White band disease

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White band disease
Other namesAcroporid white syndrome
Whitebanddiseasecoral.jpg
White band disease affecting elkhorn coral ("Acropora palmata") in Africa.
Specialty Marine biology

White band disease is a coral disease that affects acroporid corals and is distinguishable by the white band of exposed coral skeleton that it forms. [1] The disease completely destroys the coral tissue of Caribbean acroporid corals, specifically elkhorn coral (Acropora palmata) and staghorn coral (A. cervicornis). [1] The disease exhibits a pronounced division between the remaining coral tissue and the exposed coral skeleton. [2] These symptoms are similar to white plague, except that white band disease is only found on acroporid corals, and white plague has not been found on any acroporid corals. [3] It is part of a class of similar disease known as "white syndromes", many of which may be linked to species of Vibrio bacteria. While the pathogen for this disease has not been identified, Vibrio carchariae may be one of its factors. The degradation of coral tissue usually begins at the base of the coral, working its way up to the branch tips, but it can begin in the middle of a branch. [1]

Contents

Appearance

White Syndrome in the Indo-Pacific

White band disease causes the affected coral tissue to spin off the skeleton in a white uniform band for which the disease was given its name. [4] The band, which can range from a few millimeters to 10 centimeters wide, typically works its way from the base of the coral colony up to the coral branch tips. [5] The band progresses up the coral branch at an approximate rate of 5 millimeters per day, causing tissue loss as it works its way to the branch tips. [1] After the tissue is lost, the bare skeleton of the coral may later by colonized by filamentous algae. [6]

There are two variants of white band disease, type I and type II. [4] In Type I of white band disease, the tissue remaining on the coral branch shows no sign of coral bleaching, although the affected colony may appear lighter in color overall. [4] However, a variant of white band disease, known simply as white band disease Type II, which was found on Staghorn colonies near the Bahamas, does produce a margin of bleached tissue before it is lost. [7] Type II of white band disease can be mistaken for coral bleaching. [7] By examining the remaining living coral tissue for bleaching, one can delineate which type of the disease affects a given coral. [7]

Pathogen

No known pathogen has been isolated (it has only been attempted for type II) for white band disease, although there is a shift of bacterial composition in the surface layer where the band eats away as the coral tissue. [8] The bacteria shifts from a dominant pseudomonad population to an increasingly dominant Vibrio carchariae population. [9] [10] Histopathological examinations of diseased tissue provide some insight into the specific pathogen or combination of pathogens that cause this disease. [5] However, substantial samples of rickettsiales have been present in the surface layer, which causes scientists to suspect that this bacteria may be one of the factors of the disease. [5] [10]

The disease, however, typically begins from the base of the coral and works its way up the coral branches. [1] As it progresses, the band leaves behind the white coral skeleton. [4] Many of the details of how the breakdown of coral occurs due to the bacteria are unclear mainly in part to the difficulty in isolating marine bacteria. [8] Studies have confirmed that white band disease is contagious and caused by a pathogenic bacteria. [8] Experiments have shown that Ampicillin may be able to treat white band disease type I. [8]

Impact and range

Since white band disease was first reported in the 1970s, the disease has led to the devastation of approximately 95% of the elkhorn and staghorn corals in the Caribbean region. [1] This resulted in both affected species being listed as threatened under the US Endangered Species Act and as critically endangered on the IUCN Red List. [6] The decline in these corals has a lasting effect on both humans and the environment. [11] Coral reefs protect coastlines from ocean currents, waves, and storms, and the death of these corals only increases the loss of coastlines in affected regions. [12] Elkhorn and staghorn corals are two of the major reef-building corals, the foundation on which the rest of the coral reef is formed. [11] Its loss means the loss of a habitat for many coral reef dwelling species such as lobsters, parrot-fish, snapper shrimps, and many other reef species, causing a sharp decline in the biodiversity of an affected region. [13] Coral reefs are also home to more than twenty-five percent of all marine fish species, making them extremely biologically diverse. [13] The loss of this coral would be particularly damaging to people living on the coast in terms of the food supply, coastal protection, economic security and more. [12] Nearly 500 million people directly depend on coral reefs for food and income (through tourism or otherwise). [12]

Elkhorn coral absorbs much carbon dioxide from the ocean every year, preventing ocean acidification and ocean temperature increases. [14] Upon decomposing, Elkhorn coral releases its sequestered carbon dioxide back into the ocean, heating it and contributing to acidification. [11] [14] White band disease threatens more than just the coral with its lethal touch. In recent decades, the coral cover in coral reefs has been declining, providing for a transitional increase in the fleshy macroalgae cover in the Caribbean region as more and more filamentous algae colonize inside of the coral skeletons. [6] The death of elkhorn and staghorn corals also substantially reduces coral cover and provides substratum space for further algal growth. [6] Prospects are poor for the recovery of the elkhorn coral, given its asexual method of reproduction, which relies on coral fragments breaking off from the main body and growing in a new area. [6] Staghorn coral also relies on asexual fragmentation as its primary method of reproduction, however, staghorn coral possesses a higher rate of sexual recruitment than Elkhorn coral. [6]

