In the past decade some coral reefs have been widely
a¤ected by a phenomenon known as coral bleaching,
which involves either the mass expulsion of endosymbiotic
dinoßagellates ("zooxanthellae) or the loss of
photosynthetic pigments within individual zooxanthellae.
Bleaching often occurs following periods of warming and
doldrum conditions that result in elevated seawater temperatures
of 30 ¡-33 ¡C (Glynn 1991). Field and laboratory
studies on bleaching in corals and other symbiotic cnidarians
have established a causal link between temperature
stress, as little as 1-2 ¡C above the highest mean temperature
observed in a particular area, and bleaching