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Auteur Sirot, C.; Gronkjaer, P.; Pedersen, J.B.; Panfili, J.; Zetina-Rejon, M.; Tripp-Valdez, A.; Ramos-Miranda, J.; Flores-Hernandez, D.; Sosa-Lopez, A.; Darnaude, A.M. doi  openurl
  Titre Using otolith organic matter to detect diet shifts in Bardiella chrysoura, during a period of environmental changes Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.  
  Volume 575 Numéro Pages 137-152  
  Mots-Clés aquatic ecosystems; Bairdiella chrysoura; climate-change; Coastal ecosystem; fish otoliths; food-web; movement patterns; prey availability; Stable isotope analysis; stable-isotope analysis; survival; temporal-changes; terminos lagoon; Trophic ecology; Trophic interactions  
  Résumé Accurate knowledge on fish trophic ecology and its modifications is crucial for understanding the impact of global change on ecosystems. In this context, we investigated the value of the delta C-13 and delta N-15 of otolith soluble organic matter (SOM) for identifying temporal diet shifts in American silver perch Bairdiella chrysoura over a 30-yr period characterized by strong changes in its population size and habitats within the Terminos Lagoon (Mexico). We first compared the otolith SOM isotopic signatures from present-clay adults to those of muscle and the main local prey. Our results suggest that otolith SOM can be confidently extracted and analyzed for both present and past otoliths of this species. The mean otolith SOM signatures obtained (-15.92 +/- 1.35%, for delta C-13 and 9.38 +/- 0.93%, for delta N-15) were consistent with those of the diet as 85% of the individual signatures were included within the prey isotopic niche area. Moreover, this study supports a trophic enrichment factor between diet and otolith (TEFdiet-otolith) close to 0 for delta N-15, while for delta C-13, the TEFololith-muscle of +0.02% warrants further investigation. Then, we compared past and contemporary otolith SOM signatures to investigate temporal diet shifts in B. chrysoura. This showed that 613C and delta N-15 differed significantly between the past and present period even if the temporal shift remained relatively small (respectively +1.17%, and 0.55%). The present study substantiates the use of otolith SOM delta C-13 and delta N-15 as a proxy of fish present and past trophic position, opening the possibility for major progress in studies of temporal changes in food web ecology.  
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  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2172  
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Auteur Navarro, J.; Saez-Liante, R.; Albo-Puigserver, M.; Coll, M.; Palomera, I. doi  openurl
  Titre Feeding strategies and ecological roles of three predatory pelagic fish in the western Mediterranean Sea Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.  
  Volume 140 Numéro Pages 9-17  
  Mots-Clés diet; ecosystem structure; iberian peninsula; indian-ocean; isotope ratios; Marine predators; Pelagic ecosystem; Stable isotopes; stable-isotopes; Stomach contents; swordfish; top predators; Trophic ecology; trophic level; xiphias-gladius; Yellowfin tuna  
  Résumé Knowing the feeding ecology of marine predators is pivotal to developing an understanding of their ecological role in the ecosystem and determining the trophic relationships between them. Despite the ecological importance of predatory pelagic fish species, research on these species in the Mediterranean Sea is limited. Here, by combining analyses of stomach contents and stable isotope values, we examined the feeding strategies of swordfish, Xiphias gladius, little tunny, Euthynnus alletteratus and Atlantic bonito, Sarda sarda, in the western Mediterranean Sea. We also compared the trophic niche and trophic level of these species with published information of other sympatric pelagic predators present in the ecosystem. Results indicated that, although the diet of the three species was composed mainly by fin-fish species, a clear segregation in their main feeding strategies was found. Swordfish showed a generalist diet including demersal species such as blue whiting, Micromesistius poutassou, and European hake, Merluccius merluccius, and pelagic fin-fish such as barracudina species (Arctozenus risso and Lestidiops jayakari) or small pelagic fish species. Little tunny and Atlantic bonito were segregated isotopically between them and showed a diet basically composed of anchovy, Engraulis encrasicolus, and round sardinella, Sardinella aurita, and sardines, Sardina pilchardus, respectively. This trophic segregation, in addition to potential segregation by depth, is likely a mechanism that allows their potential coexistence within the same pelagic habitat. When the trophic position of these three predatory pelagic fish species is compared with other pelagic predators such as bluefin tuna, Thunnus thynnus, and dolphinfish, Coryphaena hippurus, present in the western Mediterranean Sea, we found that they show similar intermediate trophic position in the ecosystem. In conclusion, the combined stomach and isotopic results highlight, especially for little tunny and Atlantic bonito, the trophic importance of Clupeoid species in their diet. In addition, the importance of demersal resources for swordfish provides evidence for the pelagic-demersal coupling of the ecosystem and the need to manage marine resources in an integrated way. (C) 2016 Elsevier Ltd. All rights reserved.  
