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Abstract

From 1984 to 1986, the Arkansas Highway and Transportation Department reconstructed and upgraded a portion of St. Hwy. 123 west of St. Hwy.7 at Pelsor, Arkansas. As a result of the construction, portions of Haw Creek, Johnson County, Arkansas, a third order stream in the Boston Mountains Ecoregion, were straightened and channelized. In reconstructing specific stream reaches, stream banks were riprapped and vegetated, gabions constructed and positioned, stream substrates and pool-riffle ratios altered. Instream and riparian habitat and fish biomass and diversity in altered reaches were radically altered. Channelized reaches became wide and shallow, lacking overstory cover and pools. Substrate particle size changed from boulder/rubble to rubble/gravel/sand and velocity increased. Fish communities in channeled reaches simple; Campostoma anomalum, Notropis boops, and Etheostoma spectabile accounted for more than 80 percent of all fish captured. This represented a shift from piscivore and insectivorepiscivore to herbivore and insectivore dominated feeding guilds. Natural channel reaches had more complex fish communities and greater abundance of centrarchids and ictalurids, primarily deeper water groups. Immediately after channelization, altered reaches had a larger biomass than natural reaches (0.43-0.26 g/m^2 ). The summer following alteration, channeled segments were basically dewatered, and biomass decreased dramatically (0.06-0.1 1 g/m^2). One year post channelization, altered reaches had eroded, scoured and deepened at their headwaters, and embedded. Fish community composition in altered reaches s stabilizing to a riffle-type assemblage dominated by the herbivore Campostoma anomalum.

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