The Role of Coral-Associated Bacterial Communities in Australian Subtropical White Syndrome of Turbinaria mesenterina

Abstract

Australian Subtropical White Syndrome (ASWS) is an infectious, temperature dependent disease of the subtropical coral Turbinaria mesenterina involving a hitherto unknown transmissible causative agent. This report describes significant changes in the coral associated bacterial community as the disease progresses from the apparently healthy tissue of ASWS affected coral colonies, to areas of the colony affected by ASWS lesions, to the dead coral skeleton exposed by ASWS. In an effort to better understand the potential roles of bacteria in the formation of disease lesions, the effect of antibacterials on the rate of lesion progression was tested, and both culture based and culture independent techniques were used to investigate the bacterial communities associated with colonies of T. mesenterina. Culture-independent analysis was performed using the Oligonucleotide Fingerprinting of Ribosomal Genes (OFRG) technique, which allowed a library of 8094 cloned bacterial 16S ribosomal genes to be analysed. Interestingly, the bacterial communities associated with both healthy and disease affected corals were very diverse and ASWS associated communities were not characterized by a single dominant organism. Treatment with antibacterials had a significant effect on the rate of progress of disease lesions (p = 0.006), suggesting that bacteria may play direct roles as the causative agents of ASWS. A number of potential aetiological agents of ASWS were identified in both the culture-based and culture-independent studies. In the culture-independent study an Alphaproteobacterium closely related to Roseovarius crassostreae, the apparent aetiological agent of juvenile oyster disease, was found to be significantly associated with disease lesions. In the culture-based study Vibrio harveyi was consistently associated with ASWS affected coral colonies and was not isolated from any healthy colonies. The differing results of the culture based and culture-independent studies highlight the importance of using both approaches in the investigation of microbial communities.

Bacterial Communities Associated with Porites White Patch Syndrome (PWPS) on Three Western Indian Ocean (WIO) Coral Reefs

“…Among them, ribotypes similar to Pseudoalteromonas spp., Paracoccus yeei and Amphritea balenae have been previously identified in seawater [32], soil [33] and sediment [34] respectively, suggesting that these bacteria were present in the environment and opportunistically became resident in the coral mucus or associated with the healthy coral microbiota. Similar variations in the bacterial communities have been reported in several coral species affected by BBD [35], WPD [17], WBD in the Caribbean [14] and other WS in Australia and American Samoa [15], [20], [36]. The bacterial diversity found in PWPS was higher than in HT at all three localities.…”

Bacterial diseases in marine bivalves

“…JOD was then renamed Roseovarius Oyster Disease (ROD) to avoid confusion with other diseases of juvenile oysters (Maloy et al, 2007b). To date, all isolates of R. crassostreae have originated from affected oysters but molecular surveys have also indicated a possible role for this species in various diseases of corals (Cooney et al, 2002;Pantos and Bythell, 2006;Godwin et al, 2012).…”

Crustose coralline algal species host distinct bacterial assemblages on their surfaces

“…in the family Rhodobacteraceae was found in higher abundances on P. pachydermum (1.85 ± 4.14%) compared with other CCA species. Both V. harveyi and members of the Rhodobacteraceae have been associated with invertebrate diseases including coral disease (Godwin et al, 2012;Roder et al, 2014).…”