Great Barrier Reef

How Scientists are Using Sound Waves to Repopulate the Great Barrier Reef

Climate change is transforming the Great Barrier Reef, turning a once lively and colorful underwater ecosystem into a massive coral graveyard. Already, about 89% of the reef is dead or dying, putting the future of countless species of underwater life in jeopardy. Once teeming with life, large sections of the reef are now eerily quiet, which scientists believe led fish to abandon this habitat. In an attempt to revitalize this dying ecosystem, scientists have installed loudspeakers in various areas of the reef to make them sound as though they are healthy. Scientists have observed that reefs that sound lively attract fish to return to these habitats, paving the way for a potential future project to restore, at least in part, the once-lively and diverse ecosystem of the Great Barrier Reef.

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Using a process they call “acoustic enrichment,” which they described in a report published by Nature, scientists played noises including “the crackle of snapping shrimp and the whoops and grunts of fish” via a network of underwater loudspeakers. The scientists observed that twice as many fish arrived, and stayed, in areas of the reef that sounded lively compared to equivalent areas where no sounds were played. As the presence of fish is necessary for sustaining the ecosystems of coral reefs, scientists hope that attracting fish back to the Great Barrier Reef will help to kickstart other life in the region, potentially undoing some of the disastrous effects of rising ocean temperature levels. In other words, scientists hope that making coral reefs seem to be teeming with life will attract fish, beginning a natural recovery process.

As the field experiment lasted only six weeks, scientists have not yet had the opportunity to determine to what extent the repopulation of coral reefs impacts the larger surrounding ecosystem. However, the success of the experiment thus far has provided hope that interventions using science and technology can mitigate the damage of ecological collapse caused by climate change and other effects of human activity. That being said, while acoustic enrichment has proven to be an effective strategy for attracting fish, a number of threats to the Great Barrier Reef as well as the larger underwater ecosystem remain and will have to be accounted for to ensure the ongoing health of the ocean. These threats include climate change, overfishing, and water pollution.

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The span of time during which scientists observed the reef was too short for the fish to start breeding, and as of yet it’s unclear whether the fish will stay in this habitat long enough to spawn multiple generations of animals and to revitalize the surrounding coral. Coral depends upon the natural byproducts created by fish in order to survive, as they work as vitamin filters that allow the reefs to absorb nutrients. And as up to 85% of the oxygen in the atmosphere comes from the ocean, the health of underwater reefs also directly impacts life above land.

While large swaths of the Great Barrier Reef are entirely dead, a small percentage of the reef remains alive, albeit less populated with life than they used to be. Other projects to revitalize sections of the reef have also been conducted, with varying degrees of success. For example, scientists working for the Mote Marine Laboratory grew small pieces of reef in the laboratory and implanted these pieces alongside compromised sections of reef, which helped to regrow coral in just a few years, as the implanted sections of reef reproduced naturally. Additionally, the University of Hawaii is undergoing a project to selectively breed species of coral that are resistant to bleaching by using specimens that have shown to be particularly resilient. There is a long, uphill battle ahead to preserve the Great Barrier Reef, but scientific interventions provide hope that such an enormous task is possible.