Stony coral tissue loss disease

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Brain coral affected by SCTLD. Stony coral tissue loss disease 01.jpg
Brain coral affected by SCTLD.
Elkhorn coral seems to be immune to SCTLD. Elkhorn coral.jpg
Elkhorn coral seems to be immune to SCTLD.

Stony coral tissue loss disease (SCTLD) is a disease of corals that first appeared off the southeast coast of Florida in 2014. It originally was described as white plague disease. [1] By 2019 it had spread along the Florida Keys and had appeared elsewhere in the Caribbean Sea. The disease destroys the soft tissue of at least 22 species of reef-building corals, [2] killing them within weeks or months of becoming infected. The causal agent is unknown but is suspected to be either a bacterium or a virus with a bacterium playing a secondary role. The degree of susceptibility of a coral, the symptoms, and the rate of progression of the disease vary between species. [3] Due to its rapid spread, high mortality rate, and lack of subsidence, it has been regarded as the deadliest coral disease ever recorded, with wide-ranging implications for the biodiversity of Caribbean coral reefs. [4]

Contents

History

The disease was first detected in late 2014 when a few corals off Virginia Key, in Miami-Dade County, Florida, were affected. By the following year, the disease had spread and extended from Pompano Beach to Biscayne National Park. In 2016 it reached Palm Beach County, Florida, and the upper Florida Keys, and the next year the lower Florida Keys. By August 2018, the disease had spread over 150 sq mi (388 km2) of sea, and almost half the species of coral growing in the Florida Reef Tract had been affected. [5] By January 2019 it had been reported from Jamaica, the Mexican Caribbean, Saint Maarten, and Saint Thomas, U.S. Virgin Islands. [3] It has since spread along the Lesser Antilles, and as of 2023, it has been reported as far south as Curacao. [6]

A 2021 study suggested that the spread of the disease is likely facilitated by ballast water from ships, due to several cases of the disease crossing currents in the opposite direction that they would flow. [7]

Data from the United States Virgin Islands shows that populations of susceptible corals and crustose coralline algae have been reduced by this disease, being replaced by fire coral, cyanobacteria, and macroalgae. A structural equation model spanning the Caribbean evinced versatility in reef fish, showing they associated with rugosity without regard for whether the coral was alive or dead. However, some declines due to stony coral tissue loss disease were still projected by the model, especially due to coral die-offs and loss of rugosity. [8]

Signs

The signs of this disease are somewhat variable, and it may be difficult to distinguish from other coral diseases. SCTLD manifests as rapidly expanding lesions on the coral. [9] Sometimes the infection exhibits a series of blotches that radiate outwards and coalesce. Small corals may be killed within weeks while larger individuals may survive for months or even a year or two. [3]

Research

This is a particularly deadly coral disease with mortality rates varying between 66% and 100%. Although the cause of the disease has not yet been established, evidence suggests that a bacterial pathogen is being transmitted either by contact or by means of water movement. Not all corals are susceptible to the disease, with staghorn coral (Acropora cervicornis) and elkhorn coral (Acropora palmata), both of which are critically endangered, appearing to be immune. [5]

A 2021 study by the Florida Fish and Wildlife Conservation Commission and U.S. Geological Survey involving electron microscopy of infected corals suggests that SCTLD may not be caused a bacterial agent as previously thought, but rather a virus that lethally affects the zooxanthellae of corals and leads to host cell death. In diseased corals, no pathologies were noted in the coral host cells aside from lysis, whereas zooxanthellae displayed chloroplast pathologies and potential single-stranded RNA viruses similar to those found in plant viruses. This may explain why amoxicillin paste, the only known effective treatment method, suppresses the growth of new lesions but does not prevent new lesions from forming. Given that amoxicillin is intended for bacteria, its apparent suppression of SCTLD lesions may be an unintended side-effect that affects the virus rather than actual suppression of a bacterial agent. [10] [11] Other studies instead suggest that the bacterium plays a secondary role in attacking weakened corals. Three strains of harmful bacteria are associated with the disease. [12]

