Are trout populations affected by reach-scale stream slope?

2000 ◽  
Vol 57 (2) ◽  
pp. 468-477 ◽  
Author(s):  
Daniel J Isaak ◽  
Wayne A Hubert
Keyword(s):  
Species Composition ◽  
Spatial Scale ◽  
Relative Abundance ◽  
Cross Sections ◽  
Fish Habitat ◽  
Rocky Mountain ◽  
Mountain Streams ◽  
Habitat Models ◽  
High Slope ◽  
Rocky Mountain Streams

Reach-scale stream slope and the structure of associated physical habitats are thought to affect trout populations, yet previous studies confound the effect of stream slope with other factors that influence trout populations. We isolated the effect of stream slope on trout populations by sampling reaches immediately upstream and downstream of 23 marked changes in stream slope on 18 streams across Wyoming and Idaho. No effect of stream slope on areal trout density was observed, but when trout density was expressed volumetrically to control for differences in channel cross sections among reaches in different slope classes, the highest densities of trout occurred in medium-slope reaches, intermediate densities occurred in high-slope reaches, and the lowest densities occurred in low-slope reaches. The relative abundance of large trout was reciprocal to the pattern in volumetric trout density. Trout biomass and species composition were not affected by stream slope. Our results suggest that an assumption made by many fish-habitat models, that populations are affected by the structure of physical habitats, is at times untenable for trout populations in Rocky Mountain streams and is contingent upon the spatial scale of investigation and the population metric(s) used to describe populations.

Characteristics and function of large woody debris in subalpine Rocky Mountain streams in northern Colorado

1995 ◽  
Vol 52 (8) ◽  
pp. 1789-1802 ◽  
Author(s):  
Ann D. Richmond ◽  
Kurt D. Fauseh
Keyword(s):  
Pacific Northwest ◽  
Woody Debris ◽  
Fish Habitat ◽  
Rocky Mountain ◽  
Large Woody Debris ◽  
Mountain Streams ◽  
Coastal Forests ◽  
The Pacific ◽  
And Function ◽  
Rocky Mountain Streams

Large woody debris has been well studied in coastal forests of the Pacific Northwest, but little is known of its role in Rocky Mountain streams. Large woody debris was measured in 11 undisturbed streams draining subalpine old-growth forests in north central Colorado to assess abundance, characteristics, and function. Although large woody debris in Colorado had smaller diameter, length, and volume than in the Pacific Northwest, its abundance and function were similar. The majority of pools (76%) were plunge and dammed pools formed by large woody debris, most of which spanned the channels perpendicular to stream flow. Smaller streams had a greater proportion of such perpendicular pool-forming pieces than larger streams. Four disturbed streams had significantly less and smaller large woody debris than undisturbed streams. Flows in larger undisturbed streams were capable of moving large woody debris, so pieces were more often located at the stream margins, oriented diagonally, or distributed in clumps than in smaller streams. Individual pools were larger and deeper in larger streams, but their size was not related to the size of large woody debris pieces forming them. Therefore, the function of large woody debris in forming fish habitat in small Rocky Mountain streams is strongly influenced by the stream's location within the watershed.

Responses of Epilithic Algae to Regulation of Rocky Mountain Streams

1987 ◽  
pp. 383-390 ◽  
Author(s):  
R. G. Dufford ◽  
H. J. Zimmermann ◽  
L. D. Cline ◽  
J. V. Ward
Keyword(s):  
Rocky Mountain ◽  
Mountain Streams ◽  
Epilithic Algae ◽  
Rocky Mountain Streams

scholarly journals A Study of the Aquatic Insects of Two Rocky Mountain Streams in Grand Teton National Park

1979 ◽  
Vol 3 ◽  
pp. 12-20
Author(s):  
Donald Bennett
Keyword(s):  
Aquatic Insects ◽  
National Park ◽  
Rocky Mountain ◽  
Mountain Streams ◽  
Ecological Disturbance ◽  
Grand Teton National Park ◽  
Future Studies ◽  
Physical Data ◽  
Systematic Collection ◽  
Rocky Mountain Streams

An investigation of the insect faunas of Pilgrim and Pacific Creeks was carried out for comparison and contrast of the two streams. The possibility of placer mining at Pacific Creek emphasized the need of the study at this point in time. Systematic collection of insects and physical data from the streams provide information on habitats which are essentially unaltered by man. It is hoped that this research will form the groundwork for future studies and provide data for reference in the event of ecological disturbance of either habitat.

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