NOAA and partners combat devastating coral disease and plan for restoration

By Gena Parsons

December 2020

As scientists and resource managers wage war on a highly lethal coral disease, rescued coral colonies in zoos and aquariums across the country are carefully being maintained, waiting for the time when they and their offspring can help restore Florida’s fragile coral reefs.

In an unprecedented response, more than 60 government agencies, academic institutions, and other organizations are methodically working to identify the pathogen responsible for the disease, create innovative treatments, conduct aggressive interventions, search for resilient corals, and undertake strategic restoration. The collaborative effort focused on Florida stands to benefit coral reefs in the Caribbean and worldwide.

three photos showing coral loss by disease
Foundational species throughout Florida’s Coral Reef continue to succumb to a disease that causes tissue loss, often resulting in death of the entire colony. This photo shows rapid progression of tissue-loss disease across a colony of symmetrical brain coral (Pseudodiploria strigosa). Photo: Brian Reckenbiel/Florida Fish and Wildlife Conservation Commission

Once vibrant and bountiful, Florida’s Coral Reef teeters on the brink of ecological collapse. For decades, North America’s only barrier reef has been in decline – threatened by a rapidly expanding South Florida population, degraded water quality, climate change, and, recently, the most devastating coral disease on record anywhere in the world.

Stony coral tissue loss disease targets half of Florida’s reef-building coral species, the ones critically necessary for providing habitat for thousands of marine species and shoreline protection for millions of people. First discovered near Miami in 2014, the outbreak spread north and south, currently sparing only the southern tip of the Florida reef tract west of Key West, in the Dry Tortugas. Beyond the continental U.S., the disease is now reported in Jamaica, St. Maarten, the US Virgin Islands, Dominican Republic, Turks and Caicos, Belize, the Yucatan peninsula and Cozumel in Mexico, St. Eustatius, Culebra in Puerto Rico, Guadeloupe, St. Lucia, and parts of The Bahamas. The disease is presumed to spread by water movement. Given the spread of the disease against prevailing current patterns, it is possible that the pathogen is being transmitted by ballast water, biofilms, and dive gear. Divers are urged to properly decontaminate their gear between dives.

Map marking Florida and Caribbean outbreaks: Caribbean - Jamaica, St. Maarten, St. Thomas & St. John (USVI), Dominican Republic, Turks and Caicos, Belize, Mexico (Yucatan/Cozumel), St. Eustatius, Puerto Rico (Culebra), Bahamas (Grand Bahama Island). See

Coral disease science is a relatively new field, and researchers are building on what they have learned from other coral diseases and disease outbreaks in other species such as chronic wasting disease in members of the deer family, white nose syndrome in bats, and the highly pathogenic avian influenza, which severely impacted the U.S. poultry population and wild bird species. Considering that effective treatments for wildlife diseases are rare, one takeaway is that the best course of action is to manage for ecosystem resilience by reducing harmful stressors, improving water quality, restoring beneficial species such as the long-spined sea urchin, and restoring fast-growing and genetically-diverse corals, while continuing to work on scaling up disease treatments.

"While corals are unique in the animal kingdom, unfortunately emerging diseases are not,” said Katie Richgels, chief of the Ecology and Epidemiology Branch at the U.S. Geological Survey’s National Wildlife Health Center. “We hope by providing some examples of other national responses, the coral reef response can start to see what it takes to manage for healthy reefs in the face of an emerging disease."

colony of knobby cactus coral
A small colony of knobby cactus coral (Mycetophyllia aliciae) removed from a Florida Keys reef will contribute to maintaining genetic diversity as scientists plan to restore the reef in the wake of the multi-year stony coral tissue loss disease outbreak. Photo: Florida Fish and Wildlife Conservation Commission

Coral rescue and restoration are a priority, with a goal of finding and propagating those corals most resistant to disease, thermal stress, and other challenges that the future will likely bring. The Coral Rescue Dashboard chronicles the results of missions in the Florida Keys to remove healthy corals from the wild before the disease can reach them. This unconventional strategy is intended to ensure that genetic diversity is preserved and that the rescued corals can serve as the parents for the next generation that will restore Florida’s Coral Reef.

Currently, nearly 2,000 coral colonies are being cared for in 13 states at 19 facilities accredited by the Association of Zoos and Aquariums (AZA). The AZA joined the coral disease response in December 2018, providing temporary homes for susceptible corals harvested from Florida Keys National Marine Sanctuary and Dry Tortugas National Park.

The Butterfly Pavilion in the Denver area wanted to help and placed 19 coral colonies on exhibit for the public to witness the special care taken to save animals not normally associated with the AZA facility or Colorado.

“Education is one of the pillars of successful conservation,” said Sara Stevens, Butterfly Pavilion aquatics manager. “Engaging inland communities taps into relatively untouched demographics that, when educated, can become resources to support coastal initiatives. While the majority of guests entering our facility had no knowledge of the disease imperiling the Florida Reef Tract, they showed a positive response to the efforts being made to help save the coral and engaged with the exhibit at a higher rate than our other aquatic displays.”

coral exhibit
The Butterfly Pavilion’s Corals in Crisis exhibit in Westminister, CO, raises awareness among an audience that is typically far removed from the ocean. Photo: Candace Carpenter/Butterfly Pavilion.

