Résumé : La forêt tropicale humide guyanaise est située dans le grand ensemble Amazonien, qui est un point chaud des enjeux sur la biodiversité et la conservation des forêts tropicales. Une connaissance de l’âge et des taux d’accroissement des arbres est primordiale pour comprendre la dynamique de ces écosystèmes Cependant, l’absence de conditions hivernales sous les tropiques rend difficile la lecture de l’histoire dans les bois de ces forêts. En se plaçant dans le champ de l’anatomie fonctionnelle, cette thèse à caractère exploratoire avait pour but, à travers différentes approches, i) de suivre l’activité cambiale de quatre espèces ligneuses durant deux ans par prélèvements de micro-carottes, ii) de faire une étude dendrochronologique sur une espèce guyanaise, iii) d’utiliser la variation de la signature isotopique comme marqueur de croissance (ou d’histoire) et iv) de tester la pollution aérienne consécutive aux lancements de la fusée Ariane comme marqueurs de la croissance. L’examen bi-mensuel de l’activité cambiale a montré que tous les arbres présentent des alternances de quasi repos et de forte activité du cambium durant les deux années. Ces périodes de ralentissement ont été plus marquées chez Parkia nitida (décidue), Parkia velutina (décidue) et Schefflera morototoni (sempervirente). On observe donc des périodes de ralentissement de l’activité du cambium aussi bien chez deux espèces décidues que chez une espèce sempervirente. Il n’y a pas de patron universel de liaisons deux à deux entre pluviométrie intra-annuelle, phénologie de la feuillaison et activité cambiale même si des analogies fortes existent au cas par cas entre deux espèces pour une relation donnée. L’étude dendrochronologique chez Parkia nitida a mis en évidence la présence de cernes de croissance bien distincts et annuels. La limite de cerne se caractérise par une fine bande de parenchyme marginal renfermant de nombreux cristaux d’oxalate de calcium. A l’échelle de l’arbre, la croissance secondaire est homogène et elle est relativement synchrone au sein d’individus de cette espèce dans le même lieu. Cependant, l’influence des paramètres climatiques testés, comme la température et les précipitations, sur la croissance radiale annuelle est faible sur la période considérée. Ces deux premières études montrent que, dans le contexte de la Guyane française, la saisonnalité annuelle très marquée de la pluviométrie ne se traduit pas par un signal suffisamment fort pour synchroniser l’ensemble du fonctionnement des arbres. Néanmoins, elle influence clairement, au cas par cas soit la feuillaison, soit la floraison, soit la croissance cambiale. Les autres méthodes de marquage de la croissance (i.e. isotopie et chimie) entreprises demandent à être approfondies. Les bois des espèces de forêt tropicale humide se caractérisant en moyenne par un pourcentage élevé du plan ligneux occupé par les parenchymes axiaux, il serait important d’entreprendre une étude approfondie de leur rôle en tant qu’accumulateurs de substances potentiellement utiles pour la défense du bois dans l’arbre contre les xylophages. L’évolution dans le temps (périodicité, vieillissement chimique) des solutions de défense mises en place dans le bois est une piste intéressante pour la dendrochronologie
The rainforest of French Guiana is located in the Amazonian region, which is a hotspot of biodiversity, thus leading to several issues about conservation in tropical forests. Knowledge of the age and growth rate of trees is essential to understand the dynamics of these ecosystems. However, due to the lack of winter conditions it is difficult to read the story in the wood of these tropical forests. In the topic of functional anatomy, this thesis intends through different approaches i) to monitor the cambial activity of four tree species during two years sampling micro-cores, ii) to make a dendrochronological study on a Guyanese species iii) to use the variation of the isotopic signature as a marker of growth (or history) and iv) to test air pollution following launches of the Ariane rocket as markers of growth. The bi-monthly review of cambial activity showed that all trees have almost alternating rest and high activity of cambium in both years. These downturns have been more pronounced in Parkia nitida (deciduous), Parkia velutina (deciduous) and Schefflera morototoni (evergreen). We observe periods of cambial activity downturn in two deciduous species as well as in an evergreen species. There is no universal pattern of connections in pairs between rainfall intra-annual phenology of leafing and cambial activity although strong similarities exist in each case between two species for a given association. The dendrochronological study in Parkia nitida highlights the presence of distinct annual growth rings. The limit is characterized by a thin band of marginal parenchyma containing numerous crystals of calcium oxalate. At tree scale, secondary growth is homogeneous and relatively synchronous within individuals of this species in the same location. However, the influence of tested climatic parameters, such as temperature and precipitation on the annual radial growth, is low over the considered period. The first two studies showed that, in the environment of French Guiana, marked annual seasonality of rainfall does not affect in a strong way the behavior of the trees. Nevertheless, those rainfalls have an influence either on leafing, flowering or cambial growth. Other methods of marking growth (i.e. isotopic and chemical) intended require further investigations. Axial parenchyma represents a high average percentage in the wood of rainforest species: it could be important to investigate more precisely its role as accumulators of potentially useful substances involved in wood defense against borers. The evolution throughout time (periodicity, chemical aging) of defense mechanisms in woods is an interesting way for dendrochronology.

http://www.theses.fr/2013AGUY0605/document

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Continuous Global Positioning System (CGPS) position time series from eastern North America constrain the pattern and magnitude of regional crustal deformation. Initial analysis delineates consistent uplift patterns, as expected from glacial isostatic adjustment (GIA) predictions, but the associated horizontal deformation is not definitive, in part due to the short time periods for a significant number of the available stations. We employ an eigenpattern decomposition in order to define a unique, finite set of deformation patterns for this continuous GPS data. Similar in nature to the empirical orthogonal functions historically employed in the analysis of atmospheric and oceanographic phenomena, the method derives the eigenvalues and eigenstates from the diagonalization of the correlation matrix using a Karhunen-Loeve expansion (KLE). The KLE technique is used to identify the important modes in both time and space for the CGPS data, modes that potentially include signals such as horizontal and vertical GIA, tectonic strain, and seasonal effects. Here we filter both the vertical and horizontal velocity patterns on different spatiotemporal scales in order to study the potential geophysical sources, after the removal of correlated and random noise. The method is successful in disaggregating the linear vertical signal from more variable and less spatially correlated signals. The vertical and horizontal results are compared to the predictions of the ICE-3G GIA loading model with a number of plausible mantle viscosity profiles. The horizontal velocity analysis allows for qualitative differentiation between several potential GIA models and suggests that, with longer time series, this technique can be employed to remove correlated noise and improve estimates of crustal strain patterns and their sources.
ISSN: 0033-4553

hal-00795454
https://hal.archives-ouvertes.fr/hal-00795454
DOI : 10.1007/s00024-011-0420-1

