Long-Term Detection of Coral Reef Thermal Stress Events Using Daily Satellite Data in the Red Sea

Coral reefs are facing many challenges globally, especially adaptation to global warming. Investigating distributional changes of thermal stress has become an extensive research topic, aiming to help stakeholders adapt to future climate-driven changes. The relationship of time series analysis between sea surface temperature and coral reef bleaching increases our understanding of the coral reef health at the Egyptian Red Sea. Fourteen years of a high-resolution (1 km) daily satellite-derived (MODIS-A) sea surface temperature (SST) are used to analyse the thermal stress, degree of heating week (DHW) and annual patterns of SST variability in the Egyptian Red Sea. Long-term daily data were processed using MATLAB code script to calculate the average, climatology, anomalies, thermal stress, maximum, minimum and DHW. The total mean proportion of dead and bleached corals gradually increased from 2013 to 2015 for all studied cities. The present paper obtained that the three years of the total observed bleaching was positively correlated with sea surface temperature at all studied cities (r = 0.71, 0.96, 0.89 and 0.88) at Ras Ghareb, Hurghada, Qusier and Marsa Alam respectively. The accumulated DHW resulted that there are four thermal stress events during 14 years in 2003, 2007, 2010 and 2012. The annual analysis shows a general upward sea surface temperature trend in the study area.