Experimentally derived incorporation rates and diet-to-tissue discrimination values for carbon and nitrogen stable isotopes in gray wolves (Canis lupus) fed a marine diet

Abstract

Recent studies have noted the differential effects of marine versus terrestrial diets on the carbon and nitrogen stable isotope (13C and 15N, respectively) diet-to-tissue discrimination values and incorporation rates for omnivorous and carnivorous mammals. Inaccurate estimates of these parameters may result in misrepresentation of diet composition or in the timing of diet shifts. Here, we present the results of a diet-switch experiment designed to estimate diet-to-tissue discrimination values and incorporation rates for tissues of gray wolves (Canis lupus Linnaeus, 1758) fed a diet of Pacific salmon (genus Oncorhynchus Suckley, 1861). Our results demonstrate substantial differences in both parameters between wolves maintained on a marine (salmon) diet and wolves maintained on terrestrially sourced prey (beef, Bos taurus Linnaeus, 1758). Increased awareness of the significance of marine resources to omnivorous and carnivorous consumers, like wolves, highlights the importance of phenomenological and mechanistic understandings of the effects of fish and other marine prey on dietary investigations based on stable isotopes.