Reefs are supposed to be noisy – we take a look at the mission to stop their silence.
The ocean can do a lot for your mental and physical wellbeing, according to research. A Penn State University study reveals that simply hearing the ocean improves mental health. As ocean sound alone can bring health benefits to humans, evidence suggests the ocean may also heal itself through its own sound.
A healthy coral reef is alive with sound, as a variety of soniferous organisms produce vibrant soundscapes that reflect local life. Animal ecology has increasingly recognised the importance of the interconnected nature of habitats and of their acoustic fingerprints (soundscapes). Numerous fish and invertebrates develop as larvae away from reefs, at which point they use acoustic signals to detect reefs offshore when they are juveniles, replenishing local populations. Moreover, acoustic cues influence fish habitat quality, choice, and settlement. However, degradation of reef soundscapes may impair these processes.
A healthy coral reef is alive with sound.
Despite the allure and value of tropical coral reef ecosystems, they are degrading at unprecedented rates. While local factors can have significant impact on coral reefs, changes in our overall planet due to anthropogenic activities is dramatically reducing the distribution, abundance, and survival of entire coral reef ecosystems. There are many threats to coral reefs that are caused by anthropogenic activities; a warming climate, pollution, overfishing, destructive fishing practices involving dynamite and cyanide, the collection of live corals in the aquarium market, mining coral for building materials, and overfishing are just a few ways in which people damage coral reefs all around the world.
More than just providing beauty underwater, coral reefs contribute to the well-being of our planet. In hurricane-prone areas, they provide protection from the effects of the storm. Fishing stocks and tourism opportunities provided by reefs support an estimated 500 million people. Coral reefs are even considered the medicine cabinets of the 21st century with plants and animals acting as important sources for new miracle drugs that treat cancer, arthritis, human bacterial infections, Alzheimer’s disease, heart disease, viruses, and other diseases.
It has been estimated that warm-water coral reefs contain between 1 and 9 million species of plants and animals.
Despite occupying less than 0.1% of the ocean floor, tropical coral reef ecosystems provide habitat for at least 25% of known marine species, with many reef species to be discovered; it has been estimated that warm-water coral reefs contain between 1 and 9 million species of plants and animals.
With its extensive coral reef ecosystem, Australia’s Great Barrier Reef features every stage of reef development, as well as different types – from inshore fringing reefs to mid-shelf reefs, to exposed outer reefs. Continent-wide islands, coral cays and reefs are well represented as the result of geological and geomorphological evolution.
Today’s diverse seascapes and landscapes are the result of long-term climate changes, changing sea levels, and the erosional power of wind and water. With over 400 types of coral, 1,500 different fish species, and thousands of other animals, this World Heritage site reflects an ecosystem that has matured over millennia. However, cyclones, pollution, crown-of-thorns starfish outbreaks, coastal development, bleaching, and sudden large influxes of freshwater from extreme weather events have all contributed to a degradation of this magnificent reef. This has caused a significant change in soundscapes along the northern Great Barrier Reef.
By simultaneously exploring coral seeding and the beneficial partnership between corals and fish, the two projects aim to speed up the natural process of tropical reef growth and recovery.
Enter ‘Reef Song,’ a project under the Australian Coral Reef Resilience Initiative (ACRRI), which is jointly funded by The Australian Institute of Marine Science (AIMS) and BHP. The ACRRI is a two-faceted approach, investigating underwater acoustics through the Reef Song project on Ningaloo Reef in Western Australia and researching the latest coral re-seeding techniques on the Great Barrier Reef in Queensland. By simultaneously exploring coral seeding and the beneficial partnership between corals and fish, the two projects aim to speed up the natural process of tropical reef growth and recovery.
“This whole-of-ecosystem approach is exploring the best of nature – the beneficial relationship between coral and fish,” Australian Institute of Marine Science’s (AIMS) project lead Dr Mark Meekan says.
