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Auteur Pethybridge, H.; BODIN, N.; Arsenault-Pernet, E.-J.; BOURDEIX, J.-H.; BRISSET, B.; BIGOT, J.-L.; ROOS, D.; Peter, M. url  openurl
  Titre Temporal and inter-specific variations in forage fish feeding conditions in the NW Mediterranean: lipid content and fatty acid compositional changes Type Article scientifique
  Année 2014 Publication Revue Abrégée Marine Ecology Progress Series  
  Volume 512 Numéro Pages 39-54  
  Mots-Clés Clupeiformes; ecosystem health; Environmental variations; Nutritional condition; Prey Quality; Trophic markers  
  Résumé We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter-and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource partitioning and niche separation, as inferred from fatty acid profiles, were apparent between species. Sardine showed a more diverse, temporally separated feeding strategy than anchovy, and dietary overlap was higher in winter than summer with sardine having higher markers of copepods, 22:1n11 and 20:1n9. Sprat collected in winter occupied a separate niche area to both sardine and anchovy with higher total lipid content and carnivory biomarker 18:1n9. Our results show that the lipid dynamics of forage fishes can be used to gain quantitative insights into sub-system level changes in species interactions, including prey and predator productivity.  
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  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 1129  
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Auteur LE MAHO, Y.; WHITTINGTON, J.D.; HANUISE, N.; PEREIRA, L.; BOUREAU, M.; BRUCKER, M.; CHATELAIN, N.; COURTECUISSE, J.; CRENNER, F.; FRIESS, B.; GROSBELLET, E.; KERNALEGUEN, L.; OLIVER, F.; SARAUX, C.; VETTER, N.; VIBLANC, V.A.; THIERRY, B.; TREMBLAY, P.; GROSCOLAS, R.; LE BOHEC, C. url  openurl
  Titre Rovers minimize human disturbance in research on wild animals Type Article scientifique
  Année 2014 Publication Revue Abrégée Nature Methods  
  Volume 11 Numéro 12 Pages 1242-1244  
  Mots-Clés  
  Résumé Investigating wild animals while minimizing human disturbance remains an important methodological challenge. When approached by a remote-operated vehicle (rover) which can be equipped to make radio-frequency identifications, wild penguins had significantly lower and shorter stress responses (determined by heart rate and behavior) than when approached by humans. Upon immobilization, the rover-unlike humans-did not disorganize colony structure, and stress rapidly ceased. Thus, rovers can reduce human disturbance of wild animals and the resulting scientific bias.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1548-7091 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 1128  
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Auteur HANEL, R.; STEPPUTTIS, D.; BONHOMMEAU, S.; CASTONGUAY, M.; SCHABER, M.; WYSUJACK, K.; VOBACH, M.; MILLER, M.J. url  openurl
  Titre Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels Type Article scientifique
  Année 2014 Publication Revue Abrégée Naturwissenschaften  
  Volume 101 Numéro 12 Pages 1041-1054  
  Mots-Clés Anguillidae; Anguilliformes; Eel larvae; Population declines; spawning area  
  Résumé The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area.  
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  ISSN 0028-1042 ISBN Médium  
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Auteur BORDIER, C.; SARAUX, C.; VIBLANC, V.A.; GACHOT-NEVEU, H.; BEAUGEY, M.; LE MAHO, Y.; LE BOHEC, C. url  openurl
  Titre Inter-Annual Variability of Fledgling Sex Ratio in King Penguins Type Article scientifique
  Année 2014 Publication Revue Abrégée Plos One  
  Volume 9 Numéro 12 Pages 1-17  
  Mots-Clés  
  Résumé As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (20002009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1:1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.  
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  ISSN 1932-6203 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 1126  
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Auteur Miller, M.J.; Bonhommeau, S.; Munk, P.; Castonguay, M.; Hanel, R.; McCleave, J.D. url  openurl
  Titre A century of research on the larval distributions of the Atlantic eels: a re-examination of the data Type Article scientifique
  Année 2014 Publication Revue Abrégée Biological Reviews  
  Volume Numéro Pages  
  Mots-Clés anguilla; freshwater eels; larval distribution; oceanic fronts.; Sargasso Sea; spawning area  
  Résumé The spawning areas of the Atlantic freshwater eels were discovered about a century ago by the Danish scientistJohannes Schmidt who after years of searching found newly hatched larvae of the European eel, Anguillaanguilla, and the American eel, Anguilla rostrata, in the southern Sargasso Sea. The discovery showed thatanguillid eels migrate thousands of kilometers to offshore spawning areas for reproduction, and that theirlarvae, called leptocephali, are transported equally long distances by ocean currents to their continentalrecruitment areas. The spawning sites were found to be related to oceanographic conditions several decadeslater by German and American surveys from 1979 to 1989 and by a Danish survey in 2007 and a Germansurvey in 2011. All these later surveys showed that spawning occurred within a restricted latitudinal range,between temperature fronts within the Subtropical Convergence Zone of the Sargasso Sea. New data andre-examinations of Schmidt’s data confirmed his original conclusions about the two species having someoverlap in spawning areas. Although there have been additional collections of leptocephali in various parts ofthe North Atlantic, and both otolith research and transport modelling studies have subsequently been carriedout, there is still a range of unresolved questions about the routes of larval transport and durations of migration.This paper reviews the history and basic findings of surveys for anguillid leptocephali in the North Atlantic andanalyses a new comprehensive database that includes 22612 A. anguilla and 9634 A. rostrata leptocephali, whichprovides a detailed view of the spatial and temporal distributions and size of the larvae across the Atlantic basinand in the Mediterranean Sea. The differences in distributions, maximum sizes, and growth rates of the twospecies of larvae are likely linked to the contrasting migration distances to their recruitment areas on eachside of the basin. Anguilla rostrata leptocephali originate from a more western spawning area, grow faster, andmetamorphose at smaller sizes of <70mm than the larvae of A. anguilla, which mostly are spawned further eastand can reach sizes of almost 90 mm. The larvae of A. rostrata spread west and northwest from the spawningarea as they grow larger, with some being present in the western Caribbean and eastern Gulf of Mexico. Larvaeof A. anguilla appear to be able to reach Europe by entering the Gulf Stream system or by being entrainedinto frontal countercurrents that transport them directly northeastward. The larval duration of A. anguillais suggested to be quite variable, but gaps in sampling effort prevent firm conclusions. Although knowledgeabout larval behaviour is lacking, some influences of directional swimming are implicated by the temporaldistributions of the largest larvae. Ocean–atmosphere changes have been hypothesized to affect the survivalof the larvae and cause reduced recruitment, so even after about a century following the discovery of theirspawning areas, mysteries still remain about the marine life histories of the Atlantic eels.  
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