Identifying the culprits of coral disease

By Valerie Perini

The global decline in reef-building corals is in part due to the rise of bacterial disease impacting these important tropical foundation species. However, researchers have only a limited understanding of the bacteria that cause these devastating coral diseases. In an effort to increase this understanding, MSC graduate student Sarah Gignoux-Wolfsohn and Associate Professor Steve Vollmer recently conducted a study characterizing disease causing bacteria on the ubiquitous Caribbean staghorn coral.

In the study, published in the journal PLOS ONE, the researchers used Illumina 16S rRNA gene sequencing to characterize the bacterial communities on both healthy and diseased staghorn coral (Acropora cervicornis), collected at four Caribbean field sites during two different years. The researchers also conducted a laboratory component of the experiment, to account for inherent variation associated with field experimentation, by exposing coral in tanks to fluids collected from healthy and diseased corals.

Results of the gene sequencing indicated marked differences in the bacterial communities of healthy and diseased corals, and researchers were able to identify differences in the abundances of individual operational taxonomic units (OTUs), which serves as a proxy for identifying different types of bacteria. The study identified 16 healthy, and 106 disease associated OTUs, some of which could be candidates for the pathogen causing one of the most common coral diseases, white band disease.

This work brings coral researchers one step closer to understanding the causes and consequences of bacterial disease in corals, which will aid in future efforts to conserve and manage these essential reef-building animals.