Coral disease: Difference between revisions
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'''Coral diseases''' are transmissible [[Pathogen|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.<ref name=":1">{{Cite journal |last=Harvell |first=Drew |last2=Jordán-Dahlgren |first2=Eric |last3=Merkel |first3=Susan |last4=Rosenberg |first4=Eugene |last5=Raymundo |first5=Laurie |last6=Smith |first6=Garriet |last7=Weil |first7=Ernesto |last8=Willis |first8=Bette |date=2007 |title=Coral disease, environmental drivers, and the balance between coral and microbial associates |url=http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/20_1/20.1_breaking_waves.pdf |journal=Oceanography |language=en |volume=20 |pages=172–195 |issn=1042-8275}}</ref><ref name=":4">{{Cite book |title=Diseases of coral |date=2016 |publisher=Wiley Blackwell |isbn=978-0-8138-2411-6 |editor-last=Woodley |editor-first=Cheryl M. |location=Hoboken, New Jersey |editor-last2=Downs |editor-first2=Craig A. |editor-last3=Bruckner |editor-first3=Andrew W. |editor-last4=Porter |editor-first4=James W. |editor-last5=Galloway |editor-first5=Sylvia B.}}</ref> 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|Caribbean waters]].<ref name=":0">{{Cite journal |last=Sokolow |first=S |date=2009-11-16 |title=Effects of a changing climate on the dynamics of coral infectious disease: a review of the evidence |url=http://www.int-res.com/abstracts/dao/v87/n1-2/p5-18/ |journal=Diseases of Aquatic Organisms |language=en |volume=87 |pages=5–18 |doi=10.3354/dao02099 |issn=0177-5103}}</ref> These diseases are diverse, including pathogens of [[bacteria]], [[Fungus|fungi]], [[Virus|viruses]], and [[Protozoa|protozoans]].<ref name=":1" /> Coral diseases have widespread implications, impacting entire [[Ecosystem|ecosystems]] and [[Community (ecology)|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.<ref name=":5">{{Cite journal |last=Sweet |first=Michael |last2=Jones |first2=Rachel |last3=Bythell |first3=John |date=2012-06 |title=Coral diseases in aquaria and in nature |url=https://www.cambridge.org/core/product/identifier/S0025315411001688/type/journal_article |journal=Journal of the Marine Biological Association of the United Kingdom |language=en |volume=92 |issue=4 |pages=791–801 |doi=10.1017/S0025315411001688 |issn=0025-3154}}</ref><ref name=":6">{{Cite journal |last=Pollock |first=F. Joseph |last2=Morris |first2=Pamela J. |last3=Willis |first3=Bette L. |last4=Bourne |first4=David G. |date=2011-10-20 |title=The Urgent Need for Robust Coral Disease Diagnostics |url=https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1002183 |journal=PLOS Pathogens |language=en |volume=7 |issue=10 |pages=e1002183 |doi=10.1371/journal.ppat.1002183 |issn=1553-7374 |pmc=PMC3197597 |pmid=22028646}}</ref> |
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'''Coral diseases''', comprising the diseases that affect [[coral]]s, injure the living tissues and often result in the death of part or the whole of the [[Colony (biology)|colony]]. These diseases have been occurring more frequently in the twenty-first century as conditions become more stressful for many shallow-water corals. The [[pathogen]]s causing the diseases include [[bacteria]], [[fungi]] and [[protozoa]], but it is not always possible to identify the pathogen involved. |
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==Stress factors== |
==Stress factors== |
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[[Image:Koral mozgovity hranica.jpg|thumb|right|[[Black band disease]] on a [[brain coral]] in the [[Caribbean Sea]]]] |
[[Image:Koral mozgovity hranica.jpg|thumb|right|[[Black band disease]] on a [[brain coral]] in the [[Caribbean Sea]]]] |
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Like other organisms, [[Scleractinia|stony corals]] and [[Alcyonacea|soft corals]] are subject to disease. This may not have been obvious in the past, but is becoming increasingly apparent in the twenty-first century. The rising ill health of corals is partially the result of the corals being subjected to increasing amounts of stress as the physical environment around them becomes less suited to their needs.<ref name=":12">{{Cite journal |last=Harvell |first=Drew |last2=Jordán-Dahlgren |first2=Eric |last3=Merkel |first3=Susan |last4=Rosenberg |first4=Eugene |last5=Raymundo |first5=Laurie |last6=Smith |first6=Garriet |last7=Weil |first7=Ernesto |last8=Willis |first8=Bette |date=2007 |title=Coral disease, environmental drivers, and the balance between coral and microbial associates |url=http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/20_1/20.1_breaking_waves.pdf |journal=Oceanography |language=en |volume=20 |pages=172–195 |issn=1042-8275}}</ref><ref name=":42">{{Cite book |title=Diseases of coral |date=2016 |publisher=Wiley Blackwell |isbn=978-0-8138-2411-6 |editor-last=Woodley |editor-first=Cheryl M. |location=Hoboken, New Jersey |editor-last2=Downs |editor-first2=Craig A. |editor-last3=Bruckner |editor-first3=Andrew W. |editor-last4=Porter |editor-first4=James W. |editor-last5=Galloway |editor-first5=Sylvia B.