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| Registros recuperados: 23 | |
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| Ragueneau, O.; Regaudie-de-gioux, A.; Moriceau, B.; Gallinari, M.; Vangriesheim, Annick; Baurand, F.; Khripounoff, Alexis. |
| To elucidate the origin of the silicic acid (DSi) anomaly observed along the 4000 isobath on the Congo margin, we have established a benthic Si mass balance and performed direct measurements of biogenic silica (bSiO(2)) dissolution in the deep waters and in the sediments. Results strongly suggest that the anomaly originates from the sediments; the intensity of DSi recycling is consistent with the degradation of organic matter, as observed from Si:O-2 ratios in the benthic fluxes compared to that ratio observed in the anomalies. Strong imbalances, observed in both the Si and C mass balances, suggest that the biogenic matter that degrades and dissolves in these sediments near 4000 m does not come from pelagic sedimentation. It is probably not coming also... |
| Tipo: Text |
Palavras-chave: Congo; Continental margin; Preservation; Dissolution; Biogenic silica. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7410.pdf |
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| Lo Bue, N.; Vangriesheim, Annick; Khripounoff, Alexis; Soltwedel, T.. |
| Four sets of measurements performed between 2005 and 2010 in the deep central Atlantic, the deep north-western Mediterranean Sea, and in the Arctic Ocean revealed strange anomalies in the performance of the Aanderaa optode 3830 sensors mounted on RCMI I current meters in low current regimes (current speeds > 10 cm s(-1)). All oxygen datasets collected during these deployments showed significant drops of oxygen (50-100 mu mol) affecting the data stability of the optode sensors in low hydrodynamic conditions. High correlations between all acquired parameters (temperature, turbidity, speed and direction of currents) verified that no unusual event occurred in the mooring areas during the periods of acquisition, although natural events responsible for such... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00045/15584/14489.pdf |
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| Vangriesheim, Annick; Treguier, Anne-marie; Andre, Gael. |
| Current meter measurements have been carried out for 3 years on the continental slope of the Gulf of Guinea, near 7.5 degrees S off the Angola coast. Currents in a water depth of 1300 m over the continental slope show a remarkable biweekly oscillation, bottom intensified, and with currents oriented nearly parallel to the isobaths. With a peak-to-peak amplitude reaching 20-30 cm s(-1) at 30 in above the bottom, this signal is the most energetic at sub-inertial frequencies. Simultaneous measurements deeper on the continental rise (in a water depth of 4000 m) show a more complex signal dominated by lower frequencies, and with less clear polarization. Simple linear topographic wave theories are compared to the observations. A combination of coastal trapped... |
| Tipo: Text |
Palavras-chave: Linear wave model; Current meter measurement; Current oscillation; Continental slope. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1032.pdf |
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| Guiavarc'H, Catherine; Treguier, Anne-marie; Vangriesheim, Annick. |
| In the Gulf of Guinea, intraseasonal variability is large at the equator and along the coast. Current data on the continental slope near 7.5° S show very energetic biweekly oscillations at 1300 m depth. A high resolution primitive equation numerical model demonstrates that this deep variability is forced by equatorial winds, through the generation of equatorial Yanai waves that propagate eastward and at depth, and then poleward as coastally-trapped waves upon reaching the coast of Africa. Intraseasonal variability is intensified along the coast of the Gulf of Guinea, especially in the 1020 day period range and at depths between 500 and 1500 m. The kinetic energy distribution is well explained at first order by linear theory. Along the equator, eastward... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6739.pdf |
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| Sibuet, Myriam; Vangriesheim, Annick. |
| The long-term BIOZAIRE multidisciplinary deep-sea environmental program on the West Equatorial African margin organized in partnership between Ifremer and TOTAL aimed at characterizing the benthic community structure in relation with physical and chemical processes in a region of oil and gas interest. The morphology of the deep Congo submarine channel and the sedimentological structures of the deep-sea fan were established during the geological ZAIANGO project and helped to select study sites ranging from 350 to 4800 m water depth inside or near the channel and away from its influence. Ifremer conducted eight deep-sea cruises on board research vessels between 2000 and 2005. Standardized methods of sampling together with new technologies such as the ROV... |