A 2023 study developed a potential probiotic treatment for SCTLD, obtained from Pseudoalteromonas bacteria isolated from SCTLD-resistant Montastraea corals. This may provide a more effective and efficient treatment compared to amoxicillin, which requires direct application, does not prevent reinfection, and may promote antibiotic resistance in the causal agent. [13] [12]

Susceptibility

The first species on a reef to be infected are usually the meandroid corals such as pillar coral (Dendrogyra cylindrus), elliptical star coral (Dichocoenia stokes), smooth flower coral (Eusmilia fastigiata), and maze corals (Meandrina spp.). Other susceptible species include boulder brain coral (Colpophyllia natans), grooved brain coral (Diploria labyrinthiformis), maze coral (Meandrina meandrites), symmetrical brain coral (Pseudodiploria strigosa) and knobby brain coral (Pseudodiploria clivosa). [14] The genetically distinct Florida population of pillar coral has been essentially extirpated in the wild, and now primarily survives only in captivity. [15]

Limited lab experiments suggest that Indo-Pacific coral species may also be susceptible to this disease as many of them are of the same groups present in the Caribbean, which could have severe consequences if the disease happened to reach the Indo-Pacific via the Panama Canal. [16] [17] In contrast, other studies suggest that if SCTLD is of viral origins, the zooxanthellae clades inhabiting the Caribbean may be uniquely susceptible to it, in contrast to the Indo-Pacific, which is dominated by a different clade of zooxanthellae and has not seen major coral diseases. [11]

Conservation

Due to the wide-ranging effects of the disease, many of the susceptible coral species have had fragments harvested from the wild, which have then been taken into captivity across the United States for the purpose of conservation, captive breeding and selective breeding, until either conditions improve or the captive corals develop resilience to the disease. [18]

Related Research Articles

<span class="mw-page-title-main">Pillar coral</span> Species of coral

Pillar coral is a hard coral found in the western Atlantic Ocean and the Caribbean Sea. It is the only species in the monotypic genus Dendrogyra. It is a digitate coral -that is, it resembles fingers or a cluster of cigars, growing up from the sea floor without any secondary branching. It is large and can grow on both flat and sloping surfaces at depths down to 20 m (65 ft). It is one of the few types of hard coral in which the polyps can commonly be seen feeding during the day.

<span class="mw-page-title-main">Staghorn coral</span>

The Staghorn coral is a branching, stony coral, within the Order Scleractinia. It is characterized by thick, upright branches which can grow in excess of 2 meters in height and resemble the antlers of a stag, hence the name, Staghorn. It grows within various areas of a reef but is most commonly found within shallow fore and back reefs, as well as patch reefs, where water depths rarely exceed 20 meters. Staghorn corals can exhibit very fast growth, adding up to 5 cm in new skeleton for every 1 cm of existing skeleton each year, making them one of the fastest growing fringe coral species in the Western Atlantic. Due to this fast growth, Acropora cervicornis, serve as one of the most important reef building corals, functioning as marine nurseries for juvenile fish, buffer zones for erosion and storms, and center points of biodiversity in the Western Atlantic.

<span class="mw-page-title-main">Elkhorn coral</span> Species of coral

Elkhorn coral is an important reef-building coral in the Caribbean. The species has a complex structure with many branches which resemble that of elk antlers; hence, the common name. The branching structure creates habitat and shelter for many other reef species. Elkhorn coral is known to grow quickly with an average growth rate of 5 to 10 cm per year. They can reproduce both sexually and asexually, though asexual reproduction is much more common and occurs through a process called fragmentation.

<span class="mw-page-title-main">Yellow-band disease</span> Bacterial disease of coral

Yellow-band disease is a coral disease that attacks colonies of coral at a time when coral is already under stress from pollution, overfishing, and climate change. It is characterized by large blotches or patches of bleached, yellowed tissue on Caribbean scleractinian corals.

