Benthic Macroinvertebrates in Logged and Unlogged Low-Order Southeast Alaskan Streams

The benthic macroinvertebrate communities of three low-order streams in southeast Alaska exhibiting pre- and post logging conditions were examined. The logged watersheds had the highest densities and biomass of benthic macroinvertebrates, while an unlogged coniferous climax forest watershed had the lowest. Benthic macroinvertebrate community composition was similar for key species among the three streams. Collector-gatherers were generally the most abundant functional group comprising up to 80% of the insect community; predator-engulfers were the second most abundant functional group. Salmonid fishes greatly altered the macroinvertebrate community composition during spawning because of mass disturbance of the streambed. Gravels disturbed during spawning were most rapidly recolonized by mayflies and stoneflies, especially Alloperla spp.