Broadly, I’m interested in how human actions affect populations of freshwater fish and insects. My previous and current research projects fall under these areas:

Artificial light and stream functioning
Experimental lights added to a stream in Malcolm Knapp Research Forest.
Photo Credit: Nora Schlenker.

Artificial lights, such as streetlights, are ubiquitous in urban areas. However, the potential effects of artificial lights on the ecology of stream systems is just starting to be researched in earnest. Previously, I found that aquatic invertebrate drift is greatly reduced by light levels typical of urban areas. However, some researchers in Europe did not find a strong response by drifting invertebrates to the experimental addition of light to streams. Undergraduate researchers I have mentored, including an interdisciplinary research team and a thesis student, have found evidence suggesting that aquatic insects exposed to light for many generations may adapt to this disturbance.

Urban Phenology and Interspecific Interactions

Artificial light at night is just one of many stressors faced by stream organisms in urban areas. I am currently developing projects with collaborators that will tease apart how light interacts with changes to temperature and flow to alter the phenology and evolution of stream organisms. I would also like to understand how changes to all three of these cues might interact, or indeed may counteract one another, to change or maintain an organism’s phenology.

In addition to altering phenology, changes in temperature, light, and flow can also change interactions between species. It is possible that normally diurnal visual predators may have their niche expanded by the introduction of artificial light into their habitat. Increases to stream temperatures might give an advantage to one competing species, while a flashier flow regime may tip the balance in favor of another. Better understanding how anthropogenic changes to temperature, light, and flow interact will allow us to understand controls on biodiversity and ecosystem functioning in urban systems as well as potentially improving management of urban waterways.

Differential Response to Environmental Change in Hatchery and Wild Trout

Natural selection and a high level of philopatry has driven wild salmonids to be strongly adapted to the local conditions in their natal watersheds. On the other hand, recent research on hatchery salmonids has shown that they show signs of domestication and reduced fitness relative to their wild counterparts even after just one generation (Blouin et al. 2021). Given that climate change is exerting a rapid and strong selective pressure on wild salmonids, while hatchery trout are raised in the same homogenous environments they always have been, I am interested in understanding how wild and hatchery trout respond to variation in water temperature. Some of the questions I would like to investigate are: Do hatchery and wild trout use the same thermal habitats at the same times? Are there differences in the fitness of hatchery and wild trout under different environmental conditions? How common is hatchery genetic introgression in wild stocks and under what circumstances is introgression particularly high (or low)? Answering these questions would help fisheries managers and would also provide insight into how domestication alters an organism’s ability to deal with environmental change.

Abiotic and Biotic Controls of Urban Fish Populations
Looking upriver at the Kellogg Creek Dam in Milwaukie, OR. This dam has inadequate fish passage preventing fish from accessing important urban habitat.

Urbanization can potentially alter habitat quality and connectivity, resource availability, and lead to changes in interspecific interactions. It is unclear which of these changes exerts the greatest controls over urban fish populations, or if limits to fish population sizes are watershed-specific rather than generalizable. For example, do cutthroat trout population sizes exhibit differing degrees of interannual variation across Portland area urban creeks? Does the cutthroat population in Tryon Creek, that has more development in its headwaters and less along its mainstem, differ from other Portland area cutthroat populations? How do temperature and flow regimes vary across Portland’s urban creeks?