New Production and Nitrogen Cycling in the Off-Shore Regions of the Black Sea

许多科学论文详细描述了黑海的环境变化，许多人推测了进一步潜在的人为变化的影响：1）在为黑海提供淡水的各种流域，2）沿沿着其海岸边缘，3）在其资源的开采中。虽然工业活动和改变土地和水的使用对生态的影响在黑海沿海地区最为明显，但在海岸以外也很明显。例如，1970年代中期至1990年代初期，在整个海洋中部区域观察到的营养物浓度和浮游植物生物量和初级生产力的增加趋势，被认为是人为原因造成的。 也许最引人注目的流域范围的变化，但是，由于偶然引进的食肉性凝胶状浮游动物，最近Mnemiopsis leydii。这些物种深刻地影响了黑海的社会结构，并可能社区动态方面的元素和能量流。 没有对黑海的年度氮循环进行研究，也没有确定黑海的新产量。此外，已作出的概括，如在模型中，预测的黑海浮游生态系统的广义行为之前，过去十年的环境变化。 将与土耳其的同事一道，彻底调查所有四季的离岸海岸氮循环。氮的吸收率，固氮，溶解组分之间的氮通量将与稳定同位素技术进行测量，并在浮游生物群落结构和水文的背景下解释。这项研究将有助于记录目前的条件，提供了一个基础，推断最近的环境变化的影响，并有助于更现实的模拟黑海生态系统的努力。在这项工作中，我们的土耳其同事将在设计、分析和解释氮通量实验结果方面获得经验，我们的设施将供他们对黑海不断变化的情况进行后续研究。 黑海的物理规模使其远洋生态系统的全面研究易于进行。在这方面，黑海是一个重要的资源，可用于发展和测试对远洋浮游生物领域更广泛应用的物理和生物地球化学耦合模型中的生态系统功能和稳定性的认识。

Many scientific papers have been written that detail environmental changes in the Black Sea, and many speculate regarding 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, however, resulted from accidental introductions of carnivorous gelatinous zooplankton, most recently Mnemiopsis leydii. These species have profoundly affected Black Sea community structure, and probably community dynamics with respect to element and energy flow. There have been no studies of the annual nitrogen cycle and no determinations of new production in the Black Sea. Moreover, generalizations that have been made, such as in models, are predicated upon the generalized behavior of a Black Sea planktonic ecosystem prior to the environmental changes of the last decade. In conjunction with colleagues in Turkey, the off shore nitrogen cycle during all four seasons will be thoroughly investigated. Rates of nitrogen uptake, nitrogen fixation, and nitrogen flux among dissolved components will be measured with stable isotope techniques and interpreted within the context of plankton community structure and hydrography. 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. In the course of this work our Turkish colleagues will gain experience in the design, analysis and interpretation of results of nitrogen flux experiments, and our facilities will be available to them for follow on studies of changing conditions in the Black Sea. The physical scale of the Black Sea makes a comprehensive study of its pelagic ecosystem tractable. In this regard the Black Sea is an important resource for developing and testing understanding of ecosystem function and stability in more broadly applied coupled physical and biogeochemical models of the pelagic plankton realm.