RIGS-TO-REEFS ECOLOGY: OFFSHORE OIL AND GAS PLATFORMS AS NOVEL ECOSYSTEMS SEAN VAN ELDEN BSC. HONS. The Wandoo B platform off the coast of Dampier, Western Australia. THIS THESIS IS PRESENTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF THE UNIVERSITY OF WESTERN AUSTRALIA SCHOOL OF BIOLOGICAL SCIENCES 2020 [BACK PAGE] Title image: Sean van Elden THESIS DECLARATION I, Sean van Elden, certify that: This thesis has been substantially accomplished during enrolment in this degree. This thesis does not contain material which has been submitted for the award of any other degree or diploma in my name, in any university or other tertiary institution. In the future, no part of this thesis will 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 Western Australia and where applicable, any partner institution responsible for the joint-award of this degree. This thesis does not contain any material previously published or written by another person, except where due reference has been made in the text and, where relevant, in the Authorship Declaration that follows. This thesis does not violate or infringe any copyright, trademark, patent, or other rights whatsoever of any person. The research involving animal data reported in this thesis was assessed and approved by The University of Western Australia Animal Ethics Committee. Approval #: RA/3/100/1484. The research involving animals reported in this thesis followed The University of Western Australia and national standards for the care and use of laboratory animals. The following approvals were obtained prior to commencing the relevant work described in this thesis: AU-COM2012-170, AU-COM2018-426, PA2018-00036-1, PA2018-00091-1, PA2018-00091-2, PA2018-00079, DPAW 01-000049-4, DPAW 01000049-7, DPAW 01-000049-8, CMR-17-000526, CMR-16-000426, CMR-18-000550, and Fisheries Exemption Numbers 2853 and 3172. This thesis contains published work and/or work prepared for publication, some of which has been co-authored. Signature: Date: 14 December 2020 i ABSTRACT There are thousands of oil and gas platforms (offshore platforms) situated offshore of coastlines around the world. Shortly after installation, these platforms become habitats for a variety of marine organisms, and over their ~30-40 year life spans, they can develop into highly complex artificial reefs. In many locations, these platforms also provide protection from fishing through the presence of exclusion zones, acting as de facto marine protected areas. When offshore platforms reach the end of their productive lives they are decommissioned, a process which, in most cases, involves complete removal of the platform from the marine environment. However, this process also results in the destruction of the long-established marine community. In some regions, Rigs-to-Reefs programs provide options for in situ decommissioning, ensuring that artificial reefs created by infrastructure are preserved. However, the ecology of many offshore platforms, particularly outside of major oil and gas (O&G) producing regions, is poorly understood. In Chapter 2, I reviewed the literature on the ecology of offshore platforms globally to determine whether restoration ecology principles, and specifically the novel ecosystem concept, is applicable to offshore platforms. I found that ecosystems created by offshore platforms are consistent with the concept of novel ecosystems, and therefore novel ecosystems management principles can be applied to offshore platforms. In this chapter I provide a method for recognising, classifying, and managing ecosystems created by offshore platforms, using existing decommissioning decision analysis models already implemented by industry stakeholders. The empirical components of my thesis are based on fieldwork at an active oil platform in northwest Australia and two natural “control” habitats within the region. Stereo baited remote underwater video systems (Stereo-BRUVS), both midwater and seabed, were used because they are a non-destructive and standardised method for documenting diversity, abundance and biomass of both demersal and pelagic species. In total, 1,125 BRUVS were deployed, recording 35,070 animals from 358 taxa. I used this dataset to assess the ecological role of offshore platforms, and demonstrated the usefulness of BRUVS for documenting rare species and behaviours. ii In Chapter 3, I assessed the Wandoo oil platform within the novel ecosystems framework. I compared the fish assemblages at Wandoo with two natural sites: one resembling the habitat found in the oilfield pre-installation, and the other being a natural reef. Both species assemblages, demersal and pelagic, and benthic habitat around the Wandoo platform more closely resemble a natural reef than the site preinstallation. This chapter demonstrates the ecological importance of the Wandoo platform within a region largely depauperate of hard substrate, and the role platforms play in increasing regional diversity and providing protection from destructive fishing activities. In Chapter 4, I document the first known wild observation of putative decapod mimicry by a cuttlefish Sepia cf. smithi. This cuttlefish was observed at the Wandoo platform, displaying ‘crustacean-like aggressive mimicry’ while approaching the stereo-BRUVS bait bag. Records such as this are important in understanding how animals behave in their natural environments, and show that stereo-BRUVS are an effective method of studying animal behaviour in situ. Industry-focused research enables us to expand our knowledge of the typically understudied ecosystems around offshore structures, and observe new behaviours and interactions. In Chapter 5 I documented the abundance of threatened elasmobranchs in Australia, including within the Wandoo field. Endangered elasmobranchs are highly vulnerable to fishing pressure and climate change, and knowledge of where they are found is critical to effectively manage their populations. Abundance of these species around Wandoo was among the highest across the nine regions studied. This finding is significant because Wandoo excludes fishing activity, acting as a refuge for these species in a region exposed to significant fishing pressure. The presence of offshore platforms can result in the emergence of novel ecosystems characterised by unique species assemblages and ecosystem services. The marine community around the Wandoo platform has shifted from its historical state to resemble a reef-type community, which meets the criteria of novel ecosystems. This platform also potentially acts as a refuge for threatened elasmobranchs in a region of high fishing pressure, further underlining the importance of recognising the ecological value of offshore platforms when making decommissioning decisions. The findings iii presented here will help to inform decommissioning of the Wandoo platform, and more generally Australia’s future decommissioning policies. iv ACKNOWLEDGEMENTS I would firstly like to thank Jessica Meeuwig for her endless patience and guidance as my supervisor. Jessica took a chance on me, finding a path for me to enrol as a PhD candidate where others had said it was impossible. Over the four years since our first meeting, Jessica has been a mentor and a friend. Through the trials and tribulations associated with both PhD candidature and life in general, she was there to offer encouragement, support, and a sense of perspective. I have watched and been inspired by Jessica’s tireless efforts to save the oceans and to encourage representation in science, no matter who stands in her way. I am eternally grateful for everything I have learned from her on this journey. Thank you to Jan Hemmi for his guidance and advice throughout my PhD. Jan always provided a fresh perspective during our discussions, and I was welcomed into his weekly lab meetings from the start. My thanks also to Richard Hobbs, whose work on novel ecosystems laid the foundation for the very concept of my dissertation. Richard was always available to offer guidance and thought-provoking discussion and helped me navigate the amalgamation of two contentious topics, oil platforms and novel ecosystems. My colleagues and friends in the Marine Futures Lab have been a constant source of support, motivation, entertainment and inspiration over the past four years. Tom Tothill was a key part of this journey in everything from fieldwork, to video analysis, to insightful conversations on offshore platform ecology. I am particularly grateful to everyone who joined me on the less than glamorous expeditions to Wandoo: David Tickler, Louis Masarei, Vyvyan Summers, Lincoln Hood, and Jack McElhinney. Thank you to the past and present members of the MFL family, particularly Chris Thompson, Adam Jolly, Nikki De Campe, Alex McLennan, Claire Raphael, Hanna Jabour Christ, Naima Andrea López, Jem Turner, Rachel White, Gabriel Vianna, Kristina Heidrich, James Hehre, and Shona Murray. Thank you to everyone at Vermilion Oil and Gas Australia (VOGA) that I have had the pleasure of working with over the past four years. Special thanks to Bruce Lake for being passionate about and supporting this project every step of the way. Thanks to v Abigail Anderson, Harry Cox and Glen Nicholson for not just joining the expeditions as reps, but actively engaging in every aspect of the (at times, exhausting) fieldwork. My fieldwork would not have been successful without the tireless and resourceful crew of the Jetwave Maddison, with particular thanks to Chris Helps, Dave Bond, Michael Gallop, and Gabby Morgan. On a personal note, I would like to thank my family for encouraging my love of the ocean for as long as I can remember. To my parents, Linda and Gerard, thank you for your unconditional love and support. You have done everything in your power to help me follow my passion and for that, I am eternally grateful. Thank you to the Lindeijer family for your support, particularly during a tough Honours year in a new city. You took me into your home and truly made me feel like part of the family. To my friends scattered across the globe who have been there for me along the way, thank you for your support. Finally, to my wife Nikki, thank you for being my best friend and biggest supporter over the last 13 years. From 4 am study sessions in Stellenbosch, to moving halfway around the world so that I could follow my passion, you have always been in my corner. Your unwavering belief in my potential, and your insistence on celebrating the small victories, have driven me to persevere through every challenge I have faced over the last four years. I am so grateful for everything you have done to help me get to this point – I truly could not have accomplished this without you. This project was made possible by the scientific foresight of VOGA, who realised the potential ecological value of Wandoo, and made this project possible through the VOGA PhD Scholarship in Rigs-to-Reefs Ecology. I would also like to acknowledge the UWA scholarship for international research fees, which I held during the course of my candidature. This research was supported by an Australian Government Research Training Program (RTP) Scholarship. vi Authorship Declaration - Co-Authored Publications This Dissertation is comprised of the following work that has been published or prepared for publication. Variation in presentation reflects journal requirements and editorial policies. Details of the work: van Elden S, Meeuwig JJ, Hobbs RJ, Hemmi JM. 2019. Offshore Oil and Gas Platforms as Novel Ecosystems: A Global Perspective. Frontiers in Marine Science 6: Article 548. Location in thesis: Chapter 2 Student contribution to work: I conceived the study with input from JJM and I wrote the first draft of the manuscript. I revised and submitted the manuscript with input from all co-authors. Co-author signatures and dates: Prof. Jessica Meeuwig A/Prof Jan Hemmi Prof. Richard Hobbs Date: 30/11/2020 Date: 30/11/2020 Date: 30/11/2020 Details of the work: van Elden S, Meeuwig JJ, Hobbs RJ. Can offshore platforms create novel ecosystems? A case study on the Wandoo field. Ecology and Evolution, in press. Location in thesis: Chapter 3 Student contribution to work: I developed the idea with input from JJM. I conducted all six field expeditions and processed around 75% of the imagery obtained during the expeditions, with the remainder processed by fellow lab members. I completed the data analysis and drafted the manuscript. I revised the manuscript with input from co-authors. Co-author signatures and dates: Prof. Jessica Meeuwig Prof. Richard Hobbs Date: 30/11/2020 Date: 30/11/2020 vii Details of the work: van Elden S, Meeuwig JJ. 2020. Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi). Marine Biodiversity 50:93. Location in thesis: Chapter 4 Student contribution to work: I observed the novel behaviour during image processing and developed the idea with input from JJM. I conducted all six field expeditions and processed around 75% of the imagery obtained during the expeditions, with the remainder processed by fellow lab members. I completed the data analysis and drafted the manuscript. I revised and submitted the manuscript with input from JJM. Co-author signatures and dates: Prof. Jessica Meeuwig Date: 30/11/2020 Details of the work: van Elden S, Meeuwig JJ. Elevated abundance of threatened elasmobranchs around an offshore oil platform in Australia. Conservation Biology, in prep. Location in thesis: Chapter 5 Student contribution to work: I conceived the study with input from JJM. I conducted all six expeditions at the Wandoo locations, and processed around 75% of the imagery obtained from these locations. The rest of the expeditions and associated image processing were completed by fellow lab members. I wrote the first draft, and revised and submitted the manuscript with input from JJM. Co-author signatures and dates: Prof. Jessica Meeuwig Date: 30/11/2020 viii Details of the work: van Elden, S., Tothill, T., and Meeuwig, J. J. (2020). Strategies for obtaining ecological data to enhance decommissioning assessments. APPEA J. 60, 559–562. Location in thesis: Appendix 1 Student contribution to work: I conceived this publication along with TT. The concept for the publication was developed further by all authors, and I wrote the first draft of the manuscript along with TT. The manuscript was revised and submitted with input from all authors. Co-author signatures and dates: Prof. Jessica Meeuwig Mr Thomas Tothill Date: 30/11/2020 Date: 30/11/2020 Student signature: Date: 11/12/2020 I, Professor Jessica Meeuwig, certify that the student’s statements regarding their contribution to each of the works listed above are correct. Coordinating supervisor signature: Date: 11/12/2020 ix STATEMENT OF CANDIDATE CONTRIBUTIONS This Dissertation contains a General Introduction (Chapter 1), four data chapters (Chapters 2-5) each of which is in the form of a manuscript that is about to be submitted (Chapters 3 and 5), or published (Chapters 2 and 4), and a General Discussion (Chapter 6). I developed the ideas and hypotheses that underpin this Dissertation with input from my supervisors, Prof. Jessica Meeuwig, A/Prof. Jan Hemmi, and Prof. Richard Hobbs. My supervisors revised the manuscripts with input from other colleagues who coauthored the specific chapters. Chapter 2 was conceived when I first started reading the literature on offshore platforms. I noticed that the novel ecosystems concept had not, at that stage in 2017, been mentioned at all in the literature on offshore platform ecology. I developed the concept for this chapter through discussions with Prof. Jessica Meeuwig and Prof. Richard Hobbs. I drafted the manuscript and all of my supervisors provided valuable input in revising and improving the manuscript. The data collected from the Wandoo field and adjacent natural habitats comprised the major field component of my dissertation, and involved six field expeditions over three years. I created the survey designs for these expeditions with input from Prof. Jessica Meeuwig. I conducted all expeditions with assistance from various members of the MFL. I conducted most of the image analysis, supported by the MFL due to the volume of imagery obtained during the expeditions. These data formed the basis of chapters 35 of this dissertation. The Wandoo expeditions were funded by Vermilion Oil and Gas Australia. The databases used to analyse the abundance of threatened species throughout tropical Australia (Chapter 5) were mainly generated by the Great West Ozzie Transect (GWOT). This sampling programme was conducted by the Marine Futures Lab (MFL) from the Kimberley in the north to the Recherche Archipelago in the south and commenced in 2013. The Marine Futures Lab databases used in Chapter 5 also contain data from previous surveys conducted by the MFL. These surveys were funded by a x combination of sources, including the Ian Potter Foundation, TeachGreen, Woodside Energy and the Clough Foundation. I conceived of the idea for the manuscript presented in Chapter 3, with input from Prof. Meeuwig. I conducted the analyses and wrote the first draft of the manuscript with input from Prof. Meeuwig. Prof. Meeuwig and Prof. Richard Hobbs provided input and revision of the manuscript. I developed the concepts for chapters 4 and 5 with input from Prof. Jessica Meeuwig. I conducted the analyses and drafted the manuscripts, with input from Prof. Meeuwig throughout. xi TABLE OF CONTENTS Contents Authorship Declaration - Co-Authored Publications ............................................................. vii List of Tables ....................................................................................................................... xv List of Figures .................................................................................................................... xvii Chapter 1 General Introduction ................................................................................................ 1 1.1 Offshore platforms ......................................................................................................... 1 Background ...................................................................................................................... 1 Decommissioning ............................................................................................................. 1 Rigs-to-Reefs .................................................................................................................... 2 Ecology of offshore platforms ........................................................................................... 4 1.2 Novel Ecosystems ........................................................................................................... 6 1.3 Methods for Studying Platform Fish Communities .......................................................... 8 1.4 Australia’s Northwest Shelf............................................................................................. 9 1.5 Aims of Research ...........................................................................................................12 1.6 Approach to thesis field studies and statistical analysis ..................................................14 Field studies ....................................................................................................................14 Statistical analysis............................................................................................................17 1.7 Additional Information ..................................................................................................18 1.8 Summary .......................................................................................................................19 1.8 References ....................................................................................................................20 Chapter 2 Offshore Oil and Gas Platforms as Novel Ecosystems: A Global Perspective .............31 2.1 Abstract .........................................................................................................................31 2.2 Introduction ..................................................................................................................32 2.3 Decommissioning ..........................................................................................................34 2.4 Rigs-To-Reefs.................................................................................................................35 2.5 Ecology of Offshore Platforms .......................................................................................37 2.6 Novel Ecosystems ..........................................................................................................39 2.7 Conclusion .....................................................................................................................44 2.8 Acknowledgements .......................................................................................................46 2.9 Statements ....................................................................................................................46 Author Contributions.......................................................................................................46 Funding ...........................................................................................................................46 Conflict of Interest Statement .........................................................................................46 2.10 References ..................................................................................................................46 xii Chapter 3 Offshore platforms as novel ecosystems: a case study from Australia’s Northwest Shelf........................................................................................................................................54 3.1 Abstract .........................................................................................................................54 3.2 Introduction ..................................................................................................................55 3.3 Materials and Methods .................................................................................................59 Study sites .......................................................................................................................59 Stereo-baited underwater video systems ........................................................................60 Data collection ................................................................................................................61 Data processing and treatment .......................................................................................62 Statistical analyses...........................................................................................................64 3.4 Results...........................................................................................................................66 Environment ...................................................................................................................66 Demersal richness, abundance, biomass and fork length .................................................68 Pelagic richness, abundance, biomass and fork length .....................................................68 Community assemblages .................................................................................................69 3.5 Discussion .....................................................................................................................79 Wandoo as a novel ecosystem .........................................................................................82 Implications for decommissioning ...................................................................................84 3.6 Statements ....................................................................................................................85 Data Accessibility:............................................................................................................85 Competing interests: .......................................................................................................86 Author contributions: ......................................................................................................86 Acknowledgements .........................................................................................................86 3.7 References ....................................................................................................................86 3.8 Appendices....................................................................................................................93 Chapter 4 Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi)...................................................................................................................................101 4.1 Abstract .......................................................................................................................101 4.2 Introduction ................................................................................................................102 4.3 Materials and methods ................................................................................................103 4.4 Results.........................................................................................................................104 4.5 Discussion ...................................................................................................................105 4.6 Acknowledgements .....................................................................................................109 4.7 Statements ..................................................................................................................109 Funding .........................................................................................................................109 Conflicts of interest/Competing interests ......................................................................109 Ethical Approval ............................................................................................................109 xiii Sampling and field studies: ............................................................................................109 Data Availability ............................................................................................................109 Authors' contributions ...................................................................................................109 4.8 References ..................................................................................................................110 Chapter 5 Elevated abundance of threatened elasmobranchs around an offshore oil field in Australia ...............................................................................................................................113 5.1 Abstract .......................................................................................................................113 5.2 Introduction ................................................................................................................114 5.3 Materials and Methods ...............................................................................................117 Video-based sampling of elasmobranchs .......................................................................117 Elasmobranch analyses..................................................................................................121 Environmental drivers ...................................................................................................123 5.4 Results.........................................................................................................................124 Comparing threatened elasmobranch abundance between regions...............................125 Differences in threatened elasmobranch community assemblages ................................127 Environmental and anthropogenic drivers .....................................................................129 5.5 Discussion ...................................................................................................................131 5.6 References ..................................................................................................................135 5.7 Supplementary information.........................................................................................143 Chapter 6 General Discussion ................................................................................................156 6.1 Synergy amongst chapters ...........................................................................................157 Offshore platforms as novel ecosystems ........................................................................158 Ecology of the Wandoo field ..........................................................................................159 The use of stereo-BRUVS to study offshore platform-associated communities...............161 6.2 Caveats and future directions ......................................................................................162 6.3 Implications for Decommissioning ...............................................................................164 6.4 Conclusion ...................................................................................................................165 6.5 References ..................................................................................................................166 Appendix 1 Strategies for obtaining ecological data to enhance decommissioning assessments .............................................................................................................................................170 A1.1 Abstract ....................................................................................................................170 A1.2 Introduction ..............................................................................................................170 A1.3 Acknowledgements ...................................................................................................175 A1.4 Conflict of interest.....................................................................................................175 A1.5 References ................................................................................................................175 Appendix 2: Summary of Expeditions ....................................................................................177 Appendix 3: Identification of potential species pool ..............................................................180 xiv LIST OF TABLES Table 2.1 Examples from the literature of practical considerations preventing offshore platform sites from being returned to their historical state. ....................................................44 Table 3.1 Pairwise PERMANOVA tests comparing demersal and pelagic variation between sites for each survey, for taxonomic richness (TR), log total abundance (log 10TA), log total biomass (log10TB) and log fork length (log10FL). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. ...........................................................................................................................73 Table 3.2 Pairwise PERMANOVA results comparing abundance and biomass of the pelagic and demersal taxonomic assemblages between sites: Wandoo (WN); Control Sand (CS); and Control Reef (CR). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. .................74 Table 3.3 Abundance, biomass and prevalence of taxa observed at a single site at WN (16 demersal and 1 pelagic species), CR (5 demersal and 0 pelagic species) and CS (4 demersal and 0 pelagic species), based on demersal and pelagic sampling records. Species marked with an asterisk are commonly caught commercially and/or recreationally in the North Coast Bioregion (Rome and Newman, 2010). ....................................................................................................77 Table 4.1 Record of all cuttlefish seen on BRUVS deployments with information on habitat, depth, sea surface temperature (SST), estimated visibility (vis) and activity for each of the three sites: A reef comprising rocky substrate and various sessile invertebrates .............................104 Table 4.2 Cuttlefish species found in the study region with information on maximum length (TL; cm), mantle length at maturity (ML; cm), depth range (m), habitat association and diel activity where available. Taxon authorities are provided for species not previously mentioned in this manuscript. Derived from SeaLifeBase (Palomares and Pauly, 2019), Atlas of Living Australia (www.ala.org.au, 2020) and Cephbase (www.cephbase.eol.org, 2020). ..................108 Table 5.1 Wilcoxon Signed Rank tests comparing mean abundance of demersal and pelagic threatened elasmobranchs at the three Wandoo locations with the means of the other tropical regions. Tests were conducted for Vulnerable (VU), Endangered (EN) and Critically Endangered (CR) taxa, as well as all of these taxa combined (Total). P-values in bold and marked with an asterisk are < 0.05. ................................................................................................................127 Table 5.2 Distance-based linear model (DistLM) results based on the most parsimonious model predicting abundance of demersal and pelagic threatened elasmobranchs. Variables included are: depth (m); dissolved oxygen (O2; mmol/L); sea surface temperature (SST; °C); travel time to market (TT_Market; mins) distance to port (DistPort; km); Chlorophyll concentration (Chl-a; mg/m3). The degrees of freedom (d.f.) are reported in parentheses after the Pseudo-F value. proportion of variation in abundance explained by each variable (Prop.) and cumulative proportion of variation explained by the variables (Cumul. Prop.) are also included. .............129 Table A2.1 Summary of all expeditions in which seabed stereo-BRUVS were deployed. The table includes number of days over which the expedition occurred (Days), latitude (LAT) and longitude (LONG) of the locations in decimal degrees, and the number of seabed stereo-BRUVS deployed (n)..........................................................................................................................177 Table A2.2 Summary of all expeditions in which mid-water stereo-BRUVS were deployed. The table includes number of days over which the expedition occurred (Days), latitude (LAT) and longitude (LONG) of the locations in decimal degrees, and the number of mid-water stereoBRUVS deployed (n). .............................................................................................................178 xv Table A3.1 Potential species pool of tropical Australian threatened elasmobranchs, derived from Fishbase and Atlas of Living Australia (Froese and Pauly, 2019; www.ala.org.au, 2020). The IUCN Red List classification (IUCN) of each species is included (IUCN, 2020). Taxa identifications are in bold. For each family, identifications to genus are listed with all possible species in that genus. Identifications to family are listed thereafter, followed by any possible species in that family not already listed. ................................................................................180 Table A3.2 Potential species identifications for those taxa identified to family or genus, separated by family. Species records for the area surrounding Wandoo and the two control sites are derived from Fishbase, Sealifebase and Atlas of Living Australia (Froese and Pauly, 2019; Palomares and Pauly, 2019; www.ala.org.au, 2020). Taxa identifications are in bold. For each family, identifications to genus are listed with all possible species in that genus. Identifications to family are listed thereafter, followed by any possible species in that family not already listed. .................................................................................................................181 SUPPLEMENTARY AND APPENDIX TABLES Appendix 3.1 Environmental data for each survey used in the DistLM analyses, including start and end dates, depth, sea surface temperature (SST), and chlorophyll concentration (Chl-a). Data were derived from: Geoscience Australia 250 m bathymetry (Whiteway, 2009) and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020). The sites are: Wandoo (WN); Control Reef (CR); and Control Sand (CS)……………………………………………………….93 Appendix 3.2 Pairwise PERMANOVA comparing demersal variation between years for autumn and spring at each site for taxonomic richness (TR), log total abundance (log10TA), log total biomass (log10TB) and log fork length (log10FL). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses…………………94 Appendix 3.3 Pairwise permanova comparing pelagic variation between years for autumn and spring at each site, in terms of taxonomic richness (TR), log total abundance (log 10TA), log total biomass (log10TB) and log fork length (log10FL. Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses………………………………95 Appendix 3.4 Prevalence (%) of demersal species recorded at WN, CR and CS. Prevalence refers to the number of deployments on which a taxon was observed, out of the total number of deployments at that site.……………………………………………………………………………………………………………………………………………………….96 Appendix 3.5 Prevalence (%) of pelagic species recorded at WN, CR and CS. Prevalence refers to the number of deployments on which a taxon was observed, out of the total number of deployments at that site………………………………………………………………………………………………………………………………………………….