White band disease has been reported most notably in the Caribbean region. [6] However, white band disease has also been sighted in the Red Sea, and the Indo-Pacific region, including the Philippines, the Great Barrier Reef, and Indonesia. [15] Unlike white band disease in the Caribbean region, white band disease in the Indo-Pacific region has been found on approximately 34 species of massive, branching and plating corals instead of just simply Elkhorn and Staghorn corals. [15]

Transmission

White band disease is highly contagious through direct contact between diseased and healthy coral tissue. [10] It can also be transmitted by the corallivorous snail, which means that the species consumes coral, Coralliophila abbreviata. [10] C. abbreviata, a species native to the region where Elkhorn and Staghorn corals are found, is able to act as a "reservoir" for white band disease, meaning that it is able to retain the disease pathogen for at least two weeks. [10] However, not all corallivorous snails are able to transmit white band disease (i.e. Coralliophila caribaea). [10] Waterborne transmission of the disease pathogen becomes possible when the coral tissue is lesioned (or otherwise injured). [10] However, the potential for injury among the affected corals tends to be high given the many ways tissue injury may occur naturally including competition by other corals, mechanical damage, or corallivory by snails, damselfish, butterflyfish, fireworms, or other such aquatic organisms. [10] Waterborne transmission helps to explain how the disease spread across the Caribbean so rapidly, given that direct contact between affected corals is limited to physical interaction between the diseased and healthy coral and that the corallivorous snail, C. abbreviata that carries the disease, does not travel across long distances. [10]

Insights into the nature of white band disease transmission provide understanding of how the disease might be managed and controlled to prevent major losses in coral. [10] Waterborne transmission of white band disease may prove difficult to manage however, given the flowing nature of ocean currents. [10] An alternative method would be to control C. abbreviata populations to reduce the incidence of white band disease by manually removing samples of the population, similar to efforts to remove Pterois from the Gulf of Mexico. [10]

Effects of climate change

White band disease prevalence in the Caribbean varies seasonally. [10] It is more active in summer and less prominent in winter, suggesting that warmer water temperatures contribute to the waterborne spread of the disease to affected corals. [10] The impacts of climate change and increasing carbon emissions only serve to heat the waters surrounding the coral reef ecosystems, which may allow for the spread of diseases such as white band disease and others. [14] The severity of marine diseases such as white band disease increase for several reasons. Elevated water temperature can cause corals physiological stress. [14] This possibly undermines their immune systems and makes them more susceptible to infection from white band disease or other coral diseases. [14] Furthermore, elevated temperatures make bacterial and fungal pathogens much more virulent. However, the disease is not limited to elevated water temperatures as white band disease can still be prevalent even when water temperatures are cool. [10] [13] [14]

Anthropogenic climate change is negatively impacting the world's corals and coral reef ecosystems. Over the next few decades as climate change continues, oceanic warming and acidification will accelerate and further damage the fragile reef ecosystems. [14] Prediction of the impacts of future climate change on coral reefs can be difficult given the uncertainty in certain involved socioeconomic factors (i.e. political response, future technology, changes in human behavior, the Earth's climate system, and the realtime effects on coral reefs). [14] Despite these uncertainties, humans could see the extinction of the coral reef ecosystem by the end of the 21st century if actions are not taken to protect them. [14] According to forecast models of increasing oceanic temperature, mass mortality events will likely occur as early as the summer of 2030 and continue to occur on an annual basis. [13] [14]

See also

Related Research Articles

<span class="mw-page-title-main">Black band disease</span> Coral disease

Black band disease is a coral disease in which corals develop a black band. It is characterized by complete tissue degradation due to a pathogenic microbial consortium. The mat is present between apparently healthy coral tissue and freshly exposed coral skeleton.

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

The staghorn coral is a branching, stony coral with cylindrical branches ranging from a few centimetres to over two metres in length and height. It occurs in back reef and fore reef environments from 0 to 30 m depth. Wave forces dictate the upper threshold, while suspended sediments and the availability of light regulate the lower boundary. Until the mid-1980s, the intermediate depths of 5–25 meters in the fore reef zones were once primarily occupied by vast areas of staghorn coral, consisting largely of single-species stands. This coral exhibits the fastest growth of all known western Atlantic fringe corals, with branches increasing in length by 10–20 cm (3.9–7.9 in) per year. This has been one of the three most important Caribbean corals in terms of its contribution to reef growth and fishery habitat.

