Fig. 1. Bleached and unbleached corals at Great Keppel Island on the Southern Great Barrier Reef in January 2002. The coral on the left appears brown and healthy whereas the colonies on the right are partially (lower right) and fully (upper right) bleached. This differential bleaching response between different coral species is commonly observed and not fully understood. Photograph courtesy of O. Hoegh-Guldberg, Centre for Marine Studies, University of Queensland.