Stable isotopes and food chain length
Stable isotopes have proved powerful biomarkers for addressing a number of questions in ecology and evolution that appeared otherwise intractable. For example, stable isotope methods allowed rapid progress in addressing long-standing questions about the determinants of food chain length, a measure of the height of a food web. Here I explore how stable isotope analyses allowed ecologists to test a number of important hypotheses about what determines food chain length and how those test fundamentally changed our understanding of how and why food chain length varies across ecosystems. I will also address how new methods may address a number of remaining unanswered questions about food chain length.
Stable isotope analyses have helped address the role of disturbance, energy availability and ecosystem size in determining food chain length. They also helped identify the structural mechanisms that cause variation in food chain length. As the same time, efforts to use stable isotopes to address food chain length pushed the development of new models and methods. While bulk stable isotope methods have been and remain very effective for addressing food chain length, compound specific techniques offer the potential to provide greater insights into the changes in food web structure that underlie variation in food chain length.