|   | 
Détails
   web
Enregistrements
Auteur Ternon, J.-F.; Bach, P.; Barlow, R.; Huggett, J.; Jaquemet, S.; Marsac, F.; Ménard, F.; Penven, P.; Potier, M.; Roberts, M.J.
Titre The Mozambique Channel : from physics to upper trophic levels Type Article scientifique
Année 2014 Publication Revue Abrégée Deep-Sea Research Part II.Topical Studies in Oceanography
Volume 100 Numéro No spécial Pages 1-9
Mots-Clés Biological production; Mesoscale circulation; Mozambique Channel; Multi-disciplinary approach; Physical-biological coupling
Résumé A multidisciplinary programme, MESOBIO (Influence of mesoscale dynamics on biological productivity at multiple trophic levels in the Mozambique Channel) was undertaken in the Mozambique Channel within the framework of a scientific partnership between France and South Africa. MESOBIO focused on the signature of the highly energetic eddy dynamics in the Mozambique Channel. The Channel, which is known to be one of the most turbulent areas in the world ocean, has a great diversity of marine organisms and is the site of active pelagic fisheries. MESOBIO was mostly based on observations at sea during 12 multidisciplinary cruises between 2002 and 2010. Hydrographic measurements, sampling of biological organisms ranging from phytoplankton to top predators, and experiments on primary production and energy transfer through the food web, were conducted onboard various research vessels. The data were analysed in relation to eddy field characteristics for the periods of the cruises, including seasonal or inter-annual variability in mesoscale activity. A modelling approach was also developed within MESOBIO for both the circulation in the Channel and the biogeochemical response to eddy forcing. This paper introduces the suite of articles on the MESOBIO investigations by summarizing background knowledge for the different disciplines and the key issues that were addressed within the programme.
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur Barlow, R.; Marsac, F.; Ternon, J.-F.; Roberts, M.
Langue Langue du Résumé Titre Original (up)
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0967-0645 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 371
Lien permanent pour cet enregistrement
 

 
Auteur BECHELER, R.; BENKARA, E.; MOALIC, Y.; HILY, C.; ARNAUD-HAOND, S.
Titre Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring Type Article scientifique
Année 2014 Publication Revue Abrégée Heredity
Volume 112 Numéro 2 Pages 114-121
Mots-Clés clonality; Seagrass; spatio-temporal genetic structure; Zostera marina
Résumé Theoretically, the dynamics of clonal and genetic diversities of clonal plant populations are strongly influenced by the competition among clones and rate of seedling recruitment, but little empirical assessment has been made of such dynamics through temporal genetic surveys. We aimed to quantify 3 years of evolution in the clonal and genetic composition of Zostera marina meadows, comparing parameters describing clonal architecture and genetic diversity at nine microsatellite markers. Variations in clonal structure revealed a decrease in the evenness of ramet distribution among genets. This illustrates the increasing dominance of some clonal lineages (multilocus lineages, MLLs) in populations. Despite the persistence of these MLLs over time, genetic differentiation was much stronger in time than in space, at the local scale. Contrastingly with the short-term evolution of clonal architecture, the patterns of genetic structure and genetic diversity sensu stricto (that is, heterozygosity and allelic richness) were stable in time. These results suggest the coexistence of (i) a fine grained (at the scale of a 20 x 30 m quadrat) stable core of persistent genets originating from an initial seedling recruitment and developing spatial dominance through clonal elongation; and (ii) a local (at the scale of the meadow) pool of transient genets subjected to annual turnover. This simultaneous occurrence of initial and repeated recruitment strategies highlights the different spatial scales at which distinct evolutionary drivers and mating systems (clonal competition, clonal growth, propagule dispersal and so on) operate to shape the dynamics of populations and the evolution of polymorphism in space and time.
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original (up)
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0018-067x ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1139
Lien permanent pour cet enregistrement
 

