Coastal News

Outplanting a Boulder, More Resilient Reef

For the first time in history, 3 species of boulder coral have been outplanted back to Bonaire’s reefs: lobed star coral (Orbicella annularis), mountainous star coral (Orbicella faveolata), and great star coral (Montastraea cavernosa).

In late 2022, Reef Renewal Foundation Bonaire began outplanting boulder coral fragments that were propagated via fragmentation almost 2 years prior and reared in nurseries. All 3 species of boulder coral, 2 of which are endangered, are key building blocks of the marine ecosystem and will bolster the resilience of Bonaire’s reefs for years to come.

At their inception in 2012, RRFB initially focused on 2 species of branching coral: staghorn coral (Acropora cervicornis) and elkhorn coral (Acropora palmata). The foundation has since expanded their restoration efforts to more species, first through their larval propagation program and now fragmentation technique, as well. It is crucial to maximize the number species that benefit from restoration to ensure that future reefs are as genetically diverse and resilient as possible.

In 2019, Reef Renewal Foundation Bonaire, with a government permit and input from STINAPA, collected a few boulder coral fragments from four wild colonies around the island. These fragments were hung on specially-designed nursery trees and closely monitored for indicators of disease, bleaching, and other stressors over the following 2 years.

OLYMPUS DIGITAL CAMERA         Trays of boulder coral fragments in the nursery. (Photo credit: RRFB)

In December 2022, the first “reef-ready” boulder corals were taken to various restoration sites on Bonaire and outplanted using a novel, cement-based attachment technique. Fragments are pressed into small domes of fresh cement and secured to sand or rock; once hardened, these structures become part of the reef, where they will be monitored for the coming years by the Reef Renewal team. Although RRFB has been propagating boulder coral larvae for years, this is the first time that colonies were reared and fragmented in a nursery setting before being outplanted.

Reef Renewal Bonaire will continue to grow and propagate boulder corals in nurseries and outplant them back to the reef. The Foundation’s efforts guarantee that O. annularis, O. faveolata, and M. cavernosa, staples of Bonaire’s marine ecosystem, will continue to thrive amidst growing pressures.

“Outplanting these boulder coral fragments for the first time was a critical step for us, one that was necessary to fine-tune our restoration techniques and establish proper operating protocols. From now on, our focus is scaling up their production to make sure that, with the help of our incredible community of dedicated volunteers, thousands of corals will be outplanted back to our reefs every year”, says Francesca Virdis, Chief Operating Officer Reef Renewal Foundation Bonaire.

                               A colony of outplanted boulder coral fluoresces under blue light with a yellow barrier filter. (Photo credit: Ruth Winters)

The boulder coral project is important not only for the preservation of key species, but also for ensuring the resilience of Bonaire’s reefs in the face of growing local and global threats. By expanding the quantity and species of coral they outplant, the Foundation introduces much needed diversity to degraded reef areas, allowing them to better withstand today’s ever-changing environment and the uncertain conditions of the future.


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