Professor Hughes has made outstanding contributions to marine biology and coral reef ecology. He studies demography and life histories and has defined new ways of modelling population dynamics. His models have been applied in both terrestrial and marine systems, have been cited extensively and now appear in many textbooks. His quantitative analysis of community dynamics includes the first detailed account of the mechanisms underlying long-term degradation of coral reefs. Recent research on large-scale processes, including gene flow in marine organisms and regional variation in the dynamics of the Great Barrier Reef, published in Science and Nature, has been of enormous significance internationally.