what is coral bleaching? stage 1 healthy coral stage 2 bleached coral polyp (coral animal) Warmer water temperatures can stress Thousands of polyps make corals, causing them to expel their up a coral colony. zooxanthellae, or bleach. zooxanthellae Bleached corals Tiny algae that live appear white, but they are inside polyp tissues. still alive and can return to They provide food for coral health if conditions improve. through photosynthesis and give the coral its color. NORMAL HIGH TIME BETWEEN STAGE 1 AND STAGE 2: days - weeks stage 3 If temperatures return recovered coral or dead coral? If conditions do not improve and temperatures to normal, the.coral could remain elevated, the prolonged stress could recover its zooxanthellae kill the coral after only a few weeks. and return to health. Dead corals are often Recovery could take weeks to . covered in algae. months, and the recovering coral . may be more susceptible to disease. RETURNS TO NORMAL REMAINS HIGH TIME BETWEEN STAGE 2 AND STAGE 3 RECOVERY: weeks - months TIME BETWEEN STAGE 2 AND STAGE 3 DEATH: days - weeks coral bleaching identification healthy healthy healthy reef unhealthy reef Boulder brain coral Boulder star coral Lettuce coral Staghorn coral paling paling / partially bleached Boulder brain coral Symmetrical brain coral Boulder star coral Boulder brain coral bleached bleached coral diseases (not bleaching) Boulder brain coral Staghorn coral Lettuce coral Smooth star coral Black Band Disease White Plague Disease dead dead White Pox Disease Yellow Band Disease Boulder brain coral Knobby brain coral Finger coral Cactus coral.