COLLABORATIVE RESEARCH: Temporal stability of riverine communities in dendritic networks at multiple spatial scales

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Understanding how communities of species change through time is one of the fundamental goals of ecology. A key step toward understanding how natural systems function is answering two questions: 1) Why are some communities more sensitive to disturbance than others? and 2) Can the sensitivity of a community be predicted based on its location in a landscape? This study seeks to understand how communities develop and are maintained in rivers. Specifically, the project will explore how sensitivity of river communities is affected by environmental features that dictate how organisms move about the landscape. Examples of these environmental features include prevailing wind currents, connections between forest fragments, and the shape of a river and the small streams feeding the river (i.e., river network) in a watershed. This project uses stream invertebrates in river networks as a model system. The work involves three major tasks: 1) To analyze how the shape of a river network affect the level of variability of stream invertebrate communities using existing data. 2) To experimentally test how the structure of river networks affects the response of invertebrate communities to disturbances. This task will be accomplished using experimental streams, experimentally inducing a disturbance, and following the response. 3) To produce a computer model to explore scenarios considering different shapes of networks, different types of organisms and novel disturbances that cannot be explored using existing data or experiments. This work will directly inform scientists and managers about the responses of river systems to disturbance. The study will also create a tool for exploration of networks in new river systems. This study will provide training for graduate and undergraduate students in ecology and mathematical modeling. Linking community stability to spatial processes in variable environments is one of ecology's remaining great challenges, with implications for the management and conservation of biodiversity. The researchers focus on controls over invertebrate community stability in riverine ecosystems because they have found that a site location in a dendritic stream network can influence both local biodiversity and temporal stability. Therefore, this project addresses the general question: How does location of a community within a dispersal network interact with species traits to affect aggregate and compositional community stability? Ultimately this work will be directed at three specific questions: (1) Within a dispersal network, how does location affect the temporal stability of communities? (2) How resilient are communities at different locations within a network? (3) How does local stability and structure of the dispersal network affect stability at the regional scale, i.e., across the entire dispersal network? The work will build on existing projects including the ecology of river networks, analysis of community temporal stability, river network modeling, and the interaction between models and field data. The project will employ several techniques to address the question, including a meta-analysis of archived long-term stream monitoring data, field experiments, and mechanistic modeling to achieve an understanding of processes behind observed compositional and aggregate stability. This will simultaneously provide a general theoretical underpinning that is transferable to other contexts and systems.