REPORT Coral–macroalgal phase shifts or reef resilience: links with diversity and functional roles of herbivorous fishes on the Great Barrier Reef

Abstract Changes from coral to macroalgal dominance following disturbances to corals symbolize the global degradation of coral reefs. The development of effective conservation measures depends on understanding the cau-ses of such phase shifts. The prevailing view that coral– macroalgal phase shifts commonly occur due to insufficient grazing by fishes is based on correlation with overfishing and inferences from models and small-scale experiments rather than on long-term quantitative field studies of fish communities at affected and resilient sites. Consequently, the specific characteristics of herbivorous fish communities that most promote reef resilience under natural conditions are not known, though this information is critical for identifying vulnerable ecosystems. In this study, 11 years of field surveys recorded the development of the mos