The Effects of a Sandtrap on the Trout Habitat of Bear Creek

Knsty A. Cowdin
School of Science and Natural Resources
Lake Superior State University

Abstract

	A sandtrap is a basin excavated in a portion of a stream to collect sand
bedload as it moves downstream. This usually results in scouring out gravel
and cobble substrate downstream of the basin thus benefiting trout by creating
spawning ground and providing a suitable habitat for those aquatic insects on
which trout feed. The objectives of this study were to note any change in
density of aquatic insect feeding guilds in the two sites and to determine if the
sandtrap is effective in improving the habitat downstream of the basin in Bear
Creek. In the Fall of 1995, a Surber Sampler was used to collect eight
samples of aquatic insects above and below the sandtrap. The results of a
Mann-Whitney U Test show a significantly greater density of scrapers and
collectors occurring downstream of the sandtrap. A Mann-Whitney U Test
revealed that the densities of Ephemeroptera, Plecoptera and Tricoptera
(EPT) and the total insect densities were greater downstream of the sandtrap.
Feeding guilds of aquatic insects are an excellent indicator of stream habitat.
The EPTs are very sensitive to changes in sand bedload. Bear Creek showed
a decrease in sand bedload downstream of the basin and the EPT densities
were prominent in that section. The conclusions of this study indicate that the
densities of insect feeding guilds varied as a result of the decreased sand
bedload and the overall trout habitat was greatly improved as revealed by the
significantly greater EPT and total insect densities along with an improved
stream morphology downstream ofthe sandtrap.

Selected References

Alexander, G. Dunn, W and Hansen, E. 1982. Sand Sediments in a Michigan
	Trout stream Part I. In-stream sediment basins: A technique for
	removing sand bedload from streams. MDNR Fisheries Research
	Report no.1901.

Merritt, R and Cummins, K. 1984 . An Introduchon to the Aquatic Insects of
	North America. Kendall/Hunt Publishing. Co. Dubuque, IA. 772 pp.