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Field Guide to Western Atlantic Coral Diseases

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Types of Coral Disease and Their Identification

Black-Band Disease (BBD)

Blushing star coral, Stephanocoenia intersepta with BBD	Black-band disease gets its name from the darkly colored mat or band of microorganisms that slowly advances across the coral. Coral tissue beneath this mat is dying due to a lack of oxygen and the presence of hydrogen sulfide, and necrotic tissue is consumed by a variety of opportunistic organisms. Related pages: Differences Between BBD and white-band disease Differences Between BBD and white plague Predators and BBD Global Distribution of BBD
This disease forms a crescent-shaped or circular band of blackish material that can range from a few millimeters to several centimeters wide and may be up to 2 meters in length on large corals. BBD separates live coral tissue from white, exposed skeleton. BBD infections normally start at the edge of a colony, in a depression on a colony's surface, or at the edge of a previous injury. Once established, BBD advances 2-3 millimeters per day or more, to a maximum of 2 centimeters per day. The thickness of the band varies among individual corals, during different times of the year, and over the duration of an infection.	Mountainous star coral, Montastraea faveolata with BBD in two locations
close-up of BBD on Montastraea annularis Filaments of Beggiatoa bacteria are visible in this BBD infection.	The band is black to maroon in color due to the photosynthetic pigments (phycocyanin and phycoerythrin) of the cyanobacteria (also called blue-green algae; Phormidium corallyticum). A white dusting of filamentous (sulfide-oxidizing; Beggiatoa) bacteria is often visible. These microorganisms consist of long, unbranched filaments that are visible to the naked eye, and are intertwined to form a dense mat. This mat is loosely anchored in living tissue and is easily dislodged by water motion.
The number of corals on a reef infected with BBD at any given time fluctuates, but infections periodically occur on most reefs at low frequency, to depths of over 100 feet. In the summer and fall, particularly in clear water environments and when sea water temperatures are at their peak, more corals tend to become infected, and the rate of disease spread typically increases. BBD disappears or becomes hard to find when water temperatures decline below 22° C, and also during extended periods of low water clarity.
	When one coral is infected with BBD, other infected colonies usually occur close by, resulting in a clumped distribution of BBD. The disease is easily dislodged by water movement and divers must use care when examining corals with BBD. Watch your fins and avoid sudden movement near affected corals as this may cause water turbulence. The disease can spread from one colony to neighboring corals, and also can spread from one lobe to another on the same colony of star coral (M. annularis).
Black-band disease also occurs on sea fans and branching gorgonians.

Black-band disease can be found on the following species of coral:

Agaricia agaricites, Colpophyllia natans, Dichocoenia stokesii, Diploria clivosa, Diploria labyrinthiformis, Diploria strigosa, Favia fragum, Manicina areolata, Meandrina meandrites, Montastraea annularis, Montastraea cavernosa, Montastraea faveolata, Montastraea franksi, Mycetophyllia ferox, Mycetophyllia lamarkiana, Siderastrea radians, Solenastrea hyades, Stephanocoenia intersepta, Siderastrea siderea.