo: Text |
Palavras-chave: Bivalve reproduction; Bivalve larvae; Particle composition; Particle flux; Currents; Deep sea hydrothermal vents. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4059.pdf |
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| Registros recuperados: 39 | |
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