Consulta: creatorFacets:"Ehrhold, Axel"
Registros recuperados: 42
Data/hora: 07/06/2024 05:32:15

Environmental factors affecting maerl bed structure in Brittany (France)
Provedor de dados: 5
Autores: Dutertre, Mickael; Grall, Jacques; Ehrhold, Axel; Hamon, Dominique.
This study used a large spatial scale approach in order to better quantify the relationships between maerl bed structure and a selection of potentially forcing physical factors. Data on maerl bed structure and morpho-sedimentary characteristics were obtained from recent oceanographic surveys using underwater video recording and grab sampling. Considering the difficulties in carrying out real-time monitoring of highly variable hydrodynamic and physicochemical factors, these were generated by three-dimensional numerical models with high spatial and temporal resolution. The BIOENV procedure indicated that variation in the percentage cover of thalli can best be explained (correlation = 0.76) by a combination of annual mean salinity, annual mean nitrate...
Tipo: Text
Palavras-chave: Benthic habitats; Brittany; Environmental factors; Estuary; Large spatial scale; Maerl.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00280/39089/37816.pdf

Réseau de surveillance benthique (REBENT) – Région Bretagne. Approche sectorielle subtidale : Identification et caractérisation des habitats benthiques du secteur Morlaix
Provedor de dados: 5
Autores: Ehrhold, Axel; Hamon, Dominique; Chevalier, Claire.
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 (&lt; 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 overlap of soft and rocky bottoms, and contrasting hydrological conditions, the...
Tipo: Text
Palavras-chave: Rebent; Baie de Morlaix; Cartographie d’habitats; Sonar latéral; Macrofaune benthique; Peuplements; Dynamique sédimentaire; Figures sédimentaires; Rebent; Morlaix bay; Mapping; Sidescan sonar; Benthic macrofauna; Communities; Bedload transport; Bedforms.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00152/26276/24360.pdf

Control factors of Holocene sedimentary infilling in a semi-closed tidal estuarine-like system: the bay of Brest (France)
Provedor de dados: 5
Autores: Gregoire, Gwendoline; Le Roy, Pascal; Ehrhold, Axel; Jouet, Gwenael; Garlan, Thierry.
This study details the sedimentary infilling of an original tidal-dominated estuary system during the final stage of the last marine transgression. The Bay of Brest is confined and connects the rivers Elorn and Aulne, to the sea of Iroise by a narrow strait encasing a well preserved paleo-channel. The compilation of high- and very-high-resolution bathymetric and seismic data, constrained by sediments datations, allows us to classify the paleo-morphology of the bay into three stepped domains: the paleo-valley floor surrounded by fluvial terraces, the central plateau, and the shallow embayments. Taking into account the main factors controlling the infilling, including sea-level rise, substratum morphology, and hydrodynamics, the stratigraphic scheme of the...
Tipo: Text
Palavras-chave: Tide-dominated estuary; Incised-valley; Holocene infill; Seismic stratigraphy; Estuarine processes; Bay of Brest.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00358/46968/46883.pdf

Space-time evolution of a large field of pockmarks in the Bay of Concarneau (NW Brittany)
Provedor de dados: 5
Autores: 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 &lt; 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 &lt; 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

Tectonique extensive tertiaire à l’extrémité occidentale du Massif armoricain. Les blocs tiltés d’Ouessant et de Molène
Provedor de dados: 5
Autores: Le Gall, Bernard; Ehrhold, Axel; Authemayou, Christine.
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00363/47441/47468.pdf

Reconnaissance cartographique de bancs de maërl distribués sur le littoral breton
Provedor de dados: 5
Autores: 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

Imagerie LiDAR du socle hercynien immergé de l’archipel de Molène, Ouest Massif Armoricain. Evidence d’un duplex ductile décrochant et d’intrusions syntectoniques
Provedor de dados: 5
Autores: Le Gall, Bernard; Authemayou, Christine; Ehrhold, Axel.
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00363/47439/47464.pdf

