Dying coral reefs can be saved by transplanting from healthy ones: Study

This transplant method would be helpful in minimising the bleaching of coral reefs, 44% of which is already threatened according to IUCN Red List

A study conducted by the Australian Institute of Marine Sciences (AIMS) between December 2023 and March 2024 reported that coral cover has reduced on 12 of the 19 surveyed sites in Australia’s Great Barrier Reef.

Causes were reported to be extreme heat and cyclones driven by climate change. Coral bleaching is not just happening in Australia, but all over the world. An analysis of the 892 warm-water-reef-building coral species for The International Union for Conservation of Nature (IUCN) Red List revealed that 44% are threatened. 

Loss of coral reefs means loss of oceanic biodiversity, and such bleaching will continue due to global warming. But a recent study conducted in the Gulf of Eilat in the Red Sea revealed that dying corals can be saved with the help of healthy corals.

Titled ‘Ecosystem transplant from a healthy reef boosts coral health at a degraded reef’, the study’s findings show that successful transfer of organismal communities is possible between different reef families, and the potential it presents for reef restoration strategies.

Organism transfer

Benthic reef invertebrates and bacteria play crucial roles in keeping adult corals and other physiological properties of the reef healthy, as well as important for the growth, maintenance, and function of coral reef ecosystems. 

The study sought to harness this potential by utilising organismal communities from healthy reefs to influence coral health positively at degrading reefs. In a nutshell, it was a simple transplant.

For six months, biomimetically designed terracotta tiles were conditioned at both healthy and degrading coral sites, and then reciprocally transplanted. To this, the study’s authors attached some coral species for six more months. 

When a year passed, tiles from the healthy site showed richer invertebrates than the degraded site’s original tiles, found the study. More importantly, key bacteria from the healthy reef were more prevalent on its tiles as well as the tiles transplanted to the degrading site. 

Also, corals originally from the degrading site which were attached to the transplanted tiles from the healthy site displayed higher photochemical capacity, increased endosymbionts, and reduced physiological stress, measured by total antioxidant capacity and an integrated biomarker response, found the study.

Scientific intervention

Among the results the study observed were that key physiological functions of corals from the degraded site were improved after performing aCRET from the healthy to degraded reef. 

However, this method may not act on all reefs across the globe, as the ecosystem organisms may differ, and all organisms may not promote the growth of reefs. Also, such interventions require some time to show results. 

The study proposes a coral reef ecosystem transplant (aCRET) as a holistic approach to restore degraded reefs. This method can be used to boost coral health and future reef resilience, and build upon current restoration strategies, as well as a stand-alone method.

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