Dying coral reef coming back to life thanks to underwater speakers

A team is helping restore the Great Barrier Reef with underwater loudspeakers that attract fish to dead coral.

Around the world, coral reefs are dying at alarming rates. Scientists attribute this phenomenon to climate change and the disappearance of ocean species. It has led researchers to adopt some interesting tactics to try and restore them.

Perhaps none are more intriguing (or more promising) than a project conducted by British and Australian researchers working in the Great Barrier Reef. The team used a series of underwater loudspeakers to simulate the sounds of a healthy reef. After the study concluded, they found that fish flocked to the areas of dead reef outfitted with speakers and even stayed there once the sounds were removed. The technique could be a promising new way to help regenerate lost reefs.

‘Dazzling Biological Soundscape’

In 2016 and 2017, over half of Australia’s Great Barrier Reef was lost due to a massive bleaching event. Scientists are still trying to figure out a reliable way of restoring it. Interestingly, enticing fish to return won’t actually reverse the damage done to the coral. Instead, it increases the reef’s chance of recovering naturally.

The study documenting the use of underwater loudspeakers was published in the journal Nature Communications. Lead author Stephen Simpson said, “Healthy coral reefs are remarkably noisy places—the crackle of snapping shrimp and the whoops and grunts of fish combine to form a dazzling biological soundscape.”

Teams played sounds simulating a healthy coral reef for 40 nights. They also used two control groups to test the method. One group used dummy speakers while the other was left untouched. Only the patches with “acoustic enrichment” had noticeably increased fish populations at the end of the experiment.

Simpson goes on to explain that these sounds attract young fish to settle in the area. Data from the study shows that portions of the reef with sounds played nearby attracted 50 percent more species of aquatic wildlife than those without sounds.

Slow Reversal

Just like it takes thousands of years for reefs to form, it will take a long time to restore them. However, the underwater sound experiment is certainly promising. Since fish play a key role in maintaining a balanced ecosystem and can stabilize a fragile reef, attracting them to the area is a huge first step.

The technique may also allow coral reefs to heal more naturally than some other processes in use today. For example, researchers in Hawaii are breeding special corals that are more resilient to increasing temperature. The acoustics method, however, lets the natural corals recover without much human interference.

Should the technique prove useful at a larger scale, it could be an important tool for ocean researchers hoping to save the world’s coral reefs.