Reproductive biology of the western king prawn Penaeus (Melicertus) latisulcatus (Kishinouye 1896) in Spencer Gulf and Gulf St Vincent, South Australia Nadine Emily Hackett B. Science., Hons. Marine Biology A thesis submitted in fulfilment for the degree of Doctor of Philosophy School of Biological Sciences Faculty of Science and Engineering Flinders University of South Australia March 2017 Table of Contents Summary ............................................................................................................................... i Declaration .......................................................................................................................... iii Acknowledgements ............................................................................................................. iv Chapter 1: General Introduction 1.1 Diversity of life history strategies among marine invertebrates .................................... 6 1.2 Reproduction and general biology of penaeids ............................................................ 8 1.3 Biology of Penaeus (Melicertus) latisulcatus (Kishinouye 1896) ................................ 11 1.4 Environmental variation and reproductive strategies.................................................. 12 1.5 Thesis scope and outline ............................................................................................ 13 Part 1: Ovarian stages Chapter 2: Microscopic analysis of ovarian stages of the western king prawn Penaeus (Melicertus) latisulcatus (Kishinouye 1896) 2.1 Abstract ....................................................................................................................... 15 2.2 Introduction ................................................................................................................. 15 2.3 Materials and methods ............................................................................................... 16 2.3.1 Sample collection ................................................................................................. 16 2.3.2 Fixation and histological analysis of specimens .................................................. 17 2.4 Results ........................................................................................................................ 18 2.4.1 Histological stages ............................................................................................... 18 2.5 Discussion ................................................................................................................... 26 Chapter 3: Postovulatory follicles in a penaeid prawn: detection and histological classification of degeneration 3.1 Abstract ....................................................................................................................... 27 3.2 Introduction ................................................................................................................. 27 3.3 Materials and methods ............................................................................................... 30 3.3.1 Collection of P. latisulcatus .................................................................................. 30 3.3.2 Laboratory based experiments ............................................................................ 31 3.3.3 Histological analysis of ovaries ............................................................................ 34 3.3.4 Data analysis ....................................................................................................... 35 3.4 Results ........................................................................................................................ 35 3.4.1 Relationship between carapace length and ovary weight ................................... 35 3.4.2 Description of histological change in POF degeneration ..................................... 36 3.5 Discussion ................................................................................................................... 45 Chapter 4: Validity of visual determination of ovary development stages of the western king prawn Penaeus (Melicertus) latisulcatus (Kishinouye 1896) 4.1 Abstract ....................................................................................................................... 48 4.2 Introduction ................................................................................................................. 48 4.3 Materials and methods ............................................................................................... 52 4.3.1 Sample collection and macroscopic staging ....................................................... 52 4.3.2 Comparison of macroscopic and microscopic staging ........................................ 52 4.4 Results ........................................................................................................................ 53 4.4.1 Comparison between macroscopic and microscopic staging.............................. 53 4.4.2 Individual observer-validation .............................................................................. 54 4.5 Discussion ................................................................................................................... 57 Part II Reproductive biology Chapter 5 Reproductive biology of the western king prawn (Penaeus (Melicertus) latisulcatus Kishinouye, 1896) in a temperate environment 5.1 Abstract ....................................................................................................................... 61 5.2 Introduction ................................................................................................................. 61 5.3 Materials and methods ............................................................................................... 66 5.3.1 Sample collection ................................................................................................. 66 5.3.2 Histological determination of ovarian maturity stage ........................................... 69 5.3.3 Reproductive analyses ........................................................................................ 69 5.3.4 Data analysis ....................................................................................................... 70 5.4 Results ........................................................................................................................ 70 5.4.1 Length – weight relationship ................................................................................ 70 5.4.2 Gonadosomatic index and fecundity ................................................................... 72 5.4.3 Physiological maturity .......................................................................................... 73 5.4.4 Insemination rates ............................................................................................... 74 5.4.5 Percent ripe ......................................................................................................... 74 5.4.6 Histological validation of ovarian stage ............................................................... 78 5.5 Discussion ................................................................................................................... 79 5.5.1 Total length - weight relationship ......................................................................... 79 5.5.2 GSI and fecundity ................................................................................................ 80 5.5.3 Insemination and Physiological maturity ............................................................. 81 5.5.4 Percent ripe ......................................................................................................... 82 5.5.5 Histological Validation of ovarian stage ............................................................... 83 Chapter 6: Assessment of postovulatory follicle degeneration in wild caught western king prawns, Penaeus (Melicertus) latisulcatus (Kishinouye 1896), in Spencer Gulf, South Australia 6.1 Abstract ....................................................................................................................... 85 6.2 Introduction ................................................................................................................. 85 6.3 Materials and methods ............................................................................................... 88 6.3.1 Collection of P. latisulcatus .................................................................................. 88 6.3.2 Histological classification ..................................................................................... 89 6.3.3 Spawning Occurrence ......................................................................................... 90 6.3.4 Data analysis ....................................................................................................... 90 6.4 Results ........................................................................................................................ 91 6.4.1 Postovulatory follicle presence in female P. latisulcatus ..................................... 91 6.4.2 Spawning Occurrence ......................................................................................... 93 6.5 Discussion ................................................................................................................... 96 Chapter 7: General Discussion References 8.1 References ...............................................................................................................