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : In recent years, the use of fads in Martinique has evolved from an experimental stage to a productive one. This transformation results in the pitching up of operational device park by the regional fishery committee. Nevertheless, this technical change in fishing practices is not implemented in a homogeneous way all around the island; some differences exist especially between the Atlantic and the Caribbean coasts. From surveys carried out during an annual cycle on two main landing sites, this study describes the pelagic fishing activity around fads and in the open sea. A comparison of fishing strategies adopted in different places as well as an analysis of the results obtained by the fishing units in terms of species (size of catches and daily yields) allow to describe the progress made in the implementation adoption of this new fishing practice. For several fishermen, fishing around fads has become an exclusive job, practised all year round. For others, fads is used in addition to traditional fishing activity on flotsam, "Miquelon" fishing and keeps a seasonal character.Original Abstract: Au cours des recentes annees, l'utilisation des DCP en Martinique est passee du stade experimental au stade operationnel. Cette mutation se traduit par la prise en charge du parc de dispositifs operationnels par le comite regional des peches. Toutefois, l'adoption de cette nouvelle technique d'exploitation ne s'effectue pas de facon homogene dans toutes les communes de l'ile, des differences existent notamment entre les cotes Atlantique et Caraibe. A partir d'enquetes effectuees pendant un cycle annuel, sur deux principaux points de debarquement, cette etude decrit l'activite de peche des poissons pelagiques avec ou sans DCP. Une comparaison des strategies de peche developpees dans les differents sites ainsi qu'une analyse des resultats obtenus par les unites de peche en termes d'especes, de taille des captures, de rendement journalier permettent de decrire la progression differenciee de l'adoption de cette nouvelle activite halieutique. Pour certains pecheurs, la peche sous DCP est devenue un metier exclusif, pratique tout au long de l'annee. Pour d'autres, le DCP est utilise en complement de l'activite traditionnelle de peche sous bois derivants, " peche a Miquelon ", et conserve un caractere saisonnier.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15298/12657.pdf
http://archimer.ifremer.fr/doc/00042/15298/

Éditeur(s) : Université Paris 7 – Denis Diderot
Résumé : Sea surface salinity (SSS) influences numerous oceanic phenomena, for instance surface water ventilation, deep water formation and thermohaline circulation. SSS also controls some ocean-atmosphere coupled processes, such as the intensity of freshwater flux and the penetration of heat flux and turbulence. Salinity is more difficult to measure than temperature from in situ surveys, which results in 20 times less data being currently available. Moreover, sea surface temperature (SST) is routinely estimated from satellites, which is not possible yet for SSS. Two space missions will fill this gap soon: SMOS from the European Space Agency and Aquarius/SAC-D from NASA and CONAE. To contribute to the SMOS project, we propose a method for estimating SSS from current satellite observations and for studying the mechanisms governing its variability. We developed a simplified model of the ocean mixed layer, based on the "slab mixed layer" formulation (Frankignoul et Hasselmann, 1977). This 2D horizontal model is implemented over the global ocean, using a near 100 km resolution, and integrated during a climatological year. Air-sea fluxes are taken from the ECMWF meteorological model (ERA40 reanalysis) and the surface currents are provided by altimeter data (SSALTO-DUACS analysis). The mixed layer depth (MLD) is derived from SST observations, using an original inversion technique. The MLD fields obtained from this inversion are well correlated to in situ estimates. This effective depth represents the air-sea fluxes penetration and ensures consistency between fluxes, les currents and SST. We first validate the simulation through examination of the heat balance in north-eastern Atlantic, by comparing to measurements and models from the POMME experiment. Then we study the salinity balance in the global domain, in terms of its geographical distribution and seasonal evolution. Equilibrium between the various processes appears generally more complex than for temperature. Noteworthy, the role of atmospheric flux is less predominant (22%), while geostrophic advection (33%) and diapycnal mixing (22%) contribute more strongly. Our results indicate this model succeeds in reconstructing SSS variability over most of the oceans. Daily SSS variations are also simulated, whereas they are not represented in current observed data at a global scale. Owing to its simplicity and fast computation, the model will be useful to the SMOS mission. It can help for the measurement calibration/validation and provide a first guess estimate to the sophisticated algorithm required for SSS restitution.
La salinité de surface des océans (SSS) influence de nombreux phénomènes océaniques, parmi lesquels la ventilation des eaux de surface, la formation d'eaux profondes et la circulation thermohaline. Elle détermine aussi certains processus couplés océan-atmosphère, notamment l'intensité du flux d'eau douce, la pénétration du flux de chaleur et de la turbulence. La mesure in situ de salinité est plus compliquée que celle de température, si bien qu'on dispose actuellement de 20 fois moins de données pour cette propriété. De plus, la température de surface (SST) est couramment estimée par satellite, ce qui n'est pas encore le cas de la SSS. Deux missions spatiales vont prochainement combler cette lacune : le satellite SMOS de l'Agence Spatiale Européenne et le satellite Aquarius/SAC-D de la NASA et de la CONAE. En préparation du projet SMOS, nous proposons une méthode pour estimer la SSS à partir des observations satellitaires actuelles et étudier les mécanismes de sa variabilité. Nous avons développé un modèle simplifié de couche mélangée océanique, basé sur la formulation "slab mixed layer" (Frankignoul et Hasselmann, 1977). Ce modèle 2D horizontal est implémenté sur l'océan global, avec une résolution proche de 100 km, et intégré au cours d'une année climatologique. Les flux air-mer proviennent du modèle météorologique ECMWF (réanalyse ERA40) et les courants de surface sont issus de l'altimétrie (analyse SSALTO-DUACS). La profondeur de la couche mélangée (MLD) est dérivée des observations de SST, grâce à une technique d'inversion originale. La MLD obtenue par inversion est bien corrélée aux estimations basées sur des données in situ. Cette profondeur effective représente la pénétration des flux air-mer et assure la cohérence entre les flux, les courants et la SST. La simulation est d'abord validée en examinant le bilan de chaleur dans l'Atlantique Nord-Est, par comparaison aux mesures et aux modèles de l'expérience POMME. Puis le bilan de salinité est étudié dans le domaine global, en termes de distribution géographique et d'évolution saisonnière. L'équilibre entre les différents processus est généralement plus complexe que pour la température. Notamment, le rôle du flux atmosphérique est moins prépondérant (22%), tandis que l'advection géostrophique (33%) et le mélange diapycnal (22%) contribuent fortement. Nos résultats montrent que ce modèle parvient à restituer la variabilité de la SSS sur la majeure partie des océans. Le modèle simule aussi les variations journalières de SSS, qui ne sont pas représentées à l'échelle globale dans les observations actuelles. Grâce à sa simplicité et à sa rapidité, le modèle pourra être utile dans le cadre de SMOS. Il pourra aider à la calibration/validation de la mesure et fournir une estimation a priori pour l'algorithme complexe nécessaire à la restitution de la SSS.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2302.pdf
http://archimer.ifremer.fr/doc/00000/2302/

