Population Structure and Movement of Black Bream (Acanthopagrus butcheri) in South Australian Estuaries Based on Otolith Chemistry Ana Judith Giraldo Presented for the degree of Doctor of Philosophy School of Biological Sciences University of Adelaide July 2015 Declaration I certify that this work contains no material which has been accepted for the award of any other degree or diploma in my name, in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. In addition, I certify that no part of this work will, in the future, be used in a submission in my name, for any other degree or diploma in any university or other tertiary institution without the prior approval of the University of Adelaide and where applicable, any partner institution responsible for the joint-award of this degree. I give consent to this copy of my thesis, when deposited in the University Library, being made available for loan and photocopying, subject to the provisions of the Copyright Act 1968. I also give permission for the digital version of my thesis to be made available on the web, via the University’s digital research repository, the Library Search and also through web search engines, unless permission has been granted by the University to restrict access for a period of time. Ana Judith Giraldo July 2015 Cover image: Black bream ecosystem (watercolour by Gustavo Giraldo & Judith Giraldo) 2 “This is what knowledge really is. It is finding out something for oneself with pain, with joy, with exultancy, with labour, and with all the little ticking, breathing moments of our lives, until is ours which is rooted in the structure of our lives” Thomas Wolfe (1900-1938) 3 Table of Contents Declaration ............................................................................................................................................ 2 Table of Contents .................................................................................................................................. 4 Abstract ................................................................................................................................................. 8 Acknowledgements ............................................................................................................................. 10 Chapter Acknowledgements ............................................................................................................ 11 Chapter 1. General Introduction .......................................................................................................... 13 Estuaries .......................................................................................................................................... 13 Use of estuaries by fish ................................................................................................................... 15 Determining population structure and connectivity ........................................................................ 18 Otolith chemistry for determining population structure and movements of fish ............................. 19 Objectives ........................................................................................................................................ 20 Study area – Fleurieu Peninsula and Kangaroo Island .................................................................... 22 Characteristics of Kangaroo Island and Southern Fleurieu estuaries .............................................. 22 Fishes of Kangaroo Island ............................................................................................................... 28 Study species – Acanthopagrus butcheri......................................................................................... 28 Chapter 2 – Statement of authorship ................................................................................................... 31 Chapter 2. Temporal and spatial variability in otolith elemental composition: a precursor for determining population connectivity ................................................................................................... 33 Abstract ........................................................................................................................................... 34 Introduction ..................................................................................................................................... 35 Materials and Methods .................................................................................................................... 36 Sample collection ........................................................................................................................ 36 Otolith preparation....................................................................................................................... 38 Otolith chemical analysis ............................................................................................................ 38 4 Statistical analyses....................................................................................................................... 39 Results ............................................................................................................................................. 40 Temporal differences ................................................................................................................... 42 Spatial differences ....................................................................................................................... 42 Discussion ....................................................................................................................................... 50 Temporal and spatial variation in otolith chemistry .................................................................... 50 Grouping of estuaries and applications for describing stocks ..................................................... 52 Conclusion....................................................................................................................................... 54 Chapter 3 – Statement of authorship ................................................................................................... 56 Chapter 3. Temporal patterns of connectivity between juvenile and subadult areas inferred from otolith elemental fingerprints .............................................................................................................. 58 Abstract ........................................................................................................................................... 59 Introduction ..................................................................................................................................... 60 Materials and methods .................................................................................................................... 61 Sample collection ........................................................................................................................ 61 Otolith preparation ...................................................................................................................... 62 Age estimation and assignment of annual recruitment cohort .................................................... 63 Multielemental otolith analyses .................................................................................................. 63 Statistical analyses....................................................................................................................... 65 Results ............................................................................................................................................. 67 Juvenile otolith signatures ........................................................................................................... 67 Temporal contributions of recruits .............................................................................................. 68 Temporal patterns of connectivity ............................................................................................... 69 Discussion ....................................................................................................................................... 71 Conclusion....................................................................................................................................... 75 5 Chapter 4 – Statement of authorship ................................................................................................... 76 Chapter 4. Partial migration in black bream from different estuaries on Kangaroo Island: do migratory fish represent a hybrid complex? ........................................................................................ 78 Abstract ........................................................................................................................................... 79 Introduction ..................................................................................................................................... 80 Materials and Methods .................................................................................................................... 82 Study species ..............................................................................................................................