Coral Propagation and Restoration to Aid the Recovery of Populations of Acropora Corals Throughout Florida and the U.S. Virgin Islands
Florida Keys and US Virgin Islands (St. Croix and St. Thomas)
Since the 1970s, two reef-building corals, staghorn (Acropora cervicornis) and elkhorn (Acropora palmata), have experienced a significant and catastrophic decline throughout Florida and the Caribbean due to a number of causes, including disease, coral bleaching, hurricanes, and localized anthropogenic impacts. Both species were listed by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service (NMFS) as threatened under the Endangered Species Act (ESA) in 2006, after an extensive review of remaining population sizes. NMFS has proposed that they be listed as endangered species; a final determination of their status has not yet been made.
In 2009, The Nature Conservancy (TNC) received a $3.3 million, 3-year grant from the National Oceanic and Atmospheric Administration (NOAA) through the American Recovery and Reinvestment Act (ARRA) to expand on existing acroporid restoration work. NOAA has continued to fund the project through the TNC-NOAA Community-Based Habitat Restoration grant program through 2015. The project is a regional effort designed to aid the recovery of populations of Acropora corals throughout Florida and the USVI, and to provide social and economic benefits for local communities in addition to long-term ecological habitat improvements.
The short-term habitat restoration goal of the ARRA project was to enhance coral populations at 34 degraded coral reefs in 8 distinct areas of the coral reef ecosystems of Florida and the USVI by propagating Acropora corals in seafloor nurseries and then transplanting nursery-grown coral fragments to depleted reef sites. A total of 5,500 corals were outplanted to 36 sites under ARRA funding and an additional 2,000 have been outplanted so far under the new funding.
In 2000, Ken Nedimyer of SeaLife and his daughter began to propagate A. cervicornis coral fragments as part of a 4-H Youth Development project for her high school. Nedimyer later approached TNC and the Florida Keys National Marine Sanctuary about using the fragments for coral restoration purposes. In 2004, TNC and Nedimyer received funding through the NOAA-TNC Community-based Habitat Restoration Grant Program to initiate a pilot study in which corals were grown in the nursery and outplanted to Key Largo reefs after a year.
This pilot project was successful and in 2006 led to an expansion project, funded through the same source. New nurseries were built in Broward County by Nova Southeastern University, Biscayne National Park by University of Miami, and the Lower Keys by Mote Marine Laboratory. Coral fragments for this project were collected from the wild. These fragments were propagated in the nursery for a year and monitored extensively for growth and survivorship. They were then outplanted in each region across reef zones and monitored for growth and survivorship. In 2009, when ARRA monies became available, the groundwork had already been laid to significantly increase the scope of this project. The project expanded to include nurseries along the entire Florida reef tract and in St. Croix and St. Thomas, USVI.
With growth rates faster than any other Caribbean coral species and asexual fragmentation as the dominant form of reproduction, Acropora corals can be efficiently propagated using low-tech in-water nurseries. Strategically located where natural and human threats are low, in-water nurseries provide a stable setting for highly vulnerable tiny coral fragments to grow and thrive when properly maintained by local coral farmers. When coupled with advanced genetics, nursery-reared corals with high survivorship potential (typically 1 year or more in age) can be outplanted to adjacent degraded reefs to enhance the genetic diversity and population size of remnant coral populations.
To start each nursery, three fragments (10 cm or smaller) were clipped from 20 isolated wild staghorn colonies within each of the six Florida sub-regions and relocated to the established nursery in each sub-region. In addition, natural fragments that were found detached from the parent colony and unlikely to survive on their own, known as fragments of opportunity, were collected and further fragmented. In the USVI, only fragments of opportunity were collected per permit requirements. As nursery fragments grow, they are clipped to create additional fragments, all of which are marked with unique identification codes so they can be traced back to their parent colony.
Nursery sites are monitored (for presence/absence of disease, bleaching, breakage, predation, and survivorship) and maintained (algae removal as needed). The genotypic identity of all wild parent colonies from each sub-region was determined after collection. This genetic marker is a valuable tool that allows long-term tracking of recruitment and proliferation resulting from the restoration sites across Florida and the USVI. This information was added into the existing genetic library for the species to help determine genetic relationships across Florida and Caribbean sub-regions. All genotyping is conducted by Penn State University.
A total of about 6,500 individual Acropora colonies that have been raised in the nurseries have now been outplanted back to degraded reefs throughout Florida and the USVI. Corals were outplanted at sites that have conditions conducive to their survival. Different genotypes were outplanted within arrays at each site to maximize the chances of successful cross-fertilization once the corals reach spawning size (likely in 2-5 years).
How successful has it been?
Due to the success of this project, a guide has been produced for other similar projects in the region. The Caribbean Acropora Restoration Guide: Best Practices for Propagation and Population Enhancement was produced in late 2011. This guide was written by many of the partners on the project and shares lessons learned and best practices for the restoration of Acropora in the Caribbean. Some successes of the project include:
- Approximately 50,000 coral colonies are being maintained across 16 nurseries.
- Fragments being maintained in the nursery represent at least 98 different genotypes.
- This project has been taken from a small pilot study to a larger scale, high production level in about 10 years.
- Project partners are testing a variety of techniques to help improve survivorship and growth rates with the idea that more efficiency in the nurseries leads to more restoration work on reefs. This is an important next step in this work to ensure that the outplanting is completed in the most efficient and successful way possible.
Lessons learned and recommendations
This project represents a partnership between many individuals from universities, non-profits organizations, and government agencies. Working with this diverse group of partners requires open lines of communication and regular check-ins. Quarterly conference calls have helped keep everyone on the same page and allowed nursery managers the chance to communicate directly with each other. Also, nursery visits and occasional face-to-face meetings keep partners accountable and engaged.
American Recovery and Reinvestment Act
The Nature Conservancy
Coral Restoration Foundation
National Marine Sanctuary Advisory Council
Mote Marine Laboratory
University of Miami Rosenstiel School of Marine & Atmospheric Science
Nova Southeastern University
Biscayne National Park
Dry Tortugas National Park
Florida Keys National Marine Sanctuary
Southeast Florida Coral Reef Initiative
Broward County Environmental Protection and Growth Management Department
NOAA National Marine Fisheries Service
Florida Fish and Wildlife Conservation Commission
Pennsylvania State University
University of the Virgin Islands, Center for Marine Environmental Studies
Caribbean Acropora Restoration Guide, 2011 (pdf)