Predator–prey interactions: is ‘ecological stoichiometry’ sufficient when good food goes bad?

The dietary value of a prey type varies with its nutritional status and hence with its C:N:P content. However, while stoichiometric differences between a heterotroph and its food must affect growth efficiency (GE), and thence trophic dynamics, other factors related to food quality may act as powerful modulators of predator–prey interactions. Thus, minor changes in prey stoichiometry can be associated with more significant changes in prey quality (production of toxins, mucus, thicker walls etc.) that may have a disproportionate effect on predation rates and GE. We term the predator response to such events, ‘stoichiometric modulations’. Often these modulations are negative, decreasing predation and assimilation rates. We suggest that due consideration should be given in the construction of multinutrient-based models of predators to the processes of prey selectivity, ingestion and digestion as functions of food quality with quantity.