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，但在沿海地区也很明显。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。然而，最引人注目的盆地范围变化可能是由偶然引入的肉食性胶状浮游动物造成的，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，并可能在元素和能量流动方面影响了群落动态。没有对每年的氮循环进行研究，也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一般行为。与土耳其的同事一起，将对所有四个季节的近海氮循环进行彻底调查。氮吸收速率、固氮速率和溶解组分之间的氮通量将通过稳定同位素技术进行测量，并在浮游生物群落结构和水文背景下进行解释。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。在这项工作中，我们的土耳其同事将获得设计、分析和解释氮通量实验结果的经验，我们的设施将供他们继续研究黑海不断变化的条件。黑海的物理尺度使得对其远洋生态系统的全面研究变得非常容易。在这方面，黑海是一个重要的资源，可以在更广泛应用的浮游生物领域的物理和生物地球化学耦合模型中发展和测试对生态系统功能和稳定性的理解。

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.