A team of scientists says that playing sounds underwatercan get fish to return to areas with severely damaged coral reefs.In an experiment, they found fish returnedafter hearing recordings of the sounds of a healthy ocean reef.The international team included scientistsfrom the British universities of Exeter and Bristol,as well as Australia's James Cook University.The research results were reported in the publication Nature Communications.The scientists placed underwater speakers in areaswhere coral had been dying in Australia's northern Great Barrier Reef.They played the sounds over a period of about a six weeks in 2017 and studied the results.The team reported that twice as many fish arrived in areaswhere the sounds of healthy coral were played.The sounds also led to a 50 percent increase in the number ofspecies present in the area, the researchers found.Among the arriving fish were species that feed on all major food sources.The researchers noted the importance of having many different kinds of fish return to the area.Different species of fish perform many activitiesthat support the ocean environment and sea life."Damaged reefs have a higher chance of recoveryif they have healthy fish populations," the scientists wrote in the report.Steve Simpson is a professor at the University of Exeter who helped lead the research.He said in a statement that "healthy coral reefs are remarkably noisy places."They contain the sounds of many kinds of shrimp, fish and other sea creatures.Young fish listen for these sounds when they are looking for a place to settle, Simpson said.He added that reefs "become ghostly quiet" when they suffer destructionthat is usually related to human-caused pollution.Coral damage can cause unappealing smells and sounds that drive shrimp and fish away.But the experiment suggested that the use of underwater loudspeakerswas an effective way to get young fish to come back.Mark Meekan is a fish biologist with the Australian Institute of Marine Science.He said in a statement that the return of these fish is the first stepto seeing major improvements in reef health."Recovery is underpinned by fish that clean the reef and create space for corals to regrow," he said.Tim Gordon was another member of the research team from the University of Exeter.He says he believes sound can be used to bring back dead coralin areas suffering major destruction in oceans across the world."Boosting fish populations in this way could help to kick-start natural recovery processes,counteracting the damage we're seeing on many coral reefs around the world," Gordon said.University of Bristol professor Andy Radford said the underwater soundsare a promising way to fight coral reef damage at the local community level.But he noted that other threats need to be reduced as well.These include climate change, pollution and overfishing.Gordon added, "From local management innovations to international political action,we need meaningful progress at all levels to paint a better future for reefs worldwide."