SGER: New Productions and Nitrogen Cycling in the Off-shoreRegions of the Black Sea

答：项目摘要许多科学论文详细描述了黑海的环境变化，其中许多人推测了进一步的潜在人为变化的影响：1)为黑海提供淡水的各种流域；2)黑海的沿海边缘；3)资源的开采。虽然工业活动以及土地和水利用变化对生态的影响在黑海沿海地区最为明显，但在近海也很明显。例如，20世纪70年代中期至90年代初，在整个海洋中部区域观察到的营养物质浓度增加和浮游植物生物量和初级生产力增加一倍的趋势被归因于人为原因。也许整个盆地范围内最戏剧性的变化与肉食性胶状浮游动物的意外引入有关，最近的例子是莱氏沼虾。这些物种对黑海群落结构产生了深远的影响。黑海生态系统的许多方面使其成为生物海洋学家研究的一个有吸引力的系统。主要的食物网扰动允许测试与社区组织的影响以及对能量和物质流动的影响有关的假设。盆地尺度的物理过程正变得越来越为人所知，而这片海洋的物理尺度允许在当代建模工作中物理和生物过程之间现实的最先进的联系。这些模型中最重要的是以氮为基础的，它们导致了关于驱动浮游生物生产的氮的来源的猜测。然而，还没有关于年度氮循环动态的实际研究，特别是没有确定黑海的新产量。此外，已作出的概括，例如在模型中，是以过去十年环境变化之前黑海浮游生态系统的可概括行为为基础的。麦卡锡博士与土耳其的同事们共同制定了一项计划，以填补在黑海兴奋带氮循环动态方面的知识空白。氮吸收速率、氮固定速率和溶解组分之间的氮通量将使用稳定同位素技术进行测量，并在浮游生物群落和地球物理结构的背景下进行解释。这项研究将有助于记录目前的状况，为推断最近环境变化的影响提供基础，并有助于对黑海生态系统进行更切合实际的建模工作。这一拟议的合作回应了一个前所未有的机会，即非常有效地调查黑海公开水域的氮循环。土耳其METU海洋科学研究所的科学家刚刚启动了一个密集的项目，研究“黑海低营养层的动力学：生物地球化学过程和系统建模”。该计划的第一个实地活动已经开始，但一个关键的组成部分--营养库、颗粒库和营养层之间的氮通量动态缺乏。这笔用于探索性研究的小额赠款将提供这一关键组成部分。

A. Project Summary Many scientific papers have been written that detail environmental changes in the Black Sea, and many speculate on the implications of further potential anthropogenic changes 1) in various drainage basins that provide freshwater to this sea, 2) along its coastal margins, and 3) in extraction of its resources. While the ecological effects of industrial activity and changing land and water use are most apparent in coastal regions of the Black Sea, they are also evident off-shore. For example, the observed trend of increasing nutrient concentrations and doublings of both phytoplankton biomass and primary productivity throughout the central region of the sea between the mid 1970s and early 1990s, have been attributed to anthropogenic causes. Perhaps the most dramatic basin-wide changes have been associated with the accidental introductions of carnivorous gelatinous zooplankton, most recently Mnemiopsis leydii. These species have profoundly affected Black Sea community structure. Many aspects of the Black Sea ecosystem make it an attractive system for biological oceanographers to study. Major food web perturbations allow for testing of hypotheses relating to the influence of community organization and on the flow of energy and matter. Basin scale physical processes are becoming increasingly well known, and the physical scale of this sea allows for realistic state of the art linkages among physical and biological processes in contemporary modeling efforts. The foremost of these models are nitrogen based, and they lead to conjecture regarding the sources of nitrogen that drive plankton production. However, there have been no actual studies of the dynamics of the annual nitrogen cycle and, in particular, no determinations of new production in the Black Sea. Moreover, generalizations that have been made, such as in models, are predicated upon the generalizable behavior of a Black Sea planktonic ecosystem prior to the environmental changes of the last decade. In conjunction with colleagues in Turkey, Dr. McCarthy has developed a plan to fill these gaps in knowledge of the dynamics of the nitrogen cycle in the euphoric zone of the Black Sea. Rates of N uptake, N2 fixation, and nitrogen flux among dissolved components will be measured with stable isotope techniques and interpreted within the context of plankton community and geophysical structure. This study will serve to document current conditions, provide a basis for inferring the effects of recent environmental changes, and contribute to more realistic modeling efforts of the Black Sea ecosystem. This proposed collaboration responds to an unprecedented opportunity to investigate the openwater nitrogen cycle in the Black Sea very efficiently. Turkish scientists at the METU Institute of Marine Science have just launched an intensive program to study the "Dynamics of the lower trophic levels of the Black Sea: Biogeochemical processes, and system modeling". The first field campaign in this program has begun, but a critical component, the dynamics of nitrogen fluxes among nutrient and particulate pools and trophic levels is missing. This Small Grant for Exploratory Research will provide this critical component.