title: Turnover rates of nitrogen stable isotopes in the salt marsh mummichog, Fundulus heteroclitus, following a laboratory diet switch.
abstract: Nitrogen stable isotopes are frequently used in ecological studies to estimate trophic position and determine movement patterns. Knowledge of tissue-specific turnover and nitrogen discrimination for the study organisms is important for accurate interpretation of isotopic data. We measured delta15 N turnover in liver and muscle tissue in juvenile mummichogs, Fundulus heteroclitus, following a laboratory diet switch. Liver tissue turned over significantly faster than muscle tissue suggesting the potential for a multiple tissue stable isotope approach to study movement and trophic position over different time scales; metabolism contributed significantly to isotopic turnover for both liver and muscle. Nitrogen diet-tissue discrimination was estimated at between 0.0 and 1.2 per thousand for liver and -1.0 and 0.2 per thousand for muscle. This is the first experiment to demonstrate a significant variation in delta15 N turnover between liver and muscle tissues in a fish species.
authors.affiliation: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA. jmlogan@cisunix.unh.edu
authors.forename: John
authors.initials: J
authors.lastname: Logan
authors.forename: Heather
authors.initials: H
authors.lastname: Haas
authors.forename: Linda
authors.initials: L
authors.lastname: Deegan
authors.forename: Emily
authors.initials: E
authors.lastname: Gaines
mesh_terms: D000818:Animals; D004032:Diet; D023781:Fundulidae / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes