Collaborative Research: Defining the biogeochemical drivers of diatom physiological ecology in the North Atlantic

地球上大约一半的光合作用是由海洋浮游植物产生的，浮游植物是随潮汐和水流漂流的单细胞生物。在浮游植物中，硅藻进行了近一半的光合作用，对全球碳循环产生了深远的控制。尽管它们很重要，但在理解硅藻在其自然环境中的功能方面存在令人惊讶的根本差距，部分原因是缺乏评估原位生理学的方法。该项目的重点是应用一种强大的新方法，称为定量代谢指纹（QMF），以解决这一知识差距，并检查该领域的物种特异性生理学。该项目将为海洋地球化学如何控制硅藻的分布，个别硅藻物种的代谢反应以及硅藻物种之间的代谢潜力如何分配提供变革性的见解，从而为海洋系统的结构和功能提供新的见解。总体目标是研究硅藻物种如何应对海洋省份的生物地球化学变化，从沿海到开阔的海洋，通过以下变化，硅藻生理学使用QMF。这项研究对于了解海洋浮游植物未来对气候和环境变化的反应至关重要。此外，该项目的活动将包括支持一名研究生和博士后研究员，并向纽约大都会地区的不同中学适龄儿童和教师以及国际扶轮女童子军中的中学女生提供艺术海洋学家方案，预计每年将有60名儿童和30名教师参加。该计划将促进多学科的实践学习，并将直接影响干教育在管道中的一个关键点，针对不同的中学年龄组在纽约和RI。在培养分离的实验室研究中，硅藻物种对营养限制的反应之间存在着深刻的差异。因此，不同物种对养分吸收、碳通量和埋藏的贡献可能不同。然而，海洋生态系统模型往往只依赖于一个物种的生理属性，并将这些属性应用于全球（例如，沿海物种用于模拟开阔海洋动态），或选择一个单一的平均值来代表世界海洋中的所有物种。在某种程度上，这是由于对硅藻生理生态学的理解相对较差，以及用于评估原位硅藻生理生态学的工具集有限。该研究项目将通过使用最先进的物种特异性方法明确跟踪代谢途径、测量其调节并确定其在一系列具有环境意义的硅藻中的分类分布来解决这一特定挑战。 一个研究探险队被设置在北大西洋，一个在碳循环中发挥重要作用的系统。从一个新英格兰沿海大陆架站点开始，将从硅藻茁壮成长的海岸到开阔的海洋和一个长期海洋时间序列站（百慕大大西洋时间序列）的站点收集样本，在该站点硅藻生长受到营养限制。这项研究利用了新的海洋观测站倡议（OOI）和时间序列信息。通过研究考察和下游实验室实验，将确定一系列环境重要硅藻中营养代谢和相关基因表达的分子途径。数据将结合起来，以预测主要的限制因素和潜在的重要基板硅藻跨海洋省份。重要的是，这种综合方法利用分子和生物信息学工具的新进展，在物种特异性水平上研究原位生理生态学，这是该领域的一个关键知识空白。

About half of photosynthesis on earth is generated by marine phytoplankton, single celled organisms that drift with tides and currents. Within the phytoplankton, the diatoms conduct nearly half of this photosynthesis, exerting profound control over global carbon cycling. Despite their importance, there are surprisingly fundamental gaps in understanding how diatoms function in their natural environment, in part because methods to assess in situ physiology are lacking. This project focuses on the application of a powerful new approach, called Quantitative Metabolic Fingerprinting (QMF), to address this knowledge gap and examine species-specific physiology in the field. The project will provide transformative insights into how ocean geochemistry controls the distribution of diatoms, the metabolic responses of individual diatom species, and how metabolic potential is partitioned between diatom species, thus providing new insights into the structure and function of marine systems. The overarching goal is to examine how diatom species respond to changes in biogeochemistry across marine provinces, from the coast to the open ocean, by following shifts in diatom physiology using QMF. This research is critical to understand future changes in oceanic phytoplankton in response to climate and environmental change. Furthermore, activities on this project will include supporting a graduate student and postdoctoral fellow and delivering the Artistic Oceanographer Program (AOP) to diverse middle school age children and teachers in the NYC metropolitan area and to middle-school girls in the Girl Scouts of RI, reaching an anticipated 60 children and 30 teachers annually. The programs will foster multidisciplinary hands-on learning and will directly impact STEM education at a critical point in the pipeline by targeting diverse middle-school aged groups in both NY and RI.In laboratory studies with cultured isolates, there are profound differences among diatom species' responses to nutrient limitation. Thus, it is likely that different species contribute differently to nutrient uptake, carbon flux and burial. However, marine ecosystem models often rely on physiological attributes drawn from just one species and apply those attributes globally (e.g. coastal species used to model open ocean dynamics) or choose a single average value to represent all species across the world's oceans. In part, this is due to a relatively poor understanding of diatom physiological ecology and a limited tool set for assessing in situ diatom physiological ecology. This research project will address this specific challenge by explicitly tracking metabolic pathways, measuring their regulation and determining their taxonomic distribution in a suite of environmentally significant diatoms using a state of the art, species-specific approach. A research expedition is set in the North Atlantic, a system that plays a major role in carbon cycling. Starting with a New England coastal shelf site, samples will be collected from the coast where diatoms thrive, to the open ocean and a site of a long term ocean time series station (the Bermuda Atlantic Time Series) where diatom growth is muted by nutrient limitation. This research takes advantage of new ocean observatories initiative (OOI) and time series information. Through the research expedition and downstream laboratory experiments, the molecular pathways of nutrient metabolism and related gene expression in a suite of environmentally significant diatoms will be identified. Data will be combined to predict major limiting factors and potentially important substrates for diatoms across marine provinces. Importantly, this integrated approach takes advantage of new advances in molecular and bioinformatics tools to examine in situ physiological ecology at the species-specific level, a key knowledge gap in the field.