| Tipo: Text |
Palavras-chave: Cold coral; Cold seep communities; Benthos diversity; Turbidity current; Congo canyon; Gulf of Guinea. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7349.pdf |
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| Vangriesheim, Annick. |
| Ce document est une présentation des mesures courantométriques et hydrologiques recueillies au cours des campagnes EDYlOC 81 et 82. L'objectif était l'étude des courants et de leur variabilité spatiale et temporelle dans la couche de fond associée à l'étude de la structure hydrologique dans la même zone. Dans ce but, un réseau de six mouillages portant chacun deux courantomètres a été mouillé en mai 1981 au voisinage du point 47°N, 14°30°W; ceux-ci ont été relevés en avril 1982. Lors de cette seconde campagne, des mesures de néphélométrie ont été effectuées au cours de profils bathysonde. |
| Tipo: Text |
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| Ano: 1986 |
URL: https://archimer.ifremer.fr/doc/00419/53068/54007.pdf |
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| Veillette, J; Sarrazin, Jozee; Gooday, A; Galeron, Joelle; Caprais, Jean-claude; Vangriesheim, Annick; Etoubleau, Joel; Christian, J; Juniper, S. |
| The poorly known ferromanganese nodule fauna is a widespread hard substratum community in the deep sea that will be considerably impacted by large-scale nodule mining operations. The objective of this study was to analyze the spatial distribution of the fauna attached to nodules in the Clarion-Clipperton Fracture Zone at two scales; a regional scale that includes the east (14 degrees N, 130 degrees W) and the west (9 degrees N, 150 degrees W) zones and a local scale in which different geological facies (A, B, C and west) are recognizable. The fauna associated with 235 nodules was quantitatively described: 104 nodules from the east zone (15 of facies A, 50 of facies B and 39 of facies C) and 131 nodules from the west zone. Percent cover was used to quantify... |
| Tipo: Text |
Palavras-chave: Environmental impacts; Environmental factors; Geographical distribution; Agglutinated foraminifera; Fixed fauna; Ferromanganese nodules. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3537.pdf |
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| Vangriesheim, Annick; Bournot-marec, Claudie; Fontan, Anne-claire. |
| During the JGOFS-France/Eumeli programme, biogeochemical processes governing particle fluxes throughout the water column were studied in the Eastern Subtropical North Atlantic Ocean. From February 1991 to December 1992, three consecutive sets of sediment trap moorings were installed at two sites: the mesotrophic site: similar to18degrees 30 N, 21degrees 00 W, and the oligotrophic site: similar to21degrees 00 N, 31degrees 00 W. Currents were measured at each sediment trap level (250, 1000 and 2500 m) in order to understand better the dynamics in this area and its influence on the particle fluxes through the water column and to monitor the current speed conditions during the particle trapping. The results of these current measurements are presented here,... |
| Tipo: Text |
Palavras-chave: Rossby waves; Current variability; Cape Verde frontal zone; Eastern subtropical; North Atlantic ocean; Ondes de Rossby; Courant variabilité; Cap Vert; Subtropical Est; Océan Atlantique Nord. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-374.pdf |
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| Chevaldonne, Pierre; Jollivet, Didier; Vangriesheim, Annick; Desbruyeres, Daniel. |
| Deep-sea hydrothermal-vent habitats are typically linear, discontinuous, and short-lived. Some of the vent fauna such as the endemic polychaete family Alvinellidae are thought to lack a planktotrophic larval stage and therefore not to broadcast-release their offspring. The genetic evidence points to exchanges on a scale that seems to contradict this type of reproductive pattern. However, the rift valley may topographically rectify the bottom currents, thereby facilitating the dispersal of propagules between active vent sites separated in some cases by 10s of kilometers or more along the ridge axis. A propagule flux model based on a matrix of intersite distances, long-term current-meter data, and information on the biology and ecology of Alvinellidae was... |
| Tipo: Text |
