Cyclic control in ecosystems

The theory of feedback control as a possible stabilizing mechanism has already been introduced into ecosystem analysis. One problem in the theory is the identification of the informational links by which such controls operate. Cyclic controls-for example, zero- mean sine functions added to certain exchange flows in the system-might also contribute to system stability. Their advantage is that they operate without need for information from the rest of the system. The theory of ecosystem cyclic control is presented and applied to data from an oyster reef ecosystem.