…….99 Supplementary Table 5.1 Demersal regions and locations, including average coordinates for each location (decimal degrees), years in which the locations were surveyed, and number of surveys per location. Bolded text indicates the regions, with the locations listed below each region. ..................................................................................................................................144 Supplementary Table 5.2 Pelagic regions and locations, including average coordinates for each location, years in which the locations were surveyed, and number of surveys per location. Bolded text indicates the regions, with the locations listed below each region. .....................145 Supplementary Table 5.3 Environmental and anthropogenic variables for locations sampled with seabed stereo-BRUVS. Variables include: distance to port (DistPort); distance to coast (DistCoast); dissolved oxygen (O2); salinity (Sal); sea surface temperature (SST); and depth. Bolded text indicates the regions, with the locations listed below each region. Distance to market and population were computed using the LandScan 2016 database (Dobson et al., 2000), while distances to marine features were computed using bathymetry data (Yesson et al., 2020). Environmental data were derived from: Geoscience Australia (GA) 250 m xvi bathymetry (Whiteway, 2009); GA Australian submarine canyons (Huang et al., 2014); CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020) ....................................................................................................................................146 Supplementary Table 5.4 Environmental and anthropogenic variables for locations sampled with midwater stereo-BRUVS. Variables include: linear distance to cities (LinDistCities); travel time to market (TravelTime_market); time to nearest population (TravelTime_pop); linear distance to nearest population (LinDistPop); distance to port (DistPort); distance to seamounts (DistSeamounts); distance to coral reef (DistCoralReef); depth; slope; distance to coast (DistCoast); chlorophyll concentration (Chl); and sea surface temperature (SST). Bolded text indicates the regions, with the locations listed below each region. Distance to market and population were computed using the LandScan 2016 database (Dobson et al., 2000), while distances to marine features were computed using bathymetry data (Yesson et al., 2020). Environmental data were derived from: Geoscience Australia (GA) 250 m bathymetry (Whiteway, 2009); GA Australian submarine canyons (Huang et al., 2014); CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020) ......147 Supplementary Table 5.5 List of threatened elasmobranchs recorded on seabed stereo-BRUVS by location, including their IUCN Red List classifications (IUCN): Vulnerable (VU); Endangered (EN) and Critically Endangered (CR). The regions are Northeast (NE), Cocos-Keeling Islands (CI), Northwest (NW), Wandoo (WN), Central North (CN) and Central South (CS). Bolded text indicates the regions, with the locations listed below each region. ........................................150 Supplementary Table 5.6 List of threatened elasmobranchs recorded on midwater stereoBRUVS by location, including their IUCN Red List classification (IUCN)s: Vulnerable (VU); Endangered (EN) and Critically Endangered (CR). The regions are Northeast (NE), Cocos (Keeling) Islands (CI), Northwest (NW), Wandoo (WN), Central North (CN) and Central South (CS). Bolded text indicates the regions, with the locations listed below each region. .............153 LIST OF FIGURES Figure 1.1 Potential options for the decommissioning of offshore platforms, including complete removal, various reefing options, and alternative uses of the existing infrastructure. Figure from Sommer et al. (2019). ............................................................................................ 3 Figure 1.2 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale. ...................................................................15 Figure 3.1 Location of the three study sites, Wandoo, Control Reef and Control Sand, approximately 75 km north-west of Dampier, Western Australia ............................................60 Figure 3.2 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale ....................................................................61 Figure 3.3 Percentage habitat composition for each of the three sites. The habitat types are sand (yellow), sparse macrobenthos (light green) and dense macrobenthos (dark green). ......67 Figure 3.4 Mean values with standard errors (SE) for taxonomic richness (TR), and logged values of total abundance (TA), total biomass (TB) fork length (FL) by survey for demersal (left) xvii and pelagic (right) communities at the three sites: Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). ..................................................................................................72 Figure 3.5 Canonical analysis of principal coordinates (CAP) for abundance of (a) demersal and (b) pelagic taxonomic assemblages at Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). Species clockwise from top in (a) are: bluespotted emperor Lethrinus punctulatus, northwest blowfish Lagocephalus sceleratus, brushtooth lizardfish Saurida undosquamis, galloper Symphorus nematophorus, spot-cheek emperor Lethrinus rubrioperculatus, bluespotted tuskfish Choerodon cauteroma, and turrum Carangoides fulvoguttatus. Taxa clockwise from top in (b) are: live sharksucker Echeneis naucrates, scads Decapterus sp., silky shark Carcharhinus falciformis, herrings Clupeidae sp., great barracuda Sphyraena barracuda, and rainbow runner Elegatis bipinnulata. .............................................75 Figure 3.6 Canonical analysis of principal coordinates (CAP) for biomass of (a) demersal and (b) pelagic taxonomic assemblages at Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). Species clockwise from top in (a) are: bluespotted emperor Lethrinus punctulatus, milk shark Rhizoprionodon acutus, brushtooth lizardfish Saurida undosquamis, galloper Symphorus nematophorus, spot-cheek emperor Lethrinus rubrioperculatus, bluespotted tuskfish Choerodon cauteroma, turrum Carangoides fulvoguttatus, and areolate grouper Epinephelus areolatus. Taxa clockwise from top in (b) are: great hammerhead Sphyrna mokarran, live sharksucker Echeneis naucrates, cobia Rachycentron canadum, silky shark Carcharhinus falciformis, rainbow runner Elegatis bipinnulata, and great barracuda Sphyraena barracuda. Images © R. Swainston/anima.fish 76 Figure 4.2 Selected frames from the video image (Online Resource 1): Sepia sp. approaches the bait bag while mimicking decapod (a), extends its arms while investigating the bait bag (b), before moving away from the camera mimicking decapod locomotion (c). ...........................106 Figure 5.1 Location of the study regions around Australia: Cocos-Keeling Islands (pink; to the northwest of the Australian mainland); Northeast (red); Northwest (orange); Wandoo (yellow) Central North (dark green); and Central South (light green)...................................................120 Figure 5.2 Location of the Wandoo Platform and the two nearby natural locations, Wandoo Reef and Wandoo Sand, approximately 75 km north-west of Dampier, Western Australia ....121 Figure 5.3 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale. .................................................................122 Figure 5.4 Demersal (a) and pelagic (b) abundance of threatened elasmobranchs by region: Northeast (NE); Cocos-Keeling Islands (CI); Northwest (NW); Wandoo Platform (WP); Wandoo Sand (WS); Wandoo Reef (WR); Central North (CN); and Central South (CS). Classifications depicted are Vulnerable (yellow); Endangered (Orange) and Critically Endangered (Red). Patterned bars indicate the Wandoo locations. .....................................................................128 Figure 5.5 Canonical analysis of principal coordinates (CAP) for abundance of (a) demersal and (b) pelagic taxonomic assemblages. Locations shown are: Northeast (Red); Northwest (Orange); Wandoo Platform (yellow triangle); Wandoo Reef (yellow diamond); Wandoo Sand (yellow square); Central North (dark green); and Central South (light green). Taxa clockwise from top in (a) are: bentfin devilray Mobula thurstoni; wedgefish Rhychobatus sp.; requiem shark Carcharhinus sp.; silky shark Carcharhinus falciformis; leopard shark Stegostoma tigrinum; and tawny nurse shark Nebrius ferrugineus. Taxa clockwise from top in (b) are: oceanic whitetip Carcharhinus longimanus; dusky shark Carcharhinus obscurus; sandbar shark Carcharhinus plumbeus; requiem shark; mobula ray Mobula sp.; great hammerhead Sphyrna xviii mokarran; and silvertip shark Carcharhinus albimarginatus. Images © R. Swainston/anima.fish .............................................................................................................................................130 Figure A1.1 Stereo-BRUVS sampling sectors in the Wandoo Field..........................................173 SUPPLEMENTARY FIGURES Supplementary Figure 5.1 Schematics of (a) seabed and (b) mid-water stereo-BRUVS. .........143 xix Ch 1: General Introduction CHAPTER 1 GENERAL INTRODUCTION 1.1 OFFSHORE PLATFORMS Background Oil and natural gas together account for 60% of the fuel consumed worldwide (British Petroleum P.L.C., 2020). Offshore oil and gas (O&G) fields contribute a significant portion of global energy production, with 30% of oil and 27% of gas produced offshore (Planète Énergies, 2015; US Energy Information Administration, 2016). Offshore energy production began in the Gulf of Mexico in the 1940s: Ship Shoal Block 32, a converted World War II navy barge, was installed in waters off the Louisiana coast in 1947, becoming the first platform to be installed out of sight of land (Aagard and Besse, 1973; Beu, 1988). This milestone led to 70 years of technological and engineering advances, with modern-day platforms weighing hundreds of thousands of tonnes, and able to withstand severe environmental conditions including tropical cyclones (Dragani and Kotenev, 2013; Elsayed et al., 2016; Sheng and Hong, 2020). The world’s deepest platform, Perdido, is installed in waters 2,450 m deep in the Gulf of Mexico, underlining how far offshore production has progressed in a relatively short period (Lohr and Smith, 2010). There are currently over 12,000 offshore O&G installations in the continental shelf waters of 53 countries, varying greatly in size and water depth (Ars and Rios, 2017; Parente et al., 2006). These installations can be broadly divided into two groups: platforms, which are permanently fixed to the seabed; and rigs, which are moveable platforms that are temporarily secured at a location. Decommissioning The end of life process for offshore O&G platforms (hereafter offshore platforms) is referred to as decommissioning. Offshore platforms generally reach the end of their productive lives when extraction is no longer profitable, even though the platform itself may still be fit-for-purpose. Most oil fields have a production life of around 15-30 years, while deeper fields may have lifespans of less than ten years due to higher extractive costs (Planète Énergies, 2015). Decommissioning is a regulated process which involves shutting down production, plugging wells, and cleaning, capping, and possibly removing subsea pipelines and the platform itself (Hakam and Thornton, 1 Ch 1: General Introduction 2000). Decommissioning regulations vary greatly between regions: countries and regions such as the Australia and the North Sea prescribe complete removal of offshore platforms (Chandler et al., 2017; Ounanian et al., 2019). In contrast, the Gulf of Mexico, California, Brunei, and Malaysia all allow for in situ decommissioning options (Fowler et al., 2015; Pietri et al., 2011; Reggio Jr., 1987). The various regulations and decommissioning processes around the world were comprehensively assessed in two recent reviews (Bull and Love, 2019; Sommer et al., 2019). Decommissioning of offshore platforms typically occurs under one of five scenarios: (1) complete removal, whereby the entire platform structure is removed for onshore disposal (Fig. 1.1); (2) leave in place, which involves removing the superstructure and placing navigational aids on the above-surface shaft or jacket structure; (3) topping, where the structure is cut below the waterline and the top portion is either removed or placed next to the remaining structure; (4) horizontal reefing, which involves cutting the platform at the seabed and laying the structure horizontally; and (5) tow-andplace, where the platform is removed from the seabed and “reefed” at another location (Dauterive, 2000; Sommer et al., 2019). Other suggested alternatives include converting the existing platform for use as hotels, wind/wave power generators; mariculture farms, or research stations (Schroeder and Love, 2004; Sommer et al., 2019; Zawawi et al., 2012). Decommissioning is regulated under international law, specifically the 1996 Protocol to the London Dumping Convention, which prohibits the dumping, abandonment, or toppling of offshore platforms for the sole purpose of disposal (Elizabeth, 1996). However, in situ decommissioning is not specifically prohibited by this Protocol, which states that dumping does not include placement of the platform for purposes other than disposal (Elizabeth, 1996; Techera and Chandler, 2015). This ‘exception’ to the London Protocol allows countries to implement decommissioning policies allowing for alternatives to complete removal. Rigs-to-Reefs The primary reason for decommissioning offshore platforms in situ is for their use as designated artificial reefs, under programs typical referred to as “Rigs-to-Reefs” (RTR). The first structure to be “reefed”, prior to an official RTR program, was in 1979 when a 2 Ch 1: General Introduction 2,000 tonne subsea production system was towed from Louisiana to Florida to create an artificial reef (Kaiser, 2006). RTR was soon signed into federal law under the 1984 National Fishing Enhancement Act, with the primary intention of improving offshore fishing in the Gulf of Mexico (Reggio Jr., 1987). Over 500 platforms have since been reefed under state RTR programs in the Gulf of Mexico, which is a relatively small portion, around 11%, of the total number of platforms that have been installed in the region (Bull and Love, 2019). Brunei was not far behind the US in terms of RTR, establishing its own program in 1988 (Bull and Love, 2019). To date seven platforms Figure 1.1 Potential options for the decommissioning of offshore platforms, including complete removal, various reefing options, and alternative uses of the existing infrastructure. Figure from Sommer et al. (2019). have been reefed in Brunei, however with around 150 platforms having been installed at least 20 years ago in this region, there is scope for significant expansion of the Brunei RTR program (Bull and Love, 2019; Lyons et al., 2015). Malaysia also has many potential RTR candidates: there are hundreds of platforms in this region, around half of which are older than 25 years (Zawawi et al., 2012). However, as of 2015, the only offshore platform to be reefed in Malaysia was the Baram-8 platform, which collapsed in a storm in 1975 before being salvaged and reefed in a different location in 2004 (Lyons et al., 2015). Southeast Asia as a region may benefit from RTR programs, with 1,800 platforms of which almost half have been in place for over 20 years (Ars and Rios, 2017). Many Southeast Asian countries already have established artificial reef 3 Ch 1: General Introduction programs to enhance fisheries and tourism, and the shortage of decommissioning yards in the region would make onshore disposal difficult (Lyons et al., 2015). The North Sea and California are both regions where RTR programs have been discussed, or even legislated, but not implemented. In the North Sea, Greenpeace’s protest over the offshore disposal of the Brent Spar in 1995 effectively excluded RTR from the region (Jørgensen, 2012). The legacy of the Brent Spar has shaped RTR policy not just in the North Sea, but in other regions around the world (Lyons et al., 2015; Salcido, 2005; Zawawi et al., 2012). In California, RTR was legislated in 2010, after three previous unsuccessful attempts (Bull and Love, 2019; Pietri et al., 2011; Schroeder and Love, 2004). There was considerable division among stakeholders over the impacts of RTR in California, and no platforms have yet been reefed in the region (Manago and Williamson, 1997; Ounanian et al., 2019). Scientific research played a key role in the successful legislation of the California RTR program (Macreadie et al., 2012; Pietri et al., 2011), and Australia is taking a similar approach to its decommissioning policy. In Australia, offshore platforms must be completely removed at the time of decommissioning, despite scientific evidence of the environmental benefits of RTR (Techera and Chandler, 2015). However, Australia’s position has recently come under review, and this review process is to be based on independent scientific research, through the National Decommissioning Research Initiative (NDRI), as well as ongoing decommissioning research projects (Offshore Resources Branch, 2018). Ecology of offshore platforms Offshore platforms have been converted into artificial reefs for decades, and these structures also function as artificial reefs during their productive lives (Shinn, 1974). When a platform is installed, it provides bare, hard substrate that is available for colonisation by sessile organisms including sponges, corals, mussels and hydroids (Forteath et al., 1982; Todd et al., 2020b). The new habitat provided by offshore platforms can be transformed into complex reef-type habitat within a few years, and supports a range of marine fauna including invertebrates, fish, and marine megafauna (Driessen, 1986b; Love et al., 2003; McLean et al., 2017; Todd et al., 2016). Offshore platforms are some of the most productive marine habitats globally, with higher 4 Ch 1: General Introduction biomass and secondary production than some pristine Pacific coral reefs (Claisse et al., 2014; Friedlander et al., 2014). Similarly to pristine reefs, much of the biomass around platforms is made up of top predators such as groupers, jacks and sharks, as described in Gabon (Friedlander et al., 2014), as well as marine mammals (Clausen et al., 2021; Todd et al., 2009). Offshore platforms are physically complex structures and create habitat from the seafloor to the surface. High habitat complexity is associated with higher abundance and diversity of fishes through the provision of refuge opportunity and reduced predation pressure (Claisse et al., 2014; Lingo and Szedlmayer, 2006). Habitat complexity also influences reproduction and recruitment, with some juvenile fishes preferentially selecting more complex habitat (Sayer et al., 2005; Todd et al., 2018). Artificial reefs, including offshore platforms, create an “ecological halo” of elevated abundance and diversity in the area surrounding the structure, to a distance of around 15-34 m (Reeds et al., 2018; Scarcella et al., 2011; Stanley and Wilson, 1996). In California, offshore platforms have been found to support large populations of Critically Endangered bocaccio rockfish Sebastes paucispinis (IUCN, 2020): populations at eight offshore platforms support an estimated 430,000 juvenile bocaccio (Love et al., 2006). Juvenile recruitment was also higher at platforms than in natural habitats (Love et al., 2006). In the Gulf of Mexico, 246 fish species have been recorded at offshore platforms (Cowan Jr. and Rose, 2016). The great barracuda Sphyraena barracuda was not known as a sport fishing species in Louisiana prior to the presence of offshore platforms (Dugas et al., 1979). In northwest Australia, Fowler and Booth (2012) found that artificial structures could support full populations of the red-belted anthias Pseudanthias rubrizonatus, from newly recruited juveniles to mature adults. Offshore infrastructure in northwest Australia supports a diverse range of both pelagic and reef-dependent species, and plays a particular important role for commercial fish species such as goldband snapper Pristipomoides multidens, saddletail snapper Lutjanus malabaricus, and mangrove jack Lutjanus argentimaculatus (Bond et al., 2018b; Pradella et al., 2014). 5 Ch 1: General Introduction Offshore platforms generally exclude fishing activity, particularly commercial fishing. This exclusion can either be through legislation, as is the case in Australia and Ghana, or through the presence of infrastructure acting as physical obstacles to longlining and seabed trawling (Chalfin, 2018; Commonwealth of Australia, 2010; de Groot, 1982; Fabi et al., 2004; McLean et al., 2019). The exclusion of fishing effectively means that offshore platforms and the waters surrounding them function as de facto marine protected areas (MPAs), providing a refuge from fishing and potentially helping to rebuild populations of overfished species (Friedlander et al., 2014; Fujii and Jamieson, 2016; Love et al., 2006). Offshore platforms may play important roles for marine megafauna. Platforms have been shown to act as fish aggregating devices (FADs), attracting small pelagic fishes and providing enhanced foraging opportunity for large predators, including transient species that may not be resident at the platforms (Franks, 2000; Scarcella et al., 2011). Large predators including bull sharks Carcharhinus leucas, tiger sharks Galeocerdo cuvier, great hammerheads Sphyrna mokarran, and porbeagles Lamna nasus have all been reported around offshore platform various regions, while white sharks Carcharodon carcharias have been reported near platforms in the Adriatic Sea (De Maddalena, 2000; Franks, 2000; Haugen and Papastamatiou, 2019; Reynolds et al., 2018). Other large marine megafauna observed at offshore platforms include whale sharks Rhincodon typus, basking sharks Cetorhinus maximus, oceanic manta rays Mobula birostris, minke whales Balaenoptera acutorostrata, and various seal and porpoise species (Bernstein et al., 2010; McLean et al., 2019; Robinson et al., 2013; Todd et al., 2009, 2016, 2020a). 1.2 NOVEL ECOSYSTEMS A novel ecosystem is one which has been altered by human activity and where restoration is not feasible or would result in the loss of ecosystem value (Hobbs et al., 2013a). The term “novel ecosystem” was introduced in 1997 (Chapin and Starfield, 1997), but the most comprehensive definition of the concept was developed by Hobbs et al. (2013) (Box 1). Novel ecosystems can emerge through both direct and indirect human activity, including species introductions, land-use changes, and climate change 6 Ch 1: General Introduction (Kennedy et al., 2013). A key assertion about novel ecosystems is that ecosystems BOX 1: NOVEL ECOSYSTEMS DEFINITION that have been altered are not necessarily (Hobbs et al., 2013a) ‘degraded’, but may just provide different ecosystem services from what was present “A NOVEL ECOSYSTEM IS A SYSTEM OF before (Hobbs, 2016). A frequently used ABIOTIC, BIOTIC AND SOCIAL COMPONENTS example of a novel ecosystem is the Mt THAT, BY VIRTUE OF HUMAN INFLUENCE, Sutro forest in San Francisco (Venton, 2013). DIFFER FROM THOSE THAT PREVAILED The native vegetation in this area has been HISTORICALLY, HAVING A TENDENCY TO SELF- almost entirely replaced by non-native ORGANIZE AND MANIFEST NOVEL QUALITIES species, predominantly Australian WITHOUT INTENSIVE HUMAN eucalyptus, creating a cloud forest. Due to the perceived fire risk posed by eucalyptus, it was proposed that the ecosystem be restored through the removal of the eucalyptus and planting of native vegetation. However, the cloud forest is argued to be less prone to fire due to its MANAGEMENT. NOVEL ECOSYSTEMS ARE DISTINGUISHED FROM HYBRID ECOSYSTEMS BY PRACTICAL LIMITATIONS (A COMBINATION OF ECOLOGICAL, ENVIRONMENTAL AND SOCIAL THRESHOLDS) ON THE RECOVERY OF HISTORICAL QUALITIES.” fog-trapping qualities. Furthermore, the Mt Sutro forest is the largest urban forest in San Francisco and is highly valued by the community for recreation, with significant public campaigns to save the forest (Venton, 2013). These factors represent important environmental and social considerations preventing this novel ecosystem from being restored to its historical state. There have been a handful of studies applying the novel ecosystem concept to marine ecosystems, including regime shifts on coral reefs and altering fish assemblages due to warming oceans (Graham et al., 2014; Harborne and Mumby, 2011). Various anthropogenic impacts in the oceans facilitate the emergence of novel ecosystems. Climate change-related impacts include ocean acidification, changes in temperature and oxygen content, and altered ocean circulation (Doney et al., 2012). These broadscale impacts drive novelty in marine systems concurrently with regional impacts, “A 7 Ch 1: General Introduction including illegal, unreported and unregulated (IUU) fishing, aquaculture, point source pollution, and coastal engineering (Perring and Ellis, 2013). Offshore platforms appear to be ideal candidates for the application of the novel ecosystem concept to marine systems, with ecosystem-level shifts occurring through what is effectively the creation of large artificial reefs. However, the novel ecosystem concept has only recently begun to gain traction in the field of offshore platform ecology. Schläppy and Hobbs (2019) developed a framework for classifying altered marine ecosystems, including offshore platforms, as novel, hybrid, or designed ecosystems. Sommer et al. (2019) suggested that the ecosystem-level shifts that occur due to the presence of offshore platforms present qualities consistent with the novel ecosystem concept. However, there has not yet been a quantitative assessment of an offshore platform within the framework of novel ecosystems. 1.3 METHODS FOR STUDYING PLATFORM FISH COMMUNITIES Offshore platforms present unique challenges for ecological sampling. Many platforms are located in waters too deep to be effectively surveyed by self-contained underwater breathing apparatus (SCUBA) divers, and access to the waters surrounding platforms is restricted in some regions. Many offshore platforms are also located significant distances from land, or in areas prone to adverse environmental conditions. A suite of sampling methods has been used to study the marine communities associated with offshore platforms. SCUBA diver observations of fish distribution on offshore platforms occurred as far back as the 1970s and underwater visual census (UVC) surveys have been conducted by divers on platforms around the world, including Brunei, the Gulf of Mexico, and California (Bull and Kendall, 1994; Chou et al., 1992; Meyer-Gutbrod et al., 2019; Shinn, 1974). A major disadvantage of this method is that the presence of divers can influence the species composition and density of fishes (Bohnsack and Bannerot, 1986; Sale and Douglas, 1981). Divers are also limited in the depth at which they can operate, and in many cases can only survey shallower sections of a platform. These constraints can be overcome through combining diver surveys with remotely operated vehicle (ROV) or submersible surveys of the deeper areas (Love et al., 1994). Manned submersibles allow for visual observations at significantly deeper depths than SCUBA 8 Ch 1: General Introduction divers, and have been used in the Gulf of Mexico (Shinn and Wicklund, 1989), as well as in a seven-year long survey in California (Love et al., 2019b). Fish catch data have been used to sample offshore platform-associated communities, either experimentally in the form of trammel net traps and longline surveys (Ajemian et al., 2015; Fabi et al., 2004; Scarcella et al., 2011), or using data from local fishing activity (Fujii, 2015). Fishing is also a component of tagging studies, with both acoustic telemetry and markrecapture tagging used at offshore platforms (Everett et al., 2020; Jørgensen et al., 2002; Love et al., 1994). Hydroacoustic surveys have been used to quantify fish abundance in the North Sea and the Gulf of Mexico, while ROVs have been used both in targeted surveys, and the use of industry ROV archives (McLean et al., 2017, 2019; Soldal et al., 2002; Stanley and Wilson, 2000; Todd et al., 2018). Platform-based observations of marine megafauna have been documented both in the form of opportunistic sightings (Haugen and Papastamatiou, 2019; Robinson et al., 2013) and designed monitoring programs (Todd et al., 2016). Baited remote underwater video systems (BRUVS) have been used more recently in a handful of studies on offshore infrastructure, in order to survey communities at various depths in the water column as well as on the seabed (Barker and Cowan Jr., 2018; Bond et al., 2018b; Schramm et al., 2020). Stereo-BRUVS are a well-established method for non-destructively sampling marine communities (Cappo et al., 2006) that can be used to sample both the seabed and the water column, (Letessier et al., 2013b; Whitmarsh et al., 2017). Stereo-BRUVS are cost-effective, can be deployed across large spatial scales, and are used to study abundance, biomass, diversity and distribution of marine fauna (Cappo et al., 2006; Letessier et al., 2015b). Stereo-BRUVS are also useful for studying less abundant animals such as migratory or endangered species (Letessier et al., 2015a; Thompson et al., 2019), and have recorded a suite of unique animal behaviours (Barley et al., 2016; Birt et al., 2019). 1.4 AUSTRALIA’S NORTHWEST SHELF Australia’s tropical marine region is vast, ranging across over 50 degrees of longitude from the Cocos-Keeling Islands remote territory in the west to the Great Barrier Reef in the East. This region encompasses diverse ecosystems, including seagrass beds, 9 Ch 1: General Introduction mangroves, coral reefs, seamounts, and estuaries (Lough, 2008). These ecosystems are used for a range of activities, including commercial and recreational fishing, O&G exploration and production, aquaculture, tourism, and recreation. Many of these ecosystems are only are partially protected from extractive activities under multipleuse MPAs, with the notable tropical MPAs being Ningaloo Marine Park, Great Kimberley Marine Park, and Great Barrier Reef Marine Park (Department of Parks and Wildlife, 2020; Parks Australia, 2020). This dissertation focuses on the Northwest Shelf (NWS) region along Australia’s tropical northwest coast. The NWS spans almost 2,500 km, from North West Cape in the south to Melville Island in the north, and is rich in natural resources (Wilson, 2013). This geographic province is comprised of four major sedimentary basins, from north to south: Bonaparte, Browse, Offshore Canning, and Carnarvon (Purcell and Purcell, 1988). The NWS has estimated oil reserves of 2.6 billion barrels (413 million cubic metres), but the most dominant natural resource is gas (Longley et al., 2002). The NWS is a world-class gas province, with estimated reserves of 1.47 trillion cubic metres, making up the vast majority of the O&G reserves on the NWS (Longley et al., 2002). Exploration drilling commenced in 1953, and today there are around 60 production facilities and thousands of kilometres of subsea pipelines on the NWS (Bond et al., 2018b; Geoscience Australia, 2009; Longley et al., 2002). The production facilities are diverse in their design and include: semi-submersible platforms; floating production, storage, and offloading vessels (FPSOs); monopods; conventional steel jacket structures; and concrete gravity structures (CGS). The NWS facilities also include the Shell Prelude and Ichthys Explorer, the world’s largest FPSO and semi-submersible platform respectively (Gust et al., 2019; Marshall and Grose, 2014). The infrastructure on the NWS is generally sparsely distributed over a distance of some 2,000 km, from offshore of Exmouth in the south to the Timor Sea in the north. However, approximately two thirds of the production facilities on the NWS are found in the Carnarvon Basin (Geoscience Australia, 2009). The NWS has a diverse range of marine habitats and is one of the world’s biodiversity hotspots (Roberts et al., 2002; Wilson, 2013). These habitats include mangroves, coral 10 Ch 1: General Introduction reefs, offshore shoals, submarine canyons, and macrobenthos communities (Commonwealth of Australia, 2012a; Fromont et al., 2016; Wilson, 2013). Some areas of the NWS are globally recognised areas of ecological importance, including the Ashmore Reef Ramsar Wetland and the Ningaloo Coast World Heritage Area (Anon., 2018; Ramsar Convention Secretariat, 2013). The high diversity and productivity of the NWS are driven by multiple factors: it is mostly shallow, with 40% of the area being less than 200 m deep; it is a sink for tropical species from the Indo-West Pacific via the Indonesian Throughflow (ITF) current; and large internal tides encourage mixing of waters across depths, bringing nutrients into surface waters (Anon., 2018; Holloway, 2001; Richards et al., 2015; Wilson, 2013). The NWS is inhabited by globally significant populations of various marine organisms (Anon., 2018). The Pilbara region of the NWS is a hotspot for sponges, while the southern Kimberley and northern Pilbara are hotspots for threatened elasmobranchs, including sawfishes Pristis spp. and northern river sharks Glyphis garricki (Fromont et al., 2006; Morgan et al., 2011). Large sharks are abundant along most of the NWS coast (Letessier et al., 2019). Whale sharks Rhincodon typus and reef mantas Mobula alfredi aggregate along the Ningaloo Reef, and humpback whales Megaptera novaeangliae migrate southwards along the NWS from June to October each year (Commonwealth of Australia, 2012a; Wilson et al., 2003). However, apart from known aggregations at a limited number of locations, research into the ecology of much of the NWS is lacking (Wilson, 2013). Research associated with O&G production has provided insight into particularly understudied parts of the NWS. By 1985, the only knowledge of inshore fish fauna in the Dampier region was from environmental impact studies carried out by Woodside Petroleum and Dampier Salt (Blaber et al., 1985). Over the past decade there have been several ecological studies conducted on the O&G infrastructure of the NWS. These studies have recorded various threatened marine species including green sawfish Pristis zijsron, whale sharks, grey nurse sharks Carcharias taurus, and oceanic mantas Mobula birostris (Bond et al., 2018a; McLean et al., 2019). Novel behavioural records have also been reported, including pufferfish Torquigener sp. nests at mesophotic depths previously only observed in Japan (Bond et al., 2020a), and the first wild record of pre-copulatory behaviour in leopard sharks Stegostoma tigrinum (Birt et 11 Ch 1: General Introduction al., 2019). Offshore platforms on the NWS are inhabited by diverse fish communities, including reef-dependent and pelagic species, and have been shown to support full age-structured populations of the red-belted anthias Pseudanthias rubrizonatus (Fowler and Booth, 2012; Pradella et al., 2014). Both platforms and pipelines also provide habitat for commercially important fish species, including saddletail snapper Lutjanus malabaricus, goldband snapper Pristipomoides multidens and mangrove jack Lutjanus argentimaculatus (Bond et al., 2018b; McLean et al., 2017, 2019; Pradella et al., 2014). Bond et al. (2018b) also found that diversity and abundance of fishes were both significantly higher on pipelines than in adjacent natural habitats, with biomass of commercial species 7.5 higher on the pipelines. Industry-funded research therefore provides the means and opportunity for us to better understand the ecology and behaviour of animals in understudied regions such as the NWS. 1.5 AIMS OF RESEARCH Australia’s NWS is a marine biodiversity hotspot that is also populated with various types of offshore infrastructure. There is growing evidence that these structures are important habitats for threatened marine megafauna and commercially important fish species. Research into the offshore platforms of the NWS not only increases our knowledge of the ecosystems created by offshore platforms, but also provides insight into an understudied biodiversity hotspot. Australia’s decommissioning legislation is currently under review; however little is known about the marine communities associated with the many offshore platforms in Australian waters (Taylor 2020). It is critical that the ecological roles played by Australia’s offshore platforms are understood before decommissioning decisions are made, as potentially valuable ecosystems could be lost. Other regions around the world have recognised the importance of the ecosystems created by offshore platforms, and have implemented successful RTR programs to retain these ecosystems. Australia can learn from both successful and failed RTR programs, and use scientific research to make evidence-based decommissioning decisions. 12 Ch 1: General Introduction The goals of this PhD dissertation are firstly to determine whether the presence of offshore platforms, both on the NWS and globally, results in the emergence of novel ecosystems; and secondly to expand our understanding of the marine communities associated with offshore platforms, and the role these platforms play in a regional context. The key questions that my PhD will explore are:  Can offshore platforms around the world be classified as novel ecosystems? This question is explored in Chapter 2: van Elden S, Meeuwig JJ, Hobbs RJ, Hemmi JM. 2019. Offshore Oil and Gas Platforms as Novel Ecosystems: A Global Perspective. Frontiers in Marine Science 6: Article 548.  Has a novel ecosystem emerged in the Wandoo field on Australia’s NWS? This question is explored in Chapter 3: van Elden S, Meeuwig JJ, Hobbs RJ. 2020. Offshore platforms as novel ecosystems: a case study from Australia’s Northwest Shelf. Global Change Biology. In prep.  How does ecological research around offshore platforms provide insight into animal behaviour? This question is explored in Chapter 4: van Elden S, Meeuwig JJ. 2020. Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi). Marine Biodiversity 50:93  Do offshore platforms create refuges for threatened elasmobranchs? This question is explored in Chapter 5: van Elden S, Meeuwig JJ. 2020. Elevated abundance of threatened elasmobranchs at an offshore oil field in Australia. Conservation Biology. Submitted. 