There are a number of factors that might determine where you choose to make your house a home: the commute into work, the performance of the local schools, maybe the distance between you and the immediate relatives. But how many of us would select our next dwelling based on how loud the local fish are?

If you’re a larval coral, this may just be the deciding factor.

Researchers at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts have now discovered that larval coral are using the audio cues of a healthy coral reef to decide where they choose to settle down.

By broadcasting a chorus of reef activity including the grunts and purrs of feeding fish and the crackling of snapping shrimp, scientists have been able to encourage larval corals to settle and repopulate degraded coral sites, helping to revitalise them.

The study was conducted on the species known as the golfball coral larvae, marking the second time that a coral species has demonstrated a responsiveness to the sound of a healthy reef. It’s a finding that has left researchers excited for its potential as a widely applicable and easily replicable tool for reef restoration.

“Acoustic enrichment is continuing to show promise as a technique in the field and in the lab to enhance coral settlement rates,” said Nadége Aoki, a doctoral candidate at WHOI and the first author of the recently published paper in JASA Express Letters.

“There is a very limited pool of species that had any kind of acoustic work done with them so far, and this is the second one where the corals have responded to replayed sound and settled.”

The importance of the discovery cannot be overstated. Globally, coral reefs are facing a major threat, enduring the largest global bleaching event in recorded history due to the increasing impacts of climate change. These imperilled ecosystems are crucial for life around them, supporting one billion people and more than a quarter of all marine species on the planet. Many have been damaged by unsustainable fishing and tourism, coastal construction, nutrient runoff, and warming waters.

Researchers estimate that 25% of all coral reefs have been lost in the last 30 years. Projects around the globe have been undertaken to revitalise these systems. Acoustic enrichment could well become a key part of that work.

The window within which it can be used as an effective technique, however, is relatively small within coral larval development stage, with research indicating that settlement rate among them drops significantly outside of their first 36 hours in the water.

During this larval stage of its life, coral drifts or swims through the water looking for the right place to settle. To decide where it attaches to the seabed to mature into its stationary adult forms, coral larvae may rely on cues from chemicals, light, and – as now demonstrated – sounds. Damaged or degraded reefs are much quieter than a healthy reef system in which fish purr and grunt as they feed or fend off predators and shrimp snap and crackle.

By emulating these sounds through an underwater broadcast system, Aoki and her team of researchers have been able to encourage the larvae of the golfball coral species to settle in damaged and degraded areas.

But golfball coral have a relatively short window of viability in their larval stage and lack the resources to float around for weeks searching for the ideal spot. Typically, they want to settle within the first eight to 36 hours of being released into the water. The acoustic cues are therefore most effective while the larvae “have the resources to be picky” finding that once they ‘run out of time’ they are likely to settle ‘just about anywhere.’

“We’re getting at some of the nuances of coral biology,” said Aoki. “There’s a huge range of reproductive strategies that corals use and different species have different larval periods. We’re opening up this broad realm of questions about how responsiveness to sound will vary between species.”

The work has also demonstrated that corals will respond to auditory cues in tanks where attractive environments can be trickier to get right. While there isn’t likely to be a single solution that works for every coral species in every part of the world, researchers hope that acoustic enrichment – applied with an understanding of the local ecology and coral biology – will prove to be an effective tool for coral restoration.

“Finding a second species settling in response to sound shows this isn’t just a one-off and maybe we can really scale this up,” said Aran Mooney, a marine biologist at WHOI and senior author of the paper. “But we can’t just throw a speaker over the side of a boat and think it’s going to work. We have to know the system and it has to be integrated with other conservation and restoration efforts.”

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