Underwater loudspeakers could be used to revitalize devastated corals, by blasting the sounds of healthy reefs to make them more attractive to young fish. An experiment was conducted in Australia’s northern Great Barrier Reef, which has been devastated by human-led climate change in recent decades.
Healthy corals teem with masses of vibrant and diverse life, and this is reflected in the underwater sounds and other cues that they emit into the surrounding waters. Degraded corals are, by contrast, quiet places, and this could be a major problem in their ongoing fight for survival.
Corals rely on attracting a diverse population of fish to maintain a healthy ecosystem. These marine denizens care for their coral home by carrying out a range of housekeeping duties, such as cleaning and clearing away dead areas of reef, which in turn grants space for new growth.
Many fish move to a coral at a young age, and are thought to be led by sensory cues when deciding where to settle. Larval fish are less likely to be attracted to a silent coral, which is an indicator of poor health.
A new study carried out by an international team of scientists has revealed it may be possible to encourage young fish to settle on damaged reefs by playing back the sounds of healthy corals on underwater loudspeakers.
“Fish are crucial for coral reefs to function as healthy ecosystems,” says lead author Tim Gordon, of the University of Exeter, UK. “Boosting fish populations in this way could help to kick-start natural recovery processes, counteracting the damage we’re seeing on many coral reefs around the world.”
The 40-day experiment took place from October to December 2017 – a period of the year during which young fish naturally migrate to their new coral homes.
Observations made at damaged coral sites fitted with functioning speakers were compared with those made at control sites, some of which were left bare, and others of which had been rigged with dummy speakers. This was done to test whether changes in marine population and diversity resulted from the acoustic treatment itself, or the added environmental complexity that the new speaker systems presented.
According to the team, the coral sites with speakers broadcasting healthy reef sounds saw the arrival of twice as many fish compared to the control sites. Importantly, the areas benefiting from the acoustic enrichment method also exhibited 50 percent more diversity in the amount of species attracted.
The authors of the new research warn that simply encouraging fish back to damaged coral sites won’t be enough to revitalize them completely. However, the technique does show promise, and could be an effective weapon in the fight against ocean habitat loss when used in concert with other restoration methods.
A paper on the study has been published in the journal Nature Communications.
Source: University of Exeter