“This project brings hope for the future of the Florida reefs. Many partners are working on many different facets of this response effort, and we're honored to contribute to conservation of these species by providing them a safe home until they can be returned to a healthy reef environment,” said Jennifer Rawlings, aquarium curator at Riverbanks Zoo and Garden in Columbia, South Carolina, where 36 coral colonies are thriving.

map of continental US with red dots
Red dots show the location of facilities currently housing rescued corals from the Florida Reef Tract. Participating Association of Zoos and Aquariums long-term holding facilities include: Adventure Aquarium (New Jersey), Blank Park Zoo (Iowa), Butterfly Pavilion (Colorado), Columbus Zoo and Aquarium (Ohio), Disney’s Animal Science and Environment (Florida), The Florida Aquarium, Fort Worth Zoo (Texas), Georgia Aquarium, Jenkinson’s Aquarium (New Jersey), Maritime Aquarium at Norwalk (Connecticut), Moody Gardens (Texas), Mote Marine Laboratory and Aquarium (Florida), National Aquarium (Maryland), National Mississippi River Museum & Aquarium (Iowa), Omaha’s Henry Doorly Zoo (Nebraska), Reef Institute (Florida), Riverbanks Zoo and Aquarium (South Carolina), Sea Life Michigan Aquarium (Michigan), SeaWorld Orlando (Florida), and Texas State Aquarium.

AZA members in Virginia and Tennessee are also expected to receive corals by early 2021. Rescued corals are first quarantined and studied at Florida research facilities such as the University of Miami, Nova Southeastern University, and Keys Marine Lab before being transferred to longer term holding operations.

Scientists continue to test treatments on diseased corals in the wild and in the laboratory. While antibiotics have proven effective when applied directly to disease lesions in the form of a paste, the infection often emerges in other locations on a treated coral and it continues to spread to neighboring corals. Because mass treatment in the open ocean poses a supreme challenge, this approach has been deemed most suitable for treating the large, older survivors. Visit the Coral Disease Intervention Dashboard for the latest on treatment types and locations.

Similar to humans, corals have a microbiome – bacteria, fungi, and other microscopic organisms that together help shield them from pathogens. These beneficial microbes can protect corals by producing antibacterial compounds or toxins that kill pathogens attempting to invade. Probiotics hold promise to proactively reduce the spread by bolstering the ability of individual colonies to fight the disease. Researchers with the Smithsonian Institution and the University of Florida have identified beneficial bacteria in healthy corals taken from Florida waters that could slow or prevent disease progression. Experiments suggest that probiotic treatments may be naturally transferable from treated healthy corals to diseased corals, potentially allowing for simultaneous treatment and restoration.

“The probiotics are a promising avenue of research because they may be an effective tool for treating diseased corals as well as protecting healthy corals from infection,” explained Dr. Blake Ushijima of the Smithsonian Institution. “For any disease outbreak, effective measures are needed to manage disease transmission, treat diseased individuals, and to protect healthy populations. Therefore, if the probiotics are able to assist with two of these goals, it would greatly benefit the efforts put forth by the numerous organizations working on the [stony coral tissue loss disease] response.”

bag over corals in ocean
Probiotics injected into a weighted bag placed over an infected colony boost the coral’s ability to fight the stony coral tissue loss disease. Photo: Valerie Paul/Smithsonian Institution

Emergency action is required not only to combat stony coral tissue loss disease, but also to aggressively and strategically restore the most biologically and economically valuable areas to change the trajectory of the health of Florida’s Coral Reef and protect the economy that depends on it. NOAA leads the implementation of a first-of-its-kind approach to restore corals at seven iconic reef sites in the Florida Keys. This approach, called Mission: Iconic Reefs, involves holistically preparing and managing the restoration sites to reduce invasive species, marine debris, and other threats. This enhanced growing environment will aid in the survival of corals restored to the reefs.

Coral restoration practitioners, along with volunteers and the Florida Keys community, are eager to participate in this vitally important effort to restore, protect, and conserve the coral reef ecosystem that drives the economy and local way of life in the islands. Similar restoration strategies are being undertaken elsewhere on Florida’s Coral Reef by the National Park Service and the Florida Department of Environmental Protection.

Mission: Iconic Reefs is unlike any other restoration program undertaken worldwide, combining outplanting of multiple coral species with introduction of beneficial herbivores, removal of nuisance species, and community stewardship to help maintain the vitality of the coral,” said Dr. Andrew Bruckner, research coordinator at Florida Keys National Marine Sanctuary. “Much like the steps taken in an organic vegetable garden, this effort will restore degraded coral communities and rebuild a thriving Florida Keys reef ecosystem.”

Reef locations on Florida Keys map
Mission: Iconic Reefs focuses on seven sites in Florida Keys National Marine Sanctuary. Image: NOAA

The stony coral tissue loss disease response and the unique approach to restoration are being closely watched by resource managers in the Caribbean and around the world. Lessons learned in Florida could benefit reefs worldwide, reversing a decades-long decline and cascading negative economic impacts.

person holding coral samples
Staghorn corals grown in a land-based nursery are transported for replanting. Land-based nurseries are important tools for restoration. Photo: The Florida Aquarium

Gena Parsons is the Communications and Outreach Manager at Florida Keys National Marine Sanctuary.