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

概述：本项目将进行一系列现场/实验室实验，以解决关于微型浮游动物(消费在20-200微米之间)和硅藻产生的多不饱和醛的以下假设：i.醛将损害微型浮游动物对硅藻和非硅藻浮游植物的食草性。二、醛会降低微型浮游动物和不产生PUA的浮游植物的生长速度。在产醛硅藻存在的情况下，桡足类将转变为微型浮游动物，而非(温和)毒性的硅藻将成为桡足类的重要食物来源。醛对微型浮游动物和桡足类动物的影响将取决于食草动物先前接触PUA的情况。这些实验将包括天然浮游生物、捕获的桡足类动物、养殖的Marinoi骨骼藻(SM)，包括它的产醛菌株，以及合成醛。为了深入了解浮游生物群落内部的复杂相互作用，将使用显微镜、流式细胞术和细胞学方法获得关于它们的组成、丰度和动力学的详细信息。这一方法将使PI能够就硅藻产生的醛在浮游植物-微型浮游动物-桡足类营养相互作用中的作用得出结论。PIS将与意大利那不勒斯Stazione Zoologica Anton Dohrn的PUA研究小组协调努力并交换信息。智力优势：硅藻是海洋中主要的自养浮游生物。最近的证据表明，微型浮游动物是主要的草食动物，而桡足类通常以微型浮游动物为食物，除非在硅藻生产的高峰期。微型浮游动物以大型硅藻为食，并像它们的猎物藻类一样快速生长的能力引发了这样一个问题：是什么允许硅藻在水华爆发的最初阶段逃脱微型浮游动物的捕食控制，并保持水华直到营养资源耗尽？化感作用在浮游植物中广泛存在。这种世界性的水华形成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抑制海洋无脊椎动物的繁殖和发育，而令人惊讶的是，关于它对关键的硅藻食草动物-微型浮游动物的影响的信息很少。切萨皮克湾的初步结果表明，醛可能会在浮游生物群落中引发级联效应。拟议的研究将：(1)提高我们对沿海海洋中关键的硅藻-微型浮游动物-桡足类动物联系的知识；(2)产生化感作用对海洋食物网的影响的新数据；(3)通过比较温带大西洋水域的浮游生物结构和动态，有助于我们了解更广泛的海洋生态系统模式；(4)通过国际合作促进生物海洋学。该项目将吸引有积极性的少数族裔学生加入该项目。这项研究将通过与WVIZ IDEADESTREAM网络合作的互动远程学习系列扩展到7-12年级的学生和教师。PIS将继续与五大湖科学中心建立现有的外联伙伴关系，在那里，大约45,000名参观者观看了最近一次致力于北极变化和国家科学基金会赞助的研究的电子演示。PIS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中学合作开发专注于极地研究的课程。课程模块将从一个专门的网站上免费下载。更广泛的影响有限责任公司将评估这些教育和外展活动。

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.