Study reveals fish soundscapes across restored coral reefs

fish soundscapes, restored coral reefs

On reef restoration projects in Indonesia seeking to revive marine ecosystems, scientists found ‘fish songs’ being resonated, indicating the ecosystems were coming back to life

Previously destroyed reefs across thousands of square metres in Indonesia are under renovation, according to a study published in the Journal of Applied Ecology.

Of these, scientists found a heathy, diverse soundscape on the restored reefs – indicating a renewed, lively ecosystem.

Marine life is dependent on these ecosystems, and coral reefs are biomes which have been put under immense pressure by climate change, human activity, coral bleaching and other factors. Consequently, fish populations and biodiversity have increasingly been affected with coral reef and habitat destruction.

It was previously unclear whether these new corals would revive the entire reef ecosystem, but these sounds – many of which have never been recorded before – were used alongside visual observations to monitor the ecosystems.

Among the sounds along the coral reef restoration project were “whoops, croaks, growls, raspberries and foghorns”.

Although soundscapes of the restored reefs are not identical to those of existing healthy reefs, the diversity of sounds is similar, which implies a progressively healthier and better functioning ecosystem, as there were significantly more fish sounds recorded on both healthy and restored reefs than on the degraded ones.

Increasing diversity of returning fish

Acoustic recordings taken in 2018 and 2019 were used as part of the monitoring programme for the Mars Coral Reef Restoration Project, and this study.

Additionally, hexagonal metal frames called ‘Reef Stars’ are seeded with coral and laid over a large area, these stars stabilise loose rubble and kickstart rapid coral growth, which helps lead to the revival of the broader ecosystem.

Lead author Dr Tim Lamont, of the University of Exeter and the Mars Coral Reef Restoration Project – which is restoring the reefs in central Indonesia – said: “Restoration projects can be successful at growing coral, but that’s only part of the ecosystem. This study provides exciting evidence that restoration really works for the other reef creatures too – by listening to the reefs, we’ve documented the return of a diverse range of animals.”

Professor Steve Simpson, from the University of Bristol, added: “Some of the sounds we recorded are really bizarre, and new to us as scientists. We have a lot still to learn about what they all mean and the animals that are making them. But for now, it’s amazing to be able to hear the ecosystem come back to life.”

“Our work is helping the reefs come back to life”

Mochyudho Prasetya, of the Mars Coral Reef Restoration Project, said: “We have been restoring and monitoring these reefs here in Indonesia for many years. Now it is amazing to see more and more evidence that our work is helping the reefs come back to life.”

Professor David Smith, Chief Marine Scientist for Mars Incorporated, added: “When the soundscape comes back like this, the reef has a better chance of becoming self-sustaining because those sounds attract more animals that maintain and diversify reef populations.”

When asked about the numerous threats facing coral reefs, such as climate change and water pollution, Dr Lamont stated: “If we don’t address these wider problems, conditions for reefs will get more and more hostile, and eventually restoration will become impossible.

“Our study shows that reef restoration can really work, but it’s only part of a solution that must also include rapid action on climate change and other threats to reefs worldwide.”

The study was partly funded by the Natural Environment Research Council and the Swiss National Science Foundation and was led by researchers from the University of Exeter and the University of Bristol.


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