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We investigated spatial variability in the community structure of stream macroinvertebrates at six reaches within Caribou-Poker Creeks Research Watershed in the Alaskan taiga forest. Stream reaches differed most notably in river continuum position (stream orders 1–4) and influence of permafrost. Permafrost may underly much of an entire watershed or may be only locally present in valley bottoms. Permafrost distribution influences hydrology, water temperature, and riparian vegetation. We sampled benthic macroinvertebrates six times during the ice-free season between June 1995 and June 1996. Mean invertebrate abundance (range: 1160–14494 individuals/ m2) was significantly different among sites, the lower values occurring...
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We examined the spatial distributions of Alaskan freshwater fishes using 2 frameworks, ecoregions and hydroregions (catchments). Ecoregions are defined by climate, terrain, vegetation, and soils; their utility in explaining distributions of aquatic organisms is based upon terrestrial-aquatic linkages. Analysis of the probable dispersal of aquatic organisms along past and current hydroregions provides an alternative and likely complementary path to understanding distributions of aquatic organisms. We use published distribution records for freshwater fishes of Alaska to construct a matrix of presence/absence records for each fish species in ecoregions and hydroregions of Alaska. We assessed faunal similarities among...
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