Research Themes

Biodiversity, disturbance, and dispersal in streams and riparian areas

Our research focuses on how disturbance and dispersal processes shape local population, community, and metacommunity patterns in streams and riparian areas. We're most interested in how life-history traits of aquatic and riparian organisms (e.g., dispersal modes) interact with stream flow variability to produce the highly-diverse communities that often we find in and alongside streams. Understanding these interactions is critical in the face of altered flow regimes resulting from climate change and anthropogenic water withdrawals, especially in desert and semi-arid regions.

Current research projects:

Drought and water use shapes aquatic biodiversity in streams

Drought is currently one of the most pressing environmental stressors in the Southwest and in many regions of the world. Multi-year droughts combined with societal needs for freshwater are causing streams to dry and reservoir levels to reach historic lows. Much of our research focuses on quantifying the effects of drought on biodiversity in streams in the western United States and northwestern Mexico.

Press coverage:

Collaborative opinion piece:

Novel aquatic ecosystems in the Anthropocene

Drought and groundwater extraction have caused the loss of stream habitat in many parts of the world, especially in arid and semi-arid regions. However, in some places, treated wastewater is being discharged into dry riverbeds, re-creating those historical habitats. These novel effluent-dominated streams look similar to historical habitats, at least superficially, but are they really the same? What challenges do colonists to these novel ecosystems face? And can we reconnect human communities with their local rivers to foster a watershed conservation ethic and avoid further habitat loss?

Press coverage:


Terrestrial-aquatic linkages and ecosystem dynamics in and alongside drying streams

Drought and stream drying not only affect the diversity of species in a stream, but also myriad food web and ecosystem dynamics, both in streams and in adjacent terrestrial ecosystems. Shrinking aquatic habitats and altered riparian vegetation caused by extreme drought and water use could impact aquatic food webs that support imperiled species. We are currently working on projects addressing (1) how stream drying and the loss of aquatic subsidies may affect riparian lizards and (2) how stream drying may alter food web dynamics and population connectivity for endangered mud turtles.

Press coverage:


Current collaborative projects:

The Dry Rivers Research Coordination Network is an NSF-funded project to link researchers studying intermittent rivers and ephemeral streams around the globe. We are organizing a series of expert workgroups that will synthesize the growing body of research on intermittent river hydrology and ecology. These workgroups will produce generalized frameworks that can explain how intermittent river hydrologic and ecologic systems work. This research is important because intermittent rivers are often overlooked or excluded from water management plans due to uncertainty about their hydrologic and ecological importance.

Follow our RCN on Twitter @DryRiversRCN and find more project information on our website.

StreamCLIMES is an NSF-funded collaborative research project with Dan Allen at University of Oklahoma, Katie Costigan at the University of Louisiana Lafayette, Meryl Mims at Virginia Tech, Ben Ruddell and Abe Springer at Northern Arizona University, Albert Ruhi at the University of California Berkeley, Robert Pastel at Michigan Tech University, and Tom Neeson and Yang Hong at the University of Oklahoma.


Together we will conduct one of the first coordinated projects to investigate how drying affects stream ecosystems in different climates across the southern half of the US. The work includes a significant field based component that integrates NEON stream research sites, where we will document the biodiversity, food web structure, and genetic connectivity of stream benthic invertebrate communities at perennial (continuously flowing) and intermittent (non-continuously flowing) stream sites. We will also develop a smartphone app designed for researchers and citizen scientists to map wet and dry reaches of streams and rivers. Later phases will include developing hydrological models that will predict stream drying patterns in the study river systems under different climate scenarios including climate oscillations and climate change, and spatial ecological models that will integrate field-collected data and hydrological model outputs to project how stream ecosystems will respond to large scale climate variability. This project is funded by the National Science Foundation Macrosystem Biology program and will run from 2019-2023.

Follow our StreamCLIMES project on Twitter @streamCLIMES