FISH ASSEMBLAGES OF CARIBBEAN CORAL REEFS: EFFECTS OF OVERFISHING ON CORAL COMMUNITIES UNDER CLIMATE CHANGE Abel Valdivia-Acosta A Dissertation Submitted to the Faculty of University of North Carolina at Chapel Hill In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Biological Sciences in the Department of Biology, College of Art and Sciences. Chapel Hill 2014 Approved by: John Bruno Charles Peterson Allen Hurlbert Julia Baum Craig Layman © 2014 Abel Valdivia-Acosta ALL RIGHTS RESERVED ii ABSTRACT Abel Valdivia-Acosta: Fish assemblages of Caribbean coral reefs: Effects of overfishing on coral communities under climate change (Under the direction of John Bruno) Coral reefs are threatened worldwide due to local stressors such as overfishing, pollution, and diseases outbreaks, as well as global impacts such as ocean warming. The persistence of this ecosystem will depend, in part, on addressing local impacts since humanity is failing to control climate change. However, we need a better understanding of how protection from local stressors decreases the susceptibility of reef corals to the effects of climate change across large-spatial scales. My dissertation research evaluates the effects of overfishing on coral reefs under local and global impacts to determine changes in ecological processes across geographical scales. First, as large predatory reef fishes have drastically declined due to fishing, I reconstructed natural baselines of predatory reef fish biomass in the absence of human activities accounting for environmental variability across Caribbean reefs. I found that baselines were variable and site specific; but that contemporary predatory fish biomass was 80-95% lower than the potential carrying capacity of most reef areas, even within marine reserves. Second, I examined the effect of current native predatory reef fishes on controlling the invasion of Pacific lionfish across the Caribbean. Native predators and lionfish abundance were not related, even when predatory capacity was relatively high within certain marine reserves. Third, as herbivorous fishes may facilitate coral recovery after warming events by controlling competitive macroalgae, I evaluated whether major benthic groups, such as hard corals, crustose coralline algae, and macroalgae, were associated with these fish assemblages across Caribbean and Pacific reefs. Although, iii macroalgae abundance was negatively related to herbivorous fishes across geographical regions, contemporary coral cover showed no association with herbivores abundance after a recent history of thermal stress. Finally, I analyzed the relationship between ~30 years of thermal stress anomalies and coral assemblages in the Caribbean and suggest that recent warming has partially promoted a shift in coral-community composition across the region that compromise reef functionality. My dissertation research highlights the complex interactions among functional groups in coral reefs, local stressors, and environmental variability across geographical scales, and provides novel insights to reevaluate conservation strategies for this ecosystem in a rapidly changing world. iv To my wife and love of my life, I couldn’t have done this without you. Thank you for all your support during this journey. v ACKNOWLEDGEMENTS First, thanks to my advisor, John Bruno, for all the support, mentorship, knowledge, enthusiasm, discussions, travels, and childish passion for Science that has inspired me and pushed me to grow as a young scientist over the years. Second, to my committee members, I have greatly benefited from your help, support, and constructive criticism over the years. Craig Layman, for always being willing and able to help me with logistics in the field, surveys, editing manuscripts, productive discussions, and providing thorough reviews. Pete Peterson, for providing words of wisdom during meetings and enlighten me with alternative approaches to tackle research questions. Julia Baum, for your honest and thorough reviews; you have inspired me to question conventional wisdom on predatory reef fish ecology. Allen Hurlbert, for assisting me with stats and help me to think about the macroecological perspective of my research questions. Funding for this project has come from a variety of sources. I am particularly grateful to the UNC Institute of Studies of Americas (ISA), especially Beatriz Riefkhol Muniz and Shelley Clark for facilitating financial support through ISA travel grants, a Tinker pre-dissertation grant and a Mellon Dissertation Fellowship that allowed me to fund several research trips to Cuba and the Bahamas over the years. Thanks to UNC Graduate School for travel grants and the Henry Van Peter Wilson Memorial Fund for Marine Biology. I am immensely thankful for the generosity of Dr. Edward and Carol Smithwick for endowing my Royster Society of Fellows Dissertation Completion Fellowship. The support of this fellowship enabled me to focus on my vi research and writing during the last year of my PhD. This fellowship has also provided me with professional development skills crucial in my future career. This work would not have been possible without the continued support of the exceptional graduate students and friends in the Bruno Lab that started with me five years ago. In particular, a special thanks to Courtney Cox, Lindsey Car, and Rachel Gittman for sharing unforgettable moments in the lab, in the field, lab retreats, and at conferences, for your team support and friendship during all this time. Thanks also to Serena Hackerott, Katie Dubois, Karl Castillo, Ivana Vu, Emily Darling, and Clare Fieseler for your help during field seasons in the Bahamas, Belize, and Cuba, for making the journey more than fun, and for discussions about my research questions that have promoted continuing collaborations. Over the last five years, my research has taken me to several countries across the Caribbean. Without the help of colleagues from these places I would not have been able to collect data, obtain research permits, or figure out logistics. Thanks to my colleagues from Cuba, Daylin Muñoz, Maickel Armenteros, Fabian Pina, Tamara Figueredo, Javier Rodriguez, Noel Lopez, the crew of the R/V Itajara, and Patricia Gonzalez, for providing logistic support and help me with field surveys. Special thanks to the crew of the Mexico expedition to the Yucatán Peninsula, Joseph Pawlik, Tse Lynn, Micah Martin, Lindsey Denigan, John Hammer, and Jan Vincent for inviting me to a great adventure across the Mesoamerican barrier. Thanks also to the team in Abaco, Bahamas, including Craig Layman’s students, Betsy Stone, Lauren Yeaguer, Sean Giery, Serina Sebillan, and Joey Peters for allow me to share a house, boats, and food with you. The work in Abaco was also supported by Kristin Williams, from Friends of the Environment and David Knowles from the Bahamas National Trust. Special thanks to Nancee Kumpfmiller, Carolina Stahala, and Rikka Puntilla for your help in Abaco. vii Most importantly, this thesis is dedicated to my wife and love of my life, Elizabeth Valdivia. Thank you very much for all the support, help, patience, sacrifices, and unconditional love you have given me over the past years. I couldn’t have done it without you and I am very lucky to share this long journey with you. This degree goes to both. I am also very thankful of my parents, Juana Acosta and Abel Valdivia (father) and my super brother Alain Valdivia for being there all my life, for supporting me in all my decisions, for their love, and for believing in me all the way. I want to express a huge gratitude to my Wisconsin family, Barbara and Tim Poser, Sadie and Justin Poser, and Kristin and Maickel Poser, for their understanding and wonderful times during holiday seasons that took me away every semester during grad school. Finally, thank you to my almost family, Daylin Munoz and Nancee Kumpfmiller for their friendship and love over the years. viii TABLE OF CONTENTS LIST OF TABLES ......................................................................................................................... xi LIST OF FIGURES ...................................................................................................................... xii CHAPTER 1: Reconstructing baselines for Caribbean predatory reef fishes ................................ 1 Abstract ................................................................................................................................1 Introduction ..........................................................................................................................2 Materials and Methods .........................................................................................................6 Results ................................................................................................................................12 Discussion ..........................................................................................................................17 Conclusion and implications ..............................................................................................22 References ..........................................................................................................................30 CHAPTER 2: Re-examining the relationship between invasive lionfish and native grouper in the Caribbean ........................................................................................ 35 Abstract ..............................................................................................................................35