Lower marine fungus associated with black line disease in star corals (Monastrea annularis, E. & S.)

A disease of corals called "black line" has become widespread in the Caribbean reefs. Although its etiology has not been determined, a lower marine fungus was found closely associated with the disease. Corals of the species Montastrea annularis (star coral) were collected from scattered areas of the Venezuelan reefs. Histological examinations of black line-diseased corals showed this unidentified fungus in and nearby all of the diseased tissue. The branched fungal hyphae lacked septa and ranged in size from 5 to 10 µm long and from 2.5 to 3.0 µm wide. No hyphae were found in black line disease-free areas. No fungi have been detected previously in soft coral tissue. The study of this naturally occurring infection could yield important information concerning pathological processes in corals.