Thursday August 15, 2024
NOAA Fisheries —
In summer 2023, the Florida Reef Tract experienced the most intense heat event on record, causing widespread coral bleaching and mortality of elkhorn corals. NOAA Fisheries scientists assessed and mapped how the number and distribution of genetically distinct colonies in the population were impacted by this event.
At least 160 elkhorn coral genotypes—unique combinations of genetic makeup—were documented alive at their native reefs in this region before the heatwave. As of fall 2023, only 37 remained after the heat event—a loss of 77 percent of genotypic diversity. These were restricted to 16 reefs in the upper Florida Keys, and Miami-Dade and Broward Counties.
As of June 2023, scientists weren’t aware of any native, wild elkhorn coral that survived the 2023 heat event south of Key Largo, despite diligent survey efforts by NOAA Fisheries and partners.
While these genotypes have been lost in the wild, more than 180 genotypes are represented among elkhorn corals at coral nurseries and genebanks.