<span class="mw-page-title-main">Environmental issues with coral reefs</span> Factors which adversely affect tropical coral reefs

Human activities have substantial impact on coral reefs, contributing to their worldwide decline.[1] Damaging activities encompass coral mining, pollution, overfishing, blast fishing, as well as the excavation of canals and access points to islands and bays. Additional threats comprise disease, destructive fishing practices, and the warming of oceans.[2] Furthermore, the ocean's function as a carbon dioxide sink, alterations in the atmosphere, ultraviolet light, ocean acidification, viral infections, the repercussions of dust storms transporting agents to distant reefs, pollutants, and algal blooms represent some of the factors exerting influence on coral reefs. Importantly, the jeopardy faced by coral reefs extends far beyond coastal regions. The ramifications of climate change, notably global warming, induce an elevation in ocean temperatures that triggers coral bleaching—a potentially lethal phenomenon for coral ecosystems.

The resilience of coral reefs is the biological ability of coral reefs to recover from natural and anthropogenic disturbances such as storms and bleaching episodes. Resilience refers to the ability of biological or social systems to overcome pressures and stresses by maintaining key functions through resisting or adapting to change. Reef resistance measures how well coral reefs tolerate changes in ocean chemistry, sea level, and sea surface temperature. Reef resistance and resilience are important factors in coral reef recovery from the effects of ocean acidification. Natural reef resilience can be used as a recovery model for coral reefs and an opportunity for management in marine protected areas (MPAs).

<i>Diploria</i> Genus of corals

Diploria is a monotypic genus of massive reef building stony corals in the family Mussidae. It is represented by a single species, Diploria labyrinthiformis, commonly known as grooved brain coral and is found in the western Atlantic Ocean and Caribbean Sea. It has a familiar, maze-like appearance.

<i>Colpophyllia</i> Genus of corals

Colpophyllia is a genus of stony corals in the family Mussidae. It is monotypic with a single species, Colpophyllia natans, commonly known as boulder brain coral or large-grooved brain coral. It inhabits the slopes and tops of reefs, to a maximum depth of fifty metres. It is characterised by large, domed colonies, which may be up to two metres across, and by the meandering network of ridges and valleys on its surface. The ridges are usually brown with a single groove, and the valleys may be tan, green, or white and are uniform in width, typically 2 centimetres. The polyps only extend their tentacles at night.

<i>Pseudodiploria clivosa</i> Species of coral

Pseudodiploria clivosa, the knobby brain coral, is a colonial species of stony coral in the family Mussidae. It occurs in shallow water in the West Atlantic Ocean and Caribbean Sea.

<i>Scolymia lacera</i> Species of coral

Scolymia lacera, the fleshy disk coral, is a species of stony coral in the family Mussidae. It occurs on reefs in shallow waters in the Caribbean Sea, the Gulf of Mexico, the Bahamas, Bermuda and southern Florida.

<i>Porites porites</i> Species of coral

Porites porites, commonly known as hump coral or finger coral, is a species of stony coral in the genus Porites. It is found in the Caribbean Sea and western Atlantic Ocean and also along the coast of West Africa.

<i>Dichocoenia</i> Genus of corals

Dichocoenia is a monotypic genus of stony coral in the family Meandrinidae. It is represented by a single species, Dichocoenia stokesii, which is commonly known as pineapple coral, elliptical star coral, or pancake star coral. It is mostly found in the Caribbean Sea and the western Atlantic Ocean. Dichocoenia stokesii has irregular calyces and its form can be either a massive, hemispherical hump or a flat, platform-like structure.

<i>Meandrina meandrites</i> Species of coral

Meandrina meandrites, commonly known as maze coral, is a species of colonial stony coral in the family Meandrinidae. It is found primarily on outer coral reef slopes in the Caribbean Sea and the Gulf of Mexico.

<i>Mussa angulosa</i> Species of coral

Mussa is a genus of stony coral in the family Faviidae. It is monotypic, being represented by the single species Mussa angulosa, commonly known as the spiny or large flower coral. It is found on reefs in shallow waters in the Caribbean Sea, the Bahamas and the Gulf of Mexico.

