|
|
|
| Registros recuperados: 42 | |
|
| |
|
| |
|
|
| Mazurie, Joseph; Stanisiere, Jean-yves; Bouget, Jean-francois; Langlade, Aime; Leclerc, Emilie; Quinsat, Kevin; Herve, Gilles; Augustin, Jean-marie; Ehrhold, Axel; Sinquin, Jean-marc; Meidi-deviarni, Ika; Goubert, Evelyne; Cochet, Helene; Dreano, Alain. |
| This study (“Risco”), implicating both industry, socio-economic experts and biologists, was funded by the Regional Council of Brittany, for 3 years (2010-2012), to investigate about the causes of oysters (Crassostrea gigas) mortalities in the bay of Quiberon (South Brittany, France). The protocol including both a sonar and video visualization of the bottom, and a monthly survey of 15 experimental oyster structures, allowed to assess the risk due to predation. A clear spatial distribution of the predatory effect was evidenced, with starfish (Asterias rubens and Marthasterias glacialis) predominating in the North-East sector, and boring snails (Ocenebra erinacea and Pterophora inornata) in the South-Center area.. The main mortalities from these predators... |
| Tipo: Text |
Palavras-chave: Baie de Quiberon; Huître; Crassostrea gigas; Risque; Mortalité; Prédation; Étoiles de mer; Bigorneaux perceurs; Risco; Bay of Quiberon; Oyster; Crassostrea gigas; Risk; Mortality; Predation; Starfish; Oyster drills; Risco. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00180/29130/27534.pdf |
| |
|
|
| Stanisiere, Jean-yves; Mazurie, Joseph; Bouget, Jean-francois; Langlade, Aime; Gabellec, Raoul; Retho, Michael; Quinsat, Kevin; Leclerc, Emilie; Cugier, Philippe; Dussauze, Morgan; Menesguen, Alain; Dumas, Franck; Gohin, Francis; Augustin, Jean-marie; Ehrhold, Axel; Sinquin, Jean-marc; Goubert, Evelyne; Dreano, Alain. |
| The project “Risco”, supported by the “Pôle Mer” and funded by the Regional Council of Brittany, deals with specific risks of mortality of oysters, Crassostrea gigas, cultivated on the bottom, in a subtidal bay of South Brittany : the bay of Quiberon (56, France). Massive mortalities of oysters were reported in summer 2006 in this bay, exclusively located in the deep muddy area with a positive gradient eastward. A validated biogeochemical model was applied in order to simulate the dissolved oxygen over 2000-2006 : it revealed several episodes of hypoxia, more or less intense according to years, but with the same spatial distribution. This approach proved 2006 to be the most hypoxic year since 2000. The hypoxia was due to a rare conjunction of 3 factors :... |
| Tipo: Text |
Palavras-chave: Baie Quiberon; Crassostrea gigas; Huître; Mortalité; Croissance; Hypoxie; Oxygène; Modèle; Upwelling; Loire; Vilaine; Quiberon; Crassostrea gigas; Oyster; Mortality; Growth; Hypoxia; Oxygen; Model; DEB; Upwelling; Loire; Vilaine. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00180/29131/27535.pdf |
| |
|
|
| Le Gall, Bernard; Authemayou, Christine; Ehrhold, Axel; Paquette, Jean-louis; Bussien, Denise; Chazot, Gilles; Aouizerat, Arthur; Pastol, Yves. |
| An exceptional structural picture of the immerged Variscan basement, offshore the Leon metamorphic domain, is supplied by high-resolution LiDAR and echosounder data recorded in the Molene archipelago, western Brittany (France). Various types of fabrics are identified and, from in situ rock sample analyses further combined with field structural data, are interpreted on a lineament trajectory map as the trace of magmatic and tectonic structures. Our onshore/offshore study leads us to propose a two-phase kinematic model that emphasizes the role of a strike-slip duplex in an EW-trending relay zone linking the North Armorican and Pierres Noires ductile shear zones (NASZ, PNSZ). Dextral shearing occurred within a transtensional setting, synchronously with... |
| Tipo: Text |
Palavras-chave: Armorican massif; Leon metamorphic domain; Offshore structural mapping; LiDAR records; Dextral ductile shearing; U/Pb zircon/monazite dating. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00194/30490/28895.pdf |
| |
|
|
| Durand, M.; Mojtahid, M.; Maillet, G. M.; Proust, J. -n.; Lehay, D.; Ehrhold, Axel; Barre, A.; Howa, H.. |
| We used sedimentological and foraminiferal characteristics of four sedimentary cores, supported by paleogeographical and historical data, to reconstruct the depositional history of the inner Loire estuary (Near Saint-Nazaire, France) and the response of benthic foraminifera to the mid- to late-Holocene marine flooding of the incised valley. These were further used to evaluate the consequent changes in estuarine morphological and hydro-sedimentary patterns during this time period. Our results described significant changes in hydro-sedimentary dynamics over the past ~ 6 kyrs BP. At our location, these changes expressed the combined influence of marine (e.g., tide, storm waves) and fluvial dynamics (e.g., floods), which are linked, on a broader scale, to... |
| Tipo: Text |
