DISSERTATION RESEARCH: Hydrological characteristics, trophic interactions, and fish assemblage structure in temperate stream systems

流经河流和溪流的水量和可变性是淡水生物多样性，特别是鱼类生物多样性的主要调节因素。这种调节部分是由于特殊流动条件所施加的能量限制。例如，一些物种较好地适应了获取食物资源的快速水流，而另一些物种则需要较慢的水流。除了能量限制，物种还受到生物相互作用的影响，例如与生态相似的物种的捕食和竞争。因此，如果有适量的食物资源和与其他物种合理水平的相互作用，鱼类种群将持续存在，这两个因素也受到流动条件的调节。然而，水流特征和生物相互作用在确定鱼类物种多样性方面的综合影响还没有被很好地理解。该项目通过从密苏里州东南部Meramec河系统的多个站点收集食物网数据，并将这些测量结果与溪流流动特征相关联来解决这一问题。在不同的水流状况下研究影响食物网结构的因素，将为淡水河流生态系统中调节生物多样性的主要因素提供新的信息。Meramec河流域位于欧扎克高地，代表着北美淡水生物多样性的热点。在Meramec河及其支流中发现了120多种鱼类。与此同时，Meramec河为大约25万人提供饮用水。尽管流域仍然相对原始，但由于人类对景观的修改，一些河段正在经历持续的退化。因此，Meramec河流域是密苏里州自然保护部和自然保护协会合作保护工作的主要重点，因为它具有生物重要性，而且人类对排水系统中的水资源的依赖。这项研究的结果将对这些保护机构在这一独特的水生生态系统中平衡人类活动和生物多样性保护的努力具有实际意义。此外，几名本科生将接受研究技术方面的培训，并接触到集中于水产资源保护的问题。

The volume and variability of water flowing through rivers and streams are primary regulators of freshwater biodiversity, particularly for fishes. This regulation is partially due to energetic constraints imposed by particular flow conditions. For example, some species are better adapted to fast currents for food resource acquisition, while others require slower currents. In addition to energetic constraints, species are also influenced by biological interactions such as predation and competition with ecologically similar species. Consequently, fish populations will persist given suitable amounts of food resources and reasonable levels of interactions with other species, two factors which are also regulated by flow conditions. Nevertheless, the combined effects of flow characteristics and biological interactions in determining fish species diversity are not well understood. This project addresses this issue by collecting food web data from multiple sites in the Meramec River system in southeastern Missouri and relating these measurements to stream flow characteristics. Investigating factors influencing food web structure in the context of various flow regimes will provide novel information on the primary factors regulating biodiversity in freshwater stream ecosystems. The Meramec River watershed is located in the Ozark Highlands and represents a freshwater biodiversity hotspot in North America. Over 120 species of fishes are found in the Meramec River and its tributaries. At the same time, the Meramec River supplies drinking water to approximately 250,000 people. Although the drainage area remains relatively pristine, some stream sections are experiencing ongoing degradation due to human modifications of the landscape. Consequently, the Meramec River watershed is a primary focus of collaborative conservation efforts by the Missouri Department of Conservation and The Nature Conservancy due to its biological importance and the dependence of humans on the water resources in the drainage. Results from this research will be of practical use for these conservation agencies during their attempts to balance human activities and the conservation of biodiversity in this unique aquatic ecosystem. In addition, several undergraduate students will be trained in research techniques as well as exposed to issues focused on the conservation of aquatic resources.