Twenty years ago, divers in Dubai could swim through coral gardens teeming with brightly-coloured fish and sea turtles. Today, says marine biologist Tom Goreau, dead reefs stand like gravestones for an underwater ghost town.

In the UAE, some of the world's glitziest building projects, such as the opulent homes on one of Dubai's manmade palm-shaped islands, sit on these coral cemeteries.

'The best reefs were simply dumped on,' Goreau, who heads the US-based Global Coral Reef Alliance, was quoted as saying in a report in our sister newspaper Gulf Daily News.

'Those areas that were supposed to have been protected areas were peddled off to developers. They're gone, wiped out.'

Surviving reefs contend with desalination plants, necessary for supplying fresh water to the desert countries along the Gulf coast.

The plants spew hot brine and chemicals into the sea, warming their surrounding waters and increasing salinity.

Twenty per cent of the world's reefs are damaged beyond repair. Scientists are uncertain about what proportion of the Gulf's reefs have died. A Kuwaiti diving team recently reported that 90pc of the coral off Kuwait's coast was dead or severely stressed. Qatar has also seen dramatic coral death.

Scientists worry pollution and construction continues at a rate that could kill Gulf reefs, which had proven resistant to rising temperatures and increased ocean salinity.

Coral reefs support a third of the Gulf's fish populations - and local economies.

'We don't protect corals just because they're beautiful,' said Rita Bento, marine biologist for the Emirates Diving Association.

'Corals are a source of food, fishermen go there to fish. We have a lot to gain from them.'

The UAE is growing more aware of climate threats, adding government environment advisers to approve coastal construction plans. Abu Dhabi is sponsoring the development of what it calls the first zero-emissions city, Masdar.

Overfishing is another problem, but scientists say damage to reefs, where fish feed and breed, may also be behind what Dubai fishermen say is a 20 per cent drop in their catch since 1990.

'It's not like it was years back. There were a lot of fish and it was so cheap,' said one fisherman, dumping baskets of brightly striped fish off his tiny motor boat for market.

Hamad Al Roomy, general manager of the Dubai Fishermen's Co-operative, says in 2008 Gulf waters were invaded by a red tide, or harmful algae bloom, often caused by a sudden temperature change.

'It hit like a nuclear bomb that kills everything around it,' he said.

'You could see the red tide coming. The fish were trying to escape. They'd just jump right onto the beach.'

Red tides soak up oxygen, suffocating fish. Hundreds of thousands of fish were killed in a single day. Months later, residual algae killed swathes of coral on the UAE's east coast.

Some scientists think red tides could become more common due to the warming of Gulf seawater, which is occurring faster than anywhere else in the world, probably accelerated by pollution.

Pollutants can take years to be flushed out of the Gulf, which is almost entirely sealed from the wider ocean except at the narrow Strait of Hormuz, through which passes 40 per cent of the world's seaborne oil.

But scientists say it is not the amount of coral death in the Gulf that surprises them, it's how much has survived.

Most corals cannot live in temperatures above 28 C, says Thabit Abdelsalaam, of the Abu Dhabi government's Environmental Agency.

'Our corals live and survive at 37 degrees centigrade,' he said. 'That could be a source of hope around the world.'

The Gulf differs from most other seas where coral is found because at only 20,000 years old, it is an evolutionary newcomer.

'Corals haven't had time to adapt into new species... but here, they've already adapted to high temperatures,' says Keith Wilson of the Emirates Marine Environmental Group.