Identifying Migration Flexibility and the Environmental Factors That Influence Variation in Recruitment Success in Partially Migratory Hawaiian Fishes
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IDENTIFYING MIGRATION FLEXIBILITY AND THE ENVIRONMENTAL FACTORS THAT INFLUENCE VARIATION IN RECRUITMENT SUCCESS IN PARTIALLY MIGRATORY HAWAIIAN FISHES A Dissertation by HEIDI HEIM-BALLEW BS, Texas A&M University-Corpus Christi, 2015 Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in MARINE BIOLOGY Texas A&M University-Corpus Christi Corpus Christi, Texas May 2019 © Heidi Elizabeth Mae Ballew All Rights Reserved May 2019 IDENTIFYING MIGRATION FLEXIBILITY AND THE ENVIRONMENTAL FACTORS THAT INFLUENCE VARIATION IN RECRUITMENT SUCCESS IN PARTIALLY MIGRATORY HAWAIIAN FISHES A Dissertation by HEIDI HEIM-BALLEW This dissertation meets the standards for scope and quality of Texas A&M University-Corpus Christi and is hereby approved. J. Derek Hogan, PhD Chair David Portnoy, PhD Jennifer Pollack, PhD Committee Member Committee Member Benjamin D. Walther Kent Byus, PhD Committee Member Graduate Faculty Representative May 2019 ABSTRACT Behavior flexibility during the larval stage influences differential mortality, recruitment, and population dynamics; recruitment is poorly understood, yet important for understanding population persistence. The purpose of this dissertation was to examine fishes for migration flexibility and to identify factors at different spatiotemporal scales that are influential to differential survival within and across populations. I found that four underexplored native freshwater fishes of Hawai‘i exhibited a larval migratory strategy, but many were flexible. One species (Sicyopterus stimpsoni) showed all individuals made a migration, and the others showed 25 – 40 % did not migrate. Next, I examined if migrant (S. stimpsoni) and flexible species (Awaous stamineus) showed lunar rhythmicity at hatching and settlement. Migrants of the flexible species showed more hatching around the full moon and settlement around the new moon, and residents showed the opposite pattern. The divergence in life-history timing appears to be a balance between ecological costs and benefits. Next, I examined the influence of variation in localized conditions on the ratio of migrant to resident contingents (A. stamineus) in adult populations. Residents were least represented when stream flow and nutrients were low; however, the abundance of a common invasive predator showed a negative relationship with resident abundance. Highly urbanized systems may impose such stressful conditions that resident recruitment is diminished, which underscores the importance of stream management to conserve vulnerable native species. Lastly, I examined the frequency of contingents (A. stamineus), larval duration, and growth rates across ENSO. The proportion of migrants was highest during La Niña, and resident proportions were highest during weak La Niña and strong El Niño; once El Niño became very strong, resident proportions decreased. Migrants had faster growth than v residents across all growing stages. Migrant growth rates in the early larval stage were highest during El Niño, and pre-settlement growth was highest during La Niña. Resident growth was fastest during neutral conditions. The duration of the early fast-growing period was shortest during El Niño, and the larval duration was longer. These dissertation findings show the importance of evaluating multiple influential scales to understand life-history strategies of individuals, especially those that inhabit multiple ecotypes. vi DEDICATION This work is dedicated to my husband, Daniel, for his unwavering love, support, and encouragement throughout this process. vii ACKNOWLEDGEMENTS I would like to thank my committee chair, Dr. J. Derek Hogan, for offering me the opportunity to continue my academic and professional development and for his confidence in my abilities to be successful. I would like to thank my committee members, Dr. Jennifer Pollack, Dr. Benjamin D. Walther, and Dr. David Portnoy, for their advice and support throughout the course of this research and for their genuine interest in my success. I am also thankful for financial assistance throughout this dissertation from Texas A&M University-Corpus Christi College of Science and Engineering, Marine Biology program, and the National Science Foundation East Asia and Pacific Summer Institutes. Finally, I must thank my family for their loving support and encouragement. I must thank my parents who have always believed in me and instilled in me that hard work makes anything possible. I am thankful for the strong women in my family, my mamaw Susie Barry, my grandmother Mildred Hortenberry, my mother Vicki Stewart, and my sister Heather Heim- Lawson, for helping raise me, inspiring me, and teaching me about inner strength, work ethic, and the ability to overcome all odds. My gratitude for my husband, Daniel, cannot be overstated. He stood beside and with me throughout this journey and always encouraged me to push forward. Our two dogs, Dexter and Tucker, provided the best companionship while analyzing data and writing over the past four years. Without all of these people, this would not have been possible. viii TABLE OF CONTENTS CONTENTS PAGE ABSTRACT .................................................................................................................................... v DEDICATION .............................................................................................................................. vii ACKNOWLEDGEMENTS ......................................................................................................... viii TABLE OF CONTENTS ............................................................................................................... ix LIST OF FIGURES .................................................................................................................... xiiii LIST OF TABLES ...................................................................................................................... xvii INTRODUCTION .......................................................................................................................... 1 REFERENCES ............................................................................................................................... 5 CHAPTER 1: FACULTATIVE MIGRATION IS COMMON IN HAWAI‘I’S NATIVE FRESHWATER FISHES ............................................................................................................... 9 Abstract .................................................................................................................................. 9 Introduction .......................................................................................................................... 10 Methods................................................................................................................................ 15 Results .................................................................................................................................. 20 Discussion ............................................................................................................................ 24 REFERENCES .................................................................................................................... 33 CHAPTER 2: VARIABLE LUNAR RHYTHMYCITY WITHIN AND AMONG NATIVE HAWAIIAN AMPHIDROMOUS FISHES ................................................................................. 42 Abstract ................................................................................................................................ 42 ix Introduction .......................................................................................................................... 43 Methods................................................................................................................................ 46 Results .................................................................................................................................. 52 Discussion ............................................................................................................................ 58 REFERENCES .................................................................................................................... 64 CHAPTER 3: FACTORS THAT INFLUENCE DIFFERENTIAL SURVIVAL OF RESIDENTS OF A MIGRATORY HAWAIIAN FRESHWATER FISH ACROSS ENVIRONMENTAL AND BIOLOGICAL GRADIENTS ...................................................................................................... 72 Abstract ................................................................................................................................ 72 Introduction .......................................................................................................................... 73 Methods................................................................................................................................ 79 Results .................................................................................................................................. 86 Discussion ............................................................................................................................ 89 REFERENCES .................................................................................................................... 97 CHAPTER 4: CLIMATIC VARIATION INFLUENCES RECRUITMENT SUCCESS AND GROWTH OF DIFFERENT LIFE-HISTORIES IN A FACULTATIVELY MIGRATORY HAWAIIAN FISH .....................................................................................................................