Consulta: creatorFacets:"Allain, Gwenhael"
Registros recuperados: 11
Data/hora: 06/06/2024 02:20:06

The influence of environment and spawning distribution on the survival of anchovy (Engraulis encrasicolus) larvae in the Bay of Biscay (NE Atlantic) investigated by biophysical simulations
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal.
A growth and survival model of the early life stages was run along virtual drift trajectories tracked in a hydrodynamic model to simulate the annual recruitment process of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). These biophysical simulations concerning three different years were analysed in order to investigate the influence of environment and spawning dynamics on the survival of larvae and juveniles. The location of space-time survival windows suggested major environmental mechanisms involved in simulated recruitment variability at the different scales - retention of larvae and juveniles in favourable habitats over the shelf margins and turbulence effects. These small-scale and meso-scale mechanisms were related to the...
Tipo: Text
Palavras-chave: Turbulence; Retention; Recruitment; Physical biological interactions; Larval survival; IBM; Biscay; Anchovy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3423.pdf

Etude épidémiologique des mortalités de naissain d'huîtres creuses observées en 2008 en France - Etude épidémiologique analytique. Rapport final
Provedor de dados: 5
Autores: Allain, Gwenhael.
A la suite des mortalités massives d'huîtres creuses (Crassostrea gigas) observées en France dans tous les bassins de production ostréicoles, une étude épidémiologique a été engagée. Débutée en octobre 2008, son objectif est d'aider à l'identification de la (ou les) causees) de ces mortalités. Elle comprend deux parties. Une première phase, descriptive, a consisté à décrire la distribution des mortalités dans le temps et l'espace, ainsi que la population touchée, puis à formuler des hypothèses concernant l'implication d'un ou de plusieurs facteurs de risque dans le phénomène observé. La seconde partie est une étude analytique dont l'objectif est de tester les hypothèses formulées lors de l'enquête épidémiologique descriptive, en étudiant l'association...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00306/41766/40979.pdf

Summer mortality outbreaks of French Pacific oysters Crassostrea gigas in 2008 and 2009
Provedor de dados: 5
Autores: Renault, Tristan; Allain, Gwenhael; Arzul, Isabelle; Chollet, Bruno; Cobret, Laetitia; De Decker, Sophie; Faury, Nicole; Ferrand, Sylvie; Francois, Cyrille; Garcia, Celine; Haffner, Philippe; Joly, Jean-pierre; Miossec, Laurence; Morga, Benjamin; Nicolas, Jean-louis; Omnes, Emmanuelle; Pepin, Jean-francois; Saulnier, Denis; Schikorski, David; Segarra, Amelie.
Abnormal mortality outbreaks occurred in the majority of Pacific oyster (Crassostrea gigas) producing areas in France in 2008 during the summer period. These outbreaks were usually sudden and severe (up to 100%) and affected essentially spat (oysters less than 1 year-old) and juveniles (12 to 18 month-old oysters). Crassostrea gigas was the single affected species Mortality outbreaks were first observed from mid May to mid June in Brittany, Vendée, Charente Maritime and Mediterranean coast A second episode of massive mortality events was reported at the end of June and the beginning of July. All oyster production sites were affected except some particular locations including Arcachon Bay and Brittany. Mortality occurred latter in Arcachon Bay in August....
Tipo: Text
Palavras-chave: Abnormal mortality; Oysters; Crassostrea gigas; Pathogens.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00014/12554/9420.pdf

Biophysical modelling of larval drift, growth and survival for the prediction of anchovy (Engraulis encrasicolus) recruitment in the Bay of Biscay (NE Atlantic)
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal; Grellier, Patrick.
Fish recruitment is the result of the integration of small-scale processes affecting larval survival over a season and large oceanic areas. A hydrodynamic model was used to explore and model these physical-biological interaction mechanisms and then to perform the integration from individual to population scales in order to provide recruitment predictions for fisheries management. This method was applied to the case of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). The main data available to investigate survival mechanisms were past growth (otolith) records of larvae and juveniles sampled at sea. The drift history of these individuals was reconstructed by a backtracking procedure using hydrodynamic simulations. The relationships...
Tipo: Text
Palavras-chave: Recruitment; Physical biological interactions; Individual based models; Biscay; Anchovy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3422.pdf

