Date of Award

6-2009

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Eric Snyder, Ph.D.

Abstract

Sedimentation affects both stream physical and biological integrity. Improperly designed stream passage accompanied with sedimentation and altered hydrology can impede fish passage and reduce fish assemblage integrity. The purpose of this study was to: 1) quantify impacts of poorly constructed road stream crossings and eroding banks on fish assemblages, and 2) assess these sites as sediment sources and connectivity breaks on entire fish assemblages and individual fish species. Electrofishing was conducted during spring and fall 2004 and 2005. A total of 29 electrofishing reaches were sampled which included 5 road-stream and streambank restoration sites. Sickle Creek (1st order) had reduced diversity and increased dominance above a substantially perched culvert (Shannon’s diversity = 0.180 vs. 0.552; Simpson’s dominance = 0.688 and 0.412 above vs. below, respectively). Pine Creek (2nd order) had 12 reaches sampled, while Bear Creek (4th order) had 7 reaches sampled. In both river systems, fish assemblage response above and below impact sites was mixed, and largely determined by either an up vs. downstream impact. For example, undersized road-stream culverts reduced upstream habitat quality while eroding banks reduced downstream habitat quality. Improvements to road-stream crossings should be done to maximize natural river structure and function.