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

许多科学论文详细描述了黑海的环境变化，许多论文推测了进一步潜在的人为变化的影响：1)为黑海提供淡水的各种流域，2)沿海边缘，3)资源的开采。虽然工业活动和不断变化的土地和水利用的生态影响在黑海沿海地区最为明显，但它们在近海也很明显。例如，在20世纪70年代中期至90年代初，整个海洋中部地区所观察到的营养物浓度增加和浮游植物生物量和初级生产力加倍的趋势已被归因于人为原因。也许最引人注目的全流域变化与偶然引入的肉食性胶状浮游动物有关，最近的是雷氏记忆藻。这些物种深刻地影响了黑海的群落结构。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使得现代建模工作中物理和生物过程之间的联系达到了最现实的状态。这些模型中最重要的是基于氮的，它们导致了关于驱动浮游生物生产的氮来源的猜想。但是，对每年氮循环的动态没有进行实际的研究，特别是没有确定黑海的新产量。此外，已经做出的概括，例如在模型中，是基于黑海浮游生态系统在过去十年环境变化之前的可概括行为。麦卡锡博士与土耳其的同事一起制定了一项计划，以填补黑海欣快带氮循环动力学方面的知识空白。在浮游生物群落和地球物理结构的背景下，将使用稳定同位素技术测量溶解组分的氮吸收、氮固定和氮通量速率。这项研究将有助于记录当前的条件，为推断最近的环境变化的影响提供基础，并有助于黑海生态系统更现实的建模工作。这项提议的合作响应了一个前所未有的机会，可以非常有效地调查黑海开放水域的氮循环。METU海洋科学研究所的土耳其科学家刚刚启动了一个密集的项目来研究“黑海低营养水平的动态：生物地球化学过程和系统建模”。该项目的第一次实地考察已经开始，但缺少一个关键组成部分，即营养物和颗粒库以及营养水平之间的氮通量动力学。探索性研究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.