The impact of oceanic microbial communities on marine biogeochemistry now and in the future

拟议的研究计划的首要目标是了解微生物群落(统称浮游植物和其他微生物)对海水温度上升和营养物质库存减少的反应，以及这将如何影响西北大西洋(NWA)和世界海洋其他采样不足地区的初级生产力。多管齐下的办法包括在西北部建立微生物观测站，包括每周至每年对岸上站(贝德福德盆地)进行采样，在斯科特大陆架执行春季和秋季任务(与DFO合作)，以及在拉布拉多海进行年度采样。这项研究建立在已建立的国际合作(全球海洋观测系统、世界卫生组织)的基础上，并发展新的国际合作(AWI、IUEM、CIIMAR)，从而与国际时间序列挂钩，并确保观测的互操作性。在西北地区范围内扩展对微生物群落结构和功能的研究，PI将把她的专业知识转移到与水产养殖业相关的微生物群落的研究上。这项拟议的研究建立在以前关于重氮菌和固氮菌及其相关微生物群落的工作基础上。近年来，很明显，非光合作用的微生物构成了重氮菌多样性的主体。重要的是评估非光合作用的重氮菌在其全球细胞新陈代谢的背景下和在其特有的微生物群落中的贡献和功能，以及它们固定氮的能力。在PI实验室最近的一项突破中，分离出了一种广泛分布的异养重氮菌，从而表征了与重氮化生活方式有关的聚羟基丁酸酯(PHB)的生产，这是一种用于合成可生物降解塑料的化合物。进一步的研究将使用转录组、蛋白质组和代谢组学的方法来阐明这种微生物的新陈代谢。拟议的研究将依靠已建立的时间序列平台来实现以下目标：i)与西澳大利亚的微生物观测站合作，建立微生物群落的当前基线和相关变异性，以确定西澳大利亚(沿海海湾、斯科特陆架和拉布拉多海)的战略位置。这将有助于探索微生物群落组成和代谢功能如何响应环境条件的变化。二)对自然微生物群落和新的微生物分离物，包括来自斯科特大陆架和西北部的固氮菌(重氮菌)进行操控实验。将开发的方法和从目标(I)和(Ii)获得的知识转移到具体的水产养殖环境，以比较和对比鲑鱼水产养殖场和周围沿海地区，包括斯科特大陆架的微生物群落。

The overarching goal of the proposed research program is aimed at understanding the response of the microbial community (collectively phytoplankton and other microbes) to increasing seawater temperature and decreasing nutrient inventory and how this will affect primary productivity in the Northwest Atlantic (NWA) and other under-sampled regions of the world's ocean. A multi-pronged approach engages established microbial observatories in the NWA, including weekly to annual sampling of in-shore stations (Bedford Basin), spring and fall missions on the Scotian Shelf (in collaboration with DFO), and yearly sampling in the Labrador Sea. The research builds on established international collaborations (GEOMAR, WHOI) and develops new ones (AWI, IUEM, CIIMAR), thereby linking to international time-series and ensuring interoperability of the observations. Extending the research on microbial community structure and function within the context of the NWA, the PI will transfer her expertise to the study of microbial communities associated with the aquaculture industry. The proposed research builds on previous work on diazotrophs and nitrogen fixation as well as their associated microbial communities. In recent years, it has become clear that non-photosynthetic microbes make up the bulk of the diazotroph diversity. It is important to assess the contribution and function of the non-photosynthetic diazotrophs in the context of their global cell metabolism and within their characteristic microbial community, in addition to their ability to fix nitrogen. In a recent breakthrough in the PI's laboratory, the isolation of a widely distributed heterotrophic diazotroph has led to characterization of the production of polyhydroxybutyrate (PHB) linked to the diazotrophic lifestyle, a compound used in the synthesis of biodegradable plastic. Further studies will use transcriptomic, proteomic, and metabolomic approaches to elucidate the metabolism of this microorganism. The proposed research will rely on established time-series platforms to carry out the following objectives: i) With the microbial observatory in the NWA, establish the current baseline and associated variability in the microbial community to characterize strategic locations in the NWA (Coastal embayment, Scotian Shelf, and Labrador Sea). This will serve to explore how microbial community composition and metabolic function respond to changes in environmental conditions. ii) Perform manipulative experiments on natural microbial communities and new microbial isolates, including N2-fixing microbes (diazotrophs), from the Scotian Shelf and the NWA. iii) Transfer the developed approaches and the knowledge gained from objectives (i) and (ii) to specific aquaculture settings in order to compare and contrast microbial communities of salmon aquaculture farms and those of the surrounding coastal areas including the Scotian Shelf.