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Auteur Coll, M.; Steenbeek, J.; Sole, J.; Palomera, I.; Christensen, V. doi  openurl
  Titre Modelling the cumulative spatial-temporal effects of environmental drivers and fishing in a NW Mediterranean marine ecosystem Type Article scientifique
  Année 2016 Publication Revue Abrégée Ecol. Model.  
  Volume 331 Numéro Pages 100-114  
  Mots-Clés acoustic estimation; anchovy engraulis-encrasicolus; climate-change; Cumulative effects; Ecopath with Ecosim; environment; european hake; exploited ecosystems; fishing; food-web model; food webs; hake merluccius-merluccius; protected areas; south catalan sea; trawling disturbance  
  Résumé To realistically predict spatial-temporal dynamics of species in marine ecosystems it is essential to consider environmental conditions in conjunction with human activities and food web dynamics. In this study, we used Ecospace, the spatial-temporal dynamic module of Ecopath with Ecosim (EwE) food web model, to drive a spatially explicit marine food web model representing the Southern Catalan Sea (NW Mediterranean) with various environmental drivers and with fishing. We then evaluated the individual and joint effects of environmental conditions and fishing in various compartments of the food web. First we used a previously developed EwE model fitted to time series of data from 1978 to 2010 as a baseline configuration. The model included 40 functional groups and four fishing fleets. We first ran the original Ecospace spatial-temporal dynamic model using the original habitat configuration, in addition to fishing, and we predicted species distributions and abundances. Afterwards, we ran the new habitat foraging capacity model using the most important environmental drivers linked with the Ebro River delta dynamics (salinity, temperature, and primary production), in addition to depth, substrate and fishing, and we compared results with those from the original implementation of Ecospace. Three commercial species, European hake (Merluccius merluccius), anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus), were used to analyse results. Species distributions more closely matched the empirical information available from the study area when using the new habitat capacity model. Results suggested that the historical impacts of fishing and environmental conditions on the biomass and distributions of hake, anchovy and sardine were not additive, but mainly cumulative with a synergistic or antagonistic effect. Fishing had the highest impact on spatial modelling results while the spatial distribution of primary producers and depth followed in importance. This study contributes to the development of more reliable predictions of regional change in marine ecosystems of the Mediterranean Sea. (C) 2016 Elsevier B.V. All rights reserved.  
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  ISSN 0304-3800 ISBN Médium  
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Auteur 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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  ISSN 2041-1723 ISBN Médium  
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Auteur Mostajir, B.; Amblard, C.; Buffan-Dubau, E.; De Wit, R.; Lensi, R.; Sime-Ngando, T. url  isbn
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  Titre Microbial Food Webs in Aquatic and Terrestrial Ecosystems Type Chapitre de livre
  Année 2015 Publication Revue Abrégée  
  Volume Numéro Pages 485-509  
  Mots-Clés Biodiversity; Biogeochemical cycles; Ecological interactions; Microbial Ecology; Microbial food webs; Microbial loop  
  Résumé In microbial food webs, different types of interactions occur between microorganisms themselves and with meio- and macroorganisms. After an historical and general introduction, the biological components of the microbial food webs in the pelagic and benthic marine and lake ecosystems, as well as in the terrestrial ecosystems, are presented. The functioning of the microbial food webs in different ecosystems is illustrated and explained, including the trophic pathways and transfer of matter from microbial food webs toward meio- and macroorganisms of the superior trophic levels, the nutrient recycling in the aquatic environments, and the decomposition of organic matter in soils. Finally, the factors regulating microbial food webs, primarily “top-down” and “bottom-up” controls, are described with a special focus on the role of viruses in the aquatic microbial food webs.  
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  Editeur Springer Netherlands Lieu de Publication Éditeur Bertrand, J.-C.; Caumette, P.; Lebaron, P.; Matheron, R.; Normand, P.; Sime-Ngando, T.  
