Artificial coral ‘reef music’ attracts fish to help ecosystem

The ocean’s coral reefs are in trouble, but a solution to the problem may be “music to the ears” of marine life that rely on them – and to the scientists working to reverse threats posed by climate change and environmental damage.

That’s according to an international team of scientists who wanted to know if replacing the sounds of a healthy coral reef, which most of us never hear, would attract fish back to dying patches of reef. It turns out that the “reef music” worked in attracting and keeping fish to help with natural recovery.

“Healthy coral reefs are remarkably noisy places – the crackle of snapping shrimp and the whoops and grunts of fish combine to form a dazzling biological soundscape,” explains Dr. Steve Simpson of University of Exeter in the UK. “Juvenile fish home in on these sounds when they’re looking for a place to settle.”

The problem is that damaged reefs become ghostly quiet and the delicate food web is gone. Different groups of fish provide different functions on coral reefs and the biodiversity loss is important.

So the team got to work on “acoustic enrichment.” Simpson, along with researchers from Australia’s James Cook University and Australian Institute of Marine Science, as well as University of Bristol in the UK, published their findings in the journal Nature Communications on Friday.

They simply placed underwater loudspeakers that played recordings of healthy reef sounds in selected patches of dead coral for 40 nights, since “fish settlement” is primarily a nocturnal behavior. The area chosen, near Lizard Island Research Station in Australia, had seen two previous years of bleaching damage that affected some 60 percent of live coral.

By creating the sounds of reef life, the scientists doubled the number of fish that came to the experimental sites and increased the biodiversity of species at those sites by 50 percent.

“Maintaining healthy fish communities counteracts reef degradation, but degraded reefs smell and sound less attractive to settlement-stage fishes than their healthy states,” the paper explains. While the focus was on common damselfish populations, they noted other marine life looking for food too, and they’re sure it was the sound rather than other visual cues or the loudspeaker structures themselves.

Australian researcher Dr. Mark Meekan warns that obviously the fish are being brought back to a dead reef and it won’t spring back to life automatically, but “recovery is underpinned by fish that clean the reef and create space for corals to regrow.”

The study did not compare “reef music” sounds to see which work best, nor do the scientists suggest artificial sound can do the job by itself. They view their discovery as another tool that can be used alongside active restoration techniques and conservation measures.