Palavras-chave: Macrotidal estuary; Mid-latitude estuary; Holocene paleoenvironment; Estuarine facies; Benthic foraminifera; Sea-level change. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00347/45849/45511.pdf |
| |
|
| |
|
|
| Gregoire, Gwendoline; Ehrhold, Axel; Le Roy, Pascal; Jouet, Gwenael; Garlan, Thierry. |
| Long-studied with respect to its sedimentological features (1897), the Bay of Brest (Western Britanny, France) is a textbook example of a tide-dominated estuary. Characterised by macrotidal conditions, this estuary system is sheltered from the open sea (Iroise Sea) by a narrow strait that partitions the wave tide influences and continental/marine inputs. Sediments are supplied to the bay both by rivers (the Aulne and Elorn rivers) and by marine tidal currents. This study presents new analyses of detailed facies and morphological patterns, based on the integration of multisource data compiling seabed sampling, swath and LIDAR bathymetry, and backscatter imagery. The Main Map, at a scale of 1:90,000, contains (1) a sedimentological distribution using the... |
| Tipo: Text |
Palavras-chave: Morpho-sedimentological cartography; Tide-dominated; Estuary system; Estuarine sedimentation; Backscatter imagery; Bay of Brest. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00334/44492/44224.pdf |
| |
|
|
| Lambert, Clément; Vidal, Muriel; Penaud, Aurélie; Le Roy, Pascal; Goubert, Evelyne; Pailler, Yvan; Stephan, Pierre; Ehrhold, Axel. |
| Sedimentological, palynological, and micropalaeontological studies carried out throughout the first half of the Holocene, during the Mesolithic/Neolithic transition in the Bay of Brest (i.e. 9200–9000 and 6600–5300 cal. BP) and in the Bay of Douarnenez (i.e. 9200–8400 cal. BP), allowed characterizing coastal environmental changes under the increasing influence of the relative sea-level rise. The gradual flooding of the two studied sites implied a transition from river valleys to oceanic bays as revealed by the gradual retreat of salt marsh environments, as detected through palynological analysis. In addition, these high-resolution studies highlight the regional imprint of the North Atlantic millennial climate variability in north-western coastal... |
| Tipo: Text |
Palavras-chave: Benthic foraminifera; Climate variability; Dinoflagellate cysts; Human impacts; Palaeoenvironments reconstructions; Pollen grains. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00472/58341/60920.pdf |
| |
|
|
| Michel, Guillaume; Dupre, Stephanie; Baltzer, Agnes; Ehrhold, Axel; Imbert, Patrice; Pitel, Mathilde; Loubrieu, Benoit; Scalabrin, Carla; Lazure, Pascal; Marie, Louis; Geldof, Jean-baptiste; Deville, Eric. |
| Inactive and mostly elongated pockmarks of 100–200 m in dimension were recently discovered on the South Aquitaine Margin continental slope. They are distributed at water depths greater than 350 m in both interfluve and sediment-wave areas, and are strongly controlled by the sedimentary morphology and architecture. Water column and seafloor backscatter and sub-bottom profiler data do not exhibit present-day or past gas evidence, e.g., massive and continuous gas releases at the seabed and fossil methane-derived authigenic carbonates. It is thus proposed that the pockmarks originated from a shallow source and result from relatively recent and short-duration gas or water expulsion events. Former near-bottom currents may have contributed to the elongation of... |
| Tipo: Text |
Palavras-chave: Pockmark; Fluid; Seabed morphology; Aquitaine slope; GIS; Currents. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00413/52491/53279.pdf |
| |
|
|
| Hamon, Dominique; Ehrhold, Axel; Houlgatte, Eric; Kerdoncuff, Julien; Gaffet, Jean-dominique; Caisey, Xavier; Alix, Anne-sophie; Oger-jeanneret, Helene. |
| Poster présenté aux Journées REBENT Brest les 13 et 14/10/2011 (2ème atelier de restitution Rebent Bretagne. Dans le cadre du programme de surveillance DCE, et en lien avec le projet REBENT, il a été entrepris en 2008-2009 de cartographier et de caractériser les principaux bancs de maërl distribués dans 9 masses d'eaux autour de la Bretagne, et faisant l'objet pour la plupart d'un suivi annuel de leur biodiversité, assuré par l'IUEM (LEMAR). |
| Tipo: Text |
|
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00042/15275/12631.pdf |
| |
|
| |
|
| |
|
|
| Ehrhold, Axel; Chevalier, Claire; Alix, Anne-sophie; Autret, Elodie; Caisey, Xavier; Drussel, Benjamin; Gaffet, Jean-dominique; Hamon, Dominique; Houlgatte, Eric; Pluquet, Fabrice; Biscara, Laurie; Choisnet, Justine; Bajjouk, Touria. |
| In 2000 Ifremer launched and coordinated the development of a monitoring strategy for the REBENT network (REseau BENThique) in order to assess the aftermath of the “Erika” oil spill which took place in December 1999. Its aim is to provide consistent baseline knowledge on coastal benthic habitats, as well as to develop a monitoring tool that detects changes at various spatial and temporal scales. Sector-based seabed habitat mapping in shallow water (< 50 m deep), is currently being conducted throughout Brittany's coastal waters using a combination of geoacoustic marine systems together with ground-truthing using biological grab sampling and seabed observations. Due to the extended area, the overlap of soft and rocky bottoms, and contrasting hydrological... |
