If This Reef Could Talk

SCUBA gear—the wetsuit, mask, and flippers—are key tools for ocean scientists who study what lies beneath the surface.

According to Aaron Rice, an ichthyologist at the K. Lisa Yang Center for Conservation Bioacoustics at the Cornell Lab and a diver himself, “Most SCUBA diving bottoms out at 100–150 feet, so studying deep reefs can be quite a challenge.”

At the other extreme lie deep-sea submersibles: pressurized vehicles that take adventurers to ocean depths of 1,000 feet and beyond. But what about oceanic regions between 150 and 1,000 feet? This in-between depth is commonly called deep reefs—and it’s also a dark spot in terms of our understanding.

As the Lab broadens its scope to protect biodiversity beyond birds, we’re seeing more and more of these dark spots on the map. Places people haven’t gone and in some cases can’t go. As Lab executive director Ian Owens says, “If we can’t measure it, we can’t protect it.” So how can we shine a light on those places and assess their biological importance?

Matt Duggan, a PhD student working with Aaron at the Lab, found a way. Using low-cost sound recorders, 360-degree cameras, and AI modeling, Matt has been gathering “spatial audio” in order to map biodiversity in the ocean’s 3D environment.

“Spatial audio allows you to enter an environment you can’t dive to,” Matt says, “which is important because biodiversity at that depth is indicative of how we’re treating the environment of the shallows—and it’s the shallows where we find so many species of fish humans rely on for sustenance.”

The Lab is internationally recognized for marine bioacoustics innovation—but how do we make the move into full-scale ocean conservation? And how do we get someone like Matt into the deep reefs?

The Beginning of a Beautiful Friendship

Carole Baldwin is the director of the Smithsonian’s Deep Reef Observation Project. Carole knows a lot about fish and she’s been exploring coral reefs off the coast of Curaçao for a long time—13 years and counting. “I was writing a lot of grant proposals and was ready to leave,” she says. “Then Matt showed up.”

After getting connected through one of Matt’s professors at Cornell, Carole was so impressed by his enthusiasm, creativity, and command of machine learning that she brought him to Curaçao. Their primary goal? Devise the right metrics to map ocean diversity and determine where ocean conservation should be focused.

Matt’s and Aaron’s spatial audio is paving the way. As Carole noted, “I was astounded to learn that 75% of fish families—maybe even more—talk.”

Because fish make sound internally, even direct observation can’t always tell you which fish are making which sounds. Using 360-degree cameras paired with audio, Matt and Aaron began to catalog fish species, sound by sound.

Eventually, Matt, Aaron, and other scientists will need to have a reliable way to match the sounds they capture to species without direct observation. “Matt and Aaron basically have to create the reference library for fish species sounds,” explains Carole.

As of now, only 5% of the world’s oceans have been studied, so Matt and Aaron’s approach to cataloging sounds opens up the potential to do oceanic population studies all over the globe.

But that’s one thing the Lab is uncommonly good at: building a vast reference library of sounds found in nature. As Aaron says, “The Macaulay Library at the Cornell Lab already hosts the largest repository of fish sounds in the world, but Matt and I have been trying to add to it and expand it.”

An Early Detection System for Ocean Health

Once they have a robust reference library of fish sounds in hand, Matt and team will no longer need 360-degree cameras and can instead deploy low-cost, passive audio recorders at scale. As Aaron says, “Reefs may be gone by 2050. So we really have an opportunity to bring this cutting-edge technology to the global-scale problem of declining coral reefs.”

Just like birds, coral reefs are uncanny indicators of overall ecological health. That’s why the plan is to replicate the Curaçao approach elsewhere, “catch ecosystems that are starting to deteriorate early on,” as Carole puts it, and ultimately set up a global detection system for ocean health.

Matt has just been awarded a Fulbright fellowship to return to Curaçao and continue his research. “I’ll be staying in the captain’s quarters in the sister ship of the Calypso, Jacques Cousteau’s research vessel.”

Part of Matt’s mission during his Fulbright is to empower local marine biologists to do this kind of research and own the process. “Often they are tuned into what the important questions are.” Matt and a team of local scientists and engineers will be installing a 90-ton glass-walled classroom and restaurant 40 feet below the ocean surface. The director of the research center told Matt, “It’s really like a silent movie down here!” Matt’s response: “Why don’t we integrate spatial audio?” This means that someone in a wheelchair can watch a pristine coral reef 40 feet below the surface and listen to the community of fish click, pop, grumble, and boom.

“Birds are charismatic because we can see them communicating,” Matt says. “And yet, the majority of the population has never seen a fish talk to another fish.”

Thirteen years in, Carole’s project is the longest-running deep reef study in the world—and it’s the only one with this degree of community outreach and local capacity building. Of course, scientists and organizations the world over are monitoring ocean chemistry and temperature. But we don’t yet know how those changes affect biodiversity—and, as Carole says, “there’s no coordination across reference libraries or tech.”

“We need a leader in this effort,” she adds, “someone who can head a global monitoring program for deep reefs through underwater acoustics. The Cornell Lab of Ornithology is who I want at the table.”