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<br />14 <br /> <br />Table 1. - Percent comparison of metric values indices to reference station and scores ( ). <br />Arkansas River data July 1991. <br />Comparison value <br />Below LMDT (C) below <br />freshening inflow (D) <br />C D <br /> <br />Metricl <br /> <br />Above LMDT (A and B) <br />A B <br /> <br />Taxa richness 4% (6) 0% (6) 35% (4) 19% (6) <br />EPT index 94% (6) 100% (6) 69% (0) 81 % (4) <br />DlC-5 4 (6) 5 (6) 1 (1) 2 (4) <br />% Contribution of dominant taxon 33% (2) 30% (4) 37% (2) 28% (4) <br />Community loss index 0.24 (6) 0.00 (6) 0.82 (4) 0.48 (6) <br />Scrapers/scrapers + fill' 0.923 (6) 1.000 (6) 0.545 (4) 0.136 (0) <br />Baetis/total Ephemeroptera 0.35 (4) 0.45 (4) 0.72 (2) 0.67 (2) <br />Shredder taxa 100% (6) 100% (6) 0% (0) 50% (4) <br />Total score 42 44 17 30 <br />Score relative to reference station 95% 100% 39% 68% <br /> nonimpaired nonimpaired moderately slightly <br /> impaired impaired <br /> <br />1 Taxa richness - the mnnber of taxa present in a community as an indication of community health. <br />EPT index - The total number of distinct taxa within the orders Ephemeroptera, Plectoptera, and Tricoptera. <br />DlC-5 - Dominants in common is the similarity of study stations to reference stations based on the identity <br />of the five most abundant taxa. <br />% contribution of dominant taxon - The percent contribution of the numerically dominant taxon to the total <br />number of organisms. <br />Community loss index - The loss of benthic taxa between a reference station and the study stations. <br />Scrapers/scrapers + filter collectors - This is the ratio of scraper organisms to scraper and filtering collectors <br />functional feeding groups. This index reflects the riffle-run community food-base. <br />Baetis/total Ephemeroptera - The ratio of the pollution tolerant mayfly genus Baetis to other members of the <br />order Ephemeroptera. <br />Shredder taxa - Based on the functional feeding group concept, the presence of shredder group taxa allows <br />evaluation of impairment relative to the CPOM (course particulate organic matter) present in the river. <br />Total score - This is a summation of the ranking scores developed by the EP A and others for use with these <br />~~ ~ <br />Score relative to reference station - The total scores are compared with those from site B which in this study <br />is considered the most undisturbed site. Relative impairment is based on the total scores. <br /> <br />... <br />