Bringing Back Reef Fish: Sustainable Impacts of Community-Based Restoration of Elkhorn Coral (Acropora palmata) in Vega Baja, Puerto Rico (2008–2023)

Abstract

In response to the severe fragmentation of Elkhorn coral, Acropora palmata (Lamarck, 1816), stands caused by a major winter swell (“Holy Swell”) in March 2008, an emergency community-based low-tech restoration was initiated in Vega Baja, Puerto Rico. Over a 15-year period, coral demographic performance and fish assemblages were monitored across four restored and four control (non-restored) 100 m2 plots. The restoration effort proved to be highly successful, leading to successful coral survival and growth, and to sustained recovery of fish assemblages, particularly herbivore guilds. Significantly increased abundance, biomass, and diversity were observed across all trophic functional groups, fishery target species, and geo-ecological functional groups in both restored and control plots. These positive outcomes were attributed to enhanced spatial complexity by long-term coral growth, “nutrient hotspots” within restored plots, the refugia effect from enhanced benthic spatial complexity, and the recovery of fish dispersal paths promoting spillover effects from restored to adjacent non-restored areas. Restoring herbivore guilds and geo-ecological functional groups played a crucial role in restoring vital ecological processes promoting reef ecosystem resilience. Recommendations include integrating fish assemblage recovery into coral restoration strategies, establishing natural coral nursery plots for future coral sourcing, and incorporating the concept of nursery seascapes for a holistic and ecosystem-based approach to restoration.