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链和元素循环中扮演着至关重要但鲜为人知的角色。对于较小的以粘液为食的胶状动物尤其如此，包括远洋被毛类动物(盐生、火焰目、幼虫和多年生动物)。陨石在世界大陆架的颗粒物和营养丰富的水域形成大量水华，通常超过1,000个动物m-3，延伸100‘S公里。这些水华可能会改变海洋食物链的结构和功能。当甲壳类浮游动物(桡足类)是浮游植物的主要消费者时，它们滋养较大的物种，如鱼、鸟和海洋哺乳动物。研究人员假设，与之相反，多丽晶的开花促进了微生物循环过程，导致营养转移到较大消费者的效率较低。在这个项目中，研究人员研究了在亚热带大陆架系统中，多晶石在连接和修改微生物环和经典食物网过程中所起的作用。除了该项目侧重于生物海洋学的一个中心主题外，该项目的结果也引起了更广泛的兴趣。具体地说，胶状浮游动物仍然是生态系统模型中分辨率较差的组成部分，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，将改善对种群和生态系统层面对无数环境应激源的反应的预测。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中的代表性，为K-12教育工作者提供经验研究机会，支持2名博士生和几名本科生，并在其学术生涯开始时邀请一名调查人员参与。该项目的长期目标是了解亚热带大陆架上的浮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°N的中大陆架进行的海洋实地考察和两次较长的纵向考察并辅之以实验研究，调查了浮石丰度与生命阶段组成的关系、它们与海洋雪团和其他浮游动物、水柱微生物活动、细菌生产和净系统生产力的空间关系。利用微生物和浮游动物生态学中的一系列现代和经典方法，包括在南大西洋海湾部署原位浮游动物成像系统，微生物元基因组学和转录组学，以及稳定的基于同位素的示踪实验，这些研究将允许检验三个基本假设。首先，与总的货架生产力无关，与多糖类不丰富的时期相比，多糖类的存在和丰度与异养相关。其次，堆积物可以预测地塑造大陆架微生物群落、活动和功能，第三，堆积物是碎屑的喂食者，从微生物聚集颗粒和粪便材料的消费中受益--它们也对此做出了贡献。这一奖项反映了NSF的法定使命，并通过使用基金会的智力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.