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Abstract. The aim of this study was to isolate black band disease (BBD) samples from hard coral (Pachyseris speciosa) and to identify the main pathogenic bacteria stimulating BBD. The research was conducted from October 2015 to March 2016. Samples (fragments of diseased corals) were collected from Pulau Barrang Lompo, Pulau Badi, Pulau Bonetambung, Pulau Sarappo, and Pulau Kapoposang, Spermonde Archipelago, South Sulawesi Province. Isolates of BBD bacteria taken from these diseased samples were cultured in the Microbiology Laboratory, Faculty of Medicine, Hasanuddin University; histological analysis of diseased and healthy corals was conducted in the Pathology Laboratory, Maros Veterinary Centre, and BBD bacterial pathogenicity was tested on healthy corals at the Barrang Lompo Island Marine Station Hatchery, Faculty of Fisheries and Marine Sciences, Hasanuddin University. The bacterial density in infected coral tissue reached 109 CFU mL-1. The pathogenicity test found that the time before BBD symptoms appeared was different for each bacterium tested. BBD symptoms appeared most rapidly after infection with Desulfovibrio salexigens DSM 2638 (7 hours), followed by Flavobacterium columnare FK 401 (10 hours), Bacillus farraginis R-8039 (22 hours), and Shewanella piezotolerans WP3 (27 hours). Histology showed differences between healthy and infected coral tissue; the epidermis and gastrodermis were clearly visible in healthy corals but these structures were no longer well defined in corals infected with BBD.
Key Words: Flavobacterium columnare, Bacillus farraginis, Pachyseris speciosa, black band disease, bacterial pathogenicity.
Introduction. Coral disease is considered a severe threat to coral reefs all over the world (Sutherland et al 2004; Woodley et al 2015; Precht et al 2016) and occurrences have been reported widely in recent decades (Harvell et al 1999; Green & Bruckner 2000; Harvell et al 2002; Rosenberg & Ben-Haim 2002; Sutherland et al 2004; Raymundo et al 2005; Jones et al 2012; Miller & Richardson 2014; Johan et al 2015; Ponti et al 2016), including in the Spermonde Archipelago, in South Sulawesi, Indonesia (Muller et al 2012). Some coral reefs have already been severely damaged by disease, and the prevalence of coral disease is predicted to increase due to direct and indirect anthropogenic impacts (Jones et al 2012; Miller & Richardson 2014; Thurber et al 2014; Woodley et al 2015; McDevitt-Irwin et al 2017; Ziegler et al 2017; Wang...