[RESOURCE] Human Impacts on Coral Reef Biodiversity: Are Responses In Species Richness Comparable Across Size Classes of Associated Species?

简介珊瑚礁被认为是海洋中物种最丰富的生态系统，但它们也可能是最受威胁的(例如Carpenter等人，2008 Science 321：560-563)。虽然对某些珊瑚礁生物群的生物多样性模式进行了很好的研究，特别是造礁珊瑚、鱼类和一些底栖大型动物组成，但对所谓的隐形动物群中许多种群的多样性和分布研究得很少，基线多样性也不是很清楚(Knowlton&Jackson，2008 PLOBiol 6：E54；Plaisance等人，2009年珊瑚礁28：977-986)。因此，我们对人类对珊瑚礁的影响对生物多样性的整体影响的理解很差。该项目将侧重于评估选定的珊瑚礁隐形动物群的多样性，并审查生物多样性的这一组成部分与相对原始的和受影响相对较大的珊瑚礁上的造礁珊瑚、鱼类和显眼的大型动物之间的关系。调查方法将基于外礁背风侧的线形样带和样方，将用于调查珊瑚、鱼类和显著大型动物的多样性。这些将与使用形态学和分子方法相结合的对收集的死亡珊瑚头、珊瑚碎屑和沉积物的隐形动物的研究进行比较。假设本项目将重点检验两个假设：(I)栖息于各种亚生境的珊瑚礁隐形动物在多种分类群和大小类别的生物中具有高度的物种丰富度。(Ii)根据以前的研究(如Sandin等人，2008年)，不同类群对人类影响的反应有很大差异。我们还预计，不同物种的生态协会对影响的反应会有所不同(例如，食草动物、捕食者、碎屑食者、悬浮食者)。方法该项目将比较相对原始的珊瑚礁环境与受到不同程度影响的环境中的生物多样性。将进行比较的地点包括：查戈斯群岛(轻度影响)、马达加斯加(中度影响)和菲律宾(重度影响)。如果其中任何一个被证明是不切实际的，替代地点是塞舌尔和/或东非。Case合作伙伴、ZSL在实地工作方面的协助以及探险队的可用性将决定这项工作的确切位置。将从在这些区域内工作的伙伴非政府组织那里获得援助。将通过实地测量来评估珊瑚礁的水质。观察珊瑚死亡率、珊瑚礁捕捞的证据、藻类的存在和鱼类群落结构将有助于评估珊瑚礁的状况。将使用数字拍摄的直线截面法测量外部珊瑚礁的背风面，以记录底层覆盖率，并使用腰带截面法进行水下视觉普查，以评估鱼类群落的多样性。样方将被用来调查巨型动物无脊椎动物。将收集死珊瑚头部，以及收集碎石和沉淀物。动物将从野外的珊瑚和瓦砾中提取出来。沉积物样本将被保存并运往牛津大学。分子条形码方法将被用来评估从珊瑚和瓦砾中提取的精选隐形动物群体的多样性。沉积物将被提取环境DNA，如果从NERC高通量分子设施获得额外资金，将使用超级测序进行分析。结果学生身份应该提供关于珊瑚礁群落中很少被研究的元素所构成的多样性的大小的有价值的数据。与珊瑚礁生物的其他大小类别/公会相比，所获得的关于人类对珊瑚礁的影响的数据将是新的，对珊瑚礁的监测和管理具有直接重要性。该项目将为珊瑚礁生物的分类和序列数据库提供新的信息。

INTRODUCTION Coral reefs are regarded as the most species rich ecosystems in the oceans but they are also probably the most threatened (e.g. Carpenter et al., 2008 Science 321: 560-563). Whilst patterns of biodiversity are well studied for some groups of coral reef organisms, especially reef-forming corals, fish and some benthic megafaunal components, the diversity and distribution of many groups within the so-called cryptofauna are poorly studied and baseline diversity is not well understood (Knowlton & Jackson, 2008 PLOBiol 6: e54; Plaisance et al., 2009 Coral Reefs 28: 977-986). As a result we have a poor understanding of the overall implications of human impacts on coral reefs for biodiversity. This project will focus on assessment of the diversity of select groups of reef cryptofauna and examining the relationship between this component of biodiversity and that of reef-forming corals, fish and conspicuous megafauna on relatively pristine to relatively impacted corals reefs. Survey methods, based on line transects and quadrats on the leeward side of outer reefs, will be used to survey the diversity of corals, fish and conspicuous megafauna. These will be compared with studies on the cryptofauna of collected dead coral heads, coral rubble and sediment using a combination of morphological and molecular methods. HYPOTHESES This project will be focused on testing two hypotheses: (i) That the cryptofauna of coral reefs, inhabiting a variety of sub-habitats has a high level of species richness across multiple taxa and size classes of organisms. (ii) Based on previous studies (e.g. Sandin et al., 2008), the response of different taxa to human impacts differs significantly. We also expect responses in different ecological guilds of species to differ to impacts (e.g. grazers, predators, detritus feeders, suspension feeders). METHODS The project will compare biodiversity on relatively pristine coral reef environments compared to those that are impacted to various degrees. Locations that will be compared include: Chagos Archipelago (low impact), Madagascar (moderate impact), and the Philippines (heavy impact). Alternative sites should any of these prove impractical are the Seychelles and/or East Africa. Assistance in fieldwork from the CASE partners, ZSL, and availability of expeditions will determine the exact locations of this work. Assistance will be obtained from partner NGOs working within these regions. Coral reefs will be assessed for water quality through field measurements. Observations of coral mortality, evidence of reef fishing, presence of algae and community structure of fish will help to assess reef condition.The leeward side of outer reefs will be surveyed using transects employing digitally photographed Line Intercept Transects to record % cover of substratum and Underwater Visual Census (UVCs) using belt transects to assess the diversity of fish communities. Quadrats will be used to survey megafaunal invertebrates. Dead coral heads will be collected, as well as collections of rubble and sediment made. Animals will be extracted from coral and rubble in the field. Sediment samples will be preserved and transported to Oxford. Molecular barcoding methods will be used to assess the diversity of select groups of cryptofauna extracted from coral and rubble. Sediment will be subject to extraction of environmental DNA and, if additional funding is obtained from the NERC high-throughput molecular facilities, analysed using hypersequencing. OUTCOMES The studentship should provide valuable data on the magnitude of diversity comprised by elements of the reef community that are rarely studied. Data obtained on human impacts on corals reefs on reef cryptofauna, in comparison to other size classes / guilds of reef organisms will be novel and of immediate importance in monitoring and management of coral reefs. The project will contribute new information on taxonomy and to sequence databases of reef organisms.