Half of the Earth's streams are intermittent: they occasionally dry or stop flowing. Since the 1980s, researchers who study streams have developed theories about how stream ecosystems work. Each theory is different, but they all focus on a single physical aspect of streams that is thought to best explain how stream ecosystem structure and function vary from one place to another. Physical factors that have been considered include stream size, floods, and climate. However, the body of work informing the development of these theories, and the body of work supporting them, is based on research from streams that flow continuously, or "perennial streams." Given that half of the Earth's streams are intermittent, there is a need to develop a new theory for streams that explains how drying acts as a control on stream ecosystem structure and function, how intermittent and perennial streams are different, and how those differences vary from region to region. This project uses macrosystems ecology as a foundation to develop and test such a theory that can be applied to all the Earth's streams. A smartphone app will map wet and dry stream reaches in conjunction with international research partners (1000 Intermittent Rivers Project), and citizen science organizers, and educational partners to create new teaching tools. The research may help inform decisions on water use where streams and intermittent and human populations are increasing. Seven graduate student will be included on the diverse research team.
This research project is comprised of three components. The first is a three-year field study of intermittent and continuously flowing streams in 10 different regions across the southern, central, and western US led by researchers at five different US universities that will collect streamflow and biological data. The field study will be focused on investigating how macroinvertebrate communities in intermittent and perennial streams differ in species composition and abundance, and how these differences vary according to climate. In 9 of the 10 regions, the researchers will use National Ecological Observatory Network (NEON) collected data, and sampling will follow NEON sampling protocols to generate NEON-compatible data. The second component will develop fine-scale hydrological models of the study watersheds using the Coupled Routing and Excess STorage (CREST) model. These models will predict where and when streams dry in these watersheds, and researchers will model streamflow patterns under different scenarios related to sea surface temperature oscillations and other changes. The third component of the project will generate spatial models that integrate the empirically collected ecological data in the field with the hydrological model outputs. This part of the project will investigate how large-scale climate oscillations (e.g. El Nino Southern Oscillation) influence regional drying patterns differently, and how shifts in spatial drying patterns influence stream ecosystems.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
