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Auteur (up) Duffy, L.M.; Kuhnert, P.; Pethybridge, H.R.; Young, J.W.; Olson, R.J.; Logan, J.M.; Goñi, N.; Romanov, E.; Allain, V.; Staudinger, M.; Abecassis, M.; Choy, C.A.; Hobday, A.J.; Simier, M.; Galván-Magaña, F.; Potier, M.; Ménard, F. url  doi
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  Titre Global trophic ecology of yellowfin, bigeye, and albacore tunas: understanding predation on micronekton communities at ocean-basin scales Type Article scientifique
  Année 2017 Publication Revue Abrégée Deep Sea Research Part II: Topical Studies in Oceanography  
  Volume 140 Numéro Pages 55-73  
  Mots-Clés classification trees; climate changes; ecosystems; food webs; inter-ocean comparison; macroecology; Meta-analysis; trophic relationships  
  Résumé Predator-prey interactions for three commercially valuable tuna species: yellowfin (Thunnus albacares), bigeye (T. obesus), and albacore (T. alalunga), collected over a 40-year period from the Pacific, Indian, and Atlantic Oceans, were used to quantitatively assess broad, macro-scale trophic patterns in pelagic ecosystems. Analysis of over 14,000 tuna stomachs, using a modified classification tree approach, revealed for the first time the global expanse of pelagic predatory fish diet and global patterns of micronekton diversity. Ommastrephid squids were consistently one of the top prey groups by weight across all tuna species and in most ocean bodies. Interspecific differences in prey were apparent, with epipelagic scombrid and mesopelagic paralepidid fishes globally important for yellowfin and bigeye tunas, respectively, while vertically-migrating euphausiid crustaceans were important for albacore tuna in the Atlantic and Pacific Oceans. Diet diversity showed global and regional patterns among tuna species. In the central and western Pacific Ocean, characterized by low productivity, a high diversity of micronekton prey was consumed while low prey diversity was evident in highly productive coastal waters where upwelling occurs. Spatial patterns of diet diversity were most variable in yellowfin and bigeye tunas while a latitudinal diversity gradient was observed with lower diversity in temperate regions for albacore tuna. Sea-surface temperature was a reasonable predictor of the diets of yellowfin and bigeye tunas, whereas chlorophyll-a was the best environmental predictor of albacore diet. These results suggest that the ongoing expansion of warmer, less productive waters in the world’s oceans may alter foraging opportunities for tunas due to regional changes in prey abundances and compositions.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0967-0645 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2102  
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Auteur (up) Escalas, A.; Ferraton, F.; Paillon, C.; Vidy, G.; Carcaillet, F.; Salen-Picard, C.; Le Loc'h, F.; Richard, P.; Darnaude, A.M. doi  openurl
  Titre Spatial variations in dietary organic matter sources modulate the size and condition of fish juveniles in temperate lagoon nursery sites Type Article scientifique
  Année 2015 Publication Revue Abrégée Estuar. Coast. Shelf Sci.  
  Volume 152 Numéro Pages 78-90  
  Mots-Clés coastal lagoon; continental inputs; diet; fish; food webs; fresh-water flow; gilthead sea bream; isotope ratios; lagoon; marine nurseries; nursery; sole solea-solea; sparus-aurata; Stable isotopes; stable-isotopes; trophic ecology  
  Résumé Effective conservation of marine fish stocks involves understanding the impact, on population dynamics, of intra-specific variation in nursery habitats use at the juvenile stage. In some regions, an important part of the catching effort is concentrated on a small number of marine species that colonize coastal lagoons during their first year of life. To determine the intra-specific variation in lagoon use by these fish and their potential demographic consequences, we studied diet spatiotemporal variations in the group 0 juveniles of a highly exploited sparid, the gilthead seabream (Sparus aurata L), during their similar to 6 months stay in a NW Mediterranean lagoon (N = 331, SL = 25-198 mm) and traced the origin of the organic matter in their food webs, at two lagoon sites with contrasted continental inputs. This showed that the origin (marine, lagoonal or continental) of the organic matter (OM) available in the water column and the sediment can vary substantially within the same lagoon, in line with local variations in the intensity of marine and continental inputs. The high trophic plasticity of S. aurata allows its juveniles to adapt to resulting differences in prey abundances at each site during their lagoon residency, thereby sustaining high growth irrespective of the area inhabited within the lagoon. However, continental POM incorporation by the juveniles through their diet (of 21-37% on average depending on the site) is proportional to its availability in the environment and could be responsible for the greater fish sizes (of 28 mm SL on average) and body weights (of 40.8 g on average) observed at the site under continental influence in the autumn, when the juveniles are ready to leave the lagoon. This suggests that continental inputs in particulate OM, when present, could significantly enhance fish growth within coastal lagoons, with important consequences on the local population dynamics of the fish species that use them as nurseries. As our results indicate that continental OM can represent up to 62% of the flesh of the juveniles originating from these ecosystems, particular care should be taken to preserve or improve the chemical quality of riverine inputs to coastal lagoons. (C) 2014 Elsevier Ltd. All rights reserved.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0272-7714 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1192  
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Auteur (up) Jacquet, C.; Moritz, C.; Morissette, L.; Legagneux, P.; Massol, F.; Archambault, P.; Gravel, D. doi  openurl
  Titre No complexity-stability relationship in empirical ecosystems Type Article scientifique
  Année 2016 Publication Revue Abrégée Nat. Commun.  