Résumé : Marine capture fisheries in Jamaica is primarily artisanal in nature ansd is conducted maiinly by fishermen operating from canoes. Approximately 95% of these fishermen operate on the coastal shelf and its associated banks. The commercial species harvested comprise bottom-dwelling, coral reef species and free swimming species of finfish. Other fishery resources of commercial value include marine shrimp, conch and lobsters. Catch statistics are not available for all species, but the Department of Fisheries reports a slight decline in fishery production with production decreasing from 16 milion lbs in 1990, despite the fact that fishing efforts have doubled. Over this period the number of registered fishermen has grown from 12 000 to 16 000, al of whom are engaged in full-time fishing. There arealso part-time fishermen who are not registered. The decline in fish catch is accompanied by a decrease in fish size and quality, suggesting that the fisheries are under pressure and have already exceeded optimum production in relation to vailable resources. As a result the economic returns to fishermen are declining. There are also other problems, such as high incidence of conflicts among fishermen at sea, the high cost of purchasing boats, outboard engine fuel, and equipment, with together with the dangers involved in fishing offshore (piracy, and praedial larceny) create serious social ans economic difficulties for fishermen. Notwithstanding, there is an apparent move on the part of the fishermen to leave the industryor to seek alternative forms of employment. In fact, the Department ofFisheries reports that it is still reciving applications for new licences to operate fishing boats. This is probably due to the fact that where the basis of a community is fishing, it becomes difficult to introduce alternative forms of employment, such as cottage industries, village crafts and other trades. In 1987 the Jamaica Department of Fisheries prepared a Management plan which proposed several conservation measures to promote the efficient use of fisheries resources and to control the development of the Fishery in such a way that the country would receive highest benefits. Adequate attention was given to limitations on fishing gear, institution of closed seasons and related legislation. Strategies to diversify the marine fishing were also proposed. The 1990 five year Devlopment Plan for marine fisheries also focuses on proper resource management in order to reverse trends associated with the overexploitation of marine resources. According to the plan, emphasis will be placed on inland fisheries and mariculture in order to reduce pressure on the fisheries. Inland fisheries in the form of freshwater fish fanning has expanded significantly over the past 10 years with production increasing from less than 0,5 million lbs. in 1980 to in excess of 6.0 million lbs. in 1989. However, some freshwater fish farmers are already experiencing serious competition for water usage and, to a lesser extent for land from crop-producing farmers. The Ministry of Agriculture is of the view that marine cage culture technologically has the potential for introduction in Jamaica . This technologyhas been successfully developed in Norway and the technology is currentlty being experimentally utilized in several countries in the area. The technology, if widely utilized in Jamaica, couls significantly reduce pressure on fisheries, making fishing more cost effective and improve the economic returns to fishermen. Already there exist some technical and institutional capabilities in Jamaica to support commercial development of marine cage culture. The Department of Fisheries has highly trained personnel in aquaculture and marine fisherie, some of whom are directly responsible for the success of freshwater fish fanning. In adition, the Marine Laboratory at the Univesity of the West Indies (UWI) is caarying research on hatchery facilities for marine cage farming. The Department of Fisheries will seek the collaboration ofg the marine unit at UWI which could provide fingerlings of selected marine species for cage 1
Les pêcheries de captage marin en Jamaïque sont principalement de nature artisanale et elles sont dirigées principalement par les pêcheurs qui travaillent depuis des canoës. Environ 95 % de ces pêcheurs travaillent sur la plaine côtière et ses bancs associés. Les espèces commerciales récoltées comprennent les espèces benthiques, les espèces de corail et les espèces de poisson marin de nage libre. D'autres ressources de pêcheries de valeur commerciale comprennent la crevette, la conque et le homard. Les statistiques des pêches ne sont pas disponibles pour toutes les espèces, mais le Département des Pêcheries fait état d'une légère réduction de production de pêcheries, la production se réduisant de 16 millions de livres en 1990, en dépit du fait que les efforts de la pêche ont doublé. Sur cette période le nombre de pêcheurs inscrits a augmenté de 12 000 à 16 000, dont tous sont occupés à plein temps à la pêche. Il y a aussi des pêcheurs à mi-temps qui ne sont pas inscrits. La réduction des pêches est accompagnée d'une réduction de la taille et la qualité des poissons, ce qui implique que les pêcheries sont sous pression et qu'elles ont déjà dépassé la production optimum par rapport aux ressources disponibles. En conséquence, les rendements pour les pêcheurs sont en baisse. Il y a aussi d'autres problèmes, tels qu'un taux élevé de conflits entre les pêcheurs en mer, le coût élevé pour acheter les bateaux, le combustible pour les moteurs hors-bord, et le matériel, ainsi que les dangers impliqués dans la pêche offshore (le piratage, et le vol prédial) ont créé de graves problèmes sociaux et économiques pour les pêcheurs. Néanmoins, il y a une tendance évidente chez les pêcheurs de quitter l'industrie ou de chercher du travail dans d'autres domaines. En fait, le Département des Pêcheries signale qu'il continue de recevoir des demandes de nouveaux permis pour opérer les bateaux de pêche. Ceci est probablement attribuable au fait que là où la base d'une communauté est la pêche, il est difficile d'y introduire des formes alternatives de travail, telles que l'industrie artisanale, l'artisanat de village ou d'autres métiers. Le Département des Pêcheries de la Jamaïque a préparé en 1987 un Projet de gestion qui proposait plusieurs mesures de conservation afin d'encourager l'utilisation efficace des ressources des pêcheries et de contrôler le développement de la Pêcherie de manière que le pays touche le plus de bénéfices. Une attention adéquate a été prêtée aux limitations sur les engins de la pêche, l'établissement de saisons de clôture et les législations associées. Des stratégies pour diversifier la pêche marine ont aussi été proposées. Le Plan de développement quinquennal de 1990 pour les pêcheries marines met l'accent aussi sur la gestion de ressources appropriée afin de faire reculer les tendances associées à la surexploitation des ressources marines. Selon le plan, l'accent sera mis sur les pêcheries intérieures et la mariculture afin de réduire la pression sur les pêcheries. Les pêcheries intérieures, sous la forme de l'élevage de poissons en eau douce, ont pris leur essor sur les 10 dernières années avec une production qui s'est élevée de moins de 0,5 millions de livres en 1980 pour atteindre en 1989 plus de 6.0 millions de livres. Cependant, certains pisciculteurs en eau douce expérimentent déjà une concurrence sérieuse avec les agriculteurs pour l'usage de l'eau et, dans une moindre mesure, de la terre. Le Ministère de l'Agriculture est de l'avis que l'élevage en cage marine a technologiquement le potentiel d'être introduit en Jamaïque. La technologie a été développée avec réussite en Norvège et plusieurs pays dans la région utilisent actuellement la technologie expérimentalement. La technologie, si elle était utilisée en Jamaïque, pourrait réduire de façon significative la pression sur les pêcheries, ce qui rendrait la pêche plus économique et améliorerait les rendements aux pêcheurs. Certaines capacités techniques et institutionnelles existent déjà en Jamaïque qui pourraient soutenir le développement de l'élevage en cage marine. Le Département des Pêcheries a un personnel bien formé en aquaculture et pêcherie marine, dont certains qui sont directement responsables du succès de la pisciculture en eau douce. Par ailleurs, le Laboratoire Marin à l'Université des Antilles (UWI) mène des recherches sur les installations d'écloseries pour l'élevage en cage marine. Le Département des Pêcheries demandera la collaboration de l'unité marine à l'UWI qui pourra fournir des saumoneaux d'espèces marines sélectionnées pour la cage 1.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1993/rapport-1918.pdf
http://archimer.ifremer.fr/doc/00000/1918/

