The Board of Trustees of
Sabah Parks

Coral Bleaching

Coral bleaching is the loss of intracellular endosymbionts (Symbiodinium, also known as zooxanthellae) through either expulsion or loss of algal pigmentation. The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with unicellular flagellate protozoa that are photosynthetic and live within their tissues. Zooxanthellae give coral its coloration, with the specific color depending on the particular clade. Under stress, corals may expel their zooxanthellae, which leads to a lighter or completely white appearance, hence the term "bleached".

The skeletal structure of hard corals are normally white, but due to zooxanthellae algae, which are tiny plants called dinoflagellates (single-celled microscopic organisms which belong to the Protista kingdom) that reside within the soft tissues of corals, they have color. These microalgae are photosynthetic, and their relationship with some corals, as well as other marine life such as Tridanid clams, nudibranchs, some sponges and even jellyfishes, is an example of endosymbiosis.

A change in ocean currents, which relates to changes in phytoplankton and zooplankton populations, as well the amount of other nutrients present in the water.
1. Increase/decrease in water temperatures.
2. Increase/decrease in water salinity.
3. Increase/decrease in air temperatures.
4. Build up of carbon dioxide and methane gases.
5. Exposure to increased ultraviolet radiation
6. Exposure to high light levels.
7. Increased or high water turbulence.
8. Decrease in light levels.
9. Sedimentation, which relates to a decrease in light levels, as well as suffocation of sessile marine life.
10. Pollution, which is not limited to the depositing of sediment from soil erosion, chemicals such as nitrite, nitrate, ammonia, phosphate, as well as other detrimental contaminants into the sea via river run-off and drain pipes.

However, the most of the marine park is less affected by coral bleaching problem. It is estimated that around 10 per cent.