Underwater acoustics could help save coral reefs

The death of coral reefs is a huge problem facing oceanologists now. An international team of scientists from the Universities of Exeter and Bristol in the UK, as well as Australia's James Cook University and the Australian Institute of Marine Science, argue that "acoustic enrichment" could be a valuable tool to help restore damaged coral reefs.

Working on an analysis of Australia's dying Great Barrier Reef, scientists set up underwater speakers playing healthy reef recordings in areas of dead coral and found twice as many fish arrived - and stayed - compared to similar areas where no sound was playing. “Fish are critical for coral reefs to function as healthy ecosystems,” said Tim Gordon of the University of Exeter. "Increasing fish populations in this way can help kick-start natural recovery processes, counteracting the damage we're seeing on many coral reefs around the world."

This new technique works by reproducing sounds that are lost when riffs degrade. “Healthy coral reefs are surprisingly noisy places: the crackle of snapping shrimp and the roar and grunt of fish form a dazzling biological soundscape. Young fish rush to these sounds when they are looking for a place to settle, said Professor Steve Simpson from the University of Exeter. “Reefs become ghostly quiet when they degrade as shrimp and fish disappear, but with speakers that restore that lost soundscape, we can attract young fish again.”

Australian Institute of Marine Science fish biologist Dr Mark Meekan added: "Of course, attracting fish to a dead reef won't automatically bring it back to life, but the recovery is reinforced by the fish that clean up the reef and make room for the corals to grow."

The study found that the transmission of healthy reef sounds doubled the total number of fish entering the experimental reef habitat sites and also increased the number of species present by 50%. This diversity included species from all sections of the food chain - herbivores, detritus feeders, planktivorous and predatory ichthyophages. Different groups of fish perform different functions on coral reefs, which means that an abundant and diverse fish population is an important factor in maintaining a healthy ecosystem.

Professor Andy Radford, University of Bristol, said: “Acoustic enrichment is a promising method of local control. Combined with habitat restoration and other conservation measures, recreating fish communities in this way can accelerate ecosystem revitalization. However, we still need to tackle many other threats, including climate change, overfishing and water pollution, to protect these fragile ecosystems.”

Mr Gordon added: “While attracting more fish will not save coral reefs on its own, new methods like this give us more tools in the fight to save these precious and vulnerable ecosystems. From innovation in local governance to international political action, significant progress is required at all levels to ensure a better future for reefs around the world.”

Source: 3dnews.ru