Portland State University. Department of Environmental Science and Management
Term of Graduation
Date of Publication
Master of Science (M.S.) in Environmental Science and Management
Environmental Science and Management
1 online resource (ix, 88 pages)
Stream restoration is a proposed climate adaptation tool, however, outcomes of floodplain restoration on stream temperature have been debated. Despite a growing number of studies that investigated water temperature in restored streams, few have quantified thermal heterogeneity in new habitat types created by restored hydrogeomorphic processes and the impact of thermal diversity on the aquatic macroinvertebrate community. In this study, I evaluated three hypotheses: 1) restoration increases habitat diversity, 2) habitat diversity increases water temperature heterogeneity, and 3) restored reaches have more diverse macroinvertebrate communities. I collected a total of 40 macroinvertebrate samples and characterized environmental conditions in three reaches (degraded as control, recently restored as transitional, and restored) in a restored steam Whychus Creek, Oregon, USA in summer, 2021. The restored reaches of this study were restored to Stage 0 condition, defined as, "a valley-scale, process-based (hydrologic, geologic and biological) approach that aims to reestablish depositional environments to maximize longitudinal, lateral, and vertical connectivity at base flows, and facilitate development of dynamic, self-forming and self-sustaining wetland-stream complexes" (Flitcroft et al. 2022). Temperature loggers were deployed to collect data at 30-minute intervals over two days at the location of each macroinvertebrate sample. Shannon index scores for habitat diversity were more than two times higher in restored reaches than in the control reach. Water temperature coefficient of variation for three common temperature metrics, the maximum, minimum, and mean temperature, ranged from 5.5%-20.2% in two restored reaches, two times or more variability compared to the control reach. Median taxa richness was 19, 18, and 13 for the restored, control, and transitional reaches, respectively. Off-channel habitats in the restored reaches included 16 taxa not found in other habitat types. Range in weighted mean thermal optima for macroinvertebrates was 1.5-2 times more in restored reaches compared to the control. Results from this study support that restored floodplains and streams in Stage 0 condition have thermal heterogeneity and diverse macroinvertebrate communities.
©2023 Wesley Nathan Noone
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Noone, Wesley Nathan, "Impacts of Floodplain Restoration on Water Temperature and Macroinvertebrates in Whychus Creek, Oregon" (2023). Dissertations and Theses. Paper 6413.