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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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  Numéro d'Appel (up) collection 313  
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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 (up) LL @ pixluser @ collection 369  
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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 (up) LL @ pixluser @ collection 245  
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Auteur Navarro, J.; Cardador, L.; Fernández, Á.M.; Bellido, J.M.; Coll, M. url  doi
openurl 
  Titre Differences in the relative roles of environment, prey availability and human activity in the spatial distribution of two marine mesopredators living in highly exploited ecosystems Type Article scientifique
  Année 2016 Publication Revue Abrégée J. Biogeogr.  
  Volume 43 Numéro 3 Pages 440-450  
  Mots-Clés deviance partitioning; elasmobranchs; environmental variables; human stressors; indicator species; marine biodiversity; Marine conservation; Mediterranean Sea; Raja asterias; Scyliorhinus canicula  
  Résumé Aim Identifying the main factors affecting the spatial distribution of marine predators is essential in order to evaluate their distribution patterns, predict the potential impact of human activities on their populations and design accurate management actions. This information is also valuable from a more general management perspective, as marine predators are often considered indicators of habitat quality. In this context, we aimed to determine the degree to which environmental features, prey availability and human activities interact and influence spatial distribution of two marine mesopredator elasmobranchs, the small-spotted catshark (Scyliorhinus canicula) and the Mediterranean starry ray (Raja asterias), living in a highly human-exploited environment. Location Mediterranean Sea. Methods With information obtained from an extended experimental survey, we investigated the relative importance of environmental variables, prey availability and human activities on the spatial distribution of the abundance, biomass and occurrence rate of these marine mesopredators using deviance partitioning analyses. Results Our results revealed that environmental variables were the most important factors explaining the spatial distribution of Mediterranean starry ray, whereas small-spotted catshark distribution was also influenced by prey availability and human factors. From a management point of view, these findings suggest that Mediterranean starry ray could be a good candidate as an indicator species of demersal environmental quality. On the other hand, the distribution of the small-spotted catshark, which responds in an interactive and complex way to environment, prey availability and particular human activities, may be misleading as an environmental indicator. Main conclusions The spatial distribution of elasmobranchs in highly human-impacted marine areas can reflect the interactive and combined effects of multiple factors. To avoid misunderstandings, attention should be paid to statistical procedures allowing the separation of pure and joint contribution of the factors driving the observed spatial patterns.  
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  ISSN 1365-2699 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ alain.herve @ collection 1538  
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Auteur Pool, T.K.; Cucherousset, J.; Boulêtreau, S.; Villeger, S.; Strecker, A.L.; Grenouillet, G. url  doi
openurl 
  Titre Increased taxonomic and functional similarity does not increase the trophic similarity of communities Type Article scientifique
  Année 2016 Publication Revue Abrégée Global Ecology and Biogeography  
  Volume 25 Numéro 1 Pages 46-54  
  Mots-Clés Alpha diversity; Beta diversity; compositional similarity; functional diversity; trophic diversity  
  Résumé Aim Despite a long-standing research interest in the association between the biodiversity (i.e. taxonomic and functional composition) and trophic structure of communities, our understanding of the relationship remains limited. Community assembly theory predicts that niche partitioning will result in communities with a diverse array of functional traits, which in turn may facilitate a correspondingly diverse array of trophic interactions that define the trophic niche of those communities. The aim of our study is to test this prediction. Location North America. Methods We built a database composed of functional traits and stable isotope values (δ13C and δ15N) for 63 freshwater fish communities containing 109 species in 34 lentic and 29 lotic ecosystems. First, using linear mixed models (i.e. an alpha-diversity approach), we tested whether the taxonomic diversity of communities was positively associated with their functional diversity and if their functional diversity was positively associated with their trophic diversity. Second, we assessed the taxonomic, functional and trophic similarity of communities using multiple regression on distance matrices (MRM) and their respective ‘turnover’ and ‘nestedness-resultant’ components to test if the taxonomic similarity of communities was positively correlated with their functional similarity and if their functional similarity was positively associated with their trophic similarity (i.e. a beta-diversity approach). Results We found that the functional diversity of communities increased as their taxonomic diversity increased. Similarly, the trophic diversity of communities increased as their functional diversity increased. The pairwise taxonomic and functional similarity of communities were also positively associated, but there was a weak relationship between the functional and trophic similarities of communities. Main conclusions Our study demonstrates that communities with similar functional characteristics can have disparate food web structures, suggesting that additional site-specific factors influence community variation in trophic niche geometry. Determining the relative importance of functional characteristics and site-specific factors in shaping trophic interactions is crucial for a better understanding of how future species loss and species introductions will affect food web structure and ecosystem functioning.  
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  ISSN 1466-8238 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ alain.herve @ collection 1540  
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