One hundred percent coral mortality at Lac Bay nursery after extreme heat
KRALENDIJK – The extreme bleaching event of 2024 has had major consequences for Acropora palmata corals in the nurseries of Reef Renewal Foundation Bonaire (RRFB). At Lac Bay, 100 percent of the corals were lost during the period studied. This is according to RRFB’s 2025 annual report.
Early in 2025, RRFB analysed the data collected during the 2024 bleaching event across its network of nurseries. In total, the health, survival and mortality of Acropora palmata were monitored at fourteen locations. Survival varied greatly by location and by genotype.
According to RRFB, Lac Bay was the location where conditions were the most extreme. Of the corals that were part of the nursery stock studied there, not a single specimen survived the event.
At the same time, the results show that not all genetic variants responded to the heat in the same way. The variants Apal01, Apal02 and Apal15 survived at almost all locations studied. Other variants, including Apal07 and Apal17, proved to be more vulnerable.
According to RRFB, these differences are important for the future approach to coral restoration. When carrying out restoration, the organisation wants to consider not only the characteristics of the coral, but also the conditions at the site where it is to be outplanted.
According to RRFB, the events of 2024 have also led to a broader search for corals that have withstood extreme heat. In 2025, surviving colonies that appear to be naturally more heat-tolerant were sought out at various places around Bonaire. These corals are being used to build a stronger stock for future restoration. At the Oil Slick Leap nursery, 47 new genetic variants were added in 2025.
RRFB writes that the heatwaves of 2023 and 2024 have profoundly changed the reefs and the restoration work. In addition to bleaching, disease also caused losses in the nurseries. The organisation therefore wants to pay more attention in the coming years to genetic diversity and to corals that have demonstrably greater resistance to thermal stress.