Environmental and stock effects on the recruitment of anchovy in the Bay of Biscay : a multivariate analysis
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal.
Variability in anchovy recruitment in Biscay is temptatively explained using variables from the stock and from the environment during the ichtyoplankton phase. Anchovy recruitment depends on many different processes : weight of adults and proportion of multiple spawners (age 2), river discharges, upwelling events at the coast and at the shelf break. Meteorological variables (wind, rain, tempe rature ) are forcing effects on the sea but they are not the effective processes that govern the production in the sea. So they do not relate directly to the survival of larvae and to recruitment. In Biscay, many different physical processes are active and used by anchovy which spawns in different physical systems (river plumes, open ocean enrichment systems)....
Tipo: Text
Palavras-chave: Bio-physical coupling; Recruitment; Anchovy; Hdrodynamics; Step by step regression.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00391/50190/50814.pdf

Etude de la fécondité de l’huître creuse dans le bassin d’Arcachon en 2013 en lien avec la qualité de l’eau. Compte-rendu final du programme FeLiBA
Provedor de dados: 5
Autores: Bernard, Ismael; Allain, Gwenhael; Auby, Isabelle; Plus, Martin; Drean, Tugdual; Gasmi, Sonia; David, Valérie; Pouvreau, Stephane; Maurer, Daniele.
De 2009 à 2011, le captage à Arcachon fut particulièrement mauvais. Des pontes tardives associées à de faibles quantités de larves “petites” indiquaient un problème probablement au niveau de la maturation ou de la ponte. Le programme FéLiBA consiste en un zoom, pour l’année 2013, sur la Fécondité des huîtres creuses en Lien avec la qualité de l’eau du Bassin d’Arcachon. Ce programme s’est traduit par différentes actions de terrain. Tout d’abord, la maturation des huîtres issues du captage d’Arcachon ou de Marennes-Oléron a été suivie à Arcachon (site du Tès) et comparée avec celle de la Rade de Brest (pointe du Château) au cours de l’année 2013. Puis, un bilan de la maturation des huîtres sauvages d’Arcachon a été établi fin juin 2013. La ponte a également...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00179/29002/27428.pdf

Spatial patterns in the condition index of the wild Pacific oyster Crassostrea gigas in a macrotidal coastal ecosystem: Influence of tidal processes and beyond
Provedor de dados: 5
Autores: Gasmi, Sonia; Bernard, Ismael; Pouvreau, Stephane; Maurer, Daniele; Schaal, Gauthier; Ganthy, Florian; Cominassi, Louise; Allain, Gwenhael; Sautour, Benoit; David, Valerie.
In macrotidal coastal ecosystems, spatial heterogeneity of the water column properties is induced by both oceanic and continental influences. Hydrodynamic processes generate a land-sea gradient of environmental conditions, affecting the biological performances of sedentary organisms. The aim of the present study is to establish an extensive spatial assessment in the reproductive investment of the wild Pacific oyster Crassostrea gigas in Arcachon Bay. This is done by looking for a relationship between the Lawrence and Scott condition index (LSCI) and two tidal processes: the immersion level (IL) and the local oceanic flushing time (LoFt). The LSCI of C. gigas was assessed, just before gamete release, at 68 sampling stations in Arcachon Bay. Oyster...
Tipo: Text
Palavras-chave: Reproductive investment; Crassostrea gigas; Macrotidal lagoon; Immersion level; Oceanic flushing; Environmental variability.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00357/46803/46670.pdf

First results of an epidemiological study on oyster (Crassostrea gigas) mortality events in France during summer 2008
Provedor de dados: 5
Autores: Miossec, Laurence; Allain, Gwenhael; Arzul, Isabelle; Francois, Cyrille; Garcia, Celine; Cameron, Angus.
Abnormal mortalities occurred in most oyster producing areas in France during the summer of 2008.  The mortalities were sudden and severe (up to 100%) and mainly affected 6 to 18 month old juveniles.  Only Crassostrea gigas species was affected.  The cause of the mortality was unclear but OsHV-1 virus and bacteria belonging to Vibrionaceae family were frequently detected in affected populations. An epidemiological study was commenced in autumn 2008 in order to identify factors associated with, and the cause (or causes) of these mortalities.  This paper presents the results of the first (descriptive) part of this investigation.  The objectives were to identify the affected population and to describe the pattern of mortalities in time and space.  Mortality...
Tipo: Text
Palavras-chave: France; Crassostrea gigas; Oyster; Mortality; Epidemological study.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/acte-6772.pdf