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| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44780/44597.pdf |
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| Mullineaux, Lauren; Speer, Kevin; Thurnherr, Andreas; Maltrud, Matthew; Vangriesheim, Annick. |
| Introduction : Dispersal processes play an important role in the structure and dynamics of many terrestrial and marine communities, and they are especially critical in deep-sea hydrothermal vent ecosystems. These systems are patchy and transient, and most of the species inhabiting them cannot survive elsewhere, so successful dispersal (usually via a larval stage) is essential for maintaining viable populations and species ranges. To understand the mechanisms of larval dispersal, we need to know larval life spans and the transport dynamics of deep-water flows near vent habitats. When these values are measured for a species in a given region, a maximum dispersal distance can be calculated and compared to the geographic spacing between vent fields in that... |
| Tipo: Text |
Palavras-chave: Numerical models; Dipersal potential; Larvae; Flow regime; Hydrothermal vent; Deep sea ecosystems. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-898.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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| Huthnance, John M.; Coelho, Henrique; Griffiths, Colin R.; Knight, Philip J.; Rees, Andrew P.; Sinha, Bablu; Vangriesheim, Annick; White, Martin; Chatwin, Paul G.. |
| The physical context for ocean margin exchange at Goban Spur is described. Observations adjacent to, prior to and during the Ocean Margin EXchange (OMEX) project of 1993-1996 are used. They include currents measured on moorings, drogued-buoy tracks; temperature and other data from CTD profiles, especially as indicators of vertical mixing; evidence from models, particularly for turbulence causing vertical mixing. These data are combined in estimates of (seasonally dependent) mean flow, tidal currents, other current variability, exchange and mixing over the main cross-slope section studied in OMEX and in nearby and contrasted locations (aided by the use of earlier and adjacent measurements). Causative physical processes are discussed: potentially northward... |
| Tipo: Text |
Palavras-chave: Estimation; Physical process; Tidal current; Mixing; Ocean margin exchange; Physical oceanography. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-740.pdf |
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| Cosson-sarradin, Nathalie; Sibuet, Myriam; Paterson, Glj; Vangriesheim, Annick. |
| This study assesses how differences in nutrient flux and bottom currents affect the diversity and trophic structure of deep-sea polychaete communities from the tropical northeast Atlantic at 20 degrees to 21 degrees N latitude. Faunal assemblages were studied from 3 sets of USNEL box cores (0.25 m(2)) taken at depths of 1700, 3100 and 4600 m. In terms of primary productivity, the cores were taken beneath water which is eutrophic, mesotrophic and oligotrophic, respectively. Total polychaete abundance, abundance of dominant species, and faunal similarity and diversity were compared among the 3 sites. Polychaete abundance decreased with increasing depth. Community structure reflected environmental characteristics as well as the influence of coastal upwelling.... |
| Tipo: Text |
Palavras-chave: Deep sea; Tropical Atlantic; Diversity; Polychaete community; Environmental conditions. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00179/28978/27398.pdf |
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| Guiavarc'H, Catherine; Treguier, Anne-marie; Vangriesheim, Annick. |
| Current meter measurements on the continental slope of the Gulf of Guinea (at 7 degrees 20'S and 1300 m depth) have revealed biweekly oscillations of the currents, bottom intensified and oriented along the bathymetry. We develop a three-dimensional primitive equation model of the Gulf of Guinea to study the oscillations and their forcing mechanism. The high resolution (1/12 degrees) regional model reproduces remarkably well the main characteristics of the deep currents on the continental slope. Experiments with different forcings demonstrate that the biweekly variability at 1300 m depth is remotely forced by equatorial winds. Deep Yanai waves generated by the wind propagate eastward along the equator. Upon reaching the African coast, the energy propagates... |
| Tipo: Text |
Palavras-chave: Gulf of Guinea; Numerical modeling; Coastal trapped waves. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4476.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: 23 | |
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