Using hepatic gene expression assays in English sole (Parophrys vetulus) to investigate the effects of Metro Vancouver wastewater effluents in fish

This study investigated the effects of Metro Vancouver's wastewater treatment plant (WWTP) effluents on English sole (Parophrys vetulus) hepatic gene expression using novel targeted gene expression assays to compliment the 2017 Burrard Inlet Ambient Monitoring Program. Seven locations of varying distance to the WWTPs were included. Twelve genes involved in xenobiotic defense (CYP1A, HSP70), thyroid function (DIO1), lipid and glucose metabolism (FABP1, FASN, GLUT2, PPARδ, PPARγ), protein synthesis (18S rRNA, RPS4X), and reproduction (ERα, VTG) revealed several differences between these impacted sites. Strong evidence of exposure to estrogenic contaminants was observed based on male VTG transcript levels with the highest induction nearest Lions Gate primary WWTP, where females exhibited advanced ovarian development. Future studies that incorporate reference sites and controlled lab studies are critical to better understand the natural variation in all measures in this species, and to further develop these potential biomarkers for more thorough risk assessments of WWTP.