MONITORING CHANGES IN TRACE ELEMENT CONCENTRATIONS IN AMBLEMA PLICATA IN THE GUADALUPE RIVER BASIN (TEXAS, USA) USING A CAGED TRANSPLANT EXPERIMENT by Joseph William Bakker, B.S. A thesis submitted to the Graduate Council of Texas State University in partial fulfillment of the requirements for the degree of Masters of Science with a Major in Aquatic Resources August 2021 Committee Members: Jessica Dutton, Chair Astrid Schwalb Clint Robertson COPYRIGHT by Joseph William Bakker 2021 FAIR USE AND AUTHOR’S PERMISSION STATEMENT Fair Use This work is protected by the Copyright Laws of the United States (Public Law 94-553, section 107). Consistent with fair use as defined in the Copyright Laws, brief quotations from this material are allowed with proper acknowledgement. Use of this material for financial gain without the author’s express written permission is not allowed. Duplication Permission As the copyright holder of this work I, Joseph W. Bakker, authorize duplication of this work, in whole or in part, for educational or scholarly purposes only. ACKNOWLEDGEMENTS I would like to thank the Texas Parks and Wildlife Department (TPWD) and the United States Fish and Wildlife Service (USFWS) for funding this project. I extend my greatest appreciation to my advisor, Dr. Jessica Dutton, for her guidance, thoughtful feedback, and patience. Without her devotion to aquatic toxicology, this project would not have been possible. Additionally, I would like to thank my committee: Dr. Astrid Schwalb for her valuable advice and knowledge in mussel ecology and Clint Robertson for his important expertise in mussel ecology, and for providing transportation and assistance during the long hours of field work collecting and transferring mussels. Special thanks to Dr. Weston Nowlin for the use of his laboratory and Ashley Cottrell for her assistance in water quality analysis. Also, Dr. Brian Jackson for performing the ICP-MS analysis and Dr. Steven Wiseman for completing the biomarker analysis. I would like to recognize Jacob Ketchum, Kyle Krebs, Meaghan McCormack, Michaela Livingston, Stacey Britton, and Mae Hinson for assistance in the field and the laboratory. I am extremely grateful to my family for their support. Most of all, to my incredible wife Sarah for her love, patience, and partnership throughout this entire process. Thank you all. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ............................................................................................... iv LIST OF TABLES ............................................................................................................. vi LIST OF FIGURES .......................................................................................................... vii ABSTRACT ..................................................................................................................... viii CHAPTER I. INTRODUCTION ................................................................................................1 II. METHODS........................................................................................................13 III. RESULTS ........................................................................................................22 IV. DISCUSSION ..................................................................................................30 LITERATURE CITED .....................................................................................................72 v LIST OF TABLES Table Page 1. Population estimates of Texas cities located on the San Marcos River and Guadalupe River..............................................................................................45 2. GPS coordinates of all study sites .................................................................................46 3. Environmental parameters reported for each time point at each site ............................47 4. Biological measurements of Amblema plicata collected at each site and time point ...48 5. Concentration of essential trace elements in gill tissue of Amblema plicata at each site and time point ......................................................................................49 6. Concentration of non-essential trace elements in gill tissue of Amblema plicata at each site and time point..........................................................................................50 7. Se:Hg molar ratios in gill tissue of Amblema plicata at each site and time point ........51 8. Organic carbon content and grain size distribution as determined by percentage of coarse sediment at each site at week 12 .....................................52 9. Trae element concentrations in sediment collected from each site at week 12 ...........53 10. Essential trace element biota sediment accumulation factors in gill tissue of Amblema plicata at each site and time points ...............................54 11. Non-essential trace element biota sediment accumulation factors in gill tissue of Amblema plicata at each site and time points ...............................55 12. Concentration of nutrients, dissolved organic carbon chlorophyll a, total suspended solids, and non-volatile suspended solids in water collected at each site and time point ........................................................56 13. Concentration of anions and cations in water collected at each site and time point ...............................................................................................................57 14. Spearman’s rank order correlation results between general health indicators and trace elements.........................................................................................................58 vi LIST OF FIGURES Figure Page 1. Location of permitted wastewater outfalls within the Guadalupe River basin .............59 2. Location of study sites within the Guadalupe River basin ...........................................60 3. Concentration of essential trace elements in gill tissue of Amblema plicata at each site at week 0, 3 and 12 of the caged transplant experiment .....................61 4. Concentration of non-essential trace elements in gill tissue of Amblema plicata at each site at week 0, 3 and 12 of the caged transplant experiment .....................62 5. Redundancy analysis biplots of trace element concentrations in gill tissue of Amblema plicata at all sites at week 3.....................................................63 6. Redundancy analysis biplots of trace element concentrations in gill tissue of Amblema plicata at all sites at week 12...................................................64 7. Se:Hg molar ratios in gill tissue of Amblema plicata at each site at week 0, 3 and 12 of the caged transplant experiment .........................................................65 8. Relationship between Se:Hg molar ratios and shell length and Se:Hg molar ratios and Hg concentration in gill tissue of Amblema plicata at all sites and time points .......................................................................................................66 9. Essential trace element biota sediment accumulation factors in gill tissue at each site at week 0, 3 and 12 of the caged transplant experiment ..................................67 10. Non-essential trace element biota sediment accumulation factors in gill tissue at each site at week 0, 3 and 12 of the caged transplant experiment .........................68 11. Nutrient concentrations in water collected at each site at week 0, 3, and 12 of the caged transplant experiment ..................................................................................69 12. Condition factor and total protein in gill tissue at each site at week 0, 3 and 12 of the caged transplant experiment .......................................................................70 13. Hydrographs showing river discharge at each site throughout the 12-week caged transplant experiment .............................................................................................71 vii ABSTRACT Exposure to contaminants, including trace elements, can be one of the reasons for unionid mussel population declines throughout North America. Texas has over 50 species of native mussels, including 16 species that are state threatened; however, little is known about the impact of contaminants on Texas mussels. This study investigated the accumulation of seven essential (Co, Cu, Fe, Mn, Ni, and Zn) and eight non-essential (Ag, As, Bi, Cd, Cr, Hg, Pb, and U) trace elements in gill tissue of Threeridge (Amblema plicata) at six sites in the Guadalupe River Basin, Texas, using a caged transplant experiment. Mussels were collected from a reference site (Lake Wood) and transplanted to five different sites. After 3 and 12 weeks, mussels were collected and the concentration of trace elements in gill tissue was determined using microwave acid digestion and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis. The concentration of trace elements in gill tissue and calculated Biota Sediment Accumulation Factors (BSAF) were compared within and among sites and between week 0, 3 and 12. Overall, mean gill tissue concentrations for essential trace elements were greater than non-essential trace elements. For all sites and time points combined, mean gill concentrations (µg/g dry weight) were greatest for Mn (4641), Fe (838), Zn (433), and As (8.81), and lowest for Cd (0.248), U (0.107), Hg (0.075), and Ag (0.051). Bismuth (Bi) was the only element that was below the detection limit (0.0280 μg/g)