Do coral reef restoration projects work?


While at least half of the world’s corals have declined over the past three decades, efforts are underway to restore these crucial ecosystems. Measures are currently underway to save coral reefs, but many suggest that these programs do not go far enough to mitigate the damage to coral reefs. However, in December 2021, researchers revealed an encouraging signal that efforts to rejuvenate coral reefs may prove successful.

Image Credit: thaisign/Shutterstock.com

Home to a multitude of marine species, coral reefs are considered to be the most diverse ecosystems on the planet. But, due to human activities, pollution and climate change, these living ecosystems are under serious threat.

A team of researchers led by scientists from the University of Exeter and the University of Bristol have discovered a healthy and diverse soundscape in the depths of the ocean at the site of a program designed to repair and rejuvenate coral reefs destroyed.

Among the cries, croaks, grunts, raspberries and horns of aquatic creatures recorded by the team from the Coral Triangle, located in the Pacific Ocean off the coast of Indonesia, were sounds never documented by mankind.

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, says such a diverse soundscape around a reef restoration project suggests the work is having some success.

Although the soundscapes recorded by the Mars Coral Reef Restoration Project between 2018 and 2019 are not the same as those recorded in healthy reefs, the diversity of sounds is at least similar.

Professor Steve Simpson said the diversity of noises recorded by the team represents an ecosystem “come back to life“.

What is the Mars Coral Reef Restoration Project?

Southeast Asian reefs are among the most threatened in the world 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 of the Mars³ Coral Reef Restoration Project; is it possible to rebuild a coral reef?

Since 2011, the project has been developing and improving a cost-effective and repeatable method of coral reef ecosystem restoration known as MARRS. This involves the installation of a network of so-called “reef stars”, which are hexagonal steel structures coated in sand with fragments of coral attached to them.

Reef stars are placed in fields of barren coral rubble and spaces between remaining living corals. So far, more than 19,000 star reefs incorporating 28,000 coral fragments have been installed in the Pacific, representing one of the largest restored coral reefs in the world.

These results seem to show that the project is having some success. But that’s not the only effort to restore coral reefs.

Mars coral reef restoration efforts show remarkable progress

Video credit: Mars, Incorporated/YouTube.com

Reverse Bleaching Events

One of the most damaging effects on coral reefs is bleaching leading to mass coral death due to rising ocean temperatures, increased pollution and overfishing. Bleaching damages the coral by causing it to emit algae that live in its tissues, turning them pale or white.

Fortunately, bleaching does not immediately kill or destroy coral. This means the coral can recover from bleaching given enough time, usually estimated at around a decade.

The Marine Conservation Society Seychelles (MCSS)⁴ is currently running a project in the Sainte-Anne Marine National Park, located near Victoria, the capital of Seychelles, which aims to reverse the bleaching of the region’s reefs. It achieves this by encouraging the growth of hard coral cover on the reefs.

The process, called coral gardening, involves collecting healthy fragments of coral and placing them on an anchored frame in a coral nursery where they can be carefully monitored.

Ultimately, MCSS aims to create eight ocean-based coral nurseries, growing 12,500 cultures of coral fragments and restoring 5,000 square meters of degraded coral reef. They say this could result in a 10% increase in live coral cover, improving fish density and diversity.

Coral gardening efforts are also underway on the Great Barrier Reef, arguably the world’s most famous coral reef, in Australia. The first Great Barrier Reef nursery was first established near Cairns, but was later moved to Fitzroy Island two years later.⁵

Climate change: the elephant in the room

As admirable as coral restoration attempts are, in April 2021, Terry Hughes, former Director of the ARC Center of Excellence for Coral Reef Studies (2005-2020) and a leading coral reef researcher, said he thinks the current measures to save the reefs are insufficient.

Coral reef biologist and climatologist Ove Hoegh-Guldberg added that even if the Paris Agreement climate target of 1.5 degree warming and zero carbon emissions by 2030 is met , the Great Barrier Reef would further shrink by at least 70%. .

These opinions were further validated at the end of 2021 when a comprehensive international report on the state 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 International Coral Reef Initiativesuggested that reefs can only be saved if humans act quickly to bring greenhouse gases under control.

Perhaps the most worrying aspect of the report was the trajectory of coral deterioration. Although many reefs rebounded from the first recorded global bleaching event in 1998, this is no longer the case.

The authors found that in the ten years between 2009 and 2019, the world lost around 14% of its coral reefs. The majority of this loss was due to climate change. Shortly after the report was released, world leaders gathered at COP26 in Glasgow to discuss climate change.

World leaders were reminded of the importance of reefs in terms of ecology and as essential economic entities supporting ocean-adjacent human communities around the world.

References and further reading

¹Lamont. TC, Williams. B., Chapius. L., et al. (2021), The sound of recovery: the success of coral reef restoration is detectable in the soundscape, Journal of Applied Ecology.

² Burke, L., Reytar, K., Spalding, M., & Perry, A. (2012). Rat-risk eefs revisited in the coral triangle,’ World Resources Institute. https://www.wri.org/research/reefs-risk-revisited-coral-triangle

³ MARCH, https://buildingcoral.com/

⁴ Restore the marine ecosystem by restoring coral reefs to face a changing climate future https://www.mcsscoralrestoration.com/

⁵ WE REGENERATE DAMAGED CORAL REEFS BY CREATING OCEAN-BASED CORAL NURSERIES, https://reefrestorationfoundation.org/

Global Coral Reef Monitoring Network (GCRMN) is an operational network of the International Coral Reef Initiative

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