Internal waves influence the thermal and nutrient environment on a shallow coral reef
Internal waves influence the thermal and nutrient environment on a shallow coral reef
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DOI：
10.1002/lno.11162
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发表时间：
2019-09-01
影响因子：
4.5
通讯作者：
Davis, Kristen A.
中科院分区：
文献类型：
--
作者：
Reid, Emma C.;DeCarlo, Thomas M.;Davis, Kristen A.
内波可通过次温跃层水向海岸的输送和混合进入近岸地区，从而影响沿海生态系统的水性质。2014年6月，在南海北部中国海域的东沙环礁进行了现场实验，研究了内波对珊瑚礁的影响。仪器包括一个分布式温度传感系统，该系统解决了从泻湖到前礁50米深的4公里跨礁区域的空间和时间上的连续温度测量。我们的观察表明，在夏季，浅水环礁上浅海的内波定期向岸边输送寒冷的、营养丰富的水，改变了前礁的近地表水域特性。这些水通过潮汐、破碎的表面波和风力驱动的水流被输送到礁顶的岸边，在那里它显著改变了礁坪上的水温和营养物质浓度。我们发现，如果没有内波对前礁的强迫，礁坪上的温度可能高达2.0摄氏度+/-0.2摄氏度。此外，我们估计，在没有内波的情况下，采暖周的变化为0.7摄氏度-周变暖，这显著增加了东沙环礁发生更严重漂白事件的可能性。此外，利用研究期间在前礁收集的营养样本，我们估计，有内波的情况下，岸上瞬时硝酸盐通量大约是没有内波的情况下的四倍。这项工作突出了内波作为塑造近岸环境的物理机制的重要性，并可能支持珊瑚礁的弹性。
Internal waves can influence water properties in coastal ecosystems through the shoreward transport and mixing of subthermocline water into the nearshore region. In June 2014, a field experiment was conducted at Dongsha Atoll in the northern South China Sea to study the impact of internal waves on a coral reef. Instrumentation included a distributed temperature sensing system, which resolved spatially and temporally continuous temperature measurements over a 4-km cross-reef section from the lagoon to 50-m depth on the fore reef. Our observations show that during summer, internal waves shoaling on the shallow atoll regularly transport cold, nutrient-rich water shoreward, altering near-surface water properties on the fore reef. This water is transported shoreward of the reef crest by tides, breaking surface waves and wind-driven flow, where it significantly alters the water temperature and nutrient concentrations on the reef flat. We find that without internal wave forcing on the fore reef, temperatures on the reef flat could be up to 2.0 degrees C +/- 0.2 degrees C warmer. Additionally, we estimate a change in degree heating weeks of 0.7 degrees C-weeks warmer without internal waves, which significantly increases the probability of a more severe bleaching event occurring at Dongsha Atoll. Furthermore, using nutrient samples collected on the fore reef during the study, we estimated that instantaneous onshore nitrate flux is about four-fold higher with internal waves than without internal waves. This work highlights the importance of internal waves as a physical mechanism shaping the nearshore environment, and likely supporting resilience of the reef.