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Gardening with a difference: planting corals on the reefs of Bonaire

Updated: Jun 12, 2022

The ocean is changing – rapidly, and drastically. This is no longer news, of course; however, the extent to which human activities continue to take a toll on our oceans is alarming. Not enough is being done on a large scale to reverse these effects and we might be too late to do so. That isn’t deterring the Reef Renewal Foundation Bonaire (RRFB) initiative, located on the island of Bonaire in the Dutch Caribbean, from their efforts in making a difference. https://reefrenewalbonaire.org/


Coral restoration project on Bonaire
Staghorn coral, Bonaire (these thickets can grow up to 5 feet high and 30 feet across) (photo by Courts)

Reefs support huge ecosystems that keep our oceans functioning and by association the rest of the planet; however, they are under threat and have massively deteriorated in recent years. While they constitute only 1% of the ocean floor, they are the nursery grounds for some 25% of all species of marine life. It is estimated that 33% of all fish at some stage will have lived on coral reefs. All ecosystems and their processes are interconnected. The loss of our reefs and the life that they support will have massive knock-on effects – not just for the oceans, but for us as well. If we’re serious about mitigating climate change, then the reefs need immediate attention.


RRFB’s tag line – ‘Giving Bonaire’s reef a helping hand’ – sums up their initiative perfectly. During November my daughter and I were trained by RRFB in 'coral husbandry', whereby we learnt to propagate, nuture and outplant coral cuttings from underwater coral nurseries onto the reefs. By using our experience as scuba divers, we could take part in something hands-on and proactive which proved to be hugely empowering.


The concept is simple: take advantage of corals’ ability to regenerate itself, then plant back onto the reefs. The choice of location is simple too: Bonaire’s history is rich with marine conservation efforts, with the island having been declared a protected marine reserve in the 1970s. It was also declared a demonstration site for the collaborative initiative ICRAN (International Coral Reef Action Network) to determine best practices to reverse the decline of the world’s reefs. Relative to the rest of the world’s approach to marine conservation, Bonaire has been ahead of the game for a long time.


RRFB so far has focused on restoring two coral species: elkhorn and staghorn. These species were prominent across the shallow reefs of Bonaire, but their populations were severely demolished by hurricane induced storm surges in the last 20 years. RRFB is re-establishing these populations.


Staghorn coral damaged by storm surge
Evidence of the damage that storm surge can wreak on staghorn coral (photo by Courts)
Staghorn coral restoration Bonaire
Staghorn coral outplanted via the coral restoration programme on Tori's Reef, Bonaire (photo by Courts)

With permission from the marine park authorities, the foundation took an initial batch of clippings from healthy corals on the reef some six years ago. The growth of the corals has been so successful that the project is now entirely self-sufficient, with new clippings coming from corals that RRFB have grown themselves.


The coral clippings are hung like Christmas decorations on plastic tree-like structures underwater, called nursery trees, where trained volunteers tend to them, removing algae and predators such as snails and worms. Over several months, they are left to grow until they are big enough to be transplanted out on the reef. Depending on the species, this is done either by gluing the coral to the ocean substrate with marine epoxy (and involves wielding a pick-axe to clear the rockface of algae – quite a challenge to do while suspended in the water column as a diver) or by zip-tying the fragments to bamboo structures fixed on the ocean floor.


Staghorn coral nursery Bonaire
Staghorn coral nursery trees at Buddy Dive, Bonaire

Restoration efforts are aided by coral’s unusual biology. Separate coral fragments of the same genotype can grow and merge into each other, creating a bigger coral. To ensure that the populations remain healthy and diverse, each site is a different genotype.


In the six years that the foundation has operated on Bonaire, the results are very promising. Over 25,000 coral fragments have now been outplanted on the reefs, and in 2018, the first successful spawning event (coral reproduction) of these corals was observed, which is a tremendous sign of good healthy young coral. RRFB is now including more species in their projects, such as brain coral.


Brain coral in the nursery at Buddy Dive, Bonaire
Brain coral in the nursery at Buddy Dive, Bonaire (photo by Courts)
Close up of a brain coral, Bonaire
Close up of a brain coral, Bonaire (photo by Courts)

Note that to do this type of coral husbandry qualification, one needs to be a certified scuba diver - and to have exemplary buoyancy control underwater.






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