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Auteur Maury, O.; Poggiale, J.-C. url  openurl
  Titre From individuals to populations to communities: A dynamic energy budget model of marine ecosystem size-spectrum including life history diversity Type Article scientifique
  Année 2013 Publication Revue Abrégée Journal of Theoretical Biology  
  Volume 324 Numéro Pages 52-71  
  Mots-Clés biodiversity; Dynamic Energy Budget theory; predation; Schooling; Size spectrum  
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  ISSN 0022-5193 ISBN Médium  
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  Notes <p>\textbackslashtextlessp\textbackslashtextgreaterIndividual metabolism, predator–prey relationships, and the role of biodiversity are major factors underlying the dynamics of food webs and their response to environmental variability. Despite their crucial, complementary and interacting influences, they are usually not considered simultaneously in current marine ecosystem models. In an attempt to fill this gap and determine if these factors and their interaction are sufficient to allow realistic community structure and dynamics to emerge, we formulate a mathematical model of the size-structured dynamics of marine communities which integrates mechanistically individual, population and community levels. The model represents the transfer of energy generated in both time and size by an infinite number of interacting fish species spanning from very small to very large species. It is based on standard individual level assumptions of the Dynamic Energy Budget theory (DEB) as well as important ecological processes such as opportunistic size-based predation and competition for food. Resting on the inter-specific body-size scaling relationships of the DEB theory, the diversity of life-history traits (i.e. biodiversity) is explicitly integrated. The stationary solutions of the model as well as the transient solutions arising when environmental signals (e.g. variability of primary production and temperature) propagate through the ecosystem are studied using numerical simulations. It is shown that in the absence of density-dependent feedback processes, the model exhibits unstable oscillations. Density-dependent schooling probability and schooling-dependent predatory and disease mortalities are proposed to be important stabilizing factors allowing stationary solutions to be reached. At the community level, the shape and slope of the obtained quasi-linear stationary spectrum matches well with empirical studies. When oscillations of primary production are simulated, the model predicts that the variability propagates along the spectrum in a given frequency-dependent size range before decreasing for larger sizes. At the species level, the simulations show that small and large species dominate the community successively (small species being more abundant at small sizes and large species being more abundant at large sizes) and that the total biomass of a species decreases with its maximal size which again corroborates empirical studies. Our results indicate that the simultaneous consideration of individual growth and reproduction, size-structured trophic interactions, the diversity of life-history traits and a density-dependent stabilizing process allow realistic community structure and dynamics to emerge without any arbitrary prescription. As a logical consequence of our model construction and a basis for future studies, we define the function Φ as the relative contribution of each species to the total biomass of the ecosystem, for any given size. We argue that this function is a measure of the functional role of biodiversity characterizing the impact of the structure of the community (its species composition) on its function (the relative proportions of losses, dissipation and biological work).\textbackslashtextless/p\textbackslashtextgreater</p> Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection (up) 245  
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Auteur Katsanevakis, S.; Coll, M.; Piroddi, C.; Steenbeek, J.; Ben Rais Lasram, F.; Zenetos, A.; Cardoso, A.C. url  doi
openurl 
  Titre Invading the Mediterranean Sea: biodiversity patterns shaped by human activities Type Article scientifique
  Année 2014 Publication Revue Abrégée Front. Mar. Sci  
  Volume 1 Numéro Pages  
  Mots-Clés alien species; Aquaculture; biodiversity patterns; biological invasions; Lessepsian migrants; pathways; shipping  
  Résumé Human activities, such as shipping, aquaculture, and the opening of the Suez Canal, have led to the introduction of nearly 1000 alien species into the Mediterranean Sea. We investigated how human activities, by providing pathways for the introduction of alien species, may shape the biodiversity patterns in the Mediterranean Sea. Richness of Red Sea species introduced through the Suez Canal (Lessepsian species) is very high along the eastern Mediterranean coastline, reaching a maximum of 129 species per 100 km2, and declines toward the north and west. The distribution of species introduced by shipping is strikingly different, with several hotspot areas occurring throughout the Mediterranean basin. Two main hotspots for aquaculture-introduced species are observed (the Thau and Venice lagoons). Certain taxonomic groups were mostly introduced through specific pathways—fish through the Suez Canal, macrophytes by aquaculture, and invertebrates through the Suez Canal and by shipping. Hence, the local taxonomic identity of the alien species was greatly dependent on the dominant maritime activities/interventions and the related pathways of introduction. The composition of alien species differs among Mediterranean ecoregions; such differences are greater for Lessepsian and aquaculture-introduced species. The spatial pattern of native species biodiversity differs from that of alien species: the overall richness of native species declines from the north-western to the south-eastern regions, while the opposite trend is observed for alien species. The biodiversity of the Mediterranean Sea is changing, and further research is needed to better understand how the new biodiversity patterns shaped by human activities will affect the Mediterranean food webs, ecosystem functioning, and the provision of ecosystem services.  
