Published: Tue, December 03, 2019
Science | By

Healthy coral sounds lure fish back to dead reefs, researchers find

Healthy coral sounds lure fish back to dead reefs, researchers find

Extreme coral bleaching triggered by excessive warmth waves killed off 50 % of the Nice Barrier Reef, the planet's largest coral reef, in 2016 and 2017.

The researchers, including those from the University of Exeter in the United Kingdom, 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. The study, published in the journal Nature Communications, found twice as many fish came to patches of dead coral, where the sounds of healthy reefs were played compared to patches which no sound is played.

An underwater loudspeaker on a coral reef. The new technique generates sounds that are lost when reefs are quietened by degradation. In a process called "acoustic enrichment", a team of scientists from the United Kingdom and Australia, used underwater speakers playing sounds of healthy reefs near the dying ones to lure young fish toward it.

It's hoped this discovery could help to restore damaged coral reefs. This, in turn, attracted fish to the dying ecosystem, proving the researchers' hypothesis to understand that juvenile and adult fish can be enticed to explore and potentially inhabit a dying reef by playing sounds associated with that of a vibrant living reef.

In contrast to most other species, reef-dwelling parrotfish populations boom in the wake of severe coral bleaching.

At the start of fish recruitment season, when fish spawn and mature, the team built 33 experimental reef patches out of dead coral on open sand about 27 yards from the naturally occurring reef.

Over the course of six weeks, researchers from the United Kingdom and Australia played audio recordings over speakers installed underwater at dead patches found in Australia's Great Barrier Reef.


The fact that plump parrotfish were found in large numbers on both reefs indicates the feedback loop is an inherent part of reef ecology and not caused by local factors. "Juvenile fish home in on these sounds when they're looking for a place to settle", said Steve Simpson, also from the University of Exeter.

All parts of the food chain were attracted to the reefs, including herbivores, detritivores, planktivores and predatory piscivores, the researchers found.

Mr Gordon said although attracting fish to damaged reefs won't save them, using "acoustic enrichment" will give scientists the tools to help fight to save the damaged ecosystems.

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

Gordon too thinks wider "meaningful progress at all levels" is needed to "paint a better future for reefs worldwide".

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