<span class="mw-page-title-main">Mesophotic coral reef</span>

A mesophotic coral reef or mesophotic coral ecosystem (MCE), originally from the Latin word meso (meaning middle) and photic (meaning light), is characterized by the presence of both light-dependent coral and algae, and organisms that can be found in water with low light penetration. Mesophotic coral ecosystems occur at depths beyond those typically associated with coral reefs as the mesophotic ranges from brightly lit to some areas where light does not reach. Mesophotic coral ecosystem (MCEs) is a new, widely-adopted term used to refer to mesophotic coral reefs, as opposed to other similar terms like "deep coral reef communities" and "twilight zone", since those terms sometimes are confused due to their unclear, interchangeable nature. Many species of fish and corals are endemic to the MCEs making these ecosystems a crucial component in maintaining global diversity. Recently, there has been increased focus on the MCEs as these reefs are a crucial part of the coral reef systems serving as a potential refuge area for shallow coral reef taxa such as coral and sponges. Advances in recent technologies such as remotely operated underwater vehicles (ROVs) and autonomous underwater vehicles (AUVs) have enabled humans to conduct further research on these ecosystems and monitor these marine environments.

<i>Orbicella faveolata</i> Species of coral

Orbicella faveolata, commonly known as mountainous star coral, is a colonial stony coral in the family Merulinidae. Orbicella faveolata is native to the coral coast of the Caribbean Sea and the Gulf of Mexico and is listed as "endangered" by the International Union for Conservation of Nature. O. faveolata was formerly known as Montastraea faveolata.

<i>Agaricia tenuifolia</i> Species of coral

Agaricia tenuifolia, commonly known as thin leaf lettuce coral, is a species of colonial stony coral in the family Agariciidae. This coral is found in shallow waters in the Caribbean Sea and Gulf of Mexico.

<span class="mw-page-title-main">Corallivore</span> Animal that feeds on coral

A corallivore is an animal that feeds on coral. Corallivores are an important group of reef organism because they can influence coral abundance, distribution, and community structure. Corallivores feed on coral using a variety of unique adaptations and strategies. Known corallivores include certain mollusks, annelids, fish, crustaceans, flatworms and echinoderms. The first recorded evidence of corallivory was presented by Charles Darwin in 1842 during his voyage on HMS Beagle in which he found coral in the stomach of two Scarus parrotfish.

White plague is a suite of coral diseases of which three types have been identified, initially in the Florida Keys. They are infectious diseases but it has proved difficult to identify the pathogens involved. White plague type II may be caused by the gram negative bacterium Aurantimonas coralicida in the order Hyphomicrobiales but other bacteria have also been associated with diseased corals and viruses may also be implicated.

