The Rich Sounds of Healthy Reefs May Save Them

Healthy coral reefs are remarkably noisy places, which I'm sure you have noticed if you have held your breath while hovering over one. According to Stephen Simpson, a marine biologist at the University of Exeter, in the UK, "The crackle of snapping shrimp and the whoops and grunts of fish combine to form a dazzling biological soundscape." And that very cacophony may be a lifesaver.

Along with other British and Australian researchers, he has discovered a novel way to attract diverse communities of fish back to dying coral reefs. They have been broadcasting the sounds of healthy reefs by underwater loudspeakers, and during a six-week field experiment on Australia's Great Barrier Reef, their replayed audio recordings lured back fish.

According to a study published in Nature Communications, the researchers found that twice as many fish flocked to the dead coral patches where healthy reef sounds were played compared to those where there was no sound at all. The new fish populations included species from all parts of the food chain, such as scavengers, herbivores and predatory fish, and those that arrived at the patches tended to stay there.

The technique, if it can be replicated on a larger scale, could offer another tool to revive coral reefs that have been ravaged by climate change, overfishing, and pollution. They warn, however, that climate change may already be accelerating too fast for some reefs to recover and that conservation efforts are not keeping pace with the devastation.

The loudspeaker project, called acoustic enrichment, had a "significant positive impact on juvenile fish recruitment throughout the study period," the researchers reported.

- Ben Davison