Seasonal species composition of invertebrates in several Oregon streams.

Abstract

The invertebrate communities ofeight Oregon streams were sampled seasonally from 1974 to 1976. Benthic, drift, and two types of aerial-trap samples were collected. Occurrence and percentage composition are summarized by sample type, season, and geographic area (coastal, Cascade, central, and eastern Oregon). Within 276 families, 426 taxa were identified; the 20 families most prevalent within each sample type accounted for the majority of organisms collected (77.8-91.8 percent). In most areas and seasons, Diptera and Ephemeroptera together comprised over half of the invertebrates collected.