Current address: Maurice Lamontagne Institute, Department of Fisheries and Oceans, P. O. Box 1000, Mont-Joli, Quebec G5H 3Z4, Canada.
DIET-TISSUE FRACTIONATION OF STABLE CARBON AND NITROGEN ISOTOPES IN PHOCID SEALS
Article first published online: 26 AUG 2006
Marine Mammal Science
Volume 18, Issue 1, pages 182–193, January 2002
How to Cite
Lesage, V., Hammill, M. O. and Kovacs, K. M. (2002), DIET-TISSUE FRACTIONATION OF STABLE CARBON AND NITROGEN ISOTOPES IN PHOCID SEALS. Marine Mammal Science, 18: 182–193. doi: 10.1111/j.1748-7692.2002.tb01027.x
Current address: Norwegian Polar Institute, N-9296 Tromsø, Norway.
- Issue published online: 26 AUG 2006
- Article first published online: 26 AUG 2006
- Received: 29 May 2000 Accepted: 10 May 2001
Diet-tissue isotopic fractionation of carbon (C) and nitrogen (N) isotopes in short- and longer-term diet integrators of diet (i. e., blood serum and red cells), that involve non-invasive sampling techniques was examined using three species of phocid seals (harbor seals, gray seals, and harp seals) fed a known diet. Variability in diet-tissue fractionation values within and between species was also scrutinized to determine the legitimacy of using values obtained from one species to explore trophic positions and diets of other related species. All captive seals raised on a constant diet had tissues enriched in 13C and 15N relative to their diet. Diet-tissue isotopic fractionation values were generally consistent among conspecifics and among phocid species for a given tissue. Trophic isotopic enrichment in 13C was significantly higher in red blood cells (+1.5%±) than in blood serum (+0.8%±), whereas the reverse was observed for nitrogen isotopes (+1.7%± in red cells vs. +3.1%± in serum). However, 13C-depleted lipids were not extracted from blood tissues in this study. This results in a downward bias in the diet-tissue fractionation factors for carbon for both red cells and blood serum, particularly the latter because of their significantly higher lipid contents (x̄± SD = 14.6 ± 2.3%; n= 20; red blood cells 3.8 ± 0.9%±; n= 50, muscle 7.7 ± 2.0; n= 21) in marine mammals.