  Langue en Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé Environmental Microbiology: Fundamentals and Applications  
  Volume de collection Numéro de collection Edition  
  ISSN ISBN 978-94-017-9117-5 978-94-017-9118-2 Médium  
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Auteur van Gils, J.A.; van der Geest, M.; Jansen, E.J.; Govers, L.L.; de Fouw, J.; Piersma, T. url  openurl
  Titre Trophic cascade induced by molluscivore predator alters pore-water biogeochemistry via competitive release of prey Type Article scientifique
  Année 2012 Publication Revue Abrégée Ecology  
  Volume 93 Numéro Pages 1143-1152  
  Mots-Clés Banc d'Arguin, Mauritania bivalves (Dosinia isocardia, Loripes lucinalis) facilitation growth rate hydrogen sulfide interspecific competition predation predator-exclosure experiment Red Knot, Calidris canutus canutus seagrass beds top-down effect toxicity knots calidris-canutus food webs ecological consequences habitat communities coexistence depletion bivalvia sulfide diet  
  Résumé Effects of predation may cascade down the food web. By alleviating interspecific competition among prey, predators may promote biodiversity, but the precise mechanisms of how predators alter competition have remained elusive. Here we report on a predator-exclosure experiment carried out in a tropical intertidal ecosystem, providing evidence for a three-level trophic cascade induced by predation by molluscivore Red Knots (Calidris canutus) that affects pore water biogeochemistry. In the exclosures the knots' favorite prey (Dosinia isocardia) became dominant and reduced the individual growth rate in an alternative prey (Loripes lucinalis). Dosinia, a suspension feeder, consumes suspended particulate organic matter (POM), whereas Loripes is a facultative mixotroph, partly living on metabolites produced by sulfur-oxidizing chemoautotrophic bacteria, but also consuming suspended POM. Reduced sulfide concentrations in the exclosures suggest that, without predation on Dosinia, stronger competition for suspended POM forces Loripes to rely on energy produced by endosymbiotic bacteria, thus leading to an enhanced uptake of sulfide from the surrounding pore water. As sulfide is toxic to most organisms, this competition-induced diet shift by Loripes may detoxify the environment, which in turn may facilitate other species. The inference that predators affect the toxicity of their environment via a multi-level trophic cascade is novel, but we believe it may be a general phenomenon in detritus-based ecosystems.  
  Adresse [van Gils, Jan A.; van der Geest, Matthijs; Jansen, Erik J.; de Fouw, Jimmy; Piersma, Theunis] NIOZ Royal Netherlands Inst Sea Res, Dept Marine Ecol, NL-1790 AB Den Burg, Texel, Netherlands. [Govers, Laura L.] Radboud Univ Nijmegen, Fac Sci, Inst Water & Wetland Res, Dept Environm Sci, NL-6500 GL Nijmegen, Netherlands. [Piersma, Theunis] Univ Groningen, CEES, Anim Ecol Grp, NL-9700 CC Groningen, Netherlands. van der Geest, M (reprint author), NIOZ Royal Netherlands Inst Sea Res, Dept Marine Ecol, POB 59, NL-1790 AB Den Burg, Texel, Netherlands matthijs.van.der.geest@nioz.nl  
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  ISSN 0012-9658 ISBN Médium  
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  Notes ISI Document Delivery No.: 946QK Times Cited: 0 Cited Reference Count: 60 van Gils, Jan A. van der Geest, Matthijs Jansen, Erik J. Govers, Laura L. de Fouw, Jimmy Piersma, Theunis Nwo-wotro[w.01.65.221.00] We are grateful to the staff of the Parc National du Banc d'Arguin for allowing us to work and stay in the area under their management. In 2009 we had the pleasant company of Tjisse van der Heide, Han Olff, and Erik Rosendaal, and in 2010 Brecht De Meulenaer joined us. Erik Rosendaal processed fecal samples, and Jeroen Onrust determined shell dry masses. Dick Visser redrew the figures. This work was funded by the NWO-WOTRO Integrated Programme grant W.01.65.221.00 awarded to T. Piersma. Ecological soc amer Washington Approuvé pas de  
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Auteur 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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