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Factors Affecting Mercury Concentrations in Iowa Fishes Nathan Taylor Mills Iowa State University

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Factors Affecting Mercury Concentrations in Iowa Fishes Nathan Taylor Mills Iowa State University Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2016 Factors affecting mercury concentrations in Iowa fishes Nathan Taylor Mills Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Agriculture Commons, Animal Sciences Commons, Environmental Sciences Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Mills, Nathan Taylor, "Factors affecting mercury concentrations in Iowa fishes" (2016). Graduate Theses and Dissertations. 15976. https://lib.dr.iastate.edu/etd/15976 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Factors affecting mercury concentrations in Iowa fishes by Nathan Taylor Mills A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Fisheries Biology Program of Study Committee: Michael J. Weber, Co-Major Professor Clay L. Pierce, Co-Major Professor Joel R. Coats Iowa State University Ames, Iowa 2016 Copyright © Nathan Taylor Mills, 2016. All rights reserved. ii TABLE OF CONTENTS DEDICATION ............................................................................................................................... iv ACKNOWLEDGEMENTS .............................................................................................................v ABSTRACT ................................................................................................................................... vi CHAPTER 1. GENERAL INTRODUCTION ................................................................................1 References ............................................................................................................................7 CHAPTER 2. SEASONAL VARIATION OF FISH MERCURY CONCENTRATIONS ..........11 Abstract ..............................................................................................................................11 Introduction ........................................................................................................................13 Methods..............................................................................................................................15 Results ................................................................................................................................17 Discussion ..........................................................................................................................19 References ..........................................................................................................................22 Tables and Figures .............................................................................................................25 CHAPTER 3. FACTORS INFLUENCING FISH MERCURY CONCENTRATIONS IN IOWA LAKES ...................................................................................................................29 Abstract ..............................................................................................................................29 Introduction ........................................................................................................................31 Methods..............................................................................................................................33 Results ................................................................................................................................41 Discussion ..........................................................................................................................46 References ..........................................................................................................................50 Tables and Figures .............................................................................................................55 CHAPTER 4. FACTORS INFLUENCING FISH MERCURY CONCENTRATIONS IN IOWA INTERIOR RIVERS ..............................................................................................84 Abstract ..............................................................................................................................84 Introduction ........................................................................................................................86 Methods..............................................................................................................................88 Results ................................................................................................................................95 Discussion ........................................................................................................................100 References ........................................................................................................................104 Tables and Figures ...........................................................................................................108 iii CHAPTER 5. MANAGEMENT IMPLICATIONS ....................................................................132 APPENDIX A. META-ANALYSIS DATA – CHAPTER 2 ......................................................134 APPENDIX B. VARIABLE ABBREVIATIONS – CHAPTER 3 .............................................138 APPENDIX C. CORRELATION TABLE – CHAPTER 3 .........................................................140 APPENDIX D. WATERSHED AND WATER QUALITY DATA – CHAPTER 3 ..................144 APPENDIX E. FISH LENGTH VERSUS MERCURY RELATIONSHIPS – CHAPTER 3 ...146 APPENDIX F. MISSOURI AND MISSISSIPPI RIVER DATA – CHAPTER 3 ......................147 APPENDIX G. VARIABLE ABBREVIATIONS – CHAPTER 4 .............................................148 APPENDIX H. CORRELATION TABLE – CHAPTER 4.........................................................149 APPENDIX I. WATER QUALITY DATA – CHAPTER 4 .......................................................153 APPENDIX J. FISH LENGTH VERSUS MERCURY RELATIONSHIPS – CHAPTER 4 .....154 APPENDIX K. FISH LENGTH IN INCHES VERSUS MERCURY– CHAPTER 3 ................155 APPENDIX L. FISH LENGTH IN INCHES VERSUS MERCURY– CHAPTER 4. ................156 iv DEDICATION I dedicate this thesis to my family, friends, and to the memory of my grandfather, Harvey Mills, for the support they have given me throughout this project. v ACKNOWLEDGEMENTS This project is funded by the Iowa Department of Natural Resources through contract 14CRDFBGSCHO-0002 and Iowa State University as part of an ongoing evaluation of mercury contamination in Iowa fishes. Special thanks to Iowa Department of Natural Resources Fisheries Biologist, Darcy Cashatt, for her advice, patience, and dedication to the success of this project. I would also like to thank other fisheries personnel throughout Iowa that have assisted with fish collection and provided fishes for this project. Finally, I would like to thank Adam Martin- Schwarze with the Statistics Department at Iowa State University for helping with the statistical analyses used in this study. This study was performed under the auspices of Iowa State University Institutional Animal Care and Use Committee (IACUC) protocol permit 4-14-7780-I, and animals were collected under state permit SC1037. Use of trade, product, or firm names is descriptive and does not imply endorsement by the U.S. Government. vi ABSTRACT Mercury contamination in aquatic ecosystems is a global concern due to the health risks of consuming contaminated aquatic organisms, particularly fishes. Mercury concentrations in fishes are highly variable and influenced by a range of biotic and abiotic variables. Currently, factors influencing mercury accumulation in Iowa fishes are not well understood. The Iowa Department of Natural Resources (IDNR) has issued fish consumption advisories for various lakes and river reaches throughout the state. However, relatively few systems, species, and individuals are sampled each year and little is known regarding factors affecting mercury concentrations in Iowa fishes. An understanding of factors regulating mercury concentrations in Iowa fishes would improve mercury monitoring programs and consumption guidelines. The objectives of this study were to (I) evaluate seasonal variation in mercury concentrations in largemouth bass ( Micropterus salmoides ) from two reservoirs to assess the need for temporally standardized mercury sampling and (II) evaluate the influence of a suite of biotic and abiotic factors on fish mercury concentrations in both river and lake systems. Largemouth bass were intensively sampled from Red Haw and Twelve Mile lakes to evaluate temporal variation in largemouth bass mercury concentrations. Bluegill ( Lepomis macrochirus , n = 275), white and black crappie ( Pomoxis annularis , n = 112; P. nigromaculatus , n = 203), largemouth bass (n = 502), walleye ( Sander vitreus , n = 248), muskellunge ( Esox masquinongy , n = 30), and northern pike ( E. lucius , n = 45) were collected between April and October, 2013-2015, from natural lakes (n = 6), shallow natural lakes (n = 2), constructed lakes (n = 18), and reservoirs (n = 4) throughout Iowa. Additionally, channel catfish ( Ictalurus punctatus , n =
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