Nutrients such as nitrogen and phosphorus often limit production in aquatic ecosystems, but high levels of these nutrients lead to system degradation. Stream ecosystems in the Driftless Area of the Upper Midwest are especially vulnerable to nutrient pollution because of the high nutrient inputs to the region and because many of the streams have very high connectivity to the landscape through karst topography. Once in a stream ecosystem, downstream transport of nutrients is primarily a function of hydrology and biotic processes. This seminar will highlight several research studies exploring nutrient concentrations and the mechanisms of nutrient cycling in Driftless Area streams.