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1 August 2017 Associations of Channel Form with Spawning Riffle Quality and Macroinvertebrate Assemblages in Small Restored Spring Creeks of Western Montana
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Abstract

Spring creeks are highly prone to degradation from anthropogenic (e.g., grazing-related) sediment, yet little is known to guide sediment reduction through restoration. This long-term study explored associations of basic channel form with riffle substrates and trout spawning site quality, along with nine macroinvertebrate taxa groups and two biotic indices in four actively restored (reconstructed with > 10 years rest from livestock grazing) and four unrestored (damaged by land use, including riparian livestock grazing) spring creeks in western Montana. Despite no change in channel slope, riffles in restored streams had lower width-to-depth ratios (10.2 ± 1.8 versus 19.2 ± 4.6), higher velocities (0.71 ± 0.18 versus 0.39 ± 0.09 m/s), lower percentage of sediment < 6.3 mm (25.9 ± 6.6 versus 41.4 ± 6.2) and higher quality spawning sites than unrestored streams. These results suggest stream restoration can improve spawning substrate by facilitating sediment transport via reduced width-to-depth ratio. When all streams were considered, the richness of sediment-tolerant macroinvertebrates were inversely correlated with riffle substrate size; whereas, clinger (sediment-intolerant) richness correlated positively with riffle substrate size. Of the two biotic indices, the Montana Mountains and Foothills Biotic Index showed no correlation to the nine taxa groups. Whereas, a significant correlation of the Fine Sediment Biotic Index with sediment < 6.35 mm suggests it may be a better indicator of spring creek habitat integrity and restoration effectiveness.

© 2017 by the Northwest Scientific Association. All rights reserved.
Ron Pierce, Craig Podner, and Sean Sullivan "Associations of Channel Form with Spawning Riffle Quality and Macroinvertebrate Assemblages in Small Restored Spring Creeks of Western Montana," Northwest Science 91(3), 283-300, (1 August 2017). https://doi.org/10.3955/046.091.0308
Received: 26 August 2016; Accepted: 1 May 2017; Published: 1 August 2017
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