With at least half of the world's corals diminished in the last three decades, efforts are underway to restore these crucial ecosystems. Steps are currently underway to rescue coral reefs, but many suggest that these programs do not go far enough to mitigate the damage caused to coral reefs. However, in December 2021, researchers revealed an encouraging signal that efforts to rejuvenate coral reefs may be proving successful.
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Home to multitudes of marine species, coral reefs are considered the most diverse ecosystems on the planet. But, due to human activities, pollution, and climate change, these living ecosystems are under severe threat.
A team of researchers led by scientists from the University of Exeter and the University of Bristol found a healthy and diverse soundscape in the ocean's depths at the site of a program designed to repair and rejuvenate destroyed coral reefs.
Among the whoops, croaks, growls, raspberries, and foghorns of aquatic creatures recorded by the team at the Coral Triangle, located in the Pacific Ocean off the coast of Indonesia, were some sounds never before documented by humanity.
These soundscapes can be used in conjunction with visual evidence to assess the health of coral reef ecosystems.
The research, published in the Journal of Applied Ecology¹, indicates that such a diverse soundscape around a reef restoration project suggests that the work is having some success.
While the soundscapes recorded at the Mars Coral Reef Restoration Project between 2018 and 2019 are not the same as those recorded at healthy reefs, the diversity of sound is at least similar.
Professor Steve Simpson said that the diversity of noise recorded by the team represents an ecosystem "coming back to life".
What is the Mars Coral Reef Restoration Project?
The reefs of South-East Asia are some of the world's most heavily threatened due to local anthropogenic stressors such as overfishing, destructive fishing practices, coastal development, and sediment and nutrient runoff associated with deforestation, agriculture, and construction².
A simple question inspired the concept behind the Mars Coral Reef Restoration Project³; is it possible to rebuild a coral reef?
Since 2011, the project has been developing and improving a cost-effective, reproducible coral reef ecosystem restoration method known as MARRS. This involves installing a web of so-called "reef stars", which are hexagonal sand-coated steel structures with coral fragments attached to them.
The reef stars are placed in barren coral rubble fields and gaps between remaining live corals. So far, more than 19,000 reef stars that incorporate 28,000 fragments of coral have been installed in the Pacific, representing one of the world's most extensive restored coral reefs.
These results seem to demonstrate that the project is having some success. But, this is not the only effort to restore coral reefs.
Mars Coral Reef Restoration Efforts Show Remarkable Progress
Video Credit: Mars, Incorporated/YouTube.com
Reversing Bleaching Events
One of the most damaging effects on coral reefs is bleaching events leading to mass coral deaths due to rising ocean temperatures, increasing pollution, and over-fishing. Bleaching damages coral by driving it to emit algae that live within its tissues, turning them pale or white.
Fortunately, bleaching does not immediately kill or destroy coral. This means that coral can recover from bleaching given enough time, generally estimated to be around a decade.
The Marine Conservation Society Seychelles (MCSS)⁴ is currently operating a project in Saint-Anne Marine National Park, located near Victoria, the capital city of Seychelles, that aims to reverse bleaching in the region's reefs. It achieves this by encouraging the growth of hard coral coverage over reefs.
The process, called coral gardening, involves collecting healthy fragments of coral and placing them on a frame anchored in a coral nursery where they can be carefully monitored.
Ultimately, the MCSS aims to create eight ocean-based coral nurseries growing 12,500 coral fragment cultures and restoring 5000 square meters of degraded coral reef. They say this could result in a 10 percent increase in live coral cover, improving fish density and diversity.
Coral gardening efforts are also underway at the Great Barrier Reef, arguably the world's most famous coral reef, in Australia. The first Great Barrier Reef nursery was first created near Cairns but was then relocated to Fitzroy Island, two years later.⁵
Climate Change: The Elephant In The Room
As admirable as coral restoration attempts are, in April of 2021, Terry Hughes, former Director of the ARC Centre of Excellence for Coral Reef Studies (2005–2020) and prominent coral reef researcher, said that he believes that current measures to save reefs are insufficient.
Biologist and climate scientist specializing in coral reefs, Ove Hoegh-Guldberg added that even if the climate goal set by the Paris Agreement of 1.5 degrees warming and zero carbon emissions by 2030 is met, the Great Barrier reef would still shrink by at least 70 percent.
These opinions were further validated in late 2021 when a comprehensive international report on the status of the world's corals⁶ revealed the catastrophic consequences of global warming on reefs.
The report, provided by the Global Coral Reef Monitoring Network (GCRMN), an operational network of the International Coral Reef Initiative, suggested that reefs can only be saved if humans move quickly to rein in greenhouse gases.
Arguably the most worrying aspect of the report was the trajectory at which corals were deteriorating. Though many reefs had bounced back from the first recorded global bleaching event in 1998, that is no longer the case.
The authors found that in the ten years between 2009 and 2019, the world lost around 14 percent of its coral reefs. The majority of this loss was down to climate change. Shortly after the report was released, world leaders convened at COP26 in Glasgow to discuss climate change.
The world leaders were reminded of the importance of reefs in terms of ecology and as critical economic entities supporting ocean-adjacent human communities across the globe.
References and Further Reading
¹ Lamont. T. C., Williams. B., Chapius. L., et al. (2021), The sound of recovery: Coral reef restoration success is detectable in the soundscape, Journal of Applied Ecology.
² Burke, L., Reytar, K., Spalding, M., & Perry, A. (2012). Reefs at risk revisited in the coral triangle,' World Resources Institute. https://www.wri.org/research/reefs-risk-revisited-coral-triangle
³ MARS, https://buildingcoral.com/
⁴ Restoring Marine Ecosystem by restoring coral reefs to meet a changing climate future https://www.mcsscoralrestoration.com/
⁵ WE REGENERATE DAMAGED CORAL REEFS BY ESTABLISHING OCEAN-BASED CORAL NURSERIES, https://reefrestorationfoundation.org/
⁶ Global Coral Reef Monitoring Network (GCRMN) is an operational network of the International Coral Reef Initiative