The role of post-settlement processes in determining fouling assemblages on artificial reefs By Shea Rohan Cameron Thesis Submitted to Flinders University for the degree of PhD Science and Engineering 26.11.2018 1 “Without basing a reef’s construction upon proper scientific principles it becomes at best a temporary high relief area of questionable value, or at worst an ocean junk pile whose major value has been as a promotional gimmick publicizing a special interest group” Turner et al. 1969 2 TABLE OF CONTENTS SUMMARY ............................................................................................................................ 6 ACKNOWLEDGEMENTS ................................................................................................... 9 DECLARATION ................................................................................................................. 11 CHAPTER 1. GENERAL INTRODUCTION .................................................................. 12 1.1 Background .............................................................................................................................. 12 1.2 Pre- and Post- Settlement Processes and Fouling assemblages ................................................ 13 1.3 Disturbances in fouling assemblages ........................................................................................ 16 1.4 Fouling Assemblages on Artificial Substrates ............................................................................ 18 1.5 Studying assemblages on Artificial reefs................................................................................... 21 1.6 The use of artificial reefs in South Australia ............................................................................. 23 1.7 Study Objectives and thesis Structure ...................................................................................... 24 CHAPTER 2. METHOD MATTERS IN THE DETECTION OF DIFFERENCES IN FOULING ASSEMBLAGES .............................................................................................. 26 2.1 Introduction ............................................................................................................................. 26 2.2 Materials & Methods ............................................................................................................... 30 2.2.1 Study Sites ............................................................................................................................... 30 2.2.2 Sampling Methodology ........................................................................................................... 33 2.2.3 Statistical analysis ................................................................................................................... 34 2.3 Results...................................................................................................................................... 36 2.3.1 Comparison of diversity assessment between methods ........................................................ 36 2.3.2 Comparison of abundance assessments Between methods .................................................. 41 2.3.3 Comparison of fouling assemblages between methods and taxonomic levels ...................... 44 2.4. Discussion ............................................................................................................................... 52 2.4.1 Comparisons of the two sampling methods ........................................................................... 52 2.4.2 Recommendations on sampling methods .............................................................................. 55 CHAPTER 3. A COMPARISON OF FOULING ASSEMBLAGES ON NATURAL AND ARTIFICIAL REEFS IN THE GULF OF ST VINCENT. ..................................... 59 3.1 Introduction ............................................................................................................................. 59 3.2 Materials and Methods ............................................................................................................ 63 3.2.1 Study Sites ............................................................................................................................... 63 3 3.2.2 Sampling methods and analysis .............................................................................................. 65 3.2.3 Data Analysis ........................................................................................................................... 66 3.3 Results...................................................................................................................................... 68 3.3.1 Sampled flora and fauna ......................................................................................................... 68 3.3.2 Abundances of colonial invertebrates and macroalgae ......................................................... 73 3.3.3 Abundances of non-colonial invertebrates ............................................................................. 77 3.3.4 Regional and small scale differences in fouling assemblages on wooden jetties ................... 77 3.3.5 Similarity of Assemblages between substrates ...................................................................... 79 3.3.6 Relationship between Epibiotic structural groups and non colonial macro-invertebrates. ... 83 3.4 Discussion ................................................................................................................................ 86 3.4.1 Discussion of assemblages on substrate types ....................................................................... 88 3.4.2 Recommendations for comparisons ....................................................................................... 91 CHAPTER 4. SEASONAL RECRUITMENT VS. SUBSTRATE PREFERENCES OF RECRUITING LARVAE AT FOUR SITES IN THE GULF ST VINCENT. ................. 93 4.1 Introduction ............................................................................................................................. 93 4.2. Methods .................................................................................................................................. 97 4.2.1 Sites and Experimental procedure .......................................................................................... 97 4.2.2 Sample Analysis .................................................................................................................... 100 4.2.3 Statistical analysis ................................................................................................................. 100 4.3. Results................................................................................................................................... 101 4.3.1 Diversity of Assemblages ...................................................................................................... 101 4.3.2 Multivariate analyses ............................................................................................................ 106 4.3.2.1 Colonial invertebrates and macroalgae ............................................................................. 106 4.3.2.2 Non-colonial macroinvertebrate assemblages .................................................................. 108 4.3.3 Testing hypotheses using CAP for both assemblages ........................................................... 110 4.4. Discussion ............................................................................................................................. 114 CHAPTER 5. BIOGENIC STRUCTURES FACILITATE RECRUITMENT ON ARTIFICIAL REEFS. ...................................................................................................... 119 5.1. Introduction .......................................................................................................................... 119 5.2 Methods and Materials .......................................................................................................... 124 5.2.1 Study Sites ............................................................................................................................. 124 5.2.2 Experimental procedure ....................................................................................................... 125 5.2.3 Functional classification ........................................................................................................ 127 5.2.4 Data Analysis ......................................................................................................................... 128 5.3. Results................................................................................................................................... 129 5.3.1 Taxonomic diversity of invertebrates and algae ................................................................... 129 5.3.2 Functional group diversity ................................................................................................... 130 5.3.2. Abundances of invertebrates ............................................................................................... 133 5.3.3 Abundances of functional groups of macroinvertebrates .................................................... 135 5.3.4 Assemblages of non-colonial invertebrates .......................................................................... 138 5.3.4 Assemblages of Functional Groups ....................................................................................... 138 5.4. Discussion ............................................................................................................................