13 Ch 1: General Introduction 1.6 APPROACH TO THESIS FIELD STUDIES AND STATISTICAL ANALYSIS The overall approach to this thesis is empirical, sensu Peters (1991), and is comparative rather than experimental. The installation of the Wandoo infrastructure represents a natural experiment (Barley and Meeuwig, 2017), as the potential emergence of a novel ecosystem was not the intent at the time of installation. This natural experiment provides an opportunity to test hypotheses with respect to offshore platforms as novel ecosystems. The Wandoo infrastructure allows for these hypotheses to be tested at ecologically relevant temporo-spatial scales that would not be feasible in a controlled experiment. True replicates of the Wandoo field do not exist, making this an “n=1 experiment”, however such unreplicated natural experiments provide unique opportunities to test hypotheses at the ecosystem scale (Barley and Meeuwig, 2017). Field studies The data underpinning this thesis were collected during six field surveys in the area of the Wandoo field, carried out every austral autumn and spring for three years. The Wandoo field is located 75 km northwest of Dampier, Western Australia, in waters approximately 50 m deep. The infrastructure in the Wandoo field has been in place for over 25 years, and includes: a catenary anchored leg mooring (CALM) buoy, secured by six moorings around the pipeline end manifold (PLEM); Wandoo A, an unmanned monopod platform consisting of production infrastructure with a helideck supported by a 2.5 m diameter shaft; and Wandoo B, a concrete gravity structure (CGS) with a caisson measuring 114 m long by 69 m wide, and four shafts 11 m in diameter supporting the superstructure 18 m above the surface (Fig. 1.2). Commercial and recreational vessel access is restricted in the Wandoo field, with no unauthorised entry into the 500 m petroleum safety zone surrounding all infrastructure (Commonwealth of Australia, 2010). In addition to the Wandoo field, two natural sites were also studied to provide “controls” for the platform. The first natural site, Control Sand (CS), was selected as a proxy for the Wandoo field prior to the installation of infrastructure. The region was extensively trawled in the 1970s and 1980s (Sainsbury et al., 1993), simplifying habitat from characterised by macrobenthos to ones characterised by sand. This site is located 15 km northeast of the Wandoo field, in similar water depths of 14 Ch 1: General Introduction approximately 50 m. The CS site is key to understanding whether a novel ecosystem has emerged in the Wandoo field, as novel ecosystems have been biotic and abiotic components different from those that prevailed historically (Hobbs et al., 2013a). Comparisons between the Wandoo field and the CS site allow for assessment of the broad, ecosystem-level changes that may have occurred in the Wandoo field over the last 25 years. The second site, Control Reef (CR), was selected to compare the ecology of the artificial reef (the Wandoo infrastructure) with a comparable natural reef. This Figure 1.4 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale. rocky reef is located approximately 15 km west of the Wandoo field, has a similar seabed footprint to the Wandoo infrastructure, and rises to around 35 m from the 50 m deep seabed. The CR site is a proxy for Wandoo under a “topping” decommissioning scenario, where the midwater portions of the structure would be removed (Dauterive, 2000). Surveys were carried out a minimum of 50 m away from any infrastructure at the Wandoo site so as to avoid collision and or entanglement with the infrastructure. To ensure consistency in data collection, surveys at the CR site were carried out a minimum of 50 m away from the reef structure. 15 Ch 1: General Introduction I chose seabed and mid-water stereo-BRUVS as the sampling method chosen for these field surveys. Stereo-BRUVS consist of two GoPro cameras mounted on a horizontal basebar, converging to a common focal point at an angle of four degrees per camera. Seabed stereo-BRUVS are baited with ~800 g of pilchards Sardinops sp., placed in a bag made of plastic coated wire or galvanised steel mesh. The bait bag is attached to a bait arm extending 1.5 m in front of the horizontal base bar. Seabed stereo-BRUVS are deployed on the seabed according to established field protocols (Langlois et al., 2018), and record the animals that enter the field of view over a period of one hour. Midwater stereo-BRUVS are baited with 1 kg of crushed pilchards placed in a perforated polyvinyl chloride (PVC) canister. This canister is fixed to the end of a bait arm extending 1.5 m from the horizontal basebar. Mid-water stereo-BRUVS are suspended ten metres below the surface and record for two hours, due to pelagic taxa generally being more sparsely distributed than demersal taxa. Mid-water stereo-BRUVS are deployed according to established field protocols (Bouchet et al., 2018b). Prior to fieldwork, stereo-BRUVS are calibrated in an enclosed swimming pool using the CAL software (SeaGIS Pty Ltd, 2020), following established calibration protocols (Harvey and Shortis, 1998). Collected videos are converted to Audio Video Interleave (AVI) format using Xilisoft Video Converter Ultimate (Xilisoft Corporation, 2016) before being imported into the EventMeasure software package (SeaGIS Pty Ltd, 2020) for processing. A slow hand clap is recorded in the shared field of view of each stereoBRUVS rig prior to deployment. This hand clap is used to synchronise the left and right cameras videos in the lab prior to processing. Processing commences either once the seabed stereo-BRUVS have settled on the substrate or once the mid-water stereoBRUVS have stabilised at the set depth of 10 m. All animals are identified to the lowest possible taxonomic level. Relative abundance is estimated as the maximum number of individuals of a given species in a single frame (MaxN; Cappo et al., 2006). Stereo-BRUVS provide a variety of data. Abundance is determined using MaxN, which is the maximum number of individuals of a given taxa recorded in a single video frame (Cappo et al., 2006). Due to the difficulty in distinguishing between individuals, MaxN likely results in underestimation of biomass (Kilfoil et al., 2017). However, MaxN is 16 Ch 1: General Introduction designed to avoid double counting of individuals and therefore is a more conservative estimate of abundance. Diversity is determined by the identification of all animals to the lowest possible taxonomic level. Not all taxa can be readily identified to species, particularly in mid-water environments where many species have counter-shaded and/or reflective colouration (Santana-Garcon et al., 2014). The stereo camera design of stereo-BRUVS allows for animals to be measured, and the weight of animals can be calculated using known length-weight relationships. The data derived from stereoBRUVS surveys is the basis for Chapters 3-5 of this dissertation, as well as Appendix 1. The potential effects of environmental variables and human impact on the abundance and biomass of marine fauna were also analysed. A database of physical, chemical, biological, and anthropogenic variables was compiled. Travel time variables were based on human accessibility calculations undertaken by Maire et al. (2016). Distance to market and population were calculated using the LandScan 2016 database (Dobson et al., 2000), and distances to marine features were calculated using bathymetry data following Yesson et al. (2020). Environmental data were derived from the following datasets:  Geoscience Australia (GA) 250 m bathymetry (Whiteway, 2009);  GA Australian submarine canyons (Huang et al., 2014);  CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and,  Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020). Statistical analysis In this dissertation, I use a variety of statistical methods to analyse the diverse data in the thesis, depending on the nature of the data itself and the sub-hypothesis being tested. The core analyses are generally permutational, whether applied to univariate or multivariate data. Permutation-based statistical methods were chosen because they are robust to heterogeneity in the data while still maintaining statistical power (Anderson, 2017). The nature of the field surveys lend themselves to testing at the levels of year and season, and therefore most analyses are also based on 17 Ch 1: General Introduction permutational analysis of variance (ANOVA). I did not use repeated measures ANOVA as the samples across the surveys were selected randomly within the stratified sampling design and were thus independent of those samples in the previous surveys (Zar, 1999). I did not use a Bonferroni correction following the advice of Armstrong (2014) as (1) I had a restricted number of planned comparisons and (2) I was more concerned about a type II error than a type I error, i.e. that a difference existed but none was detected; in other words, where a novel ecosystem had emerged but I failed to detect it. The univariate measures of abundance, biomass and fork length were log10 transformed to stabilise variance (Zar, 1999), and Euclidean distance matrices were calculated prior to application of permutational multivariate analysis of variance (PERMANOVAs; Anderson, 2017). For multivariate analyses, abundance and biomass data were log(x+1) transformed to increase the influence of rare taxa and reduce the influence of common taxa, and Bray-Curtis resemblance matrix were calculated. Multivariate analyses were visualised using canonical analysis of principal coordinates (Anderson and Willis, 2003). When analysing environmental variables, a Pearson’s correlation was run to identify highly correlated independent variables with a correlation coefficient >0.6 (Havlicek and Peterson, 1976). Analyses included only one of any highly correlated variables in a given test. A distance‐based linear model (DistLM) was used to determine the relationship between these variables and the assemblage data. All analyses were completed using the Primer 7 software package with the PERMANOVA+ add-on (Anderson, 2017). In some cases such as for the Wilcoxon Signed Rank tests, and the Chi-square contingency tests where the response variable was counts, the analyses were calculated by hand in Microsoft Excel (Microsoft Corporation, 2013). 1.7 ADDITIONAL INFORMATION During my PhD I compared the data I obtained from the Wandoo platform using stereo-BRUVS, with data obtained from ROV surveys by Thomas Tothill for his Master’s Thesis (Tothill, 2019). This led to the development of a standardised method for using a combination of ROV and stereo-BRUVS to more effectively sample the three- 18 Ch 1: General Introduction dimensional habitat created by offshore platforms. This work is presented here as Appendix 1: van Elden S, Tothill T, Meeuwig JJ. 2020. Strategies for obtaining ecological data to enhance decommissioning assessments. The APPEA Journal 60.2. 559–562 1.8 SUMMARY There are thousands of offshore platforms installed throughout the world’s oceans, which contribute a large percentage of global energy for consumption. These platforms operate for decades before they are decommissioned, which in most cases involves the complete removal of the platform from the marine environment. However, over the course of their productive lives, offshore platforms function as artificial reefs establishing complex marine communities and acting as aggregation sites for pelagic megafauna. Some regions have recognised the value of these artificial reef structures and allow for in situ decommissioning in the form of RTR programs. The emergence of new marine communities around offshore platforms is congruent with the novel ecosystem concept, which recognises the potential ecological value of ecosystems altered by human activity. However, the novel ecosystem concept has only been applied to a handful of marine ecosystems and only been used twice to describe offshore platforms. Australia’s NWS is not only rich in O&G resources, but is also a marine biodiversity hotspot with globally significant populations of several marine species (Anon., 2018). The offshore platforms on the NWS are distributed across an area containing internationally recognised ecosystems and megafauna aggregation sites (Venables et al., 2016; Purcell and Purcell, 1988). The ecology of much of the NWS, particularly offshore, remains poorly studied. Offshore platforms represent a unique opportunity for expanding our knowledge of this diverse and productive region. Research on these platforms so far has reported endangered species, unique behaviours, and important habitats for commercial fish species. However, these potentially important ecosystems could be lost due to decommissioning without fully being understood. 19 Ch 1: General Introduction This dissertation will focus on the application of the novel ecosystem concept to offshore platforms, both globally and on the NWS. Offshore platforms represent unique marine ecosystems, and I will assess offshore platform-associated communities within the context of communities in natural habitats, to determine the regional role these platforms play on the NWS. Offshore platforms provide us with the opportunity to study remote, otherwise undervalued areas of the ocean. Recent reports have found that these remote areas are ideal locations for discovering unique animal behaviours (Birt et al., 2019; Bond et al., 2020a; Haugen and Papastamatiou, 2019). 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Res., 26–31. doi:10.1109/CHUSER.2012.6504275. 30 Ch 2: Offshore Platforms as Novel Ecosystems CHAPTER 2 OFFSHORE OIL AND GAS PLATFORMS AS NOVEL ECOSYSTEMS: A GLOBAL PERSPECTIVE van Elden S, Meeuwig JJ, Hobbs RJ, Hemmi JM. 2019. Offshore Oil and Gas Platforms as Novel Ecosystems: A Global Perspective. Frontiers in Marine Science 6: Article 548. K EYWORDS : NOVEL ECOSYSTEMS , R IGS - TO -REEFS , DECOMMISSIONING , ARTIFICIAL REEFS , ENVIRONMENTAL IMPACTS , OFFSHORE OIL AND GAS 2.1 ABSTRACT Offshore oil and gas platforms are found on continental shelves throughout the world’s oceans. Over the course of their decades-long life-spans, these platforms become ecologically important artificial reefs, supporting a variety of marine life. When offshore platforms are no longer active they are decommissioned, which usually requires the removal of the entire platform from the marine environment, destroying the artificial reef that has been created and potentially resulting in the loss of important ecosystem services. While some countries allow for these platforms to be converted into artificial reefs under Rigs-to-Reefs programs, they face significant resistance from various stakeholders. The presence of offshore platforms and the associated marine life alters the ecosystem from that which existed prior to the installation of the platform, and there may be factors which make restoration of the ecosystem unfeasible or even detrimental to the environment. In these cases, a novel ecosystem has emerged with potentially significant ecological value. In restoration ecology, ecosystems altered in this way can be classified and managed using the novel ecosystems concept, which recognizes the value of the new ecosystem functions and services and allows for the ecosystem to be managed in its novel state, instead of being restored. Offshore platforms can be assessed under the novel ecosystems concept using existing decommissioning decision analysis models as a base. With thousands of platforms to be decommissioned around the world in coming decades, the novel ecosystems concept provides a mechanism for recognizing the ecological role played by offshore platforms. 31 Ch 2: Offshore Platforms as Novel Ecosystems 2.2 INTRODUCTION Since 1947, when Ship Shoal Block 32 in the Gulf of Mexico became the world’s first offshore oil drilling platform (Aagard and Besse, 1973), the offshore energy industry expanded rapidly to currently number over 12,000 offshore installations globally (Ars and Rios, 2017). Offshore platforms are situated on the continental shelves of 53 countries, making offshore oil and gas production a major global industry (Parente et al., 2006). Significant advances in engineering over the last 70 years have not only increased the number of rigs, but also the environmental conditions which they can withstand: offshore platforms are now larger and found in deeper waters, further from shore. These technological advances have implications for decommissioning, which occurs when hydrocarbon production ceases or the lease ends and the platform is shut down. The decommissioning process now takes longer, requires more specialized equipment and, by extension, has become more costly (Kaiser and Liu, 2014). A 2016 study by the IHS Markit forecast the global decommissioning of over 600 offshore structures between 2017 and 2021, with a further 2,000 projects by 2040, resulting in a total cost between 2010 and 2040 of US $210 billion (IHS Markit, 2016). In countries where total removal is the legal requirement, decommissioning involves the plugging of wells, cleaning, capping and possibly removal of pipelines, removal of production equipment and removal of the structure (Hakam and Thornton, 2000). In United Kingdom waters alone, decommissioning expenditure is forecast to amount to £17 billion between 2017 and 2025 (Oil and Gas UK, 2017). Even a nation with comparatively low oil and gas production, such as Australia (0.9% of global production), has a future decommissioning liability of US $21 billion over the next 50 years (NERA, 2016). The process of decommissioning is far from straightforward in many cases, and is often complicated by the process of transferability, whereby an existing platform is sold to a company which can continue production at lower profit margins (Parente et al., 2006). From a biological viewpoint, increasing evidence suggests that offshore oil and gas platforms provide significant ecosystem services while active. The installation of these platforms creates hard substrate in open waters which is colonized by a variety of 32 Ch 2: Offshore Platforms as Novel Ecosystems sessile organisms and results in the formation of artificial reefs (Shinn, 1974; Scarborough-Bull, 1989). Because they may exclude commercial fishing, particularly trawling, and in some cases recreational fishing, these platforms can also act as important refuges for a variety of taxa (Frumkes, 2002; Claisse et al., 2014). The potential ecological value of offshore platforms raises the question of whether there may be alternatives to the standard decommissioning process that might have important positive ecological outcomes, and ecological factors are more recently being included in decommissioning assessments (Fowler et al., 2014; Henrion et al., 2015; Sommer et al., 2019). The successes of various Rigs-to-Reefs projects, particularly in the Gulf of Mexico, have demonstrated that these structures can be effectively repurposed as artificial reefs (Frumkes, 2002; Kaiser and Pulsipher, 2005; Sammarco et al., 2014). However, to date only a few countries around the world have successfully implemented Rigs-to-Reefs programs (summarized in Bull and Love, 2019). Evaluating offshore platforms as novel ecosystems would provide a mechanism for considering the ecological importance of these platforms in the decommissioning process. Novel ecosystems is a relatively recent ecological concept, brought into focus by Hobbs et al. (2006), where human activity has altered ecosystems to a point where restoration may not be feasible. In a world that is increasingly being altered by human activity, the concept of novel ecosystems recognizes that in some cases, ecosystems changed from their historical state by human intervention may not feasibly be able to be restored (Hobbs et al., 2006). With many case studies throughout a variety of ecosystems around the world (Hobbs et al., 2013b), novel ecosystems provide an approach for recognizing value in altered ecosystems, rather than implementing restoration for restoration’s sake. In the cases of both active and decommissioned platforms, it is possible that the concept of novel ecosystems can be applied as a way to describe the ecosystems created by the presence of the platforms. The aim of this review is to evaluate the ecological role of offshore oil and gas platforms, and to assess these platforms against the criteria of the novel ecosystems concept. 33 Ch 2: Offshore Platforms as Novel Ecosystems 2.3 DECOMMISSIONING Decommissioning, the end of life stage for offshore infrastructure, is a process which is regulated internationally, regionally and nationally. The 1996 Protocol to the London Dumping Convention (London Protocol) aimed to protect the marine environment from all sources of pollution, and regulates against the dumping of “... platforms or other man-made structures at sea; and any abandonment or toppling at site of platforms or other man-made structures at sea, for the sole purpose of deliberate disposal.” (Elizabeth, 1996). However, the London Protocol does not expressly prohibit decommissioning of structures in situ (Techera and Chandler, 2015), stating that dumping does not include “placement of matter for a purpose other than disposal thereof, provided that such placement is not contrary to the aims of this Protocol (Elizabeth, 1996).” There are four alternatives to complete removal: (1) leave wholly in place with appropriate navigational aids; (2) partial removal, usually of the superstructure); (3) tow-and-place by moving the structure to a new location; and (4) toppling by laying the structure on its side (Schroeder and Love, 2004; Macreadie et al., 2011; Fowler et al., 2014). Decommissioning regulations and options in various countries and regions have been reported on and assessed extensively in the literature. While decommissioning in the North Sea and the United States (US) has been well studied (e.g., Reggio, 1987; Löfstedt and Renn, 1997; Dauterive, 2000; Cripps and Aabel, 2002; Schroeder and Love, 2004; Kaiser and Pulsipher, 2005; Jørgensen, 2012; Claisse et al., 2015), there has been more recent focus on decommissioning policy in relatively “new” oil and gas producing regions, such as south-east Asia (Zawawi et al., 2012; Al-Ghuribi et al., 2016; Fam et al., 2018; Laister and Jagerroos, 2018), Australia (Fowler et al., 2015; Techera and Chandler, 2015; Chandler et al., 2017), and Brazil (Barros et al., 2017; Mimmi et al., 2017). Two recent reviews (Bull and Love, 2019; Sommer et al., 2019) provide comprehensive assessments of the literature on the decommissioning process, options, and regulations around the world. These two reviews complement each other by focusing on somewhat different aspects of decommissioning. Sommer et al. (2019) focuses on the ecosystem functions and services provided by platforms, and suggests a 34 Ch 2: Offshore Platforms as Novel Ecosystems more ecosystemsbased approach to decommissioning. Bull and Love (2019) provides the most in-depth review to date of the literature on offshore oil and gas platforms, including platform installation, decommissioning, relevant legislation, and platform ecology. While this review is mainly focused on the United States, it does briefly review Rigs-to-Reefs programs in other regions around the world. 2.4 RIGS-TO-REEFS Rigs-to-Reefs is a potential decommissioning outcome for offshore oil and gas structures whereby obsolete infrastructure is re-purposed as artificial reefs instead of being brought back to shore for disposal (Kaiser and Pulsipher, 2005). The first examples of Rigs-to-Reefs occurred in the 1980s, when platforms were removed from production in Louisiana and transported to Florida where they were repurposed as artificial reefs (Kaiser, 2006; Jørgensen, 2009). By April 2018, approximately 532 offshore platforms have been re-purposed as artificial reefs in the Gulf of Mexico, mostly in Louisiana and Texas (Ajemian et al., 2015; Bureau of Safety and Environmental Enforcement, 2018). This represents just over 11% of the total number of platforms decommissioned in the Gulf of Mexico (Bull and Love, 2019). Offshore oil and gas platforms are spatially complex structures and their value as artificial reefs has been discussed in numerous studies (Shinn, 1974; Dugas et al., 1979; Bohnsack and Sutherland, 1985; Guerin et al., 2007). Offshore platforms have not only been shown to have a higher fish biomass than sandy bottom areas but even natural reefs (Claisse et al., 2014). This results in offshore platforms having an “enhanced fishing zone” of 200–300 m for pelagic species and 1–100 m for demersal species (Bohnsack and Sutherland, 1985). Fishing and diving around offshore rigs, in countries where it is allowed, is a major component of the local tourism industries (Stanley and Wilson, 1989). In Louisiana, recreational fishing is centered around offshore platforms – over 70% of recreational fishing trips into the EEZ are in direct association with offshore platforms, where pelagic fish densities are 20–50 times higher than surrounding areas (Dugas et al., 1979; Reggio, 1987; Dauterive, 2000). As such, sport fishers and recreational divers generally support Rigs-toReefs programs (Frumkes, 2002). 35 Ch 2: Offshore Platforms as Novel Ecosystems Both active and decommissioned offshore platforms can have a negative impact on commercial trawl fishing, and the prevention of trawling is a common criticism of Rigsto-Reefs programs (Macdonald, 1994; Hamzah, 2003). The issue of allowing fishing around platforms is one that is still uncertain and needs to be handled carefully. In some cases where platforms have become key habitat for threatened or economically important species, it may be prudent to continue to exclude all fishing from these areas if they are converted into artificial reefs, as they can then be used to bolster populations at surrounding natural reefs where fishing occurs in the same way that marine protected areas (MPAs) do (Mcclanahan and Mangi, 2000). In sandy, flat-bottom areas with generally limited physical structure, such as the northwest shelf of Australia, the Adriatic Sea and parts of the North Sea, offshore platforms present some of the only obstacles to trawl nets (Rijnsdorp et al., 1998; Wassenberg et al., 2002; Fabi et al., 2004). While the prevention of trawling is detrimental to commercial fisheries, it is ecologically beneficial in offering protection to benthic habitats; in a study to determine the effect of trawling on sponge communities of the north-west shelf of Australia, sponges were caught in 85% of trawls, with a mean catch of 87.2 kg per half-hour (Wassenberg et al., 2002). Evidence on the success of Rigs-to-Reefs programs and the suitability of oil platforms as artificial reef habitat suggests that these structures can provide significantly more ecological value than other cases of “dumping” (Ajemian et al., 2015). However, it is important to note that just because Rigs-to-Reefs has been successful in a certain area (e.g., the Gulf of Mexico), it does not mean it would automatically be an ecologically beneficial exercise in the North Sea, California or Australia. Every ecosystem is different and needs to be evaluated as such; creating a reef, simply because there is a platform that needs to be decommissioned, is indeed little more than waste disposal (Macdonald, 1994; Salcido, 2005). A major obstacle in the path of Rigs-to-Reefs legislation is the relative lack of ecological research on offshore structures. For example, despite the presence of over 40 offshore oil and gas installations on the continental shelf of north-west Australia, there has been a limited number of published studies on the ecology of the structures in this 36 Ch 2: Offshore Platforms as Novel Ecosystems region (e.g., Fowler and Booth, 2012; Pradella et al., 2014; McLean et al., 2017, 2018; Bond et al., 2018). Macreadie et al. (2012) concluded that environmental research must be part of the development of Rigs-to-Reefs policy, pointing to the case of California, where a Rigs-to-Reefs bill was vetoed in 2001 based on a lack of evidence that reefed platforms produce net environmental benefits. Macreadie et al. (2012) argue that the subsequent successful passing of a Rigs-to-Reefs bill in 2010 was due in large part to the years of subsequent research by Dr. Milton Love and colleagues (Schroeder and Love, 2002, 2004; Love et al., 2006). 2.5 ECOLOGY OF OFFSHORE PLATFORMS Offshore oil and gas platforms can play important ecological roles for various taxa (Friedlander et al., 2014). They provide substrate for sessile organisms such as sponges and corals and act as a refuge for fish and megafauna such as seals and whales (Forteath et al., 1982; Todd et al., 2016). When a platform is installed, the establishment of a faunal community occurs quickly, with fish appearing within hours (Bohnsack, 1989), and ecological succession results in a complex reef-type habitat within 5–6 years (Driessen, 1986). Offshore platforms can be an important source of habitat not only for fish, but also for sessile invertebrates where hard substrate is limited. Where offshore platforms are isolated from natural reefs, the free-swimming larval stages of invertebrates that settle on offshore platforms would otherwise not likely survive due to a lack of “hospitable” substrate (Driessen, 1986; Thomson et al., 2003; Macreadie et al., 2011). However, the addition of hard substrate means that offshore platforms can also provide habitat for invasive species (Page et al., 2006; Pajuelo et al., 2016). There is considerable debate as to whether fish associated with artificial structures are actually being produced there for a net gain, or are simply being attracted from nearby natural reefs. Attraction is thought to be detrimental to fish populations, especially those which are targeted by fisheries, as previously sparsely distributed populations become concentrated, making them vulnerable to exploitation (Bohnsack, 1989). However, in the case of offshore platforms, attraction could be beneficial to pelagic species in some regions, where the platforms can act as a temporary refuge from 37 Ch 2: Offshore Platforms as Novel Ecosystems fishing pressure. Macreadie et al. (2011) discuss the importance of habitat limitation as a factor in the attraction vs. production debate; specifically that a habitatlimited fish population would see an increase in regional biomass due to the addition of suitable habitat via artificial structures. Fowler and Booth (2012) found that offshore platforms in northwest Australia could sustain complete size- and age-structured populations of the Serranidae Pseudanthias rubrizonatus, with a presumed age range in sampled individuals of 22 days to 5 years. However, production of fish varied among individual platforms. The relative scales of “attraction vs. production” therefore may vary between offshore oil and gas platforms, as biotic and abiotic conditions vary from platform to platform. The presence of larval fish may not be enough to assume production, based on the proximity of other reefs (Bohnsack, 1989; Macreadie et al., 2011). In addition, production is more important in the case of demersal species, which are more dependent on benthic habitat than highly mobile pelagic species (Bohnsack, 1989). The ecosystem created by offshore platforms means, like natural reefs, they provide economic benefits. In regions where recreational fishing is permitted, these platforms have been highly popular locations for decades (Dugas et al., 1979). “Fishing the rigs” is a major portion of the recreational fishing activity in the Gulf of Mexico, particularly Louisiana, where species caught at the platforms include sharks, billfish, and barracuda (Driessen, 1986). While recreational fishing occurs around offshore platforms, a number of commercial gear types such as trawl and longline are generally excluded from the waters around these structures due to the risk of damage to both fishing gear and subsea infrastructure such as pipelines (de Groot, 1982; Demestre et al., 2008). In some regions, the exclusion of all vessels, including recreational and commercial fishers, can be legally mandated, and these “exclusion zones” vary in size between countries. In the North Sea, the exclusion from fishing around offshore oil platforms that have been in place for decades, has resulted in a network of de facto MPAs (de Groot, 1982; Fujii and Jamieson, 2016). In Australia, the “petroleum safety zones” surrounding offshore platforms extend up to 500 m from the outer edge of any well or structure (Commonwealth of Australia, 2010), while the exclusion zone around a 38 Ch 2: Offshore Platforms as Novel Ecosystems drilling platform in the Jubilee Field in Ghana is five nautical miles (Chalfin, 2018). In 2003, Mexico created an “area of exclusion” of 5,794 km2 around oil platforms in the Campeche region of the Gulf of Mexico (Quist and Nygren, 2015). Various studies have described oil platforms around the world as de facto MPAs. Because of the exclusion of trawl fishing at all platforms in Gabon, and the exclusion of all types of recreational fishing at some platforms due to security restrictions, Friedlander et al. (2014) concluded that these platforms are functioning as de facto MPAs. In California, offshore oil platforms provide a significant refuge for commercially important rockfish species (Frumkes, 2002; Claisse et al., 2014; Fowler et al., 2015). Marine vessels are discouraged from entering the 150 m buffer zone surrounding platforms, meaning that fishing activity is limited, and Schroeder and Love (2002) found that rockfish surrounding an oil platform were larger and greater in density compared with the populations at recreationally and commercially fished sites. In addition, eight offshore oil and gas platforms off southern California supported 430,000 juveniles of the highly overfished and IUCN Critically Endangered Bocaccio rockfish Sebastes paucispinis, accounting for 20% of the average annual number of surviving juveniles of this species. In these instances, the refuges provide much higher recruitment and survival rates than natural but fished nursery grounds (Love et al., 2006). 