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Characterization and classification of invertebrates as indicators of flow permanence in headwater streams
FRITZ, K. M., B. R. JOHNSON, AND DAVID M. WALTERS. Characterization and classification of invertebrates as indicators of flow permanence in headwater streams. Presented at Society for Freshwater Science Annual Meeting, Louisville, KY, May 20 - 24, 2012.
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Headwater streams represent a large proportion of river networks and many have temporary flow. Litigation has questioned whether these streams are jurisdictional under the Clean Water Act. Our goal was to identify indicators of flow permanence by comparing invertebrate assemblages between perennial and temporary flow classes across a broad geographic area using taxonomic and species trait composition. We predicted trait composition would provide strogner discrimination between flow classes than taxonomic composition. Taxonomic composition was clustered primarily by region and subsequently by season and flow regime. In contrast to expectation, trait composition did not reveal consistent differences between flow classes. There were 37 and 21 indicator taxa (out of 1010) that were significantly associated with temporary and perennial reaches, respectively. Invertebrates from temporary reaches tended to have nonseasonal development, high crawling rate, and ability to survive desiccation, whereas those from perennial reaches were more often semivoltine with slow seasonal development and tended to be either herbivores, collector-filterers or shredders.