What is Coral Bleaching?
Mass bleaching of corals is now the biggest threat to the survival of coral reef ecosystems. Coral polyps harbor symbiotic algae called zooxanthellae, which provide the necessary nutrients for reef building corals to calcify reef structures. When a coral bleaches it loses its symbiotic zooxanthellae and will die within a short period of time unless it regains it symbionts. The term bleaching is used because the pigment responsible for the dazzling color of corals is due to the zooxanthellae in coral tissue, and when zooxanthellae are lost, corals appear white, or “bleached.” The actual process by which zooxanthellae are lost from coral tissue is still not well understood. Many hypotheses exist as to the cause behind coral bleaching, but the strongest evidence points to elevated sea surface temperatures as being the main catalyst. It is hypothesized that stress induced from pollution, ultraviolet radiation, and changing salinity also play a role in the extent of coral bleaching. With th
