RUI: Experimental Studies on Multi-Species Zooxanthella Communities and Coral Bleaching

造礁珊瑚是异养动物和光养鞭毛内共生生物（虫黄藻）的专性结合体。科学家们对一种明显的应激反应——珊瑚白化——产生了兴趣，这种反应涉及到这种共生关系的“破裂”，偶尔会导致生态破坏性的珊瑚死亡。人们之所以对珊瑚白化感兴趣，是因为相信这些事件在世界范围内正在增加，而且它们作为环境变化的敏感生物指标具有潜在价值。然而，我们对珊瑚白化的生态和原因的理解仍然存在很大差距。这些空白阻碍了将珊瑚白化与环境问题联系起来的尝试。最近完成的关于加勒比地区主要和研究最多的珊瑚——环斑珊瑚和费沃拉塔珊瑚的研究揭示了一个与珊瑚白化直接相关的根本性误解。与之前被广泛接受的珊瑚只有一种共生体的观点相反，这些珊瑚拥有三个虫黄藻分类群的动态群落，这些群落主要由环境辐照度梯度组织。这一现象简单地解释了珊瑚白化生态学中一个长期存在的问题——珊瑚群落之间和内部的一种令人困惑的变化。因为它颠覆了几十年来研究珊瑚的一个基本前提，这一发现也为实验研究开辟了新的和意想不到的机会。本项目将在多物种虫黄藻群落和环境胁迫的明确背景下，对Montastraea spp.的环境生物学进行分析。先前对这些群落的研究表明，它们与得到更好研究的陆生植物群落相似。

Reef-building corals are obligate associations of heterotrophic animals and phototrophic dinoflagellate endosymbionts (zooxanthellae). Scientists have become interested in a conspicuous stress response -- coral bleaching -- that involves the `breakdown` of this symbiosis, occasionally followed by ecologically devastating coral mortality. Interest in coral bleaching is motivated by the belief that these events are increasing world-wide, and by their potential value as a sensitive bioindicator of environmental change. However, large gaps in our understanding of both the ecology and causes of coral bleaching remain. These gaps frustrate attempts to relate coral bleaching to environmental issues. Recently completed studies on the Caribbean's dominant and most studied corals, Montastraea annularis and M. faveolata, revealed a fundamental misunderstanding that relates directly to coral bleaching. Contrary to the earlier, widely accepted belief that corals harbor only one symbiont, these corals host dynamic communities of three taxa of zooxanthellae that are primarily organized by gradients of ambient irradiance. This phenomenon explained a longstanding issue in coral bleaching ecology -- an otherwise bewildering variation, both among and within coral colonies -- in simple terms. Because it upsets a basic premise on which corals have been studied for decades, this discovery also opens up new and unexpected opportunities for experimental research. This project will analyze the environmental biology of Montastraea spp. in the explicit contexts of multi-species zooxanthella communities and environmental stress. Previous studies of these communities imply parallels with much better studied communities of terrestrial plants.