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Auteur (up) Annasawmy, P.; Cherel, Y.; Romanov, E.; Le Loc'h, F.; Menard, F.; Ternon, J.-F.; Marsac, F. doi  openurl
  Titre Stable isotope patterns of mesopelagic communities over two shallow seamounts of the south-western Indian Ocean Type Article scientifique
  Année 2020 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.  
  Volume 176 Numéro Pages 104804  
  Mots-Clés biogeochemical provinces; Crustaceans; delta C-13; delta N-15; discrimination factors; feeding ecology; Fish; food-web structure; Micronekton; mozambique channel; particulate organic-matter; Squid; Trophic level; trophic structure; vertical-distribution; water column; yellowfin tuna  
  Résumé The stable carbon (delta C-13) and nitrogen (delta N-15) isotope values of soft tissues of micronekton (crustaceans, squid, mesopelagic fish) and zooplankton were measured from organisms collected on the RV Antea at two seamounts located in the south-western Indian Ocean: La Perouse (summit depth similar to 60 m) and “MAD-Ridge” (thus named in this study; summit depth similar to 240 m). Surface particulate organic matter (POM-Surf) showed higher delta C-13 at the more productive MAD-Ridge than at the oligotrophic La Perouse seamount. Particulate organic matter and zooplankton were depleted in N-15 at La Pemuse pinnacle compared with MAD-Ridge. Gelatinous organisms and crustaceans occupied the lowest and intermediate tmphic levels (TL similar to 2 and 3 respectively) at both seamounts. Mesopelagic fish and smaller-sized squid sampled at both seamounts occupied TL similar to 3 to 4, whereas the large nektonic squid, Ommastrephes bartramii, collected at MAD-Ridge only, exhibited a TL of similar to 5. The delta N-15 values of common open-water mesopelagic taxa were strongly influenced by specimen size and feeding habits at both seamounts, with an increase in delta N-15 values with increasing size. Carnivorous fish species sampled exclusively over the seamounts' flanks and summits exhibited TL values of similar to 4, irrespective of their wide size ranges. The work could not demonstrate any differences in delta C-13 values of mesopelagic fish between the seamounts and the surrounding oceanic areas. The study segregated clusters of mesopelagic organisms according to their delta C-13 and delta N-15 values, with variations in stable isotope values reflecting a complex range of processes possibly linked to productivity as well as biological and ecological traits of the species (size and feeding mode).  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0967-0645 ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000556810400002 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2835  
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