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Auteur BRIND'AMOUR, A.; LAFFARGUE, P.; MORIN, J.; VAZ, S.; FOVEAU, A.; LE BRIS, H. url  openurl
  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).  
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  ISSN 0278-4343 ISBN Médium  
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Auteur BECHELER, R.; BENKARA, E.; MOALIC, Y.; HILY, C.; ARNAUD-HAOND, S. url  openurl
  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.  
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  ISSN 0018-067x ISBN Médium  
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Auteur ARNAUD-HAOND, S.; MOALIC, Y.; HERNANDEZ-GARCIA, E.; EGUILUZ, V.M.; ALBERTO, F.; SERRAO, E.A.; DUARTE, C.M. url  openurl
  Titre Disentangling the Influence of Mutation and Migration in Clonal Seagrasses Using the Genetic Diversity Spectrum for Microsatellites Type Article scientifique
  Année 2014 Publication Revue Abrégée Journal Of Heredity  
  Volume 105 Numéro 4 Pages 532-541  
  Mots-Clés clonality; genetic divergence; Genetic Diversity Spectrum; microsatellites; Seagrass; stepwise mutation  
  Résumé The recurrent lack of isolation by distance reported at regional scale in seagrass species was recently suggested to stem from stochastic events of large-scale dispersal. We explored the usefulness of phylogenetic information contained in microsatellite loci to test this hypothesis by using the Genetic Diversity Spectrum (GDS) on databases containing, respectively, 7 and 9 microsatellites genotypes for 1541 sampling units of Posidonia oceanica and 1647 of Cymodocea nodosa. The simultaneous increase of microsatellite and geographic distances that emerges reveals a coherent pattern of isolation by distance in contrast to the chaotic pattern previously described using allele frequencies, in particular, for the long-lived P. oceanica. These results suggest that the lack of isolation by distance, rather than the resulting from rare events of large-scale dispersal, reflects at least for some species a stronger influence of mutation over migration at the scale of the distribution range. The global distribution of genetic polymorphism may, therefore, result predominantly from ancient events of step-by-step (re)colonization followed by local recruitment and clonal growth, rather than contemporary gene flow. The analysis of GDS appears useful to unravel the evolutionary forces influencing the dynamics and evolution at distinct temporal and spatial scales by accounting for phylogenetic information borne by microsatellites, under an appropriate mutation model. This finding adds nuance to the generalization of the influence of large-scale dispersal on the dynamics of seagrasses.  
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  ISSN 0022-1503 ISBN Médium  
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Auteur MAHE, K.; VILLANUEVA, C.-M.; VAZ, S.; COPPIN, F.; KOUBBI, P.; CARPENTIER, A. url  openurl
  Titre Morphological variability of the shape of striped red mullet Mullus surmuletus in relation to stock discrimination between the Bay of Biscay and the eastern English Channel Type Article scientifique
  Année 2014 Publication Revue Abrégée Journal Of Fish Biology  
  Volume 84 Numéro 4 Pages 1063-1073  
  Mots-Clés fish body shape; head morphology; morphometric analysis; stock identification; Truss model  
  Résumé Striped red mullet Mullus surmuletus L. 1758 is an economically important species in the Mediterranean Sea and in the northern Atlantic Ocean, where it is exploited from the Bay of Biscay to the southern North Sea (ICES, 2010). In Atlantic waters, there are two main areas where this species is caught, the Bay of Biscay and the eastern English Channel. This species was initially exploited by the Spanish fleets along the Spanish coast inside the Bay of Biscay. Originally considered as valuable by-catch (Marchal, 2008), the growing exploitation ofM. surmuletus and a conspicuous increase in landings in the English Channel and the southern North Sea by French, English and Dutch fleets have been observed from the 1990s onwards. This was attributed to an increase in the migratory distribution and abundance of this species in these areas, which is largely heightened by the decline of traditionally targeted species and the trend for sea water warming (Poulard&Blanchard, 2005; Marchal, 2008; ICES, 2010).  
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  ISSN 0022-1112 ISBN Médium  
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Auteur BAUER, R.; Graewe, U.; Stepputtis, D.; Zimmermann, C.; Hammer, C. url  openurl
  Titre Identifying the location and importance of spawning sites of Western Baltic herring using a particle backtracking model Type Article scientifique
  Année 2014 Publication Revue Abrégée Ices Journal Of Marine Science  
  Volume 71 Numéro 3 Pages 499-509  
  Mots-Clés backtracking; Baltic Sea; Clupea harengus; hatching sites; lagoon; larval transport; spring spawning  
  Résumé The recruitment success of some herring stocks fluctuates strongly, and apparently, success is often already determined during the early life stages, i.e. before metamorphosis. In studying the survival of early life stages and its affecting factors, particularly those during the egg stage, it is crucial to examine the processes at the spawning sites, which often cannot be explored directly. A recent decline in the recruitment of Western Baltic spring-spawning herring (WBSSH) increases the urgency of filling the knowledge gap for this stock, especially because one bottleneck in the recruitment seems to occur before hatching. We examined the successful 20032009 spawning sites of WBSSH in the main spawning ground, the Greifswalder Bodden lagoon. Instead of using common techniques such as diving or underwater videography, which are usually unsuitable for mapping large areas, we applied a model approach. We tracked herring larvae at length 610 mm, recorded by larval surveys during MarchJune of the respective years, back to their hatching sites using a Lagrangian particle backtracking model. We compared the spawning areas identified by the model with the results of earlier field studies; however, we also analysed variations between years, larval length groups, and different applied growth models, which are needed to define hatch-dates. Although spawning sites could not be identified with high precision because of the strong diffusion in the area studied, results indicate that larvae up to 10 mm length are caught near their hatching sites. However, the location of successful spawning sites varied largely between years, with the main hatching sites situated in the Strelasund and the eastern entrance of the lagoon. This may reflect variations in spawning-site selection or quality. A better knowledge of the locations and relative importance of, and the processes occurring on, the different spawning sites will provide an important contribution to the sustainable management of this commercially valuable herring stock.  
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