Coral bleaching is the loss of color of corals, due to an environmental stress-induced expulsion of symbiotic unicellular algae or due to the loss of pigmentation within the algae. The release of the symbiotic colored algae normally living within coral animals, which occurs when coral animals are stressed and makes the coral appear whites. Environmental stress such as global warming, increased water temperature, pollution or sedimentation. There are three main causes for coral bleaching; primary cause is high water temperature.
- increase of 1.5˚ - 2˚ for 6 to 8 weeks = can trigger bleaching
- same increase › 8 weeks = corals begin to die
- affects reefs at regional to global scale (global warming huge cause)
- severe and wide spread bleaching can occur known as mass-bleaching event
Second main cause is disease. Disease in coral usually at local scale. Infectious bacteria attacking the symbiotic algae. One such agent has been later identified as Vibrio shiloi. The pathogen is infectious only during warm periods; therefore, global warming would increase the occurrence of conditions that promote the spread of infection.
Third main cause is pollutants. It is usually at local scale either. Chemical runoff (fertilizers, industrial waste etc.) into the water can cause the coral to expel the algae.
image taken from www.stormcenter.com
- increase of 1.5˚ - 2˚ for 6 to 8 weeks = can trigger bleaching
- same increase › 8 weeks = corals begin to die
- affects reefs at regional to global scale (global warming huge cause)
- severe and wide spread bleaching can occur known as mass-bleaching event
Second main cause is disease. Disease in coral usually at local scale. Infectious bacteria attacking the symbiotic algae. One such agent has been later identified as Vibrio shiloi. The pathogen is infectious only during warm periods; therefore, global warming would increase the occurrence of conditions that promote the spread of infection.
Third main cause is pollutants. It is usually at local scale either. Chemical runoff (fertilizers, industrial waste etc.) into the water can cause the coral to expel the algae.
image taken from www.stormcenter.com
