Developing best practices for the restoration of massive corals and the mitigation of predation impacts: influences of physical protection, colony size, and genotype on outplant mortality

Nicolas Rivas, Dalton Hesley, Madeline Kaufman, Joseph Unsworth, Martine D’Alessandro, Diego Lirman

Research output: Contribution to journalArticlepeer-review

Abstract

Coral reefs have undergone drastic declines due to anthropogenic and natural disturbances. In response, restoration efforts were developed to recover lost ecosystem services. Restoration in the Caribbean has focused almost exclusively on branching Acropora but declines of corals with massive morphologies highlight the need to develop a multi-species approach. Recent studies have reported high mortality rates (> 50%) of outplanted fragments of massive coral taxa because of predation by fish, creating a restoration bottleneck. We conducted targeted experiments aimed at mitigating predation and understanding factors driving fish predation impacts on fragments of Orbicella faveolata. Fragment mortality due to predation was extremely high (> 80% average across all experiments). By limiting physical access to newly outplanted corals, Acropora cervicornis proved to be an effective predator deterrent, providing a predation refuge for susceptible species like O. faveolata. Protecting outplanted corals using metal spikes and cages was effective at reducing predation impacts while protection remained in place, but benefits declined immediately after barrier removal, with predation causing an average of 84% mortality one week after removal. We identified a size threshold where larger colonies (25 cm2) are less susceptible to predation than smaller corals (5 cm2). Coral genotype influenced predation impacts, with the most susceptible coral genotype experiencing 86% mortality compared to the least susceptible genotype experiencing 29% mortality after 4 weeks. The genotype most impacted by predation had significantly higher lipid and protein content, suggesting prey selectivity by fish may be driven by coral tissue characteristics. Fish impacts were driven by consumption activities and not the removal or targeting of “novel” objects within parrotfish territories as dead coral controls were not impacted while adjacent live corals experienced 100% mortality. These results suggest that outplanting genotypically diverse assemblages of large, massive morphology fragments in combination with fast growing, branching species, and utilizing physical barriers will limit predation impacts and improve the efficiency of reef restoration activities.

Original languageEnglish (US)
Pages (from-to)1227-1241
Number of pages15
JournalCoral Reefs
Volume40
Issue number4
DOIs
StatePublished - Aug 2021

Keywords

  • Coral mortality
  • Coral restoration
  • Fish predation
  • Florida reef tract
  • Orbicella faveolata
  • Palatability

ASJC Scopus subject areas

  • Aquatic Science

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