Simple mixing models based on mass balance equations have been used for dietary analyses for several decades. Several factors may complicate these analyses, including overlap in the isotopic composition of food sources, different element concentrations among sources and limitations on the number of sources that can be uniquely distinguished. Complexities of digestive physiology, such as digestibility differences among foods, consumer nutritional status, and differences in elemental routing to various tissues are additional factors to be considered. In this presentation, we first outline the basic isotopic mixing models and their assumptions. We then examine several extensions of mixing model analysis to deal with some of these complicating factors. These extensions include examination of experimental design and the uncertainty in dietary estimates, incorporation of elemental concentration differences among food sources, and increasing the number of food sources that can be examined. Though complex in derivation, spreadsheets and programs have been developed for ease of application and are available at http://www.epa.gov/wed/pages/models.htm
Keywords: stable isotopes, mixing model
Back to Section C Symposium: Stable Isotopes in Basic and Applied Entomology
Back to Section Symposia
Back to The 2003 ESA Annual Meeting and Exhibition