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South Florida Aquatic Environments

Coral Reefs



CORAL BLEACHING
Coral Bleaching
courtesy OAR/National Undersea Research Program
Coral Bleaching


Coral diseases:

Coral Bleaching

  • Symptoms:
    • Loss of symbiotic algae leaves translucent coral tissue
    • Colonies appear white from the underlying skeleton

  • Cause:
    • Bleaching is believed to be caused by stressful environmental conditions


Coral bleaching occurs through the loss of the symbiotic algae found in living coral tissue. These zooxanthellae are responsible for giving healthy coral a brownish or greenish coloration. When these algae are lost, the white coloration of the underlying skeleton is visible through the translucent coral tissue. Partial bleaching may occur, resulting in only partial loss of zooxanthellae from the colony, as well as total bleaching when the entire coral colony appears bleach white.

Coral Bleaching in Florida Waters
courtesy Florida Keys National Marine Sanctuary
Florida Coral Reef Scene


This coral disease was first reported in the late 1800's, however since 1980 extensive outbreaks affecting numerous species have been documented. The affects of bleaching vary greatly among species of corals as well as between individuals within the same species. Bleaching is believed to be a response to stressful environmental conditions. It is attributed to increases in ultraviolet radiation, extreme temperatures and salinities, and high levels of turbidity and sedimentation. Loss of zooxanthellae affects growth rates and overall health of the coral host.