}}</ref> Corals live within a precise range of abiotic environmental conditions including water temperature, salinity and water quality. Variations outside the normal range of these parameters may make the corals less able to grow and reproduce successfully, and may make them more susceptible to diseases.<ref name=":12" /> One of the major consequences that can occur with stress is the coral expelling its [[zooxanthellae]], which are [[Mutualism (biology)|mutualistic]] [[algae]] that live inside coral. Corals without their symbionts become [[Coral bleaching|bleached]], which effectively kills them since they are unable to gain the correct nutrients without their symbionts. Corals being sensitive to stress factors makes it difficult to study diseases, because the pathogen could impact any part of the coral-symbiont [[Mutualism (biology)|mutualism]] in the same ways that environmental factors do.<ref name=":7">{{Cite journal |last=Bourne |first=David G. |last2=Garren |first2=Melissa |last3=Work |first3=Thierry M. |last4=Rosenberg |first4=Eugene |last5=Smith |first5=Garriet W. |last6=Harvell |first6=C. Drew |date=2009-12 |title=Microbial disease and the coral holobiont |url=https://linkinghub.elsevier.com/retrieve/pii/S0966842X09002078 |journal=Trends in Microbiology |language=en |volume=17 |issue=12 |pages=554–562 |doi=10.1016/j.tim.2009.09.004}}</ref> |
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[[Scleractinia|Stony corals]] and [[Alcyonacea|soft corals]] are subject to disease in the same way as other organisms. This may not have been obvious in the past but is becoming increasingly apparent in the twenty-first century. The ill health is the result of the corals being subjected to increasing amounts of stress as the physical environment in which they live becomes less suited to their needs.<ref name=Woodley/> |
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Corals live within a precise range of environmental conditions including water temperature, salinity and water quality. Variations outside the normal range of these parameters may make the corals less able to grow and reproduce successfully. Of themselves these variations may be insufficient to kill the corals, but they make them more susceptible to disease organisms. The main factor that causes stress to the corals is [[climate change]], with an increase in [[sea temperature]]s, particularly affecting shallow-water corals in the tropics. One of the consequences of heat stress is that the coral expels its [[zooxanthellae]] and becomes [[Coral bleaching|bleached]]. The rise in sea temperature is also expected to increase the frequency and severity of tropical storms; these adversely affect corals through mechanical damage to reefs, through increased wave action, and through the stirring up and re-deposition of sediment.<ref name=Woodley>{{cite book|author1=Woodley, Cheryl M. |author2=Downs, Craig A.|author3=Bruckner, Andrew W.|author4=Porter, James W.|author4-link=James W. Porter (ecologist)|author5=Galloway, Sylvia B.|title=Diseases of Coral |url=https://books.google.com/books?id=U8gbCQAAQBAJ |date=2016 |publisher=John Wiley & Sons |isbn=978-0-8138-2411-6 |pages=1–2}}</ref> Other stress factors include increased [[pollution]], increased [[ultraviolet]] radiation, and a reduction in the [[aragonite]] saturation of surface seawater that is connected with [[ocean acidification]].<ref>{{cite journal |author1=Meissner, K.J. |author2=Lippmann, T. |author3=Gupta, Sen |year=2012 |title=Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years |journal=Coral Reefs |volume=31 |issue=2 |pages=309–319 |doi=10.1007/s00338-011-0866-8 |bibcode=2012CorRe..31..309M |s2cid=16814102 }}</ref> Although stressed corals are more susceptible to coral diseases, it is infectious organisms that actually cause these diseases. [[Pathogen]]s so far identified include bacteria, fungi and protozoans.{{citation needed|date=November 2017}} |
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==Pathogens== |
==Pathogens== |
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* [[Black necrosing syndrome]], or Dark spots disease, probably [[fungal]].{{citation needed|date=November 2017}} |
* [[Black necrosing syndrome]], or Dark spots disease, probably [[fungal]].{{citation needed|date=November 2017}} |
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* [[Black band disease]], probably caused by an assortment of photosynthetic and non-photosynthetic bacteria. |
* [[Black band disease]], probably caused by an assortment of photosynthetic and non-photosynthetic bacteria. |
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* Brown band disease is brought about by infections caused by [[protozoa]]. It can be identified through a brown band that separates healthy portions of coral skeleton from unhealthy sections of the skeleton.<ref name="Woodley" /> |
