Coral reef development in response to large amplitude internal waves and monsoon impact@en

The Andaman Sea and other macrotidal semi-enclosed tropical seas feature large amplitude internal waves (LAIW). Although LAIW induce strong fluctuations i.e. of temperature, pH, and nutrients, their influence on reef development is so far unknown. A better-known source of disturbance is the monsoon affecting corals due to turbulent mixing and sedimentation. Because in the Andaman Sea both, LAIW and monsoon, act from the same westerly direction their relative contribution to reef development is difficult to discern. Here, we explore the framework development in a number of offshore island locations subjected to differential LAIW- and SW-monsoon impact to address this open question. Cumulative negative temperature anomalies - a proxy for LAIW impact - explained a higher percentage of the variability in coral reef framework height, than sedimentation rates which resulted mainly from the monsoon. Temperature anomalies and sediment grain size provided the best correlation with framework height suggesting that so far neglected subsurface processes (LAIW) play a significant role in shaping coral reefs.安达曼海及其他大潮差半封闭热带海域广泛发育大振幅内波（large amplitude internal waves, LAIW）。尽管大振幅内波会引发温度、pH值与营养盐等要素的剧烈波动，但其对珊瑚礁发育的影响迄今仍不明晰。另一类为学界所熟知的干扰源为季风——其通过湍流混合与沉积作用对珊瑚造成影响。由于在安达曼海海域，大振幅内波与季风均源自同一西风方向，二者对珊瑚礁发育的相对贡献难以区分。本研究选取若干受不同程度大振幅内波与西南季风影响的离岸岛礁点位，探究其礁体发育过程，以解决这一悬而未决的科学问题。相较于主要由季风驱动的沉积速率，作为大振幅内波影响代用指标的累积负温度异常，对珊瑚礁礁体高度变化的解释度更高。温度异常与沉积物粒度与礁体高度的相关性最优，这表明此前被忽视的次表层过程（大振幅内波）在塑造珊瑚礁形态中发挥着重要作用。