down of the symbiosis between corals and zooxanthellae.
When the brown zooxanthellae move out of the tissue
of the coral, they leave it a brilliant white (hence the
term bleaching). Without the zooxanthellae, the coral is
deprived of its principal source of energy. The bleached
corals begin to starve and become more susceptible to
The impact can be huge. For example, in 1998, 16
percent of the world’s coral reefs were killed by mass
coral bleaching due to warmer-than-normal sea temperatures. This global average hides the fact that some
regions fare much worse: the Western Indian Ocean, for
instance, lost 46 percent of its corals in that one year.
Over the past several decades, the incidence of mass