EAGER: A Saturation Approach to Microzooplankton Grazing Rate Determination

异养原生生物是全球海洋浮游植物初级生产量的50%的主要消费者。因此，它们在影响海洋生物地球化学、微生物群落组成和能量向更高营养水平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方法来量化海洋中摄食性原生生物对浮游植物的捕食率。作为概念验证，这项研究将集中于确定对微藻浮游植物的捕食率。这种最小体型的浮游植物通常在海洋初级生产量中占据主导地位，可以贡献沿海水域年初级生产量的50%。了解放牧对于了解浮游生物群落如何运作和应对环境变化至关重要，这对更准确地预测全球渔业的未来以及影响我们气候的海洋与大气之间的相互作用具有重要的社会益处。该项目结合了本科生在研究环境和生物海洋学方面的经验教育，并将成为为研究生、教职员工和商业实体设计的高级水上流动课程的一个特色。公众对科学的参与将通过Cafe Science演示和毕格罗实验室全年举行的一系列开放参观活动来进行。该项目背后的动机是，在执行和解释海洋原生生物目前对食草动物的实验测量方面的挑战限制了我们对这一关键过程的理解。这种方法的基础是捕食者与代理猎物饱和，导致对自然猎物的放牧压力的释放。对自然猎物因此而增加的增长率的测量提供了放牧率的值。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代理猎物，并测试该方法的基本理论假设。然后，这些信息将被用于设计关于天然浮游生物群落的实验。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。这项研究将介绍一种新的生物海洋学方法，该方法将经过彻底测试，并就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。它有助于通过流式细胞术进行分析，允许高通量和准确的测量，避免对自然海水和微生物群落的操纵，并提供关于浮游植物群落的特定组成部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.