2.6 NOVEL ECOSYSTEMS Human activities are transforming ecosystems on a global scale (Foley et al., 2005; Mccauley et al., 2015; Laurance and Watson, 2016). Many studies and conservation efforts focus on restoring altered ecosystems to their historical states (Sanchez-Cuervo et al., 2012; Graham and Mcclanahan, 2013), but over the last two decades, the term “novel ecosystems” has emerged as a way of defining ecosystems altered by human activity, where restoration is at best unlikely (Hobbs et al., 2013a). There has been criticism that the concept may exclude restoration and may provide companies a license to trash ecosystems (Aronson et al., 2014; Murcia et al., 2014). However, the novel ecosystem concept is not intended to replace ecological restoration, but is meant to provide a management option for ecosystems where restoration is not 39 Ch 2: Offshore Platforms as Novel Ecosystems feasible or may actually result in the loss of ecosystem value (Hobbs et al., 2014). In some cases, the novel ecosystem may provide ecosystem services that are more beneficial than those provided by the historical state. Backstrom et al. (2018) have suggested that the novel ecosystems concept is most useful in a decision or management context and in terms of meeting social, ecological and economic objectives. The term novel ecosystems was first used in 1997 (Chapin and Starfield, 1997) but was introduced into terrestrial conservation and restoration ecology fields in 2006 (Hobbs et al., 2006). The concept has more recently been adopted by some marine ecologists, where studies on marine novel ecosystems have generally focused on coral reefs which have been altered by direct human activity, disease, climate change or introduced species (Graham et al., 2013, 2015; Yakob and Mumby, 2013; Hehre and Meeuwig, 2015). However, the concept has not yet gained significant traction amongst marine ecologists. Schläppy and Hobbs (2019) provide a comprehensive decisionmaking framework for applying the novel ecosystems concept to altered marine ecosystems. This framework creates a mechanism for the novel ecosystems concept to be more widely applied to marine ecosystems in future. While Schläppy and Hobbs only briefly discuss offshore platforms, Sommer et al. (2019) suggest that the ecosystem-level shifts occurring around offshore platforms are “consistent with the science on... novel ecosystems.” However, while drawing parallels between offshore platforms and novel ecosystems, the authors do not explore the concept further, nor do they discuss the application of the concept to some or all offshore platforms. The degree to which offshore platforms can usefully be considered a novel ecosystem may assist in assessing decommissioning options. Offshore platforms can be broadly assessed in a novel ecosystems context by evaluating these platforms against the criteria outlined in the most recent novel ecosystems definition from Hobbs et al. (2013b): Criterion 1: The abiotic, biotic and social components of the system “differ from those that prevailed historically.” In the case of offshore oil and gas platforms, the abiotic and biotic states of the target ecosystem have clearly been altered due to 40 Ch 2: Offshore Platforms as Novel Ecosystems anthropogenic forcing, specifically due to the installation of a large artificial structure and the associated disturbance of the ecosystem. Examples of this include the growth of cold-water corals on platforms in the North Sea (Gass and Roberts, 2006) and the aggregation of whale sharks around platforms in Qatar (Robinson et al., 2013) both of which are novel qualities not previously present in the historical state of the ecosystem. Criterion 2: The ecosystems have a “tendency to self-organize and manifest novel qualities without intensive human management.” In the case of offshore oil and gas platforms, the marine life associated with offshore platforms is not managed in any way, apart from limited maintenance cleaning to remove sessile invertebrates. These ecosystems persist over the lifespan of the platform, with reports of thousands of tons of invertebrate growth on the subsea structures of platforms (Foster and Willan, 1979; Culwell, 1997). Novel qualities manifested by platforms include higher productivity of algae and invertebrates (Chou et al., 1992) and higher fish biomass (Love et al., 2006). Criterion 3: Novel ecosystems are prevented from returning to their historical states by practical limitations, in the form of ecological, environmental and social considerations. In the context of offshore platforms, these considerations can include many of the factors evaluated by stakeholders during the decommissioning process (Table 2.1). However, some considerations may be context specific rather than absolute, and vary among regions. For example, in California where there are relatively few platforms, their role in providing habitat for economically important species such as rockfish makes individual platforms ecologically important, particularly as some platforms produce more of these species than others (Schroeder and Love, 2002). Conversely, in an area such as the Gulf of Mexico with thousands of platforms, the ecological value of an individual platform within a regional context is not necessarily as high and therefore may not be an important ecological consideration (Schroeder and Love, 2004). Environmental limitations could prevent the removal of offshore platforms, which means that the ecosystem cannot be returned to its historical state. Complete removal decommissioning is a potentially hazardous process both to the environment and personnel, and particularly in regions with harsh weather conditions, decommissioning 41 Ch 2: Offshore Platforms as Novel Ecosystems could be more of a risk than leaving structures in place (Löfstedt and Renn, 1997; OGP Decommissioning Committee, 2012; Ars and Rios, 2017). Additionally, offshore platforms are known as vectors for invasive species, as they are transported long distances at low speed (Page et al., 2006; Pajuelo et al., 2016). The potential transport and spread of the many sponge, algae, coral, and even fish species associated with platforms, could be a factor preventing platform removal, and therefore restoration to historical state. Perhaps the most significant consideration in the case of offshore platforms is the social aspect. Social factors could prohibit removal of platforms, due to prohibitive costs or platform design making removal unfeasible (Faber et al., 2001; OGP Decommissioning Committee, 2012). The social benefits derived from a platform, in the form of an artificial reef utilized by recreational divers and fishers, could be lost if the platform is removed. Conversely, social opposition to the presence of offshore platforms, as is the case in California (Pietri et al., 2011), or legislation prescribing complete removal, as is the case in Australia (Techera and Chandler, 2015) could lead to the complete removal of platforms, thereby possibly returning the ecosystem to its historical state. It is important to avoid a blanket classification of all offshore platforms as novel ecosystems. Offshore platforms always result in the creation of habitat, but this does not by default mean that they result in novel ecosystems. For example, a platform placed near a natural reef may not significantly alter the abiotic or biotic components of the ecosystem, and may rather act simply as an “extension” of the existing reef. However, a platform placed in an area with little natural hard substrate significantly alters the abiotic nature of the ecosystem by increasing the hard substrate available, leading to changes in the community of species within the ecosystem, thereby transforming the ecosystem from its historical state. The novel ecosystems concept can be applied to offshore platforms, so long as it is applied on a case-by-case basis. This is particularly important if the concept is used as part of the decommissioning process, as there may be incentive for energy companies to suggest platforms are novel ecosystems to avoid the costs associated with complete 42 Ch 2: Offshore Platforms as Novel Ecosystems removal. The concept should therefore be applied conservatively and with robust evidence from ecological studies. Various studies have proposed decision analysis frameworks which assess different decommissioning alternatives based on multiple attributes (e.g., Fowler et al., 2014; Bernstein, 2015; Henrion et al., 2015). Some of these attributes can be placed within the novel ecosystems criteria as demonstrated in Table 2.1. Therefore, an assessment can be made of whether an offshore platform is a novel ecosystem simply by using existing decommissioning analysis tools. From an ecological perspective, decommissioning of offshore platforms is an ecological restoration issue. Novel ecosystems provides a tool for recognizing and retaining ecological value created through human activity, as an alternative to ecological restoration. In the same way, Rigs-to-Reefs provides the same tool, as an alternative to complete platform removal. The decision framework for managing altered marine systems proposed by Schläppy and Hobbs (2019) would be a useful starting point for broadly classifying offshore platforms as novel ecosystems – however, because of the suite of complex, and in some cases contentious, issues surrounding oil and gas platforms, there are more factors that need to be taken into account. In this regard, the decommissioning decision analysis frameworks cited above could be used to assess a platform as a novel ecosystems even if decommissioning isn’t yet being considered. For example, using the PLATFORM computer model for decommissioning analysis, Henrion et al. (2015) evaluated the impact of decommissioning options on attributes such as cost, benthic impacts, fish productivity, and water quality, all of which can be considered under novel ecosystems criterion 3 in this review. 43 Ch 2: Offshore Platforms as Novel Ecosystems Table 2.1 Examples from the literature of practical considerations preventing offshore platform sites from being returned to their historical state. Practical limitations Example Ecological considerations References Refuge for endangered and/or economically important Love et al., 2006 species Proportion of regional hard substrate provided by the Love et al., 2003 platform Attraction of fish from natural habitats, making them Cowan and Ingram, 1999 more vulnerable to fishing Environmental considerations Risk of environmental contamination during removal OGP Decommissioning Committee, 2012 Highly productive ecosystem Claisse et al., 2014 Spread of invasive species during removal/transport Page et al., 2006 Environmental damage caused by use of explosives during removal process Kaiser and Pulsipher, 2003 Disturbance of shell mounds and remobilization of toxic chemical contaminants Phillips et al., 2006 Cost of decommissioning OGP Decommissioning Committee, 2012 Social considerations Platform design making removal unfeasible Parente et al., 2006 Public support for Rigs-to-Reefs programs Kaiser and Pulsipher, 2005 Legal frameworks prescribing complete removal Techera and Chandler, 2015 Public opposition to the presence of platforms Frumkes, 2002 Obstruction to commercial fishing Fabi et al., 2004 2.7 CONCLUSION Offshore oil and gas platforms play an ecological role for a wide variety of marine life, from corals and sponges (Gass and Roberts, 2006; Friedlander et al., 2014), to fish and sharks (Dugas et al., 1979; Schroeder and Love, 2002; Pradella et al., 2014), to marine megafauna (Robinson et al., 2013; Todd et al., 2016). At the end of their productive life, these platforms are generally removed completely and disposed of onshore, effectively removing the hard substrate and associated marine growth from an ecosystem that has developed over upward of 30–40 years (Driessen, 1986; Ferreira and Suslick, 2001). There is strong opposition to offshore drilling, and the negative perceptions of oil companies and their intentions is a big obstacle in the path of Rigs44 Ch 2: Offshore Platforms as Novel Ecosystems to-Reefs programs (Löfstedt and Renn, 1997; Pietri et al., 2011). The costs of decommissioning offshore oil and gas infrastructure over the next 20–30 years run into the tens of billions of US dollars, with thousands of structures set to reach their end-oflife in this period (IHS Markit, 2016; Oil and Gas UK, 2017). In some countries, governments (and therefore taxpayers) cover some of the decommissioning costs; in the North Sea alone, this government expenditure could reach US $6.3 billion (Parente et al., 2006). Conversely, the ecosystems created by these offshore platforms have an intrinsic value in terms of fisheries, tourism, and conservation that cannot be ignored. As such, the ecological cost of decommissioning in the form of the destruction of these ecosystems must be an integral part of the decommissioning debate. Based on the analysis of the novel ecosystems concept, many offshore oil and gas platforms can be defined as novel ecosystems, depending on a variety of factors. These platforms warrant further study, on a case-by-case basis, within the framework of novel ecosystems. This does not mean that restoration of these ecosystems should no longer be considered, as restoration may be feasible in many cases and therefore should be an option when a particular platform is to be decommissioned. However, classifying suitable offshore platforms as novel ecosystems allows for the recognition of the established, yet underappreciated, ecological value that these platforms provide. The novel ecosystems concept can contribute to the consideration of decommissioning options using existing decommissioning decision analysis tools. Hobbs et al. (2017) proposed implementing a portfolio of approaches whereby management goals are based on the relative values of ecosystems. This approach recognizes the importance of altered ecosystems, while still allowing for conservation of high-value unaltered ecosystems. Applying this approach to decommissioning would involve identifying ecologically important platforms to be left in place for the ecosystem services they provide, while focusing decommissioning resources and effort on less ecologically valuable platforms. One of the key arguments against novel ecosystems is that they give companies a “‘license to trash’ or ‘get out of jail’ card” (Murcia et al., 2014). This echoes the core 45 Ch 2: Offshore Platforms as Novel Ecosystems opposition to Rigs-to-Reefs; namely that it is simply an excuse for dumping at sea (Macdonald, 1994). This argument, in both cases, ignores the potential ecological value of anthropogenically altered ecosystems. While it is undeniable that companies benefit financially from Rigs-to-Reefs programs, this does not automatically mean that these programs are environmentally detrimental. It should be possible to ensure that any Rigs-to-Reefs policy is robust and comprehensive enough to ensure that any reefing of offshore platforms will benefit the environment. 2.8 ACKNOWLEDGEMENTS Our thanks to the Vermilion Oil and Gas Australia (Pty) Ltd. for their support of this project. 2.9 STATEMENTS Author Contributions SE and JM conceived the study. SE wrote the first draft of the manuscript. All authors contributed to the manuscript revision, read, and approved the submitted version. Funding This manuscript forms part of the Ph.D. thesis of SE. The Ph.D. is funded by the VOGA Ph.D. Scholarship in Rigs-to-Reefs Ecology, awarded by the University of Western Australia with funds donated by the Vermilion Oil and Gas Australia (Pty) Ltd. Conflict of Interest Statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. 2.10 REFERENCES Aagard, P. 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Decommissioning of offshore platform: A sustainable framework. CHUSER 2012 - 2012 IEEE Colloq. Humanit. Sci. Eng. Res., 26–31. doi:10.1109/CHUSER.2012.6504275. 53 Ch 3: Case study on the Wandoo field CHAPTER 3 OFFSHORE PLATFORMS AS NOVEL ECOSYSTEMS: A CASE STUDY FROM AUSTRALIA’S NORTHWEST SHELF van Elden, S., Meeuwig, J.J., and Hobbs, R. 2021. Offshore platforms as novel ecosystems: a case study from Australia’s Northwest Shelf. Ecology and Evolution. In press. K EYWORDS : O IL AND GAS ; OFFSHORE PLATFORMS ECOLOGY ; DECOMMISSIONING ; STEREO BRUVS; DE FACTO MPA S 3.1 ABSTRACT The decommissioning of offshore oil and gas platforms typically involves removing some or all of the associated infrastructure and the consequent destruction of the associated marine ecosystem that has developed over decades. There is increasing evidence of the important ecological role played by offshore platforms. Concepts such as novel ecosystems allow stakeholders to consider the ecological role played by each platform in the decommissioning process. This study focused on the Wandoo field in Northwest Australia as a case study for the application of the novel ecosystem concept to the decommissioning of offshore platforms. Stereo-baited remote underwater video systems were used to assess the habitat composition and fish communities at Wandoo, as well as two control sites: a sandy one that resembled the Wandoo site pre-installation, and one characterised by a natural reef as a control for natural hard substrate and vertical relief. We found denser macrobenthos habitat at the Wandoo site than at either of the control sites, which we attributed to the exclusion of seabed trawling around the Wandoo infrastructure. We also found that the demersal and pelagic taxonomic assemblages at Wandoo more closely resemble those at a natural reef than those which would likely have been present pre-installation, but these assemblages are still unique in a regional context. The demersal assemblage is characterised by reefassociated species with higher diversity than those at the sand control and natural reef control sites, with the pelagic community characterised by species associated with oil platforms in other regions. These findings suggest that a novel ecosystem has emerged in the Wandoo field. It is likely that many of the novel qualities of this ecosystem would be lost under decommissioning scenarios that involve partial or complete removal. This study provides an example for classifying offshore platforms as novel ecosystems. 54 Ch 3: Case study on the Wandoo field 3.2 INTRODUCTION Offshore oil and gas platforms (hereafter offshore platforms) have been a feature of continental shelf waters for over 70 years, with nearly 12,000 of these structures currently installed around the world (Aagard and Besse 1973, Ars and Rios 2017). When an offshore platform is no longer economically viable, a decision is made on the fate of the structure through a process referred to as decommissioning. In most cases, decommissioning involves complete removal of the platform from the marine environment for scrapping or recycling on land (Schroeder and Love 2004). Complete removal is legislated as the default decommissioning method in many countries and regions, including Australia and the North Sea, as well as internationally under the United Nations Convention on the Law of the Sea (UNCLOS) and the 1996 Protocol to the London (Dumping) Convention (Elizabeth 1996, Techera and Chandler 2015, Chandler et al. 2017). However, the London Convention does permit in situ decommissioning for purposes other than disposal, and some regions have legislated such methods. In the Gulf of Mexico, platforms can be left either wholly or partially in place, or towed to a new location, under a program known as Rigs-to-Reefs (RTR, Reggio, 1987). Offshore platforms have been shown to form highly complex artificial reefs (Shinn 1974), and RTR programs represent a method for preserving and maintaining these artificial reef communities that are established around offshore platforms over the decades they spend in the ocean, similar to the reefs formed by shipwrecks (Dauterive 2000, Leewis et al. 2000). In situ decommissioning is a financially beneficial option for energy companies due to the excessive costs associated with complete removal, (Dauterive 2000), and this motivation is often used as an argument against rigs-toreefs, particularly by environmental groups (Löfstedt and Renn 1997). Offshore platforms play various ecological roles, including acting as aggregation sites for marine megafauna (Robinson et al. 2013, Haugen and Papastamatiou 2019), nurseries for juvenile fishes (Love et al. 2019, Nishimoto et al. 2019), and providing habitat for economically important and overfished species (Love et al. 2006, Bond et al. 2018a). The presence of these offshore platforms creates new habitat, which can have a significant impact on fish production; platforms in 55 Ch 3: Case study on the Wandoo field California are some of the most productive fish habitats in the world, and platforms in Gabon have higher fish biomass than pristine reefs in the Pacific (Claisse et al. 2014, Friedlander et al. 2014). Fishing is excluded around offshore platforms in many countries, either by law as is the current case in Australia (Commonwealth of Australia 2010), or by the presence of subsea infrastructure which can damage fishing equipment (de Groot 1982). The partial or complete exclusion of fishing effectively creates de facto marine protected areas (MPAs) around offshore platforms (de Groot 1982, Friedlander et al. 2014). The exclusion of fishing is particularly important in areas which are overfished, or where hard substrate is limited and infrastructure may be some of the only obstacles to trawling (de Groot 1982, Schroeder and Love 2002, Love et al. 2006, Fujii and Jamieson 2016). There is an increasing research focus around the world on the potential ecological importance of offshore platforms, and particularly on ensuring that the role of these platforms as ecosystems is considered in the decommissioning process (Macreadie et al. 2012, Fowler et al. 2014, 2018, Bull and Love 2019, MeyerGutbrod et al. 2020). An ecological perspective of offshore platforms allows scientists to apply restoration principles to the decommissioning process, in a similar way to terrestrial restoration of abandoned mine sites (Koch and Hobbs 2007). The presence of offshore platforms modifies communities and habitats to such an extent that returning the site to its pre-installation state may no longer be feasible or preferable (Sommer et al. 2019) and as such, the benefits of in situ decommissioning must be evaluated. This assertion is congruent with the concept of novel ecosystems, which is intended to complement existing restoration practices. A novel ecosystem is one which has been altered by human activity and where restoration is not feasible or would result in the loss of ecosystem value (Hobbs et al. 2013). Recently there have been attempts to apply restoration management concepts to offshore platforms in terms of: establishing ecological baselines for restoring the ecosystem postdecommissioning (Fortune and Paterson 2020); the potential for restoration paradigms to shift the discourse surrounding RTR decommissioning (Ounanian et al. 56 Ch 3: Case study on the Wandoo field 2019); and direct application of novel ecosystems criteria to offshore platforms (Schläppy and Hobbs 2019, van Elden et al. 2019). There is still a significant knowledge gap around the ecology of these platforms, particularly outside of the major northern hemisphere oil and gas producing regions. In Australia, only a limited number of studies exist on the fish and shark communities around offshore infrastructure (Fowler and Booth 2012, Pradella et al. 2014, Bond et al. 2018a, 2018b, McLean et al. 2019, Thomson et al. 2021). Information on how ecological value is retained under varying decommissioning scenarios is needed at a time when the Australian government is reviewing legislation to potentially allow in situ decommissioning options (Offshore Resources Branch 2018, Taylor 2020). It is critical that we understand the ecological role platforms play in a regional context before the associated ecosystems are potentially lost due to decommissioning and restoration activity. The offshore oil and gas producing region of northwest Australia, the Northwest Shelf (NWS), is comprised of over 40 production facilities and over 2,000 km of subsea pipelines (Geoscience Australia 2009, Bond et al. 2018b). This is not a large number of platforms when compared with other locations around the world. However, the NWS is largely devoid of any significant natural hard substrate, and therefore offshore platforms contribute a significant portion of such habitat regionally, along with its associated fishes. This area was historically characterised by established macrobenthos communities made up of sponges, gorgonians and soft corals on flat, sand inundated pavement (Evans et al. 2014). These macrobenthos communities were largely removed by pair-trawling operations in the 1960s and 1970s (Sainsbury et al. 1997, Fromont et al. 2016). Previous studies on both platforms and pipelines on the NWS have found significant macrobenthos habitat associated with these structures, and abundance and richness of fish was higher on pipelines than on nearby natural habitats (Bond et al. 2018a, 2018b, McLean et al. 2018, 2019). These results suggest that the hard substrate provided by oil and gas infrastructure may modify the habitat and associated communities from their previously trawled state. 57 Ch 3: Case study on the Wandoo field We investigate whether the presence of active offshore infrastructure at a site on the NWS has resulted in the emergence of a novel ecosystem, characterised by a shift in the structure of marine communities. Demersal and pelagic taxonomic assemblages, as well as macrobenthos communities, were documented around the infrastructure in the Wandoo oil field (Wandoo) over three years and six surveys and in contrast to two control sites: a sandy site (Control Sand); and a natural reef (Control Reef). Baseline (pre-installation) ecological information for the Wandoo site was not collected, as has been the case for many older offshore platforms (Fortune and Paterson 2020). As such, the Control Sand site acts as a proxy for the historical state of the Wandoo site. We determined historical state as the state of the environment immediately prior to the installation of the Wandoo infrastructure, and as such, this site would have been subject to trawling. Anthropogenic disturbance creates challenges in selecting historical baselines, and our baseline selection is congruent with the Anthropocene baseline concept (Kopf et al. 2015). The Control Reef site is characterised by a rocky substrate with significant physical relief, and similar in spatial extent to the infrastructure in the Wandoo field. Control Reef provides contrast to the Wandoo site in the form of a natural reef that is comparable in in size (area) and depth (m). These two sites allowed us to both assess Wandoo as a novel ecosystem and predict how the marine communities would be altered under two different decommissioning scenarios. Specifically, complete removal may see the Wandoo site revert to a state more similar to the Control Sand site, and partial removal (topping) may lead to something more similar to the Control Reef site, due to the loss of the midwater hard substrate. We chose to use the post-trawling state of the Northwest Shelf as our historical baseline, as if the Wandoo infrastructure were to be removed, this area would likely be exposed to trawling again. We used baited remote underwater video systems (BRUVS) to determine how taxonomic richness, abundance, biomass, fork length, and community assemblage structure varied between these sites, as well as intra- and inter-annually. We hypothesise that the demersal and pelagic assemblages at Wandoo would more closely resemble those at the control reef site than those at the control sand site with respect to diversity, abundance and size. We then evaluated our findings on the Wandoo field against the criteria for testing 58 Ch 3: Case study on the Wandoo field whether an offshore platform can be classified as a novel ecosystem (van Elden et al. 2019). 3.3 MATERIALS AND METHODS Study sites The three sites sampled are located in the NWS region of northwest Australia, approximately 75 km northwest of Dampier, Western Australia (Fig. 3.1). The sites are all situated in waters approximately 50-60 m deep. The Wandoo site (WN) is an active oil field leased by Vermilion Oil and Gas Australia Pty Ltd (Vermilion). This site contains oil production infrastructure including: Wandoo A, an unmanned monopod wellhead platform with a 2.5 m diameter shaft supporting a helideck and production infrastructure; Wandoo B, a concrete gravity structure (CGS) made up of a 114 m long by 69 m wide caisson and four shafts, each 11 m in diameter, supporting the superstructure approximately 18 m above the sea surface; and a catenary anchored leg mooring (CALM) buoy, with six moorings and a Pipeline End Manifold (PLEM) below the buoy (Fig. 3.2). The infrastructure at the Wandoo site is surrounded by a 500 m exclusion zone, within which only authorised vessels are permitted to operate (Commonwealth of Australia 2010). These exclusion zones are in place around all offshore platforms in Australia, and represent some of the only areas on the Northwest Shelf fully protected from commercial fishing activity. Two control sites, comparable in depth to Wandoo, were also sampled: a flat sanddominated site, Control Sand (CS) comparable to the Wandoo site prior to infrastructure installation in 1994; and a reef site, Control Reef (CR) that is a natural structure comparable in dimension to the Wandoo infrastructure. The CS site is situated approximately 15 km northeast of the Wandoo site (Fig. 3.1) and is characterised by little to no physical relief and a dense, silty sand habitat. The CR site is located approximately 15 km west of the Wandoo site (Fig. 3.1) and is characterised by a rocky reef, similar in spatial extent to the infrastructure in the Wandoo field, rising to approximately 20 m below the surface. Unlike the WN site, the CS and CR sites are accessible to commercial and recreational fishing. 59 Ch 3: Case study on the Wandoo field Figure 3.1 Location of the three study sites, Wandoo, Control Reef and Control Sand, approximately 75 km north-west of Dampier, Western Australia Stereo-baited underwater video systems Stereo-BRUVS are a non-destructive, cost-effective method for studying marine fauna (Cappo et al. 2006, Letessier et al. 2013, 2015b). They have been used to study abundance, biomass, diversity, distribution and behaviour in animals ranging from fish and sharks, to turtles, moray eels, and marine mammals (Letessier et al. 2015a, Barley et al. 2016, Spaet et al. 2016, Whitmarsh et al. 2017, Thompson et al. 2019). Seabed stereo-BRUVS have been adapted to mid-water environments, making them a useful tool for documenting highly mobile and elusive species (Letessier et al. 2013, Bouchet et al. 2018, Thompson et al. 2019). BRUVS-derived data should be interpreted recognising the potential impact of variable bait plumes (Whitmarsh et al. 2017), the potential higher representation of piscivores, and the relative nature of abundance estimates in contrast with density estimates generated by, for instance, underwater visual census (UVC, Langlois et al., 2010). Despite these constraints, BRUVS can be used to document clear signals in marine communities relative to other methods (Cappo et al. 2006, Lowry et al. 2012). Seabed stereo-BRUVS consist of two GoPro cameras mounted 80 cm apart on a horizontal base bar, each converging at an angle of four degrees to a common focal 60 Ch 3: Case study on the Wandoo field point. A galvanised steel mesh bait cage containing 800 g of crushed pilchards is attached to the end of a 1.5 m long bait arm. Seabed stereo-BRUVS are deployed at least 200 m apart for a minimum of 60 minutes. Figure 3.4 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale Mid-water stereo-BRUVS consist of the same horizontal base bar as seabed stereoBRUVS, mounted on a 1.45 m long steel upright to provide stability, and suspended 10 m below the surface. They are baited with 1 kg of crushed pilchards in a perforated bait canister on a 1.5 m long bait arm, which acts as a rudder to keep the cameras facing down-current for the duration of the deployment. Mid-water stereo-BRUVS are deployed for a minimum of 120 minutes, and in this study, are anchored to prevent entanglement with subsea infrastructure. Data collection Sampling was undertaken over three years, from 2017-2019, with twice-yearly expeditions in the austral autumn and spring. Due to the significant tide range and variable weather conditions in the region, surveys were limited to a ten day window over neap tides. In most of the surveys, it was only possible to sample two of the three study sites, and the three sites were therefore not sampled evenly between 61 Ch 3: Case study on the Wandoo field years and seasons. The WN site was sampled in both autumn and spring in all three years. The CR site was sampled in autumn and spring of 2017, autumn of 2018 and spring of 2019, while the CS site was sampled in autumn and spring of 2018 and autumn of 2019. A total of 595 seabed stereo-BRUVS and 530 mid-water stereo-BRUVS deployments were conducted over the three year study period, using a random stratified sampling design. At the WN site, 14 sampling zones were established around the infrastructure, with seabed stereo-BRUVS deployed in ten zones around the structure, and mid-water stereo-BRUVS deployed nine zones. All stereo-BRUVS were deployed a minimum of 50 m away from any infrastructure at the Wandoo site so as to avoid collision and/or entanglement between the stereo-BRUVS and the infrastructure. To ensure consistency in data collection, stereo-BRUVS were deployed a minimum of 50 m away from the reef structure at the Control Reef site. All sampling was carried out during daylight hours to minimise the effect of crepuscular animal behaviour. The sampling was conducted under UWA ethics permit RA/3/100/1484. Data processing and treatment Prior to each survey, individual stereo-BRUVS were calibrated in an enclosed pool, according to standard protocols, using the CAL software (Harvey and Shortis 1998, SeaGIS Pty Ltd 2020). All video samples collected in the field were converted to AVI format using Xilisoft Video Converter Ultimate (Xilisoft Corporation 2016) and videos were processed using the Eventmeasure software package (SeaGIS Pty Ltd 2020). Processing commenced either once seabed stereo-BRUVS had settled on the seabed, for a period of 60 minutes, or when the mid-water stereo-BRUVS had stabilised at 10 m depth following deployment, for a period of 120 minutes. All animals entering the field of view were identified to the lowest possible taxonomic level, and abundance was estimated using the conservative abundance metric MaxN, which is the maximum number of individuals of a given taxon in a single frame (Cappo et al. 2006). The appropriate length metric (e.g. fork length FL, disc width DW, or carapace length CL) was measured in stereo with individuals measured where they were well positioned relative to the camera and not occluded 62 Ch 3: Case study on the Wandoo field by other individuals. For seabed stereo-BRUVS, the habitat visible in the field of view was broadly categorised into three groups: sand (bare substrate with no visible macrobenthos or other marine growth); sparse macrobenthos (predominantly bare substrate with less than 50% biotic cover); and dense macrobenthos (the visible substrate was dominated by more than 50% biotic cover). For seabed stereo-BRUVS, a sample was an individual rig deployment. For midwater stereo-BRUVS, samples consisted of each set of five BRUVS deployed in a zone. This method mitigates the potential effect of highly mobile pelagic species being observed on multiple midwater deployments. The video analysis yielded identification, abundance, and length data for each stereo-BRUVS deployment. These data were analysed as taxonomic richness (TR), total abundance (TA) and fork length (FL) respectively. Total biomass (TB) was calculated as the sum of mean weight of a given taxa on a given sample. Weight was calculated based on FL using taxon-specific length weight relationships (LWR) sourced from Fishbase (2019a). Where the LWR was not available for a particular taxon, the LWR based on total length (TL) for that taxon was used, in combination with taxon-specific TL:FL conversions. Where an animal was identified to genus or family, the Bayesian LWR was sourced from Fishbase (Froese et al. 2014). Taxonspecific biomass estimates were calculated by multiplying the abundance of each taxon by the mean weight of that taxon. Marine mammals were excluded from the biomass estimates as they were multiple orders of magnitude heavier than the largest observed fish and heavily skewed the estimates. These four univariate metrics, TR, TA, TB and FL, were analysed separately for each survey in order to ensure like-for-like comparisons between sites. Annual and seasonal variability were also assessed for each site to determine the variability in the demersal and pelagic communities at each site over time. These analyses were also carried out at the level of survey, comparing annual variability separately for autumn and spring at each site, and seasonal variability (i.e. between spring and autumn) for each year at each site. 63 Ch 3: Case study on the Wandoo field The prevalence of each taxa at each site was calculated by determining the percentage of seabed deployments or midwater zones on which the particular taxa was observed of the total for that site. The prevalence data were then used to determine the number of unique demersal and pelagic taxa for each site, by extracting taxa that were only recorded at one site. We did not count taxa which were recorded on only one midwater zone or seabed deployment per site, in order to eliminate chance sightings and possible incorrect identifications. Within the lists of unique taxa, any taxon that was only identified to genus or family was removed if there was a record from that genus or family at another site. Statistical analyses The categorised habitat data were analysed using a Chi-square contingency test to determine whether habitat varied significantly by site (Zar 1999). Variation in the fish assemblage was tested using PERMANOVA as it is robust to data heterogeneity (Anderson 2017). The linear variables of TA, TB and FL were log10 transformed to stabilise variance (Zar 1999). For each of these univariate measures, a Euclidean distance resemblance matrix was calculated and a PERMANOVA was applied based on unrestricted permutations (Anderson 2017) with Site and Survey as fixed factors. Site was defined as Wandoo, Control Reef or Control Sand, while Survey was defined as each of the six BRUVS surveys conducted in a particular season and year (e.g. Autumn 2017). Our main hypothesis was whether sites differed in their fish assemblages and the degree to which such differences varied temporally. To first determine whether sites differed, one-way pair-wise PERMANOVAs were applied within each survey period. We also similarly tested for differences between years and between seasons within sites. Repeated measures ANOVA was not used as the sampling through space and time varied randomly within the zones and seasons (Zar 1999). The assemblage composition data were treated differently to the univariate metrics. Species composition data were pooled across all surveys in preparation for the multivariate analyses for each sampling method. The data were analysed by survey to ensure like-for-like comparisons between sites. Multivariate analyses were completed on the pelagic and demersal taxonomic assemblage data in terms 64 Ch 3: Case study on the Wandoo field of abundance and biomass, to understand variations in species composition between sites as well as which variables explained this variation. We log(x+1) transformed the assemblage data and calculated Bray-Curtis resemblance matrices for abundance and biomass of each species. Pairwise PERMANOVAs were applied to determine the differences between the demersal and pelagic species compositions of the three sites, across all surveys, in terms of both abundance and biomass. Canonical analysis of principal coordinates (CAP) was used in order to visualise a constrained ordination of the data on the basis of distance or dissimilarity. A database of physical, chemical and biological variables was also compiled in order to understand the potential environmental effects on taxonomic assemblages. Distances to marine features (e.g. coral reefs and seamounts) were calculated using bathymetry data following Yesson et al. (2020). Environmental data were derived from the following datasets:  Geoscience Australia (GA) 250 m bathymetry (Whiteway 2009);  GA Australian submarine canyons (Huang et al. 2014);  CSIRO Atlas of Regional Seas (CARS) (Ridgway et al. 2002); and  Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS 2020) A number of anthropogenic variables, such as time to market and distance from nearest human population, were also calculated based on human accessibility calculations undertaken by Maire et al. (2016). However, the three sites are almost exactly the same distance from the coast, so distance-based variables were similar for all sites, and fishing effort data was not fine-scale enough to separate the three sites. As such, the anthropogenic variables were excluded. A Pearson’s correlation was run to identify highly correlated independent variables with a correlation coefficient >0.6 (Havlicek and Peterson 1976). Analyses included only one of any highly correlated variables in a given test. A distance‐based linear 65 Ch 3: Case study on the Wandoo field model (DistLM) was used to determine the relationship between these variables and the assemblage data across all surveys. All analyses were completed using the Primer 7 software package with the PERMANOVA + add-on (Anderson et al. 2015). 