The development of diving behavior and physiology in juvenile Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica Item Type Thesis Authors Burns, Jennifer Moss Download date 23/09/2021 10:53:47 Link to Item http://hdl.handle.net/11122/9468 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely afreet reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. 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Further reproduction prohibited without permission. THE DEVELOPMENT OF DIVING BEHAVIOR AND PHYSIOLOGY IN JUVENILE WEDDELL SEALS (LEPTONYCHOTES WEDDELLIf) IN MCMURDO SOUND, ANTARCTICA A THESIS Presented to the Faculty of the University of Alaska Fairbanks In Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Jennifer Moss Bums, B.S., M.S. Fairbanks, Alaska August 1997 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 9804764 UMI Microform 9804764 Copyright 1997, by UMI Company. Ail rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. 300 UMINorth Zeeb Road Ann Arbor, MI 48103 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THE DEVELOPMENT OF DIVING BEHAVIOR AND PHYSIOLOGY IN JUVENILE WEDDELL SEALS (LEPTONYCHOTES WEDDELLII) IN MCMURDO SOUND, ANTARCTICA By Jennifer Moss Bums r RECOMMENDED: ^ r Advisory Committee Chair Department Head ' V APPROVED: \ 1 JBL Dean, School of Fisheries and Ocean Sciences 3p«mof the Graduate School V 9"7 Date Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iii ABSTRACT The development of diving behavior and physiology in juvenile Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica was studied in order to determine the effects of age, body size, and condition on diving ability. During the austral summers of 1992,1993, and 1994, the diving behavior of 39 pups and 15 yearlings was monitored using time depth recorders (TDRs). In addition, 26 pups were equipped with satellite-linked time depth recorders (SLTDRs) to track fall and winter diving behavior. Blood samples and morphological measurements were taken at each handling. Pups began to dive within two weeks of birth, and the mean dive depth, duration, and number of dives per day increased significantly over the next 10 weeks. During this period, the ability of pups to regulate physiological processes related to diving increased, as did their aerobic dive limit (ADL). Whereas diving behavior was determined primarily by age rather than mass in young pups, age had little effect on the diving behavior of pups older than 2 months (as determined from SLTDR records). Because seals were not handled after SLTDR deployment, the effects of mass could not be directly modeled in these pups. However, in yearlings, the ADL, and approximately 50% of the variation in dive behavior could be explained by differences in body size. Most dive parameters differed by time of day, and deeper and longer dives were more frequent in the afternoon period. The diel pattern was consistent with the hypothesis that pups were foraging throughout the day on vertically migrating prey species. In yearlings, dive patterns suggested that large individuals foraged primarily on shallow water prey, while smaller animals concentrated on deeper prey such as Antarctic silverfish. Tracking studies revealed that juveniles were capable of long distance movements, but suggested that they remained closer to the coastline than adults. The absence of obvious differences in dive behavior between regions suggested that juveniles were foraging on similar prey throughout the Ross Sea. While scat analyses confirmed this hypothesis, tissue stable isotope ratios suggested that some juveniles were feeding on different prey, or in different areas than adults. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents List of Figures..................................................................................................................................viii List of Tables.......................................................................................................................................x List of Abbreviations ...................................................................................................................... xii Acknowledgments ..........................................................................................................................xiii Preface ................................................................................................................................................xv Chapter 1. Introduction ..................................................................................................................... 1 DIVING PHYSIOLOGY.................................................................................................................... 3 WEDDELL SEAL BIOLOGY AND ECOLOGY.............................................................................. 5 SCOPE OF THE STUDY.................................................................................................................7 LITERATURE CITED......................................................................................................................10 Chapter 2: Developmental changes and diumal and seasonal influences on the diving behavior of Weddell seal (Leptonychotes weddellii) pups....................................................... 15 ABSTRACT..................................................................................................................................... 15 INTRODUCTION............................................................................................................................ 16 METHODS...................................................................................................................................... 17 RESULTS........................................................................................................................................ 19 DISCUSSION................................................................................................................................. 21 ACKNOWLEDGMENTS................................................................................................................24 LITERATURE CITED..................................................................................................................... 29 Chapter 3: Physiological and behavioral determinants of the aerobic dive limit in Weddell seal (Leptonychotes weddellii) p u p s .......................................................................................... 32 ABSTRACT.....................................................................................................................................32 INTRODUCTION............................................................................................................................ 33 METHODS......................................................................................................................................34 Animal Handling..........................................................................................................................34 Blood Collection and Analysis ...................................................................................................35 Dive Data.....................................................................................................................................36 ADL Determinations................................................................................................................... 36 Diving Metabolic Rates ..............................................................................................................37 RESULTS.......................................................................................................................................