PETALING JAYA - Malaysia is facing the largest loss of its coral reef population in history with the waters around the country getting warmer from next month.
Universiti Malaya coral reef ecologist Affendi Yang Amri said climate change coupled with a strong El Nino could threaten up to 90% of the country's coral reefs.
Affendi said that sea temperatures could rise 2°C above the threshold of the corals, stressing them.
"Usually if waters are at or above 31.5°C for two weeks, they will start to bleach," said Affendi.
He said the rise in temperature causes the breakdown of the symbiosis between the corals and their zooxanthellae (symbiotic algae).
It is the zooxanthellae which gives the corals their colour and is also the corals' main provider of food.
Affendi added that bleaching occurs when the corals expulse the zooxanthellae, leaving the animal tissue exposed and making its white skeleton visible.
"Corals get 90% of their food from the algae. So when the algae is expulsed, the corals begin to starve," he said.
He said that when bleached and the water temperature does not drop to 30°C or lower for another three weeks, the corals will start to die.
"The year 2010 saw the last big El Nino and many corals in Malaysia bleached and about 30% died, but we are afraid this year could be more severe.
"The warm temperature could remain for many months.
"It may be even worse than the biggest El Nino ever recorded in 1998 where 80% of the reefs in Maldives died."
According to Reef Check Malaysia, 40% of the reefs in peninsular Malaysia died in 1998.
Affendi is now hoping that it won't be as bad, and that at most, only 30% of the reefs would die. But the worst case scenario could see 90% of the reefs destroyed.
He said very little can be done at the moment to reduce the global stress on corals by El Nino and climate change, but steps can be taken to minimise local stress to give the corals a better chance of survival.
Local stresses include water pollution, plastic trash, coastal developments, sedimentation, sewage water, long fishing nets, fish bombing, physical contact from snorkelers and divers and etc.
"Zones with diverse and rare corals need to be prioritised as you want to minimise human contact in those areas," said Affendi.
"Those who take tourists diving or snorkelling must also remind them not to touch or kick the corals.
"When you know that warmer waters are about to hit, there should be no boats passing through those areas, no divers and snorkelers for a few weeks until the warm period passes."
But Affendi stressed that everything cannot be closed as that would jeopardise the livelihood of people like fishermen.
He also added that island resorts needed to step up on their sewage treatment systems as these were poor or non-existent and most of the sewage ended up in the ocean, damaging the corals.
Warmer waters until September if La Nina hits
Warmer waters will persist from next month to September if the current El Nino phenomenon is followed by La Nina.
La Nina is the condition where the central-eastern tropical Pacific Ocean is cooler than normal whereas El Nino is a warmer than normal condition in that region.
Universiti Kebangsaan Malaysia climatologist and oceanographer Prof Dr Fredolin Tangang said there is a 50% likelihood that La Nina will occur.
Dr Tangang said the current El Nino has made waters warmer by 1°C in South-East Asian seas since October last year and this is expected to continue until May or June.
"April, May and June are crucial months for the corals because that is when the ocean surface temperature is higher and additional warming may exceed the threshold temperature for corals," said Dr Tangang.
"During El Nino, winds over the region tend to be weaker and it is less cloudy, which increases the solar radiation absorbed by the surface."
"Weaker winds also means less heat is extracted from the surface of the sea, causing heat to stay on the sea surface."
He said that the water temperature around this region will likely return to normal if there is no La Nina.
But should La Nina happen in the Pacific after El Nino dies out, Dr Tangang said the warmer weather conditions will persist longer than usual in South-East Asian seas, until September or even October.
This increases the possibility of coral bleaching and dying.
Dr Tangang said this was what happened during the 1987/88 El Nino followed by 1989 La Nina and the 1997/98 El Nino which was followed by 1999 La Nina.
According to Prof Tangang, this year's El Nino is considered a strong one but weaker than the one in 1997/98.
Commercial fish population under threat if corals die
There will be fewer fish on the table if the heatwave leads to the high death toll of coral reefs.
Many commercial fishes like groupers, snappers, emperors, sweet lips and fusiliers will die in their juvenile stages if the corals die, said Universiti Malaysia Terengganu coral reef ecologist (specialising in coral fish) Yusri Yusuf.
"A lot of these fish in their juvenile stage hide in these corals," said Yusri.
"If a lot of the corals die and crumble, the fishes will be exposed to predators and will die young.
"The population of fish ready for consumption will be affected and we will feel the shortage," he said.
Universiti Malaya coral reef ecologist Affendi Yang Amri said coral reefs mostly grew along the coast where there were shallow waters and if they died, it would mean the loss of coastal protection.
He said the hard structures of the corals protected the coastal lines by breaking strong sea waves and currents before they hit the shore.
"When they die and crumble, the waves will hit the coastal areas much harder and more frequently, the coasts will erode and many resorts will be flooded," said Affendi.
"The Government may have to spend millions to build artificial breakwaters."
He added that the loss of coral reefs would also affect tourism as there would be no corals to see when tourists go diving and snorkelling.