Florida Reef Tract Coral Disease Outbreak: Response



Investigations into potential pathogens and causes of the outbreak are complex and ongoing. It was first documented off Virginia Key, near Miami, in an area that is chronically stressed by a number of factors including unfavorable water quality.

Scientists monitor leading edge of disease outbreak

Identifying pathogens and monitoring sentinel coral colonies

Interventions and Treatments

Scientists and resource managers are coordinating interventions and treatments with the goal to slow or stop the spread of stony coral tissue loss disease. The most urgent needs are at the disease front in the Lower Keys. Strategies include colony-specific interventions to prevent mortality of the most important corals, efforts to reduce the pathogen load, and salvage of selected colonies to prevent the loss of the diversity and genetic structure of the corals.

Former military divers come to the aid of scientists combating coral disease

In April 2019, FORCE BLUE divers working with scientists from Nova Southeastern University are completing a 50 day dive mission to treat diseased coral colonies in the Florida Keys. Veterans with the nonprofit organization utilize their unique skills to apply antibiotic and chlorine treatments on diseased corals in the Florida Keys National Marine Sanctuary. The experimental treatments, funded by the Florida Department of Environmental Protection, aim to save priority coral colonies and provide scientific insight into stony coral tissue loss disease. As a bonus, the work also provides former combat divers with a new mission – saving Florida’s coral reefs.

Project Protect - Stony Coral Tissue Loss Disease Interdiction

A team of scientists out of Nova Southeastern University lead by Brian Walker, have been assessing and treating coral disease of the 60 largest, healthiest corals from Pompano Beach to Key Biscayne. After one year of monthly monitoring, it appears that there could be some periodicity of new disease infections. The number of required treatments s varied by month. The highest number of treatments were in June, right after the onset of the rainy season (May) and rose again in August and September, the warmest water periods. The number of new treatments has steadily dropped since early 2019. Also, the number of newly infected colonies followed a similar pattern with the highest number of newly infected large corals in May and August. There have been no newly infected large corals since November 2018, leaving 22 large monitored corals that have resisted infection to date.

before and after view of a treated coral
An identified disease lesion on a Star Coral (Orbicella faviolata) was treated in August 2018 during monthly monitoring surveys. Six months later, the treatment showed to have halted the progression of the disease. Photo: Alysha Brunelle/NSU

Probiotic Experiments

rescued corals in a tank
Shown is a diseased great star coral fragment A) untreated diseased fragment, B) untreated after 11 days, C) treated with probiotic McH1-7, and D) treated with probiotic McH1-7 after 11 days. The living tissue is a brownish color that is slowly lost over time.

While efforts continue to identify the pathogens responsible for stony coral tissue loss disease, scientists are also testing the theory that probiotics may bolster coral resistance and recovery.

Researchers with the Smithsonian, University of Florida, and University of Hawaiʻi are using healthy corals taken from Florida waters to develop probiotics that could slow or prevent disease progression. They isolate potentially beneficial microorganisms (probiotics) from more disease-resistant coral genotypes and test them on great star coral (Montastraea cavernosa), one of the species most susceptible to stony coral tissue loss disease.

Preliminary results suggest that these good bacteria on healthy corals may help defend their host from infection and that they are a plausible treatment for diseased corals. The next steps are to run more tests to try to optimize treatment and to determine if it can protect healthy corals from disease transmission. This would be essentially for protecting captive corals rescued from disease-impacted areas.

Disease intervention strategies to save Florida's largest, oldest corals

Nova Southeastern University laboratory treatment trials in tanks

Nova Southeastern University laboratory treatment trials in ocean

Direct UV treatment unsuccessful at halting disease progression


Diver Alysha Brunelle applies chlorinated epoxy to the firebreak and active disease margins on a Great Star coral (Montastraea cavernosa) as an experiment to determine if it will slow or stop progression of stony coral tissue loss disease. Credit: Brian K. Walker/Nova Southeastern University. Higher Resolution Version

Additional videos and photos

Researcher Brian Walker uses the hammer and chisel method to create a 1-2 cm wide and 1 cm deep firebreak along the scored marks around a disease margin. Credit: Alysha Brunelle/Nova Southeastern University. Higher Resolution Version

Additional videos and photos


Disease-resistant corals are being studied for restoration efforts. In laboratories throughout Florida, gene banks preserve species that could potentially be grown and transplanted along the reef.

Coral Rescue – Healthy corals of the susceptible species collected and stored in land-based facilities to maintain diversity in restoration projects.

Mote Marine Laboratory expands restoration efforts

Pillar Coral Genetic Rescue Project

Mote Marine Laboratory on Summerland Key developed a micro-fragmentation and fusion method to speed the growth of brain, boulder and star corals - crucial reef-building species known for their slow growth in the wild.

Restoration in the Age of Disease

The Florida Aquarium and conservation partners have embarked on an Florida coral reef conservation mission in the Florida Keys to introduce and ‘outplant’ more than 3,000 new genotypes of staghorn coral (Acropora cervicornis) to protect and restore coral reefs in the region from the brink of extinction. Although staghorn coral is not affected by stony coral tissue loss disease, it is a keystone coral species necessary to maintain healthy coral reef ecosystems in coastal Florida and the Caribbean.


scientist handeling coral fragments in a water tank
Mote Marine Laboratory on Summerland Key developed a micro-fragmentation and fusion method to speed the growth of crucial reef-building species. Credit: Mote Marine Laboratory