EAGER: A Saturation Approach to Microzooplankton Grazing Rate Determination

异养原生生物是全球50%的海洋浮游植物初级产品的主要消费者。因此，它们在影响海洋生物地球化学、微生物群落组成和向更高营养水平的能量转移方面发挥着关键作用。该项目的目的是开发一种新的饱和度方法来量化海洋中吞噬原生生物对浮游植物的放牧率。作为一项概念验证，本研究将侧重于确定浮游植物的放牧率。这种最小的浮游植物通常在海洋初级生产中占主导地位，可占沿海水域年初级生产的50%。了解放牧对于了解浮游生物群落如何发挥作用并对环境变化做出反应至关重要，它具有重要的社会效益，可以更准确地预测全球渔业的未来以及影响我们气候的海洋和大气之间的相互作用。该项目结合了本科生在研究环境和生物海洋学方面的体验式教育，并将成为为研究生、教师和商业实体设计的高级水生流动课程的一个特色。公众对科学的参与将通过Cafe Scientifique的演讲和毕格罗实验室全年举行的一系列开放日活动进行。这个项目背后的动机是，在执行和解释当前海洋原生生物食草性实验测量方面的挑战限制了我们对这一关键过程的理解。目前方法的基础是放牧动物与替代猎物的饱和，导致释放放牧对自然猎物的压力。测量由此产生的自然猎物的生长率，可以为放牧率提供一个值。该项目包括实验室实验，使用模型捕食者-猎物组合的培养来选择合适的替代猎物，并测试该方法的潜在理论假设。然后，这些信息将被用来为自然浮游生物群落的实验设计提供信息。这些实验的目的是测试饱和方法的有效性，并将结果与并行运行的传统实验方法进行比较。这项研究将引入一种新的生物海洋学方法，该方法将经过彻底的测试，并对最佳设置程序提出建议，并对影响结果不确定性的因素进行评估。与以前的方法相比，饱和方法具有潜在的优势。它适合流式细胞术分析，允许高通量和精确测量，避免对天然海水和微生物群落的操纵，并提供浮游植物群落定义成分的生长和放牧信息。

Heterotrophic protists are the dominant consumers of the 50% of global primary production by phytoplankton in the oceans. Hence, they play a key role in influencing ocean biogeochemistry, the composition of microbial communities, and transfer of energy to higher trophic levels. The aim of the project is to develop a novel saturation approach to quantify the rates of grazing on phytoplankton by phagotrophic protists in the ocean. As a proof-of-concept, this study will focus on determining grazing rates on picophytoplankton. This smallest size-class of phytoplankton often dominates oceanic primary production and can contribute up to 50% of annual primary production in coastal waters. Understanding grazing is of critical importance to understanding how planktonic communities function and respond to environmental change has the important societal benefit of potentially more accurately predicting the future of global fisheries and interactions between ocean and atmosphere that influence our climate. The project incorporates experiential education of undergraduates in the research environment and biological oceanography and will be a feature of an Advanced Aquatic Flow Courses designed for graduate students, faculty members and commercial entities. Public engagement in the science will be through Cafe Scientifique presentations and the series of Open House events that occur at Bigelow Laboratory through the year.The motivation behind this project is that challenges in performing and interpreting current experimental measurements of herbivory by protists in the ocean constrain our understanding of this key process. The basis of the present approach is saturation of the grazers with a surrogate prey, resulting in release of grazing pressure on the natural prey. Measurement of the resulting increased growth rate of the natural prey provides a value for the rate of grazing. The project involves laboratory experiments using cultures of model predator-prey combinations to select suitable surrogate prey and test the underlying theoretical assumptions of the approach. This information will then be used to inform the design of experiments on natural planktonic communities. The objectives of these experiments are to test the efficacy of the saturation approach and to compare results to traditional experimental approaches run in parallel. This research will introduce a new approach to biological oceanography that will have been thoroughly tested, with recommendations for optimum set-up procedures and an assessment of the factors that influence uncertainty in the results. The saturation approach has potential advantages over previous methods. It lends itself to analysis by flow cytometry allowing high throughput and accurate measurements, avoids manipulation of the natural seawater and microbial communities, and provides growth and grazing information on defined components of the phytoplankton community.