Playing sounds of healthy reefs can pull fish towards degrading corals: Study

Young fish can be drawn to degraded reefs using loudspeakers playing the sounds of healthy coral communities, according to a study which may lead to new strategies for restoring damaged corals.

The study, published in the journal Nature Communications, described the new technique to lure fish into damaged reefs by regenerating the sounds that are lost when the coral communities are quieted by degradation.

The researchers, including those from the University of Exeter in the UK, said boosting the populations using this kind of "acoustic enrichment" can help to kick-start a natural recovery processes of the reefs, counteracting the damage seen in many coral communities around the world.

According to the study, broadcasting healthy reef sound doubled the total number of fish arriving onto experimental patches of reef habitat, and also increased the number of species present by 50 per cent.

The researchers said this diversity included species from all sections of the food web such as herbivores, plankton feeders, predatory fish eaters, and those that eat marine waste and debris.

They added that different groups of fish provide different functions on coral reefs -- meaning a diverse and abundant fish population is important for maintaining a healthy ecosystem.

"Fish are crucial for coral reefs to function as healthy ecosystems," said study lead author Tim Gordon, of the University of Exeter.

Reefs become ghostly quiet when they are degraded, as shrimps and fish disappear, but they can be restored using loudspeakers which can recreate this lost soundscape and attract young fish back again, the researchers said.

"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. Juvenile fish home in on these sounds when they're looking for a place to settle," said senior author Professor Steve Simpson, also of the University of Exeter.

By combining this method with habitat restoration, and other conservation measures, the researchers said fish communities can be rebuilt, accelerating ecosystem recovery.

"However, we still need to tackle a host of other threats including climate change, overfishing and water pollution in order to protect these fragile ecosystems," said Andy Radford, study co-author from the University of Bristol in the UK.