Unravelling the drivers of coral reproductive phenology and synchrony

石珊瑚是珊瑚礁的生态系统工程师，珊瑚礁是地球上生物多样性最丰富的海洋生态系统之一。珊瑚礁是四分之一海洋物种的家园，通过渔业、旅游业和海岸保护，为全世界数亿人的福祉和生计提供支持。大多数珊瑚品种是广播产卵者，它们依靠同步产卵事件作为种群补充和适应的基本过程。大多数珊瑚在短的季节性期间同步产卵，这些事件的时间取决于环境线索。鉴于大多数珊瑚在水柱中释放配子的时间窗口很短，因此受精取决于珊瑚群落根据适当的环境线索调整其繁殖时间。此外，它们还依赖于释放具有高度同步性的配子，以确保在有利的环境条件下发生异交。海洋表面温度、太阳日照、风速、月相和周期已被证明会影响珊瑚产卵，并对一个月或一周的产卵负责，但珊瑚将这一事件定在某一天的机制仍不清楚。考虑到一些环境因素在生殖物候学中的重要性，气候变化的影响可能会破坏产卵同步，对种群生存能力产生长期影响。尽管珊瑚礁在维持生态系统功能和为许多沿海社区提供服务方面发挥着关键作用，但仍有必要了解全球范围内人类影响如何影响珊瑚的繁殖时间和同步。直到最近，由于缺乏珊瑚繁殖物候的大规模数据集，以及与操纵季节环境周期的实验相关的技术挑战，所描述的气候变化对珊瑚繁殖同步的影响受到限制。在此之前，环境参数的影响已经在宽时空尺度上进行了研究。（月平均平均值），因此，确定珊瑚产卵同步的适当环境线索仍然是一个挑战。在我的博士学位期间，我的目标是i)确定哪些气候驱动因素与产卵物候学和分类群和生态区域内的同步性更相关，ii)调查哪些过程和气候驱动因素在不同的物候策略（如分裂产卵）背后，iii)评估几个分类群对选定驱动因素变化的反应，以确定哪些科或物种更容易经历生殖物候的中断和产卵同步的可能中断。对于这项任务，我将使用现在、过去和预测的未来气候情景来创建生态模型，iv)确定珊瑚产卵不同步的高风险区域，创建考虑物候变化的预测性物种分布模型。这些模型将有助于绘制出产卵中断风险的地图，确定哪些物种更容易受到不同驱动因素的影响，从而有助于保护珊瑚礁。我正在使用最近编制的珊瑚产卵时间（CSD）大型数据库，其中包括超过300种珊瑚的6000个产卵时间或日期的个人观察，以研究产卵同步和物候的时空模式。我将使用统计模型来检验精细时空尺度气候驱动因素对产卵时间的影响。此外，我将进行实地和实验室实验，以测试温度，月亮周期和光照制度的影响，以解开它们对珊瑚产卵物候同步的影响。

Scleractinian corals are the ecosystem engineers of coral reefs, one of the most biodiverse marine ecosystems on the planet. Coral reefs are home to a quarter of all marine species and support the wellbeing and livelihoods of hundreds of millions of people worldwide through fisheries, tourism and coastal protection. Most coral species are broadcast spawners which relay on synchronous spawning events as an essential process for the replenishment and adaptation of populations. Most corals spawn synchronously during short seasonal periods and the timing of these events depends on environmental cues. Given most corals present a short time window in which they release gametes in the water column, fertilization depends on coral colonies adjusting their reproductive timing following the appropriate environmental cues. Moreover, they also depend on releasing gametes with a high degree of synchrony to ensure that outcrossing happen in beneficial environmental conditions. Sea surface temperature, solar insolation, wind speed, lunar phase and cycle have been demonstrated to influence coral spawning and be responsible for month or week of spawning but the mechanisms corals time this event to a particular day still remain unclear. Given the importance of several environmentalcuesin reproductive phenology, climate change impacts could disrupt spawning synchrony, with long-term consequences for population viability.Despite the key role thatcoral reefsplayfor maintaining ecosystem functions and the services they provide to many coastal communities,there is still a need to understand how global-scale human impacts affect coral reproductive timing and synchrony.Until recently, the described impacts of climate change on coral reproductive synchrony have been limitedby a lack of large-scale datasets on coral reproductive phenology, and technical challenges associated with experiments to manipulate seasonal environmental cycles.Previously,the effect of environmental parameters hasbeen studied using broadspatiotemporal scale(e.g., monthly averaged means)and,therefore,identifyingappropriate environmental cues for coral spawning synchrony remains a challenge. Duringmy Ph.D.I aim to i) determine which climate drivers are more relevant for spawning phenology and synchrony within taxa and ecoregions,ii) investigate which processes and climate drivers are behind different phenological strategies such as split spawning, highlysynchronousvs asynchronousreproductive strategies within assemblages,iii) Evaluate the responses of several taxa to changes in the selected drivers in order to determine which families or species could be more susceptible to experience disruptions in their reproductive phenology and possible breakdowns in spawning synchrony. For this task I will use present, past and predicted future climate scenarios to create ecological models, iv) to identify areas of higher risk to experience asynchronies in coral spawning, creating predictive species distribution models accounting for phenological changes. Such models will help to develop maps of risk of spawning breakdown identifying which species are more vulnerable to different drivers which could help to preserve coral reefs. I am working with a recently compiled, large database on coral spawning timing (CSD), including 6000 individual observations of the time or day of spawning for over 300 coral species, to investigate spatial and temporal patterns of spawning synchrony and phenology. I will use statistical models to test he effect of fine spatiotemporal scale climate drivers on spawning timing. Additionally, I will conduct field and laboratory experiments to test the effects of temperature, lunar cycle and light regime in order to disentangle their effect in coral spawning phenology synchrony.