Biogeochemical and Ecological Impacts of Amphipod Circoviruses in Benthic Habitats

概述：这个项目将通过研究病毒流行的实验梯度和添加培养的病毒来调查圆环病毒如何影响底栖两足动物的食草性/破坏性比率。需要检验的假设是：H1：圆环病毒导致受感染的片足类宿主的危害和食草性减少；H2：圆环病毒对两足类动物的影响导致沉积物细菌的生长速度下降，沉积物微生物的胞外纤维素酶活性降低，沉积物中氧化的无机营养物质进入上覆水域的通量减少；H3：圆环病毒对宿主的营养质量产生负面影响。这些假说将通过进行沉积物-水中围隔实验来验证，以评估圆环病毒对水生植被破坏的影响，以及随后对生物地球化学的影响，包括细菌产生、还原态氮向上覆水域的流出和溶解有机碳的产生。最后，本项目将通过检测环状病毒流行程度高到低的片足类种群和实验感染的两足类群的元素比率来研究圆环病毒如何影响两足类的营养质量。来自这三种方法的数据将被用来形成一个模型，说明圆环病毒如何影响底栖生物食物网和沉积物栖息地的生物地球化学循环。这项研究集中在两种对生态系统功能至关重要的生态敏感的两足动物中的圆环病毒：Diporeia(在密歇根湖)，它的丰度在过去20年里在五大湖内经历了急剧下降，以及全食人猿，它是美国西海岸受到环境威胁的巨型海藻Macrocystis pyrifera的主要消费者。智力价值：几十年的研究已经确定了病毒在水生态和生物地球化学中的重要性。然而，大多数研究都集中在真核微生物的噬菌体和病毒上。后生动物是底栖生物地球化学的重要驱动因素，它们导致缺氧沉积物的生物灌溉、再悬浮、颗粒物质的沉降，促进从沉积物到上覆水域的营养通量，并可能影响沉积物反硝化等海洋规模的过程。圆环病毒是甲壳类病毒的常见组成部分，与寄主死亡率和种群数量下降密切相关，而培养的圆环病毒可导致节肢动物细胞死亡。因此，迫切需要调查病毒如何影响其甲壳类宿主的生态，以及这些影响又如何影响生态系统功能。两足类是底栖生境的重要表层动物成分，在那里它们消耗固定的颗粒物和水生植被，这反过来又通过微生物降解影响其向溶解有机物的转化。反过来，它们的摄食活动刺激海底矿化率，它们被更高的营养水平消耗。因此，两足类动物将微生物与沿海和湖泊栖息地的大型食物网联系起来。作为后生动物病毒如何影响水生生态系统生物地球化学的模型，该项目调查了感染两足类动物的圆环病毒如何通过底栖生态系统影响碳的通量。这项研究将深入了解病毒如何影响水生生物地球化学，开辟底栖生态系统后生动物病毒研究的新领域。广泛影响：该项目旨在纳入三项更广泛的影响活动。首先，它将让纽菲尔德高中(Newfield，NY)和Oneida Lake地区高中的科学教师直接参与并将高需求学生纳入研究团队，进行实验和实验室分析，最终向他们的同龄人介绍他们的研究活动。其次，它将通过在康奈尔生物野外站的暑期实习吸引本科生，并在学年期间邀请康奈尔的本科生研究人员参与实验，磨练科学陈述的技能。第三，它将开发广泛的基于网络的推广工具，包括一个网站(包含实验的现场观察)，以及针对普通公众和K-12学生的社交媒体页面。最后，拟议的工作将提供对脆弱的水生生态系统的生态的洞察。

Overview: This project will investigate how circoviruses influence the herbivory/detritivory rates of benthic amphipods through the study of an experimental gradient of viral prevalence and by addition of cultivated viruses. The hypotheses to be tested are: H1: Circoviruses cause decreased detritivory and herbivory by infected amphipod hosts; H2: Circoviral impacts on amphipods result in decreased growth rate of sediment bacteria, decreased extracellular cellulose activity of sediment microorganisms, and decreased fluxes of oxidized inorganic nutrients from sediments into overlying waters; H3: Circoviruses negatively impact the nutritional quality of their hosts. These hypotheses will be tested by conducting sediment-water mesocosm experiments to assess the impacts of circoviruses on aquatic vegetation breakdown, and subsequent impacts on biogeochemistry, including bacterial production, efflux of reduced N into overlying waters, and production of dissolved organic C. Finally, this project will examine how circoviruses influence the nutritional quality of amphipods by examining elemental ratios of amphipod populations from high to low circoviral prevalence and experimentally infected amphipods. Data from these three approaches will be used to form a model of how circoviruses influence benthic foodwebs and biogeochemical cycles in sediment habitats. This study focuses on circoviruses within two ecologically sensitive amphipods that are crucial to ecosystem function: Diporeia (in Lake Michigan), which has experienced dramatic decline in abundance over the last 20 years within the Great Lakes, and Peramphithoe femorata, which is a major consumer of the environmentally threatened giant kelp Macrocystis pyrifera on the US West Coast.Intellectual Merit: Decades of research have identified the importance of viruses in aquatic ecology and biogeochemistry.However, most studies have focused on bacteriophage and viruses of eukaryotic microorganisms. Metazoa are important drivers of benthic biogeochemistry, where they cause bioirrigation of anoxic sediments, resuspension, settlement of particulate matter, facilitating nutrient fluxes from sediments to overlying waters, and potentially influencing ocean-scale processes like sediment denitrification. Circoviruses have been identified as a common constituent of crustacean viral assemblages, where they are well correlated with host death rates and population decline, and cultivated circoviruses cause death of arthropod cells. There is therefore a strong need to investigate how viruses impact the ecology of their crustacean hosts, and how in turn those impacts influence ecosystem function. Amphipods are important epifaunal constituents of benthic habitats, where they consume settled particulate matter and aquatic vegetation, which in turn influences its conversion to dissolved organic matter through microbial degradation. In turn their feeding activities stimulate benthic mineralization rates, and they are consumed by higher trophic levels. Therefore, amphipods link microbial to macrobial food webs in coastal and lake habitats. This project investigates how circoviruses infecting amphipods influence the flux of C through benthic ecosystems as a model of how viruses of metazoa influence biogeochemistry of aquatic ecosystems. The research will provide insight into how viruses influence aquatic biogeochemistry, opening up a new area of research into metazoan viruses in benthic ecosystems.Broader Impacts: The project has been designed to incorporate three broader impact activities. First, it will involve science teachers at the Newfield High School (Newfield, NY) and Oneida Lake Region high schools to directly involve and integrate high needs students into the research team to conduct experiments and laboratory analyses, culminating in presentation of their research activities to their peer group. Second, it will engage undergraduate students through summer internships at the Cornell Biological Field Station, and undergraduate researchers during the school year at Cornell to participate in the experiments and hone skills in scientific presentation. Third, it will develop extensive web-based outreach tools, including a website (incorporating live views of experiments), and social media pages targeting the general public and K-12 students. Finally, the proposed work will provide insight into the ecology of vulnerable aquatic ecosystems.