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

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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.