Kim B. Ritchie, J. H. Dennis, Tom McGrath and Garriet W. Smith. 1993. Bacteria Assiciated with Bleached and Nonbleached areas of Monastrea annularis. Poc. 5th Symp. Nat. Hist. Bahamas, 75-80. Reports of bleaching in corals and other organisms have been increasing in frequency over the past several years. These reports have stimulated a great deal of interest in the cause of this phenomenon, but little experimental work has been performed. This study began a systematic survey of bacteria associated with the surface of bleached and nonbleached areas of the scleractinian coral Monastrea annularis. In February 1993, a M.annularis was located in French Bay (San Salvador, Bahamas) which showed areas of bleaching. Syringe samples were taken from bleached and nonbleached areas, including surface mucus layers and polyp tissue. Samples were transferred to vials, kept on ice, and plated out on a nonselective medium. Individual bacterial isolates were then restreaked, checked for purity and inoculated onto microplates containing 95 different potential carbon sources and a water control (BIOLOG PLATES TM). The oxidation of the carbon sources produced a pattern characteristic of each isolate. These patterns were entered into a data base from which comparisons of isolates from bleached and healthy areas were made. Isolate patterns were entered into a cluster corresponding to Vibrio/Aromonas while none of the isolates from healthy areas fell into this cluster. This approach may allow the determination of pathogens involved in the cause or development of bleaching events.