Researchers lure fish to great barrier reef using underwater speakers

Scientists working to bring the Great Barrier Reef back to its former healthy state have found that young fish can be drawn to the degraded coral reef by using loudspeakers to play the sound of healthy reefs. The team calls the technique "acoustic enrichment" and think it could be a valuable tool in helping to restore the damaged coral reef. The underwater loudspeakers were placed along the reef and play healthy reef recordings in patches of dead coral.The team found that while playing the sounds, twice as many fish arrived and stayed at the reef compared to patches where no sound was played. The team says that fish are crucial to coral reef function as a healthy ecosystem.

One way to help restore the coral reef's natural recovery process is to boost fish populations. The new technique generates sounds that are lost when reefs are quietened by degradation. The team says that the healthy coral reefs are "remarkably noisy places," the crackle of snapping shrimp, whoops of grunt fish, and other sounds combine to form a biological soundscape.

The team says that juvenile fish hone in on those sounds where looking for a place to settle. When reefs are degraded, they become ghostly quiet, and shrimps and fish disappear. The young fish are attracted again using the loudspeakers. The study found that broadcasting the health reef sounds doubled the total number of fish arriving at the experimental patches of reef habitat.

The number of species present increased by 50%. The diversity includes species from all sections of the food web, including herbivores, detritivores, planktivores, and predatory piscivores. The different groups of fish at the reef provide a different function for the reef and are required for a healthy ecosystem.