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

随着人为气候变化的加剧，珊瑚礁面临着海洋pH值下降和海洋温度上升的日益严重的威胁。虽然这种压力随着时间的推移稳步增加，但珊瑚礁也经历了极端的自然气候，如厄尔尼诺事件，在几个月的时间里迅速重塑了珊瑚礁的结构和功能。2014/2015年厄尔尼诺事件预报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具弹性，并确定珊瑚中特定类型的藻类内共生体的存在是否可以预测其珊瑚宿主生存温度胁迫的能力。通过研究有记录的人类使用和污染梯度的偏远地点的珊瑚礁，调查人员将能够梳理厄尔尼诺引起的温度变化对珊瑚礁的影响与当地对珊瑚礁的影响。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最脆弱，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，该地点预计将在厄尔尼诺期间受到气候变暖的严重影响。2014年9月，大约在厄尔尼诺变暖达到峰值的3个月前，调查人员将在圣诞岛周围安装一系列海洋监测设备。在那次实地考察期间，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，用于分析夏威夷大学将使用高通量测序方法进行的共生生物群落分析，并描述圣诞岛迎风和背风地点的海洋地球化学特征。这些活动将在厄尔尼诺高峰期和厄尔尼诺后的后续行程中重复进行，以使调查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情况。在最后一次旅行中，他们将钻探几个珊瑚群体，以评估珊瑚如何从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.