Acute effects of back-to-back hurricanes on the underwater light regime of a coral reef
Acute effects of back-to-back hurricanes on the underwater light regime of a coral reef
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DOI：
10.1007/s00227-018-3459-z
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发表时间：
2019-01
期刊：
影响因子：
2.4
通讯作者：
P. Edmunds;G. Tsounis;R. Boulon;L. Bramanti
中科院分区：
文献类型：
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作者：
P. Edmunds;G. Tsounis;R. Boulon;L. Bramanti
影响珊瑚礁的一些最著名的干扰是风暴，但它们对光线的影响却知之甚少。在这里，我们描述了在2017年8月17日至2017年11月30日期间发生的两次飓风和多个热带海浪期间，美属维尔京群岛圣约翰（18°18′37.04N，63°43′23.17W）附近礁石上的水下灯光。光合有效辐射（PAR）记录在19米的深度和表面，和降雨量的浊度影响水下光的原因进行了测量。飓风厄玛和玛丽亚使每日最大水下光合作用光子通量密度（PPFD）降至< 14 µmol photons m−2s−1（<地表PPFD的0.001%），9月1日至11月30日期间的降雨量（107 cm）高于1972年以来同期的记录。至少自2014年以来，水下PPFD的这些减少是前所未有的，相应的漫射衰减系数值（Kd-PAR 0.268 -0.426）是珊瑚礁记录的最低值之一。我们的研究揭示了飓风使光栖息地暂时无光的能力，超过69天（相对于2016年），有助于减少20%的总和，每日综合水下PPFD。大量减少水下PPFD光合类群的负面影响，但通过浊度，减少水下光，他们创造了悬浮饲料无脊椎动物的人口增长的机会。
Some of the best-known disturbances affecting coral reefs are storms, yet their impacts on light are poorly known. Here, we describe the underwater light on a reef off St. John, US Virgin Islands (18°18′37.04N, 63°43′23.17W), during two hurricanes and multiple tropical waves that occurred between 17 August 2017 and 30 November 2017. Photosynthetically active radiation (PAR) was recorded at 19-m depth and at the surface, and rainfall was measured as a cause of turbidity affecting underwater light. Hurricanes Irma and Maria reduced maximum daily underwater photosynthetic photon flux density (PPFD) to < 14 µmol photons m−2s−1(< 0.001% of surface PPFD) and, from 1 September to 30 November, were associated with rainfall that was higher (107 cm) than has been recorded over this period since 1972. These reductions in underwater PPFD are unprecedented since at least 2014, and the corresponding values of the diffuse attenuation coefficients (Kd-PAR0.268–0.426) are among the lowest recorded on a coral reef. Our study reveals the capacity for hurricanes to render a photic habitat temporarily aphotic, and over 69 days (and relative to 2016), to contribute to a 20% reduction in summed, daily integrated underwater PPFD. Large reductions in underwater PPFD have negative implications for photosynthetic taxa, but through the turbidity that reduces underwater light, they create opportunities for population growth by suspension feeding invertebrates.