In another study, published in the journal Science, international researchers surveyed more than 150 coral reefs from four countries in the Asia-Pacific region between 2011 and 2014. More than 11 billion items of plastic alone were found on a third of coral reefs surveyed. This figure is predicted to increase to more than 15 billion by 2025. Plastic raises by 20-fold the risk of disease outbreaks on coral reefs, according to research. Plastic bags, bottles and rice sacks were among the items found. "Plastic is one of the biggest threats in the ocean at the moment, I would say, apart from climate change," said Dr Joleah Lamb of Cornell University in Ithaca, USA. More than 275 million people rely on coral reefs for food, coastal protection, tourism income, and cultural importance.