Figure 1. Dynamic model of an ecosystem shifting between alternative states (regimes 1 and 2).

In regime 1, the consumer is controlled by a top predator (top-down control) and the resource is controlled by nutrient availability (bottom-up), whereas in regime 2, the resource is controlled by the consumer (top-down) and the consumer is controlled by resource availability (bottom-up). The model is redrawn from [22] based on a marine ecosystem with four trophic levels, although this could be applied to ecosystems with a different number of trophic levels, in both terrestrial and marine environments.