There is potential to apply nanotechnology to almost every economic sector, including consumer products, agriculture, biomedical, transportation and energy. While nanotechnology has the potential to produce societal benefits, it should be a priority to better understand the ecological risks from the release of nanomaterials (NMs) into the environment, including impacts upon ecological services. Our previous laboratory research has shown that NMs in the aquatic environment first affect organisms at the bottom of the food chain, including bacteria, algae and zooplankton. These responses may have devastating effects upon aquatic ecosystems by reducing overall productivity and altering the cycling of nutrients. There maybe compensatory mechanisms within aquatic ecosystems that mitigate these responses, but it is impossible to predict these responses using laboratory studies. We propose to conduct a study at the Experimental Lakes Area (ELA) in northwestern Ontario by adding nanoform silver to a small lake over two field seasons. Nano-silver is a widely used NM that is used as a bacteriocide in hundreds of products, including surgical bandages, food wrappers, baby bottles, slippers, socks, underwear, shoe-liners and even in washing machines. The nanoform silver will be added daily at a location along the lakeshore to simulate point source inputs from a wastewater treatment plant, and we will monitor the lake along an exposure gradient for changes to nutrient cycling and biological effects within the lake food chain. However, before starting the additions of silver, we will refine our approach by determining what happens in mesocosms (i.e. plastic tubes) that are deployed in lakes. ELA has been used for over 40 years as a living laboratory to study the effects of pollutants in the environment, including past studies of the impacts of pollution from phosphorus, acid deposition, mercury and endocrine disruptors. While we do not take lightly the potential impacts of nano-silver on the study lake in ELA, this approach is the only way to determine ecosystem level impacts. In turn, this information will influence regulatory policy to limit the ecological risks from the release of NMs into the environment.