Coral reef restoration by the tourism sector: |12 June 2023

A diver cements a nursery-grown coral using a pastry bag (Photo credit - N. Thake)

Nature Seychelles pioneers science-based method of measuring success

Coral reef restoration projects are becoming a popular corporate environmental responsibility activity at hotel resorts. Such involvement of private businesses offers the opportunity to expand coral reef conservation. Unfortunately, these projects are oftentimes PR-heavy but scientifically light. The main problem is that the hotel staff don’t monitor the restored reef over time to quantify the success or failure of the restoration activity. There is a lack of user-friendly monitoring methods for hotel staff that are robust enough to detect changes over time.

To solve this monitoring problem, the team at Nature Seychelles restored a patch reef at Petite Anse Kerlan, at the Constance Lemuria 5-star resort on Praslin. Before the mass coral mortality from the 1998 El Niño – Indian Ocean Dipole, the exposed sandy bay of Petite Anse Kerlan contained a diverse shallow-water coral reef. Since the 1998 coral bleaching event, the patch reef was unable to recover on its own.

The Nature Seychelles team have now published the new low-tech method it developed for monitoring the survival and growth of coral transplants. The method is easy to implement by staff, without scientific training, using the standard resources available at a hotel resort.

The term “boutique restoration” was coined by Nature Seychelles for a restoration tailored to a hotel resort's needs while complying with the science-based principles of ecological restoration. Here the restored patch reef had to be accessible to hotel guests by snorkelling (1 to 3m depth), and within 50m of the beach, which is the length of an Olympic-sized swimming pool.

The branching/tabular, massive, and encrusting corals transplanted at Petite Anse Kerlan were raised by the Nature Seychelles Reef Rescuers team in midwater ocean nurseries within the Cousin Island Special Reserve. The coral fragments raised in the nurseries were survivors of the 1998 mass bleaching event, found at two nearby patch reef donor sites. The nursery corals were attached to the sea bottom at the restoration site using a special cement mix developed by Nature Seychelles.

The corals transplanted were photographed with a reflective square tile in the field of view. An underwater map of the site allowed navigation and resighting of the monitored colonies. To monitor survival and growth over time, divers used the map and the reflective tiles, to find the corals and record status (alive, dead, bleaching), and took a photograph. Then, the coral size shown in the digital images was measured using open-source software. The low-tech monitoring method was good enough to detect the expected survival of coral transplants, with encrusting and massive corals outperforming branching corals at this shallow site.

“Nature Seychelles has a long history of collaborating with the private sector for ecosystems and

species restoration. We have helped island management and owners on Cousine, Fregate, Darros, Denis islands among others to restore their islands. Importantly all these projects have been underpinned by sound science, the methods made available as manuals and toolkits and the results published in peer-reviewed journals,” says Dr Nirmal Shah, chief executive of Nature Seychelles.

“Our new science-based user-friendly method is a game changer. It gives hotel resorts the monitoring tools they were missing, so they can now get involved as full partners in coral reef restoration worldwide,” says Dr Sarah Frias-Torres, lead author of the publication.

The work was funded through grants to Nature Seychelles by the United States Agency

for International Development (USAID), and the Global Environmental Fund (GEF)/ United Nations Development Program (UNDP)/Government of Seychelles Mainstreaming Biodiversity Project.

Publication details:

Frias-Torres S, Reveret C, Henri K, Shah N, Montoya Maya PH (2023) A low-tech method for monitoring survival and growth of coral transplants at a boutique restoration site.

https://peerj.com/articles/15062/

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