Remarkably high and consistent tolerance of a Red Sea coral to acute and chronic thermal stress exposures

Global warming is resulting in unprecedented levels of coral mortality due to mass bleaching events and, more recently, marine heatwaves, where rapid increases seawater temperature cause within days. Here, we compare the response a ubiquitous scleractinian coral, Stylophora pistillata, from northern Red Sea acute (7 h) and chronic (7–11 d) thermal stress that include treatments 27°C (i.e., local maximum monthly mean), 29.5°C, 32°C, 34.5°C, assess recovery corals following exposure. Overall, S. pistillata exhibited remarkably similar responses stress, responding primarily treatment rather than duration or heating rate. Additionally, displayed an exceptionally high tolerance, maintaining their physiological performance suffering little no loss algal symbionts chlorophyll up before host suffered tissue necrosis at 34.5°C. While there was some variability metrics, photosynthetic efficiency measurements quantum yield Fv/Fm) accurately reflected overall patterns, with these used produce Fv/Fm effective dose (ED50) metric as proxy for tolerance corals. This approach produced ED50 values experiments (34.47°C vs. 33.81°C), highlighting potential assays systematic standardized quantitively upper limits reef-building using portable experimental system.