The resilience of a system refers to its ready ability to recover structure and behavior in the face of external forcing. The term has been used in limnetic ecology for two separate phenomena. In one, it refers to the hysteretic persistence of supportive capacity in the face of a managed reduction in the resource supply, giving perplexing delays in the recovery of lakes subject to treatment to reverse the symptoms of eutrophication. In the other usage, resilience is the homeostatic damping of the effects of chaotic environmental variability on community structure, certainly within quantifiable thresholds, in all aquatic ecosystems. A simple energetic model of ecosystem function is developed in order to assimilate the two types of resilience. Although provisional terms are coined to emphasize their distinction, only structural resilience describes a general property of systems and, which, moreover, assists an understanding of their health and ascendancy. Resourcing resilience owes to the separation of the loading and the growth responses in particular kinds of water body but otherwise reveals little that is not already well known. No strong case can be made for persisting with the latter usage and certainly not without the qualification.

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