Loudspeakers are bringing fish back to coral reefs

Henrietta Strickland
November 30, 2019

A team of researchers led by marine biologists at the University of Exeter in the United Kingdom set up underwater loudspeakers to play recorded sounds of healthy reefs in an effort to lure young fish to come hang out in areas where the coral had degraded.

It's hoped this discovery could help to restore damaged coral reefs.

The team saw that broadcasting healthy reef sounds increased the total number of fish arriving onto trial patches of the reef home.

Healthy corals teem with masses of vibrant and diverse life, and this is reflected in the underwater sounds and other cues that they emit into the surrounding waters.

The researchers said the recordings could be helping to lure young fish to the degraded reefs either by making fish aware that the reef is there, or by making it more likely that fish will settle there once they turn up.

The study found that twice as many fish came to the dead patches, where the loudspeakers were placed. "The first thing that strikes you is this really loud crackle sound - it is nearly like static on the radio, or some people describe it like frying bacon, and that is the sound of thousands and thousands of snapping shrimp, all clicking their claws", he said, adding that fish make noises ranging from grunts to hums, buzzes and whoops. He added that increasing fish populations through that way could help to kick-start natural recovery processes, preventing the coral reef damage around the world.

'Reefs become ghostly quiet when they are degraded as the shrimps and fish disappear but by using loudspeakers to restore this lost soundscape, we can attract young fish back again, ' said paper author and fellow Exeter marine biologist Steve Simpson.

This diversity included species from all sections of the food web - herbivores, detritivores, planktivores and predatory piscivores.

Different fish species give different roles on coral reefs, indicating that an abundant and diverse fish population is essential for maintaining a healthy ecosystem.

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

Professor Andy Radford, a co-author from the University of Bristol, said: "Acoustic enrichment is a promising technique for management on a local basis".

'If combined with habitat restoration and other conservation measures, rebuilding fish communities in this manner might accelerate ecosystem recovery'.

But, she added: "Our biggest tool in the fight for coral reefs is the 2016 Paris climate change agreement to curb global CO2 emissions, and we must continue to put pressure on governments to fulfil this agreement alongside doing our bit to reduce our own carbon footprints".

The study was published and can be read in full on the journal Nature Communications.

The popular Great Barrier Reef in Australia has been suffering due to warming water temperatures, over-fishing and pollution.

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