Biodiversity and Complex Forcing of Ecosystem Functioning in the Marine Foundation Species, Eelgrass: A Global Experimental Network

知识价值。该项目将建立一个全球野外实验合作网络，量化资源和放牧如何沿着生物多样性和非生物强迫的自然梯度相互影响生物量、产量和营养转移。它侧重于无脊椎中食草动物与全球分布的大叶藻（Zostera marina）之间的关键互惠关系，作为一种模式系统和全球重要但受到威胁的沿海生态系统的基础。这种相互作用为将生物多样性与多营养生态系统的功能（BEF）联系起来的有影响力的实验提供了模型。然而，从历史上看，海草生态学几乎只关注自下而上的作用力，而这些无处不在的动物在野外的影响几乎是未知的。该研究计划将解决三个问题：(1)甲壳类中食草动物（相当于放牧桡足类的底栖动物）在调节植被覆盖的沿海生态系统功能和缓冲富营养化作用中发挥什么作用？(2)从15年的BEF实验中得出的结论是否与复杂开放海洋系统中生态系统特性沿自然多样性梯度的变化相一致？(3)资源供应、放牧压力和生物多样性对生态过程的相对影响和相互作用是否随气候和非生物环境驱动因素而系统变化？方法将包括两种新的方法。首先，一项新的技术排除了没有笼子人工制品的甲壳类中食草动物，将严格测试它们长期以来被怀疑在培养大型植物优势方面的作用。该项目汇集了经验丰富的合作者，他们将在横跨亚全球范围的12个地点进行相同的因子实验，操纵食草动物和营养负荷，跨越多样性和非生物强迫变量的相关梯度。其次，结构方程模型（SEM）专门用于量化复杂系统中变量之间的相对重要性和相互作用，将梳理出资源供应、食草动物生物量、物种组成和丰富度以及一些非生物变量对大叶藻和藻类生物量、生产和营养转移的影响。对合成群落进行的小规模实验表明，生物多样性通常会促进一系列生态系统的生产和资源利用，但相对于其他有充分记录的强迫因子，多样性的重要性仍然知之甚少。有趣的是，在野生生态系统的少数研究中，BEF关系往往饱和于比实验高得多的丰富度，这表明先前的工作可能低估了而不是高估了多样性的功能效应。然而，很少有大规模的数据集可用于评估这一猜想。这项研究将在全球范围内的鳗草床上进行，这是少数几个可能进行此类测试的群落类型之一。更广泛的影响。该项目将启动一个持久的、开放的、研究人员合作的网络，研究多营养海洋植被生态系统的功能。它利用了全球分布的合作者的专业知识、人力和跨国伙伴关系的经验，包括由澳大利亚研究委员会资助的海洋植物-草食生态学家的新网络；海洋生物普查NaGISA项目；以及MarBEF BIOFUSE项目的主要合作伙伴。因此，它将促进若干以前独立的研究工作的整合。该项目还将通过学生交换计划帮助建立下一代合作的海洋植被生态学家：来自每个合作地点的学生将在另一个地点充分参与实验，提供新系统的实地经验，并培养与新同事的关系，这种关系将在该奖项的任期届满后持续很长时间。学生将从现有的Hall- Bonner海洋科学少数民族博士学者项目（VIMS是该项目的合作伙伴）和其他几个培养海洋科学中代表性不足群体的当地项目中招募。

Intellectual Merit. This project will develop a global collaborative network of field experiments to quantify how resources and grazing interactively affect biomass, production, and trophic transfer along natural gradients in biodiversity and abiotic forcing. It focuses on a key mutualism between invertebrate mesograzers and the globally distributed eelgrass (Zostera marina), as a model system and as the foundation of important but threatened coastal ecosystems worldwide. This interaction provided a model for influential experiments linking biodiversity to functioning (BEF) of multitrophic ecosystems. Yet, seagrass ecology has historically focused almost exclusively on bottom-up forcing, and impacts of these ubiquitous animals in the field are nearly unknown.The research program will address three questions: (1) What role do crustacean mesograzers, the benthic equivalents of grazing copepods, play in regulating vegetated coastal ecosystem functioning and buffering effects of eutrophication? (2) Are generalizations derived from 15 years of BEF experiments consistent with variation in ecosystem properties along natural diversity gradients in complex, open marine systems? (3) Do relative influences and interactions of resource supply, grazing pressure, and biodiversity on ecological processes vary systematically with climate and abiotic environmental drivers? Methods will include two novel approaches. First, a new technique that excludes crustacean mesograzers without cage artifacts will rigorously test their long-suspected role in fostering macrophyte dominance. The project assembles experienced collaborators who will conduct identical factorial experiments manipulating grazers and nutrient loading at each of 12 sites spanning the sub-global range of eelgrass, across concomitant gradients in diversity and abiotic forcing variables. Second, Structural Equation Models (SEM), designed specifically to quantify relative importance and interactions among variables in complex systems, will tease apart effects of resource supply, grazer biomass, species composition, and richness, and several abiotic variables on eelgrass and algal biomass, production, and trophic transfer. Small-scale experiments with synthesized communities show that biodiversity generally enhances production and resource use in a range of ecosystems, but the importance of diversity relative to other well-documented forcing factors remains poorly understood. Intriguingly, BEF relationships in the few studies from wild ecosystems often saturate at much higher richness than in experiments, suggesting that prior work may underestimate rather than overestimate functional effects of diversity. Yet few large-scale data sets are available to evaluate this conjecture. This research will do so on a global scale in eelgrass beds, one of the few community types in which such a test is possible.Broader Impacts. This project will initiate a lasting, and open, collaborative network of researchers studying the functioning of multitrophic marine vegetation ecosystems. It leverages a wealth of globally distributed collaborator expertise, person power, and experience with multinational partnerships including a new network of marine plant-herbivore ecologists funded by the Australian Research Council; the Census of Marine Life's NaGISA project; and key partners in MarBEF's BIOFUSE project. It will thus catalyze integration of several formerly independent research efforts. The project will also help establish the next generation of collaborative marine vegetation ecologists through a student exchange program: students from each partner site will participate fully in the experiment at one of the other sites, providing field experience in new systems, and fostering relationships with new colleagues lasting well beyond the tenure of this award. Students will be recruited from the existing Hall- Bonner Program for Minority Doctoral Scholars in Ocean Sciences, of which VIMS is a partner, and from several other local programs that train underrepresented groups in marine science.