Survivorship and growth in staghorn coral (Acropora cervicornis) outplanting projects in the Florida Keys National Marine Sanctuary

PLoS One. 2020 May 6;15(5):e0231817. doi: 10.1371/journal.pone.0231817. eCollection 2020.

Abstract

Significant population declines in Acropora cervicornis and A. palmata began in the 1970s and now exceed over 90%. The losses were caused by a combination of coral disease and bleaching, with possible contributions from other stressors, including pollution and predation. Reproduction in the wild by fragment regeneration and sexual recruitment is inadequate to offset population declines. Starting in 2007, the Coral Restoration Foundation™ evaluated the feasibility of outplanting A. cervicornis colonies to reefs in the Florida Keys to restore populations at sites where the species was previously abundant. Reported here are the results of 20 coral outplanting projects with each project defined as a cohort of colonies outplanted at the same time and location. Photogrammetric analysis and in situ monitoring (2007 to 2015) measured survivorship, growth, and condition of 2419 colonies. Survivorship was initially high but generally decreased after two years. Survivorship among projects based on colony counts ranged from 4% to 89% for seven cohorts monitored at least five years. Weibull survival models were used to estimate survivorship beyond the duration of the projects and ranged from approximately 0% to over 35% after five years and 0% to 10% after seven years. Growth rate averaged 10 cm/year during the first two years then plateaued in subsequent years. After four years, approximately one-third of surviving colonies were ≥ 50 cm in maximum diameter. Projects used three to sixteen different genotypes and significant differences did not occur in survivorship, condition, or growth. Restoration times for three reefs were calculated based on NOAA Recovery Plan (NRP) metrics (colony abundance and size) and the findings from projects reported here. Results support NRP conclusions that reducing stressors is required before significant population growth and recovery will occur. Until then, outplanting protects against local extinction and helps to maintain genetic diversity in the wild.

Publication types

  • Research Support, American Recovery and Reinvestment Act
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptation, Physiological / physiology*
  • Animals
  • Anthozoa / cytology
  • Anthozoa / growth & development*
  • Cell Survival
  • Conservation of Natural Resources / methods*
  • Coral Reefs*
  • Endangered Species
  • Environmental Restoration and Remediation / methods*
  • Extinction, Biological
  • Florida
  • Population Growth
  • Program Evaluation

Associated data

  • Dryad/10.5061/dryad.b3f0142

Grants and funding

An award by the American Recovery and Reinvestment Act to the Coral Restoration Foundation (to CRF and KN, with financial administration by the Nature Conservancy) funded outplant work in 2012. A partnership with the Nature Conservancy supported work in 2013. NOAA’s Coral Reef Conservation Program (NA13NMF4630144: https://coralreef.noaa.gov), NOAA’s Restoration Center (www.fisheries.noaa.gov/grant/coastal-and-marine-habitat-restoration-grants), and the Coral Restoration Foundation (www.coralrestoration.org) provided additional funding for this project. A Brian Keller Memorial Fellowship at Nova Southeastern University (cnso.nova.edu/tools-resources/brian-keller-memorial-fellowship.html#loan) to MW supported his Master’s thesis. The funders had no role in study design, data collection and analysis, decisions to publish, or preparation of the manuscript.