Award: OCE-1801475

After centuries of human-mediated disturbances on Caribbean reefs, the appearance and composition of modern Caribbean coral reefs are vastly different from those described in the 1950s. On many reefs, stony corals have not recovered from an array of both natural and anthropogenic hazards. Many of these reefs now have an abundance of fleshy algae, but at other locations organisms such as octocorals, also known as gorgonian corals, and sponges have become the visually dominant organisms. Increases in octocoral abundance over the last few decades suggest that octocorals may represent a substitute for stony corals on present-day Caribbean reefs. However, the persistence of octocoral communities will depend on their ability to survive and recover from disturbances that have depressed stony coral abundance. The passage of Hurricanes Irma and Maria over St John, Virgin Islands in 2017 provided opportunity to assess the resilience of octocoral communities that had been studied over the preceding 4 years. The hurricanes depressed the densities of juvenile and adult octocoral colonies as much as 47%. However, there were only weak effects on octocorals measured as both the number of species present and the relative abundances of the octocoral species. Differences in the makeup of communities that existed prior to the hurricanes were still present after the hurricanes. The density of octocoral recruits (individuals that were ≤ 5 cm high) was lower in the year following the hurricanes, but returned to pre-hurricane densities in 2019. Persistently high octocoral recruitment provides a mechanism supporting ecological resilience of these communities. Octocorals provide only a subset of the ecosystem services that stony corals historically generated, but our observations illustrate how ?octocoral forests? can become the structurally dominant community on Caribbean reefs. However, that assessment does not incorporate further environmental degradation; continuing environmental degradation is a threat to all tropical marine communities. The research provides critical information on the potential futures of Caribbean coral reefs. The products of the research include a submitted technical publication, two presentations to professional meetings, and TV and radio interviews discussing the project finding. Two graduate students, 3 undergraduates, and a volunteer received professional training over the course of the study. Trainees working on the project included 4 women. Last Modified: 12/30/2019 Submitted by: Howard R Lasker