3.4 RESULTS In the six surveys across three years, we counted 35,070 individuals from 358 taxa, representing 85 families (Appendices 4 and 5). The total biomass of these animals was 42.5 tonnes, excluding marine mammals. Of the 358 taxa, 252 (70%) were unique to the demersal samples, 44 (13%) were unique to the pelagic samples, and 62 (17%) of the taxa were common to both sets of samples. Fork length of demersal taxa ranged from a 2 cm unidentified juvenile to a 260.4 cm wedgefish Rhynchobatus sp. Three families accounted for 57% of all demersal animals recorded: jacks (Carangidae; 32%), threadfin breams (Nemipteridae; 14%), and damselfishes (Pomacentridae; 11%), while the most prevalent demersal species was the starry triggerfish Abalistes stellatus, occurring on 91% of deployments. Pelagic taxa ranged in fork length from a 0.86 cm juvenile leatherjacket Monacanthidae sp., to a 6.27 m northern minke whale Balaenoptera acutorostrata, with the largest fish being a 3.93 m tiger shark Galeocerdo cuvier. Two families accounted for 79% of all pelagic animals recorded: herrings (Clupeidae; 40%) and jacks (Carangidae; 39%). The most prevalent pelagic taxon was scads Decapterus sp., occurring on 72% of deployments. Threatened species included two Critically Endangered taxa, wedgefishes Rhynchobatus sp. and great hammerhead Sphyrna mokarran, and two Endangered species, dusky shark Carcharhinus obscurus and zebra shark Stegostoma tigrinum (Dudgeon et al. 2019, Rigby et al. 2019a, 2019b). Environment Observed habitats across the three sites included sand, and macrobenthos which consisted of sponges, sea whips, crinoids, soft corals, and gorgonians. Macrobenthos coverage was both sparse (<50%) and dense (>50%). Habitat differed significantly across the three sites with the WN site characterised by a higher percentage of samples dominated by dense and sparse macrobenthos relative to the other two sites, (X2(2, N = 417) = 91.1, p < 0.001). Macrobenthos was 66 Ch 3: Case study on the Wandoo field present on 57% of the deployments at WN, with sand dominating deployments at CR and CS (60% and 99% respectively; Fig. 3.3). The highest percentage of dense macrobenthos also occurred at WN (22%), compared with 15% at CR and none at CS. Figure 3.7 Percentage habitat composition for each of the three sites. The habitat types are sand (yellow), sparse macrobenthos (light green) and dense macrobenthos (dark green). There was limited environmental variability between the sites (Appendix 3.1). As expected based on sampling design, depth was not significantly different between WN and CR (t468=1.87, p=0.06), although CS was significantly but only marginally deeper than WN and CR (t418=16.8, p< 0.001 and t298=7.87, p< 0.001 respectively). Mean sea surface temperature (SST) in autumn was similar at WN and CR (t 218=1.18, p=0.26), but was approximately one degree higher at CS than at WN and CR (t218=6.15, p<0.001 and t148=6.19, p<0.001 respectively; Appendix 3.1). Mean SST in spring did not differ significantly between WN and CS t 198=1.30, p=0.21), but was significantly higher at CR than at WN and CS (t 248=2.08, p=0.038 and t148=2.75, p=0.007 respectively). Mean chlorophyll concentration (Chl-a) in autumn was higher at WN than CR and CS (t218=3.34, p= 0.003 and t218=2.62, p=0.002 respectively), with no difference between the latter two sites (t 148=0.39, p=0.71). In spring, mean Chl-a was significantly higher at CR than both WN and CS (t248=7.84, p<0.001 and t148=4.55, p<0.001 respectively), with no significant difference between WN and CS (t198=1.21, p=0.22; Appendix 3.1). 67 Ch 3: Case study on the Wandoo field Demersal richness, abundance, biomass and fork length The mean demersal richness was 13.1 ±0.90 SE and ranged between 7.7 and 17.5 taxa per sample. There was significant variation in richness between sites in four of the six surveys, where richness was higher at WN than at the control site sampled in the same survey (Fig. 3.4a; Table 3.1) The only seasonal variation was in 2018 at WN, when richness was higher in autumn than spring, and the only annual variation was at CS, where richness was higher in 2018 than 2019 (Appendix 3.2). Abundance ranged from 17.9 to 77.4 individuals per sample, with a mean of 43.5 ±4.99 SE. Abundance was consistent between sites in most surveys, only differing in Autumn 2019 when abundance at WN was higher than at CS (Fig. 3.4b; Table 3.1). In terms of annual variability at WN, abundance in autumn was higher in both 2017 and 2018 than in 2019. In spring, abundance was also higher in 2017 than both 2018 and 2019. There was more annual variability in abundance at WN than at CR or CS, and seasonal abundance followed the same pattern at all sites, with abundance generally being higher in autumn than spring (Appendix 3.2). Mean biomass was 44.5 kg ±3.31 SE, and ranged from 28.2 kg to 70.2 kg per sample. Similarly to abundance, biomass was consistent between sites for all surveys except Autumn 2019, when biomass was higher at WN than CS (Fig. 3.4c; Table 3.1). The only annual variation was at CS, where biomass was higher in 2018 than 2019. Biomass was consistent between seasons at WN but was higher in autumn than spring at the control sites (Appendix 3.2). Fork length ranged from 24.8 cm to 38.5 cm per sample, with a mean of 32.6 cm ±1.05 SE. Fork length was consistent between sites in most surveys, but was higher at WN in Autumn 2017 and Autumn 2018 (Fig. 3.4d; Table 3.1). Fork length was generally higher in spring than autumn, and higher in 2019 at WN and CS (Appendix 3.2). Pelagic richness, abundance, biomass and fork length Mean pelagic richness was 3.9 ± 0.15 SE, with a range of 1.3 to 8.4 taxa per zone. Richness in the Autumn 2018 survey was significantly higher at WN and CS than at CR, but was consistent between sites in all other surveys (Fig. 3.4e; Table 3.1). Annual and seasonal richness was consistent in most surveys at both WN and CS, but there was significant annual and seasonal variation at CR (Appendix 3.3). 68 Ch 3: Case study on the Wandoo field Abundance ranged from 1.3 to 271 individuals per zone, with a mean of 29.6 ± 4.7 SE. Abundance was consistent between sites in four of the six surveys, and was higher at WN than at CR in the other two surveys (Fig. 3.4f; Table 3.1). Annual variability occurred at WN in spring, but at the control sites in Autumn, and there was seasonal variability in abundance at WN and CS (Appendix 3.3). Mean biomass was 48.5 kg ± 5.7 SE and ranged from 7.5 g to 429 kg per zone. Biomass was significantly lower at CR than CS in Autumn 2018, but was consistent between sites across all other surveys (Fig. 3.4g; Table 3.1). The only annual or seasonal variation in biomass was at CR, where biomass was higher in Autumn 2017 than Autumn 2018 (Appendix 3.3). Fork length ranged from 3.8 to 182 cm per zone, with a mean of 37.5 cm ± 3.3 SE. Fork length was higher in Autumn 2017 at WN than CR, and higher in Autumn 2018 at CS than WN. Fork length was consistent between sites in all other surveys (Fig. 3.4h; Table 3.2). There was no annual or seasonal variability in fork length at the control sites, with annual variability in three of the six surveys at WN (Appendix 3.3). Community assemblages There was strong separation of both demersal and pelagic taxonomic assemblages between sites, with abundance and biomass at each site characterised by unique species assemblages. Demersal and pelagic taxonomic assemblages were significantly different from each other at all sites, in terms of both abundance (Fig. 3.5) and biomass (Fig. 3.6) (Table 3.2). The DistLM analysis showed that the three environmental variables, depth, SST and Chl-a, did not explain a sufficient proportion of the variance in the assemblage data and as such, these analyses were excluded. Demersal abundance (Fig. 3.5a) and biomass (Fig. 3.6a) at WN were driven by reefassociated species, namely galloper Symphorus nematophorus and spot-cheek emperor Lethrinus rubrioperculatus. Both species usually occurred in low abundance but were prevalent across deployments at WN (38% and 40% respectively; Appendix 3.4). Abundance and biomass at CR were driven by different reef-associated species than at WN, namely bluespotted emperor Lethrinus punctulatus (the name most commonly used for this unresolved species; Moore et 69 Ch 3: Case study on the Wandoo field al., 2020) and turrum Carangoides fulvoguttatus, both of which occurred in large schools, while biomass was also driven by areolate grouper Epinephelus areolatus, a more solitary species. There was some overlap in taxonomic assemblages between WN and CR, driven by bluespotted tuskfish Choerodon cauteroma. Abundance at CS was characterised by northwest blowfish Lagocephalus sceleratus, a species associated with offshore reefs and sandy habitats, and brushtooth lizardfish Saurida undosquamis, a sand or mud bottom associated species. These species occurred in relatively low numbers but were highly prevalent on deployments at this site (51% and 80% respectively; Appendix 3.4). Brushtooth lizardfish also characterised biomass at CS, along with the milk shark Rhizoprionodon acutus, also associated with sandy habitats. Habitat associations were sourced from Fishbase (2019a). There were 17 demersal taxa from 11 families observed only at WN, compared with five unique taxa from five families at CR and four taxa from four families at CS (Table 3.3). Many of the demersal species unique to WN are reef-associated species, and WN was the only site where unidentified larval-stage juvenile fishes were present. Two demersal species recorded only at WN were observed on over 10% of deployments, namely the pickhandle barracuda Sphyraena jello, and giant sea catfish Netuma thalassina (Appendix 3.4). Pelagic assemblages followed similar patterns in terms of abundance (Fig. 3.5b) and biomass (Fig. 3.6b) to those observed in the demersal assemblages. Abundance and biomass at WN were driven by great barracuda Spyhraena barracuda and rainbow runner Elegatis bipinnulata. Great barracuda were usually solitary, but frequently observed at WN (60% of zones, Appendix 3.5), while rainbow runner were observed less frequently (15% of zones) but in large schools. There was some overlap in abundance between WN and CS, characterised by herrings (Clupeidae spp.) which were observed on 25% of zones at WN and 41% at CS. Abundance and biomass at CS was driven by silky sharks Carcharhinus falciformis and live sharksuckers Echeneis naucrates, and biomass was also characterised by cobia Rachycentron canadum. Abundance at CR was not strongly characterised by any particular species, while biomass was driven by great hammerheads Sphyrna mokarran, which was always solitary and only observed on 16% of zones. WN was the only site 70 Ch 3: Case study on the Wandoo field where any unique pelagic taxa were recorded, with rainbow runner not observed at either of the control sites (Table 3.3). 71 Ch 3: Case study on the Wandoo field Figure 3.10 Mean values with standard errors (SE) for taxonomic richness (TR), and logged values of total abundance (TA), total biomass (TB) fork length (FL) by survey for demersal (left) and pelagic (right) communities at the three sites: Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). 72 Table 3.1 Pairwise PERMANOVA tests comparing demersal and pelagic variation between sites for each survey, for taxonomic richness (TR), log total abundance (log10TA), log total biomass (log10TB) and log fork length (log10FL). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. Groups Control Reef, Wandoo Control Reef, Control Sand Control Reef, Wandoo Control Sand, Wandoo Control Sand, Wandoo Control Reef, Wandoo Control Sand, Wandoo Control Reef, Wandoo 58 59 48 71 62 71 66 76 1.94 4.24 0.13 6.99 5.82 2.14 4.09 0.33 0.059 (146) *0.001 (138) 0.885 (168) *0.001 (142) *0.001 (131) *0.029 (162) *0.001 (132) 0.742 (169) 0.88 0.97 0.07 1.31 5.04 1.80 1.07 1.76 0.393 (997) 0.341 (996) 0.936 (994) 0.176 (998) *0.001 (999) 0.082 (997) 0.298 (998) 0.079 (996) 1.91 1.37 1.86 0.34 2.78 1.61 1.21 0.07 0.063 (999) 0.175 (997) 0.063 (995) 0.721 (997) *0.004 (998) 0.114 (996) 0.226 (998) 0.939 (997) Control Reef, Wandoo Control Reef, Control Sand Control Reef, Wandoo Control Sand, Wandoo Control Sand, Wandoo Control Reef, Wandoo Control Sand, Wandoo Control Reef, Wandoo 16 12 12 16 9 16 16 16 1.43 4.93 4.10 0.48 2.06 1.44 0.84 1.49 0.194 (39) *0.003 (123) *0.003 (375) 0.65 (121) 0.089 (68) 0.182 (213) 0.419 (128) 0.179 (151) 2.59 3.65 3.47 0.31 0.74 0.03 0.38 0.40 *0.026 (981) *0.005 (805) *0.009 (768) 0.764 (981) 0.511 (312) 0.975 (972) 0.697 (974) 0.704 (910) 0.20 3.05 1.55 1.52 1.54 0.92 1.33 0.14 0.839 (976) *0.016 (779) 0.159 (775) 0.154 (975) 0.152 (318) 0.37 (974) 0.198 (974) 0.88 (981) p (perms) t log10TA p (perms) t log10TB p (perms) log10FL p (perms) t 3.29 2.17 3.39 2.27 1.42 0.81 1.09 0.65 3.14 1.04 0.94 2.21 0.75 0.54 0.58 0.83 *0.004 (996) *0.031 (997) *0.002 (997) *0.024 (996) 0.173 (999) 0.432 (998) 0.287 (996) 0.544 (998) *0.014 (978) 0.314 (762) 0.39 (775) *0.032 (977) 0.462 (315) 0.608 (976) 0.578 (976) 0.395 (984) Ch 3: Case study on the Wandoo field Survey x Site Demersal Autumn 2017 Autumn 2018 Autumn 2018 Autumn 2018 Autumn 2019 Spring 2017 Spring 2018 Spring 2019 Pelagic Autumn 2017 Autumn 2018 Autumn 2018 Autumn 2018 Autumn 2019 Spring 2017 Spring 2018 Spring 2019 TR d.f. t 73 Ch 3: Case study on the Wandoo field Table 3.2 Pairwise PERMANOVA results comparing abundance and biomass of the pelagic and demersal taxonomic assemblages between sites: Wandoo (WN); Control Sand (CS); and Control Reef (CR). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. Abundance Demersal Pelagic Groups CR, CS CR, WN CS, WN CR, CS CR, WN CS, WN Biomass t (d.f.) 4.46 (218) 3.48 (329) 6.76 (317) 1.86 (52) 1.88 (82) 2.30 (72) p(perms) *0.001 (998) *0.001 (996) *0.001 (999) *0.002 (999) *0.001 (998) *0.001 (999) Groups CR, CS CR, WN CS, WN CR, CS CR, WN CS, WN t (d.f.) 4.85 (218) 3.53 (329) 7.53 (317) 1.63 (52) 2.20 (82) 2.44 (72) p(perm) *0.001 (999) *0.001 (998) *0.001 (997) *0.013 (998) *0.001 (999) *0.001 (999) 74 Ch 3: Case study on the Wandoo field Figure 3.13 Canonical analysis of principal coordinates (CAP) for abundance of (a) demersal and (b) pelagic taxonomic assemblages at Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). Species clockwise from top in (a) are: bluespotted emperor Lethrinus punctulatus, northwest blowfish Lagocephalus sceleratus, brushtooth lizardfish Saurida undosquamis, galloper Symphorus nematophorus, spot-cheek emperor Lethrinus rubrioperculatus, bluespotted tuskfish Choerodon cauteroma, and turrum Carangoides fulvoguttatus. Taxa clockwise from top in (b) are: live sharksucker Echeneis naucrates, scads Decapterus sp., silky shark Carcharhinus falciformis, herrings Clupeidae sp., great barracuda Sphyraena barracuda, and rainbow runner Elegatis bipinnulata. Images © R. Swainston/anima.fish Figurer 3.6 Canonical analysis of principal coordinates (CAP) for biomass of (a) demersal and (b) pelagic taxonomic assemblages at Wandoo (green); Control Reef (dark blue) and Control Sand 75 Ch 3: Case study on the Wandoo field Figurer 3.6 Canonical analysis of principal coordinates (CAP) for biomass of (a) demersal and (b) pelagic taxonomic assemblages at Wandoo (green); Control Reef (dark blue) and Control Sand (light blue). Species clockwise from top in (a) are: bluespotted emperor Lethrinus punctulatus, milk shark Rhizoprionodon acutus, brushtooth lizardfish Saurida undosquamis, galloper Symphorus nematophorus, spot-cheek emperor Lethrinus rubrioperculatus, bluespotted tuskfish Choerodon cauteroma, turrum Carangoides fulvoguttatus, and areolate grouper Epinephelus areolatus. Taxa clockwise from top in (b) are: great hammerhead Sphyrna mokarran, live sharksucker Echeneis naucrates, cobia Rachycentron canadum, silky shark Carcharhinus falciformis, rainbow runner Elegatis bipinnulata, and great barracuda Sphyraena barracuda. Images © R. Swainston/anima.fish 76 Table 3.3 Abundance, biomass and prevalence of taxa observed at a single site at WN (16 demersal and 1 pelagic species), CR (5 demersal and 0 pelagic species) and CS (4 demersal and 0 pelagic species), based on demersal and pelagic sampling records. Species marked with an asterisk are commonly caught commercially and/or recreationally in the North Coast Bioregion (Rome and Newman, 2010). Binomial Common names Apogonidae sp. Netuma thalassina Meiacanthus sp. Carangoides dinema Carangoides orthogrammus Caranx sexfasciatus Caranx tille* Nebrius ferrugineus Juvenile sp. Gymnocranius euanus Parapercis sp. Pomacentrus nagasakiensis Cephalopholis sonnerati* Epinephelus chlorostigma* Epinephelus malabaricus* Sphyraena jello cardinalfishes giant sea catfish combtooth blennies shadow trevally island trevally bigeye trevally tille trevally tawny nurse shark unidentified juvenile paddletail seabream grubfishes blue-scribbled damsel tomato rockcod brownspotted grouper Malabar grouper pickhandle barracuda Abundance Biomass (g) 41 2 2 2 1 4 1 1 1 1 1 3 2 1 1 2 37.65 4696.20 22.33 1435.95 1308.26 12604.88 4334.75 5064.06 0.05 554.72 18.09 6.68 978.65 1024.97 4097.69 7637.25 Prevalence (%) 1.4 12.1 0.9 0.9 2.3 1.4 0.9 2.3 0.9 1.4 2.3 0.9 0.9 0.9 1.9 10.7 77 Ch 3: Case study on the Wandoo field Family Demersal Wandoo Apogonidae Ariidae Blenniidae Carangidae Carangidae Carangidae Carangidae Ginglymostomatidae Juvenile Lethrinidae Pinguipedidae Pomacentridae Serranidae Serranidae Serranidae Sphyraenidae Table 3.3 (cont.) Demersal Control Reef Control Sand Pelagic Wandoo Family Binomial Common name Chaetodontidae Labridae Lethrinidae Monacanthidae Muraenidae Carangidae Clupeidae Congridae Lutjanidae Chaetodon auriga Bodianus bilunulatus Lethrinus atkinsoni* Eubalichthys caeruleoguttatus Gymnothorax undulatus Seriola rivoliana* Clupeidae sp. Gorgasia sp. Pristipomoides multidens* threadfin butterflyfish saddleback pigfish yellowtail emperor bluespotted leatherjacket undulated moray highfin amberjack herrings garden eels goldband snapper 2 1 2 1 1 11 334 31 1 445.78 439.87 1265.86 822.73 0.97 3280.25 22240.67 2525.02 3498.20 1.7 2.6 2.6 1.7 1.7 1.9 1.9 2.9 1.9 Carangidae Elagatis bipinnulata rainbow runner 22 112861.56 15.0 Abundance Biomass (g) Prevalence (%) Ch 3: Case study on the Wandoo field 78 Ch 3: Case study on the Wandoo field 3.5 DISCUSSION The demersal and pelagic community assemblages in the Wandoo field are distinct from those that would have existed prior to the installation of the infrastructure. The habitat around Wandoo is dominated by macrobenthos, in contrast with the sanddominated habitat that would have likely prevailed historically (Sainsbury et al. 1993). As a result, the Wandoo demersal assemblage is characterised by reef-associated rather than sand-associated taxa. The pelagic assemblage at Wandoo is different from the other two sites, driven by species associated with offshore platforms on the NWS as well as in other regions around the world (Friedlander et al. 2014, Reynolds et al. 2018, McLean et al. 2019). Overall, the demersal and pelagic assemblages more closely resemble a natural reef than the assemblages that would have existed pre-installation, which is congruent with our hypothesis. However, the composition of these assemblages is still unique to Wandoo, suggesting the emergence of a novel ecosystem. While the focus of our study was on the fish assemblages, we saw clear differences in the habitat at the three sites. The proliferation of macrobenthos at the otherwise flat WN site, in contrast to the barren sand habitat at CS, likely reflects the exclusion of seabed trawling at WN. The WN site also had higher demersal fish richness than the control sites in most surveys which suggests that habitat composition is a driver of diversity in these demersal communities, as has been found elsewhere on the NWS (2019b). The Pilbara Offshore meso-scale region, within which the study sites are located, is a biodiversity hotspot for sponges (Fromont et al. 2016). However, as much of the macrobenthos biomass was removed by seabed trawling (Sainsbury et al. 1993), most of the habitat in this region has been simplified. The impact of trawling is clear at CS and the area surrounding the reef at CR, with both sites dominated by bare sand. In contrast, WN excludes seabed trawling up to 500 m from the infrastructure, and exhibited similar macrobenthos communities to other oil and gas infrastructure on the NWS (Bond et al. 2018a, McLean et al. 2019). The demersal community at WN was more diverse and reef-associated than the communities at the control sites. The higher demersal richness at WN is congruent with studies from Brazil, the Persian Gulf and Gabon, which describe offshore platforms as diversity hotspots (Friedlander et al. 2014, Fonseca et al. 2017, Torquato 79 Ch 3: Case study on the Wandoo field et al. 2017). High diversity is often associated with structural complexity of hard substrate (Friedlander and Parrish 1998), and this association was observed in ROV surveys of the Wandoo infrastructure (Tothill 2019). This study sampled areas around the infrastructure with little to no hard substrate, suggesting a large area of influence or “ecological halo” around the Wandoo infrastructure. The species that characterised the demersal taxonomic assemblage at WN, namely galloper and spot-cheek emperor, are both valued as fishing species: galloper is a prized sport fish, while spot-cheek emperor is a food fish targeted by recreational and commercial fishers (Rome and Newman 2010, 2019a). These species occupy different habitats, with galloper inhabiting coral reefs and spot-cheek emperor inhabiting sand/rubble areas (2019a). Spot-cheek emperor was rarely observed at either control site, despite the habitat at CR arguably being more suitable than that found at WN. Fishing activity, which is excluded at WN, may be the reason for the lower prevalence of this species at the control sites. The similarity in pelagic communities across sites in terms of all four metrics was expected, given the three sites are located relatively close to each other and the highly mobile nature of pelagic species. For example, great barracuda have been shown to travel 12 km in a day and can migrate over 100 km, while silky sharks can travel up to 60 km a day (Bonfil 2008, O’Toole et al. 2011). While these species are highly mobile, there was still strong distinction in the taxonomic assemblages between the three sites. The two species which characterised the taxonomic assemblage at WN, great barracuda and rainbow runner, are often associated with offshore platforms. Great barracuda is a commonly recorded species around offshore platforms in the Gulf of Mexico (e.g. Reynolds et al. 2018; Wetz et al. 2020), accounted for 33.2% of the biomass at offshore platforms in Gabon (Friedlander et al. 2014), and was recorded in 100% of remotely operated vehicle (ROV) transects at another platform on the NWS (McLean et al. 2019). Rainbow runner have also been recorded around platforms in the Gulf of Mexico, Gabon, and Brunei (Chou et al. 1992, Friedlander et al. 2014, Reynolds et al. 2018). Great hammerheads characterised biomass at CR, which was attributed to the fact that these are large animals and would have a significant effect on biomass even if present in low numbers, especially as there was not a particularly high abundance of any other species at this site. The pelagic taxonomic assemblage at 80 Ch 3: Case study on the Wandoo field CS was characterised by silky sharks, which were observed within minutes of the vessel’s arrival to conduct surveys at this site. This behaviour, and the associated high abundance and biomass of this species, were attributed to the frequent commercial fishing activity that occurs at this site. There are commercial line, trap and trawl fisheries operating throughout this area, including CS and, to a lesser extent, CR (WAFIC 2020). This population of silky sharks is thought to be opportunistically targeting the discards from the commercial fishing vessels as a food source, which would explain their high abundance at a site otherwise scarce in the typical prey of this species, which includes scombrids, carangids, snappers and groupers (Compagno 1984). A distinct marine community exists at WN with various taxa not observed at natural habitats. Many of the 17 unique demersal species at WN are reef-associated, but species such as paddletail seabream Gymnocranius euanus and blue-scribbled damsel Pomacentrus nagasakiensis are found in sandy areas adjacent to reefs (2019a). This suggests that the combination of sand and macrobenthos habitats around WN, itself a de facto artificial reef, is a key component of the high diversity and unique assemblage at this site. Reef-associated species tend to have strong site fidelity and postsettlement ranges of less than 50 m (Frederick 1997). While it is possible that some species recruit to WN from natural sites, and certainly would have done when the platform was first installed, the high number of species unique to WN suggests that fish are being produced at the platform, rather than simply being attracted from natural habitats. Tothill (2019) observed juvenile fishes in the midwater (10-22 m) sections of Wandoo, providing further evidence of fish production. There was only one pelagic species unique to a single site, which may reflect the relatively mobile nature of pelagic animals. Rainbow runner were only observed at the WN site, which could be attributed to the association of this species with offshore platforms around the world (Chou et al. 1992, Reynolds et al. 2018). Offshore platforms can function as fish aggregation devices (FADs), aggregating fish by facilitating foraging and school formation (Dagorn et al. 2000, Haugen and Papastamatiou 2019). Rainbow runner are thought to primarily aggregate around FADs to prey on small FAD-associated pelagic fishes (Xuefang et al. 2013), and it is possible that the vertical hard structure at WN is providing enhanced foraging opportunity for this species. 81 Ch 3: Case study on the Wandoo field The exclusion of fishing around WN has created a de facto MPA, as has been reported at other offshore platforms (Love et al. 2006, Friedlander et al. 2014, Fujii and Jamieson 2016). Seabed trawling on the NWS in the 1970s not only removed much of the macrobenthos habitat, but also resulted in a significant shift in fish composition (Sainsbury et al. 1993). The trawl catch shifted from being dominated by emperors (Lethrinus sp.) and snappers (Lutjanus sp.), to being dominated by lizardfish (Saurida sp.) and threadfin bream (Nemipterus sp.), with the abundance of lizardfishes greater by an order of magnitude (Thresher et al. 1986, Sainsbury et al. 1993). This relationship between habitat and species composition was also observed in this study: macrobenthos habitat was present at WN and CR, both of which were characterised by emperors. In contrast, at CS the habitat was almost completely devoid of macrobenthos, and the species composition was characterised by brushtooth lizardfish. Lizardfishes feed on benthic fishes, particularly on juveniles of other species, and are estimated to collectively consume 4 x 107 fishes per day on the NWS (Thresher et al. 1986). Demersal communities dominated by lizardfish, such as CS, would therefore have been significantly impacted by the proliferation of this genus. The de facto MPA has also resulted in a large ecological halo around the WN infrastructure. The ecological halo around offshore platforms and artificial reefs is usually around 1534 m, with abundance and diversity similar to natural habitats beyond this distance (Stanley and Wilson 1996, Scarcella et al. 2011, Reeds et al. 2018). In contrast, diversity at WN was higher than natural habitats at more than 50 m from the infrastructure. It is likely that the larger ecological halo at WN is due to the 500 m exclusion zone which was not present around the infrastructure in other ecological halo studies. The WN ecological halo is driven by recovery of macrobenthos habitat due to the exclusion of trawling activity. Wandoo as a novel ecosystem The ecosystem in the Wandoo field clearly has novel attributes when compared with natural systems in the region; however this assertion is not, on its own, sufficient to warrant labelling Wandoo a novel ecosystem. Van Elden et al. (2019) used the novel ecosystems definition developed by Hobbs et al (2013) to establish three criteria for evaluating offshore platforms as novel ecosystems: 82 Ch 3: Case study on the Wandoo field The abiotic, biotic and social components of the system differ from those that prevailed historically. The addition of hard substrate through the installation of the Wandoo infrastructure altered the abiotic component of the system. It is impossible to quantify the historical baseline of the biotic component, however the findings of this study show that the biotic components of the Wandoo ecosystem, in terms of habitat and marine communities, are distinct from those found at a proxy of their preinstallation (post-trawling) historical state, i.e. the Control Sand site. The major social driver of this ecosystem is the exclusion of fishing activity, which has been detrimental to large areas of the NWS. The de facto MPA effect of Wandoo has been particularly important in providing a refuge for fishes and allowing macrobenthos communities to recover. The ecosystems have a tendency to self-organize and manifest novel qualities without intensive human management. The Wandoo ecosystem, like those found at most other offshore platforms, is an unintended consequence of the installation of the platform and therefore is not subject to any human management. The only management undertaken is cleaning of sections of the subsea structure, but this activity only removes a small portion of the marine growth. The factors that allow this ecosystem to thrive, such as the exclusion of fishing and the provision of hard substrate, are artefacts of the presence of the platform. Novel ecosystems are prevented from returning to their historical states by practical limitations, in the form of ecological, environmental and social considerations. Wandoo is due to remain operational for at least a further ten years, which is a significant social consideration as the presence of the infrastructure is central to this ecosystem. When Wandoo is decommissioned, it is possible that complete removal will allow the ecosystem to return to its pre-installation state due to exposure to trawling, but the evidence presented here on the unique ecology of Wandoo should provide an ecological consideration against complete removal, thereby preventing a return to the historical state of the site. Based on these criteria, Wandoo may be classified as a novel ecosystem. The environment and ecology of the site have been altered, a self-organising ecosystem 83 Ch 3: Case study on the Wandoo field with novel qualities has emerged, and the presence of the platform prevents the ecosystem from returning to its post-trawling state. Implications for decommissioning We have used proxies for different decommissioning scenarios, which can provide a broad idea of how the Wandoo ecosystem might look post-decommissioning. We suggest that the Control Sand site is a proxy for complete removal, as this site is already a proxy for the Wandoo site without infrastructure. If the Wandoo infrastructure was completely removed, there would be a significant loss in diversity, particularly in terms of reef-associated species. Pelagic species associated with midwater structure, such as great barracuda and rainbow runner, are also likely to no longer be present at this site. Commercial and recreational fishing activity would likely recommence in the field post-decommissioning, as the petroleum safety zone would no longer be in effect and there would be no significant hard structure to prevent seabed trawling. Topping, a second decommissioning scenario, would result in partial removal of Wandoo down to around 25 m below the surface. This method has been applied to shallow-water platforms in the U.S. (Ajemian et al. 2015). The reef at the Control Reef site rises to around 30 m below the surface, making this a close approximation to a topped Wandoo. This scenario would also result in the loss of pelagic species associated with structure, but would result in the retention of more of the demersal community than complete removal. There would be some losses: the shallower portions of Wandoo are important for juveniles, exhibit higher richness and abundance than deeper portions and are characterised by small reef fish such as damselfishes (Tothill 2019). Indeed larval-stage juveniles were absent from the Control Reef site, and abundance of small demersal species such as damselfishes was generally lower than at the Wandoo site. It is likely that even under a topping scenario there would no longer be any exclusion of fishing activity around the remaining part of the platform. Seabed trawling could still occur in the areas surrounding the infrastructure that were previously protected by the petroleum safety zone. Partial or complete removal of the Wandoo platform will likely have adverse impacts on a number of taxa and alter the role of the infrastructure as a novel ecosystem, 84 Ch 3: Case study on the Wandoo field specifically in terms of the artificial reef and associated ecological halo. Partial removal would be less detrimental in that it would also still afford protection to the macrobenthos from seabed trawling. However there is significant ecological benefit in retaining the midwater sections of the infrastructure, for both pelagic species and juvenile reef-associated species, and leaving the platform standing in place would maintain these benefits. Additional aspects that should also be considered include the role of the infrastructure for seabirds, marine megafauna and macrobenthos communities attached to the infrastructure, as have been reported from other offshore platforms around the world (Ronconi et al. 2015, Bond et al. 2018b, Todd et al. 2019, Thomson et al. 2021). The exclusion of fishing is a critical component of the large ecological halo present at Wandoo, however the petroleum safety zone would like cease to exist post-decommissioning. We would recommend that postdecommissioning protection from fishing, in the form of a no-take MPA, should be considered. The installation of infrastructure in the Wandoo field has resulted in the emergence of a novel ecosystem with distinct ecological characteristics not found at natural sites in the region. The demersal and pelagic communities more closely resemble reef communities than those present pre-installation, but are still unique from those found at natural habitats in the region. The novel ecosystem at Wandoo also acts as a refuge for these communities, functioning as a de facto MPA in a region impacted by historical and current fishing activity. This MPA not only protects fish communities, but has allowed the macrobenthos to recover from the impacts of seabed trawling. Many of the novel characteristics of the Wandoo ecosystem would be lost under decommissioning scenarios that involve partial or complete removal, and the impact of decommissioning on fauna such as seabirds is still unknown. Recognising the Wandoo field as a novel ecosystem provides a mechanism for recognising the ecological role played by the Wandoo infrastructure, and underlines the need to consider the ecological role of each offshore platform prior to decommissioning. 3.6 STATEMENTS Data Accessibility: Survey data can be accessed through the FishBase BRUVS portal (https://bit.ly/3AILCl0). 85 Ch 3: Case study on the Wandoo field Competing interests: This project is funded by Vermilion Oil and Gas Australia (VOGA). VOGA has 100% operating interest in the Wandoo field where this work was conducted. VOGA did not participate in the design of the study, analysis of the data, or development of the manuscript. Author contributions: SVE conceived the study with input from JJM and RJH. SVE wrote the first draft, and revised and submitted the manuscript with revisions from JJM and RJH. All authors approved the final version of the manuscript. 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Report for the Director of National Parks. 92 3.8 APPENDICES Appendix 3.1 Environmental data for each survey used in the DistLM analyses, including start and end dates, depth, sea surface temperature (SST), and chlorophyll concentration (Chl-a). Data were derived from: Geoscience Australia 250 m bathymetry (Whiteway, 2009) and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020). The sites are: Wandoo (WN); Control Reef (CR); and Control Sand (CS). Survey Autumn 2017 Autumn 2018 Autumn 2019 4/05/2017 19/04/2018 25/04/2019 28/09/2017 End Date Site 9/05/2017 CR 26/04/2018 30/04/2019 3/09/2018 7/09/2019 Min Max Mean ± SD Min Max Mean ± SD Min Max Mean ± SD 57.6 53.2 ± 2.02 27.8 27.9 27.9 ± 0.03 0.42 0.47 0.46 ± 0.02 WN 48.9 55.2 52.4 1.64 27.9 28.0 28 0.02 0.36 0.49 0.4 0.04 CR 47.3 56.7 53 2.5 30.5 30.6 30.6 0.07 0.15 0.17 0.17 0.01 CS 53.1 56.7 54.8 0.78 30.5 30.7 30.6 0.1 0.16 0.19 0.19 0.01 WN 50.3 55.7 52.5 1.39 30.4 30.6 30.5 0.07 0.17 0.19 0.19 0.01 CS 53.0 55.0 54.1 0.63 28.6 28.6 28.7 0.01 0.69 0.79 0.75 0.04 WN 50.0 55.0 52.9 1.31 28.4 28.6 28.5 0.04 0.75 0.96 0.89 0.06 43.1 56.6 52.7 2.99 24.9 25.0 25 0.04 0.61 0.66 0.64 0.02 49.3 57.5 52.4 1.39 24.8 24.9 24.9 0.02 0.38 0.42 0.41 0.01 53.3 57.2 55.3 1.19 23.7 23.8 23.8 0.02 0.30 0.31 0.31 0.01 50.2 56.7 52.7 1.5 23.5 23.5 23.6 0.02 0.21 0.23 0.23 0.01 43.0 56.0 52.6 2.99 23.2 23.3 23.3 0.03 0.23 0.25 0.24 0.01 50.0 54.0 52.3 1.17 23.2 23.3 23.3 0.03 0.23 0.34 0.26 0.04 4/10/2017 CR 19/09/2018 CS WN Spring 2019 Chl-a (mg/m3) 48.1 WN Spring 2018 SST (°C) 11/09/2019 CR WN 93 Ch 3: Case study on the Wandoo field Spring 2017 Start Date Depth (m) Appendix 3.2 Pairwise PERMANOVA comparing demersal variation between years for autumn and spring at each site for taxonomic richness (TR), log total abundance (log10TA), log total biomass (log10TB) and log fork length (log10FL). Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. Autumn Wandoo Spring Seasonal Control Reef Control Sand Autumn Spring Seasonal Autumn Seasonal Groups d.f. t 2017, 2018 63 0.502 2017, 2019 71 0.679 2018, 2019 68 1.24 2017, 2018 66 1.335 2017, 2019 78 2.014 2018, 2019 72 0.633 2017 69 0.216 2018 60 2.13 2019 80 1.86 2017, 2018 43 1.498 2017, 2019 69 0.449 2017 60 0.343 2018, 2019 65 2.58 2018 77 0.947 TR p(perms) 0.601 (161) 0.496 (150) 0.226 (147) 0.179 (159) 0.058 (190) 0.538 (161) 0.837 (168) *0.041 (82) 0.053 (163) 0.149 (160) 0.672 (151) 0.767 (131) *0.013 (50) 0.34 (74) t 0.256 3.725 3.312 2.268 3.53 1.206 0.792 3.72 3.009 0.256 0.123 2.44 3.118 3.72 log10TA p(perms) 0.805 (999) *0.001 (997) *0.004 (997) *0.020 (996) *0.001 (997) 0.211 (996) 0.436 (996) *0.002 (995) *0.002 (997) 0.805 (999) 0.891 (998) *0.012 (997) *0.003 (996) *0.001 (995) t 1.479 1.01 0.859 1.706 1.462 0.367 0.568 1.255 1.718 1.262 0.154 4.344 2.054 3.058 log10TB log10FL p(perms) t p(perms) 0.133 (995) 0.145 0.875 (992) 0.307 (999) 4.908 *0.001 (997) 0.394 (999) 4.685 *0.001 (998) 0.089 (995) 0.053 0.958 (998) 0.124 (998) 2.687 *0.009 (997) 0.719 (997) 3.07 *0.004 (995) 0.578 (995) 2.204 *0.021 (997) 0.218 (995) 2.356 *0.019 (997) 0.112 (998) 1.265 0.222 (998) 0.224 (996) 0.547 0.631 (999) 0.876 (996) 2.256 *0.024 (997) *0.001 (998) 0.236 0.825 (996) *0.035 (997) 4.392 *0.001 (997) *0.003 (992) 2.143 *0.034 (997) Ch 3: Case study on the Wandoo field 94 Appendix 3.3 Pairwise permanova comparing pelagic variation between years for autumn and spring at each site, in terms of taxonomic richness (TR), log total abundance (log10TA), log total biomass (log10TB) and log fork length (log10FL. Degrees of freedom (d.f.) are reported. P-values in bold and with an asterisk are < 0.05, and the number of permutations (perms) are reported in parentheses. Autumn Wandoo Spring Seasonal Control Reef Control Sand Autumn Spring Seasonal Autumn Seasonal Groups d.f. 2017, 2018 16 2017, 2019 14 2018, 2019 14 2017, 2018 16 2017, 2019 16 2018, 2019 16 2017 16 2018 16 2019 14 2017, 2018 12 2017, 2019 16 2017 16 2018, 2019 11 2018 16 TR t p(perms) 0.518 0.615 (130) 1.257 0.234 (62) 0.592 0.618 (212) 1.167 0.265 (218) 0.452 0.677 (144) 1.398 0.179 (125) 4.49 *0.002 (262) 1.534 0.149 (275) 3.376 0.008 (146) 6.83 *0.001 (170) 2.483 *0.030 (230) 6.932 *0.001 (393) 1.959 0.066 (83) 0.663 0.525 (64) log10TA t p(perms) 1.476 0.161 (978) 0.452 0.661 (952) 1.843 0.092 (943) 3.397 *0.003 (973) 0.741 0.462 (957) 3.718 *0.001 (966) 4.621 *0.001 (975) 0.548 0.583 (981) 5.363 *0.001 (942) 4.212 *0.002 (787) 0.319 0.742 (961) 5.712 *0.001 (977) 0.627 0.528 (554) 0.993 0.339 (980) log10TB t p(perms) 0.38079 0.689 (982) 0.96021 0.349 (958) 1.1664 0.281 (962) 0.13979 0.892 (974) 1.8217 0.1 (972) 1.3543 0.192 (971) 0.45032 0.651 (980) 0.81364 0.455 (980) 1.0773 0.252 (963) 4.0458 *0.001 (804) 2.081 0.052 (980) 0.75851 0.462 (983) 0.58776 0.591 (533) 0.34781 0.722 (983) log10FL t p(perms) 2.983 *0.007 (977) 0.028 0.98 (951) 2.14 0.063 (952) 1.147 0.256 (975) 4.45 *0.001 (973) 3.831 *0.003 (967) 2.064 0.059 (973) 1.507 0.181 (987) 5.734 *0.001 (955) 1.016 0.319 (802) 2.054 0.053 (975) 1.729 0.09 (978) 1.303 0.226 (543) 1.123 0.279 (973) Ch 3: Case study on the Wandoo field 95 Ch 3: Case study on the Wandoo field Appendix 3.4 Prevalence (%) of demersal species recorded at WN, CR and CS. Prevalence refers to the number of deployments on which a taxon was observed, out of the total number of deployments at that site. Binomial Abalistes stellatus Acanthocybium solandri Acanthurus auranticavus Acanthurus blochii Acanthurus grammoptilus Acanthurus sp. Acanthurus xanthopterus Aetobatus ocellatus Aipysurus laevis Aipysurus sp. Alectis ciliaris Alectis indica Alepes vari Aluterus monoceros Aluterus scriptus Amblyeleotris sp. Amblygobius phalaena Apogonidae sp. Apolemichthys trimaculatus Aprion virescens Argyrops bleekeri Argyrops spinifer Arothron sp. Arothron stellatus Aspidontus dussumieri Aspidontus taeniatus Asteroidea sp. Asteroidea sp. Atule mate Balistidae sp. Blenniidae sp. Bodianus bilunulatus Bodianus perditio Bodianus solatus Bodianus sp. Bothus pantherinus Bothus sp. Brachyura sp. Caesionidae sp. Canthigaster sp. Carangidae sp. Carangoides armatus Carangoides chrysophrys WN 92.1 0.5 2.8 0.9 1.9 3.3 0.9 0.9 0.9 0.5 1.4 0.5 0.5 0.5 1.4 0.5 0.9 37.7 0.5 1.9 0.9 1.4 0.5 0.9 10.2 0.5 0.9 0.5 2.8 0.5 0.5 0.5 8.4 32.6 CR 95.7 6.0 0.9 6.0 0.9 0.9 5.2 0.9 0.9 3.4 0.9 24.1 0.9 1.7 0.9 5.2 0.9 0.9 1.7 0.9 2.6 16.4 2.6 12.1 13.8 CS 84.6 1.0 1.0 1.0 3.8 1.0 5.8 1.0 1.0 4.8 1.9 27.9 1.0 13.5 Binomial Carangoides coeruleopinnatus Carangoides dinema Carangoides fulvoguttatus Carangoides gymnostethus Carangoides oblongus Carangoides orthogrammus Carangoides sp. Caranx ignobilis Caranx melampygus Caranx papuensis Caranx sexfasciatus Caranx sp. Caranx tille Carcharhinidae sp. Carcharhinus amblyrhynchos Carcharhinus amboinensis Carcharhinus falciformis Carcharhinus leucas Carcharhinus limbatus Carcharhinus melanopterus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sorrah Carcharhinus sp. Caretta caretta Cephalopholis boenak Cephalopholis sonnerati Cephalopholis sp. Chaetodon auriga Chaetodon lineolatus Chaetodontidae sp. Chaetodontoplus duboulayi Chaetodontoplus personifer Chaetodontoplus sp. Chelmon marginalis Chiloscyllium punctatum Chlorurus sp. Choerodon cauteroma Choerodon schoenleinii Choerodon vitta Chromis fumea Chromis sp. Chromis westaustralis WN CR CS 69.8 0.9 58.6 47.4 0.5 2.3 7.4 2.8 0.5 1.4 1.4 0.9 0.9 0.5 43.1 57.8 61.2 3.4 2.6 2.6 - 17.3 4.8 50.0 15.4 2.9 - 5.1 1.4 0.5 0.5 0.5 1.4 2.8 0.5 0.9 1.9 23.7 24.2 0.5 1.4 0.5 47.0 0.5 21.4 0.5 0.5 1.7 0.9 0.9 0.9 6.0 0.9 1.7 0.9 0.9 15.5 15.5 1.7 0.9 0.9 44.8 1.7 0.9 11.2 0.9 - 1.0 1.0 1.9 3.8 1.0 10.6 1.0 1.0 1.0 1.9 1.0 - 96 Ch 3: Case study on the Wandoo field Binomial Chrysiptera tricincta Cirrhibarbis sp. Cirrhilabrus sp. Cirrhitidae sp. Clupeidae sp. Congrogadus sp. Coradion altivelis Coradion chrysozonus Coradion sp. Coris caudimacula Coris pictoides Coris sp. Crinoidea sp. Cromileptes altivelis Dasyatidae sp. Decapterus sp. Diagramma labiosum Diploprion bifasciatum Dischistodus perspicillatus Echeneis naucrates Echinoidea sp. Elapidae sp. Epinephelus areolatus Epinephelus bilobatus Epinephelus chlorostigma Epinephelus coioides Epinephelus lanceolatus Epinephelus malabaricus Epinephelus multinotatus Epinephelus polyphekadion Epinephelus sp. Eubalichthys caeruleoguttatus Eviota sp. Feroxodon multistriatus Fistularia commersonii Fistularia sp. Galeocerdo cuvier Gastropoda sp. Glaucostegus typus Gnathanodon speciosus Gobiidae sp. Gorgasia sp. Gymnocranius euanus Gymnocranius grandoculis Gymnocranius griseus Gymnocranius microdon WN 13.0 0.9 3.3 0.5 0.5 0.9 0.5 16.7 2.8 0.9 2.3 4.2 2.3 18.1 2.3 32.1 6.0 26.0 24.7 0.9 1.9 0.5 1.9 11.2 0.5 7.0 CR 3.4 0.9 1.7 0.9 2.6 2.6 0.9 8.6 0.9 0.9 1.7 7.8 5.2 0.9 38.8 0.9 2.6 29.3 20.7 1.7 21.6 0.9 8.6 0.5 0.9 0.9 1.9 0.9 0.9 0.5 27.0 3.7 1.4 13.5 18.1 3.3 1.7 3.4 2.6 0.9 0.9 16.4 11.2 5.2 6.9 - CS 1.9 1.0 2.9 1.0 2.9 8.7 1.0 49.0 2.9 1.9 1.9 1.0 8.7 1.0 2.9 1.9 2.9 1.0 - Binomial Gymnocranius sp. Gymnothorax flavimarginatus Gymnothorax javanicus Gymnothorax mccoskeri Gymnothorax sp. Gymnothorax thyrsoideus Gymnothorax undulatus Haemulidae sp. Hemigaleidae sp. Hemigymnus melapterus Heniochus acuminatus Heniochus diphreutes Heniochus sp. Heteroconger hassi Heteroconger sp. Hydrophis major Hydrophis ocellatus Hydrophis sp. Hydrozoa sp. Iniistius pavo Juvenile sp. Labridae sp. Labroides dimidiatus Lagocephalus lunaris Lagocephalus sceleratus Lagocephalus sp. Leptojulis cyanopleura Lethrinidae sp. Lethrinus amboinensis Lethrinus atkinsoni Lethrinus erythropterus Lethrinus laticaudis Lethrinus miniatus Lethrinus nebulosus Lethrinus olivaceus Lethrinus punctulatus Lethrinus rubrioperculatus Lethrinus sp. Lutjanus argentimaculatus Lutjanus carponotatus Lutjanus erythropterus Lutjanus johnii Lutjanus lemniscatus Lutjanus malabaricus Lutjanus monostigma Lutjanus russellii WN 2.8 CR 2.6 CS 0.5 0.5 1.4 0.5 1.4 1.4 0.9 0.5 0.5 4.2 0.5 0.5 0.9 10.2 14.0 0.5 12.6 0.5 3.3 0.5 0.5 9.3 25.6 17.2 30.2 40.5 2.8 1.4 0.5 10.2 1.9 0.9 0.5 - 0.9 1.7 1.7 0.9 2.6 0.9 0.9 1.7 0.9 0.9 1.7 5.2 7.8 32.8 0.9 2.6 0.9 2.6 0.9 11.2 4.3 10.3 44.0 12.1 3.4 1.7 6.0 0.9 4.3 0.9 0.9 1.0 1.0 1.0 3.8 1.0 1.0 10.6 51.0 4.8 1.9 1.9 - - 97 Ch 3: Case study on the Wandoo field Binomial Lutjanus sebae Lutjanus sp. Lutjanus vitta Megalaspis cordyla Meiacanthus sp. Microdesmidae sp. Monacanthidae sp. Mullidae sp. Mulloidichthys flavolineatus Muraenidae sp. Naso brevirostris Naso fageni Naso sp. Natator depressa Nebrius ferrugineus Nemipteridae sp. Nemipterus furcosus Nemipterus sp. Nemipterus sp1 Neotrygon sp. Netuma thalassina Octopus sp. Ophichthidae sp. Ophiuroidea sp. Octopoda sp. Teuthida sp. Ostraciidae sp. Oxycheilinus orientalis Paguridae sp. Palinuridae sp. Parachaetodon ocellatus Paracirrhites sp. Parapercis sp. Parapercis xanthozona Paraplotosus butleri Parupeneus barberinus Parupeneus heptacanthus Parupeneus indicus Parupeneus pleurostigma Parupeneus sp. Parupeneus spilurus Pentapodus emeryii Pentapodus porosus Pentapodus sp. Pentapodus vitta Pinguipedidae sp. Plagiotremus sp. WN 41.4 1.9 2.3 0.9 0.9 7.4 0.5 7.4 0.5 0.5 0.5 0.5 0.5 2.3 0.5 38.1 17.2 7.0 0.5 12.1 0.5 0.5 0.5 0.5 7.9 0.5 1.9 0.5 2.3 0.5 0.5 3.3 8.8 16.3 0.9 6.0 4.7 34.9 4.7 3.3 0.5 CR 31.0 6.0 1.7 0.9 3.4 1.7 0.9 0.9 3.4 6.0 52.6 18.1 0.9 0.9 0.9 0.9 0.9 0.9 11.2 0.9 0.9 5.2 15.5 0.9 1.7 0.9 1.7 6.0 17.2 3.4 - CS 3.8 1.0 1.0 1.0 1.9 1.9 2.9 1.0 1.0 67.3 33.7 21.2 2.9 20.2 3.8 1.0 - Binomial Platax batavianus Platax orbicularis Plectorhinchus caeruleonothus Plectorhinchus flavomaculatus Plectorhinchus gibbosus Plectorhinchus vittatus Plectropomus areolatus Plectropomus maculatus Plectropomus sp. Polycheata sp. Pomacanthidae sp. Pomacanthus imperator Pomacanthus semicirculatus Pomacanthus sexstriatus Pomacanthus sp. Pomacentridae sp. Pomacentrus nagasakiensis Pristipomoides multidens Pseudobalistes fuscus Pseudobalistes sp. Pseudochromis sp. Pseudomonacanthus peroni Ptereleotris sp. Pterocaesio sp. Pterois volitans Rachycentron canadum Rhina ancylostoma Rhinidae sp. Rhinobatidae sp. Rhizoprionodon acutus Rhynchobatus sp. Rhynchostracion nasus Sarda orientalis Sarda sp. Saurida sp. Saurida undosquamis Scaridae sp. Scarus frenatus Scarus ghobban Scarus sp. Scolopsis monogramma Scolopsis sp. Scolopsis taenioptera Scomberoides commersonnianus Scomberoides lysan WN 7.4 0.5 CR - CS 1.0 - - 0.9 - 0.5 7.0 0.5 0.9 18.1 19.1 1.9 3.7 7.9 0.9 9.8 0.9 2.8 1.9 0.5 2.8 0.5 0.5 7.9 3.7 0.5 0.9 11.6 13.0 0.5 1.9 7.0 32.6 - 2.6 6.0 16.4 11.2 0.9 9.5 5.2 4.3 3.4 2.6 0.9 2.6 0.9 0.9 0.9 3.4 2.6 31.0 11.2 0.9 0.9 33.6 9.5 4.3 1.7 15.5 2.6 0.9 1.0 8.7 4.8 1.9 3.8 1.0 1.0 52.9 2.9 3.8 3.8 1.0 79.8 1.0 - 1.9 1.4 - 1.0 - 98 Ch 3: Case study on the Wandoo field Binomial Scomberoides sp. Scomberomorus commerson Scomberomorus sp. Scombridae sp. Scyphozoa sp. Selar sp. Sepia smithi Sepia sp. Seriola dumerili Seriola rivoliana Seriolina nigrofasciata Serranidae sp. Siganus punctatus Siganus sp. Sphyraena barracuda Sphyraena jello Sphyraena sp. Sphyrna mokarran WN 3.7 10.2 9.3 3.7 0.5 0.5 0.5 0.5 2.8 2.3 0.5 0.5 11.6 10.7 4.2 1.9 CR 0.9 16.4 12.9 1.7 0.9 19.8 2.6 7.8 0.9 0.9 0.9 CS 8.7 3.8 1.9 1.0 2.9 1.9 38.5 1.0 1.9 2.9 Binomial Stegostoma tigrinum Suezichthys cyanolaemus Suezichthys devisi Suezichthys soelae Suezichthys sp. Sufflamen fraenatum Symphorus nematophorus Synodontidae sp. Synodus sp. Synodus variegatus Taeniurops meyeni Tetraodontidae sp. Teuthida sp. Triglidae sp. Upeneus australiae Upeneus luzonius Valenciennea sp. Zabidius novemaculeatus WN 3.3 11.2 0.5 0.9 0.5 32.6 38.1 0.9 1.9 0.5 1.4 0.5 0.9 0.9 - CR 0.9 3.4 0.9 39.7 14.7 5.2 0.9 0.9 0.9 CS 1.9 4.8 1.0 2.9 1.0 1.0 1.0 - Appendix 3.5 Prevalence (%) of pelagic species recorded at WN, CR and CS. Prevalence refers to the number of deployments on which a taxon was observed, out of the total number of deployments at that site. Binomial Ablennes hians Acanthocybium solandri Alepes apercna Alepes kleinii Alepes sp. Alepes vari Aluterus monoceros Aluterus scriptus Aluterus sp. Apogonidae sp. Atule mate Auxis thazard Balaenoptera acutorostrata Brachyura sp. Cantherhines dumerilii Cantherhines pardalis Carangidae sp. Carangoides armatus Carangoides ferdau Carangoides fulvoguttatus Carangoides gymnostethus Carangoides sp. WN 5.8 3.8 1.9 19 1.9 27 65 7.7 1.9 40 1.9 1.9 9.6 1.9 37 12 3.8 3.8 9.6 CR 3 3 31 28 47 3 41 3 6 44 6 3 CS 5 18 18 41 32 55 5 5 50 36 5 5 27 Binomial Caranx ignobilis Caranx sexfasciatus Caranx sp. Carcharhinidae sp. Carcharhinus amblyrhynchos Carcharhinus amboinensis Carcharhinus brevipinna Carcharhinus falciformis Carcharhinus galapagensis Carcharhinus leucas Carcharhinus limbatus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sorrah Carcharhinus sp. Carcharhinus tilstoni Cestum veneris Cheloniidae sp. Clupeidae sp. Coryphaena equiselis Coryphaena hippurus Decapterus macarellus WN 1.9 1.9 3.8 1.9 21 9.6 3.8 15 1.9 1.9 21 40 54 13 58 1.9 9.6 5.8 25 1.9 - CR 6 28 6 3 6 6 28 47 6 53 13 3 - CS 50 50 14 36 50 23 59 18 5 41 5 5 5 99 Ch 3: Case study on the Wandoo field Binomial Decapterus sp. Delphinidae sp. Disteira major Echeneidae sp. Echeneis naucrates Elagatis bipinnulata Elapidae sp. Ephippidae sp. Eubalichthys caeruleoguttatus Fistularia sp. Galeocerdo cuvier Gnathanodon speciosus Hydrophis ocellatus Hydrophis sp. Hydrozoa sp. Istiompax indica Istiophoridae sp. Istiophorus platypterus Juvenile sp. Katsuwonus pelamis Labroides dimidiatus Lagocephalus sceleratus Makaira nigricans Megalaspis cordyla Metavelifer multiradiatus Mobula kuhlii Mobula sp. Monacanthidae sp. Natator depressa Naucrates ductor Nomeidae sp. Platax sp. Platax teira Priacanthus sp. Psenes sp. Rachycentron canadum Remora remora Remora sp. Sardinella sp. Scomberoides lysan Scomberomorus commerson Scomberomorus sp. Scombridae sp. Scyphozoa sp. Selar boops Selar sp. Sepia sp. WN 69 1.9 1.9 48 15 15 3.8 9.6 5.8 5.8 1.9 1.9 37 3.8 7.7 37 1.9 1.9 3.8 1.9 3.8 27 1.9 1.9 1.9 1.9 3.8 1.9 1.9 3.8 23 9.6 3.8 42 1.9 1.9 1.9 CR 66 3 63 9 6 6 6 9 3 3 13 3 3 3 13 3 6 6 3 6 6 3 6 25 3 - CS 86 86 5 9 18 5 5 5 9 18 18 18 5 23 5 5 5 14 5 5 9 9 32 32 5 5 5 27 - Binomial Seriola sp. Seriolina nigrofasciata Sphyraena barracuda Sphyraena sp. Sphyrna mokarran Teuthida sp. WN 17 31 60 1.9 - CR 31 38 6 16 3 CS 68 23 5 18 - 100 Ch 4: Dynamic cuttlefish mimicry CHAPTER 4 WILD OBSERVATION OF PUTATIVE DYNAMIC DECAPOD MIMICRY BY A CUTTLEFISH (SEPIA CF. SMITHI) van Elden S, Meeuwig JJ. 2020. Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi). Marine Biodiversity 50:93. K EYWORDS : S TEREO -BRUVS . C EPHALOPOD BEHAVIOUR . D ECAPOD MIMICRY . N OVEL FIELD OBSERVATION 4.1 ABSTRACT Stereo baited remote underwater video systems (BRUVS) are widely used to document diversity, abundance, and biomass of marine wildlife and record unusual behaviours. We observed a cuttlefish appearing to mimic decapod morphology and locomotion during a non-targeted BRUVS study on Australia’s Northwest Shelf. While the pharaoh cuttlefish Sepia pharaonis (Ehrenberg, 1831) is putatively thought to mimic the appearance of a hermit crab in a laboratory setting, our observation is the first wild record of decapod mimicry by a cuttlefish, tentatively identified as Sepia smithi (Hoyle, 1885). In situ observations increase our understanding of how cuttlefish behave in their natural environment while interacting with other species and provide opportunities to further our understanding of the source and breadth of these mimicry. 101 Ch 4: Dynamic cuttlefish mimicry 4.2 INTRODUCTION Mimicry at the organism level is a phenomenon whereby a plant or animal (the mimic) uses various signal emissions such as sound, colour, shape, or scent to plagiarise something living or non-living (the model), in order to deceive a predator or prey animal (the dupe) (Pasteur, 1982). Most cases of mimicry are static whereby the organism is in a permanent state of mimicry; for example the nonvenomous king snake Lampropeltis elapsoides (Holbrook, 1838) has similar ringed markings to the venomous coral snake Micrurus fulvius (Linnaeus, 1766), and these markings cannot be changed (Pfennig et al., 2001). Some organisms, however, have the ability to choose when to mimic a model. The bluestriped fangblenny Plagiotremus rhinorhynchos (Bleeker, 1852) for example, can change its appearance by “turning off” the colours which allow it to mimic the bluestreak cleaner wrasse Labroides dimidiatus (Valenciennes, 1839, Côté and Cheney 2005). Cephalopods have a highly advanced ability to rapidly change their appearance by altering various body pattern components such as colour, texture, posture, and locomotion (Hanlon, 2007; Hanlon and Messenger, 2018). The ability to swiftly change their body pattern is used by cephalopods for predator defence, feeding, mating, and communication (Hanlon and Messenger, 2018). A range of cephalopod species employ changes to body pattern in order to mimic other animals: Various species of octopus such as Macrotritopus defilippi (Vérany, 1851) and Thaumoctopus mimicus (Norman and Hochberg, 2005) mimic several animals including flatfish, parrotfish and banded sea-snakes (Hanlon et al., 2010; Huffard et al., 2010; Norman et al., 2001), while juvenile meso-pelagic squid Chiroteuthis calyx (Young, 1972) have been documented to mimic siphonophores (Burford et al., 2015). Evidence of mimicry in cuttlefish is limited to a few species, including reports of small male giant cuttlefish Sepia apama (Gray, 1849) mimicking females to improve their chances of mating (Hall and Hanlon, 2002; Norman et al., 1999), and juvenile stumpy-spined cuttlefish Sepia bandensis (Adam, 1939) mimicking snails (Warnke et al., 2012). Okamoto et al. (2017) described for the first time a unique ‘arm-flapping’ behaviour observed in the pharaoh cuttlefish Sepia pharaonis in aquaria during a laboratory study and hypothesised it to be a case of hermit crab mimicry. This “crustacean-like 102 Ch 4: Dynamic cuttlefish mimicry aggressive mimicry” is described in detail by Nakajima and Ikeda (2017). Here, we report the first known observation in the wild of decapod mimicry by a cuttlefish Sepia sp. and discuss possible reasons for this behaviour by comparing the situation in which this behaviour was observed with the descriptions of this behaviour by Okamoto et al. (2017) and Nakajima and Ikeda (2017). 4.3 MATERIALS AND METHODS Stereo baited remote underwater video systems (BRUVS) are a non-destructive sampling method that is well established for documenting diversity, abundance, size structure and biomass of marine communities (Cappo et al., 2006). Stereo-BRUVS have been developed for benthic and mid-water environments (Bouchet et al., 2018b; Whitmarsh et al., 2017), and because they are relatively inexpensive, they can be deployed across large spatial scales (Letessier et al., 2013b). BRUVS have been shown to sample wide range of taxa beyond those attracted by the bait, including herbivores and planktivores, and documented taxa ranging from krill to turtles to whales (Bouchet et al., 2018b; De Vos et al., 2014; Letessier et al., 2013a, 2015a; Thompson et al., 2019; Watson et al., 2010). More recently, stereo-BRUVS have been used to document the behaviour of a variety of marine organisms observed as part of broader studies, including fish, sharks, and lobsters (Barley et al., 2016; Birt et al., 2019; Fox and Bellwood, 2008; Weiss et al., 2006). Stereo-BRUVS were deployed at three sites in north-western Australia (Fig. 4.1) as part of a broad ecological study: a reef comprising rocky substrate and various sessile invertebrates such as sponges and gorgonian corals (Site 1); an offshore oil platform situated on flat, sandy habitat with patchy sessile invertebrate coverage, predominantly sponges and gorgonian corals (Site 2); and an open, sandy site with no physical relief (Site 3). Mean sea surface temperature (SST) was similar across all three sites, ranging from 23.55 °C in the Austral spring to 30.20 °C in the Austral autumn. Depth was also similar across all sites, with a depth range of 43 - 57.7 m. Stereo-BRUVS consist of two video cameras mounted on a base bar 80 cm apart, converging at an angle of four degrees to a common focal point. Cameras were set to medium field of view and 1080 p resolution. As per standard BRUVS practices of using oily, soft-bodied fish as bait (Langlois et al., 2018), stereo-BRUVS were baited with 800 g of pilchards 103 Ch 4: Dynamic cuttlefish mimicry (Sardinops spp.), in a bait bag made of galvanised steel mesh, suspended in front of the cameras on the end of a 1.5 m long PVC plastic tube. A total of 125 stereo-BRUVS were deployed in this study using standard practices (Langlois et al., 2018), with five stereo-BRUVS being deployed in a set, and each camera recorded for a minimum of 60 min. All footage was analysed using EventMeasure (Seagis, 2017), which allows for identification of all taxa, abundance counts using the MaxN abundance metric, as well as length measurements. 4.4 RESULTS This behaviour was recorded at a depth of 50.8 m, at 20.124° S and 116.440° E at 07:20 am on 20 April 2018, with the location characterised by flat, mainly sandy habitat. It occurred seven minutes into the 60 minute video sample and the duration of the behaviour was 45 seconds. During this recording, two known predators of cuttlefish were also recorded (Froese and Pauly, 2019): the milk shark Rhizoprionodon acutus (Rüppell 1837), 65.24 cm long and recorded 26.9 minutes into the video and brushtooth lizardfish Saurida undosquamis (Richardson 1848), 41.7 cm long and recorded 27.6 minutes into the video. At the time of the cuttlefish observation, there were no other animals in the video. A total of five cuttlefish were observed across 125 BRUVS deployments, however the reported behaviour was only observed once (Table 4.1). A total of 53 decapods were observed on during this study, including 51 hermit crabs, one blue swimmer crab Portunus armatus (A. Milne-Edwards, 1861) and one painted rock lobster Panulirus versicolor (Latreille, 1804). Table 4.1 Record of all cuttlefish seen on BRUVS deployments with information on habitat, depth, sea surface temperature (SST), estimated visibility (vis) and activity for each of the three sites: A reef comprising rocky substrate and various sessile invertebrates Date Species Site Habitat Depth SST Activity (m) (°C) 4/10/2017 Sepia sp 1 Sand 53.2 24.65 Swimming; sitting 20/04/2018 Sepia sp cf. 2 Sand 50.8 30.13 Crustacean-like smithi aggressive mimicry 23/04/2018 Sepia sp 3 Sand 54.3 30.20 Swimming; hovering 17/09/2018 Sepia sp 3 Sand 56.4 23.93 Swimming; arms fully extended 7/09/2019 Sepia sp 2 Sponges; soft 52 23.63 Swimming; arms curled corals 104 Ch 4: Dynamic cuttlefish mimicry A cuttlefish, Sepia sp. with a mantle length of 12.2 cm was recorded at Site 2 approaching the bait bag. The first (dorsal-most) pair of arms were raised vertically and the distal ends darkened, resembling eyestalks, while the second and third pairs were bent, as if to appear jointed, and were used in a sideways ‘walking’ motion. The fourth (ventral-most) pair of arms was used to raise the head and arms of the cuttlefish off the substrate, so that the head was higher than the mantle and the tentacles were hidden (Fig. 4.2a). This body pattern is similar to the “crustacean-like aggressive mimicry” shown in Figure 5 of Nakajima and Ikeda (2017). There is also a flashing dark bar present at the base of the arms, similar to that displayed in Electronic Supplementary Material S1 and S2 in Okamoto et al. (2017). When close to the bait bag, the cuttlefish initially raised its head by extending the fourth pair of arms before swimming up to the bait bag approximately 30 cm above the seabed, and partially extending the second and third pairs of arms while approaching the bait (Fig. 4.2b). The cuttlefish then descended to the seabed and resumed the body pattern described above (Fig. 4.2c). The cuttlefish then moved away from the camera rig, maintaining decapod-like posture but ceasing the “walking” behaviour and instead swimming just above the substrate until it was no longer visible. 4.5 DISCUSSION We report here the first apparent observation of putative decapod mimicry by a cuttlefish in the wild. While the motivation for this behaviour is unclear from the video footage, we hypothesise that this mimicry may be a method of predator avoidance. The observation occurred in a habitat with little to no benthic cover to offer the cuttlefish protection from predators. A hard-bodied organism such as a crab would present as a less attractive target for the typical predators of a soft-bodied cuttlefish. This was also consistent with Okamoto et al. (2017), where they hypothesised that S. pharaonis was mimicking a hermit crab in their study possibly to avoid predators, but recommended further investigation of this behaviour both experimentally and in the wild to validate their hypothesis. An alternative hypothesis is that the cuttlefish here was using an aggressive, rather than defensive, form of mimicry. Okamoto et al. (2017) observed this aggressive mimicking behaviour while cuttlefish were hunting prey in an aquarium. In our 105 Ch 4: Dynamic cuttlefish mimicry observation, it is possible that the cuttlefish was also using mimicry while approaching potential prey, in this case the bait. Due to this observation occurring in the wild, without control of all potential behavioural triggers, we can only hypothesise on the motivation behind the observed mimicry. Figure 4.1 Selected frames from the video image (Online Resource 1): Sepia sp. approaches the bait bag while mimicking decapod (a), extends its arms while investigating the bait bag (b), before moving away from the camera mimicking decapod locomotion (c). 106 Ch 4: Dynamic cuttlefish mimicry As non-cuttlefish experts, we elicited expert advice (Dr Mandy Reid, Malacology Collection Manager, Australian Museum) who suggested the individual was most likely Sepia smithi, with the caveat that it is difficult to identify cuttlefish based on images alone. This tentative identification was made based on the white band over the mantle and eyes of the cuttlefish, as well as the habitat type and time of day of the activity. We also reviewed the literature to narrow down the potential species pool based on parameters such as distribution, depth of observation, size, and habitat as derived from SeaLifeBase (Palomares and Pauly, 2019), Atlas of Living Australia (www.ala.org.au, 2020) and CephBase (www.cephbase.eol.org, 2020). Of the approximate 111 species of the genus Sepia globally, 35 are found in Australia. There are five species that overlap in distribution, depth and size with our observed individual, allowing some latitude on habitat association and maximum mantle length (Table 4.2), including S. smithi. Sepia smithi is native to the region where our observations were made and this individual’s size would make it an adult of this species. While the species of cuttlefish could not be confirmed from the stereo-BRUVS footage, the behaviour observed in the wild and presented in this paper appears to provide an in situ example of “crustaceanlike aggressive mimicry” previously only described from captive cuttlefish behaviour (Nakajima and Ikeda, 2017; Okamoto et al., 2017). It is unclear if there are other cases of congeneric dynamic mimicry in the animal kingdom, but we speculate that the high cognitive ability of coleoid cephalopods would make it possible for multiple species of cuttlefish to display similar forms of crustacean-like aggressive mimicry, where the particular model being mimicked could vary by species and/or environment. This could be a case of convergent evolution as these congeners overlap in habitat and are possibly targeted by similar predators. Crustacean-like aggressive mimicry is still a relatively novel behaviour in the literature, and as such warrants significant further research in order to determine the prevalence of this behaviour within the genus Sepia. 107 Ch 4: Dynamic cuttlefish mimicry Table 4.2 Cuttlefish species found in the study region with information on maximum length (TL; cm), mantle length at maturity (ML; cm), depth range (m), habitat association and diel activity where available. Taxon authorities are provided for species not previously mentioned in this manuscript. Derived from SeaLifeBase (Palomares and Pauly, 2019), Atlas of Living Australia (www.ala.org.au, 2020) and Cephbase (www.cephbase.eol.org, 2020). Species Sepia latimanus Quoy and Gaimard 1832 Common name TL ML Depth broadclub cuttlefish 50 16 8-55 Sepia pharaonis Sepia elliptica Hoyle 1885 pharaoh cuttlefish 43 12 0-130 17.5 9.9 10-142 Sepia smithi Sepia papuensis Hoyle 1885 Smith's cuttlefish 17 na 7-138 Papuan cuttlefish 11 na 10-155 Habitat Diel Activity Diurnal ovalbone cuttlefish Reef associated Soft bottom (sand); seagrass Benthic (unspecified) Soft bottom (sand; mud) Soft bottom (sand; silt; mud) Nocturnal n/a Diurnal Nocturnal The use of stereo BRUVS to document diversity, abundance, size distributions and biomass in a wide range of marine environments is well documented (Whitmarsh et al., 2017). More recently, they have also been the basis of reports on unusual behaviours such as knotting in moray eels (Barley et al., 2016). As BRUVS allow us to increase the time spent observing marine animals in situ, without the influence of humans in the vicinity, they are likely to continue to unveil a wide range of rare and elusive behaviours, including mimicry, which will help further our understanding of how marine animals behave and interact in their natural environments. The five cuttlefish observations in 250 hours of video in this study show that stereo-BRUVS may not be the most efficient method for studying cuttlefish behaviour, however stereoBRUVS have previously been adapted to target particular species. The same stereoBRUVS used here have been used, unbaited, to successfully observe the behaviour of Antarctic krill Euphausia superba (Dana, 1850) in aquaria (Letessier et al., 2013a). A significant amount of the existing knowledge about cephalopod behaviour has come from experiments and laboratory studies (Hanlon and Messenger, 2018). Further video observation of cephalopods in the wild increases our understanding of their complex behaviour, interactions with other species, and the environmental factors that drive these behaviours. 108 Ch 4: Dynamic cuttlefish mimicry 4.6 ACKNOWLEDGEMENTS We would like to thank Dr Mandy Reid, Malacology Collection Manager at the Australian Museum, for her help with a tentative identification of the cuttlefish observed in the BRUVS footage. Our thanks to the Vermilion Oil and Gas Australia (Pty) Ltd. for their support of this project. 4.7 STATEMENTS Funding This research forms part of a Ph.D. thesis funded by the VOGA Ph.D. Scholarship in Rigs-to-Reefs Ecology, awarded to SVE by the University of Western Australia with funds donated by the Vermilion Oil and Gas Australia (Pty) Ltd. Conflicts of interest/Competing interests The authors declare that they have no conflict of interest. Ethical Approval Experimental protocols were approved by the University of Western Australia’s Animal Ethics Committee (RA/3/100/1484), and were carried out in accordance with the approved guidelines. Sampling and field studies: All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities. Data Availability All data generated or analysed during this study are included in this published article and its supplementary information files. Authors' contributions SVE and JM conceived the manuscript. SVE wrote the first draft of the manuscript. Both authors contributed to the manuscript revision, read, and approved the submitted version. 109 Ch 4: Dynamic cuttlefish mimicry 4.8 REFERENCES Adam W (1939) Sepia bandensis. Bull du Musée R d’Histoire Nat Belgique 15:1 Barley SC, Mehta RS, Meeuwig JJ, Meekan MG (2016) To knot or not? Novel feeding behaviours in moray eels. 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Accessed 4 Aug 2020 Young RE (1972) The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson Contrib to Zool 97:69 112 Ch 5: Threatened elasmobranchs CHAPTER 5 ELEVATED ABUNDANCE OF THREATENED ELASMOBRANCHS AROUND AN OFFSHORE OIL FIELD IN AUSTRALIA Target Journal: Conservation Biology K EY WORDS : O FFSHORE PLATFORMS ; DE FACTO MPA; IUCN RED L IST ; P LATFORM ECOLOGY ; S TEREO -BRUVS 5.1 ABSTRACT Human activity is degrading ecosystems around the world. Overfishing is ubiquitous and poses a threat to both target and non-target animals. Elasmobranchs are at particularly high conservation risk as a result of exploitation due to their conservative life histories, with most target fisheries for these animals assessed as unsustainable, and high mortality rates for elasmobranch bycatch. Offshore oil and gas platforms are productive marine ecosystems that support a wide range of species. These platforms act as both artificial reefs and fish aggregating devices, and can be classified as novel ecosystems. Offshore platforms may also function as de facto marine protected areas (MPAs) by excluding fishing activity which renders them potential refuges for species at risk from fishing. We here contrast the threatened elasmobranch community at the Wandoo oil platform and adjacent natural habitats in Northwest Australia, with those from other comparable regions across tropical Australia. The abundance of threatened elasmobranchs was higher around the offshore platform than most other regions, including locations in the Great Barrier Reef and Ningaloo Reef MPAs. The Wandoo platform is located in an area of commercial fishing activity, and many of the elasmobranchs observed at the Wandoo locations are captured as bycatch in the Pilbara Fish Trawl Interim Managed Fishery. Fishing is excluded around the Wandoo infrastructure, and we suggest that Wandoo acts as an important refuge from fishing pressure for these threatened elasmobranchs. A network of de facto MPAs created by offshore platforms in NW Australia may augment populations of threatened elasmobranchs both around the platforms and in adjacent natural habitats. 113 Ch 5: Threatened elasmobranchs 5.2 INTRODUCTION Human activity is significantly altering Earth’s natural habitats and threatening the survival of the species that depend on them. Globally, species are being lost at an unprecedented rate in the Holocene in what is now referred to as the sixth mass extinction (Ceballos et al., 2017; Dulvy et al., 2009; Turvey and Fritz, 2011). The number of threatened species, those classified as Vulnerable, Endangered or Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List (Mace et al., 2008a), is rising every year. There are over 32,000 threatened species in 2020, more than double the 15,465 threatened species in 2010 (IUCN, 2020). Threatened species are those at highest risk of extinction, and these species are consequently an important consideration in conservation research and management (Mace et al., 2008). Overfishing is arguably the biggest threat to ocean wildlife for both target and nontarget species (Jackson et al., 2001). Catching power of industrial fisheries increased rapidly post World War II, with significant advances in technology allowing fleets to travel further and catch more fish (Tickler et al., 2018). Global catch peaked at 130 million tonnes in 1996 and has declined in the years since (Pauly and Zeller, 2016). Signs of overfishing are detectable in large marine ecosystems as far back as the 1800s (Roberts, 2007) and today, even remote coral reefs show signs of overexploitation (Coll et al., 2008; Greer et al., 2014). Approximately 4.5 billion people are dependent on the oceans for at least 15% of their protein consumption, particularly in developing nations, and this number is anticipated to grow as the global population increases and climate change threatens global food security (Béné et al., 2015). The effects of overfishing are exacerbated by various other human impacts, including climate change, coastal development, noise pollution, aquaculture, eutrophication, and ocean plastification (Jackson, 2010; McCauley et al., 2015; Perring and Ellis, 2013). Human activity is causing habitat loss and defaunation, with 29% of seagrasses, 30% of coral reefs, and 35% of mangroves lost or degraded (Jackson, 2010). Populations of large marine animals have on average declined by 89% (Lotze and Worm, 2009), and it is estimated that by 2050, 99% of seabirds will have ingested plastic in their lifetimes (Wilcox et al., 2015). 114 Ch 5: Threatened elasmobranchs Elasmobranchs are particularly at risk in degraded oceans. Their K-selected life histories mean that they mature slowly and have low fecundity which translates to generally low productivity (Dulvy et al., 2008; Field et al., 2009). Each year, millions of elasmobranchs are either targeted for their meat, fins, livers, and gill plates, or captured as bycatch (Oliver et al., 2015). The global annual elasmobranch catch is approximately 1.7 million tonnes (Sadovy de Mitcheson et al., 2018), while the proportion of this catch estimated as sustainable is 200,000 tonnes, or 12 % (Simpfendorfer and Dulvy, 2017). Targeted shark fisheries have a poor record of sustainability and a significant portion of these shark populations will require decades to recover from overfishing (Stevens et al., 2000). Of the 1,084 elasmobranch taxa assessed by the IUCN, 213 species (20%) are listed as threatened (IUCN, 2020). A further 411 elasmobranch species (38%) are listed as Data Deficient, which should be afforded the same protection as threatened species until more information is available (Mace et al., 2008). Australia’s fisheries management is considered to be at the forefront globally (Ogier et al., 2016). However, many of Australia’s shark populations are in decline due to overfishing and other destructive practices such as beach netting (Gibbs et al., 2020; Momigliano et al., 2014; Roff et al., 2018). Furthermore, Australia’s MPAs are highly residual to commercial uses (Devillers et al., 2015), established largely offshore in nonrepresentative habitats, and are predominantly comprised of multiple-use zones, with only 9.5% of Australian waters fully protected from extraction (Marine Conservation Institute, 2018). Multiple-use zones allow recreational and/or commercial fishing activity, and therefore only offer partial protection for marine species including elasmobranchs (Lynch et al., 2010; Sciberras et al., 2015). Partial protection has limited conservation outcomes relative to high levels of protection (Lester and Halpern, 2008; Sciberras et al., 2015) and may be even less effective for large predators. There are 73 elasmobranch species in Australia listed as either Vulnerable, Endangered or Critically Endangered by the IUCN (IUCN, 2020). Of these species, 25 are also protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II (CITES Secretariat, 2020). However, only six of 115 Ch 5: Threatened elasmobranchs Australia’s internationally listed elasmobranch species are included under the national Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act; Commonwealth of Australia, 1999). Furthermore, the EPBC Act allows for limited exports of certain species protected under CITES Appendix II, including the Endangered scalloped hammerhead Sphyrna lewini (up to 200 tonnes a year), and Critically Endangered great hammerhead Sphyrna mokarran (up to 100 tonnes a year). Australia also allows for recreational fishing of Endangered shortfin mako sharks Isurus oxyrinchus and longfin mako sharks Isurus paucus (Bruce et al., 2014; Commonwealth of Australia, 1999). Studying threatened elasmobranchs is inherently challenging since they occur in low abundance and are highly mobile (Guttridge et al., 2017; Moore, 2015). Most data on threatened elasmobranchs are collected from dead animals in the form of data collected from commercial fisheries, fins and gill plates found in markets, and jaws and rostra kept as curios (Abercrombie et al., 2005; Moore et al., 2010; Morgan et al., 2011; Pank et al., 2001; Stobutzki et al., 2002). However studying these species while they are still alive, using non-invasive techniques, is possible. Baited remote underwater video systems (BRUVS) have recorded a variety of threatened elasmobranchs from locations all over the world, from scalloped hammerheads in Fiji (Brown, 2014), to green sawfish Pristis zijsron in Australia (Bond et al., 2018b), to leopard sharks Stegostoma tigrinum in the Red Sea (Spaet et al., 2016). BRUVS have also proved useful for recording novel behaviours and identifying hotspots for these species (Birt et al., 2019; Letessier et al., 2019). Offshore oil and gas platforms (hereafter offshore platforms) function as artificial reefs (Shinn, 1974) and are increasingly recognised as important marine habitats (Claisse et al., 2014; Sommer et al., 2019). These platforms create novel ecosystems with attributes not present at the site pre-installation, and are characterised by a shift in marine communities and generation of beneficial ecosystem services (Sommer et al., 2019; van Elden et al., 2019). Offshore platforms often exclude various fishing activities, effectively creating de facto marine protected areas (MPAs) that provide a refuge for marine wildlife. Various threatened elasmobranchs have been observed 116 Ch 5: Threatened elasmobranchs around offshore platforms and associated infrastructure, including grey nurse sharks Carcharias taurus, scalloped hammerheads, and great hammerheads (Franks, 2000; McLean et al., 2018b, 2019; Robinson et al., 2013). There have also been reports of aggregations of threatened elasmobranchs around offshore platforms, including whale sharks Rhincodon typus in Qatar and porbeagle sharks Lamna nasus in the North Sea (Haugen and Papastamatiou, 2019; Robinson et al., 2013). We investigate whether an offshore platform in Northwest (NW) Australia, the Wandoo oil field that lies approximately 75 km off the NW coast, could be acting as a refuge for threatened elasmobranchs across tropical Australia. We harnessed two curated stereo-BRUVS databases, one for demersal and one for pelagic taxa, to examine the abundance of threatened elasmobranchs around the Wandoo oil field infrastructure and two associated natural habitats, relative to abundances across five comparable regions around Australia with a geographical span of approximately 16 degrees of latitude and 50 degrees of longitude. We tested the hypothesis that the novel ecosystem that has emerged at the Wandoo Field, which has functioned as a de facto MPA for over 25 years, is acting as a refuge for threatened elasmobranchs. 