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Estimating biodiversity in desert aquatic habitats

Aquatic habitats are among the most imperiled habitats in desert ecosystems, yet they harbor a disproportionately high amount of biodiversity given the small land area they cover. Aquatic invertebrates constitute a major part of this biodiversity and form a critical part of the food web that sustains aquatic, riparian, and terrestrial organisms. Biodiversity in dryland aquatic habitats is strongly influenced by spatial and temporal variability, which presents challenges for predicting how management decisions could affect landscape-scale patterns of aquatic invertebrate biodiversity. With funding from the Dept. of Defense, this project integrates mathematical modeling, invertebrate sampling, and statistical estimation to develop methodologies for tracking biodiversity of aquatic invertebrates on military lands across the southwestern US.

Disturbance and the evolution of behaviors & life histories

Disturbance events such as flood, drought, fire, and disease outbreaks are powerful forces that can shape both the ecology and evolution of organisms. Flash floods are an extreme example of disturbance – in some desert streams flash floods remove over 95% of individuals. Some aquatic insects have evolved strategies for escaping flash floods: they sense the rainfall that often precedes floods and use this as a cue to temporarily abandon streams. CLICK HERE FOR VIDEOS and another page that describes flood escape behaviors in greater detail. Distinct populations of aquatic insects occupy streams with flood regimes ranging from mild (flash floods never occur) to wild (several scouring floods per year), so the potential for fine-scale natural selection is strong. We are using experiments and genetic techniques to determine how populations have evolved in response to these flood regimes, and whether populations can adapt to altered flood regimes due to climate change, dams, and other factors.

River management using prescribed flow regimes

Ecological effects of flow regime modifications (dams, diversions, channelization) on aquatic plants and animals (The Nature Conservancy, US Fish & WildlifeService), including whole-river experiments on the Bill Williams River, Arizona.