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Auteur (up) Grüss, A.; Schirripa, M.J.; Chagaris, D.; Drexler, M.; Simons, J.; Verley, P.; Shin, Y.-J.; Karnauskas, M.; Oliveros-Ramos, R.; Ainsworth, C.H. url  doi
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  Titre Evaluation of the trophic structure of the West Florida Shelf in the 2000s using the ecosystem model OSMOSE Type Article scientifique
  Année 2015 Publication Revue Abrégée Journal of Marine Systems  
  Volume 144 Numéro Pages 30-47  
  Mots-Clés Gag grouper; Marine ecosystem modeling; Natural mortality; resource management; trophic structure; West Florida Shelf  
  Résumé We applied the individual-based, multi-species OSMOSE modeling approach to the West Florida Shelf, with the intent to inform ecosystem-based management (EBM) in this region. Our model, referred to as ‘OSMOSE-WFS’, explicitly considers both pelagic-demersal and benthic high trophic level (HTL) groups of fish and invertebrate species, and is forced by the biomass of low trophic level groups of species (plankton and benthos). We present a steady-state version of the OSMOSE-WFS model describing trophic interactions in the West Florida Shelf in the 2000s. OSMOSE-WFS was calibrated using a recently developed evolutionary algorithm that allowed simulated biomasses of HTL groups to match observed biomasses over the period 2005–2009. The validity of OSMOSE-WFS was then evaluated by comparing simulated diets to observed ones, and the simulated trophic levels to those in an Ecopath model of the West Florida Shelf (WFS Reef fish Ecopath). Finally, OSMOSE-WFS was used to explore the trophic structure of the West Florida Shelf in the 2000s and estimate size-specific natural mortality rates for a socio-economically important species, gag grouper (Mycteroperca microlepis). OSMOSE-WFS outputs were in full agreement with observations as to the body size and ecological niche of prey of the different HTL groups, and to a lesser extent in agreement with the observed species composition of the diet of HTL groups. OSMOSE-WFS and WFS Reef fish Ecopath concurred on the magnitude of the instantaneous natural mortality of the different life stages of gag grouper over the period 2005–2009, but not always on the main causes of natural mortality. The model evaluations conducted here provides a strong basis for ongoing work exploring fishing and environmental scenarios so as to inform EBM. From simple size-based predation rules, we were indeed able to capture the complexity of trophic interactions in the West Florida Shelf, and to identify the predators, prey and competitors of socio-economically important species as well as pivotal prey species of the ecosystem.  
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  ISSN 0924-7963 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1253  
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Auteur (up) Grüss, A.; Schirripa, M.J.; Chagaris, D.; Velez, L.; Shin, Y.-J.; Verley, P.; Oliveros-Ramos, R.; Ainsworth, C.H. url  doi
openurl 
  Titre Estimating natural mortality rates and simulating fishing scenarios for Gulf of Mexico red grouper (Epinephelus morio) using the ecosystem model OSMOSE-WFS Type Article scientifique
  Année 2016 Publication Revue Abrégée Journal of Marine Systems  
  Volume 154, Part B Numéro Pages 264-279  
  Mots-Clés Fishing scenarios; Gulf of Mexico; Marine ecosystem modeling; Natural mortality; Red grouper; West Florida Shelf  
  Résumé The ecosystem model OSMOSE-WFS was employed to evaluate natural mortality rates and fishing scenarios for Gulf of Mexico (GOM) red grouper (Epinephelus morio). OSMOSE-WFS represents major high trophic level (HTL) groups of species of the West Florida Shelf, is forced by the biomass of plankton and benthos groups, and has a monthly time step. The present application of the model uses a recently developed ‘stochastic mortality algorithm’ to resolve the mortality processes of HTL groups. OSMOSE-WFS predictions suggest that the natural mortality rate of juveniles of GOM red grouper is high and essentially due to predation, while the bulk of the natural mortality of adult red grouper results from causes not represented in OSMOSE-WFS such as, presumably, red tides. These results were communicated to GOM red grouper stock assessments. Moreover, OSMOSE-WFS indicate that altering the fishing mortality of GOM red grouper may have no global impact on the biomass of the major prey of red grouper, due to the high complexity and high redundancy of the modeled system. By contrast, altering the fishing mortality of GOM red grouper may have a large impact on the biomass of its major competitors. Increasing the fishing mortality of red grouper would increase the biomass of major competitors, due to reduced competition for food. Conversely, decreasing the fishing mortality of red grouper would diminish the biomass of major competitors, due to increased predation pressure on the juveniles of the major competitors by red grouper. The fishing scenarios that we evaluated may have slightly different impacts in the real world, due to some discrepancies between the diets of red grouper and its major competitors predicted by OSMOSE-WFS and the observed ones. Modifications in OSMOSE-WFS are suggested to reduce these discrepancies.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0924-7963 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1500  
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Auteur (up) Guiet, J.; Poggiale, J.-C.; Maury, O. url  doi
openurl 
  Titre Modelling the community size-spectrum: recent developments and new directions Type Article scientifique
  Année 2016 Publication Revue Abrégée Ecological Modelling  
  Volume 337 Numéro Pages 4-14  
  Mots-Clés climate change; Community size-spectrum; ecosystem-based management; end-to-end model; Marine ecosystem model; Trait-based model  
  Résumé The regularity of the community size-spectrum, i.e., the fact that the total ecosystem biomass contained in logarithmically equal body size intervals remains constant, is a striking characteristic of marine ecosystems. Community size-spectrum models exploit this feature to represent marine ecosystems with two measures: the slope and the intercept (height) of the community spectrum. Size-spectrum models have gain popularity over time to model the properties of fish communities, whether to investigate the impact of fishing, or embedded into end-to-end models to investigate the impact of climate. We review the main features and state of the art developments in the domain of continuous size-spectrum models. The community spectrum emerges from a balance between size-selective predation, growth and biomass dissipation. Further to these basic components, reproduction and various causes of mortality have been introduced in recent studies to increase the model's realism or simply close the mass budget of the spectrum. These different processes affect the stability of the spectrum and affect the predictions of the size-spectrum models. A few models have also introduced a representation of life-history traits in the community size-spectrum. This allows accounting for the diversity of energy pathways in food webs and for the fact that metabolism is both size- and species-specific. The community-level metabolism therefore depends on the species composition of the community. The size-spectrum's regularity at the community level can serve as a conceptual basis for building theories of marine ecosystems’ functioning. It is also used as indicator of anthropogenic and natural disturbances. The mechanistic nature of size-spectrum models as well as their simple and aggregated representation of complex systems makes them good candidates as a strategic management tool. For instance, for testing the impact of different fishing management actions or for projecting marine ecosystem's states under various climate change scenarios.  
