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Auteur Sardenne, F.; Hollanda, S.; Lawrence, S.; Albert-Arrisol, R.; Degroote, M.; Bodin, N.
Titre (down) Trophic structures in tropical marine ecosystems: a comparative investigation using three different ecological tracers Type Article scientifique
Année 2017 Publication Revue Abrégée 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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Auteur van Gils, J.A.; van der Geest, M.; Jansen, E.J.; Govers, L.L.; de Fouw, J.; Piersma, T.
Titre (down) 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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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.
Titre (down) 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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Auteur Cresson, P.; Chouvelon, T.; Bustamante, P.; Bănaru, D.; Baudrier, J.; Le Loc'h, F.; Mauffret, A.; Mialet, B.; Spitz, J.; Wessel, N.; Briand, M.J.; Denamiel, M.; Doray, M.; Guillou, G.; Jadaud, A.; Lazard, C.; Noûs, C.; Prieur, S.; Rouquette, M.; Saraux, C.; Serre, S.; Timmerman, C.-A.; Verin, Y.; Harmelin-Vivien, M.
Titre (down) Primary production and depth drive different trophic structure and functioning of fish assemblages in French marine ecosystems Type Article scientifique
Année 2020 Publication Revue Abrégée Progress in Oceanography
Volume Numéro Pages 102343
Mots-Clés benthic-pelagic coupling; fish community; food webs; trophodynamics
Résumé Investigating the drivers of fish assemblage trophic structure is a critical question, in order to better understand ecosystem functioning, predict the effects of perturbations and implement integrated management of exploited marine ecosystems. Ecosystemic surveys enabled the determination of the trophic structure of the fish assemblages in three French marine ecosystems, namely the Eastern English Channel, the Bay of Biscay and the Gulf of Lions, through the simultaneous collection of qualitative (stable isotopes and energy content) and quantitative (biomass) data. In the Bay of Biscay and in the Gulf of Lions, pelagic primary production supported at least 80% of the fish biomass production, and explained the dominance of pelagic species, but with differences resulting from the different productivity. The lower productivity in the oligotrophic Gulf of Lions led to a lower total biomass, energy density as well as the predominance of zooplankton feeders. In contrast, fluxes in the Bay of Biscay were sufficient to support a higher biomass of pelagic piscivores, and of species with higher energy content. In the shallow Eastern English Channel, the respective contributions of pelagic and benthic sources were similar. Bentho-demersal species of higher trophic level dominated this assemblage, because of their ability to exploit both pathways. Results of the present study confirmed that fisheries-focused surveys can be used as efficient platforms to address questions about ecosystem functioning. Here it confirmed the expected differences between ecosystems and the importance of primary production and environment as drivers of fish assemblage structure and functioning. Future studies should nevertheless develop new methods to better assess the paramount role of low trophic level consumers.
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Auteur Cazelles, K.; Mouquet, N.; Mouillot, D.; Gravel, D.
Titre (down) On the integration of biotic interaction and environmental constraints at the biogeographical scale Type Article scientifique
Année 2016 Publication Revue Abrégée Ecography
Volume 39 Numéro 10 Pages 921-931
Mots-Clés biodiversity; climate-change; cooccurrence; distributions; ecological communities; evolutionary; food webs; networks; niche; species distribution models
Résumé Biogeography is primarily concerned with the spatial distribution of biodiversity, including performing scenarios in a changing environment. The efforts deployed to develop species distribution models have resulted in predictive tools, but have mostly remained correlative and have largely ignored biotic interactions. Here we build upon the theory of island biogeography as a first approximation to the assembly dynamics of local communities embedded within a metacommunity context. We include all types of interactions and introduce environmental constraints on colonization and extinction dynamics. We develop a probabilistic framework based on Markov chains and derive probabilities for the realization of species assemblages, rather than single species occurrences. We consider the expected distribution of species richness under different types of ecological interactions. We also illustrate the potential of our framework by studying the interplay between different ecological requirements, interactions and the distribution of biodiversity along an environmental gradient. Our framework supports the idea that the future research in biogeography requires a coherent integration of several ecological concepts into a single theory in order to perform conceptual and methodological innovations, such as the switch from single-species distribution to community distribution.
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ISSN 0906-7590 ISBN Médium
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