Tuesday 25 January 2011

Coral Bleaching

Diving sites in 7 marine national parks in the Andaman Sea and the Gulf of Thailand temporarily closed to allow coral reefs affected by bleaching to recover and regenerate.

The National Parks, Wildlife and Plant Conservation Department (DNP), Ministry of Natural Resources and Environment, has reported that coral reefs at several sites along Thailand's Andaman coast and in the Gulf of Thailand have been affected by coral bleaching - a phenomenon in which coral loses colour and becomes paler or completely white. Corals that have been exposed to environmental stress for an extended period of time are vulnerable to bleaching.

The key to stopping and reversing the situation is to immediately alleviate the environmental stress to prevent further damage to the affected reefs and create a more favourable environment that allows the coral colonies to recover and regenerate.

Hence to facilitate the speedy recovery and rehabilitation of affected areas, the DNP, on 20 January 2011, announced the temporary closure of several key diving sites in seven marine national parks. Coral bleaching at these sites extends over 80 per cent of the areas concerned.

Marine National Parks :
Hat Chao Mai Marine National Park in Trang province
Mu Ko Petra Marine National Park in Satun province
Tarutao Marine National Park
Chumphon Marine National Park
Hat Nopparattara - Mu Ko Phi Phi Marine National Park
Mu Ko Surin Marine National Park in Phang-nga province
Mu Ko Similan Marine National Park in Phang-nga province

Diving sites temporarily closed as a result of extensive coral bleaching covering over 80 per cent of the concerned areas :
Ko Chueak island
Ko Bu Lone Mai Pai island
The islands of Ko Takieng, Ko Hin Ngam, Ko Rawi, Hat Sai Khao and Ko Dong
Ko Ma Prao
Hin Klang
Ao Mae Yai bay, Ao Mangkon bay, Ao Jak bay, Ao Tao bay, Ko Torinla
Ao Fai Wap bay, Ko Payu or East of Eden

All other marine national parks remain open and are operating normally.


The following steps are being undertaken to protect the coral reefs.

To alleviate environmental stress, the DNP has introduced measures to restrict tourist traffic in marine national parks and minimize associated environmental impact.

Marine national park authorities have stepped up patrols to monitor and crack down on illegal fishing.

Agencies responsible are conducting ongoing monitoring of the coral bleaching phenomenon. Every effort is also being made to protect corals that are resistant to bleaching and speed up rehabilitation of those already damaged.

Responsible agencies are also providing updated news and information to officials, tourism-related operators, as well as Moken sea-gypsy communities, to keep all parties concerned updated on the situation and to foster cooperation in reducing environmental impact.

The DNP has also developed measures to ensure the proper management and utilization of natural resources for tourism purposes.

These include:
Stepping up the repair and maintenance of existing buoys and the installation of new buoys to prevent vessels from dropping anchor on the coral reefs;

Promoting better knowledge and understanding of responsible tourism, particularly in environmentally-sensitive areas of marine national parks;

Increasing awareness and promoting a better understanding of the coral bleaching phenomenon, and promoting increased co-operation in the preservation of natural resources and efforts to mitigate the impact of global warming on the environment.

The Tourism Authority of Thailand plays a key role in promoting increased awareness of environmentally-responsible Green Tourism through the implementation of campaigns such as the TAT's Seven Greens concept and Travel with a New Heart, for a Sustainable Thailand. Both programmes focus on the importance of fostering a 'green heart' - urging tourists to be socially responsible and environmentally aware. This complements global efforts to help protect and preserve the environment at all tourist attractions.

These initiatives are designed to enhance public awareness of the need to protect and preserve the environment and restore environmental quality. This is achieved by: raising environmental awareness; by promoting Corporate Social Responsibility (CSR); and by encouraging the active participation and support of all tourism stakeholders. These include state agencies involved in promoting tourism, private sector tourism operators and service providers, as well as public and non-governmental organizations, communities, media representatives and individual tourists — both Thai and foreign.


Changes in ocean currents and the corresponding effect on air or water temperature (such as the effects of el Niño and la Niña events, and global warming), especially higher sea temperatures, have been identified as key factors that trigger episodes of coral bleaching.

A change in ocean currents causes changes in phytoplankton and zooplankton populations, as well the amount of other nutrients present in the water. A decline in zooplankton leads to starvation.

Other reported causes of bleaching or whitening of coral reefs around the world include:

Changes in water salinity
Changes in water chemistry (in particular acidification)
The build up of carbon dioxide and methane gases
Low tide air exposure, exposure to increased ultraviolet radiation
Exposure to high light levels
Decrease in light levels
Increased or high water turbulence
Increased sedimentation (due to silt runoff), which relates to a decrease in light levels, as well as suffocation of sessile marine life
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
Pathogen infections
Cyanide fishing


The skeletal structure of hard coral is normally white. Tiny single-celled microscopic plants called zooxanthellae algae reside within the soft tissue and give live coral its colour. Corals obtain the majority of their energy and nutrients from these photosynthetic unicellular algae.

When coral is exposed to extreme environmental conditions for an extended period of time, this results in stress and causes the coral to expel the zooxanthellae algae. The expulsion of too much zooxanthellae results in coral bleaching or the loss of colour and/or the concentration of photosynthetic pigments in these organisms is diminished.

Long-term bleaching can cause the partial or total death of coral colonies. However, if the situation is not too severe or favourable conditions return within two or three weeks, affected colonies can recover their symbiotic algae and regenerate, but this process is likely to take several months or even years.

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