LMER: Plum Island Sound Comparative Ecosystems Study (PISCES): Effects of Land Use and Organic Matter - Nutrient Interactions on Estuarine Trophic Dynamics

几十年来，河口的营养物质运动及其对初级生产力、氧气消耗、栖息地结构和沿岸水域营养变化的影响一直是河口研究的主要内容。陆地和沿海水域之间的另一个被忽视的联系是溶解有机碳和颗粒有机碳和有机氮的输入。有机氮的投入往往大于无机氮的投入，在许多情况下，来自土地的有机碳的投入大于有机碳的就地生产。尽管陆地有机质输入在数量上具有重要意义，但关于其在沿海水域的实际利用的数据很少，关于有机质负荷对沿海生态系统结构和功能影响的数据更少。溶解有机C和N的化学分析和稳定同位素示踪技术的最新发展现在使改进投入产出预算成为可能，也解决了从陆地进入沿海水域的有机物的命运和重要性。本项目解决的两个广泛问题是：(1)不同土地覆盖和用途的流域的有机碳和有机氮输入对河口生态系统的重要性是什么？(2)无机营养物与有机碳和有机氮的数量和质量的相互作用是否在决定河口营养结构、产量和营养效率中起重要作用？这个项目将试图通过测量从陆地进入沿海水域的溶解有机碳和颗粒有机碳和有机氮的数量来回答这些问题，通过实验确定各种营养物质和有机物输入及其相互作用对包括高营养水平在内的中上层和底栖食物网中碳和氮的流动和再循环的影响，并通过建立食物链转化模型以及土地利用和土地覆盖变化的影响。该研究将河口生物地球化学与更高营养水平的食物网和种群生物学研究相结合。具体地点的研究将集中在梅岛音响系统的冷水阿卡迪亚生物地理省在新英格兰北部。该项目寻求适用于各种沿海水域的结论和模式；跨生态系统的特定问题的假设检验是实现这一目标的最有效方法。该项目将结合梅岛声音生态系统的实验研究和不同海岸站点（LMER/LTER）的比较研究，选择代表末端成员来分析有机物质和无机营养负荷之间的相互作用。

Nutrient movement into estuaries and the resulting effects on primary productivity, the depletion of oxygen, habitat structure, and trophic changes in coastal waters have dominated estuarine research for decades. Another, and neglected, linkage between land and coastal waters is the input of dissolved and particulate organic carbon and organic nitrogen. Organic nitrogen inputs are frequently greater than inorganic nitrogen inputs and in many cases the input of organic carbon from land is greater than the in situ production of organic carbon. Despite the quantitative importance of organic matter inputs from land, there is little data on its actual use in coastal waters and even less data on effects of organic matter loading on coastal ecosystem structure and function. Recent developments in the chemical analysis of dissolved organic C and N and stable isotope tracer technology now make it possible to refine the input-output budgets and also address the fate and importance of organic matter entering coastal waters from land. Two broad questions addressed in this project are: (1) What is the importance to estuarine ecosystems of organic carbon and organic nitrogen inputs from watersheds with various land covers and uses? and (2) Does the interaction of inorganic nutrients with the quantity and quality of organic carbon and organic nitrogen play an important role in determining the trophic structure, production, and trophic efficiency in estuaries? This project will attempt to answer these questions through measurements of the quantity of dissolved and particulate organic carbon and organic nitrogen entering coastal waters from land, through experiments to determine the effects of various nutrient and organic matter inputs and interactions on the flow and recycling of C and N through pelagic and benthic food webs including higher trophic levels, and through modeling of food chain transformations and the effects of changes in land use and land cover. The proposed research integrates estuarine biogeochemistry with studies of food webs and population biology of higher trophic levels. Site-specific research will be focused in the Plum Island Sound System of the cold-water Acadian Biogeographic Province in northern New England. This projects seeks conclusions and models that are applicable across a wide range of coastal waters; hypothesis testing of specific questions across ecosystems is the most effective way to achieve this goal. This project will combine experimental studies in the Plum Island Sound Ecosystem with comparative studies at different coastal sites (LMER/LTER) chosen to represent end-members in an analysis of interactions between organic matter and inorganic nutrient loading.