African dust 'killing Caribbean coral'

By Iain Haddow in Miami

Researchers in the United States say they suspect dust clouds which originate in North Africa could be to blame for a decline in the coral reefs in the Caribbean.

A team of scientists based in Florida found that bacteria contained in the dust was responsible for a sharp drop in one type of coral found in the region.

Global warming and pollution have long been thought to cause damage

Many factors are thought to be behind the gradual decline in coral reefs - the underwater ecosystems which exist in warm-water coastal areas around the world.

But drought in Africa is not traditionally one of them.

That is until a team of researchers, led by Dr Gene Shinn of the United States Geological Survey, began looking into the large dust clouds blown across the Atlantic Ocean from North Africa every year.

Bacteria

The team linked bacteria present in the dust to a sharp decline in a coral called the sea fan.

One drop coincided with a year of extreme drought in the Sahel, which caused a large increase in the amount of dust arriving in the Caribbean.

Hundreds of millions of tonnes of the dust particles are carried over the ocean every year, and Dr Shinn says the US space agency Nasa is now investigating to see whether the dust is causing respiratory problems in the Caribbean islands.

"We've learned that there's a high incidence of asthma in the Caribbean, especially among children," Dr Shinn said.

"That's the thrust of the Nasa-funded work - it's to see what's in the dust, to see if it could be causing some of the problems," he added.

Dr Shinn says the findings could change the way scientists look at coral reef systems.

Until now, global warming and pollution were considered to be mainly responsible for the world's shrinking coral reefs.

But just as acid rain was eventually shown to cause deforestation across whole continents, the dust particles in Africa could prove to be much more harmful than previously thought.