LATITUDINAL VARIATION IN NATICID GASTROPOD PREDATION ON WESTERN ATLANTIC MOLLUSKS: INVESTIGATING EVOLUTIONARY PATTERNS IN THE FOSSIL RECORD THROUGH MODERN ECOSYSTEMS Christy C. Visaggi A Dissertation Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Department of Biology and Marine Biology University of North Carolina Wilmington 2012 Approved by Advisory Committee Gregory P. Dietl Martin H. Posey . Richard A. Laws Stuart R. Borrett . Patricia H. Kelley . Chair Accepted by . Dean, Graduate School TABLE OF CONTENTS ABSTRACT .....................................................................................................................................v ACKNOWLEDGMENTS ............................................................................................................ vii DEDICATION ............................................................................................................................. viii LIST OF TABLES ......................................................................................................................... ix LIST OF FIGURES .........................................................................................................................x CHAPTER ONE: Overview ............................................................................................................1 References ..................................................................................................................................5 CHAPTER TWO: Equatorward Increase in Naticid Gastropod Drilling Predation on Infaunal Bivalves from Brazil ........................................................................................................................7 Abstract ......................................................................................................................................7 Introduction ................................................................................................................................8 Biogeographic Setting ........................................................................................................12 Methods....................................................................................................................................15 Field Collection ..................................................................................................................15 Laboratory Techniques ......................................................................................................19 Data Analysis .....................................................................................................................20 Results ......................................................................................................................................22 Assemblage Analyses ........................................................................................................22 Lower Taxon Analyses ......................................................................................................22 Size-Standardized Analyses ...............................................................................................27 Incomplete and Multiple Drilling ......................................................................................31 Discussion ................................................................................................................................34 Overall Patterns in Drilling Predation................................................................................34 Potential Biases and Limitations of the Data .....................................................................37 Environmental Variation ..............................................................................................37 Sampling Methods .......................................................................................................39 Anthropogenic Effects .................................................................................................42 Preservational Factors ..................................................................................................45 Western Atlantic: North vs. South .....................................................................................46 Temperature and Seasonality .......................................................................................50 Naticid Diversity ..........................................................................................................53 Alternate Modes of Predation ......................................................................................57 Predator-Prey Size Distributions..................................................................................58 Prey Diversity ..............................................................................................................59 Paleontological Implications ..............................................................................................61 ii Future Work .......................................................................................................................65 Conclusions ..............................................................................................................................66 Acknowledgments....................................................................................................................67 References ................................................................................................................................68 CHAPTER THREE: Examining the Influence of Seasonality on Naticid Drilling Predation Using an Experimental Approach in Both a Laboratory and Field Setting ...................................75 Abstract ....................................................................................................................................75 Introduction ..............................................................................................................................76 Setting ......................................................................................................................................78 Methods: Laboratory ................................................................................................................81 Data Collection: Predators .................................................................................................84 Data Collection: Prey .........................................................................................................84 Natural Mortality and Decay .............................................................................................84 Methods: Field .........................................................................................................................87 Recovery of Specimens......................................................................................................88 Data Analysis .....................................................................................................................88 Results: Lab .............................................................................................................................89 Natural Mortality and Decay .............................................................................................94 Results: Field ...........................................................................................................................95 Discussion ..............................................................................................................................100 Potential Biases ................................................................................................................105 Laboratory Experiments.............................................................................................105 Field Experiments ......................................................................................................112 Seasonal Variation ...........................................................................................................115 Fall vs. Spring ............................................................................................................115 Field vs. Lab: Summer ...............................................................................................117 Latitudinal Patterns ..........................................................................................................119 Paleontological Implications ............................................................................................123 Future Work .....................................................................................................................125 Conclusions ............................................................................................................................126 Acknowledgments..................................................................................................................127 References ..............................................................................................................................128 CHAPTER FOUR: Influence of Sediment Depth on Drilling Behavior of Neverita duplicata (Gastropoda: Naticidae) With a Review of Alternate Modes of Predation .................................133 Abstract ..................................................................................................................................133