Coral Bleaching - Triggers

Triggers

Coral bleaching is a generalized stress response of corals and can be caused by a number of biotic and abiotic factors, including:

• increased (most commonly), or reduced water temperatures
• starvation caused by a decline in zooplankton levels as a result of overfishing.
• increased solar irradiance (photosynthetically active radiation and ultraviolet band light)
• changes in water chemistry (in particular acidification)
• increased sedimentation (due to silt runoff)
• bacterial infections
• changes in salinity
• herbicides
• low tide and exposure
• cyanide fishing
• elevated sea levels due to global warming (Watson)

While most of these triggers may result in localized bleaching events (tens to hundreds of kilometers), mass coral bleaching events occur at a regional or global scale and are triggered by periods of elevated thermal stress resulting from increased sea surface temperatures.