Graduation Year

2016

Graduation Month

May

Document Type

Thesis - Campus Access Only

Degree Name

Bachelor of Science

School or Department

Forestry and Conservation, College of

Major

Wildlife Biology – Aquatic

Faculty Mentor

Lisa Eby

Faculty Mentor Department

Wildlife Biology

Faculty Reader(s)

Doug Emlen, Winsor Lowe, Lisa Eby

Keywords

stream ecosystems, long-term impacts, fire, aquatic invertebrate community, cutthroat trout, drift

Subject Categories

Terrestrial and Aquatic Ecology

Abstract

Wildfire frequency and severity in the western U.S. have increased in recent decades and is predicted to continue to increase with climate change. Wildfire can alter stream characteristics resulting in warmer water temperatures, higher sediment and nutrient loading, as well as shifts in aquatic benthic community composition. Few studies have examined decadal impacts of wildfires on stream food webs. Based on habitat changes and previous studies, we predicted that there would be an increase in terrestrial subsidies and shift to more disturbance-adapted aquatic species in burned streams, resulting in burned stream having a higher prey availability and likely energy availability for fish 15 years after wildfire. In August of 2014 and 2015, we examined quantity and quality of Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi, hereafter cutthroat) diets and invertebrate drift in seven unburned streams and seven streams that experienced severe riparian burns in 2000 in the Bitterroot River basin, MT. There was no difference in the proportion of terrestrial invertebrates between treatments in the drift or in cutthroat diets (p=0.47). There was a compositional shift in the aquatic invertebrate community in the drift at the family level to smaller species typically with higher dispersal and turnover rates in streams. This shift was mirrored in cutthroat diets. Total energy availability in the drift was higher in burned streams (p=0.03) than in unburned streams. The differences in drift and trout diets between treatments indicate decadal changes in food web structure that may increase production potential for local fish populations.

Honors College Research Project

Yes

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© Copyright 2016 Rennie A. Winkelman