This is what coral reefs sound like
The sounds that come from the Northern Great Barrier Reef have got quieter in the last five years, scientists at the University of Exeter have found.
The noises, which are made by sea creatures, help young fish find their way home.
Professor Steve Simpson says that without fish the reef will never recover from three years of cyclones and coral bleaching.
Follow Newsbeat on Instagram, external, Facebook, external and Twitter, external.
Listen to Newsbeat live at 12:45 and 17:45 every weekday on BBC Radio 1 and 1Xtra - if you miss us you can listen back here.