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

拟议研究计划的总体目标是了解微生物群落（统称为浮游植物和其他微生物）对海水温度升高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。多管齐下的方法涉及在西北地区建立的微生物观测站，包括每周到每年的海岸站采样（贝德福德盆地），在苏格兰大陆架上的春季和秋季任务（与DFO合作），以及在拉布拉多海的年度采样。该研究以已建立的国际合作（GEOMAR、WHOI）为基础，并开发新的合作（AWI、IUEM、CIIMAR），从而与国际时间序列联系起来，并确保观测结果的互操作性。在国家环境行动计划的范围内扩大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有关的微生物群落的研究上。拟议的研究建立在先前关于重氮营养体和固氮及其相关微生物群落的工作基础上。近年来，人们已经清楚地认识到，非光合微生物构成了重氮营养物多样性的大部分。评估非光合重氮营养体在其整体细胞代谢和其特有微生物群落中的贡献和功能，以及它们固定氮的能力是很重要的。在PI实验室最近的一项突破中，分离出一种广泛分布的异养重氮营养菌，从而表征了与重氮营养生活方式相关的聚羟基丁酸酯（PHB）的生产，这种化合物用于合成可生物降解的塑料。进一步的研究将使用转录组学、蛋白质组学和代谢组学方法来阐明这种微生物的代谢。拟议的研究将依赖于已建立的时间序列平台来实现以下目标：i)通过NWA的微生物观测站，建立当前基线和微生物群落的相关变异，以表征NWA的战略位置（沿海海湾、斯科舍大陆架和拉布拉多海）。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。ii)对来自Scotian Shelf和NWA的天然微生物群落和新分离的微生物，包括固氮微生物（重氮营养菌）进行操作实验。（三）将已开发的方法和从目标（一）和（二）中获得的知识转移到具体的水产养殖环境中，以便比较和对比鲑鱼水产养殖场和包括斯科舍大陆架在内的周围沿海地区的微生物群落。

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.