By RRFB Intern Jette Damminger
Lac Bay is a shallow and dynamic ecosystem on Bonaire’s southeast coast where coral reefs, seagrass beds, and mangroves meet – making it both ecologically rich and highly sensitive to change. This year, Reef Renewal Foundation Bonaire (RRFB) has expanded its nursery here to include a wider range of stony coral species that are more vulnerable to heat stress. By studying and cultivating these corals under Lac Bay’s challenging conditions, we’re gaining valuable insight into resilience that can guide restoration across the island’s reefs.
Our Lac Bay restoration efforts are supported by WWF Dutch Caribbean and began as part of STINAPA Bonaire’s Lac Pa Semper initiative.
Background
Coral reefs are critical to Bonaire’s way of life: they support tourism, sustain fisheries, protect coastlines, and hold deep cultural value (Zanten and Beukering, 2012; van der Lely et al., 2013). However, 2023 and 2024 brought unprecedented sea surface temperature spikes that triggered widespread bleaching across the island’s reefs (Eckrich et al., 2024).
While most of RRFB’s restoration efforts are focused on Bonaire’s west coast and around Klein Bonaire, we’ve expanded coral restoration efforts to include Lac Bay in recent years. This popular area for windsurfing, kayaking, and snorkeling is surrounded by interconnected ecosystems of seagrass beds, mangroves, and coral reefs. During 2023 and 2024’s record-breaking heatwaves, this shallow bay has experienced extreme temperatures, making its reef ecosystems especially vulnerable. With its unique conditions, Lac Bay serves as an invaluable natural laboratory—an environment where coral species and genotypes can be studied for their resilience under extreme stress.
Now in the fourth year of a five-year project at Lac Bay, RRFB is working to boost coral abundance through fragmentation while safeguarding genetic diversity among coral genotypes. The insights gained here not only guide restoration within the bay but also strengthen efforts across Bonaire’s reefs.
Responding to Bleaching
RRFB’s restoration efforts in Lac began with a focus on two key, reef-building branching coral species, staghorn (Acropora cervicornis) and elkhorn coral (Acropora palmata), both of which are critically endangered. Following the severe bleaching event of late 2024, which caused a sharp decline in branching coral populations (De Kool et al., 2025), an extension of the project allowed us to expand our focus on boulder and brain corals.
By working with more sensitive stony coral species, we can preserve genetic diversity across a variety of reef-building populations while developing restoration approaches that are more resilient to shifting environmental conditions. With Bonaire’s reefs still reeling from two consecutive mass bleaching events and potentially more in the future, the need to strengthen reef resilience has never been more urgent. Diversifying the coral genotypes we propagate and identifying those with higher heat tolerance is a key step in ensuring Lac Bay’s reefs can endure a warmer future.
From Trial to Success: Developing Effective Nurseries
Beyond increasing coral abundance and genetic diversity, this project also focuses on testing nursery designs suited to Lac Bay’s unique environment, where little data exists to guide restoration. Our first approach was a vertical branching nursery, placed in deeper waters of the bay at a depth of 2.5 m. While branching nurseries have proven successful at other RRFB nursery sites, in Lac Bay it faced challenges such as high turbidity, excessive algal growth, and difficult logistics of reaching the site from shore. In response, we developed a horizontal rope nursery in the shallow backreef of Sorobon in 2024 near former stands of staghorn and elkhorn coral. This sheltered location offers easier access, better conditions for coral growth, and greater efficiency in day-to-day maintenance.
Comparing both nursery designs has been a valuable learning process, allowing us to establish and refine an effective protocol for coral fragmentation in Lac Bay’s distinctive environment. Maintaining the horizontal rope nursery involves scouting across the bay for healthy coral colonies, fragmenting and transplanting them into the nursery, and carrying out regular maintenance- tasks that require careful logistics and consistent team effort. Following record heatwaves in 2023 and 2024, we’ve ramped up our scouting efforts, especially during the onset of peak bleaching season. Locating and propagating colonies that survived extreme heat stress is especially important, as these corals likely carry traits that make them more resilient to rising sea surface temperatures and other stressors. By identifying, fragmenting, and expanding these heat-tolerant genotypes, we not only enhance overall diversity but also give Lac Bay’s reefs a stronger foundation to withstand the future impacts of climate change.
How it Works:
Coral fragging gives corals a “cutting-edge” boost. With coral fragging, a single colony can grow into many, helping restore reefs faster and strengthen their resilience.
Dual Location Approach
At present, our Lac Bay nursery hosts 21 genotypes across eight coral species. In our most recent efforts, fragments from each genotype are split evenly: half are transplanted back into the Lac Bay nursery, while the other half are relocated to our well-established nursery site at Oil Slick on the west coast of Bonaire. This dual approach allows us to create replicate populations in different environments, enabling comparisons of how specific genotypes perform under varying stressors such as elevated sea surface temperatures and intense light. Moreover, maintaining Lac Bay genotypes at Oil Slick serves as a safeguard—an “insurance population”—should another severe bleaching event occur in the Dutch Caribbean. Since Lac Bay typically experiences higher temperatures than Bonaire’s west coast, this strategy helps ensure the survival of valuable coral genotypes even under extreme conditions.
Project Supporters and Collaborators
This project is currently supported by WWF Dutch Caribbean. It began as part of the larger “Lac Pa Semper” project led by STINAPA Bonaire. All restoration activities align with the Bonaire National Marine Park Management Plan 2022-2028, published by STINAPA Bonaire.
References
1. van Zanten, B. T. & van Beukering, P. J. H. Coastal protection services of coral reefs in Bonaire. (Institute for Environmental Studies, VU University Amsterdam, 2012).
2. van der Lely, J. A. C. et al. The total economic value of nature on Bonaire. (Institute for Environmental Studies, VU University Amsterdam, 2013).
3. Eckrich, C., Francisca, R. L., de Kool, D. M., Rempel, H. S. & Grol, M. G. G. Coral bleaching in the Bonaire National Marine Park from 2016–2023. (Dutch Caribbean Biodiversity Database, 2024).
