UC Riverside UC Riverside Electronic Theses and Dissertations Title The Effects of Temperature, Salinity, and Bifenthrin on the Behavior and Neuroendocrinology of Juvenile Salmon and Trout Permalink https://escholarship.org/uc/item/9jv04705 Author Giroux, Marissa Sarah Publication Date 2019 License https://creativecommons.org/licenses/by-nd/4.0/ 4.0 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA RIVERSIDE The Effects of Temperature, Salinity, and Bifenthrin on the Behavior and Neuroendocrinology of Juvenile Salmon and Trout A Dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Environmental Toxicology by Marissa S. Giroux June 2019 Dissertation Committee: Dr. Daniel Schlenk, Chairperson Dr. David Volz Dr. Andrew Gray Copyright by Marissa S. Giroux 2019 The Dissertation of Marissa S. Giroux is approved: Committee Chairperson University of California, Riverside ACKNOWLEDGEMENTS Without the support, guidance, training, and time of many people this dissertation would not be possible. First, I would like to thank my Advisor, Dr. Daniel Schlenk for his help in in applying for fellowships, guidance in experimental design, taking the time to help me network, and giving me the opportunity to teach and mentor in both the lab and classroom. I would also like to thank my committee members, Dr. David Volz and Dr. Andrew Gray, for their wonderful recommendations and advice throughout my years at UC-Riverside. I have immense gratitude for my lab family, both past and present, who trained me, supported me, and taught me all of the “other” things you learn in grad school. I am so thankful for everything I learned from Dr. Allison Kupsco, Dr. Graciel Diamante, Dr. Luisa Becker Bertotto, Dr. Scott Coffin, Nikki Andrzejczyk, Tori McGruer, Gary Harraka, Phil Tanabe, Dr. Justin Greer, and Dr. Jason Magnuson. I could not have completed my projects without the assistance of the dedicated undergraduate volunteers Leslie Caceres, Danny Luu, and Norma Mejivar-Cervantes. Financial support for my research, stipend, and conference travel was provided by the Delta Stewardship Council Delta Science Program and the State and Federal Contractors Water Agency (grant number R/SF-79 2271), UCR/AES resource allocation program, Chancellor’s Distinguished Fellowship Program, Environmental Toxicology Fukuto travel fund, and UCR Graduate Student Association travel awards. iv Chapter 4 of this dissertation is a reprint of the material titled “The effects of bifenthrin and temperature on the endocrinology of juvenile Chinook salmon” published in 2019 in Environmental Toxicology and Chemistry, volume 38, issue 4, pages 852-861. The coauthor Dr. Jay Gan provided laboratory space, instrumentation, and expertise for bifenthrin measurements in water sample. Dr. Daniel Schlenk supervised and advised the research projects in this dissertation. v DEDICATIONS I dedicate this dissertation to my mother, my first woman in science role model, who never let me forget my goals and showed me how to be strong. I also dedicate this dissertation to my grandmothers, who demonstrated to me true inner strength. vi ABSTRACT OF THE DISSERTATION The Effects of Temperature, Salinity, and Bifenthrin on the Behavior and Neuroendocrinology of Juvenile Salmon and Trout by Marissa S. Giroux Doctor of Philosophy, Graduate Program in Environmental Toxicology University of California, Riverside, June 2019 Dr. Daniel Schlenk, Chairperson The San Francisco Bay-Delta in California has been experiencing increasing surface water temperatures, salt water intrusion, and intense runoff events that wash pyrethroids into waterways. Salmonid populations in the Bay-Delta have been declining, including the endangered Steelhead trout ( Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha ). Previous studies suggest that estrogenic compounds can inhibit smoltification, and the pyrethroid pesticide bifenthrin has been shown to have estrogenic effects. Thus, the objective of my research was to investigate the effects of bifenthrin and climate change stressors on the neuroendocrine response of juvenile salmonids. Trout alevin and fry were exposed to 11 0C, 16.4 0C and 19 0C temperatures and then immediately challenged to sea water (SW) for 24 hours. Trout parr were slowly acclimated to SW and simultaneously exposed to the same temperature regime. Estradiol- 17β, cortisol, triiodothyronine, and thyroxine hormone levels were measured in blood serum or whole animal homogenates using ELISAs. Brain growth hormone 1, brain gonadotropin-releasing hormone receptor 2, and gill Na+/K+ ATPase mRNA levels were vii measured using qPCR. Alevin were more sensitive to salinity than temperature, and fry were more susceptible to increasing