Ectotherm's vulnerability to climate change is predicted to increase with temperature variation. Still, translating laboratory observations of organisms’ heat-stress responses to the natural fluctuating environment remains challenging. In this study, we used an integrative framework combining insights from the Thermal Death Time (TDT) curves and physiological reaction norms, to precisely capture Pinctada margaritifera’s thermal performance and tolerance landsape. We then applied this integrative model to predict individuals’ cummulative heat injury as a function of actual temperature conditions documented at five contrasting islands across French Polynesia. Substantial injury was predicted for spats (ranging from 30.24 to 29.62%) when exposed to eight consecutive extreme low tide events in Nuku Hiva. Overall, this study highlights the potential of this framework to effectively quantify the impacts of extreme events, such as marine heatwaves, and to guide resource management initiatives.