Du sonar au microscope : les fonds marins auscultés aux abords du cap de Flamanville
Provedor de dados: 5
Autores: Hamon, Dominique; Ehrhold, Axel; Chevalier, Claire; Caisey, Xavier; Gaffet, Jean-dominique; Alix, Anne-sophie.
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00064/17507/15021.pdf

Directive Cadre sur l'Eau - Région Bretagne : Reconnaissance cartographique de bancs de maërl distribués dans les masses d'eaux côtières de référence. Convention Ifremer-Agence de l'Eau Loire-Bretagne. Volume 1, Rapport de synthèse, Volume 2, Résultats analytiques
Provedor de dados: 5
Autores: Hamon, Dominique; Ehrhold, Axel; Houlgatte, Eric.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00025/13664/10854.pdf

Late Pleistocene evolution of the mixed siliciclastic and carbonate southwestern New Caledonia continental shelf/lagoon
Provedor de dados: 5
Autores: Le Roy, Pascal; Jorry, Stephan; Jouet, Gwenael; Ehrhold, Axel; Michel, Guillaume; Gautier, Valentin; Guerin, Charline.
The main island of New Caledonia (NC) is surrounded by the second largest barrier reef in the world after the Australian Great Barrier Reef. The Upper Pleistocene evolution of this barrier reef–lagoon complex offers the opportunity to examine the response of a modern mixed tropical siliciclastic/carbonate system to relative sea-level changes and to better constrain the relative role of lagoon backfilling and paleo-drainage system in sediment transfer across the shelf. This paper mainly focuses on the results of chronostratigraphic and sedimentological interpretations of new seismic, bathymetric and coring data collected in the SW NC lagoon. Several significant points are highlighted from this study and allow the construction of a refined model which...
Tipo: Text
Palavras-chave: Seismic stratigraphy; Quaternary; Incised valleys.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00461/57289/59362.pdf

Revival of ancient marine dinoflagellates using molecular biostimulation
Provedor de dados: 5
Autores: 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

The Stone Tidal Fish Weirs of the Molene Archipelago, Iroise Sea, Brittany, Western France: a long-term tradition with early megalithic origins
Provedor de dados: 5
Autores: Gandois, Henri; Stephan, Pierre; Cuisnier, David; Hulot, Olivia; Ehrhold, Axel; Paul, Marine; Le Dantec, Nicolas; Franzetti, Marcaurelio.
This reports on a project that combined evidence gleaned from aerial photographs, place-names, interviews, topography, LIDAR data, and sonar bathymetry to locate stone tidal fish weirs in the Molene Archipelago. The results were verified by diver and pedestrian visual surveys. Models of Holocene sea-level change allowed a group of possibly Late Mesolithic-Early Neolithic weirs to be recognized, with a second group broadly dated to the later Neolithic-Early Bronze Age. The construction of these long megalithic structures is compared to the funerary monuments for which the Molene Archipelago is well known, in terms of technique, cost, and societal organization.
Tipo: Text
Palavras-chave: Tidal weirs fish traps Mol&lt; Bold&gt; E&lt; /bold&gt; Ne Archipelago megalithic constructions sea-level change Mesolithic Neolithic.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00430/54208/55907.pdf

Striking forest revival at the end of the Roman Period in north-western Europe
Provedor de dados: 5
Autores: 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

Les facteurs de contrôle du remplissage Holocène dans un système estuarien dominé marée : La rade de Brest (Bretagne)
Provedor de dados: 5
Autores: Gregoire, Gwendoline; Le Roy, Pascal; Ehrhold, Axel; Jouet, Gwenael; Garlan, Thierry.
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00363/47412/47412.pdf

