The invertebrate fauna of summer-dry streams in western Oregon

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