Collaborative Research: The effects of diatom-produced polyunsaturated aldehydes on the microbial food wed in temperate and polar waters

概述：该项目将进行一系列现场/实验室实验，以解决以下关于微型浮游动物（20-200 µm之间的消费者）和硅藻产生的多不饱和醛的假设：I。醛类会损害微型浮游动物对硅藻和非硅藻浮游植物的植食性。 二.醛类会降低微型浮游动物和不产生PUA的浮游植物的生长速率。 三.在存在产藻硅藻的情况下，桡足类将转变为微型浮游动物，而无毒（轻度）硅藻将成为桡足类的重要食物来源。 四.醛类对微型浮游动物和桡足类的影响将取决于食草动物事先暴露于普阿。实验将包括天然浮游生物、捕获的桡足类、培养的海洋短丝藻（SM），包括其产多糖菌株和合成醛。为了深入了解复杂的相互作用，在它们的组成，丰度和动态的详细信息，将获得使用显微镜，流式细胞术和细胞学方法。这种方法将使PI得出结论的作用，植物浮游生物-微型浮游动物-桡足类营养相互作用的醛类化合物。研究所将与设在Anton Dohrn动物学站（意大利那不勒斯）的普阿研究小组协调工作并交换信息。最近的证据表明，微型浮游动物是主要的食草动物，而桡足类往往依赖于微型浮游动物作为食物，除了在高峰期硅藻生产。微型浮游动物以大型硅藻为食，并与其藻类猎物一样快速生长的能力导致了一个问题：是什么让硅藻在其开花的初始阶段逃脱微型浮游动物的放牧控制，并保持开花，直到营养资源耗尽？化感作用广泛存在于浮游植物中。世界性水华形成SM产生几种醛，并已成为浮游生物化感作用研究的模式生物。大多数关于硅藻细胞毒性的研究都致力于对海洋无脊椎动物繁殖和发育的抑制作用，而令人惊讶的是，关于其对关键硅藻食草动物微型浮游动物的影响的信息很少。在切萨皮克湾的初步研究结果表明，醛类可能会引起级联效应的水生群落。拟议的研究将：（1）增进我们对沿海海洋中浮游生物-微型浮游动物-桡足类之间关键联系的了解;（2）生成关于化感作用对海洋食物网影响的新数据;（3）通过比较大西洋温带沃茨的浮游生物结构和动态，促进我们对更广泛的海洋生态系统模式的理解;（4）通过国际合作推进生物海洋学。阿克伦大学和马里兰州大学的一名博士后研究员、两名研究生和几名本科生将接受这一项目的培训。该项目将吸引积极的少数民族学生参加该计划。该研究将通过与WVIZ Ideastream网络合作的互动式远程学习系列扩展到7-12年级的学生和教师。PI将继续与五大湖科学中心建立现有的外展伙伴关系，该中心最近发布了一份关于北极变化和NSF赞助研究的电子报告。四万五千人。PI还将与克利夫兰自然历史博物馆合作开发公共项目，并与国家发明家名人堂STEM中学合作开发以极地研究为重点的课程。课程模块将可从一个专门的网站免费下载。 更广泛的影响，有限责任公司，将评估这些教育和推广活动。

Overview: This project will conduct a set of field/laboratory experiments to address the following hypotheses with respect to microzooplankton (consumers between 20-200 µm) and diatom- produced polyunsaturated aldehydes: I. Aldehydes will impair microzooplankton herbivory on diatoms and non-diatom phytoplankton. II. Aldehydes will reduce the growth rates of microzooplankton and non PUA-producing phytoplankton. III. In the presence of aldehyde-producing diatoms, copepods will switch to microzooplankton, whereas non- (mildly)- toxic diatoms will be an important food source for copepods. IV. The effects of aldehydes on microzooplankton and copepods will depend on the grazers' prior exposure to PUA. The experiments will include natural plankton, captured copepods, cultured Skeletonema marinoi (SM), including its aldehyde-producing strain, and synthetic aldehydes. To gain insights into complex interactions within planktonic communities, detailed information on their composition, abundance, and dynamics will be obtained using microscopy, flow-cytometry, and cytological methods. This approach will allow the PIs to draw conclusions about the role of diatom-produced aldehydes in phytoplankton-microzooplankton- copepod trophic interactions. The PIs will coordinate efforts and exchange information with the PUA study group at the Stazione Zoologica Anton Dohrn (Naples, Italy).Intellectual merit: Diatoms are dominant autotrophic plankton in the ocean. Recent evidence indicates that microzooplankton are the dominant herbivores, whereas copepods often rely on microzooplankton as food, except during peak diatom production. The ability of microzooplankton to feed on large diatoms and grow as fast as their algal prey leads to the question of what allows diatoms to escape microzooplankton grazing control during the initial phases of their blooms and maintain the blooms until nutrient resources are depleted? Allelopathy is wide spread among phytoplankton. The cosmopolitan bloom-forming SM produces several aldehydes and has become a model organism in plankton allelopathy studies. Most studies on diatom cytotoxicity have been dedicated to inhibitory effects on reproduction and development of marine invertebrates, whereas surprisingly little information exists on its impact on key diatom grazers, microzooplankton. Preliminary results in the Chesapeake Bay show that aldehydes may induce cascading effects within planktonic communities. The proposed study will: (1) Improve our knowledge of the critical diatom-microzooplankton-copepod links in the coastal ocean; (2) Generate novel data on the effects of allelopathy on marine food webs; (3) Contribute to our understanding of broader patterns of marine ecosystems by comparing plankton structure and dynamics in the temperate Atlantic waters; (4) Advance biological oceanography through international collaboration.Broader Impacts: One post-doctoral fellow, two graduate students and several undergraduate students at the Universities of Akron and Maryland will be trained as a result of this project. The project will attract motivated minority students into the program. The research will be extended to students in grades 7-12 and teachers via an interactive distance learning series in collaboration with the WVIZ Ideastream network. The PIs will continue an existing outreach partnership with the Great Lakes Science Center, where a recent electronic presentation dedicated to Arctic change and NSF-sponsored research was seen by ca. 45,000 visitors. The PIs will also work with the Cleveland Museum of Natural History to develop public programs, and with the National Inventors Hall of Fame STEM Middle School to develop a curriculum focused on polar research. Curriculum modules will be available as free downloads from a dedicated website. Broader Impacts, LLC, will evaluate these education and outreach activities.