Lengthening reef recovery times from crown-of-thorns outbreaks signal systemic degradation of the Great Barrier Reef

Repeated outbreaks of crown-of-thorns starfish Acantl~aster planci have been observed on the Great Barrier Reef (GBR) since the mid 1960s. Several authors have conlectured that long-term degradation of reef community structure is a possible consequence of such repeated outbreaks. In this paper we use the data from the Australian Institute of Marine Science's (AIMS) annual synoptic surveys (1985 to 1996) of the whole GBR as a statistical database with which to investigate this question. We use a simple mathematical model of transition between 3 reefs states-A 0 (active outbreak in progress), RE (recovering from recent outbreak), and NO (no evidence of a recent outbreak]-which we show is adequate to track the large-scale data over t ~m e .