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r� Table 2. Stream taxa identified in macroinvertebrate samples collected in the North Fork of the <br />Gunnison River east of Somerset, Colorado. <br />�laSS Order Family Genus <br />Acarina Hydrocarina <br />(Water mites) <br />Insecta Coleoptera Elmidae (Diving beetles) <br />(Beetles) <br />Diptera Chironomidae (Midges) <br />(True flies) Empididae (Dance flies) <br />Ephemeroptera Baetidae Baetis <br />(Mayflies) Ephemerellidae Drunella grandis <br />Serratella <br />Heptageniidae <br />Leptophlebiidae Paraleptophlebia <br />Plecoptera <br />Perlidae <br />Claassenia sabulosa <br />(Stoneflies) <br />Perlodidae <br />Isoperla <br />Pteronarcyidae <br />Pteronarcella <br />Trichoptera <br />Brachycentridae <br />Brachycentrus <br />by rus <br />(Caddisflies) <br />Hydropsychidae <br />Hydropsyche <br />Lepidostomatidae <br />Lepidostoma <br />Leptoceridae <br />Oecetis <br />Counts of macroinvertebrates in the individual replicate samples ranged from 76 at station U2 <br />in October to 663 at station D1 in March. Abundance estimates of the four major <br />macroinvertebrate orders (Ephemeroptera, Plecoptera, Trichoptera, and Diptera) at the sample <br />stations ranged from 327/m2 (station U2) to 1617/m2 (Station U4). These four orders typically <br />accounted for over 80 percent of the total macroinvertebrate population. The most common <br />organisms were Brachycentrus caddisfly larvae, Serratella mayfly nymphs, and chironomid <br />larvae. In late summer, rocks at the edge of the channel were covered with thousands of <br />Brachycentrus cases. Particularly conspicuous in the samples were the relatively large <br />predaceous nymphs of the stonefly Claassenia sabulosa, which often approached 3 cm in <br />length. Appendix 2 contains all of the count data from the samples that were collected in <br />March and October. <br />9 <br />1`4• <br />