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

流经河流和小溪的水量和水量变化是淡水生物多样性的主要调节因素，特别是对鱼类而言。这种调节部分是由于特殊流动条件所施加的能量约束。例如，一些物种更适应快速的水流来获取食物资源，而另一些物种则需要较慢的水流。除了能量限制外，物种还受到生物相互作用的影响，如与生态相似物种的捕食和竞争。因此，只要有适当数量的食物资源和与其他物种的合理水平的相互作用，鱼类种群就会持续存在，这两个因素也受水流条件的调节。然而，流量特征和生物相互作用在决定鱼类物种多样性中的综合作用尚未得到很好的理解。该项目通过收集密苏里州东南部Meramec河系统多个地点的食物网数据，并将这些测量结果与河流流量特征联系起来，解决了这个问题。研究在不同水流状态下影响食物网结构的因素将为调节淡水河流生态系统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，代表了北美淡水生物多样性的热点。在梅拉梅克河及其支流中发现了120多种鱼类。同时，Meramec河为大约25万人提供饮用水。虽然流域地区仍然相对原始，但由于人类对景观的改变，一些河流路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大自然保护协会合作保护工作的主要焦点，因为它的生物重要性和人类对排水资源的依赖。本研究结果将为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保护生物多样性的努力提供实际应用。此外，几名本科生将接受研究技术方面的培训，并接触到有关水生资源保护的问题。

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.