Dr. Keegan Hicks

Keegan worked as a postdoctoral fellow in the Servos Lab following the completion of his PhD, continuing to further explore outstanding questions related to endocrine disruption in aquatic systems. His research focused on estrogenic and endocrine-related responses in rainbow darter (Etheostoma caeruleum), examining how the timing of contaminant exposure influenced the expression of biological responses in wild fish, with particular emphasis on linking exposure windows to variability in physiological and reproductive outcomes. This work built on long-term studies in the Grand River watershed examining the effects of municipal wastewater effluent on fish health and endocrine disruption.

Keegan’s PhD research investigated the response of wild fish populations to municipal wastewater treatment plant (MWWTP) upgrades in the Grand River watershed. His work focused on understanding how changes in effluent quality influenced ecological and biological responses in downstream aquatic systems, using rainbow darter (Etheostoma caeruleum) as a sentinel species.

The research integrated historical and newly collected data to assess responses across multiple levels of biological organization, including nutrient cycling, stable isotope signatures (δ¹⁵N and δ¹³C), fish community composition, and reproductive health endpoints such as intersex. A major focus was evaluating changes following upgrades to the Kitchener MWWTP, which led to improved effluent quality, including reductions in nutrients, pharmaceuticals, and estrogenicity. These improvements were associated with substantial reductions in intersex in male rainbow darter, with rates declining by up to 70% shortly after upgrades and returning near background levels within several years.

The thesis also examined fish movement patterns through a mark-and-recapture study, demonstrating that while most rainbow darter exhibited strong site fidelity, a small proportion moved substantial distances. This finding helped clarify potential confounding factors in interpreting near-field exposure gradients.

Overall, the work demonstrated that conventional wastewater treatment upgrades led to measurable improvements in aquatic ecosystem health and provided important insights into the use of wild fish as sentinels for assessing wastewater impacts and recovery trajectories.

Keegan is currently working with the Government of Alberta as a Fisheries Biologist/Researcher.