DISSERTATION RESEARCH: Secondary Production in Urban Stream Food Webs: From Pattern to Process

城市土地利用和未来的城市扩张对自然生态系统构成严重威胁。城市地区依靠来自自然生态系统的外部支持来获取资源和处理废物。因此，城市系统中的溪流受到分水岭内多种干扰的影响，在许多情况下，它们是城市污水排放的废物管道。此外，由于增加了不透水表面(即道路、建筑物、停车场)，流域水文发生了变化，通过加深和加宽河道以适应新的水流模式，极大地影响了河道地貌。溪流条件下的这些物理和化学变化通常导致溪流生物的生物多样性减少。然而，一个尚未解决的问题是，社区丰富度和多样性的减少如何影响城市河流社区提供的生态系统功能和服务。在这项研究中，这一问题将通过在土地利用从0到80%的城市覆盖率变化的六条溪流排水流域进行实验来解决，以确定城市化不仅对溪流中的生物多样性产生了影响，而且这些生物多样性的损失对溪流食物网中的能量流动和养分循环产生了什么后果，这两个过程对溪流中的水质产生了深远的影响。这些成果的传播将通过将通常观察到的河流生物多样性的减少与河流生物提供的可测量的生态系统规模功能和服务联系起来，促进未来城市化河流的规划、管理和恢复。

Urban land use and future urban expansion pose a serious threat to natural ecosystems. Urban areas rely on outside support from natural ecosystems for resource acquisition and waste disposal. As a consequence, streams in urban systems are affected by multiple disturbances within the watershed, and, in many cases, serve as waste conduits for municipal wastewater discharge. In addition, changes in watershed hydrology due to increased impervious surfaces (i.e. roads, buildings, parking lots) drastically affect stream channel geomorphology by deepening and widening the stream to accommodate new flow patterns. These physical and chemical changes in stream conditions generally result in decreased biological diversity of stream dwelling organisms. An unaddressed question, however, is how reductions in community richness and diversity affect the ecosystem functions and services provided by urban stream communities. In this study, this question will be addressed by conducting experiments in six streams draining watersheds in which land use varies from 0 to 80% urban cover to determine not only how biological diversity within the stream is impacted by urbanization, but what consequences these losses in biological diversity have in terms of energy flow and nutrient cycling within stream food webs, two processes with profound consequences for in-stream water quality. Dissemination of these results will facilitate the future planning, management, and restoration of urbanized streams by linking commonly observed decreases in stream biological diversity with measureable ecosystem scale functions and services provided by the stream organisms.