Dr. Gerald Tetreault
Research Interests
Gerald completed his MSc in Biology at the University of Waterloo, where he studied the impacts of oil sands development on aquatic ecosystems in the Alberta Athabasca region. His research used reproductive endpoints in small fish species as indicators of environmental exposure and ecosystem health, contributing to early work in Environmental Effects Monitoring (EEM) in industrially influenced watersheds. This work, combined with his experience at Environment and Climate Change Canada, led him to pursue a part-time PhD focused on applying similar effects-based monitoring approaches to municipal wastewater systems.
He completed his PhD in Biology at the University of Waterloo while working at ECCC, co-supervised by Mark Servos and Mark McMaster. Following completion of his PhD, he spent one year as a Postdoctoral Fellow in the Servos Lab before returning to ECCC, where he is currently a Research Scientist.
Gerald is actively involved in the scientific community and has contributed to organizations including the North American Society of Environmental Toxicology and Chemistry (SETAC) and the SETAC Laurentian Chapter, the American Fisheries Society (including the Ontario Chapter), and the Grand River Conservation Authority Fisheries Management Plan Committee (Technical Advisory Sub-group). He has also previously served on the Canadian Water Network Student and Young Professional Committee and the Aquatic Toxicology Workshop Board of Directors.
PhD (Graduated Sep. 2012 )
Gerald’s doctoral research, completed while working at Environment and Climate Change Canada, focused on applying effects-based monitoring approaches to understand the impacts of municipal wastewater effluent on wild fish populations across Canada. Building on Environmental Effects Monitoring (EEM) principles, his work linked contaminant exposure in complex effluents to biological responses in natural receiving environments.
His research examined fish responses across multiple levels of biological organization, ranging from biochemical and physiological endpoints through to reproductive effects and changes in fish community structure. Using sentinel species such as Rainbow Darter and Greenside Darter, he documented altered steroid production, reduced gonadosomatic indices, disrupted gonadal development, and increased incidence of intersex in fish exposed downstream of wastewater treatment plant discharges.
A key component of his PhD involved comparative field studies across multiple Canadian watersheds, demonstrating consistent but site-specific biological effects associated with municipal wastewater effluent exposure. Overall, his work highlighted the importance of integrating mechanistic endpoints with community-level assessments to better understand how wastewater discharges influence aquatic ecosystem health and supported the development of more comprehensive effects-based monitoring frameworks.
Research Associate
Following completion of his PhD, Gerald spent one year as a Research Associate in the Servos Lab, where he continued to investigate the biological effects of municipal wastewater effluent and the responses of fish to wastewater treatment plant (WWTP) upgrades. His work focused on evaluating how improvements in wastewater treatment processes were reflected in measurable changes in fish health and reproductive condition in receiving environments.
During this period, he contributed to field and laboratory studies in the Grand River watershed, including a fish caging experiment in which sentinel fish were deployed upstream and downstream of WWTP discharges to directly assess the effects of effluent under controlled field exposure conditions. This approach improved attribution of observed biological responses to wastewater exposure and supported evaluation of potential recovery following treatment plant upgrades.
He also contributed to research on cumulative effects assessment, integrating multiple lines of evidence to better understand how combined stressors and effluent inputs influence aquatic ecosystem health over time. Through this work, he helped advance effects-based monitoring approaches linking wastewater quality improvements to ecological response and recovery.