A group of marine experts and scientists from Australia and the UK had worked together to use underwater loudspeakers to entice fish and other marine animals to come back to live in dead coral reefs and potentially help the coral reefs to recover. They did so by replicating the sounds of healthy reefs, according to a study that was recently published in Nature Communications, the scientists used a process called acoustic enrichment.
The scientists placed loudspeakers on patches of dead coral in the Great Barrier Reef and they discovered that twice as many fish arrived, and stayed, compared to patches that they placed where no sound was played.
Saving the coral reefs
Steve Simpson, a professor of marine biology and global change at the University of Exeter said that healthy coral reefs are remarkably noisy places, the crackle of snapping shrimp and the grunts and noise of the fish combine to form a dazzling biological soundscape. Juvenile fish hone in on these sounds when they are looking for a place to settle. Reefs become quiet and still when they are disturbed and degraded, as the fish, shrimps and other marine animals disappear, but by using loudspeakers to restore this lost soundscape, we can attract young fish back again.
The lead author of the study and another marine biologist from the University of Exeter, Tim Gordon, said that the returning fish could help ecosystems recover and give those degraded patches of coral a chance of new life.
He said that fish are crucial for coral reefs to function as healthy ecosystems. Boosting fish populations in this way could help to start natural recovery processes, counteracting the damage that we are seeing on a lot of coral reefs around the world.
The 2,300 kilometer or 1,500 mile-long Great Barrier Reef has endured multiple large scale bleaching events caused by above-average water temperatures in the last 20 years, including back-to-back occurrences in 2016 and 2017. Ocean heatwaves are said to destroy the coral reefs and they are compromising its ability to recover. This then raises the risk of widespread ecological collapse.
The new research saw the amount of fish double in number because of the use of underwater loudspeakers. It also saw an increase in the number of different fish species present by 50%. This diversity could play an important part in helping the coral recover, with each species playing different roles and functions in the complicated aquatic ecosystem.
An underwater loudspeaker on a coral reef.
The real question is, could music and sound really help turn the oceanic graveyards into living underwater home again? The authors of the study are optimistic, but they suggest that there is still a long road ahead for reef recovery.
Andy Radford, a co-author, and professor in behavioral ecology at the University of Bristol said that acoustic enrichment is a promising technique for management on a local basis. However, they still need to tackle a host of other threats including climate change, water pollution, and overfishing, in order to protect these fragile ecosystems.
Radford also suggested that more research would be needed where the reefs are monitored for a longer period, to truly understand how the loudspeakers influenced the fish. He said that they tracked the experimental reefs for 40 days. While they can't necessarily tell if the same individuals remained, there was indeed an increasing number of both individuals and of species across that time, so most likely those arriving were staying.
Radford said that in that time frame, it was probably a bit soon for them to start breeding. Future work and research is needed to monitor reefs longer to know if this experiment will have a long-lasting effect.