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  ISSN 0967-0645 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2175  
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Auteur Leboulanger, C.; Agogué, H.; Bernard, C.; Bouvy, M.; Carré, C.; Cellamare, M.; Duval, C.; Fouilland, E.; Got, P.; Intertaglia, L.; Lavergne, C.; Floc’h, E.L.; Roques, C.; Sarazin, G. url  doi
openurl 
  Titre Microbial Diversity and Cyanobacterial Production in Dziani Dzaha Crater Lake, a Unique Tropical Thalassohaline Environment Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Plos One  
  Volume 12 Numéro 1 Pages e0168879  
  Mots-Clés Biomass (ecology); Cyanobacteria; Lakes; Oxygen; Phytoplankton; Ribosomal RNA; Sea water; Surface water  
  Résumé This study describes, for the first time, the water chemistry and microbial diversity in Dziani Dzaha, a tropical crater lake located on Mayotte Island (Comoros archipelago, Western Indian Ocean). The lake water had a high level of dissolved matter and high alkalinity (10.6–14.5 g L-1 eq. CO32-, i.e. 160–220 mM compare to around 2–2.5 in seawater), with salinity up to 52 psu, 1.5 higher than seawater. Hierarchical clustering discriminated Dziani Dzaha water from other alkaline, saline lakes, highlighting its thalassohaline nature. The phytoplankton biomass was very high, with a total chlorophyll a concentration of 524 to 875 μg chl a L-1 depending on the survey, homogeneously distributed from surface to bottom (4 m). Throughout the whole water column the photosynthetic biomass was dominated (>97% of total biovolume) by the filamentous cyanobacteria Arthrospira sp. with a straight morphotype. In situ daily photosynthetic oxygen production ranged from 17.3 to 22.2 g O2 m-2 d-1, consistent with experimental production / irradiance measurements and modeling. Heterotrophic bacterioplankton was extremely abundant, with cell densities up to 1.5 108 cells mL-1 in the whole water column. Isolation and culture of 59 Eubacteria strains revealed the prevalence of alkaliphilic and halophilic organisms together with taxa unknown to date, based on 16S rRNA gene analysis. A single cloning-sequencing approach using archaeal 16S rDNA gene primers unveiled the presence of diverse extremophilic Euryarchaeota. The water chemistry of Dziani Dzaha Lake supports the hypothesis that it was derived from seawater and strongly modified by geological conditions and microbial activities that increased the alkalinity. Dziani Dzaha has a unique consortium of cyanobacteria, phytoplankton, heterotrophic Eubacteria and Archaea, with very few unicellular protozoa, that will deserve further deep analysis to unravel its uncommon diversity. A single taxon, belonging to the genus Arthrospira, was found responsible for almost all photosynthetic primary production.  
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  ISSN 1932-6203 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1702  
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Auteur Chevrinais, M.; Jacquet, C.; Cloutier, R. doi  openurl
  Titre Early establishment of vertebrate trophic interactions: Food web structure in Middle to Late Devonian fish assemblages with exceptional fossilization Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Bull. Geosci.  
  Volume 92 Numéro 4 Pages 491-510  
  Mots-Clés north-america; bottom-up; body-size; predator; top-down; bottom-up control; coordinated stasis; Devonian; digestive contents; ecomorphology; escuminac formation; foraging ecology; fossil fish; fossil record; pahteoecology; prey size relationships; top-down control  
  Résumé In past and present ecosystems, trophic interactions determine material and energy transfers among species, regulating population dynamics and community stability. Food web studies in past ecosystems are helpful to assess the persistence of ecosystem structure throughout geological times and to explore the existence of general principles of food web assembly. We determined and compared the trophic structure of two Devonian fish assemblages [(1) the Escuminac assemblage (ca. 380 Ma), Miguasha, eastern Canada and (2) the Lode assemblage (ca. 390 Ma), Straupe, Latvia] with a closer look at the Escuminac assemblage. Both localities are representative of Middle to Late Devonian aquatic vertebrate assemblages in terms of taxonomic richness (ca. 20 species), phylogenetic diversity (all major groups of lower vertebrates) and palaeoenvironment (palaeoestuaries). Fossil food web structures were assessed using different kinds of direct (i.e. digestive contents and bite marks in fossils) and indirect (e.g. ecomoiphological measurements, stratigraphic species co-occurrences) indicators. First, the relationships between predator and prey body size established for the Escuminac fishes are comparable to those of recent aquatic ecosystems, highlighting a consistency of aquatic food web structure across geological time. Second, non-metric dimensional scaling on ecomorphological variables and cluster analysis showed a common pattern of functional groups for both fish assemblages; top predators, predators, primary and secondary consumers were identified. We conclude that Devonian communities were organized in multiple trophic levels and that size-based feeding interactions were established early in vertebrate history.  
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  ISSN 1214-1119 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2251  
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Auteur Mellin, C.; Mouillot, D.; Kulbicki, M.; McClanahan, T.R.; Vigliola, L.; Bradshaw, C.J.A.; Brainard, R.E.; Chabanet, P.; Edgar, G.J.; Fordham, D.A.; Friedlander, A.M.; Parravicini, V.; Sequeira, A.M.M.; Stuart-Smith, R.D.; Wantiez, L.; Caley, M.J. url  doi
openurl 
  Titre Humans and seasonal climate variability threaten large-bodied coral reef fish with small ranges Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Nat Commun  
  Volume 7 Numéro Pages 10491  
  Mots-Clés Biological sciences; Ecology; Oceanography  
  Résumé Coral reefs are among the most species-rich and threatened ecosystems on Earth, yet the extent to which human stressors determine species occurrences, compared with biogeography or environmental conditions, remains largely unknown. With ever-increasing human-mediated disturbances on these ecosystems, an important question is not only how many species can inhabit local communities, but also which biological traits determine species that can persist (or not) above particular disturbance thresholds. Here we show that human pressure and seasonal climate variability are disproportionately and negatively associated with the occurrence of large-bodied and geographically small-ranging fishes within local coral reef communities. These species are 67% less likely to occur where human impact and temperature seasonality exceed critical thresholds, such as in the marine biodiversity hotspot: the Coral Triangle. Our results identify the most sensitive species and critical thresholds of human and climatic stressors, providing opportunity for targeted conservation intervention to prevent local extinctions.  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1537  
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