The physiological responses of King George whiting to a changing environment Nastaran Mazloumi Presented for the degree of Doctor of Philosophy School of Biological Sciences The University of Adelaide September 2015 1 Table of Contents Chapter 1: General Introduction .............................................................................................. 12 Environmental variability and its effects on aquatic ectotherms ......................................... 13 Temperature change ............................................................................................................. 13 Salinity ................................................................................................................................. 14 Dissolved Oxygen .................................................................................................................... 15 El Niño Southern Oscillation Index ......................................................................................... 15 Methods to assess effects of environmental variation on aquatic ectotherms...................... 16 Otolith chemistry and environmental reconstruction ........................................................... 18 Swim respirometry ............................................................................................................... 20 Critical swimming performance (Ucrit) in response to temperature and salinity .................. 20 Metabolic response to temperature ...................................................................................... 21 Overview of the study species .............................................................................................. 22 Biology and ecology of King George whiting ..................................................................... 22 Fisheries status in South Australia ....................................................................................... 24 Principle objective ............................................................................................................ 24 Specific objectives ............................................................................................................ 25 Notes on structure and style .............................................................................................. 25 Chapter 2: Determining climate-growth relationships in a temperate fish: a sclerochronological approach .................................................................................................. 40 Abstract .................................................................................................................................... 42 Introduction .............................................................................................................................. 43 Materials and Methods ............................................................................................................. 44 Sample collection ................................................................................................................. 44 Otolith preparation and growth estimation........................................................................... 45 Growth predictors ................................................................................................................. 48 Modelling approach.............................................................................................................. 51 2 Results ...................................................................................................................................... 54 Discussion ................................................................................................................................ 59 Conclusion ............................................................................................................................... 62 Acknowledgements .................................................................................................................. 63 References ................................................................................................................................ 64 Chapter 3: The influence of temperature on the metabolic rate and swimming speed of a temperate fish ........................................................................................................................... 69 Abstract .................................................................................................................................... 71 Introduction .............................................................................................................................. 72 Material and Methods .............................................................................................................. 74 Fish collection and maintenance .......................................................................................... 74 Measurement of critical swimming speed ............................................................................ 75 Measurement of metabolic rate ............................................................................................ 76 Statistical analysis ................................................................................................................ 78 Results ...................................................................................................................................... 78 Discussion ................................................................................................................................ 81 The effect of temperature change on critical swimming speed (Ucrit).................................. 81 Maximum metabolic rate (MMR) and standard metabolic rate (SMR) in response to elevated temperature ............................................................................................................ 82 The effect of elevated water temperature on aerobic scope of activity and recovery time .. 84 Conclusion ............................................................................................................................... 85 Acknowledgements .................................................................................................................. 86 References ................................................................................................................................ 87 Chapter 4: Metabolic rate and swimming behaviour of a juvenile temperate fish in relation to temperature and salinity ........................................................................................................... 94 Abstract .................................................................................................................................... 96 Introduction .............................................................................................................................. 98 Methodology .......................................................................................................................... 100 3 Fish collection .................................................................................................................... 100 Experimental procedures .................................................................................................... 102 Metabolic rate measurement .............................................................................................. 103 Swimming performance ..................................................................................................... 104 Temperature quotient calculations (Q10) ............................................................................ 105 Statistical analysis .............................................................................................................. 105 Results .................................................................................................................................... 106 Discussion .............................................................................................................................. 114 Temperature and salinity effects on aerobic metabolic rate ............................................... 114 Salinity effect on Ucrit and SMR ......................................................................................... 118 Conclusion ............................................................................................................................. 119 Acknowledgements ................................................................................................................ 120 References .............................................................................................................................. 121 Chapter 5: The effects of temperature and salinity on otolith chemistry of King George whiting ................................................................................................................................... 130 Abstract .................................................................................................................................. 132 Introduction ............................................................................................................................ 133 Methodology .......................................................................................................................... 135 Study species 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