<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.

Skeletal eroding band (SEB) is a disease of corals that appears as a black or dark gray band that slowly advances over corals, leaving a spotted region of dead coral in its wake. It is the most common disease of corals in the Indian and Pacific Oceans, and is also found in the Red Sea.

<span class="mw-page-title-main">Florida Reef</span> Coral barrier reef along the Florida Keys

The Florida Reef is the only living coral barrier reef in the continental United States. It lies a few miles seaward of the Florida Keys, is about 4 miles wide and extends 270 km (170 mi) from Fowey Rocks just east of Soldier Key to just south of the Marquesas Keys. The barrier reef tract forms a great arc, concentric with the Florida Keys, with the northern end, in Biscayne National Park, oriented north-south and the western end, south of the Marquesas Keys, oriented east-west. The rest of the reef outside Biscayne National Park lies within John Pennekamp Coral Reef State Park and the Florida Keys National Marine Sanctuary. Isolated coral patch reefs occur northward from Biscayne National Park as far north as Stuart, in Martin County. Coral reefs are also found in Dry Tortugas National Park west of the Marquesas Keys. There are more than 6,000 individual reefs in the system. The reefs are 5,000 to 7,000 years old, having developed since sea levels rose following the Wisconsinan glaciation.

<span class="mw-page-title-main">White pox disease</span> Disease of coral

White pox disease, first noted in 1996 on coral reefs near the Florida keys, is a coral disease affecting Elkhorn coral throughout the Caribbean. It causes irregular white patches or blotches on the coral that result from the loss of coral tissue. These patches distinguish white pox disease from white band disease which produces a distinctive white band where the coral skeleton has been denuded. The blotches caused by this disease are also clearly differentiated from coral bleaching and scars caused by coral-eating snails. It is very contagious, spreading to nearby coral.

<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.

<i>Acropora prolifera</i> Species of coral

Acropora prolifera, the fused staghorn coral, is a branching, colonial, stony coral found in shallow parts of the Caribbean Sea, the Bahamas and southern Florida.

<i>Acropora pulchra</i> Species of coral

Acropora pulchra is a species of colonial staghorn coral in the family Acroporidae. It is found on the back fringes of reefs in shallow water in the western Indo-Pacific Ocean. The oldest fossils of this species date back to the Pleistocene.

<i>Acropora muricata</i> Species of coral

Acropora muricata, commonly called staghorn coral, is a species of acroporid coral found in the Gulf of Aden, the Red Sea, Indian Ocean, Persian Gulf, Australia, central Indo-Pacific, Japan, Southeast Asia, the East China Sea and the oceanic central and western Pacific Ocean. It is found in tropical shallow reefs, slopes of reefs, and in lagoons, from depths of 5 to 30 m. It was described by Dana in 1846.

Acropora dendrum is a species of acroporid coral that was first described by Bassett-Smith in 1890. Found in tropical, shallow reefs in areas of powerful waves at depths of 5 to 20 m, it is threatened by disease. The species is rated as vulnerable on the IUCN Red List, with a decreasing population. It is not common but found over a large area, and is listed on CITES Appendix II.

Acropora derawanensis is a species of acroporid coral that was first described by Carden Wallace in 1997. Found in tropical, shallow reefs sheltered from the waves in a marine environment, it is found at depths of 10 to 25 m on reef slopes. The species is rated as vulnerable on the IUCN Red List, with a decreasing population. It is not common but found over a large area, and is listed on CITES Appendix II. It is easily damaged.

<i>Acropora donei</i> Species of coral

Acropora donei is a species of acroporid coral that was first described by J. Veron and Carden Wallace in 1984. Found in fringing reefs and the upper slopes of shallow reefs, it occurs at depths of 5 to 20 m. The species is rated as vulnerable on the IUCN Red List, with a decreasing population, and is affected by disease. It is not common but found over a large area, and is listed under CITES Appendix II.

Acropora kirstyae is a species of acroporid coral that was first described by Jen Veron and C. C. Wallace in 1984. Found in marine, tropical, shallow reefs in sheltered areas usually at depths of 10 to 25 m, and also occurs in sheltered lagoons. It is listed as a vulnerable species on the IUCN Red List, and it is thought to have a decreasing population. It is not common and found over a large area, and is listed on CITES Appendix II.

Acropora kosurini is a species of acroporid coral that was first described by C. C. Wallace in 1994. Found in marine, shallow reefs, it occurs at depths of 8 to 20 m. It is listed as a vulnerable species on the IUCN Red List, and it is believed to have a decreasing population. It is rare but found over a large area, and is listed on CITES Appendix II.