Éditeur(s) : Amer Geophysical Union
Résumé : We quantify, analyze, and characterize the frequency-dependent microseismic noise recorded by worldwide distributed seismic stations. Microseismic noise is generated through the interaction of ocean waves. It is the strongest ambient noise, and it is observed everywhere on Earth. We introduce a new approach which permits us to detect polarized signals in the time-frequency domain and which we use to characterize the microseismic noise. We analyze 7 years of continuous seismograms from the global GEOSCOPE network. Microseisms are dominated by Rayleigh waves, and we therefore focus on elliptically polarized signals. The polarized signals are detected in the time-frequency domain through a degree of polarization measure. We design polarization spectra and show that microseismic noise is more strongly polarized than noise in other frequency bands. This property is used to measure the directions of the polarized noise at individual stations as a function of time and frequency. Seasonal variations are found for the back azimuths and for the number of polarized signals at many stations. We show that the back azimuth directions are robust measurements that point toward the source areas computed from ocean wave models.
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2011-07 , Vol. 12 , N. Q07014 , P. 14 p.

Droits : 2011. American Geophysical Union. All Rights Reserved.
http://archimer.ifremer.fr/doc/00041/15219/12713.pdf
DOI:10.1029/2011GC003661
http://archimer.ifremer.fr/doc/00041/15219/

Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd
Résumé : The high heterogeneity of silica cycling in coastal margins and the lack of silica data (compared to nitrogen and phosphorus) prevent the estimation of global silica retention in estuaries. In this study, the spatial and temporal variability of porewater silicic acid (Si(OH)4) profiles e that integrate benthic transport and reaction processes e was investigated at different spatial (metre, longitudinal and crosssection, intra-estuary) and temporal (tidal, seasonal) scales in two macrotidal estuaries, very close geographically but essentially differing in their shape. Studying the spatial and temporal variability of Si(OH)4 concentrations in porewaters provided evidence for the importance of transport processes, e.g. bio-irrigation, tidal pumping, resuspension and any combination of these processes, in affecting Si(OH)4 concentrations and fluxes and therefore temporary or permanent retention along the landeocean continuum. We confirm that aSiO2 (amorphous silicate) transported by rivers and estuaries clearly needs to be better characterized as it provides an important source of reactive aSiO2 to sediments. This study allows us to: (1) interrogate spatial and temporal scales, although both are most often in complete interaction; (2) design the most appropriate sampling schemes to be representative of any given system and to extrapolate at the scale of the whole estuary; (3) quantify uncertainty associated to the estimations of Si(OH)4 stocks and fluxes in this type of ecosystem, essential for budget calculations. We showed that two adjacent small macrotidal estuaries, may exhibit different behaviours regarding Si retention. Temporary retention has been observed in the meanders of the Aulne Estuary and not along the more linear Elorn Estuary, demonstrating the importance of the morphology and hydrodynamic components of the estuarine filter. Research is needed in other systems and climatic zones, but our study suggests that the typology should not only account for the different types of landeocean continuum (fjord, delta, mangrove.), but also incorporate the physical or biological attributes of the estuarine filter.
Estuarine Coastal And Shelf Science (0272-7714) (Academic Press Ltd- Elsevier Science Ltd), 2013-03 , Vol. 119 , P. 31-43

Droits : 2013 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00124/23529/22370.pdf
DOI:10.1016/j.ecss.2012.12.008
http://archimer.ifremer.fr/doc/00124/23529/

Éditeur(s) : Canadian Science Publishing, Nrc Research Press
Résumé : We develop a spatially and seasonally explicit bioeconomic model with three fleet dynamics processes built in endogenously. The model has been applied to the large French trawlers harvesting a medium-depth demersal stock, North Sea saithe (i.e., pollock, Pollachius virens), and a mix of deepwater species over a 10-year period (1999-2008), and the predictions have been contrasted with observations. The best overall fit was achieved where effort allocation was determined to be 80% by traditions and 20% by economic opportunism and where harvest efficiency increased by 8% a year. With this fleet dynamics parameterization, annual trends in fishing effort and profit were well reproduced by the model over the whole time period. Time series of the observed fishing effort by metier were generally well fitted by the model over the period 1999-2003, but less so over 2004-2008. The model also reasonably reproduced the catches by species over most of the time series, except for black scabbardfish (Aphanopus carbo).
Nous développons un modèle bio-économique spatial et saisonnier dans lequel trois processus caractérisant la dynamique des flottilles sont décrits de manière explicite. Ce modèle a été appliqué aux grands chalutiers français exploitant le lieu noir de mer du Nord (Pollachius virens) et une variété d'espèces profondes au cours d'une période de 10 ans (1999–2008), et les prévisions ont été contrastées avec les observations. Le meilleur ajustement est obtenu lorsque l'allocation de l'effort de pêche est déterminée a` hauteur de 80% par les traditions et 20% par l'opportunisme économique, et lorsque l'augmentation de l'efficacité de pêche est d'environ 8% par an. En paramétrant ainsi le module de dynamique des flottilles, les tendances annuelles de l'effort de pêche et du profit sont bien reproduites par le modèle sur l'ensemble de la période. Les variations temporelles de l'effort de pêche par métier sont généralement bien prises en compte sur la période 1999–2003, mais non sur la période 2004–2008. Le modèle ajuste les captures raisonnablement sur la plus grande partie de la période d'étude, pour toutes les espèces sauf le sabre noir (Aphanopus carbo).
Canadian Journal Of Fisheries And Aquatic Sciences (0706-652X) (Canadian Science Publishing, Nrc Research Press), 2013-07 , Vol. 70 , N. 7 , P. 992-1010

