Ashley Mickens

Topic

Characterizing the morphological and elemental traits of threespine stickleback across an urbanization gradient on Vancouver Island

Department of Biology

Date & location

• Wednesday, September 3, 2025
• 1:30 P.M.
• Clearihue Building, Room B021

Examining Committee

Supervisory Committee

• Dr. Rana El-Sabaawi, Department of Biology, University of Victoria (Supervisor)
• Dr. Francis Juanes, Department of Biology, UVic (Member)
• Dr. Nancy Shackelford, School of Environmental Studies, UVic (Outside Member)

External Examiner

• Dr. John Kominoski, Department of Biological Sciences, Florida International University

Chair of Oral Examination

• Dr. Caetano Dorea, Department of Civil Engineering, UVic

Abstract

Urbanization increasingly alters the landscapes surrounding cities. Anthropogenic impacts associated with urbanization, such as increased nutrients, habitat degradation, and the introduction of invasive species significantly impact the health of aquatic ecosystems. While many studies look at the relationship between urbanization and water quality, fewer look at how urbanization alters organismal traits, although there is increasing evidence that they are important for explaining the effect of urbanization on biodiversity. In this study, we examine the effect of urbanization on the traits of a common North American fish species, the Threespine Stickleback (Gasterosteus aculeatus). During summer 2022 and 2023, we collected stickleback from 15 freshwater locations on Vancouver Island across a gradient of urbanization. We quantified urbanization using three metrics constructed from several methods based on human population size density, infrastructure and land use. These metrics were used to analyze seven stickleback traits via principal component analyses (PCAs) and mixed effects linear models with AICc model selection. Our findings showed that urbanization increases body size, but had no relationship with the other six traits. This work provides recommendations on where to focus future sampling and conservation efforts while providing a framework for other researchers to carry out similar studies, thus increasing our understanding of the effects of urbanization on lake ecosystems.