Investigating Effects of the Piscicide Rotenone on Amphibians in Southwestern Montana Through Laboratory Experiments and Field Trials By Hilary Gray Billman A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Biological Sciences Idaho State University October 2010 1 Acknowledgements Graduate school has provided me with a multitude of experiences and opportunities that will continue to influence both my personal and professional lives, and for this I am forever thankful. I would like to first thank the two people who worked tirelessly to help me turn graduate school into a reality, Charles Peterson and Todd Koel. Their perseverance and unflagging belief in my abilities ensured that my grad school dreams would be realized, and I will always be grateful to them for that. Of course, getting into school was only half the battle and I would like to recognize all the people who helped me through the ensuing journey. Specifically, I would like to thank my committee members – Sophie St-Hilaire, Charles Peterson, Carter Kruse, and Colden Baxter – for all their time, hard work, and guidance throughout the course of my time at ISU. I would like to thank my funding sources, in no particular order of importance, all of which made the completion of this work possible. Idaho State University provided me with TA funding during the 2007-2008 academic year. The National Park Service, specifically the Fisheries and Aquatic Sciences Section, provided me with employment, vehicles, equipment, and staff assistance during the 2006-2008 seasons. Turner Enterprises, Inc. provided me with funding during the 2008-2009 academic year, equipment, laboratory space, staff assistance, and employment. Finally, the Montana Chapter of the American Fisheries Society provided me with funding that was put toward equipment purchases. I would like to extend gratitude to all of the faculty, staff, and students of the Department of Biological Sciences. Specifically, I’d like to thank the members of the Herpetology lab – Sue Parsons, Jason Jones, Javan Bauder, Scott Cambrin, Dave Hilliard, and Chris Jenkins – who provided advice, contributed to discussions, and made things fun. Additionally, I’d like to thank Peter Murphy and Teri Peterson for help with statistical analyses. A number of folks from both Turner Enterprises, Inc and YNP were involved in this project. Their assistance was invaluable. I’d specifically like to thank Jeff Arnold, 1 Lyndsay Belt, Preston Debele, Brian Ertel, Mike Konsmo, Reid Koskiniemi, Kate Olsen, Mike Ruhl, John Sorenson, and John Treanor. I also want to thank my family and friends. Between rock hopping in the creek behind the house looking for crayfish, searching tidal pools in Maine, exploring the national parks, or watching birds at the feeder, my parents introduced me to the natural world at an early age, ensuring that it would become an integral part of my life forever. They instilled in me a strong desire for the continuous pursuit of knowledge, and always reminded me to pursue what I loved. They continue to support my endeavors, and have provided me with guidance and encouragement throughout this process. Most importantly, they have always been interested in my work and research, always wanting updates on what I was up to. Mom and dad, I told you at the age of 10 that I was going to be a herpetologist when I grew up, and here I am! My sister has been a constant friend and advisor, always ready to listen. Though our paths are different, she has shared in my love of the natural world and I so greatly appreciate the unfailing enthusiasm she has shown over the years for my activities. Her kindness, determination, and constant pursuit of helping others inspire me daily. I would also like to thank my friends for supporting me through this long process. I am extremely lucky to be surrounded by such a great group of people, and I could not have completed this without your help, understanding, and occasional refusal to let me work on the weekends. The list is long, too long to mention you all, but you know who you are. Last, but certainly not least, I would like to thank all the tadpoles that submitted to being part of this experiment. While I have always recognized the purpose this research will serve for the greater good of amphibians in fish restoration areas in the years to come, I have been painfully aware of the mortality that was inevitably part of my research. This sacrifice will be for the benefit of many tadpole generations in the future! iii Table of Contents List of Chapter Two Figures………………………………………………………….......vi List of Chapter Two Tables……………………………………………………………...vii List of Chapter Three Figures…………………………………………………………...viii List of Chapter Three Tables……………………………………………………………..ix Summary…………………………………………………………………………………..x Chapter One: Introduction………………………………………………………………...1 Literature Cited……………………………………………………………………8 Chapter Two……………………………………………………………………………...15 