How underwater speakers can help save coral reefs

April 18, 2021
By Eko Diena in 

Coral is a sensitive thing, and I don’t think it’s any secret or surprise to anyone that it really doesn’t like rapid climate change. Over the last few decades coral reefs around the world, including Australia’s Great Barrier Reef have undergone a “mass coral bleaching event”. Hundreds of miles of reef around the world turned white, which may be pretty but basically means that the coral is dying.

This is a problem because reefs are the biggest living structures on the planet and they are much more important than most people realise.

Firstly, they provide a home to a massive number of species of aquatic life that just don’t live anywhere else, but they do much more. Coral reefs are one of the biggest carbon sinks on earth, they protect coastlines against extreme tides and weather, and they also are hugely important economically to many coastal communities who rely on the fishing and tourism that they bring.

The interesting thing about coral is that while it is so sensitive, it’s also pretty resilient in it’s own way, and it is possible for reefs to be restored and for the ecosystems around them to recover. But it is a now or never thing, the conditions need to improve before the coral completely dies.

Scientists around the world have been searching for solutions and one of the most strange sounding but effective has come from the joint efforts of teams of British and Australian researchers.

So, what is their method of rejuvenating the reef ecosystems? Underwater Speakers.

A healthy reef is an incredibly busy and noisy ecosystem which supports thousands of species, but as the ecosystems start to deteriorate they become much less attractive as homes and a downward spiral starts. Fish and other species realise that the habitat is not capable of supporting them and they migrate elsewhere. Bringing more life back to the reefs won’t magically restore the dead coral but it does give it a much better chance of recovering naturally.

What if we could fool these creatures into thinking that the reef is actually still a far more bustling place than it actually is though, then the current inhabitants of the reef will stick around and new ones will come to bolster their numbers and kickstart the ecosystem.

We might not think about fish making much noise but they actually do create a wide variety of different sounds. The oceans are not silent depths, there is a constant background noise. Anywhere too silent, like a damaged coral reef, is clearly seen as a not very healthy place to be and so fish will avoid it. When reef fish give birth they disperse their young out into the open water in order to increase their chances of survival. Once they mature a bit and are not in imminent danger of being eaten these young fish find themselves a suitable reef to call home.

What has happened until now is that their home reefs were loud enough to be heard and attract the next generations back, but that isn’t happening with these ghostly quiet reefs. The answer is to synthetically create the sound of a healthy reef using underwater speakers. This attracts back the young fish, which helps to restore the reef.

Marine biologists and researchers have been conducting trials of this fake reef noise in 33 patches of dead coral along the Great Barrier Reef, and the results are pretty amazing. Over the course of 40 days the number of fish in these locations doubled along with a 50% increase in the diversity of the fish species that could be found there.

This isn’t a permanent solution. It doesn’t address the underlying reasons why these ecosystems are dying out. In order to do that we need to curb global CO2 emissions and reduce the rate of global warming. Coral reefs take thousands of years to form and they will take a long time to recover from the bleaching that human driven climate change has subjected them to, but it is possible.

As Tim Gordon of the University of Exeter says “Whilst attracting more fish won’t save coral reefs on its own, new techniques like this give us more tools in the fight to save these precious and vulnerable ecosystems. From local management innovations to international political action, we need meaningful progress at all levels to paint a better future for reefs worldwide.''

We should do everything we can to give them the best chances of doing that, and the speakers are helping. If we can reduce the rate at which the coral is dying out we can use them to lure species back to these amazing reefs and help to keep them as vibrant and busy habitats.

We first published this article in the Platforma EKO newsletter Towards SustainabilityIssue 6 - December 2020.

© 2021 EKO Diena |
Green Web Foundation smiley
Hosted sustainably by S4
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram