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Auteur (up) Chassot, E.; Rouyer, T.; Trenkel, V.M.; Gascuel, D. url  doi
  Titre Investigating trophic-level variability in Celtic Sea fish predators Type Article scientifique
  Année 2008 Publication Revue Abrégée Journal of Fish Biology  
  Volume 73 Numéro 4 Pages 763-781  
  Mots-Clés food web; Gam; Indicator; omnivory; Predation; Trophic level  
  Résumé The trophic level (TL) mean and variance, and the degree of omnivory for five Celtic Sea fish predators were estimated using a database of stomach content records characterized by a high level of taxonomic resolution. The predators occupied a high position in the food web, i.e. 4·75 for Atlantic cod Gadus morhua, 4·44 for haddock Melanogrammus aeglefinus, 4·88 for European hake Merluccius merluccius, 5·00 for megrim Lepidorhombus whiffiagonis and 5·27 for whiting Merlangius merlangus. The level of taxonomic resolution of the prey did not greatly affect mean TL predator values; an effect on variance was evident, low resolution masking intra-population variability in TL. Generalized additive models (GAM) were used to explain the variability of predator TL caused by environmental variables (International Council for the Exploration of the Sea, ICES, division and season) and predator characteristics (total length, LT). Significant year, location season and interaction effects were found for some species and with LT at the scale of ICES subdivision. The species-specific variability of TL could be due to spatio-temporal variations in prey availability and in predator selectivity following ontogenetic changes. Omnivorous fish TL was less affected by spatio-temporal variations. In addition, results showed that the omnivory index and TL variability provide dissimilar information on predator feeding strategy. Combining information on TL variability and omnivory allowed between within-individual and between-individual components contributing to trophic niche width to be separated and the type of generalization of fish predators to be identified.  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue en Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1095-8649 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1674  
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