Effects of Nutrient Enrichment on Stream Ecosystems
Approach & protocols:
The 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).
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