Droits : 2013 NRC Research Press
http://archimer.ifremer.fr/doc/00151/26227/24329.pdf
DOI:10.1139/cjfas-2012-0326
http://archimer.ifremer.fr/doc/00151/26227/

Éditeur(s) : Cambridge Univ Press
Résumé : Integrated Multi-Trophic Aquaculture takes advantage of the mutualism between some detritivorous fish and phytoplankton. The fish recycle nutrients by consuming live (and dead) algae and provide the inorganic carbon to fuel the growth of live algae. In the meanwhile, algae purify the water and generate the oxygen required by fishes. Such mechanism stabilizes the functioning of an artificially recycling ecosystem, as exemplified by combining the euryhaline tilapia Sarotherodon melanotheron heudelotii and the unicellular alga Chlorella sp. Feed addition in this ecosystem results in faster fish growth but also in an increase in phytoplankton biomass, which must be limited. In the prototype described here, the algal population control is exerted by herbivorous zooplankton growing in a separate pond connected in parallel to the fish-algae ecosystem. The zooplankton production is then consumed by tilapia, particularly by the fry and juveniles, when water is returned to the main circuit. Chlorella sp. and Brachionus plicatilis are two planktonic species that have spontaneously colonized the brackish water of the prototype, which was set-up in Senegal along the Atlantic Ocean shoreline. In our system, water was entirely recycled and only evaporation was compensated (1.5% volume/day). Sediment, which accumulated in the zooplankton pond, was the only trophic cul-de-sac. The system was temporarily destabilized following an accidental rotifer invasion in the main circuit. This caused Chlorella disappearance and replacement by opportunist algae, not consumed by Brachionus. Following the entire consumption of the Brachionus population by tilapias, Chlorella predominated again. Our artificial ecosystem combining S. m. heudelotii, Chlorella and B. plicatilis thus appeared to be resilient. This farming system was operated over one year with a fish productivity of 1.85 kg/m(2) per year during the cold season (January to April).
Animal (1751-7311) (Cambridge Univ Press), 2013-02 , Vol. 7 , N. 2 , P. 322-329

Droits : The Animal Consortium 2012
http://archimer.ifremer.fr/doc/00118/22955/20945.pdf
DOI:10.1017/S1751731112001279
http://archimer.ifremer.fr/doc/00118/22955/

Éditeur(s) : Oxford Univ Press
Résumé : Spatio-seasonal explicit simulation models can predict the impact of spatial management measures on marine fish populations and fishing activities. As fisheries are complex systems, fisheries simulation models are often complex, with many uncertain parameters. Here, the methodology is provided to deliver fishery diagnostics within an uncertainty context using a complex simulation tool. A sensitivity analysis of the model is performed on model outputs using partial least-squares to identify the most sensitive parameters. The impact of several management measures is then simulated using a statistical simulation design taking into account the uncertainty of the selected sensitive parameters. This approach was applied to the Bay of Biscay anchovy stock using the ISIS-Fish (Integration of Spatial Information for Simulation of Fisheries) model to assess the impact of imposing marine protected areas (MPAs) conditionally on parameter uncertainty. The diagnostic appeared to be highly sensitive to the mortality of larvae and juveniles, growth, and reproduction. The uncertainty of the values of these parameters did not permit any of the simulated MPA designs to be proposed. However, according to anchovy catch and biomass, the simulations allowed the low impact of closure duration to be shown and underscored the utility of protecting such key processes as spawning.
Ices Journal Of Marine Science (1054-3139) (Oxford Univ Press), 2010-07 , Vol. 67 , N. 5 , P. 1063-1075

Droits : 2010 ICES/CIEM. Oxford journals
http://archimer.ifremer.fr/doc/00011/12234/9281.pdf
DOI:10.1093/icesjms/fsq002
http://archimer.ifremer.fr/doc/00011/12234/

Éditeur(s) : Amer Geophysical Union
Résumé : Hydrographic (0-1000 dbar) and direct current measurements (0-600 dbar) along 165-degrees-E (20-degrees-S-10-degrees-N) between January 1984 and July 1991 are used to investigate the mean circulation and its relationships with the distributions of salinity and potential vorticity on isopycnal surfaces. Less well documented mean sections along 142-degrees-E and 137-degrees-E are used to complement the 165-degrees-E analysis. The Equatorial Undercurrent is centered on the equator at 165-degrees-E and on 0.5-degrees-N at 142-degrees-E. No variation in its transport (15.0 x 10(6) m3 s-1) is found between those longitudes. We find indication of the Equatorial Undercurrent at 137-degrees-E-0.75-degrees-N in the geostrophic field. The northern and southern Subsurface Countercurrents are clearly identified by extrema of eastward velocity at 165-degrees-E around 3-degrees-N and 3-degrees-S (250 dbar). No evidence of a southern Subsurface Countercurrent is found at 142-degrees-E. At 137-degrees-E the northern Subsurface Countercurrent is not characterized by a local extrema of eastward velocity: the North Equatorial Countercurrent seems to extend from the surface to 400 dbar with a southward shift of its core. Analysis of the seasonal variability at 165-degrees-E indicates that the Equatorial Undercurrent transport increases by a factor 2 between January (10.7 x 10(6) m3 s-1) and July (21.5 x 10(6) m3 s-1) and the Equatorial Intermediate Current transport is halved (6.3 x 10(6) m3 s-1 in January, 3.5 x 10(6) m3 s-1 in July). hi contrast, the transport of the Subsurface Countercurrents does not vary substantially between those two months. The meridional distributions of salinity and potential vorticity show that the axes of the main eastward currents are associated with strong meridional property gradients, not with property extrema. The eastward currents thus represent a barrier to the northward extension of the high salinity Tropical Water. Relatively weak meridional gradients of salinity and potential vorticity are observed in the westward directed South Equatorial Current and Equatorial Intermediate Current.
Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 1993-12 , Vol. 98 , N. C12 , P. 22495-22520

