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Auteur Sardenne, F.; Hollanda, S.; Lawrence, S.; Albert-Arrisol, R.; Degroote, M.; Bodin, N. doi  openurl
  Titre Trophic structures in tropical marine ecosystems: a comparative investigation using three different ecological tracers Type Article scientifique
  Année 2017 Publication Revue Abrégée (up) Ecol. Indic.  
  Volume 81 Numéro Pages 315-324  
  Mots-Clés feeding-behavior; Stable isotopes; food webs; Fatty acids; Mercury; western indian-ocean; gulf-of-mexico; amino-acid; stable-isotope; bioaccumulation; fatty-acid compositions; Indian ocean; mercury exposure; pelagic fishes; Tropical food web  
  Résumé We looked at how three ecological tracers may influence the characterization and interpretation of trophic structures in a tropical marine system, with a view to informing tracer(s) selection in future trophic ecology studies. We compared the trophic structures described by stable isotope compositions (carbon and nitrogen), the total mercury concentration (THg) and levels of essential fatty acids (EFA) at both the individual and species level. Analyses were undertaken on muscle tissue samples from fish and crustacean species caught in the waters surrounding the Seychelles. The carbon isotope composition (delta C-13) correlated to the proportion of arachidonic acid (ARA), whereas the nitrogen isotope composition (delta N-15) correlated to the proportion of docosahexaenoic acid (DHA) and THg. At the individual level, trophic position obtained with these three last tracers are similar. In ' contrast, the eicosapentaenoic acid (EPA) was not clearly correlated to any of the tracers. At the species level, the use of EFA (ARA and DHA), as compared to stable isotopes, resulted in slight structural modifications, mainly in the middle trophic levels. For example, the EFA overestimated the trophic positions of Thunnus alalunga and Etelis coruscans but underestimated the trophic positions of other snappers and groupers. While ARA mainly originates from coastal/benthic areas, DHA is conserved throughout the food web and may be used as a proxy indicator of trophic position. However, metabolic disparities can affect ecological tracers and in turn, distort the trophic structures derived from their results. This is especially true for species with close trophic ecologies. Despite these caveats, we think that analysing at the individual level the wealth of ARA, DHA and THg data that has already been obtained through earlier nutrition or food security studies would enhance our understanding of trophic structures.  
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  ISSN 1470-160x ISBN Médium  
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Auteur 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 (up) 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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  ISSN 1461-023x ISBN Médium  
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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 (up) 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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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 (up) 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 (up) 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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