Coral reefs may soon have new swimming visitors observing their life-rich aquatic metropolises. But that visitor isn’t a fish—or even a human. It’s an autonomous, multi-sensor survey robot. Developed by the Woods Hole Oceanographic Institution (WHOI) Reef Solutions Initiative, this new underwater surveyor uses a combination of hydrophones, high-resolution cameras, and an onboard computer to find signs of marine life hotspots. It then moves in closer for a better look, creating data-rich maps that would likely take many human divers multiple trips to produce.
The system, appropriately called the Curious Underwater Robot for Ecosystem Exploration (CUREE), does all this all by itself. Well, that’s the goal, at least. In actual testing around Joel’s Shoal in the U.S. Virgin Islands, the curious robot was able to home in on the distant crackle of shrimp, and even tailed a barracuda for more than 984 feet. That last barracuda tracking bit required some human intervention to get it back on course, but the majority of the barracuda tracking occurred totally autonomously. The findings were published this week in the journal Science Robotics.
CURREE the reef-exploring robot
Keeping tabs on coral reef’s inhabitants
Coral reefs are like a busy neighborhood or bustling bar in the ocean. Though they account for less than 0.1 percent of physical ocean space, roughly a quarter of all marine species spend some part of their lives there. But overfishing, human development, and warming ocean temperatures are putting those bustling ecosystems at risk. Because of this threat, it’s more important than ever for marine biologists to have an accurate and timely sense of what those environments look like.
Getting a clear sense of what species are where in a reef isn’t simple, though. At any given time, most of a reef is barren, with marine life typically clumping into hotspots distributed throughout the reef. Currently, researchers primarily track those hotspots with trained human divers, though that approach isn’t perfect. Our pesky lungs and limited oxygen tanks mean human divers run on a short clock. It’s also costly for research teams to properly train and equip a human diver, which limits the amount of time and frequency with which they can take a plunge.
An underwater robot could potentially solve both those problems, but it would need the right tools for the job. That’s where CUREE comes in. Engineers outfitted the robot with a variety of sensors that can detect both visual and auditory signals. The system can analyze far-off audio signals in real time to hear distant noises as subtle as fish calling out to each other. It can then triangulate that data using an onboard computer system that moves toward areas it suspects have a high chance of containing marine life. If it spots life once there, it can then use its cameras to provide more precise data about the species and their behavior.
“In some sense, they’re almost a perfect compliment for each other,” WHOI roboticist Seth McCammon said of the multiple sensor method in a statement. “Passive acoustics gives you a broad sense of the environment, while vision is short range, but is this really information-rich data stream.”
Curious robot stalks a barracuda
The team put CUREE to the test near Joel’s Shoal, a coral reef located on the coast of St. John in the U.S. Virgin Islands. In one test, the robot could accurately find and count the number of fish in a region. It was able to detect signs of fish from up to 82 feet away and then use those clues to identify life hotspots.
However, the most interesting result was CUREE’s successful barracuda tracking. Once locked on to its target, CUREE followed the apex predator for a total of nine minutes and 55 seconds, as the fish weaved its way around, looking for lunch. The tracking video in the study shows the barracuda traveling first to a hotspot and then backtracking to another spot where it had previously startled a large reef snapper. And while a human diver had to initiate the robot’s lock on the barracuda,and had to re-lock on the target several times, CUREE did most of the work on its own. The team says eight minutes and 59 seconds of the tracking was done with full autonomy.
Though this isn’t the first underwater robot, its use of multiple sensor types makes it unique because it’s eventually a jack of all trades. Researchers can, in theory at least, drop the robot in a broad area of water and let it get to work surveying.
