Determination of Phenotypic Responses to Heat Stress Experiments in Corals from the Great Barrier Reef

Erin Bowman

Climate change and increasing sea surface temperature have made it imperative that scientists advance their understanding of how corals respond to thermal bleaching events. Many methods to evaluate coral stress responses are invasive and do harm to reefs, while there are limited non-invasive options. Hyperspectral imagery for assessment of fluorescent proteins which have photoprotective and antioxidant properties may be a useful non-invasive method to detect coral thermal stress but remains largely untested against existing approaches. Here, hyperspectral imaging data (fluorescent protein and chlorophyll reflectance) was compared to pulse amplitude modulation (PAM) fluorometry data (symbiont photosynthetic efficiency) in order to discern if it is an effective method for evaluating coral health. High temperatures elicited a decrease in photosynthetic efficiency and an increase in fluorescent protein reflectance, while chlorophyll reflectance was unaffected. Variation in these traits among coral samples indicates that some genotypes and species are able to better protect themselves in stressful environments than others. This outcome suggests that hyperspectral imagery can reveal fine-scale adaptations among coral species and individuals without destruction of the holobiont. In future studies, hyperspectral imagery can be combined with other evaluation methods to obtain greater knowledge regarding coral thermal stress responses.