Stable isotopes in trophic ecology

Stable isotope ratios of plant and animal tissue are a useful tool for reconstructing dietary habits, describing trophic relationships, and constructing food webs. As a result, the number of studies using carbon (d¹³C), nitrogen (d¹⁵N), and hydrogen (d²H) in trophic ecology has increased strongly over the past decade. To understand consumer dietary needs and resource use, researchers have employed a variety of methods, including bulk stable isotope analysis (SIA) as well as compound specific stable isotope analysis (CSIA) of fatty acids and amino acids. This presentation will give an overview of these methods and provide recommendations for method selection. The different approaches are illustrated using studies at the natural abundance level as well as enriched physiological tracers, with a focus on soil food webs. In addition, the innovative methods of fatty acid isotopomer and isotopologue profiling are presented, which are not yet widely used in ecological studies, but have the potential to overcome some of the limitations of current techniques. Combining the different isotope-based applications with further empirical studies of individual dietary habits, promises to greatly advance food web ecology.