Haliotis, nouvel outil pour l’étude des habitats benthiques dans les très petits fonds
Provedor de dados: 5
Autores: Ehrhold, Axel; Cordier, Celine; Pluquet, Fabrice; Alix, Anne-sophie; Monpert, Coralie; Autret, Elodie; Hamon, Dominique.
Les besoins d'inventaires et de suivis des habitats benthiques côtiers, de même que la nécessité de mieux comprendre leur fonctionnement, conduisent depuis plusieurs années à mettre en place des actions à différentes échelles d'observation spatiales et temporelles sur l’ensemble des façades métropolitaines. L’application du Réseau Benthique au pilote breton en est une parfaite illustration. Le Rebent a ainsi soutenu dès 2001 le projet d’une embarcation spécialisée, destinée à relayer dans la frange littorale les moyens acoustiques mis en oeuvre sur les navires côtiers plus au large, et capable d’assurer une investigation des fonds sur de grandes superficies, avec un fort pouvoir de résolution. Ce projet de vedette porté par l’Ifremer a été rendu possible...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00283/39440/37888.pdf

Etude d’un champ de pockmarks associé à un peuplement de Haploops dans la Baie de Concarneau : apport de la prospection géophysique THR
Provedor de dados: 5
Autores: Baltzer, Agnes; Ehrhold, Axel; Rigolet, Carinne; Dubois, Stanislas; Cordier, Celine.
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00281/39232/37792.pdf

Modern morpho-sedimentological patterns in a tide-dominated estuary system: the Bay of Brest (west Britanny, France)
Provedor de dados: 5
Autores: 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

Cartographie prédictive du champ de laminaires du plateau Molène sur la base des données physiques et biologiques
Provedor de dados: 5
Autores: Bajjouk, Touria; Rochette, Sebastien; Ehrhold, Axel; Cordier, Celine; Laurans, Martial; Tourolle, Julie; Hamdi, Anouar; Tourolle, Julie; Gaffet, Jean-dominique; Caisey, Xavier; Vasquez, Mickael; Populus, Jacques.
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00280/39159/37722.pdf

Réseau de surveillance benthique – Région Bretagne. Approche sectorielle subtidale : Identification et caractérisation des habitats benthiques du secteur Trégor-Goëlo
Provedor de dados: 5
Autores: 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 (&lt; 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

Approche multi-échelles de la cartographie des habitats benthiques des substrats meubles subtidaux : application à la frange côtière de Bretagne nord
Provedor de dados: 5
Autores: Chevalier, Claire; Dutertre, Mickael; Hamon, Dominique; Ehrhold, Axel; Gentil, Franck; Thiebaut, Eric; Bajjouk, Touria.
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00281/39231/37791.pdf

Using acoustic and lidar acquisitions for mapping soft and hard bottom communities in the bay of Morlaix (North Brittany french coast)
Provedor de dados: 5
Autores: Ehrhold, Axel; Bajjouk, Touria; Hamon, Dominique; Chevalier, Claire; Gorman, Daniel; Populus, Jacques.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00281/39233/37793.pdf

Les risques conchylicoles en Baie de Quiberon. Troisième partie : le risque d’hypoxie pour l’huître creuse Crassostrea gigas. Rapport final du projet Risco 2010-2013
Provedor de dados: 5
Autores: 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

Cartographie prédictive du champ de Laminaires du plateau Molénais sur la base des données physiques et biologiques. Recueil des données acoustiques, biologiques et sédimentaires nouvellement acquises depuis septembre 2010
Provedor de dados: 5
Autores: Ehrhold, Axel; Bajjouk, Touria; Populus, Jacques; Cordier, Celine; Gorman, Daniel; Gaffet, Jean-dominique; Caisey, Xavier.
Tipo: Text
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00281/39176/37737.pdf

Influence des facteurs hydrodynamiques sur la répartition et l'évolution morpho-sédimentaire : exemple de la Rade de Brest (Finistère)
Provedor de dados: 5
Autores: Gregoire, Gwendoline; Ehrhold, Axel; Jouet, Gwenael; Augris, Claude; Simplet, Laure; Le Roy, Pascal; Garlan, Thierry.
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00285/39614/38108.pdf

