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<br />Table 3. Summary of the number of zoobenthos and periphyton samples to be collected at <br />various spatial scales during each sampling trip. Number of habitats and the total number of <br />samples represent the maximum if all habitats are present and sampled in each strata. <br /> <br /> Zoobenthos Zoobenthos Periphyton Periphyton <br /> samples to samples to samples to samples to <br />River Strata Habitats Samples co llect process collect process <br />Colorado River 13 7 6 546 91 130 13 <br />Green River 10 7 6 420 70 130 10 <br />Yampa River 8 7 6 336 56 130 8 <br />White River 50 7 6 210 35 130 5 <br />Gunnison River 7 7 6 294 49 130 7 <br />------------------------------------------------------------------------------------------- <br />Total 43 35 30 1806 301 650 43 <br />· excludes Kenney Reservoir <br /> <br />Sampling Schedule <br /> <br />Initially, samples should be collected biannually, in early spring before upper basin runoff <br />and in fall after the summer thunderstorm season. This level of sampling intensity is a <br />compromise between monthly or quarterly sampling and annual sampling. Biannual sampling <br />should be adequate to provide sufficient information on taxonomic composition and <br />abundance to evaluate trends in invertebrate community responses to varying annual <br />hydrologic regimes. The times recommended for sampling represent two stable hydrologic <br />periods. <br /> <br />Field Methods <br /> <br />Sampling Locations <br /> <br />Sampling reaches and potential sampling locations should be delineated on a set of office <br />maps and a set of field maps. Actual locations selected to be sampled each trip should be <br />shown on both sets of maps. The exact location of each sampling location should be <br />determined in the field using a portable global positioning system (GPS) unit. <br /> <br />Zoobenthos and Organic Matter <br /> <br />Zoobenthos and benthic organic matter should be collected using the most appropriate <br />sampling device for each habitat (Table 4). Both quantitative and qualitative zoobenthos <br />samples should be collected. Quantitative samples should be used to evaluate changes in <br />abundance of the most common taxa. Methods may change as the study gets underway, <br /> <br />6 <br />