Graduate Thesis Or Dissertation
 

Diving into Diversity: Fish Populations and Climate Resilience in an Endorheic Basin

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0g354p69q

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  • The Goose Lake Basin, situated on the border of Oregon and California, USA, faces significant challenges from drought, wildfire, and other environmental stressors. This region hosts numerous endemic fish species such as the Goose Lake redband trout (Oncorhynchus mykiss newberri), Goose Lake lamprey (Entosphenus sp.), Goose Lake tui chub (Siphateles bicolor), and Goose Lake sucker (Catostomus occidentalis lacusanserinus) alongside many other native and non-native species. Prior to 2022, consistent monitoring had not been conducted in the Basin for over a decade despite this system’s sensitivity to disturbance events and its status as priority habitat for native fish. I sampled a subset of 36 sites previously surveyed by Oregon Department of Fish and Wildlife in 2007, employing electrofishing, habitat sampling, and continuous water temperature data loggers to describe the current fish community structure and identify influential environmental factors. While previous research has been conducted on the effects of climate-mediated disturbances, such as drought, rising water temperatures, invasive species, and wildfire, there remains a significant knowledge gap in understanding how these events affect native fish in the Goose Lake Basin and other arid lands aquatic ecosystems. A key objective of this thesis is to assess how disturbance events post-2007 have impacted the distribution, relative abundance, and habitat utilization of native and non-native fish species in the Basin. In Chapter 1, I provide a comprehensive literature review consolidating prior research on disturbance effects in arid lands ecosystems and historical data collection within the Goose Lake Basin. In Chapter 2, I quantify changes in the fish community since 2007 and identify environmental factors shaping fish community structure. In Chapter 3, I evaluate wildfire impacts on habitat quality, thermal regimes, and observed abundances of redband trout and other coldwater native fishes. For Chapter 2, I used multivariate analyses, including non-metric multidimensional scaling, permutational multivariate analysis of variance, and canonical correspondence analysis, to discern differences in native and non-native fish communities between 2007 and 2022. My results revealed that spatial, rather than temporal, factors were the strongest determinants of fish assemblages in the Basin. Redband trout were highly abundant on the Basin’s east side in the Warner mountains, while native minnows favored lower elevation sites, which were often influenced by agricultural land uses. Although fish community structure remained relatively stable between 2007 and 2022, many species’ abundances fluctuated considerably. In Chapter 3, I used a Before-After-Control-Impact (BACI) study to assess post-fire habitat changes, thermal regimes, and redband trout densities across burned and unburned reaches. Analysis of 2022 and 2006 NAIP imagery facilitated the classification of burn extent and intensity, revealing changes in vegetation and canopy cover. Despite fluctuations, water temperatures generally remained within optimal ranges for redband trout, although stream dewatering issues were frequently observed. While the BACI analysis revealed no significant difference in redband trout density between burned and unburned reaches, it emphasized the multifaceted nature of factors impacting native fish populations post-wildfire. Characterized by its high desert environment and critical wetlands, the Goose Lake Basin is highly susceptible to climate-induced disturbance. My findings will inform future conservation and restoration decisions in this and other arid lands aquatic ecosystems, particularly with respect to climate impacts.
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Related Items
  • Davis Species and Habitat Lab
Hydrologic Unit Code
  • HUC 18020001
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  • Funding for this work was provided by the Oregon Department of Fish and Wildlife, US Fish and Wildlife Service, and the Oregon Watershed Enhancement Board.
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  • 109 pages

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