Approche sectorielle subtidale : Identification et caractérisation des habitats benthiques du secteur Glénan (Réseau de surveillance benthique - Région Bretagne)
Provedor de dados: 5
Autores: Ehrhold, Axel; Blanchet, Aline; Hamon, Dominique.
Ifremer launched and coordinated the development of a strategy for the REBENT network (REseau BENThique) in 2000 to monitor the aftermath of the "Erika" oil spill in December 1999. Its aim is to provide consistent baseline knowledge about coastal benthic habitats and constitute a monitoring tool to detect changes at various scales over time and space. Sector-based seabed habitat mapping in shallow water (&lt; 50 m deep), is currently being conducted throughout Brittany's coastal waters through a combination of geoacoustic marine systems and ground-truthing using biological grab sampling and seabed observations.  Sedimentological and biological results on Glenan area emphasize a great diversity of subtidal habitats and marine species recognized. Sidescan...
Tipo: Text
Palavras-chave: Haploops; Maerl; Bedforms; Bedload transport; Communities; Benthic macrofauna; Sidescan sonar; Habitats mapping; Glenan; Rebent; Haploops; Maërl; Figures sédimentaires; Dynamique sédimentaire; Peuplements; Macrofaune benthique; Sonar latéral; Cartographie d'habitats; Glénan; Rebent.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/rapport-2301.pdf

Pockmarks on the South Aquitaine Margin continental slope: The seabed expression of past fluid circulation and former bottom currents
Provedor de dados: 5
Autores: 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

Forêts de laminaires à Molène : approches multi-échelles des fonds rocheux de l’archipel
Provedor de dados: 5
Autores: Ehrhold, Axel; Bajjouk, Touria; Cordier, Celine; Le Nilliot, Philippe; Hamdi, Anouar; Drussel, Benjamin; Guerin, Charline; Le Gall, Bernard; Populus, Jacques.
Tipo: Text
Palavras-chave: Habitat; Laminaires; Systèmes acoustiques; Lidar; Géomorphologie; MNT.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00281/39230/37790.pdf

Modélisation des flux sédimentaires charriés dans la baie du Mont-Saint-Michel (Manche, France)
Provedor de dados: 5
Autores: Ehrhold, Axel; Guillou, Sylvain; Auffret, J; Garlan, T; Nguyen, K.
A study of the sediment bedload in the Mont-Saint-Michel bay is presented here. It combines the use of a 2DH numerical model and a pattern of sediment bedload transport established on the analysis of the statements of sidescan imagery combined with a dense groundwork of sedimentary grab samples. Results show the role of tidal currents asymetry in the realistic bioclastic sand transfert from the subtidal environment to the coast and the divergence of sedimentary dynamic between the maritime bay to the West and the tidal delta to the East. This in-shore transfer is responsable of the Holocene prism construction. The model reproduces tidal sedimentary dynamics with the immediate surroundings of the Mont-Saint-Michel. It shows the interest of the modeling of...
Tipo: Text
Palavras-chave: Mont Saint Michel bay; Sediment; Sidescan; Bedload transport; Hydrodynamic model; Baie du Mont Saint Miche; Sédiment; Sonar latéral; Débit massique; Modèle hydrodynamique.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-522.pdf

Palaeoenvironmental reconstructions during the Meso- to Neolithic transition (9.2–5.3 cal. ka BP) in Northwestern France: Palynological evidences
Provedor de dados: 5
Autores: 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

