Land Use, Stream Habitat and Benthic Invertebrate Assemblages in a Highly Altered Iowa Watershed

Abstract

Abstract Knowledge of relationships between land cover (i.e., land use) and abiotic and biotic features of headwater streams enhances our ability to predict and effectively assess conditions in a variety of aquatic ecosystems. We evaluated land use effects on stream condition in an Iowa watershed dominated by intensive row crop agriculture and low- intensity urban development by quantifying relationships among land cover, stream invertebrate assemblages and other stream biophysical characteristics (i.e., invertebrate habitat) at 29 sites. On average, 81% of subbasin land cover was agricultural and 6% of land cover was urban across study sites. High nitrate concentrations (range = 5.6–29.0 mg/L) and high relative abundance of oligochaetes and chironomid midges reflected degraded conditions at all sites. However, agriculture and urban land use appeared to have different effects on stream features. Nitrate concentrations were positively related to agricultural land cover, and turbidity and nitrate concentr...