Stony Coral Tissue Loss Disease (SCTLD) is a hard-coral disease that causes rapid tissue loss; reportedly infecting more than 1,000 colonies of coral in the Caribbean Sea in recent years. Unlike white plague and other common coral diseases, SCTLD affects 22 species that make up 50% of hard-coral species in Florida and the Caribbean [1]. This presents a serious setback for reefs already suffering from rising sea temperatures associated with climate change, ocean acidification, pollution, fishing pressures, and other increasing human interaction [1].
SCTLD was first recorded in 2014 in Miami-Dade county, Florida by a university program funded by the federal government as part of the National Oceanic and Atmospheric Administration's (NOAA) Stony Coral Conservation and Research Program. The disease has since spread south throughout the Florida Keys and the Caribbean [5] and has been identified as a potential threat to coral reefs in parts of South America and Africa [Sources: 1, 2, 5, 8, 12, 16]. Presently, Florida's coral reef has lost 98% of its living coral cover in recent decades and is struggling to survive amid the growing pressures of disease, the impact of climate change, pollution and other serious challenges [11].
SCTLD causes a rapid loss of living tissue, with affected corals covered with white patches or exposed skeletons. This eventually leads to the loss of tissue and eventual death in the coral colony [Sources: 6, 8, 10, 13]. Healthy corals turn white when they die due to SCTLD; this color shift is not to be confused with coral bleaching: a widespread phenomenon caused by corals undergoing thermal stress. The exact causes of the disease, pathogenic or otherwise, have yet to be identified, but it is suspected that the disease is caused by bacteria and transmitted via direct contact and water circulation [5]. The prevailing perspective among scientists is that it is not just one disease agent, but rather a number of pathogens or even a single pathogen associated with environmental conditions that bring about the onset of the disease [9]. It is likely that two stressors – coral bleaching and sedimentation – degrade coral health and contributed to the emergence of this disease [12]. SCTLD can be treated by the application of a probiotic treatment. Researchers at the Smithsonian Marine Station have developed two new methods to apply these treatments to infected wild corals: a weighted bag that covers whole colonies and is injected with probiotics or a paste that is applied to the individual disease lesions [18].
The two species most affected by SCTLD in the Caribbean are Dichocoenia stokesi (elliptical star coral) and brain corals [11]. Reef building corals including Colpophyllia natans (boulder brain coral) are also affected, as are at least five endangered coral species [9] including Dendrogyra cylindrus (pillar coral), Orbicella annularis (lobed star coral), Orbicella faveolata (mountainous star coral), Orbicella franksi (boulder star coral) and Siderastrea siderea (starlet coral) [19].
To minimize its spread, officials are now recommending extreme caution for divers around infected corals and urge divers to fully decontaminate their gear between dive sites to avoid spreading the disease (Florida DEP, 2019) [14]. Crucially, they must decontaminate gear between dives as well as before and after each dive excursion, especially when traveling between countries or between infected and uninfected sites [1].
They advise divers in the Caribbean and Florida to soak their gear in a 5% chlorine bleach solution for 30 minutes and rinsing thoroughly with fresh water [8]. Divers are advised to carefully clean their gear after each dive and all swimmers on the reefs must pay extra attention not to touch any coral so as to not transmit the disease [7].
Beyond Coral has embarked on a mission to exchange information on the effects of hard coral tissue diseases on coral reefs in the Caribbean by collecting recordings and storing corals for further research purposes. Beyond Coral are studying various forms of treatment to help hard coral colonies affected by the SCTLD [Sources: 3, 4, 11].
If you would like more information about SCTLD, including ways you can help, please visit the Beyond Coral Foundation website for information on the disease and its impact on coral reefs in the Caribbean, which includes a link to a comprehensive list of information and links to the latest research on SCTLD [Sources: 0, 7].
Sources:
[0]: https://scubadiverlife.com/coral-disease-outbreak-affects-florida-caribbean/
[1]: https://www.reuters.com/article/us-environment-corals/as-new-disease-wipes-out-caribbean-coral-scientists -tear-up-reefs-to-stop-the-spread-idUSKBN1WB24D
[2]: https://www.weforum.org/agenda/2019/10/the-reef-plague
[3]: https://apple.news/A0aZiC19uReKXM3APkPBOpA
[4]: http://www.greenantilles.com/stony-coral-tissue-loss-disease-spreads-through-the-northern-caribbean/
[5]: https://www.the-scientist.com/news-opinion/as-disease-batters-florida-reefs--scientists-and-community-fight -back-65693
[6]: https://www.uff.ufl.edu/your-impact/ocean-optimist/?appeal=AA1K
[7]: https://reefresilience.org/managing-for-disturbance/managing-coral-disease/stony-coral-tissue-loss-disease/
[8]: https://nmssanctuarieseus2-dev.azurewebsites.net/news/aug18/coral-disease-mystery-florida-keys.html
[9]: http://www.alertdiver.com/stony-coral-tissue-loss-disease
[10]: https://www.naturetoday.com/intl/en/nature-reports/message/?msg=25028
[11]: https://ambergriscaye.com/forum/ubbthreads.php/topics/536122/detecting-stony-coral-tissue-loss-disease.h tml
[12]: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241871
[13]: https://naturefoundationsxm.org/2019/10/23/nature-foundation-re-surveys-the-impact-of-coral-tissue-loss-di sease-on-st-maarten-reefs-coral-colonies-still-strongly-impacted-by-the-disease/
[14]: https://www.frontiersin.org/articles/10.3389/fmars.2019.00678/full
[15]: https://abcnews.go.com/US/huge-disaster-race-save-coral-caribbean/story?id=65886149
[16]: https://www.frontiersin.org/articles/10.3389/fmars.2020.00163/full
[17]: https://www.wmnf.org/floridas-devastating-coral-disease-spread-caribbean-scientist/
[18]: https://floridakeys.noaa.gov/coral-disease/
[19]: https://nmsfloridakeys.blob.core.windows.net/floridakeys-prod/media/docs/20181002-stony-coral-tissue-los s-disease-case-definition.pdf