WARMER WATERS, DISEASE THREATEN DEEP SEA CORAL

James Randerson, science correspondent
Saturday July 21, 2007
The Guardian

A mystery disease is destroying rare coral populations around the UK coastline, according to marine biologists. The disease, which has similarities with infections that have decimated tropical reefs, is the first ever identified in cold water corals and the first to be seen in British waters.

The researchers have established in laboratory experiments that it is caused by a bacterial infection which seems to be prompted by increases in water temperature. That has fuelled speculation that the recent spate of outbreaks is due to rises in the sea temperature around Britain due to climate change.

"Many people know about tropical coral reefs, but are completely unaware that British waters contain a huge diversity of life, including these corals," said Jason Hall-Spencer at the University of Plymouth. "Diseases increasingly affect tropical corals and this is the first record of disease affecting cold-water corals."

He first heard reports of the disease occurring around Lundy island, off north Devon, from divers in 2002. They were seeing pink sea fans (a coral species, Eunicella verrucosa, that forms colonies up to 80cm high and a metre across), that had lost their colour and were covered in other marine organisms such as barnacles and seaweed. "When you look more carefully while you are diving you see the pink tissue on the outside has started to slough away, exposing the hard skeleton," he said. Between 2003 and 2006 he and his team surveyed 13 sites known to biologists as strongholds for the species. His team found evidence of the disease at seven of the sites. Damage to the pink sea fan is significant because it is already listed as "vulnerable" by the international conservation Red List. It is also one of the few marine species protected under the Wildlife and Countryside Act 1981.

"They are special because ... they create habitats for other living organisms. They form quite dense communities, a bit like a forest, and that provides hiding places and feeding places for lots of other different organisms," said Brian Zimmerman, a coral expert at London Zoo who is not part of Dr Hall-Spencer's group. The team, which reports its work in the journal Diseases of Aquatic Organisms this month, also identified the bacteria that cause the coral's demise. On their own the bacteria are harmless, but as the water temperature is increased the corals become more vulnerable to attack.