Biogeographic and ecological influences on stream community composition in Zoar Valley, New York

Biotic communities in low order streams are influenced by multiple factors that may reflect both ecological conditions within individual watersheds, and also biogeographic considerations such as spatial proximity among streams and organism dispersal abilities. Our aim was to assess benthic invertebrate community composition in 23 first – third order streams in Zoar Valley, NY, across a gradient in habitat quality, and to further explore the role of local biogeography. Replicate Surber samples were collected from each stream on three dates during April – September 2006. Ninety-three taxa were collected, representing 58 families, dominated by juvenile insects. Additionally we quantified ecological variables such as stream order, watershed area, habitat quality indices, and land cover, and we generated a spatial distance matrix to quantify geographic separation among streams. Preliminary results suggest some taxa were highly variable in distribution, and thus may reveal factors contributing to community composition. We suspect the 23 encountered genera/species of Chironomidae may be particularly informative. Similarity/dissimilarity among stream communities will next be quantified by multivariate ordination of genus/species distributions, after which we will compare among stream distances in ordination space to geographic distances. Ultimately the completion of these analyses should enhance our understanding of the complex and dynamic ecology of small woodland streams, especially in a biogeographic context that has previously been under appreciated.