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1 <br />• densities decreased from 5328/m2 at Station 1 to 1875/m2 at Station 3 followed <br />by a large increase to 12251/m2 at Station 4. The oligochaete Limnodrilus <br />dominated the pool fauna at Station 1 (Fig. 3) with Palpomyia, Chironomidae <br />Form 1 and the amphipod H lella azteca also abundant. The lower density at <br />l Station 2 was due to fewer dipterans and worms. Densities at Station 3 were <br />lower than Station 2 due to decreased abundance of Limnodrilus (Fig. 3), <br />although mayflies and dipterans exhibited increased density. Highest densities <br />were found at Station 4, due primarily to larger numbers of worms and especial- <br />ly chironomids. Neither caddisflies (Trichoptera) nor stoneflies (Plecoptera) <br />were collected in Foidel Creek. <br />Total number of species closely followed the pattern of the Coleoptera <br />taxa (Fig. 4). The lower numbers of taxa at Station 2 and 4 was due to a lack <br />of beetles collected at these stations. The highest number of species was <br />i found at Station 3, resulting from the large number of species of diving beetles <br />11 (Dytiscidae). Number of dipteran taxa remained low at all stations. The <br />species diversity index (D) was also highest at Station 3, although it was <br />generally low at all stations reflecting the stressful conditions inherent in <br />intermittant streams. <br />TABLE 2: Species List, mean density (numbers/m2) and diversity values of <br />{ benthic invertebrates from Foidel Creek, Routt County, Colorado, <br />t August 1980. <br />!. STATIONS <br /> 1* 2* 3* 4 1 2 3 4 <br /> TAXA Riffle Pool <br /> INSECTA <br /> Ephemeroptera (mayflies) <br />' Callibaetis 38 97 -- 344 366 <br /> Diptera (true flies) <br /> Palpomyia 16 1237 86 -- 129 <br />L Chironomidae Form 1 2039 409 290 581 6760 <br /> Chironomidae Form 5 -- -- -- 11 -- <br /> <br />1 Chironomidae Form 8 285 -- -- 97 560 <br /> -9- <br />