A Novel Molecular Biomarker System to Assess the Physiological Status of Corals

Woodley, C; Downs, C; Fauth, J; Mueller, E; Halas, J; Bemiss, J; Ben-Haim, Y; Rosenberg, E

We developed a novel molecular biomarker system that assesses the physiological status of corals by assaying specific parameters of cellular physiology indicative of a non-stressed or stressed condition. This technology is known as the Downs Molecular Biomarker System™ (DMBS). It is particularly relevant for corals because multiple environmental stressors (e.g., heat stress, uv, cold stress, pathogens) may contribute to coral bleaching, one etiology for coral mortality worldwide. In laboratory studies, the DMBS distinguished the separate and combined effects of heat and light on a scleractinian coral (Montastraea faveolata) and its symbiotic dinoflagellate (zooxanthellae) and provided strong evidence supporting the hypothesis that oxidative stress plays a central role in coral bleaching. In field samples, colonies of Montastraea annularis in the Florida Keys showed a strong correlation between DMBS parameters of oxidative stress and bleaching. We also used this new biotechnology to characterize the pathology of coral bleaching by assessing cellular physiological parameters in explants of Oculina varicosa exhibiting bacteria-induced bleaching. Our data suggest that bacteria-induced coral bleaching may involve non-oxidative stress mechanisms. Collectively, our data showed that the DMBS can (1) diagnose whether corals were physiologically stressed, (2) can potentially discriminate between multiple mechanisms involved in coral bleaching, (3) predict the occurrence of coral bleaching at least 3-6 months before visual indications of a bleaching event, and (4) provide evidence that the chloroplast small heat-shock protein is a significant adaptation against coral bleaching.