by Joan Conover and Christina Carter
Our marine environment is changing. Sea surface temperatures are increasing and sea levels are rising. Water quality is degraded by silt and pollution. Oxygen levels and acidification are fluctuating. In the face of these impacts, stresses on marine life become obvious: some species are weakened and more diseases become established.
It’s no surprise that some corals are now susceptible to a new disease. Caribbean corals are currently facing a pandemic of their own. First identified in Florida in 2014, Stony Coral Tissue Loss Disease (SCTLD) now affects more than 30 species of corals in the Caribbean. It spreads rapidly and has a high mortality rate. Let’s learn what the disease looks like, how to help prevent its spread and — should you encounter affected corals — how to report your sightings to help with tracking and research efforts.
Stony coral tissue loss disease is different from the coral bleaching we are familiar with. Let’s re-cap about coral bleaching. It is the result of the environmental changes directly related to heating.
Coral is a combination of plant and animal living in a symbiotic partnership. It is comprised of tiny polyps that build shells around their bodies and microscopic algae called zooxanthellae, which live in the tissues of the polyps. The zooxanthellae provide the coral coloration.
Environmental changes such as increased temperature, increased sedimentation, and pollution, plus increased exposure to sunlight, are major factors. All of these, when added to the decrease in oxygen levels of the waters, stress the coral. It is the coral stress response that then expels the zooxanthellae. This stress response has been recognized for the past hundred years, but has accelerated in recent decades.
When the symbiotic relationship between the polyps and the zooxanthellae is disturbed, photosynthesis fails, and the coral does not receive food and energy — it starves. When the zooxanthellae are expelled, the coral becomes translucent or transparent. There is still tissue on the coral skeleton but you can see through the coral polyps to the skeleton, which is white, leading to the term “coral bleaching.”
This transparency of the coral tissue is a hallmark of coral bleaching and it’s a key factor in distinguishing bleaching from the new coral disease. When coral bleaches, since the tissue is still present, there is potential for recovery should water temperatures cool enough in time for the coral polyps to re-absorb their zooxanthellae.
Stony Coral Tissue Loss Disease
SCTLD is different from coral bleaching — it is an infectious disease. This disease primarily affects pillar, brain, star, and starlet corals. It
kills them with a hallmark signature of the complete loss of living tissue, which sloughs off the diseased coral leaving a bare skeleton. The disease can be confused with bleaching, and it can look like other coral diseases or even fish bites.
Resources to assist in disease identification include:
• The ID poster at Stony Coral Tissue Loss Disease Gulf and Caribbean Fisheries Institute (https://bit.ly/3HZNcni). This poster seeks to help
Caribbean marine natural resource managers monitor, identify and mitigate against SCTLD.
• AGRRA — good for serious coral observers — at https://bit.ly/340XNPy.
• The downloadable image cards at https://bit.ly/3FYk9OZ
Caribbean locations of SCTLD
Areas with confirmed SCTLD infection currently include Florida, Jamaica, Mexico, St. Maarten, the US Virgin Islands, the Dominican Republic, the Turks & Caicos Islands, St. Martin, Belize, Statia, The Bahamas, Puerto Rico, the British Virgin Islands, Guadeloupe, the Cayman Islands, St. Lucia, Honduras, Martinique, St. Barths, and Dominica.
A video created last year with commentary by diver James Fatherree documents the speed with which SCTLD can spread: “In September of 2020, it was discovered in the waters around Roatan for the first time, and I saw hundreds of affected corals while there in June of 2021. That, of course, means there are thousands of corals around the island that are dying or already dead.”
Coral disease research & resources
Researchers and managers across the Caribbean are tracking the spread of SCTLD, developing treatments and monitoring their effectiveness, working on disease prevention and on ways to save the genetic diversity of stony corals. They hope to identify the cause of the disease and find additional ways to alleviate this disaster. Some sources of credible information and links to contribute to Caribbean efforts include the following:
• US National Oceanic & Atmospheric Administration NOAA Coral Reef Conservation Program
NOAA has been a leader in providing citizens with information on SCTLD and disseminating best practices. It recognizes different ways reef systems can be inadvertently contaminated by watersports activities, including diving.
• Florida Keys National Marine Sanctuary has an excellent website focused on the work being done in Florida on coral disease: https://bit.ly/3oN8oF9. Its primary focus is to provide detailed guidance to help prevent spread of coral disease; this includes a disinfection process recommended for dive gear, and more. While focused on Florida reefs, much of the coral information and the Diver Guidelines are suitable for all areas of the Caribbean. The Florida Keys web pages include coral tagging information, observation/ reporting, and excellent downloadable coral disease identification cards (https://bit.ly/3uTEIdw) — a must for all citizens, cruisers and divers.