Dynamique de comblement d'un bassin sédimentaire soumis à un régime mégatidal : Exemple de la Baie du Mont-Saint-Michel
Provedor de dados: 5
Autores: Ehrhold, Axel.
This work has been performed in a DRET/CNRS convention and related to the problems of sedimentary dynamics in a bay dominated by tidal currents. It combines the descriptive study of the morphosedimentary units with the modeling of bedload processes. At the South channel Isles, the Mont-Saint-Michel bay is well known for his exceptional tidal range. It's open to the offshore with two broad master channels on both sides from the Chausey's archipelago. On the coarse sedimentary cover of pebbles and gravels, sediments dynamic series of some  plurikilometres sandy ribbons. These sands are temporarily stocked in lonely bedforms and in coastal maritime banks, sandwaves field of Granville and tide delta. The coastal banks are connected in the littoral prism. They...
Tipo: Text
Palavras-chave: Bedload transport; Hydrodynamic numerical model; Sediment color; Crepidule; Coastal banks; Sandwaves; Sand ribbons; Swells; Tidal currents; Sedimentary prism; Norman breton Gulf; Transport solide; Code numérique; Couleur des sédiments; Crépidule; Bancs côtiers; Dunes tidales; Rubans sableux; Houle; Courants de marée; Prisme sédimentaire; Golfe normand breton.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/1999/these-3232.pdf

Cartes sédimentologiques et morpho-bathymétriques de la baie de Morlaix et de sa région
Provedor de dados: 5
Autores: Ehrhold, Axel.
La baie de Morlaix, fermée par l’île de Batz à l’ouest, les falaises de Primel-Trégastel à l’est, et l’archipel de la Méloine au nord, est un des joyaux de la côte bretonne appréciée pour sa diversité biologique mais beaucoup moins connue par ses particularités géologiques. Sa morphologie sous-marine est une sorte de labyrinthe, composé de nombreux îlots et hauts-fonds, à l’origine d’une mosaïque de provinces sédimentaires où se confrontent à chaque marée, courants et sédiments. Cette synthèse (au format papier et numérique) regroupe les travaux menés depuis une dizaine d’années par l’Ifremer sur les fonds de cette région. Elle répond ainsi à la préoccupation d’une large communauté curieuse de son environnement : la morphologie du littoral, la dynamique et...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00285/39603/38097.pdf

Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)
Provedor de dados: 5
Autores: Lambert, Clement; Penaud, Aurelie; Vidal, Muriel; Klouch, Khadidja; Gregoire, Gwendoline; Ehrhold, Axel; Eynaud, Frederique; Schmidt, Sabine; Ragueneau, Olivier; Siano, Raffaele.
For the first time a very high resolution palynological study (mean resolution of 1 to 5 years) was carried out over the last 150 years in a French estuarine environment (Bay of Brest; NW France), allowing direct comparison between the evolution of landscapes, surface water, and human practices on Bay of Brest watersheds, through continental (especially pollen grains) and marine (phytoplanktonic microalgae: cysts of dinoflagellates or dinocysts) microfossils. Thanks to the small size of the watersheds and the close proximity of the depositional environment to the mainland, the Bay of Brest represents an ideal case study for palynological investigations. Palynological data were then compared to published palaeo-genetic analyses conducted on the same core...
Tipo: Text
Palavras-chave: Pollen grains; Dinoflagellate cysts; Estuarine dynamics; River runoff; Climate variability.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00410/52110/52813.pdf

LiDAR offshore structural mapping and U/Pb zircon/monazite dating of Variscan strain in the Leon metamorphic domain, NW Brittany
Provedor de dados: 5
Autores: 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

Approche bidimensionnelle des transports sédimentaires à partir des variations granulométriques des sédiments superficiels : Exemple de la partie occidentale de la baie du Mont Saint-Michel
Provedor de dados: 5
Autores: Ehrhold, Axel; Auffret, Jean-paul.
Grain size trends in relation to net sediment transport pathways are examined, using sorne cornmonly-used grain size pararneters. The results of the model are compared with the net sediment transport pathways established on the basis of the bedfonn asymmetry. The 3 types of trends are calculated using an increasing characteristic distance and differents grids of seabed sediment samples. lt is shown that : (1) the characteristic distance defined by Gao et Collins (maximum spatial sampling interval) changes with these two factors to a maximal value; (2) in an heterogeneous sedimentary environment, the correlations between calculated vectors and observed transport pathways are better by using sand size distributions and (3) the residual pattern rises to sixty...
Tipo: Text
Ano: 1996
URL: http://archimer.ifremer.fr/doc/00285/39620/38111.pdf

