ECOLOGICAL PROCESS IN PATTERN GENERATION IN TROPICAL CORAL- SEAGRASS REEFSCAPES BY STEPHANIE M. BILODEAU A Thesis Submitted to the Graduate Faculty of WAKE FOREST UNIVERSITY GRADUATE SCHOOL OF ARTS AND SCIENCES in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Biology May 2019 Winston-Salem, North Carolina Approved By: Miles Silman, PhD, Advisor Michael Anderson, PhD, Chair Gregory Asner, PhD ii DEDICATION For my family, especially my parents Susan Rueter and Bill Bilodeau, who have always supported my love of exploration and my journey toward marine science. And for Cliff Lerner, the man who first introduced me to the Belize Barrier Reef. Thank you for starting me on this adventure. iii ACKNOWLEDGEMENTS First, I want to thank my advisor, Dr. Miles Silman, without whom this entire thesis and the projects contained therein would never have happened, for his enthusiasm and support. I would also like to thank my committee members Dr. Michael Anderson and Dr. Greg Asner for their time and valuable insight into my research. I want to thank all the members of the Silman lab and my fellow graduate students who supported me throughout my degree, especially John Gorelick, my partner in crime and co-founder of the Silman lab Surf division. Special thanks to Austin Schwartz, my undergraduate field assistant and fellow researcher in Belize, and to Connor Walsh, our Divemaster and “undergraduate help” for the summer. Thanks to Tati Stroud, who led my team of undergraduates at Wake Forest in classifying thousands of images from the field, and to the entire BIO 312 course for spring 2019. I also want to thank Dr. Paúl Pauca’s machine learning and computer vision team, especially Joseph Chen and Bill Xu, for their help with processing, sorting, and classifying my images. Finally, I want to acknowledge the help and support of Elvis Solis and Julie Robinson in Belize, as well as Dr. Elma Kay at the University of Belize; the Belize Audubon staff and Coast Guard members who welcomed me to Half Moon Caye in 2018; Eli Romero, Dominique Lizama, and Shane Young with the Belize Audubon Society; and Mr. Mauro Gongora and the Belize Fisheries Department who allowed us to conduct research at Lighthouse Reef under Marine Scientific Research Permit number 00021-18. iv Thank you also to Wake Forest Biology, specifically the Vecellio committee, for seeing the value in my research, and to the Wake Forest URECA Center for sponsoring my fantastic undergraduate field assistant, Austin. v TABLE OF CONTENTS List of Figures and Tables ............................................................................................. vii List of Abbreviations ....................................................................................................... ix Abstract ..............................................................................................................................x Introduction: ................................................................................................................... xi Chapter 1: A Global pattern represents the complex interactions driving small-scale benthic changes .................................................................................................................1 Overview ..........................................................................................................................1 The Ecological Role of Pattern and Process ...................................................................2 Coral-Seagrass Ecosystems .............................................................................................3 Halos as a Representative Benthic Pattern ......................................................................4 Current Explanations for Halo Formation .......................................................................7 An Integrated Model of Halo Formation and Maintenance ..........................................14 Implications and Future Directions ...............................................................................16 References .....................................................................................................................18 Chapter 1 Figures and Tables ........................................................................................24 Chapter 2: The role of grazing and fish communities in tropical reefscape benthic patterning..........................................................................................................................26 Introduction ....................................................................................................................26 Methods .........................................................................................................................29 Results ...........................................................................................................................39 Discussion .....................................................................................................................42 References .....................................................................................................................54 Chapter 2 Figures and Tables ........................................................................................63 Chapter 3: A low-cost, long-term underwater camera trap: Methodology and a case study .................................................................................................................................76 Introduction ...................................................................................................................76 Methods .........................................................................................................................79 Results ...........................................................................................................................83 Discussion .....................................................................................................................86 References .....................................................................................................................91 vi Chapter 3 Figures and Tables ........................................................................................96 Appendix ........................................................................................................................102 Curriculum Vitae ..........................................................................................................110 vii LIST OF FIGURES AND TABLES Chapter 1 Figures ............................................................................................................24 Figure 1. Hypothesized interaction between gradients of decreasing nutrients and grazing with distance from the reef ...............................................................................24 Chapter 2 Figures ............................................................................................................63 Figure 1. Seagrass grazing assay locations, 15 inside and 15 outside of the Half Moon Caye MPA ......................................................................................................................63 Figure 2. Grazing assay set-up ......................................................................................64 Figure 3. Seagrass survival within the first 24 hours across three treatments at 30 different sites inside and outside of the Half Moon Caye MPA ...................................65 Figure 4. Vegetation percent cover for 20 camera and diver observation sites across LHR ................................................................................................................................66 Figure 5. Vegetation percent cover for 30 transplant sites, 15 inside and 15 outside of the Half Moon Caye MPA .............................................................................................67 Figure 6. Grazing by surgeonfish and parrotfish of seagrass placed within a halo in the Half Moon Caye MPA, and corresponding lack of grazing in the surrounding seagrass meadow ..........................................................................................................................68 Figure 7. Comparison of biofouling and algal overgrowth of structures placed at the edge of the halo and in the surrounding seagrass ..........................................................69 Figure 8. Non-metric multidimensional scaling based on fish species observations at 20 camera locations, 10 inside and 10 outside of the Half Moon Caye MPA ..............70 Figure 9. Proportion of images containing fish inside and outside of the MPA ...........71 Figure 10. Non-metric multidimensional scaling based on fish species observations at 20 camera locations, 10 at patch reef halos and 10 in nearby seagrass or algae beds ...72 Table 1. GLMM output, showing relative significance of all fixed effects in the model ..............................................................................................................................73 Table 2. Summary of fixed effects in the full factorial linear mixed model ..................74 Table 3. Summary of random effect variances for the full factorial linear mixed model ..............................................................................................................................75 Chapter 3 Figures ............................................................................................................96