Collaborative Research: Viral Reefscapes: The Role of Viruses in Coral Reef Health, Disease, and Biogeochemical Cycling

从生态和经济上讲，珊瑚礁是地球上最有价值的生态系统之一。据估计，这些栖息地拥有多达900万个物种，每年为全球经济贡献约300亿美元，是生物地球化学循环的热带震中。全球(气候变化)和局部(营养物质污染和过度捕捞)压力是珊瑚礁衰退的驱动因素，珊瑚礁衰退可能破坏珊瑚和栖息微生物群落之间的共生关系，包括甲藻、细菌和病毒。病毒与所有活的细胞生物相互作用，在海洋中大量存在，是海洋生态系统功能不可或缺的组成部分。该项目将首次量化不同珊瑚礁栖息地和不同时间珊瑚中病毒感染的变异性。这将增加我们对珊瑚病毒总体多样性的了解，并阐明在珊瑚礁上引发病毒爆发的一整套因素。与此同时，该项目将评估全球和局部压力如何改变珊瑚礁上的碳和氮循环，从而引发病毒感染。这个项目最终将扩大我们对病毒对珊瑚礁的影响的理解，而不仅仅是它们作为假定的疾病病原体的作用。该项目的成果将在科学领域、K-12、本科生和研究生教育和培训方案中广泛传播，并通过视频和多媒体制作以及外联活动向公众广泛传播。我们将建造我们在莫雷亚的现场的2-D珊瑚礁复制品，使美国和法属波利尼西亚的儿童和成年人能够成为海洋科学家，并使用样机、横断面磁带和识别指南来量化珊瑚礁变化的指标。三名研究生将参与研究的方方面面，并将努力招收和支持少数民族学生。所有数据集将免费向公众提供，该项目新开发的方法将作为一套重要的跳板工具和基线，用于未来对影响珊瑚礁健康的过程进行调查。珊瑚礁发现于营养不良的浅水水域，是生物多样性和生产力热点，提供了大量的生态和社会效益。珊瑚通过向周围的海水释放大量的粘液(一种富含有机碳和氮的基质)来大力补贴这些营养不足的生态系统。珊瑚礁水域的病毒产生可能是珊瑚礁碳循环的重要组成部分，约占珊瑚礁生态系统底栖生物碳固定总量的10%。珊瑚表面的病毒也比水柱中的病毒多约10倍，这意味着珊瑚在应激期间经历的病毒感染可能会导致进入水柱的碳和氮通量增加。因此，噬菌体和真核病毒可能通过珊瑚和共生体感染直接改变珊瑚礁的健康和功能，并通过改变宿主群体和邻近珊瑚礁系统的生物地球化学循环。该项目的主要目标是对病毒感染、珊瑚和珊瑚礁健康下降以及珊瑚礁生态系统中生物地球化学循环的相关变化之间的联系进行实验研究并建立模型。将在莫雷亚珊瑚礁LTER进行实验室和现场实验，以确定两种主要造礁珊瑚物种内病毒的时空动态，这两种珊瑚物种对非生物压力的敏感性不同。一种新的病毒感染和诱导方法将与稳定同位素脉冲追逐实验相结合，以量化和跟踪从珊瑚全生物(宿主和微生物共生体)到溶解和颗粒物池的碳和氮通量。在这些实验中，病毒、细菌和共生体的丰度、多样性和功能将与宿主的健康和活动同时进行测量。脉冲追逐技术以及基于通量和生态位的建模将导致对珊瑚和相关病毒如何影响珊瑚礁能量收支以及碳和氮通量对珊瑚礁群落的影响的全面了解。最终，该项目将量化和描述环境应激源改变病毒、微生物和珊瑚多样性从而改变生态系统功能的综合机制。

Ecologically and economically, coral reefs are among the most valuable ecosystems on Earth. These habitats are estimated to harbor up to nine million species, contribute ~30 billion US dollars annually to the global economy, and are tropical epicenters of biogeochemical cycling. Global (climate change) and local (nutrient pollution and overfishing) stressors are drivers of coral reef decline that can disrupt the symbiotic associations among corals and resident microbial communities, including dinoflagellate algae, bacteria, and viruses. Viruses interact with all living cellular organisms, are abundant in oceans, and integral to marine ecosystem functioning. This project will be the first to quantify the variability of viral infection in corals across different reef habitats and across time. This will increase our understanding of the total diversity of coral viruses and illuminate the full suite of factors that trigger viral outbreaks on reefs. At the same time the project will evaluate how carbon and nitrogen cycling are altered on coral reefs as a result of global and local stressors that trigger viral infection. This project will ultimately broaden our understanding of the impacts of viruses on reefs beyond their role as putative disease agents. Results of the project will be communicated broadly in scientific arenas, in K-12, undergraduate, and graduate education and training programs, and to the general public through video and multimedia productions, as well as outreach events. 2-D Reef Replicas from our field sites across Moorea will be constructed, allowing children and adults in the US and French Polynesia to 'become' marine scientists and use quadrats, transect tapes, and identification guides to quantify metrics of reef change. Three graduate students will be involved in all aspects of the research and an effort will be made to recruit and support minority students. All datasets will be made freely available to the public and newly developed methods from this project will serve as an important set of springboard tools and baselines for future lines of inquiry into the processes that influence reef health. Coral reefs, found in nutrient-poor shallow waters, are biodiversity and productivity hotspots that provide substantial ecological and societal benefits. Corals energetically subsidize these oligotrophic ecosystems by releasing significant amounts of mucus (an organic carbon and nitrogen-rich matrix) into the surrounding seawater. Viral production in reef waters can be a significant portion of total reef carbon cycling, accounting for ~10% of gross benthic carbon fixation in reef ecosystems. Viruses are also ~10 times more abundant on coral surfaces than in the water column meaning that viral infection experienced by corals during stress likely results is an increase in carbon and perhaps nitrogen flux to the water column. Thus phages and eukaryotic viruses may be responsible for shifting reef health and function directly via coral and symbiont infection and by altering biogeochemical cycling in host colonies and the adjacent reef system. The main goal of this project is to experimentally interrogate and then model the links among viral infections, declines in coral and reef health, and associated shifts in biogeochemical cycling in reef ecosystems. Lab and field experiments will be conducted at the Moorea Coral Reef LTER to characterize the spatiotemporal dynamics of viruses within two dominant reef-building coral species that differ in their susceptibility to abiotic stress. A novel viral infection and induction approach will be coupled with stable isotopic pulse-chase experiments to quantify and track carbon and nitrogen flux out of coral holobionts (host and microbial symbionts) and into dissolved and particulate pools. In these experiments, virus, bacteria, and symbiont abundance, diversity, and function will be measured simultaneously with the health and activity of the host. Pulse-chase techniques, as well as flux- and niche-based modeling, will result in a holistic understanding of how corals and associated viruses impact reef energy budgets and the ramifications of carbon and nitrogen flux for reef communities. Ultimately, this project will quantify and describe an integrated mechanism by which environmental stressors alter viral, microbial, and coral diversity and, consequently, ecosystem function.