On the Use of Stable Isotopes in Trophic Ecology

TLDR

Stable isotope analysis is increasingly used to reconstruct diets, map trophic relationships, and build food webs, with subdisciplines such as mixing models, incorporation dynamics, lipid correction, routing, and compound‑specific analysis emerging. The authors expect advances in SIA through method and model standardization, experimental calibration of parameters, and further development of routing and compound‑specific techniques. SIA faces limitations including variable isotopic signatures, limited taxonomic and ecosystem coverage, dependence on literature values, absence of canonical models, unrealistic assumptions, low predictive power, and few experimental validations.

Abstract

Stable isotope analysis (SIA) has proven to be a useful tool in reconstructing diets, characterizing trophic relationships, elucidating patterns of resource allocation, and constructing food webs. Consequently, the number of studies using SIA in trophic ecology has increased exponentially over the past decade. Several subdisciplines have developed, including isotope mixing models, incorporation dynamics models, lipid-extraction and correction methods, isotopic routing models, and compound-specific isotopic analysis. As with all tools, there are limitations to SIA. Chief among these are multiple sources of variation in isotopic signatures, unequal taxonomic and ecosystem coverage, over-reliance on literature values for key parameters, lack of canonical models, untested or unrealistic assumptions, low predictive power, and a paucity of experimental studies. We anticipate progress in SIA resulting from standardization of methods and models, calibration of model parameters through experimentation, and continued development of several recent approaches such as isotopic routing models and compound-specific isotopic analysis.