References

  1. ↑ Precht, William F.; Gintert, Brooke E.; Robbart, Martha L.; Fura, Ryan; van Woesik, Robert (2016-08-10). "Unprecedented Disease-Related Coral Mortality in Southeastern Florida". Scientific Reports. 6 (1): 31374. Bibcode:2016NatSR...631374P. doi:10.1038/srep31374. ISSN   2045-2322. PMC   4979204 . PMID   27506875.
  2. ↑ Meiling, Sonora S.; Muller, Erinn M.; Lasseigne, Danielle; Rossin, Ashley; Veglia, Alex J.; MacKnight, Nicholas; Dimos, Bradford; Huntley, Naomi; Correa, Adrienne M. S.; Smith, Tyler Burton; Holstein, Daniel M. (2021). "Variable Species Responses to Experimental Stony Coral Tissue Loss Disease (SCTLD) Exposure". Frontiers in Marine Science. 8. doi: 10.3389/fmars.2021.670829 . hdl: 1912/27453 . ISSN   2296-7745.
  3. 1 2 3 "Florida Reef Tract Coral Disease Outbreak: Disease". Florida Keys National Marine Sanctuary. NOAA. Retrieved 15 May 2019.
  4. ↑ Trinidad, Jewel Fraser in Port-of-Spain (2021-07-22). "Deadly coral disease sweeping Caribbean linked to water from ships". the Guardian. Retrieved 2021-09-07.
  5. 1 2 Weinberg, Elizabeth (1 August 2018). "Scientists work together to solve a coral disease mystery in Florida Keys National Marine Sanctuary". National Marine Sanctuaries. Retrieved 15 May 2019.
  6. ↑ Herald, Alex Harris, Miami. "Can probiotics cure Florida's ailing coral reefs? Tests show it works on devastating disease". The Brunswick News. Retrieved 2023-04-25.{{cite web}}: CS1 maint: multiple names: authors list (link)
  7. ↑ Dahlgren, Craig; Pizarro, Valeria; Sherman, Krista; Greene, William; Oliver, Joseph (2021). "Spatial and Temporal Patterns of Stony Coral Tissue Loss Disease Outbreaks in The Bahamas". Frontiers in Marine Science. 8. doi: 10.3389/fmars.2021.682114 . ISSN   2296-7745.
  8. ↑ Swaminathan, Sara D.; Lafferty, Kevin D.; Knight, Nicole S.; Altieri, Andrew H. (2024-05-03). "Stony coral tissue loss disease indirectly alters reef communities". Science Advances. 10 (18). doi:10.1126/sciadv.adk6808. ISSN   2375-2548.
  9. ↑ SCTLD Case Definition (2018). Florida Coral Disease Response Research & Epidemiology Team. Available online at: https://floridadep.gov/sites/default/ files/Copy%20of%20StonyCoralTissueLossDisease_CaseDefinition%20final% 2010022018.pdf (accessed October 6, 2020).
  10. ↑ Connolly, Norma (2021-08-13). "Research sheds new light on stony coral disease". Cayman Compass. Retrieved 2021-09-07.
  11. 1 2 Work, Thierry M. (June 15, 2021). "Final report on electron microscopy of Florida corals affected with stony coral tissue loss disease (SCTLD)" (PDF).
  12. 1 2 Magazine, Smithsonian; Handwerk, Brian. "Probiotics May Help Corals Fight a Dangerous Disease Off Florida's Coast". Smithsonian Magazine. Retrieved 2023-04-25.
  13. ↑ Ushijima, Blake; Gunasekera, Sarath P.; Meyer, Julie L.; Tittl, Jessica; Pitts, Kelly A.; Thompson, Sharon; Sneed, Jennifer M.; Ding, Yousong; Chen, Manyun; Jay Houk, L.; Aeby, Greta S.; Häse, Claudia C.; Paul, Valerie J. (2023-04-06). "Chemical and genomic characterization of a potential probiotic treatment for stony coral tissue loss disease". Communications Biology. 6 (1): 248. doi:10.1038/s42003-023-04590-y. ISSN   2399-3642. PMC   10079959 . PMID   37024599.
  14. ↑ "Stony coral tissue loss disease". International Coral Reef Initiative. Retrieved 15 May 2019.
  15. ↑ Jones, Nicholas P.; Kabay, Lystina; Semon Lunz, Kathleen; Gilliam, David S. (2021-07-08). "Temperature stress and disease drives the extirpation of the threatened pillar coral, Dendrogyra cylindrus, in southeast Florida". Scientific Reports. 11 (1): 14113. Bibcode:2021NatSR..1114113J. doi:10.1038/s41598-021-93111-0. ISSN   2045-2322. PMC   8266880 . PMID   34238939.
  16. ↑ "This Deadly Coral Disease Is Threatening More Than Just Reefs". Bloomberg.com. 2021-06-03. Retrieved 2021-09-07.
  17. ↑ US Department of Commerce, National Oceanic and Atmospheric Administration. "NOAA Coral Reef Conservation Program - Guam Green Growth Initiative (G3)". coralreef.noaa.gov. Retrieved 2021-09-07.
  18. ↑ Tomassoni, Teresa. "The race to rescue Florida's diseased corals". Washington Post. Retrieved 2021-09-07.
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