Despite climate change damage, the future of coral reefs could be looking up
An experiment at the Great Barrier Reef, which involves playing recordings of healthy coral, is luring fish back to dead patches, which could lead to the reefs’ revival
Which came first, the coral or the fish? As scientists desperately search for a way to get the world’s coral reefs to rebound from the devastating effects of climate change, they might just find out.
In the Caribbean, researchers are cultivating coral “nurseries” so they can re-implant fresh coral on degraded reefs. And in Hawaii, scientists are trying to specially breed corals to be more resilient against rising ocean temperatures.
Last month, British and Australian researchers rolled out another unorthodox strategy that they say could help restoration efforts: broadcasting the sounds of healthy reefs in dying ones.
In a six-week field experiment, researchers placed underwater loudspeakers in patches of dead coral in Australia’s Great Barrier Reef and played audio recordings taken from healthy reefs. The goal was to see whether they could lure back the diverse communities of fish that are essential to counteracting reef degradation.
“Healthy coral reefs are remarkably noisy places - the crackle of snapping shrimp and the whoops and grunts of fish combine to form a dazzling biological soundscape,” said Steve Simpson, a marine biology professor at Britain’s University of Exeter and a senior author of the study. “Juvenile fish home in on these sounds when they’re looking for a place to settle.”
According to the study, the number of species present in the reef patches where healthy sounds were played increased by 50 per cent over the other patches. The new fish populations included species from all parts of the food web, such as scavengers, herbivores and predatory fish. Importantly, the fish that arrived at the patches tended to stay there.
Yes, you can buy clothes without destroying the planet. Here’s how
“Reefs become ghostly quiet when they are degraded, as the shrimps and fish disappear,” Simpson said, “but by using loudspeakers to restore this lost soundscape, we can attract young fish back again.”
The technique, if it can be replicated on larger scales, could offer scientists another tool to revive coral reefs around the world that have been ravaged by climate change, overfishing and pollution in recent years. Scientists have warned that climate change may already be accelerating too fast for some reefs to recover at all, and that conservation efforts are not keeping pace with the devastation.
Severe coral bleaching triggered by extreme heat waves killed off 50 per cent of the Great Barrier Reef, the planet’s largest coral reef, in 2016 and 2017. Such bleaching events - which occur when the nutrient-rich and colour-providing algae that live in corals are expelled because of heat stress - are occurring four times as frequently as they did in the 1980s, as The Washington Post has reported.
Five things everyone keeps on getting wrong about tropical rainforests
The researchers worked from October to December 2017 in a lagoon in the northern part of the Great Barrier Reef that has a large, shallow reef that runs along the coastline.
At the start of fish recruitment season, when fish spawn and mature, the team built 33 experimental reef patches out of dead coral on open sand about 25 metres from the naturally occurring reef. They then fixed underwater loudspeakers to the centre of the patches, angling them upward to ensure the sound was distributed in all directions evenly.
Over the course of 40 nights, the team played recordings from a healthy reef in some of the patches. In other patches, they used dummy speakers that emitted no sounds, and they left a third group of patches untouched.
The process, called “acoustic enrichment”, had a “significant positive impact on juvenile fish recruitment throughout the study period,” the researchers wrote. The acoustically-enriched reefs attracted fish faster and maintained them longer than the reefs without a healthy soundtrack, according to the study.
The researchers acknowledged that drawing fish back to dead or dying reefs will not reverse the damage by itself. But degraded reefs have a better shot at recovery if they have robust populations of fish, which play a variety of roles in keeping the coral healthy.
“Fish are crucial for coral reefs to function as healthy ecosystems,” said the study’s lead author, Tim Gordon, of the University of Exeter.
“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.”
This article was curated by Young Post. Better Life is the ultimate resource for enhancing your personal and professional life.
