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7/14/2009 5:02:34 PM
Creation date
5/17/2009 11:25:25 PM
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UCREFRP
UCREFRP Catalog Number
9297
Author
U.S. Geological Survey.
Title
Algal Data From Selected Sites in the Upper Colorado River Basin, Colorado, Water Years 1996-97.
USFW Year
2001.
USFW - Doc Type
00-266,
Copyright Material
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<br />Periphyton microhabitats in DTH environments <br />include areas within the stream reach that mainly <br />support periphyton associated with stream deposi- <br />tional zones. The DTH habitats in the UCOL study <br />unit consist of slow-water areas, such as pools, that <br />typically contain organically rich, fine substrates. <br />Quantitative DTH periphyton samples were collected <br />from the surficial (5-7 mm) layer of epipsammic <br />(coarse streambed sediments) and epipelic (fine stre- <br />ambed sediments) microhabitats in depositional zones. <br />One-half of a 47-mm, plastic petri dish was gently <br />pushed into the streambed sediment to collect DTH <br />periphyton samples. A small stainless-steel spatula <br />was slipped under the petri dish to seal the algal <br />sample inside the petri dish. The sealed petri dish was <br />lifted from the stream bottom and briefly agitated <br />(below the water surface) to remove excess sediment; <br />then the sample was rinsed with stream water to <br />transfer the sample to a container. Five DTH samples, <br />each from a different depositional zone, were collected <br />and compo sited to make one representative sample for <br />the site. The periphyton sample was preserved onsite <br />with a 3- to 5-percent concentration of formalin solu- <br />tion. The DTH samples were sent to the USGS NWQL <br />in Arvada, Colorado, for quality-assurance and <br />quality-control processing, and then samples were <br />shipped to the ANSP in Philadelphia, Pennsylvania, <br />for identification and enumeration. <br /> <br />Calculation of Biovolume Data <br /> <br />Algal biovolumes were not reported by the labo- <br />ratory if the algal taxa represented less than 10 percent <br />of the entire algal sample. Biovolumes not reported by <br />the laboratory were determined using the following <br />formula: <br /> <br />Biovolume (/lm3/cm2) = <br />density (cells/cm2) x <br />biovolume per cell (/lm3/cell) <br /> <br />The cells-per-square-centimeter values were <br />provided as part of the algal community data for each <br />sample. Biovolume-per-cell values were obtained <br />using data from other UCOL-NAWQA algae studies, <br />other NAWQA study unit data, and measured refer- <br />ence images, or values were determined from litera- <br />ture size ranges (Frank Acker, Academy of Natural <br />Sciences of Philadelphia, written commun., 2000). <br /> <br />Quality Assurance/Quality Control <br /> <br />Quality-assurance and quality-control (QA/Qc) <br />procedures include field-replicate and laboratory anal- <br />ysis procedures to determine the variability associated <br />with sample collection, processing, handling, and <br />analysis. RTH field-replicate (replicate) samples were <br />collected in the same stream reach as environmental <br />samples at five selected sites (about 17 percent of the <br />total number of samples) for the 2-year sampling <br />period. Periphyton population density and community <br />composition among environmental and replicate <br />samples were used to compare variability at these <br />sites. USGS NWQL laboratory QA/QC followed <br />procedures described in Porter and others (1993). <br />Laboratory QA/QC for samples processed at the <br />ANSP implemented standard operating procedures, <br />sample recounts, and taxonomic consistency for <br />periphyton samples (Frank Acker, Academy of <br />Natural Sciences of Philadelphia, oral commun., <br />2000). <br />The relative percent difference (RPD) between <br />the environmental and replicate samples was calcu- <br />lated using the formula: <br />RP D = Sample 1 - Sample2 x 100 <br />eamPlel; sample2) <br /> <br />Relative percent difference calculations were <br />based on the total density and total biovolume for the <br />sample (table 2). The largest RPDs occurred in small <br />streams and ranged from 135 to 197 percent between <br />the environmental and replicate samples. Total density <br />and biovolume RPDs were 50 percent or less in the <br />larger streams and rivers. <br />Quality-assurance and quality-control results <br />(table 2) for the RTH periphyton samples indicate that <br />the largest sampling variability tends to occur in <br />samples from small streams. The stream-channel <br />geomorphology (streambanks and stream bottom) of <br />the small stream sites (figure 1; sites 1 and 2) was less <br />uniform, and changes occurred within shorter <br />distances across the stream reach than at the large river <br />sites (figure 1; sites 9, 11, 15). Sample variability may <br />increase due to differences in stream conditions at <br />small stream and large river sites. Differences in mean <br />stream depth, stream elevation, mean streamflow <br />(table 1), and other growth-limiting factors related to <br />stream size may cause changes in the periphyton <br />community composition at these sites. <br /> <br />METHODS OF DATA COLLECTION 5 <br />
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