Standardized short-term acute heat stress assays resolve historical differences in coral thermotolerance across microhabitat reef sites (CBASS vs CLASSIC)

Here we conducted a series of 18-hour short-term acute heat stress assays using CBASS (Coral Bleaching Automated Stress System) side-by-side with a 21-day long-term heat stress experiment (CLASSIC) to assess the ability of both approaches to resolve putative differences in coral thermotolerance and to approximate in situ reef temperature thresholds. Using a suite of physiological parameters (photosynthetic efficiency, coral whitening, chlorophyll a, host protein, algal symbiont counts, and algal type association), we assessed bleaching susceptibility of Stylophora pistillata colonies from the windward/exposed and leeward/protected sides of a near-shore coral reef in the central Red Sea, which had previously shown differential mortality during a natural bleaching event.