Coral reefs around the world are under siege - FACT. Threats from over-fishing, urban coastal encroachment and rising sea temperatures are destroying sensitive corals and devastating the marine life they support.

According to The United Nations, in the last four years ten percent of the world's reefs have died, and nearly a quarter are sick and suffering. Think about that for a second. More than half of the living reefs are seriously threatened, and scientists estimate that if today's trends continue mankind will cause the irreversible loss of reef formations and related fish species within 40 years.

Fortunately, there is a growing dedicated global effort to reversing this decline and to finding new - and sustainable - ways to manage the last of Earth's remaining coral reefs. Here are some reef facts for you to consider:

• Coral reefs are home to more than 25 percent of all marine life - yet occupy less than one percent of the ocean floors.

• Coral reefs have been around 100 million years and are the largest living structures on earth. Australia's Great Barrier Reef is more than 2,000 km long and can be seen from outer space.

• Scientists have found as many as 3,000 different species living on one reef in Indonesia.

• Coral reefs protect shorelines from erosion and storm damage. Without reefs, many islands, in the Banda Sea for example, and low lying mainland would be underwater.

• Coral reefs are a tremendous medical resource, providing chemical compounds used in antihistamines, antibiotics and other medications for illnesses ranging from asthma to leukaemia and heart disease. Indeed, more than half of all new cancer drug research focuses on marine organisms.

• More than 350 million people worldwide depend on corals for food and survival.

• Corals are animals-not rocks or plants-and they come in two types, hard and soft.

• Some deep water corals grow very slowly-as little as 30 cm in 1,000 years, while some shallow water corals may grow up to 15 cm per year.

• Corals need very specific conditions to survive - a narrow range of water temperatures, access to sunlight and low pollution levels.

• More than 14 million hectares/35 million acres of coral reefs have been destroyed by human activity - 10 percent of the world's reefs have died during the last four years alone, a number that could rise to 20-30 percent by 2010 without immediate and decisive action to preserve and sustain those that are left.

There are a number of reef threats one has to be aware of. These include the following:

• Global warming is perhaps the most serious threat to healthy coral reefs. Scientists expect sea temperatures to rise several degrees in the next 20 years. When water temperatures get too high, corals turn white or bleach and eventually die.

• More than 75 percent of the earth's people live in coastal areas, bringing to pristine coral reefs such threats as over-fishing, pollution and direct physical damage. Asia's population is expected to double in the next 25 years - the threat of further reef over-exploitation grows as well.

• Fishing with explosives, as in Burma and Thailand, and poisons in Indonesia not only kills fish but reefs as well. In the Philippines, about 180,000 kg of cyanide is dumped into the ocean each year, badly degrading local reefs.

• Sedimentation caused by run-off from poorly planned and managed construction, logging or mining, muddy reef waters with silt, cutting them off from the sunlight they need to survive. There are now no coastal reefs remaining in Phuket.

• Water pollution from sewage, oil and other chemicals can poison coral reefs. Ordinary rubbish dumped in the ocean can also kill coral reef life - plastic bags have been found in the stomachs of reef fish and turtles. Both these degrading activities are taking place in Phi Phi Islands.

• Coastal development, which involves altering coastline habitats and the cutting of mangrove forests, also threatens the ocean's fragile ecosystem. The small group of Thailand Dugongs is under serious threat at Koh Turatao due to this very problem.

About The Author

Sheldon Hey is the founder of Dive The World (http://www.DiveTheWorldThailand.com) and has been an passionate scuba diving professional for many years. Sheldon and the Dive The World Team would love to share their experience with you to ensure your next diving trip meets all your expectations.

Sheldon@Dive-The-World.com