Abstract

Understanding population dynamics is a long-standing objective of ecology, but the need for progress in this area has become urgent. For coral reefs, achieving this objective is impeded by a lack of information on settlement versus post-settlement events in determining recruitment and population size. Declines in coral abundance are often inferred to be associated with reduced densities of recruits, which could arise from mechanisms occurring at larval settlement, or throughout post-settlement stages. This study uses annual measurements from 2008 to 2021 of coral cover, the density of coral settlers (S), the density of small corals (SC), and environmental conditions, to evaluate the roles of settlement versus post-settlement events in determining rates of coral recruitment and changes in coral cover at Moorea, French Polynesia. Coral cover, S, SC, and the SC:S ratio (a proxy for post-settlement success), and environmental conditions, were used in generalized additive models (GAMs) to show that: (a) coral cover was more strongly related to SC and SC:S than S, and (b) SC:S was highest when preceded by cool seawater, low concentrations of Chlorophyll a, and low flow speeds, and S showed evidence of declining with elevated temperature. Together, these results suggest that changes in coral cover in Moorea are more strongly influenced by post-settlement events than settlement. The key to understanding coral community resilience may lie in elucidating the factors attenuating the bottleneck between settlers and small corals.

中文翻译：

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法属波利尼西亚莫雷阿岛的珊瑚补充和恢复是由定居后早期事件而非定居推动的

摘要

了解种群动态是生态学的一个长期目标，但该领域取得进展的需求已变得迫切。对于珊瑚礁来说，在确定珊瑚礁补充和种群规模时，由于缺乏关于定居与定居后事件的信息，阻碍了实现这一目标。珊瑚丰度的下降通常被推断与新珊瑚密度的减少有关，这可能是由于幼虫定居或整个定居后阶段发生的机制引起的。本研究使用 2008 年至 2021 年珊瑚覆盖率、珊瑚定居者密度 (S)、小珊瑚密度 (SC) 和环境条件的年度测量值，来评估定居与定居后事件在确定珊瑚礁率方面的作用。法属波利尼西亚莫雷阿岛的珊瑚补充和珊瑚覆盖变化。广义加性模型 (GAM) 中使用珊瑚覆盖率、S、SC 和 SC:S 比率（定居后成功的代表）和环境条件来表明：(a) 珊瑚覆盖率与SC 和 SC:S 高于 S，并且 (b) 当前面有冷海水、低浓度叶绿素 a 和低流速时，SC:S 最高，并且 S 显示出随温度升高而下降的证据。总之，这些结果表明莫雷阿岛珊瑚覆盖的变化受到定居后事件的影响比定居的影响更大。了解珊瑚群落恢复力的关键可能在于阐明减轻定居者和小珊瑚之间瓶颈的因素。