* Brown band disease is brought about by infections caused by [[protozoa]]. It can be identified through a brown band that separates healthy portions of coral skeleton from unhealthy sections of the skeleton.<ref name="Woodley">{{cite book |author1=Woodley, Cheryl M. |url=https://books.google.com/books?id=U8gbCQAAQBAJ |title=Diseases of Coral |author2=Downs, Craig A. |author3=Bruckner, Andrew W. |author4=Porter, James W. |author5=Galloway, Sylvia B. |date=2016 |publisher=John Wiley & Sons |isbn=978-0-8138-2411-6 |pages=1–2 |author4-link=James W. Porter (ecologist)}}</ref> |
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* [[Rapid Wasting]], possibly caused by a fungus growing on areas damaged by the feeding of the [[Stoplight parrotfish]].{{citation needed|date=November 2017}} |
* [[Rapid Wasting]], possibly caused by a fungus growing on areas damaged by the feeding of the [[Stoplight parrotfish]].{{citation needed|date=November 2017}} |
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* [[White band disease]], the cause of this disease remains unknown. |
* [[White band disease]], the cause of this disease remains unknown. |
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Revision as of 18:06, 1 November 2023
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.[1][2] 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.[3] These diseases are diverse, including pathogens of bacteria, fungi, viruses, and protozoans.[1] 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.[4][5]
Stress factors
Like other organisms, stony corals and soft corals are subject to disease. This may not have been obvious in the past, but is becoming increasingly apparent in the twenty-first century. The rising ill health of corals is partially the result of the corals being subjected to increasing amounts of stress as the physical environment around them becomes less suited to their needs.[6][7] Corals live within a precise range of abiotic environmental conditions including water temperature, salinity and water quality. Variations outside the normal range of these parameters may make the corals less able to grow and reproduce successfully, and may make them more susceptible to diseases.[6] One of the major consequences that can occur with stress is the coral expelling its zooxanthellae, which are mutualistic algae that live inside coral. Corals without their symbionts become bleached, which effectively kills them since they are unable to gain the correct nutrients without their symbionts. Corals being sensitive to stress factors makes it difficult to study diseases, because the pathogen could impact any part of the coral-symbiont mutualism in the same ways that environmental factors do.[8]
Pathogens
Coral diseases mostly take the form of a narrow band of diseased tissue separating the living tissue from the exposed skeleton. The band moves across the surface of the colony at the rate of a few millimetres a day, leaving behind bare skeletal material that is rapidly colonized by algae.[9]
Many of the diseases that affect corals are known by their most obvious symptoms such as black band disease, white pox and yellow-band disease.[10] However, in many instances it has not been possible to identify the pathogens responsible for the disease and culture them in the laboratory; that the coral is sick and the tissue is necrotic is apparent, but whether the fungi or bacteria present caused the disease or merely fed on the already dying tissue is not clear. There is also a minute crab a millimetre or so wide which is often associated with diseased corals, but whether it introduces the disease or just moves in to consume the necrotic tissue is uncertain.[10] Some of the bacteria found on diseased corals are terrestrial species that are not normally considered pathogenic. Further research has shown that viruses may be involved in white plague infections, the coral small circular single-stranded DNA (ssDNA) viruses being present in association with diseased tissue. Viruses in this group are known to cause disease in some plants and animals.[11]
Distribution
Corals growing in the Caribbean Sea are particularly affected by disease, perhaps because of the limited water circulation and the density of the human population on the surrounding land masses. Disease is also present in the tropical Indo-Pacific, but it is not so widespread, perhaps because of the more dispersed locations of the reefs.[10]
Bacterial communities
The bacterial communities in coral reefs are similar overall, but for each individual coral the bacterial community can differ greatly. Coral is thought to follow the "Anna Karenina Hypothesis". This means that healthy coral will have similar bacterial communities, but diseased corals that are infected with the same disease will have different bacterial communities.[12]
Coral diseases
- Aspergillosis, caused by the fungus Aspergillus sydowii, affects Gorgonian soft corals commonly known as sea fans.
- White pox disease, caused by Serratia marcescens.
