Ecological linkages between headwater streams and riparian and downstream habitats in the eastern Cascade Range, Washington, USA

Abstract

"I examined how headwater streams are ecologically linked with the terrestrial environment and upstream waters. I examined relationships between fish (rainbow and cutthroat trout), invertebrates, and habitat in 15 headwater streams in two ecoregions (wet, dry) and timber harvest scenarios (logged, unlogged) in the Wenatchee River sub-basin in the eastern Cascade Mountain Range, Washington state, USA. Fish biomass, density, and size were not related to ecoregion or to logging history. Invertebrate drift manipulations in 13 streams influenced fish movement (fish moved downstream in sites that were not supplemented with food) and diet (fish consumed less prey when drifting invertebrates were removed), but not fish growth or abundance. This study demonstrated that fish utilize drifting prey originating from upstream fishless waters, and that they are not able to compensate for the loss of this food. Headwater forest management may affect fish populations by altering prey resources where fish are food-limited"--Leaf iv