HONG KONG, Jan 16 (Reuters) - Outbreaks of the notorious crown of thorns starfish is wreaking havoc in Asia's famous Coral Triangle, where it has destroyed large swathes of coral reefs, scientists in Indonesia and Australia said.
The predator starfish feeds on corals by spreading its stomach over them and using digestive enzymes to liquefy tissue.
The researchers found large numbers of them in Halmahera, Indonesia, which lies at the heart of the Coral Triangle. During a research trip in December, they saw a stretch of reef measuring 10 km (6.26 miles) in circumference completely wiped out.
"It's quite a stark sight. The crown of thorns choose to eat some species, like staghorn corals, the branching corals disappear and you are left with just a rubble pit," Andrew Baird of the Australia Research Council's Centre of Excellence for Coral Reef Studies and James Cook University said by telephone.
Baird said the outbreak was caused by poor water quality and could be an early warning of widespread reef decline.
"Humans are exacerbating the problem because we put too many nutrients in the water," he said, referring to water pollution caused by sewerage and agriculture fertilisers.
"There are lots of micro-algae and the larvae of the crown of thorns feed on the algae," said Baird, who was involved in the study.
The survey was carried out by the Wildlife Conservation Society and the ARC. The researchers hope to publish their findings this year.
The Coral Triangle is between the Philippines, Indonesia, Malaysia, Papua New Guinea and the Solomon Islands. It is seen as the world's richest centre of coral reef biodiversity and the genetic fountainhead for coral diversity on Australia's Great Barrier Reef, Ningaloo and other reefs in the region.
The Coral Triangle Initiative (CTI) announced at the Bali Climate Change Conference recently offered hope for the reefs but the researchers said it gave few details on how it will work.
Baird said urgent action was needed to clean up the seas and stop all destructive forms of fishing, such as dynamite and over-fishing.
"If dramatic steps are not taken, in 30 to 50 years, there will be practically no reefs, and certainly no healthy reefs in the Coral Triangle and that's just from human impacts. Destructive fishing, crown of thorns," he said.
He added that there had been three major crown of thorns outbreaks since the 1960s in the Great Barrier Reef but it recovered each time because there were always healthy populations of herbivorous fish.
"I am pretty sure there will be recovery (in the Coral Triangle) without destructive fishing or over-fishing," he said.
"When corals die, there will be algae and if there is fish, they will eat the algae and the corals will eventually come back. If there isn't any fish, then algae will grow to an extent that corals can't come back." (Editing by Jerry Norton)
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