University of South Carolina Scholar Commons Theses and Dissertations 5-2017 Causes and Consequences of Individual Phenotypic Differences in Brachyuran Crabs With A Focus on Behavior Benjamin A. Belgrad University of South Carolina Follow this and additional works at: https://scholarcommons.sc.edu/etd Part of the Marine Biology Commons Recommended Citation Belgrad, B. A.(2017). Causes and Consequences of Individual Phenotypic Differences in Brachyuran Crabs With A Focus on Behavior. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/4054 This Open Access Dissertation is brought to you by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. CAUSES AND CONSEQUENCES OF INDIVIDUAL PHENOTYPIC DIFFERENCES IN BRACHYURAN CRABS WITH A FOCUS ON BEHAVIOR By Benjamin A. Belgrad Bachelor of Science Eckerd College, 2013 Submitted in Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy in Marine Science College of Arts and Sciences University of South Carolina 2017 Accepted by: Blaine D. Griffen, Major Professor Ryan R. Rykaczewski, Committee Member James L. Pinckney, Committee Member Amy E. Fowler, Committee Member Cheryl L. Addy, Vice Provost and Dean of the Graduate School © Copyright by Benjamin A. Belgrad, 2017 All Rights Reserved. ii ACKNOWLEDGEMENTS First and foremost, I wish to thank my mother, Beth, for her unwavering support and encouragement. Her guidance has always brightened my path. I also want to thank my father, Dave, for inspiring my love of nature and sparking my imagination. I thank my siblings, Joe and Adele, as well as my stepfather, Bob, for bringing out the best in me. I would especially like to thank my advisor, Dr. Blaine Griffen. There are no words which can express my gratitude for his brilliant insights, strong mentorship, and extraordinary generosity with time. His dedication and genius are a wellspring of knowledge, and I am honored to have worked under his tutelage. I thank my committee members, Drs. Ryan Rykaczewski, James Pinckney, and Amy Fowler for their service and constructive feedback. They have been invaluable sources of information. I am indebted to the staff of the Baruch Marine Field Laboratory for allowing me to use their facilities and spend my summers at the Hobcaw Barony. I am particularly grateful to Drs. Dennis Allen and Matt Kimball as well as Paul Kenny who have been extremely accommodating and made working in the field a true pleasure. I also want to thank my undergraduate mentors, Drs. Nancy Smith and William Szelistowski, for opening the door into the scientific community and cultivating my skills as a scientist. Lastly, I wish to thank my friends both in South Carolina and across the US who have always been there for me and make life special. iii ABSTRACT Individual variation defines almost every morphological, physiological, and behavioral aspect of populations and is a fundamental component of many ecosystem processes. Recent work indicates that accounting for these individual differences can enhance our ability to predict community responses to environmental disturbances which is becoming increasingly important in an era of extraordinary global change. However, our understanding of how different individual characteristics are connected to each other and governed by the environment remains limited. This study sought to evaluate the relationship between individual behavior, physiological condition, and local habitat for Brachyuran crabs as well as the subsequent strength of their predator-prey interactions within oyster reefs communities. Here, I examined the effects of parasitic infection, diet, habitat quality, season, and conspecific density on crab behavioral traits and physiology. I also evaluated how consistent individual behavioral differences, i.e. personalities, interact with predator type and habitat quality to influence individual mortality and movement patterns. These relationships are essential for calculating population dynamics across multiple spatial scales. My research found that crab energy stores were strongly dependent upon diet and spawning season. In turn, individual crab activity level and reproductive effort were tied to these energy stores and the local environment. Individuals in structurally degraded oyster reefs would generally exhibit lower activity levels and decreased reproductive output in comparison to crabs which inhabited healthy, structurally complex reefs. iv Individual activity was further decreased by reductions in conspecific density, which correlated to habitat quality, and by parasitic infection. Additionally, individual behavior influenced predation risk with bold crabs predominantly consumed by active hunters and shy crabs preferentially selected by ambush predators. Personality also interacted with habitat quality as crabs on low quality reefs rapidly left the region, starting with the boldest individuals; whereas high quality reefs had greater levels of predation, particularly among bold crabs. These findings demonstrate that individual phenotypic variation mediates divergent community interactions across habitat quality and provides several mechanisms through which spatially structured populations may develop. v TABLE OF CONTENTS ACKNOWLEDGEMENTS ...................................................................................................... iii ABSTRACT .......................................................................................................................... iv LIST OF TABLES ................................................................................................................ vii LIST OF FIGURES ..............................................................................................................viii CHAPTER 1 INTRODUCTION ................................................................................................ 1 CHAPTER 2 RHIZOCEPHALAN INFECTION MODIFIES HOST FOOD CONSUMPTION BY REDUCING HOST ACTIVITY LEVELS .................................................................. 7 CHAPTER 3 THE INFLUENCE OF DIET COMPOSITION ON FITNESS OF THE BLUE CRAB, CALLINECTES SAPIDUS .......................................................... 28 CHAPTER 4 INDIVIDUAL PERSONALITY ASSOCIATED WITH INTERACTIONS BETWEEN PHYSIOLOGICAL CONDITION AND THE ENVIRONMENT ....................... 52 CHAPTER 5 HABITAT QUALITY MEDIATES PERSONALITY THROUGH DIFFERENCES IN SOCIAL CONTEXT ...................................................... 76 CHAPTER 6 PREDATOR–PREY INTERACTIONS MEDIATED BY PREY PERSONALITY AND PREDATOR HUNTING MODE .........................................................................101 CHAPTER 7 PERSONALITY INTERACTS WITH HABITAT QUALITY TO GOVERN INDIVIDUAL MORTALITY AND MIGRATION PATTERNS ....................123 CHAPTER 8 CONCLUSION ................................................................................................146 REFERENCES ....................................................................................................................152 APPENDIX A COPYRIGHT PERMISSION LETTERS .............................................................204 vi LIST OF TABLES Table 3.1 Tukey HSD analysis of dietary influence on crab physiology ......................... 47 Table 5.1 Factors influencing crab activity levels ............................................................ 94 Table 5.2 Model estimates of individual effects on behavioral plasticity ........................ 95 vii LIST OF FIGURES Figure 2.1 Effect of parasitic infection on crab gut passage time ..................................... 25 Figure 2.2 Effect of parasitic infection on crab behavior ................................................. 26 Figure 2.3 Effect of parasitic infection on crab habitat use .............................................. 27 Figure 3.1 Effects of diet, feeding time, and temperature on crab behavior ..................... 48 Figure 3.2 Effect of diet on tissue investment towards the hepatopancreas and reproduction .................................................................... 49 Figure 3.3 Relationship between diet, lipid content, and tissue investment towards the hepatopancreas ............................................... 50 Figure 3.4 Effect of diet on egg size ................................................................................. 51 Figure 4.1 Behavior of crabs across habitat quality .......................................................... 70 Figure 4.2 Individual behavior as a product of long-term energy stores and the local environment ..................................................................................... 71 Figure 4.3 Individual behavior as a product of short-term energy stores and the local environment ..................................................................................... 72 Figure 4.4 Individual behavior as a product of body size and the local environment ..................................................................................... 73 Figure 4.5 Reproductive effort of crabs across habitat quality ......................................... 74 Figure 4.6 Relationship between crab reproductive effort and long-term energy stores .................................................................................. 75 Figure 5.1 Crab density within degraded and healthy oyster reefs ................................... 96 Figure 5.2 Effect of predation