Since the 1950s, the world's coral reefs have been reduced by half due to factors such as global warming, overfishing, pollution, and coastal development. This dramatic decline has prompted a wide range of efforts to protect what remains — and one innovative approach to restoring these fragile habitats is harnessing the power of sound.
Coral reefs are among the most structurally complex and biodiverse marine ecosystems on Earth. They serve as multifunctional natural habitats, providing marine life with places to feed, seek shelter from predators, and reproduce, while also forming the economic and livelihood backbone of many coastal communities. Yet coral reefs are also among the ocean's most imperiled ecosystems. Since the 1950s, battered by land-based runoff pollution, overfishing, climate change, and a growing frequency of coral bleaching events — compounded by disease and ecological imbalance — the world has lost half of its coral reefs.
What many people fail to consider, however, is that "sound" also affects coral reef survival. Recent research in marine acoustics has shown that noise from shipping, underwater drilling, seismic testing, and subsea construction can damage coral reefs, inhibit coral larval settlement, increase stress in reef fish, and impair their navigation and reproductive abilities. Prolonged noise not only disrupts the natural acoustic cues that larvae rely on to find suitable habitat, but also causes long-term harm to ecosystem resilience and biodiversity.
Using the Ocean's Own Language as a Beacon to Guide Life Back to the Reef
Yet the same tool that causes harm can also be turned to healing. Sound, used wisely, can help rebuild fragile coral reef ecosystems. Experiments conducted at Lizard Island on Australia's Great Barrier Reef by the University of Exeter and the University of Bristol in the UK, together with James Cook University and the Australian Institute of Marine Science, demonstrated sound's remarkable potential.
At the time, Lizard Island's once-thriving reefs had become desolate coral graveyards following a powerful cyclone and a devastating coral bleaching event. The research team constructed miniature coral reefs from coral rubble and strategically placed underwater speakers nearby, playing recordings captured from healthy reef ecosystems. After a six-week experiment, they found that compared to reefs with no sound, the reefs near the speakers attracted twice as many juvenile fish and showed a 50% increase in species richness — demonstrating that the strategic use of sound can promote the rebuilding of reef communities.
Why can sound help marine life survive and thrive? The answer lies in the fact that healthy marine ecosystems are naturally filled with a rich and complex soundscape: the whistles and grunts of fish, the scraping of sea urchins grazing on the seafloor, the snapping of pistol shrimp, the distinctive calls of dolphins, the melodic vibrations lobsters produce with their antennae. These sounds help other organisms identify suitable habitat.
This symphony of sound acts like a beacon, drawing in small creatures searching for a home — much like the buzz of a vibrant city draws in newcomers.
"Fish are vitally important to the healthy functioning of coral reef ecosystems. Increasing fish populations in this way could help to kick-start natural recovery processes and offset the damage we're seeing on so many reefs around the world," said Tim Gordon, lead author of the study.
Coral Larval Settlement Rates Increase by 1.7 Times
Further validation of sound's potential comes from the Woods Hole Oceanographic Institution (WHOI), the largest independent ocean research institution in the United States. In 2023, the WHOI team traveled to the U.S. Virgin Islands in the Caribbean to conduct a similar study. They installed underwater speakers on three coral reefs near the island of St. John — the smallest in the group — playing recordings of healthy ecosystem sounds, and measured how many coral larvae settled on ceramic tiles resembling rock surfaces within thirty meters of the speakers.
When coral larvae are released into the water column, they drift freely with ocean currents until they find a suitable site to settle. Once they do, they fix themselves in place, and if they survive, they have the opportunity to develop into adults.
To rule out any environmental effects caused by the speakers themselves, the team installed speakers at all three sites but played healthy coral reef sounds at only one. They found that the site with active sound playback had an average coral larval settlement rate 1.7 times higher than the silent sites — and up to 7 times higher at its peak.
"If you can attract some organisms to a place they might not have gone otherwise, and they manage to survive and thrive there, then they will start producing these sounds and signals that attract more organisms back," said Nadège Aoki of WHOI. Some coral reef restoration methods require enormous amounts of manpower; using sound, she noted, is a far less labor-intensive approach.
While research confirms that "sound" shows promise as a solution for coral restoration and boosting biodiversity, a comprehensive, treat-the-root-cause approach is still needed. Reducing threats to coral survival at their source — including improving water quality and habitat conditions, curbing land-based pollution, and controlling sedimentation — is essential if the "residents" attracted by sound are to truly survive and reproduce. Nevertheless, this non-invasive restoration strategy genuinely opens up new possibilities for the rapid regeneration of damaged ecosystems. Guided by sound, marine ecosystems can heal themselves more quickly, creating a virtuous cycle.
References
- One Earth, How the power of sound can help restore marine ecosystems
- The Guardian, Playing thriving reef sounds on underwater speakers 'could save damaged corals'
- ScienceDirect, Noise pollution on coral reefs? — A yet underestimated threat to coral reef communities
- CNN, Underwater 'reef music' could help in coral restoration
- WBUR, New study from Woods Hole scientists suggests sound could help restore coral reefs
- Earth.Org, Can Soundscapes Save Coral Reefs?
※ This article is republished from the Delta Electronics Foundation's Low-Carbon Living Blog: 〈海洋噪音正在破壞珊瑚礁，但「聲音」也可能成為修復關鍵〉, co-produced with BlueTrend.