<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.

Coral diseases are transmissible pathogens that cause the degradation of coral colonies. Coral cover in reef ecosystems has decreased significantly for a diverse set of reasons, ranging from variable environmental conditions to mechanical breakdowns from storms. In recent years, diseases that infect and kill coral have shown to be a threat to the health of coral reefs. Since the first coral disease was reported in 1965, many different kinds of diseases have popped up in mostly Caribbean waters. These diseases are diverse, including pathogens of bacteria, fungi, viruses, and protozoans. Coral diseases have widespread implications, impacting entire ecosystems and communities of organisms. Researchers are working to understand these diseases, and how potential treatments could stop these pathogens from causing the widespread death of corals in a way that permanently impacts the community structure of reefs.

<span class="mw-page-title-main">Stony coral tissue loss disease</span> Disease affecting corals

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. 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, 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. 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.

<span class="mw-page-title-main">Coral reefs of Jamaica</span>

Jamaica, an island located within the Caribbean Sea, known for being a popular tourist destination because of its pristine white sand beaches, is now faced with the issue of mass coral depletion. Both environmental and human factors contribute to the destruction of these corals, which inevitably affect Jamaica's environmental sustainability and economy. Actions have been put in place to counteract the negative consequences associated with the loss of the corals, which act as a symbol of hope for the revival of Jamaica's environment.

<span class="mw-page-title-main">Kimberly Ritchie</span> American marine biologist

Kimberly B. Ritchie is an American marine biologist. She is an Associate Professor in the Department of Natural Sciences at the University of South Carolina Beaufort. Her research is focused on marine microbiology and how microbes affect animal health in hosts such as corals and sharks.

References

  1. 1 2 3 4 5 6 Gladfelter, W. B. "Population Structure of Acropora palmata on the Windward Fore Reef, Buck Island National Monument, St. Croix, U.S. Virgin Islands". U.S. Department of the Interior, National Park Service.{{cite web}}: Missing or empty |url= (help)
  2. ↑ "White band disease".
  3. ↑ Vargas-Angel, and Wheeler, Bernardo, and Benjamin. "Coral Health and Disease Assessment in the U.S. Pacific Territories and Affiliated States" (PDF).{{cite web}}: CS1 maint: multiple names: authors list (link)
  4. 1 2 3 4 "Major Reef-Building Coral Diseases". NOAA's Coral Reef Information System.
  5. 1 2 3 Peters, E. C. "Diseases of coral reef organisms". Life and Death of Coral Reefs. Chapman & Hall.{{cite web}}: Missing or empty |url= (help)
  6. 1 2 3 4 5 6 7 Aronson, R. & Precht, W., Richard B.; Precht, William F. (2001). "White-band disease and the changing face of Caribbean coral reefs". Hydrobiologia. 460: 25–38. doi:10.1023/A:1013103928980. S2CID   34863063.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. 1 2 3 Ritchie and Smith. "Type II White-Band Disease" (PDF).
  8. 1 2 3 4 Kline and Vollmer, David and Steven (2011). "White Band Disease (type I) of Endangered Caribbean Acroporid Corals is Caused by Pathogenic Bacteria". Sci Rep. 1: 7. Bibcode:2011NatSR...1E...7K. doi:10.1038/srep00007. PMC   3216495 . PMID   22355526.
  9. ↑ Ritchie and Smith. "Preferential carbon utilization by surface bacterial communities by water mass, normal, and white band diseased Acropora cervicornis" (PDF).
  10. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Gignoux-Wolfsohn, Marks, and Vollmer (2012). "White Band Disease transmission in the threatened coral, Acropora cervicornis". Scientific Reports. 2: 804. Bibcode:2012NatSR...2E.804G. doi:10.1038/srep00804. PMC   3496162 . PMID   23150775.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. 1 2 3 "Coral's Ecological Value".
  12. 1 2 3 "Coral Reefs and Climate Change: Impacts on Humans".
  13. 1 2 3 4 Jones, McCormick, Srinivasa, & Eagle, Geoffrey, Mark, Maya, & Janelle (2004). "Coral decline threatens fish biodiversity in marine reserves". Proceedings of the National Academy of Sciences of the United States of America. 101 (21): 8251–3. Bibcode:2004PNAS..101.8251J. doi: 10.1073/pnas.0401277101 . PMC   419589 . PMID   15150414.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. 1 2 3 4 5 6 7 8 9 10 Bruno, John. "Coral reefs and climate change".
  15. 1 2 Green, E. and A. W. Bruckner. "The significance of coral disease epizootiology for coral reef conservation". 96. Biological Conservation.{{cite web}}: Missing or empty |url= (help)
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