Droits : 1993 by the American Geophysical Union.
http://archimer.ifremer.fr/doc/00192/30346/29190.pdf
DOI:10.1029/93JC02513
http://archimer.ifremer.fr/doc/00192/30346/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Climate may act on the dispersal and connectivity of marine populations through changes in the oceanic circulation and temperature, and by modifying species' prey and predator distributions. As dispersal and connectivity remain difficult to assess in situ, a first step in studying the effects of climate change can be achieved using biophysical models. To date, only a few biophysical models have been used for this purpose. Here we review these studies and also include results from other recent modelling efforts. We show that increased sea temperature, a major change expected under climate warming, may impact dispersal and connectivity patterns via changes in reproductive phenology (e.g., shift in the spawning season), transport (e.g., reduced pelagic larval duration under faster development rates), mortality (e.g., changes in the exposure to lethal temperatures), and behaviour (e.g.. increased larval swimming speed). Projected changes in circulation are also shown to have large effects on the simulated dispersal and connectivity patterns. Although these biophysical modelling studies are useful preliminary approaches to project the potential effects of climate change, we highlight their current limitations and discuss the way forward, in particular the need for adequate coupled hydrodynamic-biogeochemical simulations using atmospheric forcing from realistic climate change scenarios. (C) 2010 Elsevier Ltd. All rights reserved.
Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2010-10 , Vol. 87 , N. 1-4 , P. 106-113

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00031/14176/11522.pdf
DOI:10.1016/j.pocean.2010.09.005
http://archimer.ifremer.fr/doc/00031/14176/

Éditeur(s) : Elsevier Science Bv
Résumé : Shrimp aquaculture in New Caledonia is subject to seasonal mortalities during grow-out due to highly virulent Vibrio nigripulchritudo (Vn). To understand the mechanisms affecting shrimp resistance and leading to significant mortality, a shrimp ecophysiology and immunology survey was conducted on two farms, the first considered as a "control" farm (HC), the second affected by the disease (DF). Mortality observed during the survey at DF started 50 days after stocking and was typical of this disease. The main observations regarding shrimp were: (a) growth was not affected by the disease and was faster in the DF than in the HC pond; (b) disease did not affect one sex more than the other, or a specific part of the population in terms of weight; (c) the physical condition of shrimp did not specifically allow us to foresee disease outbreak; (d) shrimp at late premolt stage D-2 and early postmolt stage A appeared to be at some points of the mortalities - but not continuously - the most sensitive to disease; (e) physiological, immunological and nutritional parameters of uninfected shrimp in the DF pond were altered, suggesting that environmental stress occurred just before the first mortalities; (f) data suggest that Vn-infected shrimp are more stressed than the presumed healthy shrimp. Combined with pathological and environmental knowledge gained in parallel during this survey, a conceptual model is proposed. Results suggest that an unstable environment induced conditions (i) stressful for the shrimp, increasing their susceptibility to bacterial infections and (ii) favoring the proliferation of the pathogen in the pond. The combination of these two processes could lead to significant mortality.
Aquaculture (0044-8486) (Elsevier Science Bv), 2013-04 , Vol. 388 , P. 105-114

Droits : 2013 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00176/28764/27567.pdf
DOI:10.1016/j.aquaculture.2013.01.010
http://archimer.ifremer.fr/doc/00176/28764/

Éditeur(s) : Université de la Méditerranée
Résumé : This study was supported by the Atlantic working site of the « Programme National d’Océanographie Côtière » (PNOC, PNEC since 1999). The objectives were (1) to check the existence and to understand the mechanisms of winter phytoplankton blooms in the bay of Biscay influenced by the Gironde waters (2) to determine the limiting nutrient of the primary production associated to these blooms and to follow the seasonal evolution of the limiting nutrient, (3) to understand the consequences of this early limitation on the structuration of algal populations in spring. Since phosphorus was supposed to be the major limiting nutrient of algal growth in the Gironde plume, the different forms of the phosphorus cycle as well as the bacterial compartment, central in this cycle, were also studied in term of stocks and fluxes. The sampling strategy consisted in three cruises in 1998, BIOMET 2 (January), BIOMET 3 (beginning of March), PEGASE (June) and six cruises in 1999, PLAGIA 1 to 6 (late February, late April, late May, late June, the middle of July and the beginning of October). Winter algal blooms, essentially diatoms, were actually observed both in the typical waters of the plume (S < 34.5) and at the limit of the plume and adjacent atlantic oceanic waters (S > 34.5) in the successives years 1998 and 1999. These blooms were initiated by the occurrence of short anticyclonic windows in winter, acting on physical processes which dominate the evolution and characteristics of the Gironde plume (runoff, wind direction and speed) and, ultimately, on the evolution of the depth of the mixed layer (haline stratification) and available light (decrease of turbidity). The algal growth was actually phosphorus limited in the typical waters of the plume at the end of the winter bloom, in spring and became nitrogen and phosphorus limited in summer until the first autumn gales restored the nutritive balance. More oceanic waters (S > 34.5) were probably N+P limited from the end of the winter-the beginning of spring to autumn. Phosphorus limitation of winter blooms, associated with girondine unbalanced nutritive supplies (high NO3/PO4 ratios) favoured the development of small cells at the beginning of spring and the later presence of spring blooms (June 1998, late May 1999) composed of pico and nanophytoplankton (nanoflagellates), instead of typical diatom spring blooms for temperate waters. This size reduction of algal communities is strongthened by the competition between phytoplankton and bacteria for the phosphate uptake, bacteria being more competitives at low concentrations and being phosphorus limited sometimes in spring. The decreasing size of algal cells probably acted on the structuration of the whole food web. The study of the different forms of phosphorus displayed the importance of the Dissolved Organic Phosphorus (DOP) pool. The potential biological lability and the capacity of algae and bacteria to use the DOP in spring when phosphate are undetectable was shown by the very high specific activities of alkaline phosphatases and the very rapid cycling of phosphate monoesters. According to the few estimations of actual phosphatasic activity and phosphate assimilation fluxes, the hydrolysis of DOP associated with the coupled assimilation of liberated phosphate would represent 91 to 99 % of the phosphorus fluxes into algal and bacterial cells when phosphate were exhausted. In such conditions DOP could satisfy most of microorganisms phosphorus needs.
Cette thèse s’inscrit dans le cadre du Chantier Atlantique du Programme National d’Océanographie Côtière (PNOC, PNEC depuis 1999). Les objectifs de ce travail étaient (1) de vérifier l’existence et comprendre le déterminisme de blooms phytoplanctoniques hivernaux dans les eaux du Golfe de Gascogne influencées par la Gironde, (2) de préciser le facteur limitant de la production primaire associée à ces blooms et de suivre l’évolution saisonnière de ce facteur et (3) de comprendre les conséquences de cette limitation précoce sur la structuration des populations algales au printemps. Le phosphore étant supposé être le principal élément limitant de la croissance algale dans le panache de la Gironde, les différentes composantes du cycle du phosphore ainsi que le compartiment bactérien, central dans ce cycle, ont été étudiés en terme de stock et de flux. La stratégie d’échantillonnage a consisté en trois campagnes en 1998, BIOMET 2 (janvier), BIOMET 3 (début mars), PEGASE (juin) et six campagnes en 1999, PLAGIA 1 à 6 (fin février, fin avril, fin mai, fin juin, mi-juillet et début octobre). Des efflorescences algales hivernales, constituées essentiellement de diatomées, ont effectivement été observées de façon récurrente dans les eaux typiques du panache (S < 34,5) et à la limite du panache et des eaux océaniques atlantiques adjacentes (S > 34,5) au cours des deux années successives 1998 et 1999. Ces blooms ont été engendrés par l’apparition de courtes fenêtres anticycloniques en période hivernale, ces fenêtres interférant sur les processus physiques qui prévalent sur l’évolution et les caractéristiques du panache de la Gironde (régime des débits, orientation et force du vent) et, de façon ultime, sur l’évolution de la profondeur de la couche de mélange (halostratification) et la disponibilité en lumière (diminution de la turbidité). La croissance algale était limitée par le phosphore dans les eaux typiques du panache à la fin du bloom hivernal, au printemps et devint limitée en azote et en phosphore en période estivale et ceci jusqu’à ce que les premières tempêtes automnales rétablissent l’équilibre nutritif des eaux. Les eaux à caractère plus océanique (S > 34,5) étaient plus probablement limitées par N+P dès la fin de l’hiverdébut du printemps et ce jusqu’à l’automne. La limitation des blooms hivernaux par le phosphore, associée à des apports nutritifs girondins déséquilibrés en phosphate (rapports NO3/PO4 élevés) a favorisé le développement de cellules de petite taille au début du printemps et la présence ultérieure de blooms printaniers (juin 1998, fin mai 1999) composés de pico- et de nanophytoplancton (nanoflagellés), blooms « atypiques » pour des eaux tempérées à cette saison. Cette structuration des communautés algales est renforcée par la compétition entre le phytoplancton et les bactéries pour l’acquisition du phosphate, les bactéries étant plus compétitives aux faibles teneurs en phosphate et pouvant être elles-mêmes limitées par le phosphore à certains moments du printemps. La diminution de taille des cellules algales a probablement une incidence sur la structure de taille de l’ensemble du réseau trophique. L’étude des différentes composantes du phosphore montre l’importance du pool de Phosphore Organique Dissous (POD), sa labilité biologique potentielle et la capacité des communautés algales et bactériennes à utiliser ce pool au printemps quand les phosphates sont indétectables (activités spécifiques des phosphatases alcalines très élevées, recyclage très rapide des monoesters de phosphate). Au vu des quelques estimations de l’activité phosphatasique réelle et des flux d’assimilation de phosphate, l’hydrolyse du POD associée à l’assimilation couplée du phosphate libéré représenterait 91 à 99 % des flux de phosphore vers les cellules algales et bactériennes, quand les phosphates du milieu sont déficients. Dans de telles conditions, le POD pourrait satisfaire l’essentiel des besoins des microorganismes en phosphore.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00013/12463/9298.pdf
http://archimer.ifremer.fr/doc/00013/12463/

