Coral restoration on Bonaire

Pristine coral garden at the windward coast of Bonaire. Healthy coral reefs, like seagrass beds and kelp forest are home to diverse marine life. Warm waters, natural events and human impact threaten the health of these ecosystems. Unlike the leeward coast of the island, this side is beaten by costant strong winds and heavy underwater currents and has zero human impact.Here the reef ecosystem is still intact. Where nature makes it difficult for us to reach it,sceneries are amazingly superb.

An overhead view of Bonaire’s south coast in the Netherland Antilles, where coral reef degradation is already an ongoing process. Interely surrounded by a coral reef belt, the small Caribbean island of Bonaire, marine park since 1979, is facing a progressive coral degradation due to many different factors, naturals and anthropics. From hurricanes to excessive constructions the thin line of the natural balance is overtaken, but actions and restoring projects are already in progress.

A diver is swimming over a desertic, degraded coral reef site in the coastal waters of Bonaire. Conservation International considers the waters around Bonaire to be a hotspot of Caribbean biodiversity, anyway, in the leeward coast of the island, some sites are exposed to the dust coming from the coastal ongoing constructions and the corals are progressively suffocated by it. The particles of dust in fact are falling on the reef line and, once in the water, are falling as rain on the corals.

Marine biologist Francesca Virdis is investigating new possibilities for coral renewal using a photogrammetry software to recreate a 3D model of a restoration site for elkhorn coral. In this way she can evaluate the measures to take and make and efficent action plan.

Coral Tree in the nursery site. A coral tree, in the nursery site, holds a unique genetic strain, or genotype, of coral. The coral nursery trees are the solution adopted in order to hold fragments of coral that will grow to reach a certain dimension under the supervision of the biologists until they will be outplanted in the “restoration site” . A “full” tree can hold anywhere from 100 to 160 fragments corals.

Staghorn and elkhorn coral large nursery (on the background) at Kleine Bonaire. Reef Renewal Foundation Bonaire currently takes care of 8 nurseries with over 115 “trees” in total.

A scientist diver is doing the routine work on the fragments held on the coral tree. Every day new algae are growing on the structure and attack the coral and, if not cleaned, can also soffocate it. Both coral nursery and restoration site are monitored regularly to check survival, disease, damage, predation, tissue paling, and broken branches and more. In nurseries, this helps control and prevent issues before they occur.

Reef Renewal project scientific divers ready to go in the water for the weekly operation on the coral restoration site and nurseries on Bonaire. Renewal Reef Foundation Bonaire coordinator Francesca Virdis and her divers team, equipped with their working tools, beside the routine maintainance operation, will carry out of the water data and samples needed for the study of new outplanting techniques.

Team of divers at work on the “coral tree”. A coral tree holds a unique genetic strain, or genotype, of coral. After 4 months of assisted “propagation of the staghorn coral’s fragments in the “coral nurseries” site, scientists are harvesting and tagging the regenerated corals in order to outplant them in a specific site for the final “coral restoration”.

Marine biologist outplanting and monitoring staghorn coral new clones at the restoration site. The square bamboo’s frames used as a structural support for the coral growing is one of the methods used by the scientist to outplant the single branches nursed previously on the “coral trees” . Each new single branch is fixed onto a bamboo structure and will fuse with the one next to it. The structure will dissolve in a few years leaving only the new grown coral patch.

Project coordinator discussing an action plan with the team and volunteers. Reef Renewal Foundation Bonaire protects and restores coral reefs in Bonaire by developing new and innovative ways to restore reefs that are supported by research collaborations and shared worldwide training, engaging, and inspiring the community locally and internationally through volunteering, educational events, and outreach demonstrating that through community efforts there is still hope for coral reefs.

Trained volunteers divers supporting the project. After a specific training for the operation, the restoration project scientific team involves a large community of divers who actively participate in the maintenance of the coral trees of the nurseries. Coral restoration means moving nursery-reared corals to restoration sites. After six to eight months growing in the nursery, corals are healthy and mature enough to be transplanted to a restoration site. Each diver involved is a precious help.

Staghorn restored and healthy. Since 1980, populations of Staghorn and Elkhorn corals have collapsed throughout the Caribbean from disease outbreaks with losses compounded locally by hurricanes, increased predation, bleaching, elevated temperatures, algae overgrowth, and other factors. After 5 years from the beginning of the restoration project, the results are successful, with a few of the degraded areas almost restored and other potentially recoverable in the next future.

Staghorn coral restoration site in the caribbean sea. On the left a five years old restored patch and on the right a one year old one where is still visible the bamboo’s structure that sustain the grown coral fragments outplanted from the nursery. Once the patch is full grown the natural bamboo’s structure will dissolve. This work is a perfect example of how the human effort can be successful in sustaining a degraded ecosystem.

Scientific divers assisting at the stag horn coral spawning at night. Following the specific local prediction tables for the coral spawning (reproduction), an underwater scientific team is monitoring one of the restored coral (a 5 year old patch) site during this unique event that occurs only 2 or 3 nights during the entire year and for only 30 minutes at time. Spawning of restored corals is the last ring of the chain of the project that confirms the successfull ending of a cycle.

Scientific divers collecting coral capsules during the spawning at night. The coral capsules contains fertilized eggs and sperms. By collecting, mixing them together and rlease them in the water, the biologists are able to help the coral’s reproduction and diffusion by increasing the fecundation of a huge percentage. The assisted fecundation is an extraordinary technique to speed up the reef recovery and rebalance the loss of coral environment that occured in the last 50 years.

Lorenzo Mittiga

Coral restoration project on Bonaire