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CORAL DISEASES
Black Band Disease
courtesy Paige Gill, Florida Keys National Marine Sanctuary
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Tolerating a very narrow range of environmental conditions including temperature, salinity, and solar radiation, reefs are very sensitive to damage from environmental changes. Corals, in particular, are susceptible to a number of diseases including black band disease, white band disease, and coral bleaching.
Black Band Disease
- Symptoms:
- Black band moving across the surface of coral colonies, leaving behind exposed white skeleton
- Entire colonies may be killed within months
- Cause:
- Blackband disease is primarily caused by a bacteria called Phormidium corallyticum
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Black band disease was first described in the early 1970s as a black band moving on the surface of star corals (Monstastrea spp.) and brain corals (Diploria spp.). It destroys live tissue as it moves over the surface of the colonies, leaving behind bare white skeleton. This disease may kill entire colonies within a matter of a few months, however tissue loss from a colony can be only partial with recovery after the black band disappears. This black band consists primarily of the filamentous cyanobacterium Phormidium corallyticum along with other microorganisms. Research has shown that the death of coral tissue is caused by lack of oxygen as well as exposure to hydrogen sulfide in the tissue adjacent to this black bacterial band.
Brain Coral Infected by Blackband Disease
courtesy U.S. Geological Survey
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Black band disease occurs when corals are stressed by environmental factors including sedimentation, nutrient levels, pollution, and high water temperatures. These stressors primarily exist during the summer months in the Florida Keys. Black band disease has been observed throughout the world's reef systems with recent outbreaks in the Caribbean and the Florida Keys.
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