Abstract The impact of global environmental change on coral reef islands is uncertain with few studies having resolved the critical controls on island formation and change. Based on detailed, topographic surveys, sediment analysis and radiometric dating, we present a multi-phase model of the formation of a large inhabited reef island in the central Indian Ocean in response to Holocene sea level dynamics and transformations in reef development and reef ecology. The initial phase of island building occurred later than elsewhere reported in the Maldives, 2500–2100 years ago during the mid-Holocene sea level highstand. The island was able to support habitation shortly thereafter. Subsequent island expansion occurred as a consequence of relative sea-level fall and emergence of the reef platform that forced a transition in reef flat ecology and dominant sediment producers that contributed to island accumulation to the southwest. Small-scale sea level oscillations (± 0.8 m) over the past two millennia have driven periods of island accumulation, that intermittently reactivate geomorphic processes around the island shoreline. Significantly, the multiple phases of island development have occurred while the island has been continuously inhabited, demonstrating the adaptive capacity of the island community to multiple phases of change. Results highlight the complexity of reef island development and indicate that future physical trajectories will vary depending on not only relative sea level change, but how such changes modify water depth and wave regimes across reef surfaces, and changes in dominant sediment producers able to contribute to island building. This interrelationship differs between sites within and between reef regions and may account for currently expanding islands on reef surfaces.

中文翻译：

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全新世海平面动力学驱动印度洋中部一个大型环礁岛的形成

摘要 全球环境变化对珊瑚礁岛屿的影响尚不确定，很少有研究解决岛屿形成和变化的关键控制问题。基于详细的地形调查、沉积物分析和辐射测年，我们提出了一个多阶段模型，用于响应全新世海平面动态以及珊瑚礁发育和珊瑚礁生态的变化，形成印度洋中部一个大型有人居住的珊瑚礁岛。岛屿建设的初始阶段比马尔代夫其他地方报道的要晚，2500-2100 年前，在全新世中期海平面高位期间。此后不久，该岛就能够支持居住。随后的岛屿扩张是由于相对海平面下降和珊瑚礁平台的出现，迫使礁坪生态和主要沉积物生产者转变，导致岛屿向西南方向堆积。过去两千年的小尺度海平面振荡 (± 0.8 m) 推动了岛屿堆积的时期，间歇性地重新激活了岛屿海岸线周围的地貌过程。值得注意的是，岛屿发展的多个阶段发生在岛屿不断有人居住的同时，展示了岛屿社区对多个阶段变化的适应能力。结果突出了礁岛发展的复杂性，并表明未来的物理轨迹将不仅取决于相对海平面变化，但是这些变化如何改变整个珊瑚礁表面的水深和波浪状态，以及能够促进岛屿建设的主要沉积物生产者的变化。这种相互关系在珊瑚礁区域内和珊瑚礁区域之间的地点之间有所不同，并且可能解释了目前珊瑚礁表面上岛屿的扩大。