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Cold-seep-like macrofaunal communities in organic- and sulfide-rich sediments of the Congo deep-sea fan ArchiMer
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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Early diagenesis in the sediments of the Congo deep-sea fan dominated by massive terrigenous deposits: Part II – Iron–sulfur coupling ArchiMer
Taillefert, Martial; Beckler, Jordon S.; Cathalot, Cecile; Michalopoulos, Panagiotis; Corvaisier, Rudolph; Kiriazis, Nicole; Caprais, Jean-claude; Pastor, Lucie; Rabouille, Christophe.
Deep-sea fans are well known depot centers for organic carbon that should promote sulfate reduction. At the same time, the high rates of deposition of unconsolidated metal oxides from terrigenous origin may also promote metal-reducing microbial activity. To investigate the eventual coupling between the iron and sulfur cycles in these environments, shallow sediment cores (< 50 cm) across various channels and levees in the Congo River deep-sea fan (~5000 m) were profiled using a combination of geochemical methods. Interestingly, metal reduction dominated suboxic carbon remineralization processes in most of these sediments, while dissolved sulfide was absent. In some ‘hotspot’ patches, however, sulfate reduction produced large sulfide concentrations which...
Tipo: Text Palavras-chave: Sediment diagenesis; Iron reduction; Sulfate reduction; Deep-sea fans.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00389/50068/52254.pdf
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Early diagenesis in the sediments of the Congo deep-sea fan dominated by massive terrigenous deposits: Part III – Sulfate- and methane- based microbial processes ArchiMer
Pastor, Lucie; Toffin, Laurent; Decker, Carole; Olu, Karine; Cathalot, Cecile; Lesongeur, Francoise; Caprais, Jean-claude; Bessette, Sandrine; Brandily, Christophe; Taillefert, M.; Rabouille, C..
Geochemical profiles (SO42-, H2S, CH4, δ13CH4) and phylogenetic diversity of Archaea and Bacteria from two oceanographic cruises dedicated to the lobes sediments of the Congo deep-sea fan are presented in this paper. In this area, organic-rich turbidites reach 5000 m and allow the establishment of patchy cold-seep-like habitats including microbial mats, reduced sediments, and vesicomyid bivalves assemblages. These bivalves live in endosymbiosis with sulfur-oxidizing bacteria and use sulfides to perform chemosynthesis. In these habitats, unlike classical abyssal sediments, anoxic processes are dominant. Total oxygen uptake fluxes and methane fluxes measured with benthic chambers are in the same range as those of active cold-seep environments, and oxygen is...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00376/48767/49164.pdf
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Hydrogen dynamics in soil organic matter as determined by C-13 and H-2 labeling experiments ArchiMer
Paul, Alexia; Hatte, Christine; Pastor, Lucie; Thiry, Yves; Siclet, Francoise; Balesdent, Jerome.
Understanding hydrogen dynamics in soil organic matter is important to predict the fate of H-3 in terrestrial environments. One way to determine hydrogen fate and to point out processes is to examine the isotopic signature of the element in soil. However, the non-exchangeable hydrogen isotopic signal in soil is complex and depends on the fate of organic compounds and microbial biosyntheses that incorporate water-derived hydrogen. To decipher this complex system and to understand the close link between hydrogen and carbon cycles, we followed labeled hydrogen and labeled carbon throughout near-natural soil incubations. We performed incubation experiments with three labeling conditions: 1 - (CH)-C-13-H-2 double-labeled molecules in the presence of (H2O)-H-1;...
Tipo: Text
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00371/48198/48314.pdf
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Recherche et isolement de molécules bioactives dans des invertébrés marins IRD
Pastor, Lucie.
Tipo: Text Palavras-chave: LAGON; RECIF CORALLIEN; INVERTEBRE AQUATIQUE; SUBSTANCE NATURELLE; ACTIVITE BIOLOGIQUE; MEDICAMENT; METHODE D'ANALYSE; EXTRACTION; PURIFICATION; CHROMATOGRAPHIE; TEST BIOLOGIQUE.
