Macroinvertebrate Communities of Non-Glacial Alpine Streams in Western North America’s Coast Mountains

Alpine streams are particularly vulnerable to climate change and in many parts of the world are poorly studied, which is true of western North America. We sampled the invertebrate communities and measured the physico-chemical parameters of nine small streams in a single alpine meadow. There was a wide variation in the physico-chemical variables in this single, small catchment. Three variables were selected based on their high loadings from principal component analysis, and these were slope, width and pH. There were relations between densities of some of the benthic organisms and the three main environmental gradients. We found large variation in densities (595 to 7340 individuals m−2) and diversity of benthic communities across a small gradient of physico-chemical variation in these nine streams in a single alpine meadow. High beta diversity (most > 0.8) between streams indicated substantial differences in community structure and diversity in a small area of about 1 km. These results suggest strong environmental filters on communities in these alpine stream systems and the potential for high regional biodiversity far beyond what individual streams support.