5.3 MATERIALS AND METHODS Video-based sampling of elasmobranchs Our analysis is based on video imagery derived from stereo-BRUVS. Stereo-BRUVS are an established, non-destructive sampling method for studying the distribution, abundance, biomass and diversity of marine fauna (Barley et al., 2017; Cappo et al., 2006; Watson et al., 2010). More recently, stereo-BRUVS have also documented rare and highly mobile species (Letessier et al., 2013b, 2015a; Thompson et al., 2019). Stereo-BRUVS are relatively inexpensive, allowing them to be deployed across large spatial scales (Letessier et al., 2013b, 2015b), and they have been developed to sample both benthic and mid-water habitats (Letessier et al., 2013b; Whitmarsh et al., 2017). BRUVS-derived data should be interpreted recognising the potential higher representation of piscivores (Lowry et al., 2012), the potential variability of bait plumes (Whitmarsh et al., 2017). Depsite these constraints, BRUVS can be used to 117 Ch 5: Threatened elasmobranchs document clear signals in marine communities relative to other methods (Cappo et al., 2006; Lowry et al., 2012). Stereo-BRUVS, whether used on the seabed or in mid-water habitats, share a common design. Seabed stereo-BRUVS consist of a 95 cm long aluminium horizontal base bar that supports two small action (e.g. GoPro) video cameras. The video cameras are mounted 80 cm apart and converge to a common focal point at an angle of four degrees per camera, and each camera records for a minimum of 60 min. The stereoBRUVS are baited with ~800 g of pilchards Sardinops sp. in a bag made of either plastic coated wire or galvanised steel mesh. Bait is suspended on a pole 1.5 m in front of the cameras (Supplementary Fig. 5.1a). Each camera is set to record in medium field of view to maximise the area in the video frame and to increase rates of detection to a distance up to 8 m. Seabed stereo-BRUVS are deployed individually on the seabed with a minimum of 200 m between stations. Mid-water stereo-BRUVS use the same basebar as seabed stereo-BRUVS. The basebar is mounted on a 1.45 m long steel upright to provide stability in the water column (Supplementary Fig. 5.1b). Mid-water stereo-BRUVS are baited with 1 kg of crushed pilchards, contained in a perforated PVC canister. The canister is mounted 1.5 m in front of the cameras on a steel bait arm, which acts as a rudder to minimise rotation and maintain a down-current field of view for the duration of the deployment. Mid-water stereo-BRUVS are suspended 10 m below the surface and each camera records for a minimum of 120 minutes and are generally deployed in long-lines (strings) of five rigs separated by 200 m of line. However, rigs were randomly moored in sets of five within stratified zones in the Wandoo field to avoid entanglement with infrastructure. Established stereo-BRUVS protocols are followed pre-survey, during deployments and post-survey to ensure consistency in obtaining and recording stereo-BRUVS imagery (Bouchet et al., 2018b; Langlois et al., 2018). Prior to fieldwork, stereo-BRUVS are calibrated in an enclosed swimming pool using the CAL software (SeaGIS Pty Ltd, 2020), following standard protocols (Harvey and Shortis, 1998). Collected videos are converted to AVI format using Xilisoft Video Converter Ultimate (Xilisoft Corporation, 2016) before being imported into the EventMeasure software package (SeaGIS Pty Ltd, 118 Ch 5: Threatened elasmobranchs 2020) for processing. Prior to the deployment of each BRUV in the field, a slow hand clap is recorded in the shared field of view to enable synchronising of the left and right cameras videos in the lab prior to processing. Processing commences either once the seabed stereo-BRUVS have settled on the substrate or once the mid-water stereoBRUVS have stabilised at the set depth of 10 m. All animals are identified to the lowest possible taxonomic level. Relative abundance is estimated as the maximum number of individuals of a given species in a single frame (MaxN; Cappo et al., 2006). We accessed the seabed and mid-waters BRUVS databases curated by the Marine Futures Lab (https://meeuwig.org/resources). To reflect known latitudinal gradients in biodiversity (Forster, 1778), our analysis was restricted to regional, largely tropical locations, comparable to the Wandoo locations, with a latitude range of 16 degrees (9.9 to 26.3 °S) and longitude range of 50 degrees (96.8 to 146.8 °E). Demersal elasmobranch data were extracted from the seabed database of 3,920 seabed stereoBRUVS deployments collected at 26 locations over 33 surveys. The data for pelagic elasmobranchs were extracted from 2,268 two hour video samples from 26 locations over 33 surveys (Supplementary Tables 1 and 2). These locations were assigned to six regions (Fig. 5.1), roughly corresponding to the Western Australian (WA) bioregions as defined by the WA Department of Primary Industries and Regional Development (DPIRD; Gaughan and Santoro, 2019), and the Integrated Marine and Coastal Regionalisation of Australia (IMCRA) provincial bioregions (Commonwealth of Australia, 2006). The regions are: Northeast (NE), which encompasses IMCRA’s Northeast IMCRA transition and Cape Province; the remote offshore Australian territory of the Cocos-Keeling Islands (CI); Northwest (NW), corresponding to DPIRD’s North Coast with latitudes less than 21.46° S and including the Muiron Islands; Central North (CN), corresponding to IMCRA’s Central Western IMCRA Transition (21.46° S to 24° S); and Central South (CS), corresponding to IMCRA’s Central Western IMCRA Province (24° S to 27° S). The Wandoo locations were classified separately from the NW region in which they are located to allow them to be contrasted against the other locations. The Wandoo locations include both artificial and natural habitats. The Wandoo Platform location (WP) is located 75 km northwest of Dampier, Western Australia (Fig. 5.2). The infrastructure at the Wandoo Platform includes: a catenary 119 Ch 5: Threatened elasmobranchs anchored leg mooring (CALM) buoy, secured by six moorings around the pipeline end manifold (PLEM); Wandoo A, an unmanned monopod platform consisting of production infrastructure with a helideck supported by a 2.5 m diameter shaft; and Wandoo B, a concrete gravity structure (CGS) with a caisson measuring 114 m long by 69 m wide, and four shafts 11 m in diameter supporting the superstructure 18 m above the surface (Fig. 5.3). The Wandoo Reef (WR) location is located approximately 15 km west of the Wandoo Platform, and is characterised by a natural rocky reef rising approximately 30 m from the seafloor. It was chosen as a natural comparison of the artificial structure that is the Wandoo field. The Wandoo Sand (WS) location is situated approximately 15 km northeast of WP and is characterised by little to no physical relief and a dense, silty sand habitat. This habitat is likely similar to the Wandoo field prior to the installation of infrastructure. Figure 5.1 Location of the study regions around Australia: Cocos-Keeling Islands (pink; to the northwest of the Australian mainland); Northeast (red); Northwest (orange); Wandoo (yellow) Central North (dark green); and Central South (light green). 120 Ch 5: Threatened elasmobranchs All stereo-BRUVS were deployed according to standard practices (Bouchet et al., 2018b; Langlois et al., 2018). Sampling occurred during daylight hours to minimise any effects of crepuscular animal behaviour. We used a generalised random tessellation stratified (GRTS) approach (Stevens and Olsen, 2004) or random stratified approach (Kenkel et al., 1989), depending on the purpose of each survey. Surveys were conducted under UWA ethics permit RA/3/100/1484 and, if conducted on private vessels, under exemptions from the Australian Maritime Safety Authority (EX2016/A185; EX2017/A007). All necessary jurisdictional permits were obtained. Figure 5.4 Location of the Wandoo Platform and the two nearby natural locations, Wandoo Reef and Wandoo Sand, approximately 75 km north-west of Dampier, Western Australia Elasmobranch analyses All elasmobranch records from the tropical regions were extracted from the demersal and pelagic databases. Taxa observed on seabed stereo-BRUVS were classified as ‘demersal taxa’, even though some taxa recorded on seabed stereo-BRUVS were not necessarily demersal species. The same approach was applied to taxa observed on mid-water stereo-BRUVS which were classified as ‘pelagic taxa’ regardless of their habitat. The latest IUCN Red List classifications (accessed 27th August 2020) were obtained and used to classify all elasmobranch records according to the seven IUCN 121 Ch 5: Threatened elasmobranchs classifications: Critically Endangered (CR); Endangered (EN); Vulnerable (VU); Near Threatened (NT); Data Deficient (DD); Least Concern (LC); and Not Evaluated (NE) (IUCN, 2020). Where taxa were only identified to genus (9%) or family (2%), the most common IUCN classification was used for species in that genus or family known to occur at that location based on reported distributions accessed via Aquamaps (Kaschner et al., 2019). Threatened elasmobranchs, comprised of taxa listed as CR, EN and VU, were extracted from the demersal and pelagic databases as the focus of the analysis. Figure 5.7 Wandoo oil field schematic adapted from Vermilion Oil and Gas Australia (2014). The infrastructure at the Wandoo field includes the unmanned monopod Wandoo A, the concrete gravity structure Wandoo B, the pipeline end manifold (PLEM), and the catenary anchored leg mooring (CALM) Buoy. Not to scale. Our analysis was based on total abundance (TA) of elasmobranchs as we were interested in numeric abundance rather than size-based metrics such as length or weight. Total abundance of threatened elasmobranchs was calculated for each sample as the sum of abundances for all taxa on that sample. For demersal elasmobranchs, TAD was calculated for each individual deployment. For pelagic elasmobranchs, TA P was calculated as the mean abundance of the five deployments within the string or across each moored set in the case of the Wandoo locations. All samples with no 122 Ch 5: Threatened elasmobranchs threatened elasmobranchs were retained as zeros so that the mean abundances for locations reflected absences as well. For each taxa observed at the Wandoo locations, mean taxa-specific abundances were calculated for all locations. For each location, TAD and TAP were calculated as the average of all samples from that location as the basis for assessing differences between regions. The demersal and pelagic abundance data were compared between regions using both univariate and multivariate analyses. Total elasmobranch abundances at the three Wandoo locations were compared with those of the other regions using Wilcoxon Signed Rank tests with regions as replicates (Zar, 1999). The Wilcoxon Signed Rank test was also used to contrast the abundance of each threatened elasmobranch taxa at the Wandoo locations to their abundances across all other locations. For the multivariate analyses, we tested for differences in the composition of threatened elasmobranchs at the Wandoo locations relative to the other regions for both demersal and pelagic elasmobranchs. The abundance data for each location were log(x+1) transformed to increase the influence of rare taxa and reduce the influence of common taxa, and a Bray-Curtis resemblance matrix was calculated. A one-way permutational analysis of variance (PERMANOVA) was applied based on unrestricted permutations with “region” as the factor, followed by post-hoc paired tests where appropriate (Anderson, 2001). A canonical analysis of principal coordinates (CAP) was used to visualise a constrained ordination of the data for both the demersal and pelagic composition data. Environmental drivers We compiled a database of anthropogenic, physical, chemical and biological oceanographic variables for the seabed and mid-water locations (Supplementary Tables 3 and 4 respectively) to determine whether there were underlying environmental or anthropogenic drivers of the elasmobranch abundances. Anthropogenic variables using travel time were based on human accessibility assessments undertaken by Maire et al. (2016). Distance to market and population were computed using the LandScan 2016 database (Dobson et al., 2000), while distances to marine features were computed using bathymetry data (Yesson et al., 2020). Environmental data were derived from the following datasets: 123 Ch 5: Threatened elasmobranchs  Geoscience Australia (GA) 250 m bathymetry (Whiteway, 2009);  GA Australian submarine canyons (Huang et al., 2014);  CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and  Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020) The degree of colinearity amongst these independent variables was calculated using Pearson’s correlation coefficient (Kirch, 2008) such that if variables were highly correlated (r>0.6), only one of the pair was retained. We then examined the influence of these variables on the abundance of threatened elasmobranchs at the level of location, using a distance‐based linear model (DistLM) (Anderson et al., 2015). All analyses were completed using the Primer 7 software package with the PERMANOVA + add-on (Anderson et al., 2015). 5.4 RESULTS Elasmobranchs across Australia’s tropics were diverse and numerous. Across all regions, we counted 5,360 elasmobranchs from 93 taxa, representing 18 families. Threatened elasmobranchs accounted for 866 individuals (16%) from 35 taxa (38%), representing 15 families (83%). In the demersal dataset, we counted 3,538 individuals from 85 elasmobranch taxa, representing 17 families. Threatened elasmobranchs accounted for 592 individuals (17%) from 27 threatened elasmobranch taxa (31%), representing 12 families (71%) (Supplementary Table 5.5). The remaining taxa were classified as: NT (16%), DD (5%), LC (21%), and NE (27%). Within the threatened taxa, the majority were classified as Vulnerable (55%), followed by Critically Endangered (35%) and Endangered (10%). Wedgefish Rhychobatus sp. was the most prevalent threatened taxon, recorded on 127 deployments. At the Wandoo locations, we recorded 313 elasmobranchs (6% of all elasmobranchs recorded) from 27 taxa (29%), representing ten families (6%). Threatened elasmobranchs accounted for 89 individuals (28%) from 13 taxa (48%), representing eight families (80%). The remaining taxa at Wandoo were classified as: NT (26%), DD (7%), LC (4%), and NE (15%). Vulnerable species comprised 48% of all threatened elasmobranch taxa at the Wandoo locations, followed by Critically Endangered (38%) and Endangered (14%) species. The 124 Ch 5: Threatened elasmobranchs most prevalent taxa at the Wandoo locations were requiem shark Carcharhinus sp. and wedgefish, each recorded on 24 deployments. In the pelagic dataset we counted 1,822 individuals from 28 elasmobranch taxa, representing six families. Threatened elasmobranchs accounted for 1,041 individuals (56%) from 14 taxa (50%), representing five families (83%) (Supplementary Table 5.6). The remaining taxa were classified as: NT (28%), DD 11%), and LC (11%). Within the threatened taxa 55% were Vulnerable, while Endangered accounted for 34% and Critically Endangered accounted for 11%. The most prevalent threatened taxon was the requiem shark, recorded on 128 strings. At the Wandoo locations, we recorded 417 elasmobranchs (22% of all elasmobranchs recorded) from 17 taxa (61%), representing three families (50%). Threatened elasmobranchs accounted for 302 individuals (72%) from seven taxa (41%), representing three families (100%). The remaining taxa at Wandoo were classified as: NT (35%), DD (12%), and LC (12%). The threatened elasmobranchs at the Wandoo locations were mostly Vulnerable (73%), followed by Endangered (22%) and Critically Endangered (5%). The most prevalent threatened taxon at Wandoo was also the requiem shark, recorded on 60 strings. Comparing threatened elasmobranch abundance between regions Abundance of threatened elasmobranchs varied significantly between regions in both the demersal and pelagic datasets. Mean abundance of demersal threatened elasmobranchs was generally higher at the individual Wandoo locations than at most other regions, across which abundance ranged from 0.003 in the Cocos-Keeling Islands region to the highest value of 0.08 at the Wandoo Sand location (Fig. 5.4a). The remaining Wandoo locations, Wandoo Reef (TAD=0.06) and Wandoo Platform (TAD=0.05), had the second and fourth highest abundances respectively. Abundance of both Vulnerable and Endangered taxa were highest at Wandoo Sand (0.05 and 0.01 respectively), while abundance of Critically Endangered taxa was highest at Wandoo Reef (0.04). In terms of the individual Wandoo locations, Wandoo Platform was significantly higher than the other regions in the abundance of Endangered taxa and did not differ in the abundance of Vulnerable, Critically Endangered, and combined threatened taxa (Table 5.1). Wandoo Sand had significantly higher abundance of 125 Ch 5: Threatened elasmobranchs Vulnerable, Endangered, and combined threatened taxa than the other regions, and did not differ in the abundance of Critically Endangered taxa. Wandoo Reef had significantly higher abundance of Critically Endangered taxa, and did not differ from the other regions in the abundance of Vulnerable, Endangered or combined threatened taxa. Mean abundance of pelagic threatened taxa was also generally higher at the individual Wandoo locations, with abundance across all regions ranging from 0.07 in the CocosKeeling Islands region to 0.22 at Wandoo Sand (Fig. 5.4b). Pelagic abundance was highest at Wandoo Sand (0.22), followed by Central South (0.16), Wandoo Platform (0.15), and Wandoo Reef (0.15). Abundance of Vulnerable taxa was highest at Wandoo Sand (0.18), while abundance of Endangered taxa was highest at Central South (0.10). Abundance of Critically Endangered taxa was highest at Northeast (0.01). In terms of the individual Wandoo locations, Wandoo Platform did not differ from the other regions in the abundance of Vulnerable, Endangered, or combined threatened taxa, and was significantly lower in the abundance of Critically Endangered taxa (Table 5.1). Abundance at Wandoo Sand was significantly higher than the other regions in terms of both Vulnerable and combined threatened taxa, and did not differ in the abundance of either Endangered or Critically Endangered taxa. Abundance at Wandoo Reef was higher than the other regions in terms of Critically Endangered taxa, and did not differ in the abundance of Vulnerable, Endangered or combined threatened taxa. The taxa-specific comparisons of the abundances of the 13 demersal and six pelagic taxa recorded at the Wandoo locations indicated higher numbers for only a limited number of species. In terms of demersal taxa, Wandoo Platform had higher abundance of leopard sharks (EN) than the other locations (Z = -2.98; p = 0.003). Wandoo Sand had higher abundance of silky sharks Carcharhinus falciformis (VU) (Z = -2; p = 0.046) and requiem sharks (Z = -3.26; p = 0.001), and Wandoo Reef had higher abundance of wedgefish (CR) (Z = -3.23; p = 0.001). In terms of pelagic taxa, only requiem sharks (VU) were higher at the Wandoo locations than at other locations and this held for each location: Wandoo Platform (Z = -2.08; p = 0.038), Wandoo Sand (Z = -3.09; p = 0.002), and Wandoo Reef (Z = -2.47; p = 0.013). 126 Ch 5: Threatened elasmobranchs Table 5.1 Wilcoxon Signed Rank tests comparing mean abundance of demersal and pelagic threatened elasmobranchs at the three Wandoo locations with the means of the other tropical regions. Tests were conducted for Vulnerable (VU), Endangered (EN) and Critically Endangered (CR) taxa, as well as all of these taxa combined (Total). P-values in bold and marked with an asterisk are < 0.05. VU Demersal Wandoo Platform Wandoo Sand Wandoo Reef Pelagic Wandoo Platform Wandoo Sand Wandoo Reef EN CR Total Z P-value Z P-value Z P-value -0.423 0.673 -2.282 *0.022 -0.761 0.447 -2.113 *0.035 -2.282 *0.022 -0.930 0.353 -0.085 0.933 -0.592 0.554 -2.282 *0.022 -0.592 0.554 -2.282 *0.022 -1.606 0.108 Z P-value Z P-value Z P-value -1.099 0.272 -2.282 *0.022 -1.268 0.205 -0.423 0.673 -0.085 0.933 -0.592 0.554 -2.113 *0.034 -1.268 0.205 -2.113 *0.035 -1.099 0.272 -2.282 *0.022 -0.930 0.353 Differences in threatened elasmobranch community assemblages Our analysis showed weak differences in the composition of threatened elasmobranchs between the locations in the Wandoo field and the regional locations. Following exploratory analyses, we excluded the offshore Cocos-Keeling Islands region as it was strongly separated from the other tropical regions, and this separation overwhelmed the differences in taxonomic assemblages among the other regions. Demersal assemblages did not show strong separation among the regions, with no significant differences between the locations in the PERMANOVA (p = 0.242). Some regions still showed spatial separation and were characterised by different threatened taxa (Fig. 5.5a). The demersal assemblage at Wandoo Platform was characterised by leopard sharks, and was more similar to the Northeast and Northwest regions than to Wandoo Sand and Wandoo Reef. Wandoo Sand was characterised by requiem sharks while Wandoo Reef was characterised by wedgefish. Locations in the Northeast, Northwest, and Central North regions did not show any strong similarity within their regions, and the assemblages in these regions were similar, characterised by leopard sharks and tawny nurse sharks Nebrius ferrugineus (VU). Locations in the Central South region were more distinct from other regions, characterised by bentfin devilrays Mobula thurstoni (EN). 127 Ch 5: Threatened elasmobranchs Figure 5.10 Demersal (a) and pelagic (b) abundance of threatened elasmobranchs by region: Northeast (NE); Cocos-Keeling Islands (CI); Northwest (NW); Wandoo Platform (WP); Wandoo Sand (WS); Wandoo Reef (WR); Central North (CN); and Central South (CS). Classifications depicted are Vulnerable (yellow); Endangered (Orange) and Critically Endangered (Red). Patterned bars indicate the Wandoo locations. Pelagic taxonomic assemblages did not show strong separation In terms of abundance, with no significant differences between the assemblages in the PERMANOVA (p = 0.263), but spatial separation was observed between some regions (Fig. 5.5b). The pelagic assemblage at Wandoo Platform was characterised by mobula rays (VU) and sandbar sharks (VU), and was similar to the nearby natural locations Wandoo Sand and Wandoo Reef, Northeast, and one Northwest location (Long Reef West). These locations were characterised by mobula rays and great hammerheads (CR). Northwest showed weak grouping, with locations in this region characterised by great 128 Ch 5: Threatened elasmobranchs hammerheads and silvertips Carcharhinus albimarginatus (VU). Central North and Central South were each more separated from other regions, with Central North characterised by oceanic whitetips Carcharhinus longimanus (CR) and shortfin makos (EN), and Central South characterised by dusky sharks (EN). Environmental and anthropogenic drivers The environmental and anthropogenic variables explained a significant proportion of the variation in both the demersal and pelagic taxonomic assemblages in terms of abundance. The most parsimonious DistLM model explained 26% of the variation in the demersal taxonomic assemblages, with the most influential variables being depth, dissolved oxygen (O2), and sea surface temperature (SST) (Table 5.2). Demersal assemblages were predominantly influenced by environmental variables (O2 and SST, 15%), followed by physical variables (depth, 11%). In terms of the pelagic taxonomic assemblages, the most parsimonious DistLM model explained 41% of the variation, driven by travel time to market (TT_Market), distance to port (DistPort), and chlorophyll concentration (Chl-a) (Table 5.2). Pelagic assemblages were predominantly influenced by anthropogenic variables (TT_Market and DistPort, 29%), followed by environmental variables (Chl-a, 12%). Table 5.2 Distance-based linear model (DistLM) results based on the most parsimonious model predicting abundance of demersal and pelagic threatened elasmobranchs. Variables included are: depth (m); dissolved oxygen (O2; mmol/L); sea surface temperature (SST; °C); travel time to market (TT_Market; mins) distance to port (DistPort; km); Chlorophyll concentration (Chl-a; mg/m3). The degrees of freedom (d.f.) are reported in parentheses after the Pseudo-F value. proportion of variation in abundance explained by each variable (Prop.) and cumulative proportion of variation explained by the variables (Cumul. Prop.) are also included. Variable Demersal Depth O2 SST Pelagic TT_Market DistPort Chl-a SS(trace) Pseudo-F (d.f.) P Prop. Cumul. Prop. 6,435 5,465 3,785 2.9 (21) 2.2 (21) 1.5 (21) 0.005 0.031 0.141 0.11 0.09 0.06 0.11 0.20 0.26 8,461 6,206 5,856 3.0 (15) 2.4 (15) 2.5 (15) 0.007 0.025 0.039 0.17 0.12 0.12 0.17 0.29 0.41 129 Ch 5: Threatened elasmobranchs Figure 5.13 Canonical analysis of principal coordinates (CAP) for abundance of (a) demersal and (b) pelagic taxonomic assemblages. Locations shown are: Northeast (Red); Northwest (Orange); Wandoo Platform (yellow triangle); Wandoo Reef (yellow diamond); Wandoo Sand (yellow square); Central North (dark green); and Central South (light green). Taxa clockwise from top in (a) are: bentfin devilray Mobula thurstoni; wedgefish Rhychobatus sp.; requiem shark Carcharhinus sp.; silky shark Carcharhinus falciformis; leopard shark Stegostoma tigrinum; and tawny nurse shark Nebrius ferrugineus. Taxa clockwise from top in (b) are: oceanic whitetip Carcharhinus longimanus; dusky shark Carcharhinus obscurus; sandbar shark Carcharhinus plumbeus; requiem shark; mobula ray Mobula sp.; great hammerhead Sphyrna mokarran; and silvertip shark Carcharhinus albimarginatus. Images © R. Swainston/anima.fish 130 Ch 5: Threatened elasmobranchs 5.5 DISCUSSION The Wandoo oil field and adjacent natural habitats had elevated abundance of threatened elasmobranchs compared with other tropical regions around Australia. Wandoo is located within the Pilbara Offshore meso-scale region, which was subjected to decades of destructive seabed trawling activity (Sainsbury et al., 1993), and is still targeted by three commercial fisheries as well as recreational fishing activity (WAFIC, 2020). Despite this fishing pressure, there were more threatened elasmobranchs at the Wandoo locations than at locations on the Ningaloo Reef and the Great Barrier Reef, both of which are managed as multiple-use MPAs. Several threatened taxa were found in higher abundance at the Wandoo locations than other regions, suggesting that this area could be of particular importance for elasmobranchs such as silky sharks (VU), leopard sharks (EN), and wedgefishes (CR). The demersal taxonomic assemblages varied between the Wandoo locations, despite environmental similarities between these sites. It is likely that the distinction in the Wandoo Platform demersal assemblage is driven by the presence of the artificial infrastructure. Offshore platforms have a significant impact on demersal communities by creating greater habitat complexity that results in higher fish diversity and production (Claisse et al., 2014; Love et al., 2019b). In the case of the Wandoo Platform location, the installation of the infrastructure resulted in a change in in both habitat composition and community assemblages from what would have existed preinstallation (van Elden et al. in prep) and consequently may provide unique habitat and ecosystem services for demersal threatened elasmobranchs. The novel nature of this location was further emphasised by the presence of two threatened species at Wandoo Platform that were not recorded at either of the nearby natural locations: round ribbontail ray Taeniurops meyeni (VU) and giant shovelnose ray Glaucostegus typus (CR). The habitat at these two natural locations was generally sandy with little to no macrobenthos cover (van Elden et al. in prep). This is due to habitat modification from trawling activity, which would have historically removed macrobenthos (Sainsbury et al., 1993), particularly at Wandoo Sand, but also in the flat areas surrounding the Wandoo Reef. However, this sandy habitat remains important for various threatened demersal elasmobranchs including leopard sharks, wedgefishes, 131 Ch 5: Threatened elasmobranchs and bowmouth guitarfish Rhina ancylostoma (CR) (Compagno, 1984). It is likely that the presence of various undisturbed habitats over a relatively small spatial scale, including sandy and macrobenthos habitats, natural reefs, and artificial reefs, create a complex network of valuable habitats for demersal threatened elasmobranchs. The pelagic assemblages were similar across the Wandoo locations. This similarity is to be expected given the relatively close proximity of these sites, and the highly mobile nature of pelagic elasmobranchs (Andrzejaczek et al., 2020; Bonfil, 2008). Offshore platforms provide hard substrate vertically through the water column to the surface, which provides a unique physical environment not present in most natural habitats (Todd et al., 2018). Offshore platforms also function as fish aggregating devices (FADs; Franks 2000), attracting pelagic fishes which are a food source for threatened elasmobranchs such as dusky sharks, great hammerheads and sandbar sharks (Compagno, 1984), all of which were observed at the Wandoo locations. All three of these species are also known to feed on demersal species (Compagno, 1984), which are also found throughout the water column on the shafts of the Wandoo platforms (Tothill, 2019). It is likely that pelagic elasmobranchs, which are highly mobile, could be utilising all of the habitats in and around the Wandoo field for feeding and refuge from predators. Fishing activity has been identified as one of the key human-driven pressures on marine environments in NW Australia (Anon., 2018). We found that anthropogenic variables related to fishing activity, namely travel time to market and distance to port, were the most influential factors impacting pelagic assemblages. There were 12 threatened elasmobranch taxa recorded at the Wandoo locations (excluding unidentified requiem sharks) and of these, nine were reported as bycatch in the Pilbara Fish Trawl Interim Managed Fishery: sandbar sharks, round ribbontail rays, mobula rays, and tawny nurse sharks (all Vulnerable); leopard sharks (Endangered); and wedgefish, great hammerheads, bowmouth guitarfish and giant shovelnose rays (all Critically Endangered) (Jaiteh et al., 2014; Western Australia Department of Fisheries, 2010). Fishing mortality, both immediate and post-release, varies greatly in elasmobranchs (Ellis et al., 2017). Dapp et al. (2016) predicted that average mortality 132 Ch 5: Threatened elasmobranchs in trawl fisheries was 41.9% in stationary-respiring elasmobranchs (e.g. leopard and tawny nurse sharks) and 84.2% for obligate ram-ventilating species (e.g. sandbar and hammerhead sharks). However, in the case of the Pilbara Fish Trawl Interim Managed Fishery, independent observations of 44 trawls found that 91% of sharks and 66% of batoids captured in trawls were dead and consequently discarded (Jaiteh et al., 2014). As such, this fishery represents an ongoing and significant risk to threatened elasmobranchs. The Wandoo field and adjacent natural habitats had higher abundance of threatened elasmobranchs than locations at the Ningaloo Reef and Great Barrier Reef MPAs. Both of these MPAs are predominantly multiple-use, with only 34% of the Ningaloo Reef MPA and 33% of the Great Barrier Reef MPA protected in no-take zones (CALM and MPRA, 2005; Fernandes et al., 2005). MPAs that are multiple-use offer only partial protection from extractive activities, and are significantly less effective than no-take MPAs (Edgar et al., 2014; Lester and Halpern, 2008; Sciberras et al., 2015). Fish populations in partially protected zones of the Ningaloo and Great Barrier Reef MPAs show fishing-related impacts not observed in no-take zones (Fraser et al., 2019; McCook et al., 2010; Westera et al., 2003). Elasmobranchs are also at risk in multipleuse marine parks. In the Great Barrier Reef MPA, various elasmobranch species continue to be caught in the Queensland East Coast Inshore Finfish Fishery (Harry et al., 2011) as well as by recreational fishers (Lynch et al., 2010). There are no commercial shark fisheries operating in the Ningaloo area of Western Australia, but elasmobranchs are still caught as bycatch in other commercial fisheries, and are targeted by recreational fishers (CALM and MPRA, 2005). It is thus not surprising that the de facto Wandoo MPA is supporting higher numbers of threatened elasmobranchs than areas that remain open to fishing despite their MPA status. Active oil fields in NW Australia, like Wandoo, may be important refuges from fishing pressure for threatened elasmobranchs. Apart from limited recreational fishing from some platforms, all other fishing activity is excluded within the 500 m petroleum safety zone around platforms, and vessels are advised to avoid the larger 2.5 nautical mile to 5 nautical mile cautionary zones (Commonwealth of Australia, 2010). There are around 133 Ch 5: Threatened elasmobranchs 60 platforms in this region, effectively creating a network of highly protected de facto MPAs. These de facto MPAs meet four of the five criteria for effective MPAs (Edgar et al., 2014): they are no-take, or only permit a small amount of recreational fishing; they are well enforced due to the prescribed petroleum safety zones (Commonwealth of Australia, 2010); they are old, as almost half of the offshore platforms in NW Australia have been in place for more than 20 years (Geoscience Australia, 2009); and they are isolated, with most platforms being at least 50 km from nearest port (Geoscience Australia, 2009). Pipelines are not protected by petroleum safety zones, but represent physical obstacles to seabed trawling (de Groot, 1982). Threatened elasmobranchs have been found associated with both platforms and pipelines in NW Australia, including silvertip sharks, whale sharks, grey nurse sharks, and oceanic manta rays Mobula birostris (Bond et al., 2018b; McLean et al., 2018b, 2019; Todd et al., 2020a). Spillover from these de facto MPAs may also drive increased abundance of threatened elasmobranchs in surrounding natural habitats. Australian legislation currently stipulates that when offshore platforms reach the end of their productive lives, they must be completely removed from the marine environment. However, this legislation is currently under review to potentially allow for in situ decommissioning options (Offshore Resources Branch, 2018; Taylor, 2020). Many of the offshore platforms in the NW region have been in place for decades, and removing them would result in the loss of complex novel ecosystems (van Elden et al. in prep.; Pradella et al. 2014). Furthermore, the de facto MPAs that exclude fishing around platforms would be lost. The importance of these platforms to threatened elasmobranchs should be a consideration in future decommissioning decision-making, as well as decisions around allowing fishing at decommissioned platforms. Continuing to exclude fishing at offshore platforms post-decommissioning would maintain a network of highly protected de facto MPAs across NW Australia that would also contribute to Australia’s international commitments (Convention on Biological Diversity, 2020). The Wandoo field is a refuge for elasmobranchs vulnerable to seabed trawling activity and creates spillover of these species into natural habitats. Offshore platforms 134 Ch 5: Threatened elasmobranchs function as artificial reefs as well as FADs (Franks, 2000; Shinn, 1974), and Wandoo could therefore provide enhanced foraging opportunity for threatened elasmobranchs in the region. Parts of NW Australia are considered hotspots for endangered elasmobranchs, and the region has globally significant populations of threatened species (Anon., 2018; Morgan et al., 2011). 