Tissue-specific turnover rates and trophic enrichment of stable N and C isotopes in juvenile Atlantic cod Gadus morhua fed three different diets

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 461:197-209 (2012) - DOI: https://doi.org/10.3354/meps09871 Tissue-specific turnover rates and trophic enrichment of stable N and C isotopes in juvenile Atlantic cod Gadus morhua fed three different diets Torben Ankjærø, Jens Tang Christensen, Peter Grønkjær* Department of Bioscience, Marine Ecology, Aarhus University, 8000 Aarhus C, Denmark *Email: peter.groenkjaer@biology.au.dk ABSTRACT: A 150 d laboratory diet-shift study was conducted on juvenile Atlantic cod Gadus morhua L. to examine (1) stable nitrogen and carbon isotope turnover rates, (2) the tissue-specific relative contribution of metabolism and growth to isotopic change, and (3) diet−tissue enrichment of the isotopes in white muscle, heart, whole blood, and cranial bone collagen. Time- and growth-based models described the change in δ15N and δ13C of the tissues following a diet shift from pelleted food to either blue mussels Mytilus edulis L., sandeel Ammodytes marinus Raitt., or whiting Merlangius merlangus L. diets. Cod growth rates ranged from 1.5 to 2.0% d−1, with the exception of whiting-fed cod that experienced a cessation in growth after Day 86. Isotope turnover rates, expressed as half-lives (T½), differed little between tissues as expected in fast-growing fish. For δ15N, heart tissue had the shortest T½ while muscle had the longest (30.7 to 34.8 versus 35.7 to 77.9 d−1; range among diets). Heart tissue also had the shortest δ13C T½, whereas blood had the longest (25.5 to 38.5 versus 49.5 to 60.3 d−1; range among diets). Diet-tissue enrichment varied between 0.8 and 5.1‰ (Δδ15N) and between 0.7 and 2.2‰ (Δδ13C). Growth accounted for most of the isotopic change, except in heart tissue of all cod and in all tissues of whiting-fed cod, where there was a significant effect of metabolism on isotopic change. Despite variability in enrichment among diets and tissues, fish feeding on the 3 diets could be distinguished based on their tissue-specific isotopic signatures. KEY WORDS: Isotopic turnover · Diet shift · 15N · 13C · Nitrogen · Carbon · Growth · Metabolism Full text in pdf format PreviousNextCite this article as: Ankjærø T, Christensen JT, Grønkjær P (2012) Tissue-specific turnover rates and trophic enrichment of stable N and C isotopes in juvenile Atlantic cod Gadus morhua fed three different diets. Mar Ecol Prog Ser 461:197-209. https://doi.org/10.3354/meps09871 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 461. Online publication date: August 08, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.