“Sound is a key part in making that magical partnership happen. We need the sounds that the fishes are listening for, to lure them in.”
Read more: Great Barrier Reef restoration technologies
To regenerate reefs, fishes must be recruited; young fishes are less attracted to post-degradation soundscapes than their pre-degradation counterparts.
AIMS acoustic scientist Dr Miles Parson explains: “Way out in the ocean fish larvae are listening for distinct and vibrant sounds of coral reefs. They’re searching for a healthy reef to settle on. Our previous research suggests fish larvae move to reefs with loud healthy coral reef sounds. But more and more reefs are struggling, which means they are losing this loud and unique reef harmonies that attract these fish.”
In the Reef Song research project, scientists are broadcasting “reef songs” underwater to attract baby fish to degraded reefs – investigating if the partnership between corals and fish can help repair coral reefs. As coral reefs struggle to recover between disturbances, this project hopes to speed the growth of corals during these critical recovery windows.
Underwater speakers will broadcast the melody of a healthy reef at selected patch reefs, so scientists can see what fish are attracted, how long they stay, and how fast each coral site grows.
Researchers are using underwater microphones, to record various healthy coral reef soundscapes – fish foraging, hunting, mating, cleaning themselves. From here, underwater speakers will broadcast the melody of a healthy reef at selected patch reefs, so scientists can see what fish are attracted, how long they stay, and how fast each coral site grows, compared to the sites without sound.
Coral reefs are incredibly complex ecosystems, full of mutually beneficial relationships that rely on one another to survive. A variety of fish species depend on corals for food and habitat, which in turn contribute to coral renewal. Several reef fish species play an important cleaning role, scraping, cleaning, and grazing areas that expose perfect surfaces for coral seedlings to settle and grow. The nutrients in fish poo also fertilises coral, helping them grow faster.
Coral reefs are incredibly complex ecosystems, full of mutually beneficial relationships that rely on one another to survive.
Scientists know the coral and fish partnership is beneficial but are specifically trying to find out is exactly how fast can fish speed coral to maturity. Additionally, scientists hope to discover what species are attracted to what sounds so they can tailor the song to attract the most beneficial fish for the reefs.
Each of the selected 60 sites will be monitored through photogrammetry techniques to track how the corals grow over time.
“The results of this project could inform reef managers with techniques that can enhance reef recovery and adaptation – not only here in Australia, but worldwide,” says Meekan.
With a rapidly growing global population, we are now seeing more than half of people are living within 100 kilometres of our coastlines. Worldwide, leaders are arguing for the sustainable use of ocean-based resources for economic growth, enhanced livelihoods, and jobs, while still preserving marine ecosystems— a process being described as the “blue economy.”
With a rapidly growing global population, we are now seeing more than half of people are living within 100 kilometres of our coastlines.
Despite an estimated 50 percent of global coral reef systems being destroyed, they contribute an estimated US$1 trillion to our global economy. Similarly, this threatened ecosystem is vital in helping achieve the United Nations Sustainable Development Goals, especially Goal 14: Life below water.
Governments could not only protect coral reefs for future generations through ‘Reef Songs,’ but generate immense economic benefits by implementing measures consistent with a “blue” economy, such as sustainable fisheries and stringent coastal development regulations. According to a report by UN Environment, International Sustainability Unit, and the International Coral Reef Initiative, the shift towards a healthy coral state by 2030 could generate US$35 billion more in tourism, commercial fishing, and coastal development in Mesoamerica, as well as US$37 billion in Indonesia.
It is vital to understand reef needs at a time when they are changing at unprecedented rates. Maybe it’s time we listen…
Melissa Márquez is a marine science education expert, currently finishing her doctoral degree at Curtin University. Born in Puerto Rico and raised in Mexico, Melissa has worked at the forefront of marine science education and communication for over a decade, hard at work combatting the misinformation that's rampant in ecological fields — and paving the way for Latina women like her in science.