Disease

Coral Disease

Why Study Coral Diseases?

Diseases have taken a major toll on the coral population in reefs across the globe. The impact has be exceptionally significant in the Caribbean in which up to 80% of the coral has been decimated. One of the major problems of coral diseases is that there is a variety of disease and within each there are multiple types. Furthermore to complicate the situation, many of the causes of the diseases are unknown, whcih makes it difficult to treat.

Main Coral Diseases in the Caribbean

Dark Spots Disease (in depth)

• Relevant in the Florida Keys and wider Caribbean
  
• Affected areas are dark purple, gray or brown
• circular or irregular in shape scattered on surface of a colony or at colony's margin
• discolored area increases in size and radiates outward as affected area dies
• Darkened polyps are often depressed and appear smaller in size
• Popular on S. siderea (massive starlet coral), blushing star coral, and M. annularis

Black Band Disease

• Characterized by blackish concentric/crescent-shaped band (given by photosynthetic pigment of the dominant cyanobacteria)
• Consumes live coral tissue as it passes over colony surface
• Caused primarily by cyanobacteria along with sulfide-oxidizing and sulfur-reducing bacteria
• Most commonly affects massive reef-building corals all over the world
• Leaves behind bleached coral

Red band disease

• Narrow bands of filamentous cyanobacteria
• First type, RBD-1, closely resembles BBD except that bands are maroon in color
• Second type, RBD-2, has cyanobacterial filaments spread like a net over colony's surface
• Microbial mat is easily dislodged from surface of coral tissue
• Affects massive and plating stony corals, and also sea fans throughout the wider Caribbean
• Leaves behind bleached coral

White Band Disease

• Extensive occurrence in the Caribbean
• Effects Elkhorn and Staghorn Coral
• Tissue Peels off the coral starting at the base causing thick white bands of bleached coral
• Presumed bacterial infection that affects the Genus Acropora
  • Two types of the disease
• Pathogen unknown but leaves behind brittle coral skeleton
• One of the only diseases known to cause major changes in structural composition of reefs
• After tissue peels away skeleton is weakened by bioerosion

White Pox Disease

• Occurs in the Florida Keys and the Caribbean
• Affects Elkhorn coral
• Causes irregular lesions that leave white patches on coral
• Caused by the pathogen Serratia marcescens
  • Human and animal pathogen
  • Very contagious pathogen that easily spreads to other corals
• Once lesions form algae takes over

Yellow Blotch Disease

• Occurs in the Florida Keys and Caribbean
• Sections of corals become yellowed and translucent
• Cause unknown
• Disease spreads outward and the tissue in the center dies
• Mostly affects large boulder star corals
• Tissue left behind the band are usually covered in coralline algae

Implications of Diseases in Reefs

Coral reefs are an important factor for communities, especially along the costal regions. Reefs are important for economies since they bring in money through tourism and the fishing industry. The weakening reef system may pose a threat to the countries that rely on this factor as a major component of their economy. Diseased reefs do not have the same tourist draw or the fishing production as a healthy reef. Furthermore, reefs provide a barrier to protect the inland from large waves and surges. The event of coral diseases will have major negative implications. Therefore, more work and research should be focused on the causes in order to prevent further degradation of the reef ecosystem.

References
“Major Reef-building Coral Diseases.” CoRIS - Coral Reef Information System. NOAA, 01-17-13. Web. 2-26-13. <http://coris.noaa.gov/about/diseases/#red band>.
Gochfield, Deborah, Julie Olson, and Marc Slattery. “Colony Versus Population Variation in Susceptibility and Resistance to Dark Spot Syndrome in the Caribbean Coral Siderastrea Siderea.” Diseases of Aquatic Organisms 69 (2006): 53–65. Inter-Research. Web. 02-26-13. <http://www.int-res.com/abstracts/dao/v69/n1/>.
Gil-Agudelo, D.L. and J. Garzón-Ferreira 2001. Spatial and seasonal variation of dark spots disease in coral communities of the Santa Marta area (Columbian Caribbean). Bull Mar. Sci. 69:619-630
Green, E. and A. W. Bruckner. 2000. The significance of coral disease epizootiology for coral reef conservation. Biological Conservation 96:347-361.
Aronson, R. B., Precht, W. F. (2001) “White-band disease and the changing face of Caribbean coral reefs.” Hydrobiologia 460: 25-38.
Kellogg, C. A. “Montastraea cavernosa.” Photo. microbiology.usgs.gov 26 Feb. 2013. < http://microbiology.usgs.gov/image_gallery_plants_animals_montastraea_cavernosa.html>.
“White pox disease in coral caused by human pathogen” (2001). Retrieved 27 Feb. 2013 for < http://www.macroevolution.net/white-pox.html>.
“Coral Diseases” Reef Research Center. Retrieved 26 Feb. 2013 from <http://www.reef.crc.org.au/discover/coralreefs/Coraldisease.htm>
“Socioeconomic Impacts” Coral Reefs. Retrieved 26 Feb. 2013 from <http://www.reefresilience.org/Toolkit_Coral/C2c2_Socioecon.html>

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