What is coral bleaching and how does it affect reefs?
Coral bleaching happens when corals are stressed. Essentially they lose the symbiotic algae that live inside them, and because the algae give them most of their color, they turn white. (The coral skeleton is white, and becomes visible through the thin transparent tissue.) Bleaching can happen in response to many different stresses, such as sedimentation, pollution, predation scars, and others, but it has really been noticed because of the widespread increase in sea temperature that is stressing corals and causing bleaching around the world. The problem is that when the stress is too great, bleaching cannot provide adequate protection and the corals then die. Corals support the rock structure of reefs and help them keep pace with erosion, so if corals bleach and die, the reefs slowly erode away. This results in a much simpler system, like a rocky reef, and as a result the reefs lose their complexity and diversity. Global warming and El Niños reinforce the damage caused by coral bleachin