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Auteur Potier, M.; Bach, P.; Ménard, F.; Marsac, F. url  doi
openurl 
  Titre Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel Type Article scientifique
  Année 2014 Publication Revue Abrégée Deep-Sea Research Part II.Topical Studies in Oceanography  
  Volume 100 Numéro No spécial Pages 184-199  
  Mots-Clés Biodiversity; Mid-water trawl; Mozambique Channel; Oceanic eddies; Pelagic longline; Stomach contents  
  Résumé We investigated the diversity and distribution of two communities, micronekton organisms and large predatory fishes, sampled in mesoscale features of the Mozambique Channel from 2003 to 2009, by combining mid-water trawls, stomach contents of fish predators and instrumented longline fishing surveys. The highest species richness for assemblages was found in divergences and fronts rather than in the core of eddies. Despite an unbalanced scheme, diversity indices did not differ significantly between cyclonic and anticyclonic eddies, divergences and fronts. We found that eddies and associated physical cues did not substantially affect the distribution of micronektonic species which are mainly driven by the diel vertical migration pattern. Top predators exhibited a more complex response. Swordfish (Xiphias gladius) associated better with mesoscale features than tunas, with a clear preference for divergences which is consistent with the diel vertical migrations and occurrence of its main prey, the flying squids Sthenoteuthis oualaniensis (Ommastrephidae). On the other hand, the probability of presence of yellowfin tuna was not tied to any specific eddy structure. However, the highest values of positive yellowfin CPUEs were associated with low horizontal gradients of sea-level anomalies. We also showed a non-linear response of positive yellowfin CPUEs with respect to the depth of the minimal oxygen content. The larger the distance between the hooks and the minimal oxygen layer, towards the surface or at greater depths, the higher the CPUE, highlighting that yellowfin congregated in well-oxygenated waters. Micronekton sampled by mid-water trawls and stomach contents exhibited different species composition. The highly mobile organisms were not caught by trawling whereas they remain accessible to predators. The combination of stomach contents and mid-water trawls undoubtedly improved our understanding of the micronekton assemblage distribution. Our results provide some evidence that mesoscale features in the Mozambique Channel do not strongly affect the distribution of the mid-trophic level organisms such as micronekton and most of the large predatory fishes, and hypotheses are proposed to support this result.  
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  Editeur Lieu de Publication Éditeur Barlow, R.; Marsac, F.; Ternon, J.-F.; Roberts, M.  
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  ISSN 0967-0645 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection (up) 369  
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Auteur Tedesco, P.A.; Oberdorff, T.; Cornu, J.-F.; Beauchard, O.; Brosse, S.; Dürr, H.H.; Grenouillet, G.; Leprieur, F.; Tisseuil, C.; Zaiss, R.; Hugueny, B. url  doi
openurl 
  Titre A scenario for impacts of water availability loss due to climate change on riverine fish extinction rates Type Article scientifique
  Année 2013 Publication Revue Abrégée Journal of Applied Ecology  
  Volume 50 Numéro 5 Pages 1105-1115  
  Mots-Clés aridity index; current anthropogenic threats; diversity loss; drainage area; freshwater fish diversity; habitat availability; time to extinction  
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  ISSN 1365-2664 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (up) 405  
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Auteur Escalas, A.; Bouvier, T.; Mouchet, M.A.; Leprieur, F.; Bouvier, C.; Troussellier, M.; Mouillot, D. url  doi
openurl 
  Titre A unifying quantitative framework for exploring the multiple facets of microbial biodiversity across diverse scales Type Article scientifique
  Année 2013 Publication Revue Abrégée Environmental microbiology  
  Volume 15 Numéro 10 Pages 2642-2657  
  Mots-Clés Microbial communities; Rao quadratic entropy; metagenomic; microbial biodiversity; molecular fingerprint; β diversity  
  Résumé Recent developments of molecular tools have revolutionized our knowledge of microbial biodiversity by allowing detailed exploration of its different facets and generating unprecedented amount of data. One key issue with such large datasets is the development of diversity measures that cope with different data outputs and allow comparison of biodiversity across different scales. Diversity has indeed three components: local (alpha), regional (gamma) and the overall difference between local communities (beta). Current measures of microbial diversity, derived from several approaches, provide complementary but different views. They only capture the beta component of diversity, compare communities in a pairwise way, consider all species as equivalent or lack a mathematically explicit relationship among the alpha, beta and gamma components. We propose a unified quantitative framework based on the Rao quadratic entropy, to obtain an additive decomposition of diversity (gamma = alpha + beta), so the three components can be compared, and that integrate the relationship (phylogenetic or functional) among Microbial Diversity Units that compose a microbial community. We show how this framework is adapted to all types of molecular data, and we highlight crucial issues in microbial ecology that would benefit from this framework and propose ready-to-use R-functions to easily set up our approach.  
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  ISSN 1462-2920 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (up) 430  
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