Activities such as grinding fish teeth and snapping shrimp claws contribute to the din surrounding a coral reef, which can often be heard from distances up to a few kilometers away. To test whether the racket affected young fish, Stephen Simpson of the University of Edinburgh and his colleagues constructed 24 patches of artificial reef. The researchers outfitted half of them with speakers and broadcast recordings of reef noise, whereas the other half were kept silent. Of the two main types of fish attracted to the fake reefs, both cardinalfish and damselfish exhibited a preference for the louder reefs compared to the quiet ones. The two species did show differences in what types of noise they favored: damselfish were drawn more to higher-frequency sound, but cardinalfish exhibited no such preference.
The discovery that fish respond to reef sounds suggests a potentially valuable management tool, the authors say. "This is a significant step forward in our understanding of their behavior, which should help us to better predict how we should conserve or harvest populations of reef fishes in the future," Simpson remarks. "It should also alert policymakers to the damage that human activities like drilling and shipping may have on fish stocks because they drown out the natural clues given by animals."