Coral bleaching in extreme environments: speciesspecific thermal tolerance limits

Increasing seawater temperatures are being measured worldwide, causing coral bleaching events during which the symbiosis between the coral host and its symbiotic zooxanthellae is disrupted, and a global decline in reef corals. In the Arabian Gulf where water temperatures are naturally extreme with summer maxima at 35°C and above and winter minima at 18°C and below, seawater temperature anomalies are repeatedly recorded in the summer. While Arabian Gulf corals have naturally evolved to survive at temperatures that would cause bleaching and mortality to most corals elsewhere, an increasing number of mortality events have been recorded in the Gulf (Qatar, Saudi Arabia, and the UAE) in the last decades, resulting in a substantial loss of biodiversity and coral cover, mostly in inshore environments. Efforts are being deployed locally to conserve remaining habitats and attempt the restoration of lost habitats, but to be successful, efforts need to incorporate regional species-specific traits such as the suscept...