Grand River Watershed Research
Our research in the Grand River watershed focuses on understanding how wastewater treatment plant effluent and other environmental stressors impact fish and aquatic ecosystems.
By integrating field studies, laboratory experiments, and advanced chemical analyses, we examine how complex mixtures of contaminants affect water quality, fish health, and ecological processes. This work links sources of contamination to biological responses, providing a comprehensive understanding of how human activities shape freshwater environments.
Our research spans multiple levels of biological organization, from molecular and physiological responses to whole-organism performance and population-level effects. By combining observations from the field with controlled experimental studies, we are able to identify cause-and-effect relationships and better understand how contaminants influence aquatic systems under real-world conditions.
Fish and Biological Responses
A central focus of our research is the rainbow darter, a widely distributed species in the Grand River that serves as a sensitive indicator of environmental change. While much of this work focuses on rainbow darter, we also study other species such as greenside darter, fantail darter, and blackside darter to better understand species-specific responses to environmental stressors.
Using electrofishing surveys and targeted field sampling, we assess fish populations upstream and downstream of wastewater treatment plant outfalls. Our studies show that wastewater exposure can alter gene expression, physiology, energy allocation, and reproductive performance, ultimately affecting fish populations and communities.
Fish living downstream of wastewater treatment plants can be affected by exposure to effluent. Prior to treatment upgrades, we observed intersex in the rainbow darter, where male fish developed female egg cells in their testes. Following upgrades, the occurrence of intersex declined to levels similar to upstream reference sites, indicating a significant improvement in conditions downstream of treatment plants.
Fathead minnow
Rainbow darter
Early Life Stage Exposure Studies
Understanding how contaminants affect early life stages is a key component of our research. We conduct controlled exposure studies using fathead minnow and local darter species (e.g., rainbow darter, fantail darter) to evaluate how river water, wastewater effluent, and specific chemicals influence reproduction, survival, growth, and behaviour.
By focusing on embryos and larvae, we assess these sensitive developmental stages under environmentally relevant conditions. Endpoints include hatching success, time to hatch, early survival, growth, and behavioural responses, which provide insight into how contaminants affect development and performance during critical life stages. Even subtle changes at these stages can influence feeding, predator avoidance, and overall fitness later in life.
These exposures allow us to compare responses across different water types (e.g., upstream reference sites, wastewater effluent, and downstream locations) and to isolate the effects of specific chemicals or mixtures under controlled conditions. This approach helps identify which contaminants or combinations of contaminants are most likely to impact fish during early development, particularly when organisms are most vulnerable to environmental stressors.
In addition to measuring standard developmental endpoints, we incorporate behavioural and performance-based metrics to capture more subtle effects that may not be immediately apparent but can have important ecological consequences. By linking early-life responses to later biological outcomes, this work provides a critical connection between short-term exposure and longer-term ecological effects, improving our ability to predict how contaminant mixtures influence fish populations in natural systems.
Bioaccumulation and Toxicokinetics
In addition to early life stage studies, we investigate how psychoactive substances accumulate in fish and how this relates to exposure in wastewater-impacted environments. While many pharmaceuticals are water soluble, some compounds such as sertraline are more lipophilic and have a greater potential to bioaccumulate. A range of psychoactive substances, including venlafaxine, diazepam, alprazolam, and tramadol, have been detected in fish tissues, highlighting the need to better understand their uptake and persistence.
To address this, we conduct controlled laboratory exposures at the Water and Environmental Research (WATER) facility using environmentally relevant mixtures of psychoactive substances. These experiments allow us to quantify how chemicals are taken up and eliminated over time and to relate environmental exposure to internal concentrations in fish. This provides key information on how different compounds behave in organisms, including differences in uptake, retention, and elimination.
Understanding these processes is critical because the effects of contaminants are often more closely related to internal concentrations than to those measured in water. By linking environmental exposure to internal dose, our work helps bridge the gap between chemistry and biology. These data are also used to support models that predict how contaminants accumulate in aquatic organisms and how they may influence biological responses under real-world conditions.
Wastewater Treatment and Environmental Inputs
Wastewater treatment plants represent a continuous source of contaminants to the river. Over the past decade, the Region of Waterloo has implemented significant upgrades to its treatment facilities, resulting in measurable improvements in downstream fish and invertebrate communities.
Contaminants released from wastewater occur as complex mixtures from multiple sources, which can be difficult to fully characterize and assess. These upgrades are designed to improve conventional treatment processes, such as the removal of ammonia and nutrients, but they also enhance the removal of some contaminants of emerging concern. Certain pharmaceuticals, such as ibuprofen and naproxen, are relatively well removed during treatment, while more recalcitrant compounds, including carbamazepine and venlafaxine, can persist in treated effluent and the receiving environment.
We combine field observations with controlled laboratory studies at the Water and Environmental Research (WATER) facility to better understand how these contaminants behave and affect aquatic organisms. This integrated approach allows us to identify key drivers of biological responses and supports the development of strategies to reduce impacts on freshwater ecosystems.
Opioids and Emerging Contaminants
The ongoing opioid crisis presents a unique environmental challenge, as the types of compounds entering wastewater systems are continually evolving. While many psychoactive substances are prescribed for therapeutic use, others are used illicitly, making their production, use, and environmental occurrence difficult to track. Substances such as fentanyl, ketamine, MDMA, cocaine, and methamphetamine and their metabolites may be present, but the specific compounds in circulation can change rapidly over time, making them difficult to identify and characterize.
Building on our complementary work in wastewater-based surveillance, we have developed analytical methods for raw wastewater and established collaborative networks to help prioritize rapidly emerging substances of interest. Ongoing efforts focus on expanding the range of detectable compounds, including enantiomers and isomers, and improving approaches to normalize data and interpret trends across systems.
Many psychoactive substances are not fully removed during conventional wastewater treatment and can enter aquatic environments as part of complex mixtures. Our research focuses on identifying and quantifying these compounds in wastewater influent and effluent, as well as in river water and fish downstream of discharge points, to better understand their occurrence and movement in aquatic systems.
