University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2000 Structure and dynamics of sponge-dominated assemblages on the temperate reefs: variability associated with anthropogenic disturbance Daniel E. Roberts University of Wollongong Recommended Citation Roberts, Daniel E., Structure and dynamics of sponge-dominated assemblages on the temperate reefs: variability associated with anthropogenic disturbance, Doctor of Philosophy thesis, Department of Biological Sciences, University of Wollongong, 2000. http://ro.uow.edu.au/theses/1870 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] STRUCTURE AND DYNAMICS OF SPONGE- DOMINATED ASSEMBLAGES ON TEMPERATE REEFS: VARIABILITY ASSOCIATED WITH ANTHROPOGENIC DISTURBANCE A thesis submitted in fulfilment of the requirements for the award of the degree DOCTOR OF PHILOSOPHY from UNIVERSITY OF WOLLONGONG by Daniel E. Roberts Department of Biological Sciences 2000 11 FRONTISPIECE: Sponge-dominated assemblage from a temperate reef at 50m depth (Sydney, NSW, Australia). Ill DECLARATION I, Daniel E. Roberts, declare that this thesis, submitted in fulfilment of the requirements for the award of Doctor of Philosophy, in the Department of Biological Sciences, University of Wollongong, is wholly my own work unless otherwise referenced or acknowledged. The document has not been submitted for qualifications at any other academic institution. Daniel Edward Roberts November 2000 iv TABLE OF CONTENTS Acknowledgements vi Papers and Manuscripts Associated with Thesis Chapters viii Papers and Reports Associated with Thesis ix Abstract x List of Tables xiv List of Figures xviii CHAPTER 1: GENERAL INTRODUCTION 1 CHAPTER 2: GENERAL METHODS 5 STUDY AREA 5 QUANTIFYING SUBTIDAL ASSEMBLAGES 8 Introduction 8 Methods 10 Jump Camera 10 Analysis of Photographs 11 Comparison of Jump Camera with in situ Sampling 11 Results 15 Discussion 21 TAXONOMIC DISCRIMINATION 25 Introduction 25 Methods 28 Univariate Assessment 30 Multivariate Assessment 31 Results 32 Univariate Approach 33 Taxonomic resolution within kelp forests 33 Taxonomic resolution within crustose coralline habitats 33 Statistical power and taxonomic resolution 34 Multivariate Approach 38 Taxonomic resolution within kelp forests 38 Taxonomic resolution within crustose coralline habitats 40 Discussion 44 CHAPTER 3: PATTERNS OF NATURAL VARIABILITY 48 DEPTH RELATED PATTERNS IN SPONGE ASSEMBLAGES 48 Introduction 48 Methods 49 Study Sites and Sampling 49 Statistical Treatment of Data 50 Results 53 Species Distribution and Composition 53 Total Sponge Richness and Cover 58 Comparison Between Erect and Encrusting Forms 58 Discussion 65 STRUCTURE AND DYNAMICS ON EXPOSED AND SHELTERED REEFS 68 Introduction 68 Methods 70 Study Locations and Sampling Design 70 Analysis of Photographs and Taxonomic Discrimination 72 Univariate Statistical Analyses 72 Multivariate Statistical Analyses 73 Results 74 Changes in Richness and Cover 74 Changes in Community Structure 79 Discussion 82 V CHAPTER 4: PATTERNS ASSOCIATED WITH SEWAGE DISPOSAL 86 SHALLOW-WATER ASSEMBLAGES IN KELP FORESTS 86 Introduction 86 Methods 88 Results 92 Univariate Analyses 92 Algal assemblages 92 Faunal assemblages 93 Multivariate Analyses 99 Discussion 104 NEARSHORE SPONGE-DOMINATED ASSEMBLAGES 108 Introduction 108 Methods 110 Study Locations and Sampling Design 110 Analysis of Photographs and Taxonomic Discrimination 111 Univariate Statistical Analyses 113 Multivariate Statistical Analyses 115 Results 115 Changes in Cover and Richness 116 Taxa which showed little change at the outfall 116 Taxa which decreased at the outfall 117 Taxa which increased at the outfall 121 Changes in Community Structure 124 Discussion 129 SPONGE-DOMINATED ASSEMBLAGES IN DEEP-WATER 133 Introduction 133 Methods 134 Results 140 Discussion 150 CHAPTER 5: SEWAGE-RELATED PROCESSES 156 Introduction 156 Methods 159 Study Sites and Sponge Handling 159 Experimental Design 161 Laboratory Procedures 162 Analyses of Data 163 Results 164 Sponge Growth 164 Reproductive Status 165 Symbiotic Algae 167 Discussion 180 CHAPTER 6: GENERAL DISCUSSION 184 SPATIAL AND TEMPORAL VARIABILITY 184 EFFECTS OF SEWAGE 188 MANAGEMENT CONSIDERATIONS 191 REFERENCES 194 VI Acknowledgements As the year 2000 drew to a close, I seriously considered changing the title of this thesis to "2001: A Sponge Odyssey". In retrospect, I was quite naive about the significant amount of time that I would need to devote to this research. Some said that trying to do a PhD whilst working full time would be very difficult if not impossible. At times I had to agree, especially when it came to the amount of time that I needed to spend on the most tedious of tasks, and