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New study from Woods Hole scientists suggests sound could help restore coral reefs

CAI | By Brian Engles

Published March 19, 2024 at 12:53 PM EDT

WHOI biologists Nadege Aoki (L) and Aran Mooney install an underwater speaker system to broadcast healthy reef sounds, off the coast of the U.S Virgin Islands.

Purring fish and snapping shrimp. Croaks and pulses from a chorus of fish. Those are some of the noises that make up the soundscape of a healthy coral reef.

Local scientists at Woods Hole Oceanographic Institution (WHOI) have been studying if these sounds could be a tool to help restore damaged reefs.

Nadège Aoki is a doctoral candidate at WHOI and lead author on a new research paper on the subject.

Her work suggests the coral larvae respond to sound when deciding where they’ll make their home.

A reef that has been degraded – whether by coral bleaching, disease, or direct human impacts – can’t support the same diversity of species and has a much quieter, less rich soundscape. A new paper from researchers at Woods Hole Oceanographic Institution shows that sound could potentially be a vital tool in the effort to restore coral reefs.

The team traveled to the U.S. Virgin Islands last summer for their research. They used speakers to play the soundscape of a healthy coral reef at the site of a degraded coral reef.

Their results found that the soundscape encouraged coral larvae to recolonize the damaged area.

WHOI said the coral “settled at rates 1.7 times (and up to 7x) higher in a degraded environment enriched by recorded sounds than at reefs where no sounds were added, underscoring the power and potential of this enrichment technique.”

Aoki said she’s hopeful this could be one way to help restore coral reefs.

“Sound alone… adding sound back to a reef, that’s not going to fix every problem on that reef. But in order to give corals a fighting chance, we need to have a lot of those tools at our disposal and we think that this is just one of them.”

She said her team saw fish gathering by the speakers too, something she hopes could lead to a positive cycle.

“If you are able to attract some of these animals to an area that maybe they aren’t going to for some reason, and if they’re able to survive and thrive there, then they are going to start producing those sounds and those cues that will attract more animals back.”

Aoki said some methods of restoring reefs can be labor intensive, where using sound could be a more passive approach.

Coral reefs are habitats for about 25% of all marine life, including corals, which are a squishy animal related to jellyfish.

Coral reefs have been degraded in part because of rising sea temperatures. Aoki said the reefs are fragile ecosystems, also vulnerable to overfishing, nutrient overflow, and several other factors.

Acoustic enrichment can be a key intervention to support imperiled reefs. Using an underwater speaker system, researchers found that broadcasting the soundscape of a healthy reef at a degraded reef caused coral larvae to settle at significantly higher rates.

WHOI has an extensive record of sound recordings from different coral reefs, including sounds from a healthy coral reef captured over a decade ago when it was in an even better state.

Aoki said the recordings used in this experiment were taken in 2013 before hurricanes and coral disease affected the habitat.

The research also included collaborating with WHOI Engineer Ben Weiss on deploying the recordings from the speakers at the right time of day, to sync up with when fish and other creatures would make the sounds that were being played into the environment.

WHOI is planning to conduct similar research in Hawaii later this year on Pacific corals.

Hear Aoki on NPR’s Morning Edition.