Chemical Ecology of Sponges on Caribbean Reefs

海绵是海底海洋群落的重要组成部分，在当代加勒比珊瑚礁中占主导地位。它们组织的有机提取物产生了大量不寻常的化合物，这些化合物不参与初级代谢，它们的生态功能才刚刚开始被理解。该项目将解决加勒比海海绵的防御问题，这是一个分类学和化学相当好的描述。由于珊瑚礁海绵是丰富的，固着的，精心推定的结构和化学防御，并受到放牧的通才和专业的捕食者，他们提供了一个有用的组测试的基本假设提出的陆地生态学家对植物防御机制。这项研究有三个主要目标。第一个是扩大海绵化感作用的调查，包括海绵珊瑚的相互作用。通过结合使用潜水脉冲调幅荧光法的修改后的凝胶为基础的现场测定，初步结果显示，珊瑚光合作用和漂白的海绵代谢物的差异影响。这种方法将被用来测试海绵和珊瑚之间的干扰竞争和所涉及的代谢物的身份的几个假设。第二个目标是测试的两个主要类别的珊瑚礁海绵的资源分配的假设：化学防御物种和那些可口的海绵吃鱼。初步结果表明，后者比前者愈合伤口更快，在野外的笼中实验中生长更快。该项目将包括对每一类中几个物种的生长和繁殖产量的比较。第三个目的是调查光合共生菌在巨型海绵Xestospongia穆塔的化学防御和漂白中的重要性。该项目对本科生和研究生以及一名富布赖特博士后学者的支持和培训、来自六个国家的科学家和学生在三次研究航行中的合作以及基于网络的外联活动（包括关于X的人口统计学和漂白的链接）的更广泛影响。穆塔和加勒比海海绵的摄影关键。这些结果将有助于判断陆地生态系统研究中得出的化学防御理论的普遍适用性，同时促进对珊瑚礁环境中底栖无脊椎动物、其捕食者及其竞争对手之间复杂关系的了解。

Sponges are important components of benthic marine communities, and are dominant on contemporary Caribbean coral reefs. Organic extracts of their tissues have yielded a wealth of unusual chemical compounds that are not involved in primary metabolism, and their ecological functions are only beginning to be understood. This project will address the defenses of Caribbean sponges, a group whose taxonomy and chemistry is fairly well described. Because reef sponges are abundant, sessile, elaborate putative structural and chemical defenses, and are subject to grazing from generalist and specialist predators, they provide a useful group for testing fundamental hypotheses proposed by terrestrial ecologists about plant defensive mechanisms. The research has three primary objectives. The first is to extend investigations of sponge allelopathy to include sponge-coral interactions. By combining a modified gel-based field assay with the use of diving pulse amplitude modulated fluorometry, preliminary results have shown differential effects of sponge metabolites on coral photosynthesis and bleaching. This method will be used to test several hypotheses about interference competition between sponges and corals and the identities of the metabolites involved. The second objective is to test hypotheses regarding resource allocation by the two dominant classes of reef sponges: chemically defended species and those that are palatable to sponge-eating fishes. Preliminary results have demonstrated that the latter class heals wounds faster than the former, and grows faster in caging experiments in the field. This project will include comparisons of growth and reproductive output of several species in each class. The third objective is to investigate the importance of photosymbionts in the chemical defense and bleaching of the giant barrel sponge Xestospongia muta. The broader impacts of the project support and training for undergraduate and graduate students and for a Fulbright post-doctorate scholar, collaboration among scientists and students from six nations on three research cruises, and web-based outreach, including links on demography and bleaching of X. muta and a photographic key to the sponges of the Caribbean. The results will be useful in judging the general applicability of chemical defense theories derived from studies of terrestrial ecosystems, while advancing an understanding of the complex relationships among benthic invertebrates, their predators and their competitors in coral reef environments.