Harmony in the depths: the healing power of sound in coral reef conservation
Coral reefs are among the most critically endangered ecosystems on the planet. Warmer ocean temperatures, pollution and unsustainable fishing practices continue to cause mass destruction with severe implications for wildlife, ocean health and society. As coral bleaching events also become more prevalent, delicate reefs are dying fast.
Fortunately, scientists are exploring unlikely solutions to restore coral reefs to their former glory with the latest technique using sound. Here is an overview of how soundscapes could change conservationists’ approach to reef restoration and why saving coral reefs is crucial.
Researchers use sound in reef restoration
Researchers at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts discovered how acoustic playbacks of healthy coral reefs promote the recovery of degraded marine ecosystems.
The demise of coral reefs would lead to environmental, societal and economic collapse.
The study involved setting up speakers at three coral reefs in St. John of the U.S. Virgin Islands. The scientists then examined how many coral larvae — released from containers — migrated and settled within 30 meters (m) of the speakers. The team developed a distinct acoustic playback system ranging from 200 hertz (Hz) to 23 kilohertz (kHz).
However, this is not the first time experts have used underwater acoustic mechanisms for coral conservation. Other technologies have demonstrated the utmost precision at 20 Hz to 80 kHz, an ideal frequency for providing quality data for research purposes.
The study’s findings were astounding, with Porites astreoides larvae settling 1.7–7 times more in acoustic-rich areas compared to other sites without sound — the larvae numbers were less the further away they settled from the speakers.
The power of coral reef soundscapes
Coral reefs are actually quite noisy, producing a symphony of croaks, crackles, grunts and purrs. These sounds are mainly derived from fish and invertebrates foraging, snacking and communicating within the coral colony.
Previous studies back up recent claims suggesting larvae use these sounds to decide where to settle and grow. For instance, marine invertebrates — like corals, starfish, jellyfish, crabs and sea urchins — can detect low-frequency noises from 500 m away. However, depending on the underwater disturbances, a more accurate distance might be 10-100 m.
In many ways, soundscapes guide corals and other marine species toward adequate habitats prime for flourishing. Acoustic enrichment is also far more cost-effective and time-efficient than alternative methods, such as growing coral in laboratories and transplanting the fragments to viable sites. Because of the corals’ fragility, prior handling of corals using conventional techniques does not always work to restore colonies.
Although using sound to encourage healthier coral ecosystems is still relatively new, the WHOI study sheds light on the possibilities. Scientists must still uncover adequate frequencies and playback durations necessary for optimal results. Likewise, they must understand the long-term effects of acoustics on coral ecosystems.
Why are coral reefs important?
When looking at a healthy coral reef, one might presume they are staring at a colorful underwater garden. Yet coral polyps are actually animals, spending their days constructing expansive reef communities across shallow, tropical waters and deep seas.
Coral reefs are not just appealing to look at, though. These diverse habitats provide food and shelter to 25% of ocean fish and serve as a nursery for young aquatic animals. For instance, 7,000 species of fish, turtles, birds and plants rely on the Northwest Hawaiian Island coral reef for survival.
In addition to supporting marine biodiversity, coral reefs are essential because they:
- Act as a coastal barrier against breakwaters and strong waves.
- Provide a food source for coastal indigenous communities.
- Attract millions of tourists annually and boost local economies.
- Buffer and stabilize shorelines from erosion.
- Sequester carbon dioxide from the atmosphere.
- Produce beach sand with the breakdown of coral skeletons.
- Deliver critical medicinal ingredients to treat various conditions.
The demise of coral reefs would lead to environmental, societal and economic collapse. Therefore, efforts to conserve these fragile ecosystems are critically important.
Sound provides a glimmer of hope for coral reefs
For years, researchers have studied solutions for coral reef conservation. The WHOI’s recent exploration of sound healing is a step forward in the recovery process, paving the way for a cost-effective and ecologically safe method. Of course, it takes more than natural reef noises to fix the problem in the long term. Society must also mitigate pollution and address climate change for reef longevity.
