Dissertation
QUANTITATIVE FOOD WEBS TO DETANGEL CO-LIMITATION AND GUIDE RESTORATION IN NATAL SALMON STREAMS
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000003109
Handle:
https://hdl.handle.net/2376/123059
Abstract
The precipitous decline of anadromous salmonids across the Pacific Northwest is a consequence of anthropogenic changes to freshwater and marine environments. Massive efforts in recent decades to restore natal streams in the Columbia River Basin have taken place with the hope of correcting some of the anthropogenic degradations affecting freshwater life stages. The effectiveness of these restoration actions, however, remains equivocal and represents a fundamental gap in our knowledge and decision making. Recently critiques of effectiveness monitoring have argued for developing a food web approach. In this dissertation I use a trophic basis of production methodology to construct quantitative flow food webs to understand the effect of stream restoration on rearing salmonids. This ecosystem approach uses annual mass/balance calculations to construct energy flow, as well as estimates of food based carrying capacity for fish species. My dissertation consists of four chapters on the development and application of quantitative food webs based on a restoration of a spring ecosystem in north central Washington State (USA). Overall, my dissertation results provide strong evidence that restored riverine habitat can support significantly higher levels (266%) of annual fish production compared to un-restored conditions. However, results also show that invasive brook trout gained the most resource benefit, producing more annual accrued biomass than all target species combined. Using an empirical modelling approach, I simulated the potential carrying capacity gains if brook trout were selectively removed, gains ranged between 18-89%, depending on fish species. By developing this approach, researchers can now evaluate separate as well as additive effects of multiple restoration actions. The method produces both a diagnostic and effectiveness metric, allowing restoration practitioners the ability to chronologically prescribe multiple treatments based on priority limiting factors. Broad application of this quantitative food web approach would significantly improve our understanding of the ecological benefits of contrasting restoration actions aimed at improving freshwater ecosystems and the production of native fishes.
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Details
- Title
- QUANTITATIVE FOOD WEBS TO DETANGEL CO-LIMITATION AND GUIDE RESTORATION IN NATAL SALMON STREAMS
- Creators
- John Jorgensen
- Contributors
- Alex Fremier (Advisor)Barry Moore (Committee Member)Marc Evans (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 99
- Identifiers
- 99900651793701842
- Language
- English
- Resource Type
- Dissertation