- Black necrosing syndrome, or Dark spots disease, probably fungal.[citation needed]
- Black band disease, probably caused by an assortment of photosynthetic and non-photosynthetic bacteria.
- Brown band disease is brought about by infections caused by protozoa. It can be identified through a brown band that separates healthy portions of coral skeleton from unhealthy sections of the skeleton.[13]
- Rapid Wasting, possibly caused by a fungus growing on areas damaged by the feeding of the Stoplight parrotfish.[citation needed]
- White band disease, the cause of this disease remains unknown.
- White plague, sometimes caused by the bacterium Aurantimonas coralicida.
- Skeletal eroding band, caused by the protozoan Halofolliculina corallasia.
- Yellow-band disease, possibly caused by an unidentified species of Vibrio.
References
- ^ a b Harvell, Drew; Jordán-Dahlgren, Eric; Merkel, Susan; Rosenberg, Eugene; Raymundo, Laurie; Smith, Garriet; Weil, Ernesto; Willis, Bette (2007). "Coral disease, environmental drivers, and the balance between coral and microbial associates" (PDF). Oceanography. 20: 172–195. ISSN 1042-8275.
- ^ Woodley, Cheryl M.; Downs, Craig A.; Bruckner, Andrew W.; Porter, James W.; Galloway, Sylvia B., eds. (2016). Diseases of coral. Hoboken, New Jersey: Wiley Blackwell. ISBN 978-0-8138-2411-6.
- ^ Sokolow, S (2009-11-16). "Effects of a changing climate on the dynamics of coral infectious disease: a review of the evidence". Diseases of Aquatic Organisms. 87: 5–18. doi:10.3354/dao02099. ISSN 0177-5103.
- ^ Sweet, Michael; Jones, Rachel; Bythell, John (2012-06). "Coral diseases in aquaria and in nature". Journal of the Marine Biological Association of the United Kingdom. 92 (4): 791–801. doi:10.1017/S0025315411001688. ISSN 0025-3154.
{{cite journal}}: Check date values in:|date=(help) - ^ Pollock, F. Joseph; Morris, Pamela J.; Willis, Bette L.; Bourne, David G. (2011-10-20). "The Urgent Need for Robust Coral Disease Diagnostics". PLOS Pathogens. 7 (10): e1002183. doi:10.1371/journal.ppat.1002183. ISSN 1553-7374. PMC 3197597. PMID 22028646.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link) - ^ a b Harvell, Drew; Jordán-Dahlgren, Eric; Merkel, Susan; Rosenberg, Eugene; Raymundo, Laurie; Smith, Garriet; Weil, Ernesto; Willis, Bette (2007). "Coral disease, environmental drivers, and the balance between coral and microbial associates" (PDF). Oceanography. 20: 172–195. ISSN 1042-8275.
- ^ Woodley, Cheryl M.; Downs, Craig A.; Bruckner, Andrew W.; Porter, James W.; Galloway, Sylvia B., eds. (2016). Diseases of coral. Hoboken, New Jersey: Wiley Blackwell. ISBN 978-0-8138-2411-6.
- ^ Bourne, David G.; Garren, Melissa; Work, Thierry M.; Rosenberg, Eugene; Smith, Garriet W.; Harvell, C. Drew (2009-12). "Microbial disease and the coral holobiont". Trends in Microbiology. 17 (12): 554–562. doi:10.1016/j.tim.2009.09.004.
{{cite journal}}: Check date values in:|date=(help) - ^ Spalding, Mark; Ravilious, Corinna; Green, Edmund Peter (2001). World Atlas of Coral Reefs. University of California Press. pp. 132–133. ISBN 978-0-520-23255-6.
- ^ a b c Sheppard, Charles (2014). Coral Reefs: A Very Short Introduction. Oxford University Press. pp. 106–108. ISBN 978-0-19-150523-2.
- ^ Soffer, Nitzan; Brandt, Marilyn E.; Correa, Adrienne M.S.; Smith, Tyler B.; Thurber, Rebecca Vega (2014). "Potential role of viruses in white plague coral disease". ISME Journal. 8 (2): 271–283. doi:10.1038/ismej.2013.137. PMC 3906806. PMID 23949663.
- ^ Bucher, Maite. "Health and Disease Signatures of the Coral Microbiome • iBiology". iBiology. iBiology. Retrieved 14 May 2020.
- ^ Woodley, Cheryl M.; Downs, Craig A.; Bruckner, Andrew W.; Porter, James W.; Galloway, Sylvia B. (2016). Diseases of Coral. John Wiley & Sons. pp. 1–2. ISBN 978-0-8138-2411-6.