temperatures, thus demonstrating stage-dependent responses to climate change stressors. To evaluate the combined effects of bifenthrin and temperature, Chinook alevin, fry, and parr were exposed to the same temperature stressors for 10 days (alevin) or 14 days (fry and parr) and, in the final 96 hours of rearing, fish were exposed to 0, 0.15, or 1.5µg/L bifenthrin. The same endpoints were measured as in the trout, with the addition of quantifying testosterone levels, the expression of brain dopamine receptor 2α, and measuring brain dopamine levels. In addition, a predator avoidance Y-Maze behavioral assay was conducted on parr. Bifenthrin significantly impacted olfactory-mediated predator avoidance behaviors in parr. These results suggest that temperature may be impacting endocrine pathways differently at each juvenile stage because of the developmental timing of neuroendocrine signaling pathways. Together, these studies provide insight to how multiple stressors and sublethal pesticide exposure may have population-level impacts on Bay-Delta salmonid populations. viii Table of Contents Chapter 1: Introduction Salmonids………………………………………………………………………….1 Decline of California Salmon and Trout…………………………………………..3 Smoltification……………………………………………………………………...5 Climate Change Stressors.………………………………………………………...9 Contaminants in the Bay-Delta.………………………………………………….12 Classes of Pyrethroids……………………………………………………………15 Fate and Transport of Bifenthrin...……………………………………………….15 Adsorption and Exposure of Bifenthrin………………………………………….18 Bifenthrin Biotransformation…………………………………………………….18 Mechanisms of Toxicity of Bifenthrin..………………………...………………..20 Toxicity to Non Target Organisms……………………………………………....23 Endocrine Disruption…………………………………………………………….26 Fish Behavior…………………………………………………………………….28 Combined Contaminant and Climate Change Stressors…………………………30 Research Objectives……………………………………………………………...31 References………………………………………………………………………..33 Chapter 2:The Effects of Temperature and Salinity on the Endocrinology of Smoltification in Juvenile Rainbow/Steelhead Trout ( Oncorhynchus mykiss )...……43 Abstract………………..………………..………………..………………………43 Introduction………………..………………..………………..…………………..44 Methods………………..………………..………………..………………..……..47 Results………………..………………..………………..………………………..52 Discussion………………..………………..………………..……………………61 Conclusions…………..………………..…………………………..……………..65 References…………..………………..…………………………..………………66 Chapter 3: The effects of the climate change stressors temperature and salinity on the endocrinology of endangered juvenile Steelhead trout ( Oncorhynchus mykiss )..69 Abstract………………..………………..………………..………………………69 Introduction………………..………………..………………..…………………..70 Methods………………..………………..………………..………………..……..72 Results………………..………………..………………..………………………..76 Discussion………………..………………..………………..……………………81 Conclusions…………..………………..…………………………..……………..84 References…………..………………..…………………………..………………86 Chapter 4: The Effects of Bifenthrin and Temperature on the Endocrinology of Juvenile Chinook Salmon ................................................................................................89 Abstract………………..………………..………………..………………………89 Introduction………………..………………..………………..…………………..90 ix Methods………………..………………..………………..………………..……..93 Results………………..………………..………………..………………………..99 Discussion………………..………………..………………..……………..……107 Supplemental Data……………………………………………………………...117 References…………..………………..…………………………..…………..…119 Chapter 5: The Effects of Temperature and Bifenthrin on the Endocrinology and Behavior in Parr of Chinook Salmon ( Oncorhynchus tshawytscha )……………….. 123 Abstract………………..………………..………………..……………………..123 Introduction………………..………………..………………..…………………124 Methods………………..………………..………………..……………….…….127 Results………………..………………..………………..…………………..…..133 Discussion………………..………………..………………..…………………..140 Conclusions…………..………………..…………………………..……………144 Supplemental Data……………………………………………………………...145 References…………..………………..…………………………..……………..149 Chapter 6: Conclusion ……..………………..………………………………………...153 References……..………………..……………………………………………....158 x List of Tables Table 1.1 Pyrethroid sources and frequency in the Bay-Delta…………………..............16 Table 3.1 Average percent survival of Steelhead parr exposed to increasing temperature and salinity……………………………………………………………………………….78 Table 4.1 Measured mean concentrations of bifenthrin in fry exposures for 0 and 96 hours……………………………………………………………………………………102 Table 4.2 Primers used for qPCR of alevin and fry brain tissue……………………….118 Table 5.1 Measured mean concentrations of bifenthrin in all temperature exposures at 0, 24, 48, and 96 hours……………………………………………………………………148 xi List of Figures and Diagrams Figure 1.1 Salmonid lifecycle……………………………………………………………2