Coralline Lethal Disease

A second disease of coralline algae was recognized by Tom Goreau in the Caribbean in 1996. It lacks the characteristic orange color of CLOD, but is lethal, nonetheless. It is known as coralline lethal disease (CLD).

Coralline lethal disease. Photo by A. Bruckner.
Appearance	The bright orange band is not present, but the pink algal tissue disappears along a thin white margin (1-2 millimeters wide) and filamentous algae grows over the bare coralline thallus. The white margin is visible in the lower center of the photo above as a diagonal line rising from left to right.
Close-up of Coralline lethal disease. Photo by A. Bruckner.
Appearance - continued	Note the thin white margin (1-2 millimeters wide) in the close-up photo above. Three areas of coralline lethal disease are apparent as concentric white circles surrounding patches of green filamentous algae that have colonized the dead portion of the coralline algae.
Distribution	Coralline lethal disease was observed in the Caribbean, beginning in 1996, with more recent observations in the Indian Ocean and off the Philippines.
Impact	The recent appearance of these diseases in the Indo-Pacific and tropical western Atlantic could potentially affect the structure and function of many reef sites, since dead corallines, like dead corals, no longer contribute to productivity and carbonate accretion processes and filamentous and fleshy algae overgrow the bare skeletons, inhibiting the settlement and growth of reef-building corals.