Our study reveals a hitherto overlooked ecological threat of climate change. Studies of warming events in the ocean have typically focused on the events’ maximum temperature and duration as the cause of devastating disturbances in coral reefs, kelp forests, and rocky shores. In this study, however, we found that the rate of onset (R_onset), rather than the peak, was the likely trigger of mass mortality of coral reef fishes in the Red Sea. Following a steep rise in water temperature (4.2 °C in 2.5 d), thermally stressed fish belonging to dozens of species became fatally infected by Streptococcus iniae. Piscivores and benthivores were disproportionately impacted whereas zooplanktivores were spared. Mortality rates peaked 2 wk later, coinciding with a second warming event with extreme R_onset. The epizootic lasted ∼2 mo, extending beyond the warming events through the consumption of pathogen-laden carcasses by uninfected fish. The warming was widespread, with an evident decline in wind speed, barometric pressure, and latent heat flux. A reassessment of past reports suggests that steep R_onset was also the probable trigger of mass mortalities of wild fish elsewhere. If the ongoing increase in the frequency and intensity of marine heat waves is associated with a corresponding increase in the frequency of extreme R_onset, calamities inflicted on coral reefs by the warming oceans may extend far beyond coral bleaching.

我们的研究揭示了迄今为止被忽视的气候变化生态威胁。海洋变暖事件的研究通常集中在事件的最高温度和持续时间，这是造成珊瑚礁，海带森林和多岩石的海岸破坏性扰动的原因。但是，在这项研究中，我们发现红海珊瑚礁鱼类的大量死亡可能是由_发病率（R_发病率）而不是峰值引起的。在水温急剧上升（2.5 d内为4.2°C）之后，属于数十种鱼类的热应激鱼被链球菌致命感染。食肉动物和底栖动物受到的影响不成比例，而浮游动物却幸免了。死亡率在2周后达到峰值，与第二次极端R变暖事件相吻合_起病。流行病持续了约2个月，直至变暖事件结束为止，未感染鱼食用了富含病原体的car体。气候变暖普遍存在，风速，大气压力和潜热通量明显下降。对过去报道的重新评估表明，陡峭的R_爆发也是其他地方野生鱼类大量死亡的诱因。如果海洋热浪的频率和强度的持续增加与极端R_发作频率的相应增加有关，那么变暖的海洋对珊瑚礁造成的灾难可能会远远超出珊瑚白化的范围。