Modélisation biophysique pour la prévision du recrutement
Provedor de dados: 5
Autores: Allain, Gwenhael.
Exploited fish populations are dependent on recruitment (i.e. size of the new year class) to sustain their abundance. Recruitment variations are related to hydroclimatic variations and may accentuate the detrimental effects of fishing. Recruitment prediction requires accurate fisheries oceanographic tools, which are expected to be more reliable than large-scale correlation analyses between fish abundance and climate variables.  Recruitment is the result of the integration over a season and large oceanic areas of processes affecting larval survival, which are dependent on small-scale mechanisms. Hydrodynamic models are a tool to perform this integration. This thesis aims at exploring and modelling physical-biological interaction mechanisms in order to...
Tipo: Text
Palavras-chave: Anchovy; Upwelling; Turbulence; Retention; Fisheries management; Population dynamics; Stock environment interaction; Stock recruitment relation; Scale integration; Individual based models; Survival; Growth; Otolith; Physical biological interactions; Prediction; Recruitment; Turbulence; Rétention; Méso échelle; Intégration des échelles; Modèle de survie; Modèle de ponte; Modèles individu centrés; Modèles de corrélation; Modèles stochastiques; Juvéniles; Larves; Otolithe; Modèle de croissance; Interactions physique biologie; Prévision; Recrutement.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/these-5.pdf

Etude épidémiologique descriptive des mortalités exceptionnelles d'huîtres creuses enregistrées sur le littoral français en 2008
Provedor de dados: 5
Autores: Miossec, Laurence; Allain, Gwenhael; Arzul, Isabelle; Francois, Cyrille; Garcia, Celine; Cameron, Angus.
En 2008, des mortalités massives d'huîtres creuses (Crassostrea gigas) ont été recensées en France pendant l'été. Ce phénomène, observé de façon récurrente sur les côtés françaises depuis le milieu des années 70, a présenté un caractère exceptionnel en 2008 car il a été observé simultanément dans tous les bassins ostréicoles. De plus, les taux de mortalité calculés ont été particulièrement élevés (80 à 100 % pour de nombreux lots). La détection, fréquente et souvent simultanée, d'herpèsvirus OsHV1 et de plusieurs bactéries de la famille des Vibrionacées dans le cadre de la surveillance menée par le réseau national Repamo (réseau de pathologie des mollusques) a mis en évidence le caractère infectieux de l'épisode épidémique 2008. Une étude épidémiologique a...
Tipo: Text
Palavras-chave: France; Crassostrea gigas; Huîtres; Mortalités; Epidémiologie.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/acte-6771.pdf

Les pratiques culturales peuvent-elles permettre de réduire la surmortalité du naissain d'huîtres creuses? Récapitulatif des essais d'élevage et expérimentations zootechniques menés sur le territoire français entre 2008 et 2010
Provedor de dados: 5
Autores: Soletchnik, Patrick; Mazurie, Joseph; Allain, Gwenhael; Bedier, Edouard; Benabdelmouna, Abdellah; Blin, Jean-louis; Bouquet, Anne-lise; Cochet, Hélène; Degremont, Lionel; Gaussem, Florian; Gervasoni, Erika; Glize, Philippe; Petton, Bruno; Roussel, Pierre-yves; Pernet, Fabrice.
This paper summarizes knowledge about relations between husbandry practices and oyster spat mortalities since 2008 in France. These relations are strictly analyzed from a panel of experiments set on the shore (in outdoor experiments) by Ifremer teams and technical institutes all over French coasts. Results show some practices are able to reduce spat mortality with some influencing factors relevant of spat quality (sanitary status, natural or genetic selection) or husbandry practices. Spat “free” of virus is able to survive up to 90% when it is isolated and confined in ponds or nursery, during an epidemic crisis. When outbreaks occurred in oyster beds, natural or nursery spat died in almost same proportions. In 2010, some studies conducted in Mediterranean...
Tipo: Text
Palavras-chave: Surmortalité; Naissain; Huître creuse; OsHV-1; Pratiques culturales; Mortality; Spat; Cupped oyster; Crassostrea gigas; OsHV-1; Cultural practices.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00032/14280/25847.pdf