Ocean acidification, due to the increase of carbon dioxide (CO₂) concentration in the atmosphere and its absorption by the oceans, affects many aspects of marine calcifying organisms' biology, including reproduction. Most of the available studies on low pH effects on coral reproduction have been conducted on tropical species under controlled conditions, while little information is reported for either tropical or temperate species in the field. This study describes the influence of decreasing pH on sexual reproduction of the temperate non-zooxanthellate colonial scleractinian Astroides calycularis, transplanted in four sites along a natural pH gradient at the underwater volcanic crater of Panarea Island (Tyrrhenian Sea, Italy). The average pH values of each site (range: pH_TS 8.07–7.40) match different scenarios of the Intergovernmental Panel on Climate Change (IPCC) for the end of the century. After 3 months under experimental conditions, the reproductive parameters of both oocytes and spermaries (abundance, gonadal index, and diameters) seem to be unaffected by low pH. However, a delay in spermary development in the pre-fertilization period and a persistence of mature oocytes in the fertilization period were observed in the most acidic site. Furthermore, no embryos were found in colonies from the two most acidic sites, suggesting a delay or an interruption of the fertilization process due to acidified conditions. These findings suggest a negative effect of low pH on A. calycularis sexual reproduction. However, long-term experiments, including the synergistic impact of pH and temperature, are needed to predict if this species will be able to adapt to climate change over the next century.

中文翻译：

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pH值降低会损害移植到二氧化碳排放口的地中海珊瑚的有性繁殖


由于大气中二氧化碳(CO ₂ )浓度的增加及其被海洋吸收，海洋酸化影响海洋钙化生物生物学的许多方面，包括繁殖。大多数关于低pH值对珊瑚繁殖影响的现有研究都是在受控条件下对热带物种进行的，而对于热带或温带物种的实地报道却很少。这项研究描述了 pH 值降低对温带非虫黄藻群居石珊瑚Astroides calyularis有性繁殖的影响，该珊瑚被移植到帕纳雷阿岛（意大利第勒尼安海）水下火山口沿自然 pH 梯度的四个地点。每个地点的平均pH值（范围：pH _TS 8.07-7.40）符合政府间气候变化专门委员会（IPCC）本世纪末的不同情景。在实验条件下 3 个月后，卵母细胞和睾丸的生殖参数（丰度、性腺指数和直径）似乎不受低 pH 值的影响。然而，在酸性最强的部位观察到受精前精子发育延迟和受精期成熟卵母细胞持续存在。此外，在两个最酸性位点的菌落中没有发现胚胎，这表明由于酸化条件，受精过程延迟或中断。这些发现表明低 pH 值对萼萼萼萼有性繁殖有负面影响。然而，需要进行长期实验，包括 pH 值和温度的协同影响，以预测该物种是否能够适应下个世纪的气候变化。