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Mid-range prediction of coral bleaching: A molecular biomarker approach.
Fauth, John1, Downs, Craig2, Halas, John3, Dustan, Phillip1, Woodley, Cheryl4, 1 2 3 4
ABSTRACT- One challenge facing ecological forecasting is making accurate mid-range predictions of changes in ecosystem health. Accurate predictions made months in advance could allow resource managers time to minimize or ameliorate stressors that threaten ecosystem structure, function and integrity. We developed a molecular biomarker system to assess the physiological status of corals, assaying specific parameters of cellular physiology indicative of health status. This technology is particularly relevant for corals because multiple environmental stressors (i.e., heat, ultraviolet light, eutrophication) contribute to coral bleaching, one etiology for coral mortality worldwide. In field samples of boulder corals (Montastraea annularis) from the Florida Keys, we observed a strong correlation between molecular biomarker levels and bleaching of individual coral colonies. Using logistic regression, we identified molecular biomarkers capable of predicting the onset of coral bleaching 3-6 months before symptoms became apparent. Biomarkers useful in forecasting included glutathione, which is an antioxidant; lipid peroxides, which indicate functional lipid levels and membrane integrity; and chloroplast small heat shock proteins (chlpsHsp), which protect photosystem II activity during oxidative stress. The relationships we observed between water depth, chlpsHsp levels and bleaching strongly suggest that the inability of deep-water corals to accumulate enough chlpsHsp to protect against photoinhibitory production of oxidative stress is a major cause of bleaching. Molecular biomarkers provide useful tools for ecological forecasting because the parameters they assay directly reflect the condition of vital cellular and physiological processes.
KEY WORDS: ecological forecasting, coral bleaching, ecosystem health assessment, molecular biomarkers