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  ISSN 0304-3800 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1586  
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Auteur (up) Guilhaumon, F.; Albouy, C.; Claudet, J.; Velez, L.; Ben Rais Lasram, F.; Tomasini, J.-A.; Douzery, E.J.P.; Meynard, C.N.; Mouquet, N.; Troussellier, M.; Araújo, M.B.; Mouillot, D. url  doi
openurl 
  Titre Representing taxonomic, phylogenetic and functional diversity: new challenges for Mediterranean marine-protected areas Type Article scientifique
  Année 2015 Publication Revue Abrégée Diversity Distrib.  
  Volume 21 Numéro 2 Pages 175-187  
  Mots-Clés Functional diversity; Gap analysis; marine-protected area; Mediterranean fishes; phylogenetic diversity; reserves; taxonomic diversity  
  Résumé Aim To assess gaps in the representation of taxonomic, phylogenetic and functional diversity among coastal fishes in Mediterranean marine-protected areas (MPAs). Location Mediterranean Sea. Methods We first assessed gaps in the taxonomic representation of the 340 coastal fish species in Mediterranean MPAs, with representation targets (the species range proportion to be covered by MPAs) set to be inversely proportional to species' range sizes. We then asked whether MPAs favoured representation of phylogenetically and functionally more distinct species or whether there was a tendency to favour less distinctive ones. We finally evaluated the overall conservation effectiveness of the MPAs using a metric that integrates species' phylogenetic and functional relationships and targets achievement. The effectiveness of the MPA system at protecting biodiversity was assessed by comparison of its achievements against a null model obtained by siting current MPAs at random over the study area. Results Among the coastal fish species analysed, 16 species were not covered by any MPA. All the remaining species only partially achieved the pre-defined representation target. The current MPA system missed fewer species than expected from siting MPAs at random. However, c. 70% of the species did not achieve better protection in the current MPAs than expected from siting MPAs at random. Functional and evolutionary distinctiveness were weakly correlated with target achievement. The observed coverage of taxonomic, phylogenetic and functional diversity was not different or lower than expected from siting MPAs at random. Main conclusions The Mediterranean MPA system falls short in meeting conservation targets for coastal fish taxonomic diversity, phylogenetic diversity and functional diversity. Mediterranean MPAs do not encompass more biodiversity than expected by chance. This study reveals multiple ongoing challenges and calls for regional collaboration for the extension of the Mediterranean system of MPAs to meet international commitments and reduce the ongoing loss of marine biodiversity.  
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  Langue en Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1472-4642 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1254  
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Auteur (up) Hadjadji, I.; Masseret, E.; Plisson, B.; Laabir, M.; Cecchi, P.; Collos, Y. url  openurl
  Titre Clonal variation in physiological parameters of Alexandrium tamarense: implications for biological invasions and maintenance Type Article scientifique
  Année 2012 Publication Revue Abrégée Cah. Biol. Mar.  
  Volume 53 Numéro 3 Pages 357-363  
  Mots-Clés Alexandrium tamarense; Fitness; Growth rate; Humic acid; Intraspecific variability; Lag phase; blooms; catenella; complex dinophyceae; dinoflagellate; dinophyceae; growth; humic substances; marine-phytoplankton; southern france; thau lagoon; urea uptake  
  Résumé The study of the intraspecific variability is a crucial step for understanding the successful establishment and maintenance of invasive species. Alexandrium tamarense strains isolated in spring 2007 from a single bloom in Thau lagoon have been grown on three different media (ESNW based on natural seawater, and the artificial media, ESAW, ESAW+HA). A large diversity in the ability of strains to grow on these media was found. Irrespective of medium composition, growth curves followed three models: (1) a classical shape, (2) a population crash followed in some cases (3) by growth recovery. Some strains were able to show significant growth in an environment completely artificial (ESAW). ANOVA indicated a significant difference between groups in growth rates allowing the distinction of contrasted categories among the strains studied in ESNW medium. These statistical tests also indicated the presence of distinct groups among the strains grown in the ESAW as well as for those on ESAW+HA medium. Lag phases were extremely variable between strains in all environments, suggesting a high variability of adaptation to the environment. The results revealed that wide fitness variations were exhibited by diverse conspecific A. tamarense individuals co-existing during a bloom.  
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  Langue English Langue du Résumé Titre Original  
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  ISSN 0007-9723 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 473  
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