POWRE: Nitrogen Cycling in a Lagoonal Land Margin Ecosystem: Importance of Dissolved Organic Nitrogen

9805928 McGlathery河口和浅泻湖是陆地和海洋生态系统之间的联系，并接受大量的营养物质和有机物的外部输入。来自沿海流域的过量无机营养物负荷与初级生产的增加以及受纳沃茨的生境结构和营养动态的变化直接相关。相比之下，对近岸系统中有机营养物的循环和生物利用度知之甚少，尽管这些系统的有机营养物输入有时可能高于无机负荷。该POWRE奖重点关注溶解有机氮（DON）作为浅水沿海沃茨氮循环的潜在重要组成部分。沿海泻湖和海湾构成了大多数大陆上的一种主要的陆缘生态系统，但通过这些系统的营养物质的保留和运输受到的关注远远低于大型河口。这些系统之间的氮循环过程中的一个主要区别是，底栖初级生产者在浅水沿海泻湖和海湾的营养转化的影响很大。沉积物-水界面的交换在泻湖系统的营养循环中起着关键作用，因为水柱混合良好，体积相对于大的沉积物表面积较小。结合现场观测，实验室实验和数值模拟将被用来测试假设之间的相互作用和有机质负荷，DON通量，和底栖植物。结果将有助于我们预测不同的加载制度的后果，以沿海泻湖系统和可能的缓解措施，以减少在浅水海岸系统的富营养化的影响的有效性的能力。

9805928 McGlathery Estuaries and shallow lagoons are the link between terrestrial and oceanic ecosystems and receive considerable external inputs of nutrients and organic matter. Excess inorganic nutrient loading from coastal watersheds has been directly related to increases in primary production and to changes in habitat structure and trophic dynamics in receiving waters. By comparison, little is known about the cycling and bioavailability of organic nutrients in nearshore systems, even though organic nutrient inputs to these systems can sometimes be higher than inorganic loadings. This POWRE award focuses on dissolved organic nitrogen (DON) as a potentially important component of the nitrogen cycle in shallow coastal waters. Coastal lagoons and bays constitute a major type of land margin ecosystem on most continents, but the retention and transport of nutrients through these systems have received far less attention than in large estuaries. A major difference in the nitrogen cycling processes between these systems is the large influence that benthic primary producers have on nutrient transformations in shallow coastal lagoons and bays. Exchanges across the sediment-water interface play a key role in nutrient cycling in lagoonal systems because the water column is well-mixed and small in volume relative to the large sediment surface area. A combination of field observations, laboratory experiments and numerical modeling will be used to test hypotheses regarding interactions between and among organic matter load, flux of DON, and benthic plants. The results will aid our ability to predict both the consequences of different loading regimes to coastal lagoonal systems and the effectiveness of possible mitigation efforts to reduce the effects of eutrophication in shallow coastal systems.