Cartographie bio-sédimentaire des fonds subtidaux de l’archipel de Chausey. Programme HEIMa. Rapport final
Provedor de dados: 5
Autores: Fournier, Jérome; Desroy, Nicolas; Ehrhold, Axel; Autret, Elodie; Cordier, Celine; Janson, Anne-laure.
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00280/39163/37752.pdf

Mid- to late-Holocene environmental evolution of the Loire estuary as observed from sedimentary characteristics and benthic foraminiferal assemblages
Provedor de dados: 5
Autores: 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

Etude morpho-sédimentaire du plateau rocheux de la Méloine (Finistère nord). Recueil des données acoustiques, sédimentaires et d’observations acquises pendant les missions GEOMELOINE et NEOMELEC’H en 2014
Provedor de dados: 5
Autores: Ehrhold, Axel; Gautier, Emeric; Roubi, Angelique; Guerin, Charline; Gaillot, Arnaud; Gaffet, Jean-dominique; Caisey, Xavier.
Etude morpho-sédimentaire du plateau rocheux de la Méloine (Finistère nord). Recueil des données acoustiques, sédimentaires et d’observations acquises pendant les missions GEOMELOINE et NEOMELEC’H en 2014
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00280/39109/37662.pdf

The Aquitaine Shelf edge (Bay of Biscay): a primary outlet for microbial methane release
Provedor de dados: 5
Autores: 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

Réseau de surveillance benthique – Région Bretagne. Approche sectorielle subtidale : Identification et caractérisation des habitats benthiques du secteur Quiberon
Provedor de dados: 5
Autores: Ehrhold, Axel; Hamon, Dominique; Chevalier, Claire; Gaffet, Jean-dominique; Caisey, Xavier; Blanchet, Aline; Alix, Anne-sophie.
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 (&lt; 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. The study area in the bay of Quiberon is characterised by a large array of sedimentological...
Tipo: Text
Palavras-chave: Rebent; Baie de Quiberon; Cartographie d’habitats; Sonar latéral; Macrofaune benthique; Peuplements; Dynamique sédimentaire; Figures sédimentaires; Rebent; Quiberon bay; Mapping; Sidescan sonar; Benthic macrofauna; Communities; Bedload transport; Bedforms.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00281/39179/37741.pdf

Les risques conchylicoles en Baie de Quiberon. Deuxième partie : le risque de prédation sur l’huître creuse Crassostrea gigas. Rapport final du projet Risco 2010-2013
Provedor de dados: 5
Autores: 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

Structuration sédimentaire et dynamique de l’ensemble des fonds de la baie de Morlaix (Manche). Évolution du secteur des pierres noires depuis 30 ans
Provedor de dados: 5
Autores: Ehrhold, Axel; Autret, Elodie; Gaffet, Jean-dominique; Caisey, Xavier.
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00281/39235/37795.pdf

Etude morpho-sédimentaire du plateau rocheux de la Méloine (Finistère nord). Méthodologie appliquée aux traitements des données et résultats sur la distribution des roches dans l’archipel
Provedor de dados: 5
Autores: Ehrhold, Axel; Gautier, Emeric; Roubi, Angelique; Guerin, Charline; Gaillot, Arnaud; Gaffet, Jean-dominique; Caisey, Xavier.
Etude morpho-sédimentaire du plateau rocheux de la Méloine (Finistère nord) Méthodologie appliquée aux traitements des données et résultats sur la distribution des roches dans l’archipel.
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00280/39111/37664.pdf