Predicting Coral Bleaching: Remote Sensing vs. In Situ Measurements of Sea Surface Temperatures

Here we present a case study where we compare the skill of predicting coral bleaching using two sources of Sea Surface Temperature (SST) data. Remotely sensed microwave (TMI) data and in situ observations of SST are used to calculate Degree Heating Weeks, a NOAA technique to predict thermal stress on coral reefs. The in situ observations have been made over a period of 1993-2007 at the Le Port, Reunion. We calculate DHW and compare it to a database of reef observations at Reunion, enabling us to assess skill for the predictive method using both sources of SST data. Quantitative accuracy assessment, using well established methods and skill scores often used in meteorology and medical sciences (Peirce Skill Score, Hit Rate and False Alarm Rate), enable objective optimization of the predictive technique for each SST source. The differences in skill expressed in Hit Rate and False Alarm Rate have implications for decision making concerning reef management and conservation techniques.