Coral Bleaching is a response to stress, often but not always an increase in temperature. When under stress corals expel the symbiotic algae living in their tissues, causing them to turn white and appear "bleached." Most corals cannot survive without these algae, known as zooxanthellae, since they rely on them for much of their nutrients. Recently scientists have reported that bleaching has been found on 93% of reefs that are a part of the Great Barrier Reef system.

symbiotic- a relationship between two organisms that benefits both

Written by Science Educator, Charlton Brownell