Bleaching could help corals survive.

• Position: Marine Biology - Brief Article

The phenomenon of bleaching, in which reef-building corals lose their colorful algae and become white during times of stress, may actually allow some corals to adapt to global warming and other environmental change. A study by the Wildlife Conservation Society (WCS) counters the conventional wisdom that bleaching is universally detrimental, and instead suggests that it represents a high-risk ecological strategy which allows corals to rid themselves of suboptimal algae. By doing so, they can become hosts to more-suitable algal types that increase their chances of survival during times of stress. Reef-building corals use symbiotic algae called zooxanthellae for nutrients, which in turn are housed in the protective skeletons of the corals themselves.

Andrew Baker of the WCS's Osborn Marine Labs at the New York Aquarium transplanted corals found off the coast of Panama from shallow water to deep water, and vice versa. He discovered that those transplanted upwards generally bleached, but ultimately survived, by recovering with new algae. In contrast, corals transplanted downwards did not bleach and did not change their type of algae. This resulted in suboptimal algae poorly adapted...