Anthropogenic modification of estuaries: disturbance and artificial structures influence marine invasions By Katherine A. Dafforn B.Sc. (Hons) Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney, NSW 2052 Australia Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy within the University of New South Wales July 2009 COPYRIGHT STATEMENT ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed ……………………………………………........................... Date ……………………………………………........................... AUTHENTICITY STATEMENT ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Signed ……………………………………………........................... Date ……………………………………………........................... ii ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed …………………………………………….............. Date …………………………………………….............. iii THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Dafforn Fi rst na me: Ka theri ne Other name/s: Ann Abbreviation for degree as given in the University calendar: PhD School: Biological, Earth and Environmental Sciences Faculty: Science Ti tl e: Anthropogenic modification of estuaries: disturbance and artificial structures influence marine invasion Abstract 350 words maximum: Estuarine environments are threatened by the synergistic effects of anthropogenic disturbance and bioinvasion. The construction of artificial structures (such as pilings and pontoons) provides a habitat resource in close proximity to vessel hulls that may be carrying a wide range of non-indigenous fouling species. In addition, the release and accumulation of toxicants from antifouling (AF) paints on vessel hulls creates a chemical disturbance that may reduce the invasion resistance of native communities. This thesis examines how shipping- related disturbances affect sessile communities, and in particular what role AF paints and artificial structures play in the invasion of estuaries. Using a series of field-based experiments, I found that copper and tributyltin have the potential to influence both the transport of species to a new region, via the application of AF paints on vessel hulls, and their subsequent establishment, via the accumulation of AF biocides in estuaries. Temperature, pH, salinity and turbidity were also related to species distributions. During subtidal surveys of artificial and natural structures I found more non-indigenous species (NIS) on pilings and pontoons than on rocky reef, and shallow floating structures were identified as hotspots for invaders. These findings suggest that artificial structures play an important role in the initial establishment of sessile NIS in new regions. A restricted subset of NIS were also present on the reefs sampled during the survey and I conducted manipulative experiments to determine factors affecting the invasibility of turf and canopy-forming algal assemblages. The resident assemblage provided a barrier to most invaders, particularly when light and sedimentation levels were also high (i.e. on horizontal substrate). My results suggest that the areas of reef most susceptible to invasion are vertical rock walls and those subjected to frequent disturbances that release space. In summary, this is the first study to relate copper and tributyltin contamination in the field to NIS distributions. My research has also highlighted the potential role of artificial structures in facilitating the establishment of NIS in estuaries and identified invasion threats to rock wall communities and disturbed reefs in estuarine systems. Declaration relating to disposition of project thesis/dissertation I hereby gr ant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). …………………………………………………………… ……………………………………..……………… ……….……………………...…….… Signature Witness Date The University recogni ses that there may be exceptional circum stances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS iv Acknowledgements First and foremost, I would like to thank my supervisors Emma Johnston and Tim Glasby. We began this journey with my honours project and four years on they have never wavered in their support and guidance. Your ideas and enthusiasm have made a great combination and I could not have done it without you. Thank you. I am grateful to everyone in the Johnston/Poore labs, more recently the ‘Subtidal Ecology and Ecotoxicology Group’. It has been a pleasure and a privilege to work with such an amazing group of people. In particular, I’d like to thank Richard Piola for his mentorship during the early years. I’d also like to thank Kate Stuart, Bron Cumbo, Graeme Clark, Nicole Hill, Dave Roberts, Lou McKenzie, Alex Campbell, Chris Hellyer, Luke Hedge and Marty Hing for their help with fieldwork through sun, rain and improvisations (marine science would not be possible without cable ties!). A special thank you to my undergraduate helpers, Derrick Cruz, Laura Ryan and Mel Sun, you were a joy to work with and made fieldwork possible. I would also like to thank John Lewis for being the oracle of all things fouling and for providing paints. Thanks to the marinas for providing access as well as hot showers and tea to revive cold and tired research students; Steve Jeffress (Clontarf Marina), Kelvin Rabbitts (Cammeray Marina), Arthur King (Balmain SC), DPI Fisheries Gore Bay, Erin Honeman (Burraneer Bay Marina), Bob Grounds (Cronulla Marina), David Randall (Royal Prince Alfred Yacht Club), Brian Timbs (Pittwater Aquatic Club), Tony West (Quays Marina), Harry Standen (Dolans Bay Marina), and the port authorities; Port Kembla Port Authority and Newcastle Port Authority. Thanks to all for making these experiments possible. My love and thanks to my family, especially my mum who has been my most reliable and active fieldwork assistant (UVMBI) throughout my project. To my sister Jolene, her husband Izhar and little peanut (can’t wait to meet you), thank you for keeping me sane and well stocked with chocolates… Finally, to Cyrus, who probably knows my thesis as well as I do. Thanks for supporting me through the good and bad times and for staying with me through the final countdown. v Table of contents Appendices x List of Tables xi List of Figures xiii Abstract 1 Chapter 1. General introduction 3 Disturbance and invasion 5 Antifouling paints as agents of disturbance 6 Artificial structures as agents of disturbance 7 Invasibility of rocky reef 8 Thesis outline 9 Chapter 2. Links between estuarine condition and spatial distributions of marine invaders 11 Abstract 11 Introduction 12 Methods 16 Study sites 16 Biodiversity survey and experimental comparison of antifouling paints 17 Data analyses 20 Comparison of heavy metals and physico-chemical variables between estuaries 21 Results 23 Spatial variation in species distribution and diversity 26 Heavy