Graduate School of Systems Life Science, Kyushu University, Fukuoka, Japan.
Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
J Biol Rhythms. 2023 Apr;38(2):148-158. doi: 10.1177/07487304221135916. Epub 2022 Dec 2.
Many marine organisms synchronously spawn at specific times to ensure the success of external fertilization in the ocean. Corals are famous examples of synchronized spawning at specific lunar phases, and two distinct spawning patterns have been observed in two dominant taxa: merulinid corals spawn at regular lunar phases, several days after the full moon, whereas corals spawn at more irregular lunar phases around the full moon. Although it has been suggested that the two coral taxa have different responses to moonlight and seawater temperature, their spawning times have never been analyzed by integrating the two environmental factors, resulting in an incomplete understanding of the regulatory mechanisms of spawning. In this study, we developed a new predictive model of coral spawning days by integrating moonlight and temperature effects based on the external coincidence model for the lunar cycle. We performed model fitting using a 10-year monitoring record of coral spawning time in Taiwan. Our model successfully demonstrated the synergistic effects of moonlight and temperature on coral spawning time (days) and provided two testable hypotheses to explain the different spawning patterns regarding the preparation (maturation) process for spawning and the sensitivity to moonlight at different circadian phases: (1) corals may have an earlier onset and longer period of preparation for spawning than merulinid corals; and (2) merulinid corals may use moonlight signals near sunset, while corals may have a similar onset at approximately midnight. This is the first study to indicate the difference in circadian phase-dependent moonlight sensitivities between coral taxa, providing a basis for underlying coral spawning mechanisms for rhythmic studies.
许多海洋生物会在特定时间同步产卵，以确保海洋中外源受精的成功。珊瑚是在特定月相同步产卵的著名例子，在两个占主导地位的分类群中观察到两种不同的产卵模式：merulinid 珊瑚在满月后几天的固定月相产卵，而 corals 在满月前后更不规则的月相产卵。虽然有人认为这两个珊瑚类群对月光和海水温度有不同的反应，但它们的产卵时间从未通过整合这两个环境因素进行分析，导致对产卵调节机制的理解不完整。在这项研究中，我们根据月球周期的外部巧合模型，通过整合月光和温度效应，开发了一种新的珊瑚产卵日预测模型。我们使用台湾珊瑚产卵时间的 10 年监测记录进行模型拟合。我们的模型成功地证明了月光和温度对珊瑚产卵时间（天数）的协同作用，并提供了两个可测试的假设来解释不同的产卵模式，即关于产卵的准备（成熟）过程和对不同昼夜节律相位月光的敏感性：(1) corals 可能比 merulinid corals 更早开始并具有更长的产卵准备期；(2) merulinid corals 可能在日落附近使用月光信号，而 corals 可能在大约午夜同时开始。这是第一项表明珊瑚类群在昼夜节律相关的月光敏感性方面存在差异的研究，为节律性研究提供了潜在的珊瑚产卵机制基础。