Abstract…………………………………………………………………………..15 Introduction………………………………………………………………………16 Methods…………………………………………………………………………..19 Results……………………………………………………………………………23 Discussion………………………………………………………………………..26 Literature Cited…………………………………………………………………..32 Tables & Figures…………………………………………………………………37 Chapter Three……………………………………………………………………….........43 Abstract…………………………………………………………………………..43 iv Introduction………………………………………………………………………44 Study Area……………………………………………………………………….47 Methods…………………………………………………………………………..49 Results……………………………………………………………………………54 Discussion………………………………………………………………………..57 Literature Cited…………………………………………………………………..63 Tables & Figures…………………………………………………………………68 Chapter Four: Conclusions…………………………………………………………........76 Literature Cited…………………………………………………………………..81 v List of Chapter Two Figures Figure 2.1: 2008 cumulative mortality curves for spotted frog tadpoles………………...37 at all three age stages. Figure 2.2: 2009 cumulative mortality curves for boreal toad tadpoles……………........38 at all three age stages. Figure 2.3: Average mortality by age stage of spotted frog tadpoles……………………39 exposed to 1 mg/L CFT Legumine for 96 hours in 2008 and 2009. Figure 2.4: Average mortality by age stage of boreal toad tadpoles…………………….40 exposed to 1 mg/L CFT Legumine for 96 hours in 2009. Figure 2.5: 2009 average mortality by treatment group (i.e. exposure length)………….41 of spotted frog tadpoles over a 96 hour period at 1 mg/L product. vi List of Chapter Two Tables Table 2.1: 2009 percent mortality of spotted frog tadpoles at all three age stages………42 after 4 and 96 hours of exposure to CFT Legumine at 1 mg/L. vii List of Chapter Three Figures Figure 3.1: Location of the High Lake and Flying D ranch study sites in……………….68 Southwestern Montana Figure 3.2: High Lake study sites………………………………………………………..69 Figure 3.3: Tadpole population estimates at High Lake for each of 2006-2009………...70 Figure 3.4: Flying D Ranch tadpole population estimates at control ponds (n = 2)……..71 and treated ponds (1 mg/L; n = 2). viii List of Chapter 3 Tables Table 3.1: Water quality parameters at High Lake and the two associated……………...72 wetlands Table 3.2: Water quality parameters at the wetlands on the Flying D Ranch…………...73 Table 3.3: Tadpole population estimates obtained at High Lake………………………..74 and the 2 control wetlands in each of 2006, 2007, 2008, and 2009 Table 3.4: Tadpole population estimates obtained at control……………………………75 and treated ponds on the Flying D Ranch before (2008) and after (2009) the rotenone treatment (1 mg/L product). ix Summary Over the past two decades, amphibian populations have experienced significant decline world-wide as a result of habitat loss, habitat alteration, disease, and climate change. To better conserve amphibian communities, it is imperative to develop a knowledge base of how amphibians respond to habitat alterations and environmental stressors. Amphibian habitat changes in the western United States are occurring, in part, as a result of native fish restoration practices. To reverse the impacts of introduced, non-native fish species, fisheries managers are removing non-native species and restoring native species to historic habitats. A preferred and efficient method for removal of non-native fish species is through the use of approved piscicides, but these chemicals can have measurable, negative effects on amphibian populations. The focus of this research is to determine the effects of piscicide use on amphibians through controlled laboratory experiments and field investigations in southwestern Montana. Laboratory trials demonstrated that rotenone exposure at 1 mg/L (product) was lethal to tadpoles of two species – Columbia spotted frog Rana luteiventris and boreal toad Anaxyrus boreas – at all three age stages tested. In spotted frog tadpoles, the probability of mortality decreased as age increased, while age did not affect average mortality in boreal toad tadpoles. Tadpole species had a significant effect on mortality only at the oldest age stage, with spotted frog tadpoles experiencing lower mortality then boreal toad tadpoles (p<0.001). Sub-lethal effects on morphology, although statistically different between control and exposed spotted frog survivors in two instances, were not consistent and were not considered biologically significant. My results further indicated that as the duration of rotenone exposure increased, spotted frog tadpole mortality increased, except at the oldest age stage. The results of the field investigations revealed that, in the 24 hours following application, rotenone was lethal to gill-breathing amphibian tadpoles and non-lethal to non-gill breathing metamorphs, juveniles, and adults. In the year(s) following, tadpole repopulation occurred at all water bodies treated with rotenone product. The information obtained from these two components will be used to better inform future fish restoration actions. x