Collaborative Research: The structure of arthropod food webs: consequences of nutrient-loading scenarios for productivity, trophic composition and food-chain length.

尽管越来越多的景观经历了农业和发展带来的养分流失，但人们对不同营养投入制度对自然栖息地食物网结构的影响仍然知之甚少。这个项目的智力价值在于它扩展了食物网理论，包括复杂的营养动态，不仅影响植物的生产力，也影响消费者之间的互动。研究人员将利用野外操作试验和不同氮输入沼泽调查相结合的方法，研究营养补贴对以米草属草为主的沿海盐沼食物网动态的影响。长期目标是了解一个以广泛杂食和同业捕食为特征的系统中初级生产力与食物链长度和营养组成之间的关系。这项研究的广泛影响超出了生态学理论的检验和发展。由于沿海湿地在受海浪保护的海岸线的生态和地质中起着关键作用，并且是商业鱼类和贝类的繁殖地，因此它们的保护是一个重要的问题。城市发展和农业正在危及这些湿地；氮径流促进植物生长，进而对所有其他盐沼居民产生深远影响。盐沼对反复添加氮的恢复能力尚不清楚。该研究将为博士后、研究生和本科生提供多样化的教育机会。调查人员计划参加哥伦比亚特区暑期青年就业计划，每年夏天从华盛顿特区市区雇佣两名高中生。这个项目将哥伦比亚特区的居民与雇主相匹配，这样学生就可以获得新的职业机会。

The effects of contrasting nutrient-input regimes on food-web structure in natural habitats remain poorly understood, despite the increasing fraction of landscapes experiencing nutrient runoff from agriculture and development. The intellectual merit of this project lies in its expansion of food-web theory to include complex nutrient dynamics that affect not only plant productivity but also interactions among consumers. The investigators will examine the effects of nutrient subsidies on food web dynamics in coastal salt marshes dominated by Spartina cordgrasses using a blend of manipulative field experiments and surveys of marshes that vary in nitrogen inputs. The long-term goal is to understand the relationship between primary productivity and food chain length and trophic composition in a system characterized by extensive omnivory and intra-guild predation.The broader impacts of this study extend beyond the testing and development ofecological theory. Because coastal wetlands play a critical role in the ecology and geology of wave-protected shorelines and are the nursery grounds for commercial fish and shellfish, their conservation is of major concern. Urban development and agriculture are jeopardizing these wetlands; nitrogen runoff increases plant growth, which subsequently has profound effects on all other salt marsh inhabitants. The resilience of salt marshes to repeated bouts of nitrogen addition is poorly understood. The proposed research will provide diverse educational opportunities for a postdoctoral researcher, graduate and undergraduate students. The investigators plan to participate in the District of Columbia Summer Youth Employment Program to hire two high school students from the metropolitan Washington, DC area each summer. This program matches residents of the District of Columbia with employers so that the students may gain exposure to new career opportunities.