Climate change‐amplified temperature anomalies pose an imminent threat to coral reef ecosystems. While much focus has been placed on the effects of heat stress on scleractinian corals—including bleaching, mortality, and loss of reef structural complexity—and many studies have documented changes to reef fish communities arising indirectly from shifts in benthic composition, the direct impacts of heat stress on reef fish are much less well understood. Here, we quantify the direct and indirect effects of heat stress on reef fishes, using underwater visual censuses of coral reef fish communities conducted before, during, and after the 2015–2016 El Niño‐induced global coral bleaching event. Surveys took place at the epicenter of this event, at 16 sites on Kiritimati (Republic of Kiribati; central equatorial Pacific) spanning across a gradient of local human disturbance. We expected that heat stress would have both direct and indirect negative effects on the reef fish community, with direct effects resulting from physiological stress during the event and indirect effects manifesting afterward as a consequence of coral mortality, and that the ability of fish communities to recover following the heat stress would depend on levels of local human disturbance. We found that total reef fish biomass and abundance declined by >50% during heat stress, likely as a result of vertical migration of fish to cooler waters. One year after the cessation of heat stress, however, total biomass, abundance, and species richness had recovered to, or even exceeded, pre‐heat stress levels. However, the biomass of corallivores declined by over 70% following severe coral loss, and reefs exposed to higher levels of local human disturbance showed impaired recovery following the heat stress. These findings enhance understanding of the projected impacts of climate change‐associated marine heatwaves on reef fishes, and highlight the interacting effects of local and global stressors on this vital component of coral reef ecosystems.

中文翻译：

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气候变化放大的脉冲热应力事件对珊瑚礁鱼类群落的直接和间接影响。

气候变化加剧的温度异常对珊瑚礁生态系统构成了迫在眉睫的威胁。尽管人们已经将许多重点放在了热应激对巩膜珊瑚的影响上，包括漂白，死亡和珊瑚礁结构复杂性的丧失，但许多研究表明，底栖动物组成的变化间接引起了珊瑚礁鱼类群落的变化，这是珊瑚礁直接影响的结果。对珊瑚鱼的热应激了解得很少。在此，我们使用2015-2016年厄尔尼诺现象引发的全球珊瑚白化事件之前，之中和之后进行的水下珊瑚礁视觉普查，量化了热应激对珊瑚礁鱼类的直接和间接影响。在该事件的震中，在基里蒂马蒂（基里巴斯共和国；横跨赤道中太平洋地区）。我们预计，热应激将对珊瑚礁鱼类群落产生直接和间接的负面影响，事件期间由于生理压力而产生的直接影响以及随后由于珊瑚死亡而表现出的间接影响，以及鱼类群落恢复的能力跟随热应激将取决于当地人为干扰的程度。我们发现，在热应激期间，珊瑚礁鱼的总生物量和丰度下降了50％以上，这可能是由于鱼向较冷水域垂直迁移所致。但是，在停止热应激一年后，总生物量，丰度和物种丰富度恢复到甚至超过了热应激前的水平。然而，在严重的珊瑚流失之后，珊瑚虫的生物量下降了70％以上，暴露于较高水平的当地人为干扰的珊瑚礁在热应激后恢复能力受损。这些发现加深了对与气候变化相关的海洋热浪对珊瑚礁鱼类的预计影响的理解，并强调了本地和全球压力源对珊瑚礁生态系统这一重要组成部分的相互作用。