RAPID Collaborative Research: Tracking coral reef impacts of the 2014/2015 El Nino event

随着人为气候变化加剧，珊瑚礁面临着海洋pH值下降和海洋温度升高带来的日益严重的威胁。随着时间的推移，这些压力源稳步增加，珊瑚礁也会经历自然极端气候，比如厄尔Niño事件，在几个月的时间里迅速重塑珊瑚礁的结构和功能。2014/2015年的El Niño事件预测为研究此类事件如何影响珊瑚礁生态系统提供了机会。这项研究将确定哪些物种对高温胁迫最有弹性，并确定珊瑚中特定类型的藻内共生体的存在是否预示着它们的珊瑚宿主在温度胁迫下生存的能力。通过研究有人类使用和污染梯度记录的偏远地区的珊瑚礁，研究人员将能够梳理出厄尔尼诺现象引起的温度变化对珊瑚礁的影响。这些信息最终将有助于确定珊瑚礁生态系统的哪些组成部分是最脆弱的，并为不同类型的珊瑚和内共生生物在变暖的世界中的生存提供预测。该项目的重点是圣诞岛（2N, 157W）的珊瑚礁，该地点预计将受到厄尔尼诺Niño期间变暖的严重影响。2014年9月，大约在厄尔尼诺Niño变暖峰值前3个月，调查人员将在圣诞岛周围安装一系列海洋监测设备。在实地考察期间，他们还将对珊瑚礁进行广泛的生态调查，收集珊瑚、水和沉积物样本，以分析共生菌群落，这些群落将在夏威夷大学使用高通量测序方法进行分析，并在圣诞岛的迎风和背风地点描述海洋地球化学特征。这些活动将在随后的El Niño峰值条件和El Niño后条件下重复进行，以使研究人员能够分别监测环境和生态系统的急性反应及其近期恢复。在最后一次旅行中，他们将钻探几个珊瑚群落，以评估珊瑚如何在骨骼形态和骨骼地球化学变化方面记录如此大的热应力。

As anthropogenic climate change intensifies, coral reefs face growing threats from associated decreases in ocean pH and increases in ocean temperature. While such stressors increase steadily through time, coral reefs also experience natural climate extremes, such as El Niño events, that rapidly reshape reef structure and function over a period of months. The El Niño event forecast for 2014/2015 presents the opportunity to study how such events affect coral reef ecosystems. This research will identify which species are most resilient to high temperature stress, and determine whether the presence of specific types of algal endosymbionts in the corals is predictive of the capacity of their coral hosts to survive temperature stress. By studying the reefs at remote sites with documented gradients in human use and pollution, the investigators will be able to tease apart the influence of El-Nino induced temperature changes from local impacts on the reef. This information will ultimately help to identify which components of the coral reef ecosystem are most vulnerable and provide a prognosis for the survival of different types of corals and endosymbionts in a warming world. This project focuses on reefs at Christmas Island (2N, 157W) - a site that is predicted to be heavily affected by warming during El Niño. In September 2014, roughly 3 months prior to peak El Niño warming, the investigators will install an array of ocean monitoring equipment around Christmas Island. During that field trip, they will also conduct extensive ecological surveys of the reef, collect coral, water and sediment samples for the analysis of Symbiodinium communities that will be analyzed at the University of Hawaii using high throughput sequencing approaches, and characterize ocean geochemistry at both windward and leeward sites on Christmas Island. These activities will be repeated in subsequent trips during peak El Niño conditions, and post El Niño conditions, to allow the investigators to monitor the acute responses of the environment and ecosystem and their near-term recovery, respectively. During the last trip, they will drill several coral colonies to assess how the corals record such a large thermal stress in terms of skeletal morphological and skeletal geochemistry changes.