Coupled Intensification of Nitrogen and Phosphorus Cycles in the Subtropical North Pacific Ocean

该项目寻求关于北太平洋营养不良的北太平洋氮(N)和磷(P)之间相互作用的基本信息，以及它们与生态系统生产和出口的速率和机制的关系。这项研究是在以下一般假设的指导下进行的：“与气候有关的上层栖息地结构的变化选择了固氮细菌，导致N和P循环速率的耦合加剧，迫使系统从N-限制到P-限制，产生了许多生态和生物地球化学后果。这种从N限制到P限制的假设转变影响了群落结构、初级生产总值和出口率，以及溶解物质和颗粒物质池的元素(C、N、P)化学计量比。研究人员将进行一系列野外和实验室实验，旨在评估北太平洋副热带环流营养动态耦合强化模型的几个生态预测，主要侧重于磷池动态。实地研究将在STA进行。Aloha(北纬22度45‘，西经158度)，将补充正在进行的夏威夷海洋时间序列(热)岩心测量计划。这些工作将集中在：(1)溶解无机磷的吸收和再矿化速率，(2)溶解有机磷库的产生速率，化学特性和生物有效性，以及(3)毛霉菌和原氯球菌的生理生化评估。该项目所获得的知识将用于加深我们对北太平洋少营养生态系统的了解，并预测海洋生物栖息地对环境变化和全球气候变化的反应。

This project seeks fundamental information on the interactions between nitrogen (N) and phosphorus (P) in the oligotrophic North Pacific Ocean, and their relationships to rates and mechanisms of ecosystem production and export. The research is guided by the following general hypothesis: "Climate-related shifts in the structure of the epipelagic habitat have selected for N2-fixing bacteria, resulting in a coupled intensification of N and P cycling rates which has forced the system from N- to P-limitation with numerous ecological and biogeochemical consequences. This hypothesized shift from N- to P-limitation has affected community structure, rates of gross primary production and export, and the elemental (C, N, P) stoichiometry of dissolved and particulate matter pools. The investigators will conduct a series of field and laboratory experiments designed to evaluate several ecological predictions of this coupled intensification model of nutrient dynamics in the North Pacific Subtropical Gyre with a primary focus on P pool dynamics. The field research will be conducted at Sta. ALOHA (22 degrees 45'N, 158 degrees W) and will complement the ongoing Hawaii Ocean Time-series (HOT) core measurement program. These efforts will focus on: (1) dissolved inorganic P uptake and remineralization rates, (2) dissolved organic P pool production rates, chemical characterizations and bioavailability and (3) physiological and biochemical assessments of Trichodesmium and Prochlorococcus. Knowledge derived from this project will be used to refine our understanding of the oligotrophic North Pacific ecosystem and to predict the response of oceanic habitats to environmental variability and global climate change.