Detection of alternative stable states in marine communities.

During the last 20 years there have been several attempts to test the theory of alternative stable states using marine systems. The results have been mixed, and there have been conflicting interpretations of the outcomes. In an attempt to resolve some of the problems, the theory and evidence for alternative stable states are reviewed. There are several different views of what is meant by alternative stable states, and so the key elements of the theory of alternative stable states are set in the context of marine systems. Appropriate experimental designs for detecting alternative states are discussed, and recent experimental studies in coral reefs, rocky intertidal systems, soft-sediment beds, and subtidal systems are briefly reviewed. Suggestions for improving experimental designs are proposed and unresolved issues are highlighted.