Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2016 Feeding Ecology of Red Snapper and Greater Amberjack at Standing Platforms in the Northern Gulf of Mexico: Disentangling the Effects of Artificial Light Kristin Leanne Foss Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Oceanography and Atmospheric Sciences and Meteorology Commons Recommended Citation Foss, Kristin Leanne, "Feeding Ecology of Red Snapper and Greater Amberjack at Standing Platforms in the Northern Gulf of Mexico: Disentangling the Effects of Artificial Light" (2016). LSU Master's Theses. 2997. https://digitalcommons.lsu.edu/gradschool_theses/2997 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. FEEDING ECOLOGY OF RED SNAPPER AND GREATER AMBERJACK AT STANDING PLATFORMS IN THE NORTHERN GULF OF MEXICO: DISENTANGLING THE EFFECTS OF ARTIFICIAL LIGHT A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science in The Department of Oceanography and Coastal Science by Kristin Leanne Foss B.S., Millsaps College, 2011 August 2016 To my parents, thank you for your unyielding support, love and guidance. I would not be where I am today without you along every step of the way. ii ACKNOWLEDGEMENTS First of all, I want to thank my advisor, Dr. Jim Cowan, for his words of wisdom, support, and the opportunity to act as project chief scientist and conduct offshore research for my Master’s degree. From day one I have been challenged and pushed to my limits, but I am grateful for the opportunities and experiences I have gained in the Cowan laboratory. Next, I offer a sincere thank you to David Nieland for his patience, mentorship, and kindness he has extended to me these last three years. His experience and tutelage offshore were immeasurable, and I will always be grateful for his assistance to make this project a success. Finally, thank you to Captain Thomas Tunstall and the crew of the BlaZing 7 for making each cruise entertaining, successful, and always getting us back home safely. I want to thank my committee members for their time and support during this graduate process. Thank you to Dr. Michael Polito for introducing me to the world of stable isotope ecology, and for always working patiently with me and putting up with my endless questions as I learned about isotope preparation and modeling. Thank you to Dr. Kevin Xu for being enthusiastic about my fisheries research, and for having an open door to ask questions. Furthermore, I want to thank Dr. Kanchan Maiti, Dr. James Geaghan, Dr. Sibel Bargu-Ates, Dr. Darryl Felder, Dr. Joanne Lyczkowski-Shultz, Shanna Lambert, Lauren Jackson, and Carley Zapfe for their help with my laboratory identification, analyses, and overall moral support. I want to thank all of my lab mates for their emotional and physical support throughout this lengthy graduate endeavor. Thank you to Tori Barker for being a supportive project partner and office mate. Thank you to Hilary Glenn, Dr. Todd Langland, and Brittany SchwartZkopf for their advice, encouragement, and for putting up with my iii endless questioning about writing and analyses all the way from the West Coast. Emily Reynolds, thank you for your ceaseless encouragement, daily support, and especially for your friendship these last three years. Thank you to Jackie McCool, Ashley Melancon Baer, and Courtney Elliton (our honorary lab member) for their friendship, ability to keep me sane, and always being up for a wine night out! A big thank you to Sarah Margolis, LiZZ Keller, Kat Ellis, Alayna Petre, Mario SouZa, and Haixue Shen for all their assistance, hard work, and for making offshore cruises enjoyable. Finally, I would like to thank all of my family and friends for their endless support and encouragement these past three years. Thank you to the Shreveport crew, Millsaps gang, NMFS lab-mates, and of course, my Baton Rouge family (that’s you, book club!) for enduring my thesis-based rants and for their undying support. Thank you to my baby sister, Madison, for putting up sharing an apartment with me. I will always cherish our years in Baton Rouge together. Thank you to my family for encouraging me to dream big and for your undying love and support. Finally, thank you to my faithful, furry friend, Holly, for the endless love even when I was too busy for a walk at the dog park. Thank you to everyone for continuously believing in me. The Louisiana Department of Wildlife and Fisheries funded this project, and the oil platforms were owned and operated by Apache Shelf, Inc., Fieldwood Energy LLC, and Arena Offshore, LP. This project could not have been completed without their support and access. iv TABLE OF CONTENTS ACKNOWLEDGEMENTS ....................................................................................................................................... iii LIST OF TABLES ..................................................................................................................................................... vii LIST OF FIGURES ..................................................................................................................................................... ix ABSTRACT ............................................................................................................................................................... xiii CHAPTER 1: GENERAL INTRODUCTION ........................................................................................................ 1 Literature Cited ..................................................................................................................................................... 8 CHAPTER 2: SEASON- AND SIZE- SPECIFIC DIETS OF RED SNAPPER BETWEEN LIT AND UNLIT STANDING PLATFORMS IN THE NORTHERN GULF OF MEXICO ....................................... 12 Introduction ........................................................................................................................................................ 12 Methods ................................................................................................................................................................. 17 Study Area ....................................................................................................................................................... 17 Sampling Method ......................................................................................................................................... 18 Diet Composition .......................................................................................................................................... 21 Data Analysis .................................................................................................................................................. 22 Results ................................................................................................................................................................... 25 DNA Barcoding .............................................................................................................................................. 27 Nine Prey Category Analysis ................................................................................................................... 30 Comprehensive Prey Item Analysis ..................................................................................................... 36 Discussion ............................................................................................................................................................ 40 Literature Cited .................................................................................................................................................. 46 CHAPTER 3: TROPHIC ECOLOGY OF RED SNAPPER BETWEEN LIT AND UNLIT STANDING PLATFORMS IN THE NORTHERN GULF OF MEXICO ...................................................... 51 Introduction ........................................................................................................................................................ 51 Methods ................................................................................................................................................................. 56 Study Area ....................................................................................................................................................... 56 Stable Isotope Preparation ...................................................................................................................... 57 Data Analysis .................................................................................................................................................. 58 Results ................................................................................................................................................................... 61 MANCOVA ....................................................................................................................................................... 63 SIBER