  Volume 7 Numéro Pages 12573  
  Mots-Clés biodiversity; body-size; connectance; diversity; ecopath; interaction strengths; models; perturbations; real food webs; systems  
  Résumé Understanding the mechanisms responsible for stability and persistence of ecosystems is one of the greatest challenges in ecology. Robert May showed that, contrary to intuition, complex randomly built ecosystems are less likely to be stable than simpler ones. Few attempts have been tried to test May's prediction empirically, and we still ignore what is the actual complexity-stability relationship in natural ecosystems. Here we perform a stability analysis of 116 quantitative food webs sampled worldwide. We find that classic descriptors of complexity (species richness, connectance and interaction strength) are not associated with stability in empirical food webs. Further analysis reveals that a correlation between the effects of predators on prey and those of prey on predators, combined with a high frequency of weak interactions, stabilize food web dynamics relative to the random expectation. We conclude that empirical food webs have several non-random properties contributing to the absence of a complexity-stability relationship.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 2041-1723 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1638  
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Auteur (up) Jacquet, C.; Mouillot, D.; Kulbicki, M.; Gravel, D. doi  openurl
  Titre Extensions of Island Biogeography Theory predict the scaling of functional trait composition with habitat area and isolation Type Article scientifique
  Année 2017 Publication Revue Abrégée Ecol. Lett.  
  Volume 20 Numéro 2 Pages 135-146  
  Mots-Clés Allometric theory; animal abundance; body-size; body-size distributions; complex food webs; coral-reef fishes; diversity; Ecology; evolution; Food web; global patterns; island biogeography; population-density; species richness; tropical reefs  
  Résumé The Theory of Island Biogeography (TIB) predicts how area and isolation influence species richness equilibrium on insular habitats. However, the TIB remains silent about functional trait composition and provides no information on the scaling of functional diversity with area, an observation that is now documented in many systems. To fill this gap, we develop a probabilistic approach to predict the distribution of a trait as a function of habitat area and isolation, extending the TIB beyond the traditional species-area relationship. We compare model predictions to the body-size distribution of piscivorous and herbivorous fishes found on tropical reefs worldwide. We find that small and isolated reefs have a higher proportion of large-sized species than large and connected reefs. We also find that knowledge of species body-size and trophic position improves the predictions of fish occupancy on tropical reefs, supporting both the allometric and trophic theory of island biogeography. The integration of functional ecology to island biogeography is broadly applicable to any functional traits and provides a general probabilistic approach to study the scaling of trait distribution with habitat area and isolation.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 1461-023x ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2087  
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Auteur (up) Lotze, H.K.; Tittensor, D.P.; Bryndum-Buchholz, A.; Eddy, T.D.; Cheung, W.W.L.; Galbraith, E.D.; Barange, M.; Barrier, N.; Bianchi, D.; Blanchard, J.L.; Bopp, L.; Büchner, M.; Bulman, C.M.; Carozza, D.A.; Christensen, V.; Coll, M.; Dunne, J.P.; Fulton, E.A.; Jennings, S.; Jones, M.C.; Mackinson, S.; Maury, O.; Niiranen, S.; Oliveros-Ramos, R.; Roy, T.; Fernandes, J.A.; Schewe, J.; Shin, Y.-J.; Silva, T.A.M.; Steenbeek, J.; Stock, C.A.; Verley, P.; Volkholz, J.; Walker, N.D.; Worm, B. url  doi
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  Titre Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change Type Article scientifique
  Année 2019 Publication Revue Abrégée Pnas  
  Volume 116 Numéro 26 Pages 12907-12912  
  Mots-Clés climate change impacts; global ecosystem modeling; marine food webs; model intercomparison; uncertainty  
  Résumé While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (±4% SD) under low emissions and 17% (±11% SD) under high emissions by 2100, with an average 5% decline for every 1 °C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.  
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  ISSN 0027-8424, 1091-6490 ISBN Médium  
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  Notes WOS:000472719100059 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2586  
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