A few years ago, climate change caused what is known as a “mass coral bleaching event”; since then it has gone downhill, making restoring coral reefs an increasingly urgent task. From 2014-2017, unusually warm waters affected over 70% of the coral reefs worldwide. As a result, areas like the Great Barrier Reef experienced hundreds of miles of coral bleach damage.

Although it may take years for the ecosystems to fully recover, restoring coral reefs is certainly possible. However, it is vital for their living conditions to improve before the coral dies. Fortunately, scientists from the University of Exeter have discovered a method to expedite the recovery of reef ecosystems: using sound.

Coral Reefs Are Too Quiet: A Tall Barrier To Overcome In Restoring Coral Reefs

One of the biggest problems dying reefs face is the lack of animal inhabitants. In the past, reef ecosystems supported thousands of species. However, with a degrading ecosystem, these areas are not as appealing as they once were.

In a healthy reef, the large biodiversity of creatures creates an orchestra of noises. In a way, they are bustling places.

According to Tim Gordon, the author of the latest study from the University of Exeter, “the first thing that strikes you is this really loud crackle sound”.

He continues by noting that “it is almost like static on the radio, or some people describe it like frying bacon, and that is the sound of thousands and thousands of snapping shrimp, all clicking their claws”.

Apparently, fish can produce an array of noises like buzzes, grunts, and hums.

Overall, there is always a constant background noise hidden in healthy parts of the ocean. However, a non-healthy reef has very few fish sounds as a result of a low population. Currently, these damaged coral reefs emit an eerie quietness that is deterring fish away.

Reef fish often disperse their young away from reefs and into open water. This is to increase their offsprings’ chances of survival. Once matured enough, these fish are responsible for finding a suitable reef to live in.

If matured fishes are unable to hear their home reef, the possibility of them returning is very slim.

Underwater Speakers Attracting Fish Back

Fortunately, with the use of underwater speakers, scientists are now able to lure juvenile fishes back to reefs. In return, fish can help in restoring coral reefs and recycle essential nutrients.

Through the collaboration of researchers and marine biologists at the University of Exeter in the UK, the team installed multiple speakers across the oceanic floor. By playing prerecorded sounds of healthy reefs, their hopes were to entice young fish to return to areas that had degraded.

As noted in the journal Nature Communications, the experiment utilized 33 test patches of dead coral rubble across Australia’s northern Great Barrier Reef. To ensure the collection of unbiased data, the team set up several sites with either active speakers, dummy speakers, or no speakers.

At 11 of the test patches, the team installed active speakers that mimicked the noises of a healthy reef. For 40 days, the sounds continuously played throughout the night. This is due to the fact that fishes are most active near reefs from dusk until dawn.

After the 40 day experiment, the team deconstructed the dead coral rubble and revealed the reefs’ progress. There is no doubt that their results proved their hypothesis. Overall, playing healthy reef noises doubled the total of number of fish at these locations. Not to mention, the sites experienced a 50% increase of fish species diversity.

The Need For Restoring Coral Reefs

Coral reefs are an essential part of our world. Not only do they provide homes for billions of sea creatures, but they support the livelihood of humans across the globe. Worldwide, over half a billion people depend on reefs. From food to income to recreation, it is essential to protect reefs to maintain a balanced economy.

While fighting for the protection reefs, Gordon stressed the importance of tackling the original source of damage. Although the use of underwater speakers is improving current situations, Gordon notes that “it is not a way of solving the coral reef crisis [or] a way of bringing back a whole reef to life on its own”. Instead, the permanent solution lies in continuous efforts in areas such as curbing global CO2 emissions.