• Florida Department of Environmental Protection The Florida Department of Environmental Protection, partnering with NOAA, supports major coral disease efforts (https://bit.ly/3fTNG1O). You can also find more information and ways to help through the Florida Fish and Wildlife Commission at https://myfwc.com/research/habitat/coral/disease.
• Gulf and Caribbean Fisheries Institute (GCFI)
A key collaborator with governmental and educational organizations, the Gulf and Caribbean Fisheries Institute (www.gcfi.org.) supports the exchange and dissemination of information on marine and estuary science and resources among various organizations, and facilitates communications between government agencies.
With its focus on lionfish infestation, sargassum influx, and SCTLD, GCFI is available to inform with publications, conferences, videos and webinars. In coordination with Cartagena Convention Secretariat, United Nations Environment CEP, GCFI has published, as of September, 2021, a major coral disease document called the White Paper (https://bit.ly/3KAhjmO), providing status of projects from research efforts to case studies, coral rescue/propagation efforts and more. Most of the newest treatment research, coral propagation/ relocation efforts, identification of preventative measures, and other topics of interest are included.
• Atlantic Gulf Rapid Reef Assessment (AGRRA) With the collaboration of affiliated teams in many areas of the Caribbean, Atlantic Gulf Rapid Reef Assessment (www.agrra.org) is doing major research on coral disease and coral bleaching. Its research has produced maps outlining coral populations, disease (www.agrra.org/coral-disease-outbreak) and bleaching (www.agrra.org/coral-bleaching), as well as providing reports based on surveys of coral colonies by government staff, nonprofit organizations, and volunteers. Volunteers such as cruisers and concerned locals reporting their findings have significantly expanded its research.
Additionally, AGRRA supports a digital dashboard tool, the Interactive Caribbean SCTLD Dashboard(https://bit.ly/3AuDUMN). This includes maps and statistics on countries affected, management response activities, and survey data sheets. The pattern seen for SCTLD spread in the Caribbean is very informative.
• The Puerto Rico Department of Natural and Environmental Resources This department has implemented a Coral Reef Emergency Response and Outreach program that includes a coral program website, field response guides and YouTube channels. See https://bit.ly/3GYYPu7.
• USVI Coral Disease Advisory Committee Coral research In the US Virgin Islands is supported by the University of the Virgin Islands, and is spearheaded by the USVI Coral Disease Advisory Committee (www. vicoraldisease.org). The site has reports, resources, and digital dashboards with program information. Find the USVI Digital Disease Tracking Desktop at www.vicoraldisease.org/ sctld-disease-tracking. The link includes maps with over 467 citizen science reports between 2019 and 2022, with 1,157 completed surveys.
For response and intervention, there is the USVI Strike Team Interventions Dashboard (www.vicoraldisease.org/sctld-strike-teams). The strike teams include specially trained divers implementing the latest interventions shown to be effective against SCTLD disease, including the application of antibiotic paste developed specifically for corals. The members of these teams are also assigned to investigate reported sightings.
HOW YOU CAN HELP
Don’t spread it!
Stony coral tissue loss disease is water-borne. As a boater, be aware of how to prevent the spread of the disease: for example, if you have been in areas with SCTLD don’t pump out bilge water or holding tanks near coral reefs in other areas. You might also encounter reefs that are being quarantined and where access for visitors is temporarily affected; please respect this. Divers and snorkelers, see the excellent tips
Do report it!
Private citizens’ observations — many eyes under the water — will assist in the identification of disease spread. Reporting can also help identify progress in treatment efforts. If you suspect that you might have seen the coral disease, you can help researchers by taking photos of the coral and surrounding reef, noting the location and reporting your sighting. If you see tagged corals, please take date-stamped photos showing the tag and submit with location to the local coral reef managers.
One of the ways concerned citizens can report sightings and observations is via the AGRRA experimental-interventions website tool at www.agrra.org/experimental-interventions. Fill out the online survey form, providing as much information as possible regarding the coral species affected and the location, and upload any photos.
Alternatively, interested persons can email information to [email protected]
Other sites that welcome citizen scientist observations are:
The Florida SEAFAN reporting system: https://bit.ly/3KGXdXW.
The VI_CDAC reporting system: https://bit.ly/3577NHt.
The Seven Seas Cruising Association (www.ssca.org) will submit Stony Coral Tissue Loss Disease as a key 2022 Clean Wake priority project and will collaborate with some of the organizations mentioned in this article. The Clean Wake projects focus on environmental and critical emergent needs of communities impacted by climate changes or emergencies, support citizen scientist efforts, and act as a focal point for cruisers interested in offering their talents wherever they roam.
Further articles in Compass will explore more ways that boaters can get involved by providing unique observations and assistance.
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