Stream Experiments

NEON will include a long-term experiment in streams arrayed across the continental U.S. Called the STReam Experimental Observatory Network (STREON), the experiment is designed to study how stream ecosystems respond to eutrophication (abnormally high additions of nutrients) and the loss of large consumers (fish or other large animals such as crustaceans, mollusks or insects). These two human influences are the most prominent forms of environmental change in freshwater ecosystems that are occurring in the modern era. The STREON experiment will:

  • Simulate chronic nutrient additions and the exclusion of large animals from 10 streams spanning the continental U.S. over a period of ~10 years (2-3 yrs of pre-experiment observations, 8 yrs of experiment).
  • Study how these two alterations to stream ecosystems change biologically essential processes (removal of nutrients, production of oxygen, decomposition of organic wastes) as well as the abundance and diversity of stream organisms.
  • Develop models that predict how the response of streams to environmental change varies in the major U.S. ecosystems – which differ in nutrient levels, temperature and hydrology.

The experiment will consist of an upstream control site (a NEON Aquatic site) and a downstream treatment site (a STREON site) that is dosed with additional nutrients. In the control and treatment sites, animals larger than ~1 cm will be excluded from small experiment baskets by electrified fences that emit a low-voltage shock. We will then measure changes in productivity and biogeochemical transformations that occur in streams in response to these stresses. We will collect samples of relatively large organisms (algae, insects, and fish) and those too small to be seen with the naked eye (microbes) to assess their responses to nutrient addition and large consumer removals.Draft STREON experiment schematic as of June 2013