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Alteration of natural flow regimes by river regulation affects fish distribution and assemblage structure, but causative pathways are not always direct and may go unrecognized. The Colorado River population of the endangered Colorado pikeminnow, Ptychocheilus lucius, suffers from low rates of recruitment and reduced carrying capacity. We hypothesized that availability of prey fish for this large-bodied native piscivore may, in part, be limited by reduced standing crops of periphyton and macroinvertebrates resulting from accumulation of fine sediment in the riverbed. We stratified the 373-km-long study area into 11 strata and sampled various physical and biological parameters in runs and riffles of three randomly...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Colorado River,
Colorado pikeminnow,
Ecological Applications,
Ptychocheilus lucius,
benthic macroinvertebrates, All tags...
fish distribution,
flow regime,
foodweb,
interdisciplinary research,
natural-flow-regime paradigm,
river regulation,
river restoration,
sediment, Fewer tags
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Alluvial reaches of the Colorado River near Grand Junction, Colorado, provide important habitat for the endangered Colorado squawfish. This paper examines recent changes in the geomorphology of the Colorado River and addresses the question of what can be done to improve existing fish habitats. Observations of channel change during periods of above�average runoff from 1993 through 1995 indicate minor scour and fill of the main channel, but more significant scour and enlargement of side�channel and backwater habitats and flushing of fine sediment from the bed. Modeled relations between discharge and dimensionless shear stress т* indicate that the threshold of bed load transport (т* = 0.03) occurs at about half...
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