Data from: Characterising the ecological trade-offs throughout the early ontogeny of coral recruitment

Drivers of recruitment in sessile marine organisms are often poorly understood, due to the rapidly changing requirements experienced during early ontogeny. The complex suite of physical, biological and ecological interactions beginning at larval settlement involve a series of trade-offs that influence recruitment success. For example, while cryptic settlement within complex microhabitats is a commonly observed phenomenon in sessile marine organisms, it is unclear whether trade-offs between competition in cryptic refuges and predation on exposed surfaces leads to higher recruitment. To explore the trade-offs during the early ontogeny of scleractinian corals, we combined field observations with laboratory and field experiments to develop a mechanistic understanding of coral recruitment success. Multiple experiments conducted over 15 months in Palau (Micronesia) allowed a mechanistic approach to study the individual factors involved in recruitment: settlement behaviour, growth, competition, and predation, as functions of microhabitat and ontogeny. We finally developed and tested a predictive recruitment model with the broader aim of testing whether our empirical insights explained patterns of coral recruitment and quantifying the relative importance of each trade-off. Coral settlement was higher in crevices than exposed microhabitats, but post-settlement bottlenecks differed markedly in the presence (uncaged) and absence (caged) of predators. Incidental predation by herbivores on exposed surfaces at early post-settlement (<3 mm) stages and targeted predation by corallivores at late post-settlement (3-10 mm) stages exceeded competition in crevices as major drivers of mortality. In contrast, when fish were excluded, competition with macroalgae and heterotrophic invertebrates intensified mortality, particularly in crevices. As a result, post-settlement trade-offs were reversed, and recruitment was >2-fold higher on exposed surfaces than crevices. Once post-settlement bottlenecks were overcome, survival was higher on exposed surfaces regardless of fish exclusion. However, maximum recruitment occurred in crevices of uncaged treatments, being 9-fold higher than caged treatments. Overall, we characterise recruitment success throughout the earliest life-history stages of corals and uncover some intriguing trade-offs between growth, competition and predation, highlighting how these change and even reverse during ontogeny and under alternate disturbance regimes.固着海洋生物（sessile marine organisms）在早期个体发育（early ontogeny）过程中往往面临快速变化的生存需求，因此其招募驱动机制通常尚不明确。从幼虫附着（larval settlement）阶段起便启动的复杂物理、生物与生态交互网络，包含一系列影响招募成功率的权衡取舍（trade-offs）。例如，在复杂微生境（microhabitats）中开展隐蔽附着（cryptic settlement）是固着海洋生物的常见现象，但目前仍不清楚隐蔽庇护所内的种间竞争与暴露表面上的捕食压力之间的权衡，是否能够提升招募成功率。为探究石珊瑚（scleractinian corals）早期个体发育阶段的这类权衡关系，我们结合野外观测与室内外实验，构建了对珊瑚招募成功的机制性认知（mechanistic understanding）。我们在密克罗尼西亚（Micronesia）帕劳（Palau）开展了为期15个月的多组实验，通过机制性研究方法，分析微生境与个体发育阶段对珊瑚附着行为（settlement behaviour）、生长、种间竞争及捕食压力等关键招募相关因子的调控作用。最后，我们构建并验证了一个预测性招募模型，其核心目标为验证我们的实证观测能否解释珊瑚招募的野外格局，并量化各类权衡关系的相对重要性。研究结果显示：珊瑚在裂缝微生境中的附着率显著高于暴露微生境，但附着后的生存瓶颈（post-settlement bottlenecks）在有（无笼组，即存在捕食者，uncaged）与无（有笼组，即排除捕食者，caged）捕食者的环境中呈现出显著差异。在早期附着后阶段（体长<3mm），植食性动物（herbivores）对暴露表面的偶然捕食，以及晚期附着后阶段（体长3-10mm）的食珊瑚动物（corallivores）针对性捕食，均超过了裂缝内的种间竞争，成为主要的死亡驱动因子。与之相反，在排除鱼类的有笼组中，与大型藻类（macroalgae）和异养无脊椎动物（heterotrophic invertebrates）的种间竞争加剧了死亡率，尤其在裂缝微生境中更为突出。这使得附着后的权衡关系发生逆转，暴露表面的招募成功率较裂缝微生境高出2倍以上。当突破附着后的生存瓶颈后，无论是否存在捕食者，暴露表面上的珊瑚存活率均更高。但无笼组的裂缝微生境中招募成功率最高，较有笼组高出9倍。综上，我们完整刻画了珊瑚最早生活史阶段的招募成功模式，揭示了生长、种间竞争与捕食压力之间存在的有趣权衡关系，并阐明了这些权衡如何随个体发育与不同干扰制度（disturbance regimes）发生变化甚至逆转。