RAPID COMMUNICATION Stable N and C isotopes in the organic matrix of fish otoliths: validation of a new approach for studying spatial and temporal changes in the trophic structure of aquatic ecosystems

摘要: Stable isotope studies of long-term ecosystem change are often hampered by lack archived tissue samples. Here, we provide a reliable method for extracting the organic matrix from fish otoliths, demonstrate differences in values between soluble and insoluble fractions, trophic enrichment factors (). The analyses were per- formed on otoliths wild-caught adult Atlantic cod (Gadus morhua) 6-month diet-switch experiment with juvenile cod. Acid hydrolysis otolith powder followed ultrafiltration enabled us to purify separate material. There was significant 1.72‰ 0.15‰ difference 15N 13C, respectively, fraction otolith. This emphasizes need separation two fractions before analysis. diet-specific (otolith-diet) varied −0.20‰ 0.31‰ nitrogen 0.09‰ 0.23‰ carbon. In conclusion, provides an attractive archive material ecological stable analysis that has potential important insights into historic changes structure aquatic ecosystems. Resume : Les etudes des changements ecosystemiques along terme reposant sur les isotopes stables sont souvent limitees par l'absence d'echantillons archives de tissus. Nous presentons une methode fiable pour extraire la matrice organique d'otolites poissons, nous demontrons dans valeurs isotopiques organiques solubles et insolubles determinons facteurs d'enrichissement trophique ont ete realisees otolites morues adultes prises al'etat sauvage issus d'une experience changement regime alimentaire juveniles. La purification du materiel hydrolyse acide poudres d'otolite suivie ultrafiltration. Des significatives 15 Ne t13C, 1,72 ‰ 0,15 respectivement, observees entre otolites. Ces soulignent necessite separer ces deux prealablement al'analyse. L'enrichissement associe au allait −0,20 ` 0,31 l'azote, 0,09 0,23 le carbone. Il est possible conclure que constitue matiere interessante pouvant etre utilisee l'analyse ecologique qui peut fournir l'information importante historiques ala ecosystemes aquatiques. (Traduit Redaction)