Elements of ecology and evolution

Ecological stoichiometry (ES) is the study of the balance of energy and multiple chemical elements in ecological interactions (Sterner and Elser 2002). This field has many roots, but most proximally it has emerged from studies of trophic interactions in freshwater plankton and focused primarily on the ratio of carbon to phosphorus (C:P) in the freshwater cladoceran Daphnia and that of their phytoplankton food. Two impor-tant findings emerged from these seminal studies some 15 years ago: first, the observation that release of key nutrients like nitrogen (N) and P depended, in a predictable manner, on C:N:P ratios in the zooplankton consumer relative to that in its phytoplankton food with effects on phytoplankton nutrient limitation (Elser et al. 1988, Sterner et al. 1992) and, second, the discovery tha