Small headwater streams are a critical freshwater resource in the agriculturally-dominated landscape of the Midwestern US, yet are understudied relative to more pristine aquatic ecosystems. Agricultural practices that remove natural streamside vegetation may change the energy base that fuels ecosystem processes. Crop byproducts (e.g., non-harvested foliage) may represent a dominant carbon source in agriculturally-influenced headwater streams. The role of this novel carbon source to stream ecosystem function has not been determined. We will quantify input, standing stocks, decomposition and transport of corn foliar detritus and pollen in 18 streams across the Midwest.
In 2000, approximately 28 million hectares of corn were planted in the North American corn-belt, with 18% of this area planted with Bt corn. Because the Bt d-endotoxin is produced throughout the plant, dispersing pollen and non-harvested foliage that enters agricultural streams may be consumed by various aquatic organisms, and thus pose a threat to the environment. The potential effect of genetically modified crops on non-target species in aquatic ecosystems has received little attention, and consideration of headwater streams as a mechanism for the unintended dispersal of Bt d-endotoxin through the environment has been overlooked. We will determine if Bt d-endotoxin is present in the food web and affecting aquatic biota. Bt corn foliar detritus may detrimentally influence aquatic organisms and energy flow in streams, and merits further study.
