Coral reefs are threatened worldwide by global climate change, manifested in anthropogenic ocean warming and acidification. Despite the importance of coral sexual reproduction for the continuity of coral reefs, our understanding of the extent of the impact of climate change on coral sexual reproduction, particularly on coral reproductive phenology and early life stages, is limited. Here, we experimentally examined the effects of predicted end-of-the-century seawater conditions on the sexual reproduction and photosynthetic capacity of a Red-Sea zooxanthellate octocoral, Rhytisma fulvum. Sexually mature colonies were exposed to ambient temperature and pH conditions and to Representative Concentration Pathway (RCP) conditions (4.5 and 8.5), five weeks prior to their expected surface-brooding event. The reproductive phenology of the colonies under the simulated seawater conditions was compared to that on the natural reef. In addition, subsequent planulae development and their metamorphosis into primary polyps under the same RCP conditions as their parent colonies were monitored in a running seawater system. The results reveal that both RCP conditions led to a change in the timing of onset of the surface-brooding event and its synchronicity. In contrast, the surface-brooding event under ambient conditions co-occurred with that of the in-situ reef colonies and maintained its synchrony. Similarly, planula survival and polyp metamorphosis rate were significantly reduced under both RCP conditions compared to propagules reared under ambient conditions. In addition, the photosynthetic capacity of the parent colonies under both RCPs showed a reduction relative to that under the ambient conditions in the experiment, suggesting a reduction in carbon fixation during the late stages of gametogenesis. While our findings indicate that octocoral reproductive phenology is affected by environmental changes, further work is required in order to elucidate the long-term implications for the R. fulvum population in the northern Red Sea.

全球性的气候变化正在全球范围内威胁着珊瑚礁，这表现在人为的海洋变暖和酸化作用中。尽管珊瑚有性繁殖对于珊瑚礁的连续性非常重要，但我们对气候变化对珊瑚有性繁殖，特别是对珊瑚生殖物候和生命早期的影响程度的了解有限。在这里，我们实验性地研究了预测的世纪末海水状况对红海黄附子八面体黄腐霉的有性繁殖和光合能力的影响。性成熟的菌落在预期的表面孵化事件发生前五周暴露于环境温度和pH条件以及代表性浓度途径（RCP）条件（4.5和8.5）。将模拟海水条件下菌落的繁殖物候与天然礁石上的繁殖物候进行了比较。此外，在一个运行的海水系统中，在与亲代相同的RCP条件下，监测了随后的扁平疣发育及其变态为初级息肉。结果表明，两种RCP条件均导致表面孵化事件的发生时间及其同步性发生变化。与此相反，在环境条件下的表面育雏事件共发生与所述的原位礁殖民地并保持其同步性。同样，与在环境条件下饲养的繁殖体相比，在两种RCP条件下，平板存活率和息肉变态率均显着降低。另外，相对于实验中的环境条件，两个RCPs下亲本菌落的光合能力均显示出降低，这表明配子形成后期的碳固定作用降低。虽然我们的研究结果表明，octocoral生殖物候受环境变化的影响，需要进一步努力，以阐明长期影响为R.叶霉菌在红海北部人口。