Collaborative Research: Engineering salt marsh restoration to maximize denitrification - elevation and species interactions

1438092 （Mortazavi）和1438235 （Ortmann）。沿海湿地只占所有湿地面积的一小部分，但它们是独特的，因为它们也容纳了世界上很大一部分以上的人口。沿海沼泽生态系统与人类居住和工业有着动态的联系，人类对这些生态系统的影响可能是相当大的。这种耦合的人类-沼泽系统具有重要的意义，因为沼泽提供了理想的生态系统服务，如营养过滤、洪水控制和碳封存。由于这些服务和城市化导致的沼泽损失，沼泽恢复已成为沿海管理的重要工具。湿地脱氮是湿地生态系统的一项重要功能，它通过减轻富营养化而促进了沿海生态系统的可持续性。目前，沼泽的建设是基于这样的假设：一旦植被到位，反硝化作用将显著促进氮的去除；然而，研究表明，这些努力只恢复了一些理想的生态系统服务。沼泽恢复文献中缺少具体的信息，这些信息可以用来设计更有效地去除氮的沼泽。这项研究专门解决了这个问题。本研究的主要目的是阐明物种身份和沼泽高程对恢复后沼泽生态系统氮去除能力的影响，为可持续沼泽生态系统的工程设计提供指导，从而最大限度地去除氮。为了实现这一目标，该项目提出了以下假设：(i)花楸草（Juncus romerianus）的氮去除率高于互花米草（Spartina interniflora）沼泽（物种效应），（ii）存在一个最佳的沼泽表面高度，在这个高度上，氮去除量最大（海拔效应），（iii）在这个最佳海拔上，沼泽将对增加的营养最有弹性（对氮输入增加的反应）。这些假设将在野外以及在阿拉巴马州沿海沼泽的野外生态系统中进行为期三年的研究。这种方法使我们能够操纵沼泽表面海拔相对于平均海平面，以确定氮去除的最佳条件。项目结果将用于制定沼泽工程项目的具体指导方针，以确保最大限度地去除氮，这是一项重要的生态系统服务。此外，对植被-海拔-微生物群落的相互作用也将有更好的了解，为沿海沼泽氮循环提供基础知识。研究结果的综合将为修复策略提供必要的数据，包括沉积物补贴和物种选择，以优化氮的去除，从而减轻工程沼泽的富营养化。沿海沼泽提供重要的生态系统服务，如过滤沉积物、减缓洪水和保护内陆发展免受周期性风暴的影响，并为重要的商业资源提供营养和栖息地。这项研究意义重大，因为它将有助于推进我们对复杂生态系统的理解，并将帮助我们改进工程沼泽提供的生态系统服务（即氮去除）的最大化努力。本项目收集的数据将立即适用于沿海管理人员和进行沼泽重建项目的团体。研究结果将分发给当地的利益相关者，包括土地管理者、当地政府决策者和居民。为了将这些发现放在更广泛的背景下，将开发教材，供海豚岛海洋实验室的教育和推广（E&amp；O）项目使用，该项目被称为探索大厅项目（DHP），是墨西哥湾北部地区最大的沿海科学E&amp；O项目之一。

1438092 (Mortazavi) and 1438235 (Ortmann). Coastal wetlands represent a small fraction of all wetland areas, but are unique as they also host more than a significant fraction of the world's population. Coastal marsh ecosystems are dynamically linked to human dwellings and industry, and the impact humans have on these ecosystems can be considerable. This coupled human - marsh system has important implications, as the marshes provide desirable ecosystem services such as nutrient filtering, flood control, and carbon sequestration. Because of these services and the loss of marshes through urbanization, restoration of marshes has become an important tool in coastal management. Nitrogen (N) removal is an important service of marshes, which contributes to the sustainability of coastal ecosystems by mitigating eutrophication. Currently marshes are constructed with the assumption that denitrification will contribute significantly to N removal once vegetation is in place; however, studies suggest that only some of desirable ecosystem services are restored by such efforts. Specific information is missing from marsh restoration literature, which could be used to engineer marshes that are more effective at N removal. This research specifically addresses this issue.The primary objective of this research is to elucidate the impact of species identity and marsh elevation on the N removal capacity of restored marsh ecosystems to provide guidance in the engineering of sustainable marsh ecosystem which also maximize N removal. To achieve this objective the project addresses the following hypotheses: (i) rates of N removal in Juncus romerianus are higher than in Spartina alterniflora marshes (species effect), (ii) there exists an optimum marsh surface elevation where N removal is maximized (elevation effect), and (iii) at this optimal elevation, the marsh will be most resilient to increased nutrients (response to elevated N input). These hypotheses will be addressed in the field as well as with field-mesocosms in Alabama coastal marshes over a three-year period. This approach enables us to manipulate marsh surface elevation with respect to mean sea level to identify optimum conditions for N removal. Project results will be used to develop specific guidelines for marsh engineering projects to ensure N removal, an important ecosystem service, is maximized. Furthermore, a better understanding of the vegetation-elevation-microbial community interactions, providing fundamental knowledge about N cycling in coastal marshes, will be achieved. The synthesis of results from the research will provide the necessary data to inform restoration strategies, including sediment subsidy and species selection, to optimize N removal, and thus mitigate eutrophication, by engineered marshes. Coastal marshes provide important ecosystem services such as filtering sediments, moderating flooding and protecting inland developments from periodic storms, and provide nutrition and habitat for commercially important resources. The research is significant because it will help advance our understanding of a complex ecological system, and will help us refine efforts for maximizing an ecosystem service (i.e. N removal) provided by engineered marshes. The data collected during this project will be immediately applicable to coastal managers and groups carrying out marsh reconstruction projects. Results will disseminated to the local stakeholders including land managers, local government decision makers, and residents. To place the findings in a broader context, teaching material will be developed that can be used by the education and outreach (E&O) program of the Dauphin Island Sea Lab, known as the Discovery Hall Programs (DHP), one of the largest coastal science E&O programs in the northern Gulf of Mexico region.