Effects of Nutrient Enrichment on Stream Ecosystems
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Approach & protocols:Study ApproachThe NEET study approach uses synoptic studies (objectives 1 and 2) and reach-scale, process-based studies (objective 3). For the synoptic study in each study unit, 30 independent, wadeable sites are selected along a gradient of nutrient conditions from within a specific agricultural setting. Sites are selected on the basis of geodata, predicted and measured nutrients, habitat, and stream size. Data collection during each single sampling period includes biological communities (algae, invertebrates, and occasionally fish), algal chlorophyll a, macrophyte cover, and stream habitat; primary production and respiration are determined at a subset of the sites. Nutrient samples are taken twice: a month prior to and during the biological sampling. In some study units a subset of sites are sampled seasonally to gain information on temporal variations as well as on variations along the nutrient gradient. Riparian and land-use data are obtained using GIS analytical procedures. For the reach-scale, process-based study (objective 3) in each of five study units, a single reach is examined for stream metabolism, nutrient cycling (transport, transformation, and retention), and surface water - groundwater interactions. Data and understanding developed from these studies will be used to develop predictive models and indicators that can be applied to unsampled streams in order to assess nutrient enrichment in the absence of site-specific data (objective 4). ProtocolsFitzpatrick, F.A., Waite, I.R., D'Arconte, P.J., Meador, M.R., Maupin, M.A., and Gurtz, M.E., 1998, Revised Methods for Characterizing Stream Habitat in the National Water-Quality Assessment Program: U.S. Geological Survey Water Resources Investigations Report 98-4052, 67 p. Johnson, M.R., and Zelt, R.B., 2005, Protocols for Mapping and Characterizing Land Use/Land Cover in Riparian Zones: U.S. Geological Survey Open-File Report 2005-1302-ONLINE ONLY, 16 p. Moulton, S,R., Kennen, J.G., Goldstein, R.M., and Hambrook, J.A., 2002, Revised protocols for sampling algal, invertebrate, and fish communities as part of the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 02-150, 75 p. Shelton, L.R., 1994, Field guide for collecting and processing stream-water samples for the National Water-Quality Assessment Program: U.S.Geological Survey Open-File Report 94-455. |