especially when I realised just how much I actually did not know. Many difficult but enjoyable times were ahead, and I met many new friends and colleagues along the way. The support of these colleagues and friends made the task achievable and worthwhile. Most of the chapters in this thesis have now been published or are in the process of being published and the contributions of co-author(s) in each of the various papers are duly acknowledged: Andy Davis, Sharon Cummins, Steve Fitzhenry, Steve Kennelly, Tony Roach, Peter Scanes, Adam Smith and Penny Ajani. Much of the earlier work done in this thesis was logistically possible because of the support given by management and colleagues from the NSW Environment Protection Authority (EPA). In particular I would like to thank Gary Henry, Tony Church, Peter Scanes, Klaus Koop, Ross Higginson, David Leece, Robin Macdonald and Neil Philip. Colleagues from the Water Studies Section (EPA) are also thanked for their valuable assistance over the years, in particular, Scott Carter, Peter Scanes, Tony Roach, Stuart Puckeridge, Martin Krogh, Penny Ajani, Graham Sherwin, Rob Smith and Chris Pangway. Last, but not least, I would particularly like to thank Sharon Cummins for her advice and assistance throughout the work done in this thesis, and her expertise in fending off the white pointer sharks and the marauding yachties. vii The following colleagues have also, at some stage, either assisted in reviews of manuscripts or been substantially involved with some aspect of the research done in this thesis and they are all acknowledged for their valuable contributions: Dan Fitzhenry, Paul McGaw, Steve Fitzhenry, Adam Fitzhenry, Yvette Eckersley, Adam Smith, John Hooper, Steve Kennelly, Tony Underwood, Marcus Lincoln-Smith, Alan Jones, David Ayre, Rob Whelan, Alan Butler, Brian Bayne, Clive Wilkinson, Peter Fairweather, Phil Colman, Kirsten Benkendorff, Geoff Sainty, Paul Somerfield, Ken Zimmerman, Shane Murray, Bob Diaz, Karla Casey, Sian Towel. I would also like to thank my "fish-widow" mum (Jan Roberts) and "so long and thanks for all the fish" dad (Bob Roberts), for inspiring in me a love of the sea and all those smelly wriggly bits in it. Dad is also thanked for his advice and help in constructing the treatment cages for the experimental work. The support and significant contributions of my wife (Jan) and children (Nicholas, William, Ella and Ethan) throughout this thesis was most appreciated, as I know they gained a "sponge nerd" for a few years. Before starting my PhD, I was given a fundamental piece of advice - "what determines whether your PhD is typical or exceptional will be somewhat reflected by the expertise, enthusiasm and wisdom of your supervisor - so get a good one". I certainly took that advice when I chose my supervisor -1 sincerely thank Associate Professor Andy (Aza) Davis whom through his sage advice, genuine enthusiasm and good humour made the whole thing possible (although I am still a little confused about the relevance of underwater goats in subtidal assemblages). Vlll Papers and Manuscripts Associated with Thesis Chapters CHAPTER 2 - General Methods Roberts, D. E., Fitzhenry, S. R., Kennelly, S. J. (1994). Quantifying subtidal macrobenthic assemblages on hard substrata using a jump camera method. J. Exp. Mar. Biol. Ecol. 177: 157-170. Roberts, D. E., Roach, A. C. (2000). Taxonomic sufficiency in detecting the effects of sewage on subtidal macrobenthic assemblages on hard substrata. Mar. Poll. Bull. In press. CHAPTER 3 - Patterns of Variability Roberts, D. E., Davis, A. R. (1996). Patterns in sponge (Porifera) assemblages on temperate coastal reefs off Sydney, Australia. Mar. Freshwater Res. 47: 897-906. Roberts, D. E. (2000). Spatial and temporal variation in sponge-dominated assemblages on exposed and sheltered temperate reefs. Mar. Ecol. Prog. Ser. Submitted manuscript. CHAPTER 4 - Patterns Associated with Anthropogenic Disturbance Roberts, D. E., Scanes, P. R. (2000). Spatial patterns in the macrobenthic assemblages inhabiting kelp {Ecklonia radiata) forests exposed to sewage effluent. Aust. J. Ecotox. 5: 89-102. Roberts, D. E., Smith, A., Ajani, P., Davis, A. R. (1998). Rapid changes in encrusting marine assemblages exposed to anthropogenic point-source pollution: a 'Beyond BACT approach. Mar. Ecol. Prog. Ser. 163: 213-224. Roberts, D. E. (1996). Patterns in subtidal marine assemblages associated with a deep-water sewage outfall. Mar. Freshwater Res. M: 1-9. Roberts, D. E. (1996). Effects of the North Head Deep-water sewage outfall on nearshore coastal reef macrobenthic assemblages. Mar. Poll. Bull. 33: 303-308. IX CHAPTER 5 - Processes Associated with the Effects of Sewage