Diagnostic tools 2011


Since the occurrence of mass coral bleaching episodes on the Great Barrier Reef, first observed in 1998, the AIMS Long-term Monitoring Team has documented low but significant levels of coral disease that peak following unusually warm summers. While overall disease levels are not yet a matter of concern for the GBR, AIMS' scientists are aware of the much greater role attributed to disease in causing the relatively rapid demise of coral reefs in parts of the Caribbean.

Although disease outbreaks on the GBR are a minor cause of coral cover lost from the whole system, the ironic twist is that their impact is greatest in local areas where coral densities remain high. This effect comes most likely through water-borne chemical signalling among the microbial associates of stressed corals, which include pathogenic bacteria that can respond with explosive growth through their own chemically-mediated process called "quorum sensing".

In 2008, Dr Bryan Wilson was awarded a three-year fellowship from Queensland's Smart State Fund to develop a rapid diagnostic tool for detecting the abundance of pathogenic bacteria causing the most common coral diseases.  Given the international interest in this problem (see above reference to Caribbean reefs), this project was co-sponsored by AIMS, the Hawaiian Institute of Marine Biology (HIMB), and other partners.

Based on previous work, Vibrio coralliilyticus was selected as a model organism. By the end of the Fellowship, two methods have been validated as alternative ways to detect the abundance of this pathogen. As is often the case in research, however, the final stage of building the diagnostic tool for coral disease has shown that the same technology may have equal applicability to the detection of a closely-related bacterial pathogen of shellfish causing commercial losses in the aquaculture industry. This application will also be pursued in future research.