Transmission of Desulfovibrio salexigens DSM2638 bacteria in Pachyseris involuta-infection rate and changes in coral morphology at different temperatures

Desulfovibrio salexigens is one of the bacteria that infect corals with black band disease (BBD). These bacteria develop fast and cause damage to corals. Therefore, there is a monitor disease transmissinon, especially BBD, in healthy corals to determine the extent to which pathogens can infect coral tissue and the impact of these bacteria on infected coral populations. This study was conducted at the Marine Station Laboratory on Barrang Lompo Island, South Sulawesi, Indonesia. Bacteria were cultured in the Laboratory of Microbiology, Faculty of Medicine, Hasanuddin University. Corals were acclimatised in controlled containers, followed by transmission tests using aquaria (24 units, 45cm×30 cm ×30 cm) filled with 15 litres of sterile seawater. A multifactorial approach was used with treatments comprising different incubation temperature (29°C and 31°C) and different bacterial concentration in the maintenance media (10 2 , 10 4 , and 10 6 UNIT), as well as the interaction between the effects of temperature and bacterial concentration. Trial parameters were observed every day at intervals of 5 hours. Changes in the appearance diameter of corals infected with pathogenic bacteria were analysed descriptively using underwater photography (Nikon Collfix P7100 camera) and the corals were measured with callipers (precision 0.1 mm). The study concluded that the infection rate of the bacterium D. salexigens strain DSM 2638 in Pachyseris involuta was higher at 31°C-29°C. There was no interaction between the effects of temperature and bacterial concentration on the infection rate of infected coral fragments. Bacterial attack was more severe on Pachyseris involuta fragments maintained at 31°C than at 29°C.