Ano: 2002 URL: http://www.documentation.ird.fr/hor/fdi:010031558
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The Congolobe project, a multidisciplinary study of Congo deep-sea fan lobe complex: Overview of methods, strategies, observations and sampling ArchiMer
Rabouille, C.; Olu, Karine; Baudin, F.; Khripounoff, Alexis; Dennielou, Bernard; Arnaud-haond, Sophie; Babonneau, Nathalie; Bayle, Christophe; Beckler, J.; Bessette, Sandrine; Bombled, B.; Bourgeois, S.; Brandily, Christophe; Caprais, Jean-claude; Cathalot, Cecile; Charlier, K.; Corvaisier, R.; Croguennec, Chantal; Cruaud, Perrine; Decker, Carole; Droz, L.; Gayet, Nicolas; Godfroy, Anne; Hourdez, S.; Le Bruchec, J.; Saout, Johan; Le Saout, Marie-helene; Lesongeur, Francoise; Martinez, P.; Mejanelle, L.; Michalopoulos, P.; Mouchel, Olivier; Noel, Philippe; Pastor, Lucie; Picot, M.; Pignet, Patricia; Pozzato, L.; Pruski, A. M.; Rabiller, Manuella; Raimonet, M.; Ragueneau, O.; Reyss, J. L.; Rodier, Philippe; Ruesch, Blandine; Ruffine, Livio; Savignac, F.; Senyarich, C.; Schnyder, J.; Sen, Arunima; Stetten, E.; Sun, Ming Yi; Taillefert, M.; Teixeira, S.; Tisnerat-laborde, N.; Toffin, Laurent; Tourolle, Julie; Toussaint, F.; Vetion, G.; Jouanneau, J. M.; Bez, M..
The presently active region of the Congo deep-sea fan (around 330 000 km2), called the terminal lobes or lobe complex, covers an area of 2500 km2 at 4700–5100 m water depth and 750–800 km offshore. It is a unique sedimentary area in the world ocean fed by a submarine canyon and a channel-levee system which presently deliver large amounts of organic carbon originating from the Congo River by turbidity currents. This particularity is due to the deep incision of the shelf by the Congo canyon, up to 30 km into the estuary, which funnels the Congo River sediments into the deep-sea. The connection between the river and the canyon is unique for major world rivers. In 2011, two cruises (WACS leg 2 and Congolobe) were conducted to simultaneously investigate the...
Tipo: Text Palavras-chave: Chemosynthetic habitats; Congo deep-sea fan; Fine sediment; Sedimentation rate; Seafloor morphology; Turbidite; Vesicomyidae.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00335/44580/44298.pdf
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The influence of bottom currents on the Zambezi Valley morphology (Mozambique Channel, SW Indian Ocean): In situ current observations and hydrodynamic modelling ArchiMer
Miramontes, Elda; Penven, Pierrick; Fierens, Ruth; Droz, Laurence; Toucanne, Samuel; Jorry, Stephan; Jouet, Gwenael; Pastor, Lucie; Silva Jacinto, Ricardo; Gaillot, Arnaud; Giraudeau, Jacques; Raisson, François.
Mixed turbidite-contourite systems can be found in oceans where bottom currents and turbidity currents interact. The Zambezi turbidite system, located in the Mozambique Channel (SW Indian Ocean), is one of the largest sedimentary systems in the world in length and area of the related catchments. The oceanic circulation in the Mozambique Channel is intense and complex, dominated by eddies flowing southwards and deep currents flowing northwards along the Mozambican margin. Current measurements obtained from moorings at 3400–4050 m water depth in the Zambezi and Tsiribihina valleys show periods of intense currents at the seafloor with peaks of 40–50 cm s−1 that last up to one month and are not related to turbidity currents. These strong bottom-current events...
Tipo: Text Palavras-chave: Contourite; Turbidity current; Mixed system; Oceanic circulation; Mooring; ADCP; ROMS model; Bedform.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00476/58743/61269.pdf
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Transient early diagenetic processes in Rhône prodelta sediments revealed in contrasting flood events ArchiMer
Pastor, Lucie; Rabouille, C.; Metzger, E.; De Chanvalon, A. Thibault; Viollier, E.; Deflandre, B..
Floods carry sediments to river deltas and the coastal zone, but little is known about the geochemical evolution of this particulate material deposited over a short period of time. Here, we studied two recent contrasting flood deposits in the Rhône River prodelta area (northwestern Mediterranean Sea). We monitored the porewater and solid-phase chemistry over periods ranging from a few days to 6 months after deposition. Non-steady state diagenetic processes associated with episodic deposition promote a wide spectrum of transient redox conditions in the shallow prodelta region of the Rhône. Specific attributes of diagenetic responses depend on the sources of flood material and scale (thickness) of deposition. The first flood unit of 20–30 cm was composed of...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00449/56049/57568.pdf
Registros recuperados: 8
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