INTRAPOPULATION FEEDING DIVERSITY IN BLUE TILAPIA: EVIDENCE FROM STABLE-ISOTOPE ANALYSES

Stable carbon and nitrogen isotopes (δ13C and δ15N) in animal tissues are largely determined by isotope composition of assimilated food. Variations in δ13C and δ15N values within a fish population are often small as a result of feeding on the same food source. We report here, however, strikingly broad ranges of δ13C (−25.9 to −9.5‰) and δ15N (5.8 to 14.4‰) in an exotic fish from a Florida lake. Together with isotope data for food sources and gut contents, we demonstrate significant diet variation within a population of blue tilapia.