OXYGEN AND SULFIDE DYNAMICS IN A HORIZONTALLY MIGRATING CYANOBACTERIAL MAT - BLACK BAND DISEASE OF CORALS

Black band disease is caused by a horizontally migrating microbial con sortium which overgrows and kills reef-building corals in many areas o f the world. The cyanobacterium Phormidium corallyticum, the sulfide-o xidizing bacterium Beggiatoa sp., fungi, and sulfate-reducing bacteria dominate the consortium, which is generally several mm to 1 cm in wid th and ca. 1 mm in thickness. Microelectrode measurements revealed pho tosynthetically produced O-2-supersaturation in upper layers during da y, although conditions at the band-coral interface were consistently a noxic and, at night, sulfide-rich. Diel distributions of oxygen and su lfide resembled those from cyanobacterial mats in sulfur springs, inte rtidal mats and hypersaline lagoons.