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Effects of reservoir connectivity on stream fish assemblages in the Great Plains

TitleEffects of reservoir connectivity on stream fish assemblages in the Great Plains
Publication TypeJournal Article
Year of Publication2006
AuthorsFalke, JA, Gido, KB
JournalCanadian Journal of Fisheries and Aquatic Sciences
Keywordscommunity structure united-states flow regime river fragmentation upstream america variability patterns

The upstream effects of reservoirs on stream fish assemblages were highly localized in 3rd- through 5th- order streams in the Great Plains, USA. Streams that differed in connectivity to reservoirs were sampled at their confluences with a river or reservoir and between the confluence and the stream's origin. Sites at confluences had higher total, normative, and reservoir species richness than middle sites. Variability in fish assemblage structure upstream of reservoirs was influenced by catchment area, stream size, gradient, and reservoir connectivity. Confluence sites connected to reservoirs were correctly classified based on the presence of red. shiners (Cyprinella lutrensis) and bluntnose minnows (Pimephales notatus) and the absence of sand shiners (Notropis stramineus); middle sites on connected streams were classified by the absence of redfin shiners (Lythrurus umbratilis). Intensive sampling across pool habitats within two streams isolated by a reservoir indicated that abundance of common reservoir species was related to pool size, turbidity, and canopy cover, but not proximity to the reservoir. These data suggest that streams connected to reservoirs can maintain diverse native fish communities with minimal invasions by reservoir-dwelling species, but a fraction of the community either has been lost or occurs at low abundance (e.g., sand shiners and redfin shiners).

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