RUI: Assessing the Chemical Defenses of Caribbean Invertebrates

RUI：评估加勒比无脊椎动物的化学防御能力

• 批准号: 0095724
• 负责人: Joseph Pawlik
• 金额: $ 44万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0095724&HistoricalAwards=false
• 关键词: RUI; Assessing; Chemical; Defenses; Caribbean

Sponges, gorgonians, and ascidians are important components of benthic marine communities, particularly coral reefs. Organic extracts of their tissues have yielded a wealth of unusual chemical compounds that are not involved in primary metabolism, and their biological functions are mostly unknown. One commonly held theory is that these compounds are distasteful to potential predators, but they may also protect from fouling or overgrowth. This study is a continuation of a very successful RUI research program designed to assess the defenses of Caribbean sponges, a group whose taxonomy and chemistry is fairly well described. Because reef sponges, gorgonians and ascidians 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.Investigations of antipredatory structural and chemical defenses will be extended from the previous study to include Caribbean gorgonians and ascidians, using the successful techniques previously applied to sponges. In particular, optimal defense theory will be tested with ascidians, which elaborate both inorganic and organic chemical defenses. Metabolites of invertebrate species that have yielded deterrent crude extracts will be identified by bioassay-directed fractionation, resulting in a better understanding of the structure-function relationships of chemical defenses. Intraspecific patterns of metabolite expression will be examined to determine whether they conform to optimal defense theory. Hypotheses regarding resource allocation between defensive chemistry and growth, reproduction, and regeneration will be tested by manipulating chemically defended and non-defended reef sponges in the field. The hypothesis that fish predation limits sponge distributions on reefs will be tested by comparing transect data from reefs where sponge-eating fishes are abundant (Bahamas, Florida Keys) to reefs where fish predators are rare due to natural (Bermuda) or anthropogenic causes (Jamaica, Barbados). The hypothesis that sponge secondary metabolites function as antifouling and anti-overgrowth defenses will be further tested in the field and laboratory with gel-based assays, and these techniques will be used to isolate the active metabolites. Field experiments will be conducted to determine the rates at which active metabolites are expressed by sponges onto their surfaces or into seawater.Overall, this research program will continue to develop one of the most systematic and complete investigations of chemical defenses of tropical invertebrates, while at the same time providing important educational opportunities for students at an RUI institution. The results will be useful in judging the general applicability of chemical defense theories derived from studies of terrestrial ecosystems, while advancing our understanding of the complex relationships between benthic invertebrates, their predators and their competitors in coral reef environments.

海绵、柳珊瑚和海鞘是底栖海洋群落的重要组成部分，特别是珊瑚礁。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，它们的生物学功能大多是未知的。一种普遍持有的理论是，这些化合物对潜在的捕食者来说是令人厌恶的，但它们也可以防止污垢或过度生长。这项研究是一个非常成功的RUI研究计划的延续，该计划旨在评估加勒比海海绵的防御能力，这是一个分类学和化学相当好的描述。由于珊瑚礁海绵，柳珊瑚和海鞘是丰富的，固着的，精心假定的结构和化学防御，并受到放牧从通才和专业的捕食者，他们提供了一个有用的群体，为测试基本假设提出的陆地生态学家对植物防御机制。调查的抗掠夺结构和化学防御将从以前的研究扩展到包括加勒比柳珊瑚和海鞘，使用先前应用于海绵的成功技术。特别是，最佳防御理论将与海鞘，阐述了无机和有机化学防御测试。代谢的无脊椎动物物种，产生威慑粗提取物将被确定的生物测定导向分馏，从而更好地了解化学防御的结构-功能关系。将检查代谢物表达的种内模式，以确定它们是否符合最佳防御理论。关于防御化学和生长，繁殖和再生之间的资源分配的假设将通过操纵化学防御和非防御珊瑚礁海绵在该领域进行测试。鱼捕食限制珊瑚礁上的海绵分布的假设将通过比较从珊瑚礁吃海绵的鱼类丰富（巴哈马群岛，佛罗里达键）的珊瑚礁，鱼类捕食者是罕见的，由于自然（百慕大）或人为原因（牙买加，巴巴多斯）的断面数据进行测试。海绵次生代谢产物作为抗真菌和抗过度生长防御的假设将在田间和实验室中用基于凝胶的测定法进行进一步测试，这些技术将用于分离活性代谢产物。通过现场实验，确定活性代谢物在海绵表面或海水中的表达速率。总的来说，该研究项目将继续发展热带无脊椎动物化学防御最系统和完整的研究之一，同时为RUI机构的学生提供重要的教育机会。这些结果将有助于判断来自陆地生态系统研究的化学防御理论的普遍适用性，同时促进我们对珊瑚礁环境中底栖无脊椎动物，捕食者和竞争对手之间复杂关系的理解。