Reef refugia out of the shadows: dynamics of marginal coral reef ecosystems over the past 30 million years in the Coral Triangle

珊瑚礁是地球上最多样化的海洋生态系统，为数亿人提供了巨大的经济价值，包括渔业，旅游业和海岸保护。然而，这些好处受到珊瑚礁迅速减少的威胁，这是由于人类在地方到全球范围内的影响加速造成的。用有限的资源来应对这场珊瑚礁危机需要优先考虑保护行动，许多研究人员现在正在转向生活在典型的浅水、清澈水域栖息地之外的珊瑚礁生态系统，将其作为进一步研究的关键优先事项。有新的证据表明，这些生活在浑浊或更深水域的所谓边缘珊瑚礁可以更好地适应漂白，水质变化和其他影响。增加的漂白复原力可能是由于水中的沉积物限制了紫外线的压力，或者是因为珊瑚可能更容易利用浮游生物中的食物来源。因此，边缘珊瑚礁有可能成为有复原力的珊瑚的避难所，并可能对日益减少的清水珊瑚礁的未来恢复至关重要。然而，大多数关于边缘珊瑚礁的研究都集中在大堡礁和加勒比地区的当代（在少数情况下是历史）评估。需要来自不同地区的新数据集来捕捉现代人类的全面影响（特别是在珊瑚发展最多样化的地区），我们还需要跨越时间尺度（数百年至数千年）的数据，以捕捉珊瑚生态适应和边缘环境中的迁移。在这种情况下，最近发现的异常保存化石的珊瑚三角区（CT）地区的东南亚提供了一个独特的机会，整合当今的生态数据与信息的地质记录，以记录浊水珊瑚礁的进化和生态历史在现代的全球生物多样性热点。有迫切需要更多的信息的多样性，结构和功能的边缘珊瑚礁在CT，以帮助制定管理策略，他们继续应对人类的影响。因此，我们的研究的长期时间范围是显着的。越来越多的研究旨在描述潜在的现今珊瑚礁避难所的组成、分布和遗传结构，我们将把化石记录中的数据添加到这些分析中。有一个令人信服的理由这样做，因为珊瑚礁的复原力很可能是由长期的过程，在进化历史中有着深刻的根源。我们将评估的双重作用的边缘珊瑚礁在CT的摇篮和避难所的多样性。主要研究问题包括：1）边缘生态系统的珊瑚多样性是否随时间而变化？2)珊瑚礁群落如何应对区域或全球范围的环境变化？3)珊瑚礁在边缘环境中的功能发生了怎样的变化，对与珊瑚礁有关的生物区系产生了什么后果？4)在生物多样性热点的演变过程中，珊瑚礁从边缘珊瑚礁迁移到清水珊瑚礁有多容易？5）如果清水栖息地变得越来越不适合居住，对现代生物群会有什么后果？为了解决这些问题，我们将产生新的全面的数据集的物种出现，丰度，形态特征，生态数据和环境，覆盖30万年的珊瑚礁的历史的CT。有了这些资源，我们将通过将分子系统学，地球化学和进化模式的新工具应用于现代珊瑚礁和广泛且采样良好的化石记录，为长期争论的问题提供严格的答案。最终，我们将能够揭示CT中边缘珊瑚礁的黑暗历史，并更好地了解CT中珊瑚礁和其他依赖珊瑚礁经济和生态价值的地区未来珊瑚礁的潜在变化轨迹。

Coral reefs are the most diverse marine ecosystems on Earth and provide enormous economic value for hundreds of millions of people including fisheries, tourism, and coastal protection. However, these benefits are threatened by the rapid decline of coral reefs resulting from accelerating human impacts on local to global scales. Confronting this reef crisis with limited resources requires prioritisation of protection actions, and many researchers are now turning to reef ecosystems living outside of typical shallow, clear-water habitats as critical priorities for additional research. There is new evidence that these so-called marginal reefs living in turbid or deeper water can be more resilient to bleaching, changes in water quality, and other impacts. Increased bleaching resilience might result from sediments in the water that limit UV stress, or because the corals may be more readily able to take advantage of food sources in the plankton. Thus, marginal reefs potentially serve as refugia for resilient corals, and could be critical for the future recovery of declining clear-water reefs. However, most studies of marginal reefs have focused on contemporary (and in a few cases historical) assessments from sites on the Great Barrier Reef (GBR) and the Caribbean. New datasets from different regions are needed to capture the full range of modern human impacts (especially in areas of the most diverse coral development), and we also need data that spans the timescales (centuries to millennia) necessary to capture coral ecological adaptation and migration within marginal settings. In this context, recent discoveries of exceptionally preserved fossils from the Coral Triangle (CT) region of Southeast Asia provide a unique opportunity to integrate present-day ecological data with information from the geological record to document the evolutionary and ecological history of turbid water reefs in the modern-day global biodiversity hotspot. There is an urgent need for more information on the diversity, structure, and functioning of marginal reefs in the CT in order to help develop management strategies they continue to respond to human impacts.The long-term temporal scope of our study is thus significant. A growing body of research aims to describe the composition, distribution, and genetic structure of potential present-day reef refugia and we will add data from the fossil record into these analyses. There is a compelling case to do this because reef resilience is likely to be shaped by long-term processes with deep roots in evolutionary history. We will assess the dual role of marginal reefs in the CT as both cradles and refugia of diversity. Key research questions include: 1) has coral diversity of marginal ecosystems changed through time? 2) how have reef communities responded to environmental changes on regional or global scales? 3) how has reef functioning in marginal settings changed and what have been the consequences for reef-associated biota? 4) how easy has it been for reef-corals to move from marginal to clear-water reefs during the evolution of the biodiversity hotspot, and 5) what could be the consequences for the modern biota if clear water habitats become increasingly inhospitable?To address these questions we will produce new comprehensive datasets of species occurrences, abundances, morphological traits, ecological data, and environments that cover 30 million years of reef history of the CT. With this resource, we will provide rigorous answers to long-debated issues by applying new tools for molecular systematics, geochemistry, and evolutionary patterns to modern reefs and an extensive and well-sampled fossil record. Ultimately, we will be able to reveal the murky history of marginal reefs in the CT and better understand the potential future trajectories of change for coral reefs in the CT and in other regions that depend on coral reefs for their economic and ecological value.