| Tipo: Text |
Palavras-chave: Rebent; Trégor-Goëlo; Bréhat; Cartographie d’habitats; Sonar latéral; Macrofaune benthique; Peuplements; Crépidule; Maërl; Sédiments; Morphologie; Dynamique sédimentaire; Rebent; Trégor-Goëlo; Bréhat archipelago; Marine habitat mapping; Sidescan sonar; Benthic macrofauna; Communities; Crepidula bed; Maerl; Sediment; Morphology; Bedload transpor. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00280/39161/37724.pdf |
| |
|
|
| Delebecq, Gaspard; Schmidt, Sabine; Ehrhold, Axel; Latimier, Marie; Siano, Raffaele. |
| The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and gibberellic acid, two molecules commonly used in seed priming. Dinoflagellates were revived from sediments dated to approximately 150 years ago (156 ± 27, 32 cm depth), extending the known record age of cyst viability previously established as around one century. A culture suspension of sediments mixed with melatonin and gibberellic acid solutions as biostimulants exhibited germination of 11 dinoflagellate taxa... |
| Tipo: Text |
Palavras-chave: Alexandrium; Cyst; Dinoflagellate; Gibberellic acid; Melatonin; Paleoecology; Priming; Scrippsiella; Resurrection ecology. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00627/73960/73321.pdf |
| |
|
|
| Baltzer, Agnes; Reynaud, Marine; Ehrhold, Axel; Fournier, Jerome; Cordier, Celine; Clouet, Helene. |
| About a decade ago, a large field of pockmarks, covering an overall area of 36 km(2) was discovered in water depths of < 30m in the central part of the Bay of Concarneau (Southern Brittany, France). This field, composed of features from 5 m to 35 m in diameter and < 1 m in depth, is characterized by unusual high densities of pockmarks, up to 5840 per square kilometre. Geophysical data correlated with sedimentary samples acquired in 2005 and 2009 show that pockmarks and their immediate surroundings are associated with dense tubes benches cover, built by a filter-feeding amphipod: Haploops nirae, forming original benthic communities. Two complementary surveys were carried out in April 2011 (Pock and Ploops) and April 2014 (Pock and Tide), on the... |
| Tipo: Text |
Palavras-chave: Géophysique; Marée; Failles; Gaz; Geophysics; Pockmarks; Tide; Turbidity; Gas; Chimneys pipes; Concarneau. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00410/52107/52938.pdf |
| |
|
|
| Lambert, Clément; Penaud, A.; Vidal, Marie-odile; Gandini, C.; Labeyrie, L.; Chauvaud, Laurent; Ehrhold, Axel. |
| The Holocene period (last 11,700 years BP) has been marked by significant climate variability over decadal to millennial timescales. The underlying mechanisms are still being debated, despite ocean–atmosphere–land connections put forward in many paleo-studies. Among the main drivers, involving a cluster of spectral signatures and shaping the climate of north-western Europe, are solar activity, the North Atlantic Oscillation (NAO) varying atmospheric regimes and North Atlantic oceanic gyre dynamics. Over the last 2500 years BP, paleo-environmental signals have been strongly affected by anthropogenic activities through deforestation and land use for crops, grazing, habitations, or access to resources. Palynological proxies (especially pollen grains and... |
| Tipo: Text |
|
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00665/77715/79803.pdf |
| |
|
| |
|
| |
|
|
| Dupré, Stephanie; Loubrieu, Benoit; Pierre, C.; Scalabrin, Carla; Guerin, Charline; Ehrhold, Axel; Ogor, Andre; Gautier, Emeric; Ruffine, Livio; Biville, Romain; Saout, Johan; Breton, C; Floodpage, J.; Lescanne, M.. |
| A few thousand (2612) seeps are releasing microbial methane bubbles from the seafloor at the Aquitaine Shelf edge (Bay of Biscay) at shallow water depths (140‐220 m). This methane contributes to the formation of meter‐scale subcircular carbonate structures, which are (sub‐)outcropping over 375 km2. Based on in situ flow rate measurements and acoustic data, and assuming steady and continuous fluxes over time, the methane entering the water column is estimated to 144 Mg/yr. Microbial methane circulation has been on‐going for at least a few thousand years. This discovery highlights the importance of microbial methane generation, disconnected from deep thermogenic sources and gas hydrates, at continental shelves. The shelf edge may be viewed as a focus area... |
| Tipo: Text |
Palavras-chave: Microbial methane; Continental shelf; Fluid emissions; High‐resolution acoustics; Aquitaine Margin; Methane‐derived authigenic carbonates. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00618/72982/72057.pdf |
| |
| Registros recuperados: 42 | |
|
|
|
