A major challenge for ecologists is to understand how populations respond to disturbances in their physical environment. Mathematical models can advance such understanding by giving added value to previous empirical work and helping identify priorities for future studies. This research will develop new theory applicable to plant and animal populations in streams, rivers, and other media where flow is biased in one direction. The project will focus on three questions. By what mechanisms does environmental variability impact the likelihood of extinctions? What is the short-term effect of river flow on population responses to disturbances? And how do interactions among species influence the response of populations and communities to environmental stress, such as changes in flow or addition of nutrients? The utility of the new theory will be tested using data from experimental stream systems, and also from a natural river.
The findings will provide environmental mangers with new approaches to the critical issue of ''instream flow needs'': the flow of water in a river that must be maintained to ensure viability of resident biota. There will be cross-disciplinary training for a post-doctoral researcher, a graduate student, and for both ecology and mathematics undergraduates.
