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

SGER：黑海近海地区的新产品和氮循环

• 批准号: 9729793
• 负责人: James McCarthy
• 金额: $ 5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9729793&HistoricalAwards=false
• 关键词: SGER; New; Productions; Nitrogen; Cycling

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.

A. 项目摘要 许多科学论文详细描述了黑海的环境变化，许多人推测进一步潜在的人为变化的影响：1) 向该海提供淡水的各个流域，2) 沿海边缘， 3) 资源开采。虽然工业活动以及土地和水资源利用变化的生态影响在黑海沿海地区最为明显，但在近海地区也同样明显。例如，在 20 世纪 70 年代中期至 90 年代初期，观察到整个海洋中部地区养分浓度增加以及浮游植物生物量和初级生产力倍增的趋势，已被归因于人为原因。 也许最引人注目的全流域变化与肉食性胶状浮游动物的意外引入有关，最近的例子是 Mnemiopsis leydii。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。主要的食物网扰动可以检验与群落组织的影响以及能量和物质流动有关的假设。 盆地尺度的物理过程变得越来越众所周知，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基于氮的，它们导致了关于驱动浮游生物生产的氮源的猜想。 然而，还没有对年度氮循环动态进行实际研究，特别是没有确定黑海的新产量。此外，已经做出的概括（例如模型中的概括）是基于过去十年环境变化之前黑海浮游生态系统的一般行为。 麦卡锡博士与土耳其的同事合作制定了一项计划，以填补黑海欣快带氮循环动态知识方面的空白。溶解成分中的氮吸收率、固氮率和氮通量将通过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当前状况，为推断近期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现实的建模工作。 这项拟议的合作响应了前所未有的机会，可以非常有效地研究黑海的开放水域氮循环。 METU海洋科学研究所的土耳其科学家刚刚启动了一项强化计划，研究“黑海低营养级的动态：生物地球化学过程和系统建模”。该计划的第一次实地活动已经开始，但缺少一个关键组成部分，即养分和颗粒库之间的氮通量以及营养水平的动态。这项用于探索性研究的小额赠款将提供这一关键组成部分。