The significance of doliolid-microbial interactions: Do doliolids fundamentally alter the trophic structure and productivity of sub-tropical continental shelf food webs?

胶状浮游动物在世界海洋的食物网和元素循环中起着至关重要的作用，但人们对其知之甚少。对于较小的以黏液为食的胶状动物来说尤其如此，包括远洋被囊动物（海鞘、火虫、幼虫和水母）。在世界大陆架的颗粒和营养丰富的水域中，水螅体形成大量的水华，通常超过1000个动物的米-3，延伸100公里，这些水华很可能改变海洋食物网的结构和功能。当甲壳类浮游动物（桡足类）是浮游植物的主要消费者时，它们会滋养更大的物种，如鱼类、鸟类和海洋哺乳动物。研究人员假设，与此相反，水母繁殖增强了微生物循环过程，导致营养转移到较大消费者的效率较低。在这个项目中，研究人员研究了亚热带大陆架系统中胶粒在连接和修改微生物环和经典食物网过程中的作用。除了该项目关注生物海洋学的中心主题外，该项目的结果还具有更广泛的意义。具体来说，胶状浮游动物仍然是生态系统模型中一个难以解决的组成部分，更好地了解这些群落如何与微生物过程相互作用并受到化学和物理条件的影响，将改善种群和生态系统水平对无数环境压力源的反应的预测。该项目支持一项有针对性的努力，以增加非裔美国人在海洋科学领域的代表性，为K-12教育工作者提供体验式研究机会，支持2名博士生和几名本科生，并包括一名刚开始学术生涯的研究者。本项目的长期目标是了解亚热带大陆架上油石的生态功能及其对微生物过程的影响。该项目结合每月在北纬31°的中大陆架进行的海洋实地考察和两次更长的纵向考察，并辅以实验研究，调查了水母丰度与生命阶段组成之间的关系，它们与海洋雪聚集体和其他浮游动物的空间关系，水柱微生物活动，细菌生产和净系统生产力。利用微生物和浮游动物生态学的现代和经典方法，包括在南大西洋湾部署原位浮游动物成像系统，微生物宏基因组学和转录组学以及基于稳定同位素的示踪剂实验，这些研究将允许测试三个基本假设。首先，与整个大陆架生产力无关，与不丰富的时期相比，油性磷脂的存在和丰度与异养相关。第二，可以预见的是，微球塑造了大陆架微生物群落、活动和功能；第三，微球是碎屑饲料，从富含微生物的聚集颗粒和粪便物质的消耗中获得营养——它们也为这个池做出了贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Gelatinous zooplankton play crucial but poorly understood roles in food webs and element cycling in the world's oceans. This is especially true for smaller mucus-feeding gelatinous animals including the pelagic tunicates (salps, pyrosomes, larvaceans, and doliolids). Doliolids form massive blooms in particle and nutrient-rich waters of the world’s continental shelves, often exceeding 1,000 zooids m-3 and extending 100’s of km. These blooms are likely to alter the structure and function of marine food webs. When crustacean zooplankton (copepods) are the primary consumers of phytoplankton they nourish larger species such as fish, birds, and marine mammals. The investigators hypothesize that doliolid blooms, in contrast, enhance microbial loop processes leading to a lower efficiency of trophic transfer to larger consumers. In this project, the investigators examine the role that doliolids play in linking and modifying microbial loop and classical food web processes in subtropical continental shelf systems. In addition to the project’s focus on a central theme in biological oceanography, the results of this project are of broader interest. Specifically, gelatinous zooplankton remain a poorly resolved component of ecosystem models, and a better understanding of how these communities interact with microbial processes and are influenced by chemical and physical conditions will improve predictions of population- and ecosystem-level responses to the myriad of environmental stressors. The project supports a targeted effort to increase the representation of African Americans in the Ocean Sciences, provides experiential research opportunities to K-12 educators, supports 2 PhD students and several undergraduate students, and involves an investigator at the beginning of his academic career.The long-term goal of this project is to understand the ecological function of doliolids on subtropical continental shelves and their influence on microbial processes. In association with monthly oceanographic field expeditions on the mid-continental shelf at 31°N and two longer longitudinal expeditions complemented with experimental studies, the project investigates the relationship between doliolid abundance and life stage composition, their spatial relationships to marine snow aggregates and other zooplankton, water column microbial activity, bacterial production, and net system productivity. Utilizing a constellation of modern and classical approaches in microbial and zooplankton ecology, including deployment of an in situ zooplankton imaging system in the South Atlantic Bight, microbial metagenomics and transcriptomics, and stable isotope-based tracer experiments, these studies will allow the testing of three fundamental hypotheses. First, independent of total shelf productivity, the presence and abundance of doliolids is correlated with heterotrophy compared to periods when doliolids are not abundant. Second, doliolids predictably shape continental shelf microbial communities, activity, and function, and third, doliolids are detrital feeders benefiting nutritionally from the consumption of microbial enriched aggregated particles and fecal material - the pool to which they also contribute.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.