The predatory crown of thorns starfish is threatening Indonesia's portion of the "coral triangle," the richest area of coral reef biodiversity on the planet, scientists warned Tuesday. The starfish have been discovered in large numbers by researchers from the Wildlife Conservation Society and the Australian-based ARC Centre of Excellence for Coral Reef Studies, who surveyed reefs around Halmahera in Indonesia's Maluku Islands, a press release said.The triangle lies between Indonesia, Malaysia, the Philippines, Papua New Guinea and the Solomon Islands and contains more than half the world's reefs, considered building blocks for marine life.More than 600 species of coral -- 76 percent of those known -- and more than 3,000 plant and fish species live in the triangle's waters.Scientists said they feared the growth in numbers of the starfish was caused by poor water quality and could be an early warning of widespread reef decline."We witnessed a number of active outbreaks of this coral predator. There was little to suggest that the reefs have been much affected by climate change as yet. The threats appear far more localised," said Andrew Baird from the Centre of Excellence in the statement.The starfish feeds on coral by spreading its stomach over them and using digestive enzymes to liquify tissue.Researchers also saw evidence of blast-fishing which had occurred following communal violence in recent years."The good news is that the reef fish assemblages are still in very good shape," said the Wildlife Conservation Society's Tasrif Kartawijaya. "So these reefs have the capacity to recover if we can address the current threats."The Coral Triangle Initiative announced by six regional governments at last year's climate change conference in Bali "offers hope for the reefs in the region," the researchers said.They said however that the role of research under the initiative, which they see as crucial in working out how to respond to threats on the reef, should be made clearer.The initiative aims to establish a network of protected marine zones, to decrease wear and tear on the reefs caused by the fishing industry and to promote eco-tourism.Marine resources in the coral triangle provide a living for 120 million people and one-third of the world's tuna catches come from the area.