Science & Research

A Pillar Coral (Dendrogyra cylindricus), which is a threatened species showing advanced tissue loss due to SCTLD. A prime example of tissue loss in corals. Credit: Leslie Henderson, NOAA

Leslie Henderson, NOAA

Stony Coral Tissue Loss Disease

Background

Stony Coral Tissue Loss Disease (SCTLD) is a lethal bacterial pathogen that affects over half of the coral species in the U.S. Virgin Islands (more than 20 species).^[1] SCTLD moves quickly, killing healthy coral tissue and leaving behind a stark white skeleton. Unlike coral bleaching in which corals may recover to a healthy state, recovery from SCTLD is not likely. Upwards of 60% decline of live coral cover on reefs has been documented in some areas.^[2]

“Continued research, management, collaboration, and outreach won't be the cure for the disease, but they minimize its impact. As coral diseases become more prevalent and virulent, the park can use past disease outbreak responses to inform future ones. Successful responses to outbreaks in the past share the common denominator of collaboration.”

- Kristen Ewen, Biological Science Technician, Christiansted National Historic Site (CHRI) National Park Service

 

Disease progression on a Boulder Brain coral at Black Point, St. Thomas, USVI. Credit: Sonora Meiling, University of the Virgin Islands

Sonora Meiling, University of the Virgin Islands

SCTLD is transmissible through water circulation and direct contact with already diseased corals. However, many aspects of this disease are still unknown. While coral disease can be common, SCTLD elicits particular concern to the U.S. Virgin Islands and mainland United States research due to its high mortality rate, widespread range, and rapid transmission rate.^[3] Although SCTLD does not pose a direct threat to human life, as coral reefs die, island communities become more susceptible to strong storm surges, loss of biodiversity, and food insecurity.First documented in Florida in 2014, the disease spread to Saint Thomas in 2019, and is now confirmed on St. Croix.^[4] Initial sightings were reported at the Underwater Trail at Buck Island Reef National Monument in June 2021, and efforts to preserve the park’s coral have been in place ever since.

 

Volunteer NPS Blue Card diver Rico Diaz treating a highly susceptible brain coral in the underwater trail at BUIS. He is using a method of applying amoxicillin paste from a syringe to distribute the treatment onto the coral.

NPS photo (Kristen Ewen)

What the National Parks Service is Doing

National Park Service scientists are actively performing intervention techniques to thwart the spread of SCTLD within the park. The primary focus of our efforts center around preventing diseased coral colonies from dying. The most successful intervention so far is the application of an antibiotic paste along lesion edges. The paste is a mixture of veterinary-grade amoxicillin and Coral Cure Base2B paste (designed and created by Ocean Alchemists LLC). Antibiotic intervention halts the progression of the disease lesion and boasts up to a 90% effectiveness rate on some coral species.^[5] Additionally, National Park scientists have tagged 40 corals around the Underwater Trail and specifically track these tagged coral colonies to determine effectiveness of the antibiotic treatment.

NPS has partnered with more than a dozen Virgin Islands Territory organizations in a collaborative effort to halt the progression of SCTLD. Learn more about the collaborations at Virgin Islands Coral Disease - VI-CDAC (vicoraldisease.org).

 

Rico Diaz swims past a heavily diseased brain coral to try to find a more suitable candidate for treatment. Treatment methods focus on large corals with small lesions to optimize treatment effort and distribution.

NPS photo (Kristen Ewen)

How Can You Help?

Volunteer!

NPS is actively seeking volunteers to participate in coral treatments. If you are a strong snorkeler, love to learn, and can commit at least one volunteer day a month, NPS would love your help in weekly coral treatments. e-mail us for more information.If you want to scuba dive and help treat diseased corals contact the St. Croix Strike Team at: [e-mail]

Report what you see!

Our tagged corals at the Underwater Trail have information cards next to diseased corals indicating how to report those colonies. Take a picture of our tagged corals with an underwater camera and send us the photos! That information is invaluable as it helps us to look at the health of coral colonies more frequently.As you enjoy the beautiful coral reefs at Buck Island National Reef Monument and notice large white patches of exposed coral skeletons (especially on brain and pillar corals), take a picture and e-mail us. Location of the photo taken is always helpful. The park will be able to dispatch scientists to go out and apply treatment.Spread the word!

Practice reef etiquette!

Never stand, rest, or touch corals, maintain proper buoyancy when diving or snorkeling, never anchor in areas where coral is present, and wear reef-safe mineral sunscreen (avoid oxybenzone, avobenzone, or octinoxate; instead look for ingredients like zinc oxide or titanium dioxide).Every coral is valuable, do your part to preserve our oceans.

Literature Cited

Stony Coral Tissue Loss Disease. Reef Resilience Available at: https://reefresilience.org/managing-for-disturbance/managing-coral-disease/stony-coral-tissue-loss-disease/. (Accessed: 29th October 2021)

NOAA and partners combat devastating coral disease and plan for restoration. Office of National Marine Sanctuaries Available at: https://sanctuaries.noaa.gov/news/dec20/stony-coral-tissue-loss-disease.html. (Accessed: 29th October 2021)

Intervention strategies. VI-CDAC Available at: https://www.vicoraldisease.org. (Accessed: 29th October 2021)

Shilling, E.N., Combs, I.R. & Voss, J.D. Assessing the effectiveness of two intervention methods for stony coral tissue loss disease on Montastraea cavernosa. Sci Rep 11, 8566 (2021). https://doi.org/10.1038/s41598-021-86926-4

^[1] Stony Coral Tissue Loss Disease. Reef Resilience Available at: https://reefresilience.org/managing-for-disturbance/managing-coral-disease/stony-coral-tissue-loss-disease/. (Accessed: 29th October 2021)
^[2] NOAA and partners combat devastating coral disease and plan for restoration. Office of National Marine Sanctuaries Available at: https://sanctuaries.noaa.gov/news/dec20/stony-coral-tissue-loss-disease.html. (Accessed: 29th October 2021)
^[3]Stony Coral Tissue Loss Disease. Reef Resilience
^[4] Intervention strategies. VI-CDAC Available at: https://www.vicoraldisease.org. (Accessed: 29th October 2021)
^[5] Shilling, E.N., Combs, I.R. & Voss, J.D. Assessing the effectiveness of two intervention methods for stony coral tissue loss disease on Montastraea cavernosa. Sci Rep 11, 8566 (2021). https://doi.org/10.1038/s41598-021-86926-4