The invertebrate fauna of summer-dry streams in western Oregon

Abstract

In this paper we report on invertebrate communities and habitat associations of species in summer-dry streams of western Oregon. Overall, we recorded 202 aquatic and semi-aquatic species, including at least 13 previously undescribed taxa. Species richness in temporary forest streams (≥125 species) exceeded that in a permanent headwater (100 species). Richness in ephemeral streams was 35 species or less. Duration of flow, exposure (shaded or open), riffle-pool structure and summerdrought conditions were key factors shaping community composition between and within stream types. We conclude that the potential of summer-dry streams with respect to habitat function is still widely underestimated. Such systems need more attention both from limnologists and landscape ecologists.