Causes of Coral Threats

Coral bleaching is a process which causes loss of vivid colours from coral organisms & turns them white due to expulsion of symbiotic zooxathellae algae.

A host of factors are responsible for coral bleaching from local to regional & global levels. It is to remember that coral bleaching occurs when coral animals & their symbiotic zooxathellae alga are separated from each other. The following factors are held responsible for coral bleaching at different levels & scales-

Global Factors:

1. Global Warming: The rise in normal temperature of seawater due to anthropogenic factors i.e. global warming. Now a days, Global warming as the most significant factor of coral bleaching causing large scale coral death.
2. El-Nino-Southern Oscillation: ENSO phenomena are responsible for coral degradation at global levels.
3. Solar Irradiance: Coral bleaching occurs due to increased solar irradiance(Photosynthetically active radiation & Ultraviolet band light.) 
4. Sedimentation: Increased sedimentation due to slit runoff resulted coral bleaching
5. Outbreak of Diseases & Epidemics: The following diseases have been identified to cause coral bleaching in different regions of seas:

Ø  Black band disease,

Ø  Coral plagues such as white plague,

Ø  Yellow band disease,

Ø  White band disease, discovered in 1996,

Ø  White pox, discovered in 1996,

Local & Regional Factors:

1. Overfishing: Destructive fishing practices & overfishing are responsible for coral degradation at local & regional levels.
2. Pollution: Pollution of sea waters caused by industrial effluents, urban sewage & oil slicks are responsible for coral degradation.
3. Mining: Mining of coral rocks for building materials are responsible for coral degradation.
4. Clearing Marine Forest: Clearing of marine forests around coral reef are responsible for coral degradation.
5. Collection of  Coral Species: Collection of coral species are also responsible for coral degradation.

‹Model of Coral Bleaching Factors: