9321549 Gulliver Lotic ecosystems are composed of an array of biological communities known o be heavily impacted by sediment loads originating from mining, forestry, and agriculture. To date, few controlled experiments have been conducted in which whole ecosystems are manipulated for the purpose of examining variable sediment load effects on ecosystem functioning. %%% Using eight constructed channels, a collaborative investigation will study different sediment load impacts on fish populations, primary producers,, benthic invertebrates, and microorganisms. This part of the project will evaluate models of sediment effects on light regimes, free stream turbulence and nutrient fluxes, as well as models of primary producer response to these factors. A primary objective is to improve the accuracy of productivity measurements by using modified enclosures that simulate channel hydrodynamic characteristics. In addition, photosynthesis, stream productivity and benthic respiration will be measured in each channel using the following techniques, respectively: oxygen and 14C measurements; light/dark bottles and diel surveys; benthic respirometer and microelectrodes. %%% Evaluation of sediment impacts on the above environmental factors and more accurate measurements of productivity should elucidate the lotic criteria which can protect stream communities from deleterious land management practices.