 
Auteur Travers-Trolet, M.; Shin, Y.-J.; Shannon, L.J.; Moloney, C.L.; Field, J.G.
Titre Combined fishing and climate forcing in the southern Benguela upwelling ecosystem : an end-to-end modelling approach reveals dampened effects Type Article scientifique
Année 2014 Publication Revue Abrégée Plos One
Volume 9 Numéro 4 Pages
Mots-Clés
Résumé The effects of climate and fishing on marine ecosystems have usually been studied separately, but their interactions make ecosystem dynamics difficult to understand and predict. Of particular interest to management, the potential synergism or antagonism between fishing pressure and climate forcing is analysed in this paper, using an end-to-end ecosystem model of the southern Benguela ecosystem, built from coupling hydrodynamic, biogeochemical and multispecies fish models (ROMS-N(2)P(2)Z(2)D(2)-OSMOSE). Scenarios of different intensities of upwelling-favourable wind stress combined with scenarios of fishing top-predator fish were tested. Analyses of isolated drivers show that the bottom-up effect of the climate forcing propagates up the food chain whereas the top-down effect of fishing cascades down to zooplankton in unfavourable environmental conditions but dampens before it reaches phytoplankton. When considering both climate and fishing drivers together, it appears that top-down control dominates the link between top-predator fish and forage fish, whereas interactions between the lower trophic levels are dominated by bottom-up control. The forage fish functional group appears to be a central component of this ecosystem, being the meeting point of two opposite trophic controls. The set of combined scenarios shows that fishing pressure and upwelling-favourable wind stress have mostly dampened effects on fish populations, compared to predictions from the separate effects of the stressors. Dampened effects result in biomass accumulation at the top predator fish level but a depletion of biomass at the forage fish level. This should draw our attention to the evolution of this functional group, which appears as both structurally important in the trophic functioning of the ecosystem, and very sensitive to climate and fishing pressures. In particular, diagnoses considering fishing pressure only might be more optimistic than those that consider combined effects of fishing and environmental variability.
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original (up)
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1932-6203 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 372
Lien permanent pour cet enregistrement
 

 
Auteur LELIEVRE, S.; VAZ, S.; Martin, C.S.; LOOTS, C.
Titre Delineating recurrent fish spawning habitats in the North Sea Type Article scientifique
Année 2014 Publication Revue Abrégée Journal Of Sea Research
Volume 91 Numéro Pages 1-14
Mots-Clés Egg Distribution; Glm; Habitat Modelling; North sea; Spawning Grounds; temporal variability
Résumé The functional value of spawning habitats makes them critically important for the completion of fish life cycles and spawning grounds are now considered to be “essential habitats”. Inter-annual fluctuations in spawning ground distributions of dab (Limanda Limanda), plaice (Pleuronectes platessa), cod (Gadus morhua) and whiting (Merlangius merlangus) were investigated in the southern North Sea and eastern English Channel, from 2006 to 2009. The preferential spawning habitats of these species were modelled using generalised linear models, with egg distribution being used as proxy of spawners’ location. Egg spatial and temporal distributions were explored based on six environmental variables: sea surface temperature and salinity, chlorophyll a concentration, depth, bedstress and seabed sediment types. In most cases, egg density was found to be strongly related to these environmental variables. Egg densities were positively correlated with shallow to intermediate depths having low temperature and relatively high salinity. Habitat models were used to map annual, i.e. 2006 to 2009, winter spatial distributions of eggs, for each species separately. Then, annual maps were combined to explore the spatial variability of each species' spawning grounds, and define recurrent, occasional, rare and unfavourable spawning areas. The recurrent spawning grounds of all four species were located in the south-eastern part of the study area, mainly along the Dutch and German coasts. This study contributes knowledge necessary to the spatial management of fisheries resources in the area, and may also be used to identify marine areas with particular habitat features that need to be preserved.
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original (up)
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1385-1101 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 373
Lien permanent pour cet enregistrement
 

 
Auteur BRIND'AMOUR, A.; LAFFARGUE, P.; MORIN, J.; VAZ, S.; FOVEAU, A.; LE BRIS, H.
Titre Morphospecies and taxonomic sufficiency of benthic megafauna in scientific bottom trawl surveys Type Article scientifique
Année 2014 Publication Revue Abrégée Continental Shelf Research
Volume 72 Numéro Pages 1-9
Mots-Clés Bay of Biscay; Benthic descriptor; Bottom trawl surveys; English Channel; North sea; Taxonomic sufficiency
Résumé Scientific fisheries surveys routinely identify a large diversity of commercial and non-commercial benthic megainvertebrates that could provide useful information for Marine Strategy Framework Directive (MSFD) descriptors. Species is obviously the basic taxonomic level to which most ecological studies and theories refer. Identification at this level of organization is indeed always preferred over any other taxonomic level. Nevertheless, aggregation of species to higher taxonomic levels may be unavoidable sometimes, since errors of identification are known or suspected to occur in many surveys. Using analyses of taxonomic sufficiency (identification of organisms at various taxonomic resolutions) and groups of morphospecies (taxa identified easily by non-experts on the basis of evident morphological traits), this study aims to quantify the loss of ecological information incurred by partial identification of benthic megafauna in bottom trawl surveys in order to put such data to good use. The analyses were conducted on five scientific surveys representing a large range of geographical areas (from 150 km2 to 150 000 km2) and environmental conditions. Results show that genus, family and, particularly, morphospecies are good surrogates for species identification in community analyses. We suggest that bottom trawl surveys can provide reliable megafauna data that may usefully complete those obtained by grab surveys. The use of morphospecies could lead to new strategies, combining different datasets to provide indicators for MSFD descriptors (e.g. D6).
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original (up)
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0278-4343 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1141
Lien permanent pour cet enregistrement