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What is Stony Coral Tissue Loss Disease?

Beginning in fall 2014, an outbreak of the previously undescribed stony coral tissue loss disease was identified near Virginia Key, Miami. It  spread north and south to impact nearly all of Florida’s Coral Reef and it remains active to this day. By 2017 the disease had spread to the northern extent of the reefs in Martin County, and by late spring 2021 had reached Dry Tortugas National Park. While past outbreaks of other diseases have subsided during the cooler winter months, this disease has continued with no indication of seasonality and without any interruption from Hurricane Irma or other storm events. 

Nearly half of Florida’s 50 stony coral species are impacted by this disease, including some major reef-building corals like the boulder brain coral. Different coral species are affected in different ways to this disease – some species experience 100% mortality, while others have a lower mortality rate or  lose some coral tissue without completely succumbing to the disease. Millions of corals have likely died on Florida's Coral Reef as a direct result of this disease. 

Scientists are studying coral tissue and environmental samples to identify potential causes behind the disease. Unfortunately, the cause has not yet been identified, although recent research has indicated that bacteria is involved with the infection. Antibiotics have been effective in combating disease progression on infected coralsHowever, scientists still don’t know if  bacteria are the main cause of the disease or secondary and taking advantage of an already weakened coral. Additionally, rather than having a single culprit behind the disease, multiple factors or pathogens can contribute to coral disease, making the definitive causes of any coral disease outbreak hard to determine. Do you have specific questions you want answered about the disease? Please see our FAQ! 

The Florida Fish and Wildlife Conservation Commission is working with dozens of partners from federal, state, and local agencies, non-governmental organizations, universities, and members of the community to investigate the disease and save Florida’s corals. Please explore this website to learn more about SCTLD and the scientific community’s response to it.

 Stony coral tissue loss disease is an unprecedented coral disease outbreak due to its:

grecian coral with disease
  • Large geographic range - Nearly 90% of Florida’s Coral Reef has been affected – over 109,700 acres. 
  • Long duration - This disease was first observed in 2014 and has spread across Florida’s Coral Reef for more than six years. 
  • Number of coral species affected - Over 20 of the approximately 50 species of Florida’s stony corals are susceptible to stony coral tissue loss disease. 
  • High prevalence - For the most susceptible species to the disease, prevalence can be as high 66% to 100% of all colonies surveyed. 
  • High lethality - Once a coral begins to lose living tissue, the colony will likely die within weeks to months depending on the species.