Éditeur(s) : Elsevier
Résumé : Vibriosis is a major disease problem in shrimp aquaculture, affecting all developmental stages, from larvae in hatchery tanks to juveniles and broodstock in growout ponds. However, bacterial strains responsible for vibriosis in the successive stages are usually considered to be different, and virulence specificity has been reported both at the species and at the stage levels. The so-called « Syndrome 93 » is a seasonal juvenile vibriosis caused by Vibrio penaeicida which affects Penaeus stylirostris in growout ponds and broodstock tanks in New Caledonia. This pathology does not cause any mortality in hatchery or nursery phases. An experimental infection design using balneation of postlarvae and early juveniles in V. penaeicida suspensions was used to evaluate the developmental stage at which shrimp become sensitive to this vibriosis. We demonstrated that the acquisition of susceptibility to this pathogen is very sudden and correlated with the acquisition of the definitive rostral formula, and from this draw conclusions regarding virulence mechanisms of V. penaeicida in P. stylirostris.
Aquaculture (Elsevier), 1998-12 , Vol. 169 , N. 3-4 , P. 291-296

Droits : 1998 Elsevier Science B.V. All rights reserved
http://archimer.ifremer.fr/doc/1998/publication-383.pdf
DOI:10.1016/S0044-8486(98)00380-9
http://archimer.ifremer.fr/doc/00000/383/

Éditeur(s) : Gauthier-Villars
Résumé : In developing countries, recourse to extensive aquaculture systems based on the exploitation of natural aquatic food webs is currently the subject of considerable interest. In this connection, the construction of artificial reefs (known as Acadja) for the development on substrates of living communities, and the utilization of this new production to enhance fish growth have been evaluated in Cote d'Ivoire. This paper describes the granulometric, chemical and biological transformation of the sedimentary ecosystem as a consequence of this practice. In the artificial habitat, an increase in the sedimentation rate of the mineral fraction (definitive trapping of particle resuspension generated by the waves and induced by the wind) and of the organic fraction (direct and indirect sedimentation of the epiphytic biomass) constitutes the starting point of significant modifications in epibenthic communities. In the Acadja, the meiofauna, dominated by nematodes and copepods, is somewhat less diversified, some groups being absent or poorly represented (turbellarians, gastrotrichs, ostracods). These characteristics were confirmed by a specific study of the nematode assemblages. In fact, the relatively high diversity of the nematode community in the natural lagoon sediment (dominated seasonally by Paraphanolaimus, Anonchus et Daptonema) contrasts with low diversity in the Acadja sediment, where the community is always dominated by Theristus sp. This lower specific diversity generates a reduction of the trophic types. In the Acadja, only the non-selective detritus feeders colonize the fine and organic sediment. These sedimentological and ecological transformations, which affect the entire ''brush park'' (Acadja), induce a strong eutrophication of the benthic ecosystem. Sustainable fish production in such tropical lagoons, in an environment where anaerobic processes dominate (especially sulfate-reduction), calls for strategic spatio-temporal planning to take of account of this progressive eutrophication.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1995 , Vol. 18 , N. 5 , P. 543-555

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00097/20796/18421.pdf
http://archimer.ifremer.fr/doc/00097/20796/

