The primary goal of my research is to understand how natural and anthropogenic factors influence the structure and function of aquatic ecosystems. The research questions I focus on are the result of my interest in a particular ecosystem: California's Sierra Nevada. Despite the critically important ecosystem services provided by this mountain range to millions of people and its proximity to dozens of universities, aquatic ecosystems of the Sierra Nevada remain relatively poorly understood. This lack of understanding undermines our ability to restore ecosystem structure and function and to anticipate how these ecosystems will respond to future stressors.
In recent years, my colleagues and I have conducted research on a wide range of topics, including the impact of nonnative fish (trout) on native fauna and on ecosystem processes, the role of introduced trout in altering connections between lake and terrestrial ecosystems, lake recovery following trout removal, rapid evolution in invertebrates following the introduction of trout into naturally fishless lakes, population genetics of lake-dwelling amphibians, invertebrates, and fungi, effects of habitat conditions and fish stocking on the structure of native and nonnative trout populations, and the role of introduced fish, agricultural pesticides, ultraviolet radiation, and disease in driving the decline of amphibians. I am also interested in the taxonomy of the native species that inhabit Sierra Nevada lakes, a considerable number of which remain undescribed.