Éditeur(s) : Springer
Résumé : Interannual variability of subtropical sea-surface-height (SSH) anomalies, estimated by satellite and tide-gauge data, is investigated in relation to wintertime daily North-Atlantic weather regimes. Sea-level anomalies can be viewed as proxies for the subtropical gyre intensity because of the intrinsic baroclinic structure of the circulation. Our results show that the strongest correlation between SSH and weather regimes is found with the so-called Atlantic-Ridge (AR) while no significant values are obtained for the other regimes, including those related to the North Atlantic Oscillation (NAO), known as the primary actor of the Atlantic dynamics. Wintertime AR events are characterized by anticyclonic wind anomalies off Europe leading to a northward shift of the climatological wind-stress curl. The latter affects subtropical SSH annual variability by altered Sverdrup balance and ocean Rossby wave dynamics propagating westward from the African coast towards the Caribbean. The use of a simple linear planetary geostrophic model allows to quantify those effects and confirms the primary importance of the winter season to explain the largest part of SSH interannual variability in the Atlantic subtropical gyre. Our results open new perspectives in the comprehension of North-Atlantic Ocean variability emphasizing the role of AR as a driver of interannual variability at least of comparable importance to NAO.
Climate Dynamics (0930-7575) (Springer), 2013-09 , Vol. 41 , N. 5-6 , P. 1159-1171

Droits : Springer-Verlag Berlin Heidelberg 2012
http://archimer.ifremer.fr/doc/00161/27248/25480.pdf
DOI:10.1007/s00382-012-1578-7
http://archimer.ifremer.fr/doc/00161/27248/

Éditeur(s) : Springer
Résumé : The compilation of results obtained on three giant piston cores from the Whittard, Shamrock and Guilcher turbidite levees reveals a high-resolution stratigraphic record for the Bay of Biscay. Due to the abundance of reworked sediments in these sedimentary environments, a specific methodological approach, based on an X-ray-assisted subsampling phase associated with sedimentological, geochemical and micropalaeontological analyses, was implemented. With an accurate chronological framework, this multi-proxy investigation provides observations on the 'Fleuve Manche' palaeoriver and the British-Irish Ice Sheet (BIS) histories over the last 20,000 years. The results obtained highlight the direct influence of the decay of the BIS on the Bay of Biscay deep-sea clastic sedimentation during the last European deglacial phase. During this period, the annual BIS cycle of meltwater seems enough to generate seasonal turbidity currents associated with exceptional sedimentation rates in all the Celtic and Armorican turbidite systems. With very high sedimentation rates, the turbidite levees represent the main deep-sea clastic depositional area. Long coring combined with a very careful subsampling method can provide continuous high-resolution palaeoenvironmental signals.
Geo-Marine Letters (0276-0460) (Springer), 2006-12 , Vol. 26 , N. 6 , P. 317-329

Droits : 2006 Springer Science+Business Media
http://archimer.ifremer.fr/doc/2006/publication-2142.pdf
DOI:10.1007/s00367-006-0048-9
http://archimer.ifremer.fr/doc/00000/2142/

Éditeur(s) : Elsevier
Résumé : The consequences of handling stress (fishing, transfer, eyestalk ablation) on shrimp broodstock are poorly documented. The weakness of farmed shrimp, Litopenaeus stylirostris, during winter is a major problem in New Caledonia, because of seasonal climate (tropical-sub-temperate). The transfer of broodstock in winter from earthen outdoor ponds to indoor maturation tanks in the hatchery (T=20 degrees C, Salinity=35 parts per thousand, fed shrimp) usually leads, after 48 h, to high mortality (up to 70%). Eyestalk ablation to induce ovarian maturation in females leads to further mortality. Starting from a background analysis of physiological disturbances (initial osmoregulatory imbalance) associated with handling stress (Wabete, N., Chim, L., Lernaire, P., Massabuau, J.-C., 2004. Caracterisation de problemes de physiologie respiratoire et d'echanges ioniques associes A la manipulation chez la crevette peneide Litopenaeus stylirostris a 20 degrees C. Styli 2003. Trente ans de crevetticulture en Nouvelle-Caledonie. Ed. Ifremer. Actes Colloq. 38, 75-84.), we developed aprotocol using a soft technology, based on modifications of water salinity, temperature and feeding regime. The aim was to minimize problems of osmoregulatory imbalance and associated mortalities. The protocol we developed, called the LSD OT protocol (Low Salinity and Diet, Optimal Temperature), was first evaluated on sub-adult shrimp (20-25 g) and then applied to broodstock. Survival after transfer and following eyestalk ablation, as well as reproductive achievement (spawning rate, nauplii number) was considerably improved when shrimps were transferred under "physiological comfort" i.e. warmed isosmotic water (26 degrees C and 26 parts per thousand) and unfed for 3 d. This new handling protocol, based on a better control of salinity, temperature and feeding conditions, has been transferred successfully to private hatcheries and already contributes to an increased profitability of New-Caledonian shrimp industry. (c) 2006 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier), 2006-09 , Vol. 260 , N. 1-4 , P. 181-193

Droits : 2006 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-1880.pdf
DOI:10.1016/j.aquaculture.2006.06.041
http://archimer.ifremer.fr/doc/00000/1880/

Résumé : This catalogue deals mainly with common phytoplanktonic species found in the Channel. It is part of a bibliographical survey on pelagos and benthos. The main idea was to gather the largest possible amount of data on the eco-physiology of each species. To do so, studies were conducted in the main marine region where the species had been found and analysed. We focused on several reference ecological studies conducted in the coastal Channel, on the E.D.F. sites, by the C.N.E.X.O., the I.S.T.P.M. and some university laboratories. A great attention was also paid to the studies on seasonal cycles carried out in laboratories in Plymouth, Helgoland and in the Irish zones. (unverified OCR)
Ce catalogue se rapporte essentiellement aux espèces phytoplanctoniques les plus courantes et abondantes en Manche; il s'insère dans une synthèse bibliographique générale concernant le pélagos et le benthos. Nous nous sommes proposés de rassembler le plus grand nombre de données sur l'éco-physiologie de chaque espèce. Pour ce faire, les recherches se sont déroulées dans les principales régions maritimes où l'espèce avait été rencontrée et étudiée. Plus particulièrement, notre attention s'est portée sur les études écologiques de référence effectuées en Manche Littorale sur les sites E.D.F. par le C.N.E.X.O., l'I.S.T.P.M, et les laboratoires universitaires; d'importance aussi, furent les études de cycles saisonniers effectuées au laboratoire de Plymouth, d'Helgoland, et dans les zones irlandaises. OCR NON CONTROLE

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1984/rapport-3701.pdf
http://archimer.ifremer.fr/doc/00000/3701/