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Pearson Education India. 142 Ch 5: Threatened elasmobranchs 5.7 SUPPLEMENTARY INFORMATION Supplementary Figure 5.2 Schematics of (a) seabed and (b) mid-water stereo- 143 Ch 5: Threatened elasmobranchs Supplementary Table 5.1 Demersal regions and locations, including average coordinates for each location (decimal degrees), years in which the locations were surveyed, and number of surveys per location. Bolded text indicates the regions, with the locations listed below each region. Location Northeast East Cape York - North East Cape York - Middle East Cape York - South Ribbons - North Ribbons - Central Ribbons - South Torres Strait - East Torres Strait - West Cocos-Keeling Islands Cocos Island Northwest Adele Island Ashmore Reef Barrow Island Dampier Archipelago Holothuria Reef Long Reef Rowley Shoals Wandoo Wandoo Platform Wandoo Sand Wandoo Reef Central North Ningaloo Reef - North Ningaloo Reef - Middle Ningaloo Reef - South Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - South Passage Shark Bay - Steep Point Latitude (°S) Longitude (°E) Survey Years No. of Surveys 11.5 12.2 14.1 11.3 13.7 14.4 10.1 9.9 143 143.2 144.2 143.7 143.8 144.8 143.6 143.3 2017, 2018 2017, 2018 2017 2017,2018 2017,2018 2017,2018 2017 2017 3 3 1 2 3 2 2 1 12.1 96.9 2016 1 15.6 12.2 20.8 20.5 13.6 13.9 17.2 123.2 123 115.5 116.7 126 125.7 119.5 2017 2017 2008-2010 2008 2017 2017 2017 1 1 3 1 1 1 1 20.1 20.1 20.1 116.4 116.6 116.2 2017-2019 2018, 2019 2017-2019 6 3 4 22.1 22.7 23.8 113.8 113.6 113.3 2006, 2007, 2009 2006, 2009 2009 3 2 1 26 25.5 26.1 26.3 113.1 113.2 113.2 113.3 2017, 2018 2009 2018 2017, 2018 2 1 1 2 144 Ch 5: Threatened elasmobranchs Supplementary Table 5.2 Pelagic regions and locations, including average coordinates for each location, years in which the locations were surveyed, and number of surveys per location. Bolded text indicates the regions, with the locations listed below each region. Location Northeast Great Barrier Reef Cocos-Keeling Islands Cocos Island Northwest Ashmore Reef - North Ashmore Reef - South Long Reef - East Long Reef - West Montebello Islands Montebellos Islands - Offshore Muiron Islands Rowley Shoals Rowleys Shoals - Offshore Wandoo Wandoo Platform Wandoo Sand Wandoo Reef Central North Ningaloo Reef - Offshore Ningaloo Reef Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - Steep Point No. of Surveys Latitude (°S) Longitude (°E) Survey Years -11.2 143.2 2017 2 -12.1 96.8 2016 1 -12.2 -12.2 -13.9 -13.8 -20.3 -19.9 -21.6 -17.1 -15.4 123.1 123.1 125.9 125.6 115.4 115.4 114.2 119.4 118.5 2017 2018 2017; 2018 2017; 2018 2018 2018 2018; 2019 2017 2017; 2018 1 1 2 2 1 1 2 1 2 -20.1 -20.1 -20.1 116.4 116.6 116.2 2017; 2018; 2019 2018; 2019 2017; 2018 2019 6 3 4 -21.8 -21.9 113.5 113.8 2016 2016; 2018; 2019 1 3 -26.0 -26.1 -26.3 113 113.2 113.1 2017; 2018; 2019 2012 2012; 2017; 2018; 2019 3 1 4 145 Supplementary Table 5.3 Environmental and anthropogenic variables for locations sampled with seabed stereo-BRUVS. Variables include: distance to port (DistPort); distance to coast (DistCoast); dissolved oxygen (O2); salinity (Sal); sea surface temperature (SST); and depth. Bolded text indicates the regions, with the locations listed below each region. Distance to market and population were computed using the LandScan 2016 database (Dobson et al., 2000), while distances to marine features were computed using bathymetry data (Yesson et al., 2020). Environmental data were derived from: Geoscience Australia (GA) 250 m bathymetry (Whiteway, 2009); GA Australian submarine canyons (Huang et al., 2014); CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020) distPort (km) distCoast (km) Sal (psu) O2 (mmol/L) SST (°C) Depth (m) 35 72.5 93.9 61.9 88.5 71.3 89.3 77 1.6 5.6 1.9 7.5 53.7 5.2 26.2 1.1 4.2 4.2 4.1 4.2 4.2 4.3 4.2 4.2 35 35.7 35.1 35 35.1 35.1 35.1 35.1 27.3 28 27.7 27.6 27.1 27.5 27.5 26.4 7.8 8.7 9.1 8 9.7 9.4 10.3 11.5 11.1 1.9 4.4 34.4 27.7 5.3 45.3 242 52.6 12.3 242.7 220.3 169.3 6 321.4 6.5 3.4 25.3 13.2 264 4.3 4.4 4.5 4.4 4.3 4.3 4.5 34.8 34.5 35.2 35.4 34.8 34.8 34.7 26.8 27.1 27.7 21.9 26.2 25.9 28.5 6.4 10 9.4 15.7 3.1 9.4 9 36 36.2 42.4 40.2 38.4 50.8 4.5 4.5 4.5 35.2 35.2 35.2 26.3 27.6 26.5 52 54.8 51.8 Ch 5: Threatened elasmobranchs 146 Location Northeast East Cape York - North East Cape York - Middle East Cape York - South Ribbons - North Ribbons - Central Ribbons - South Torres Strait - East Torres Strait - West Cocos-Keeling Islands Cocos Island Northwest Adele Island Ashmore Reef Barrow Island Dampier Archipelago Holothuria Reef Long Reef Rowley Shoals Wandoo Wandoo Platform Wandoo Sand Wandoo Reef Central North Ningaloo Reef - North Ningaloo Reef - Middle Ningaloo Reef - South Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - South Passage Shark Bay - Steep Point 60.1 28.1 27.6 9.9 2.9 22.4 4.7 4.6 4.6 35.1 35 35.3 26.9 25.1 26.4 64.8 20.5 67.6 34.4 5.7 12.6 18.2 0.4 15.3 0.8 0.6 4.8 4.8 4.8 4.7 35.3 35.3 35.3 35.5 21 19.7 20.6 21 18.6 4.9 4.9 26.3 Supplementary Table 5.4 Environmental and anthropogenic variables for locations sampled with midwater stereo-BRUVS. Variables include: linear distance to cities (LinDistCities); travel time to market (TravelTime_market); time to nearest population (TravelTime_pop); linear distance to nearest population (LinDistPop); distance to port (DistPort); distance to seamounts (DistSeamounts); distance to coral reef (DistCoralReef); depth; slope; distance to coast (DistCoast); chlorophyll concentration (Chl); and sea surface temperature (SST). Bolded text indicates the regions, with the locations listed below each region. Distance to market and population were computed using the LandScan 2016 database (Dobson et al., 2000), while distances to marine features were computed using bathymetry data (Yesson et al., 2020). Environmental data were derived from: Geoscience Australia (GA) 250 m bathymetry (Whiteway, 2009); GA Australian submarine canyons (Huang et al., 2014); CSIRO Atlas of Regional Seas (CARS) (Ridgway et al., 2002); and Australia’s Integrated Marine Observing System (IMOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (IMOS, 2020) LinDistcities (km) TravelTime_market (mins) TravelTime_pop (mins) LinDistpop (km) distPort (km) 267 812 72 22.9 144 10 51 17 5.2 11.1 260 261 509 498 1,339 1,369 821 826 1,526 817 4,017 4,107 31 33 33 57 101 220 9.8 10.3 10.4 18.2 32.3 69.3 185 184 280 249 30.8 29.9 147 Ch 5: Threatened elasmobranchs Location Northeast Great Barrier Reef Cocos-Keeling Islands Cocos Island Northwest Ashmore Reef - North Ashmore Reef - South Long Reef - East Long Reef - West Montebello Islands Montebellos Islands - Offshore Muiron Islands Rowley Shoals Rowleys Shoals - Offshore Wandoo Wandoo Platform Wandoo Sand Wandoo Reef Central North Ningaloo Reef - Offshore Ningaloo Reef Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - Steep Point 1,190 948 812 3,569 2,845 2,436 36 83 778 11.7 26.3 241 15.3 296 470 1,358 1,366 1,355 4,073 4,099 4,064 134.4 125.6 154 41.5 39 49.4 36 36.2 42.4 1,181 1,163 3,543 3,490 165.6 47.4 52.2 15.2 70.9 36.1 727 701.3 686.7 2,181 2,104 2,060 31.4 1.9 30.9 10 0.8 9.9 34.4 5.7 18.2 Ch 5: Threatened elasmobranchs 148 Supplementary Table 5.4 (Cont.) distSeamounts (km) distCoralReef (km) Depth (m) Slope distCoast (km) Chl (mg/m3) SST (°C) 442.5 2.8 37 89.7 21 0.4 27.5 37.5 2.9 1,149 90 3.8 0.2 27.8 99.6 99.8 408.7 379 445 6.2 6.6 7.3 9.4 31.7 208.2 222.2 42 48.6 68.6 90 90 89.7 89.4 89.6 10.4 10.9 11 18.7 32.9 0.2 0.2 0.6 0.4 0.3 29.4 29.4 29.2 29.4 26.9 405.2 373.2 269.5 87 69.2 9.8 11.9 221.5 380.7 86.3 434.1 4,840 89.6 89.9 89.9 90 69.8 12 259.6 339.8 0.2 0.4 0.1 0.1 27.3 26.1 28.6 29 468.6 466.5 466.1 41.4 45.7 50.8 50 53.3 51.3 89.5 83.6 88.5 41.5 39.2 49.8 0.3 0.3 0.3 27.2 27.2 27.1 304 340.3 50.6 13.2 1,464 499.1 90 90 52.9 15.8 0.2 0.3 26.1 26 470.7 496.5 479.8 8.1 9.3 25.3 91.9 11.5 99.4 89.7 89.8 89.7 10.6 1 10.5 0.3 1 0.4 23.4 23.1 23.3 149 Ch 5: Threatened elasmobranchs Location Northeast Great Barrier Reef Cocos-Keeling Islands Cocos Island Northwest Ashmore Reef - North Ashmore Reef - South Long Reef - East Long Reef - West Montebello Islands Montebellos Islands Offshore Muiron Islands Rowley Shoals Rowleys Shoals - Offshore Wandoo Wandoo Platform Wandoo Sand Wandoo Reef Central North Ningaloo Reef - Offshore Ningaloo Reef Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - Steep Point Supplementary Table 5.5 List of threatened elasmobranchs recorded on seabed stereo-BRUVS by location, including their IUCN Red List classifications (IUCN): Vulnerable (VU); Endangered (EN) and Critically Endangered (CR). The regions are Northeast (NE), Cocos-Keeling Islands (CI), Northwest (NW), Wandoo (WN), Central North (CN) and Central South (CS). Bolded text indicates the regions, with the locations listed below each region. Binomial Aetobatus ocellatus Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Negaprion acutidens Himantura sp. Himantura uarnak Himantura undulata Pateobatis fai Pateobatis jenkinsii Taeniurops meyeni Urogymnus granulatus Nebrius ferrugineus Glaucostegus typus Hemipristis elongata Mobula alfredi Mobula thurstoni Mobula birostris Carcharias taurus Pristis clavata Rhina ancylostoma Rhynchobatus sp. IUCN VU VU VU VU EN VU VU VU VU VU VU VU VU VU VU VU CR VU VU EN VU VU EN CR CR East Cape York - Middle X X X X X X X X X X X X X Ribbons - North X X Ribbons - Central Ribbons - South Torres Strait - East Torres Strait - West CI Cocos Island X X X X X X X X X X X X X X X X X X X X X X 150 Ch 5: Threatened elasmobranchs Family Aetobatidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Ginglymostomatidae Glaucostegidae Hemigaleidae Mobulidae Mobulidae Myliobatidae Odontaspididae Pristidae Rhinidae Rhinidae NE East Cape York - North Sphyrnidae Sphyrnidae Stegostomatidae Sphyrna lewini Sphyrna mokarran Stegostoma tigrinum CR CR EN X X X X X X X X Supplementary Table 5.5 (Cont.) Binomial Aetobatus ocellatus Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Negaprion acutidens Himantura sp. Himantura uarnak Himantura undulata Pateobatis fai Pateobatis jenkinsii Taeniurops meyeni Urogymnus granulatus Nebrius ferrugineus Glaucostegus typus Hemipristis elongata Mobula alfredi Mobula thurstoni Mobula birostris Carcharias taurus Pristis clavata IUCN VU VU VU VU EN VU VU VU VU VU VU VU VU VU VU VU CR VU VU EN VU VU EN Barrow Island Dampier Archipelago Holothuria Reef Long Reef X Rowley Shoals WN Wandoo Platform Wandoo Sand Wandoo Reef X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Ch 5: Threatened elasmobranchs 151 Family Aetobatidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Ginglymostomatidae Glaucostegidae Hemigaleidae Mobulidae Mobulidae Myliobatidae Odontaspididae Pristidae NW Ashmore Reef Rhinidae Rhinidae Sphyrnidae Sphyrnidae Stegostomatidae Rhina ancylostoma Rhynchobatus sp. Sphyrna lewini Sphyrna mokarran Stegostoma tigrinum CR CR CR CR EN X X X X X X X X X X X X X X X X X X X X X X X X X X X Supplementary Table 5.5 (Cont.) CN Binomial Aetobatus ocellatus Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Negaprion acutidens Himantura sp. Himantura uarnak Himantura undulata Pateobatis fai Pateobatis jenkinsii Taeniurops meyeni Urogymnus granulatus Nebrius ferrugineus Glaucostegus typus Hemipristis elongata Mobula alfredi Mobula thurstoni IUCN VU VU VU VU EN VU VU VU VU VU VU VU VU VU VU VU CR VU VU EN Ningaloo - North Ningaloo - Middle Ningaloo - South Shark Bay - Gulf Shark Bay South Passage Shark Bay Steep Point X X X X X X X X X X X X X X X X X X X X X X X Ch 5: Threatened elasmobranchs 152 Family Aetobatidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Dasyatidae Ginglymostomatidae Glaucostegidae Hemigaleidae Mobulidae Mobulidae CS Shark Bay Dirk Hartog Island Myliobatidae Odontaspididae Pristidae Rhinidae Rhinidae Sphyrnidae Sphyrnidae Stegostomatidae Mobula birostris Carcharias taurus Pristis clavata Rhina ancylostoma Rhynchobatus sp. Sphyrna lewini Sphyrna mokarran Stegostoma tigrinum VU VU EN CR CR CR CR EN X X X X X X X X X X X Supplementary Table 5.6 List of threatened elasmobranchs recorded on midwater stereo-BRUVS by location, including their IUCN Red List classification (IUCN)s: Vulnerable (VU); Endangered (EN) and Critically Endangered (CR). The regions are Northeast (NE), Cocos (Keeling) Islands (CI), Northwest (NW), Wandoo (WN), Central North (CN) and Central South (CS). Bolded text indicates the regions, with the locations listed below each region. Binomial Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus longimanus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Isurus oxyrinchus Mobula birostris Mobula sp. Negaprion acutidens Rhincodon typus Sphyrna lewini Sphyrna mokarran IUCN VU VU VU CR EN VU VU EN VU VU VU EN CR CR CI Cocos Island NW Ashmore Reef - North X X Ashmore Reef -South Long Reef - East Long Reef - West X X X X X X X X X X X X Montebello Islands X X X X X X X X X X X X X X X X 153 Ch 5: Threatened elasmobranchs Family Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Lamnidae Myliobatidae Myliobatidae Carcharhinidae Rhincodontidae Sphyrnidae Sphyrnidae NE Great Barrier Reef X Supplementary Table 5.6 (Cont.) Binomial Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus longimanus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Isurus oxyrinchus Mobula birostris Mobula sp. Negaprion acutidens Rhincodon typus Sphyrna lewini Sphyrna mokarran IUCN VU VU VU CR EN VU VU EN VU VU VU EN CR CR Muiron Islands X X WN X X X X X X X X CN Rowley Shoals Wandoo Platform X Wandoo Sand Wandoo Reef X X X X X X X X X X X X X X Ningaloo Reef - Offshore Ningaloo Reef X X X X X X X X X X X X X X X 154 Ch 5: Threatened elasmobranchs Family Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Lamnidae Myliobatidae Myliobatidae Carcharhinidae Rhincodontidae Sphyrnidae Sphyrnidae NW Montebello Islands Offshore Supplementary Table 5.6 (Cont.) Family Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Carcharhinidae Lamnidae Myliobatidae Myliobatidae Carcharhinidae Rhincodontidae Sphyrnidae Sphyrnidae Binomial Carcharhinidae sp. Carcharhinus albimarginatus Carcharhinus falciformis Carcharhinus longimanus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sp. Isurus oxyrinchus Mobula birostris Mobula sp. Negaprion acutidens Rhincodon typus Sphyrna lewini Sphyrna mokarran IUCN VU VU VU CR EN VU VU EN VU VU VU EN CR CR CS Shark Bay - Dirk Hartog Island Shark Bay Gulf X Shark Bay Steep Point X X X X X X X X X X X Ch 5: Threatened elasmobranchs 155 Ch 6: General Discussion CHAPTER 6 GENERAL DISCUSSION The world’s oceans are being industrialised at an unprecedented rate in what is being called a marine industrial revolution (Salcido, 2008; Wright, 2015). The major sectors of ocean industrialisation are mineral and energy resources, transport and communication, leisure, and coastal engineering (Smith, 2000). Increases in global energy consumption, along with advances in technology, have driven offshore energy exploration and production on a global scale. The first offshore oil and gas platform (offshore platform) was installed in 1947, and the industry has subsequently grown rapidly to an estimated 12,000 offshore platforms in 2017 (Aagard and Besse, 1973; Ars and Rios, 2017). Offshore platforms around the world create diverse and productive marine ecosystems. These platforms may play important ecological roles, including increasing hard substrate on regional scales, providing habitat for juvenile fish species, and functioning as de facto marine protected areas (MPAs) (Friedlander et al., 2014; Love et al., 2006; Schroeder and Love, 2004). The novel ecosystem concept (Hobbs et al., 2013b) has only recently been used to describe the ecosystems that emerge around offshore platforms, and contributes to decision-making around the decommissioning process. Australia’s tropical marine regions are vast and diverse (Lough, 2008). Many of these regions are impacted by increasing ocean industrialisation despite the implementation of networks of multiple-use MPAs (Parks Australia 2020). Australia’s Northwest Shelf (NWS) is a marine biodiversity hotspot that is also rich oil and gas (O&G) reserves. The offshore infrastructure in this region includes over 60 platforms and thousands of kilometres of pipeline, which are inhabited by endangered megafauna and commercially important fish species (Bond et al., 2018b; McLean et al., 2019; Pradella et al., 2014). The offshore platforms on the NWS are potentially regionally important ecosystems given the area is generally characterised by sandy habitats with little hard substrate and low habitat complexity. Industry-funded independent research provides insight not only into the marine communities associated with these platforms, but also into the ecology of this largely understudied biodiversity hotspot. 156 Ch 6: General Discussion This dissertation has two emergent themes: Offshore platforms as novel ecosystems. The novel ecosystem concept can be applied to offshore platforms on a case-by-case basis, and more generally, can be integrated into existing decommissioning analysis frameworks. The Wandoo platform was treated as a first case study for the novel ecosystem concept and the associated ecosystem was found to be significantly altered from what prevailed historically. The marine communities at Wandoo are distinct from those found at natural habitats, with diverse, reef-associated demersal fishes characterising the platform-associated community. The Wandoo field also functions as a de facto MPA allowing macrobenthos communities to recover from historical trawling, and provides a refuge for threatened elasmobranchs. The use of stereo-BRUVS to study offshore platform-associated communities. StereoBRUVS have only been used in a handful of studies on the ecology of offshore platform to date. Rare and highly mobile species, as well as novel behaviours, are reported from the stereo-BRUVS deployed around the Wandoo field. Stereo-BRUVS can effectively sample the ecological halo created by offshore platforms, and allow platformassociated communities to be compared with other habitats sampled with BRUVS on regional, national and international scales. The combined use of both seabed and midwater stereo-BRUVS allows for effective sampling of offshore platform habitats that extend from the seafloor to the surface. The ability to cost-effectively and safely obtain large quantities of video data, and without the influence of human presence, means that stereo-BRUVS are an effective tool for recording ecological data around offshore platforms. 6.1 SYNERGY AMONGST CHAPTERS This dissertation provides insight into how the installation of offshore platforms can result in the emergence of novel ecosystems. There is synergy among these chapters on several themes, with all four data chapters providing insight into the novel marine communities found around offshore platforms. In chapters 2 and 3, I explicitly evaluate offshore platforms as novel ecosystems. Chapters 3 to 5 describe the ecology of the Wandoo oil field in both a local and regional context, and provide evidence for the advantages of using stereo-BRUVS to study offshore platform-associated communities. 157 Ch 6: General Discussion Offshore platforms as novel ecosystems In chapters 2 and 3 of this dissertation, I tested the application of the novel ecosystem concept to offshore platforms using a combination of a literature review (Chapter 2) and a field-based case study (Chapter 3). At face value, offshore platforms appear to be ideal candidates for classification as novel ecosystems, however prudence is necessary when combining these two contentious subjects. Offshore platforms and Rigs-to-Reefs (RTR) have faced significant public criticism, particularly in the cases of the Brent Spar (Löfstedt and Renn, 1997) and public opposition in California (Schroeder and Love, 2004). In contrast, criticisms of the novel ecosystem concept have predominantly come from the scientific community (Murcia et al., 2014; Simberloff et al., 2015). Classifying offshore platforms as novel ecosystems could potentially be viewed as simply an excuse for energy companies to dump unwanted platforms at sea, minimising costs associated with their end-of-life decommissioning. It is therefore crucial that the application of the novel ecosystem concept to offshore platforms is backed by solid scientific evidence. In Chapter 2 (van Elden et al., 2019), I demonstrate that the novel ecosystem concept can be applied to offshore platforms and can be incorporated into existing decommissioning frameworks. I developed three criteria for applying the novel ecosystem concept to offshore platforms, based on its most recent definition (Hobbs et al., 2013a). These criteria cover various aspects of offshore platform ecology and decommissioning, including ecosystem alteration, the lack of human management of the ecosystems, and considerations preventing the ecosystem from being restored with respect to ecological, environmental and social factors. The criteria are often context-specific, and should therefore be applied to platforms on a case-by-case basis. However, existing decommissioning decision analysis frameworks can be adapted to incorporate the novel ecosystem criteria, alongside typical decommissioning considerations such as water quality, social opposition to the platform, marine communities, and financial cost (Fowler et al., 2014; Henrion et al., 2015) for a more generalised approach. In Chapter 3, I applied the criteria developed in Chapter 2 to the Wandoo oil field on Australia’s NWS. I found that the Wandoo field has been ecologically altered by the presence of infrastructure, and that the self-organising ecosystem at Wandoo has 158 Ch 6: General Discussion novel qualities that would not have been present historically. The study of the marine communities in the Wandoo field assessed demersal and pelagic communities as well as habitat composition, all of which are impacted by the presence of offshore infrastructure. A critical component of this case study was the identification of a site which resembled the reported historical state of the Wandoo field. Studying this site allowed me to infer what the marine communities would have looked like at Wandoo prior to the installation of infrastructure, and determine how these communities have changed over time. The assessment presented in Chapter 3 found that a novel ecosystem has emerged in the Wandoo field. Classifying Wandoo as a novel ecosystem provides a mechanism for recognising the various ecological roles played by the infrastructure in the Wandoo field, all of which should be considered in the decommissioning assessment process. This case study can be used as a template for applying the novel ecosystem criteria to other offshore platforms. Ecology of the Wandoo field The three year ecological study into the marine communities in the Wandoo field forms the basis of this dissertation. The outcomes of this study are presented in chapters 3 to 5, and provide insight into a diverse and important novel ecosystem which influences surrounding natural habitats. Chapter 2, in describing the ecological traits of offshore platforms around the world, provides context for the assessment of the Wandoo field as a novel ecosystem. In Chapter 3, I found that the marine community at Wandoo differs from those found at adjacent natural habitats. The seabed habitat at Wandoo was dominated by macrobenthos communities, whereas the two natural sites were dominated by bare sand habitats. The exclusion of seabed trawling around Wandoo has protected the macrobenthos communities, and allowed them to recover after decades of destructive seabed trawling activity in this region (Sainsbury et al., 1993). Both demersal and pelagic communities at Wandoo had shifted from their likely historical state: the demersal community was more diverse than the natural habitats and was characterised by reef-associated species not seen at the sandy site. Whilst the pelagic communities were more similar across the three sites than the demersal communities, the Wandoo pelagic community was characterised by species that are strongly 159 Ch 6: General Discussion ‘platform-associated’, namely rainbow runner Elagatis bipinnulata and great barracuda Sphyraena barracuda (Friedlander et al., 2014; McLean et al., 2019). In Chapter 4 (van Elden and Meeuwig, 2020), I report the first wild record of dynamic decapod mimicry by a cuttlefish. The cuttlefish, tentatively identified as Smith’s cuttlefish Sepia smithi, was observed approaching the bait bag while employing crustacean-like aggressive mimicry. This is the first wild observation of crustacean-like aggressive mimicry by a cuttlefish, and provides further evidence of the usefulness of stereo-BRUVS for studying animal behaviour. Stereo-BRUVS allow for remote sampling without human influence and have recorded a range of novel animal behaviours (Barley et al., 2016; Birt et al., 2019). In Chapter 5, I found that the abundance of threatened elasmobranchs in the Wandoo field and adjacent natural habitats was higher than that in most of Australia’s tropical regions, including locations in the Ningaloo Reef and Great Barrier Reef multiple-use MPAs. Several taxa were also found in higher abundance around the Wandoo field than in other regions, including silky sharks Carcharhinus falciformis, wedgefishes Rhynchobatus sp., and leopard sharks Stegostoma tigrinum. The Wandoo field is a de facto MPA, excluding the seabed trawl fishery operating in the region. This de facto MPA not only provides refuge for threatened elasmobranchs, but is also likely to increase their abundance in adjacent natural habitats through spillover as is generally the case for MPAs (Halpern et al., 2009; Roberts et al., 2001). Wandoo has several ecological traits that are characteristic of offshore platforms around the world. Wandoo functions as an artificial reef dominated by reef-associated species, and is also an important habitat for commercially important fish species and threatened elasmobranchs, as has been reported from other infrastructure on the NWS and elsewhere (Bond et al., 2018b; Love et al., 2006; McLean et al., 2019; Pradella et al., 2014; Robinson et al., 2013). The cuttlefish mimicry recorded at Wandoo (Chapter 4) adds to the literature on novel behavioural records near offshore infrastructure (Bond et al., 2020a; Haugen and Papastamatiou, 2019; Robinson et al., 2013). Many offshore platforms are located in remote, understudied regions such as Australia’s NWS. The collection of novel behavioural records at offshore platforms likely reflects the lack of research into the remote regions where these platforms are 160 Ch 6: General Discussion located. Increasing ecological research around offshore platforms may reveal more novel records and behaviours, and increase our knowledge of remote offshore ecosystems. The use of stereo-BRUVS to study offshore platform-associated communities Chapters 3 to 5 of this dissertation demonstrate the usefulness of stereo-BRUVS for studying offshore platform-associated communities. Stereo-BRUVS have only been used in a handful of ecological studies on offshore infrastructure to date (Bond et al., 2018b; Reynolds et al., 2018). Stereo-BRUVS are relatively inexpensive, particularly in comparison with other commonly used sampling methods such as remotely operated vehicles (ROVs; Letessier et al. 2015b). They can also be deployed over large spatial scales, which allows for sampling of the ecological halo created by offshore platforms as well as surrounding natural habitats, as demonstrated in Chapter 3. Stereo-BRUVS can be used to obtain a significant amount of data over a short period of time, which is advantageous for sampling offshore platforms located far from shore or in areas prone to severe weather conditions. The expeditions to the Wandoo field were restricted to about six to ten days, due to extreme tide ranges and unpredictable weather conditions. Despite this restriction on sampling time, an average of 250 hours of video data were collected on each of the six expeditions, sufficient to detect spatial and temporal differences between sites. Chapter 5 demonstrates how the use of stereo-BRUVS around Wandoo allows for comparisons with existing stereo-BRUVS data on a large scale. Comparing platformassociated communities with those found at natural habitats is an effective method for assessing the way these platforms alter regional ecology, and potentially create novel ecosystems. Stereo-BRUVS studies on offshore platforms allow for comparisons with data from nearby habitats, or from similar regions around the world. The increased use of stereo-BRUVS to study offshore platform communities would also allow for comparisons between platforms, which are lacking in regions such as Australia’s Northwest Shelf. Several studies have reported elusive animals or novel behaviours observed on stereoBRUVS imagery (Barley et al., 2016; Birt et al., 2019; Bond et al., 2018b; Letessier et al., 2015a; Thompson et al., 2019). Stereo-BRUVS allow us to spend significantly more time 161 Ch 6: General Discussion observing marine habitats and the wildlife therein, without the influence of human presence, and increase the likelihood of observing rare animals and behaviours. Chapter 4 reports a stereo-BRUVS observation of a behaviour not previously reported outside of a laboratory setting. Stereo-BRUVS enabled me to measure the mantle length of the cuttlefish, which significantly helped in obtaining a tentative species identification. Novel behaviours have been reported from offshore infrastructure in the past, including megafauna aggregations and pufferfish nests (Bond et al., 2020a; Haugen and Papastamatiou, 2019; Robinson et al., 2013). Stereo-BRUVS deployed around offshore infrastructure are likely to observe more of these rare species and novel behaviours in future. These novel records and behaviours provide insight into understudied ecosystems and increase our understanding of complex animal behaviours and interactions. 6.2 CAVEATS AND FUTURE DIRECTIONS This dissertation demonstrates the effectiveness of stereo-BRUVS in obtaining large quantities of data over a large spatial scale, which is useful when documenting the status of communities associated with offshore platforms. The six expeditions to Wandoo and adjacent natural habitats yielded over 1,600 hours of video footage from 595 seabed and 530 mid-water stereo-BRUVS deployments. In analysing the video imagery, I counted 35,070 individual animals from 358 taxa, representing 85 families. One constraint on the data collection for this dissertation was the health and safety restrictions on sampling around infrastructure. Stereo-BRUVS had to be deployed at least 50 m away from all infrastructure to avoid possible entanglement or damage. This sampling constraint was mitigated by sampling 50 m away from the reef at the Control Reef site, which allowed for like-for-like comparisons between the sites. An unexpected positive outcome of this sampling constraint was the discovery of a large ecological halo around the Wandoo infrastructure, with elevated fish diversity and denser macrobenthos habitat. The ecological halo around Wandoo also appears to be larger than previous reports of ecological halos around offshore platforms. It would nevertheless be beneficial to obtain comparable data on the communities residing directly on the infrastructure. ROVs have previously been used to assess these communities (Tothill, 2019) and in Appendix 1 (van Elden at al. 2020) I used these ROV data, along with the BRUVS data obtained from Wandoo, to demonstrate that a 162 Ch 6: General Discussion combination of these two methods allows for complete sampling of an offshore platform and the surrounding ecological halo. However, with no ROV data from the two control sites in this study, I could not compare the communities at Wandoo with those found on the natural reef site. A combination of sampling methods, such as SCUBA diver surveys and ROVs, has been used to survey platform-associated communities in other regions (Ajemian et al., 2015; Bond et al., 2020b; Love et al., 1994) and future studies could involve a combination of ROVs and BRUVS surveys at both offshore platforms and natural habitats. The novel ecosystem that has emerged in the Wandoo field has likely impacted a range of marine taxa beyond those assessed in this dissertation. The roles Wandoo plays for these taxa need to be assessed before Wandoo is decommissioned. Benthic communities attached to the infrastructure were observed in abundance on archival ROV footage from Wandoo, and should be assessed. The presence of hard substrate extending to the surface is not found in natural habitats, where the hard substrate is more than 30 m deep and there is less available light. The benthic species that have colonised the Wandoo infrastructure are therefore likely to be different from those found in natural habitats. During field work, I observed marine megafauna in close proximity to the platform, including reef mantas Mobula alfredi, humpback whales Megaptera novaeangliae and flatback turtles Natator depressus. These species are frequently observed both from the platforms and from vessels operating in the Wandoo field. Wandoo may serve an important ecological function for these animals, however their presence around the infrastructure needs to be quantified. Platform-based observations have been successfully used to record megafauna around offshore platforms in the North Sea, and could be implemented at Wandoo (Todd et al., 2016). A variety of seabirds have also been observed on the Wandoo infrastructure. Offshore platforms attract seabirds through the provision of roosting sites and shelter from severe weather, as well as enhanced feeding opportunity (Tasker et al., 1986). The decommissioning of Wandoo could have significant impacts for these birds, as the offshore platforms in the area represent the only roosting sites for a considerable distance. The seabird populations could also be assessed through platform-based observations, and the existing stereo- 163 Ch 6: General Discussion BRUVS database can be used to determine whether the prey species of these birds are found in abundance at Wandoo. 6.3 IMPLICATIONS FOR DECOMMISSIONING The novel ecosystem criteria developed in Chapter 2 provide a mechanism for recognising the ecological roles played by offshore platforms, and can complement current decommissioning decision analysis tools. I applied these criteria to the Wandoo field in Chapter 3, and concluded that a novel ecosystem has emerged due to the presence of the Wandoo infrastructure. I found that many of the positive novel qualities present at Wandoo would be lost under either ‘topping’ or ‘complete removal’ decommissioning scenarios. The mid-water portions are important for juvenile fishes and may act as FADs for pelagic fauna (Franks, 2000; Tothill, 2019), while the lower portions of the structures exclude seabed trawling and protect important macrobenthos habitat (Culwell, 1997). The exclusion of fishing in the Wandoo field has created a de facto MPA. This de facto MPA not only provides refuge for threatened elasmobranchs, but is also likely to increase their abundance in adjacent natural habitats through spillover. It is likely that the Wandoo field, along with the other offshore infrastructure on the NWS, is providing important habitat and refuge for threatened elasmobranchs in this marine biodiversity hotspot. The de facto MPA at Wandoo has several features of highly effective MPAs, and may be more effective than many multiple-use MPAs in Australia’s tropical regions (Edgar et al., 2014). It is likely that the petroleum safety zone around the Wandoo infrastructure would cease to exist post-decommissioning, which would expose much of the Wandoo field to commercial and recreational fishing. Maintaining an exclusion zone around the infrastructure would allow Wandoo to continue functioning as a de facto MPA, which should be an important consideration under any decommissioning scenario. The best ecological outcome for the decommissioning of Wandoo would involve the two platforms, Wandoo A and Wandoo B, being left standing in place. This scenario would maintain the roles Wandoo plays as an artificial reef and a FAD. The exclusion zone around the Wandoo infrastructure should be maintained in order to exclude both recreational and commercial fishing activity around the decommissioned 164 Ch 6: General Discussion infrastructure. This exclusion zone would ensure the protection of the ecological halo around the infrastructure, and maintain the de facto MPA that has been in place for decades. It is likely that this outcome would not only maintain the novel ecosystem that has emerged at Wandoo, but also enhance regional productivity through spillover from the MPA. 6.4 CONCLUSION Ocean industrialisation, driven by the insatiable demands of an increasing human population, is altering marine habitats and degrading the oceans (Salcido, 2008; Smith, 2000; Wright, 2015). Offshore energy production contributes a large percentage of global energy consumption, and has involved installing offshore platforms weighing thousands of tonnes, and thousands of kilometres of pipelines in the world’s oceans (OGP Decommissioning Committee, 2012; Planète Énergies, 2015). Offshore platforms create ecosystems that support a wide range of marine species from corals and sponges to fishes and marine megafauna (Gass and Roberts, 2006; Love et al., 2006; McLean et al., 2017; Todd et al., 2016). In this dissertation I have found that the installation of offshore platforms significantly alters the environment and ecology of the installation site, and creates an ecosystem with novel qualities not present pre-installation. In many cases, the ecosystem changes caused by the installation of offshore platforms result in the emergence of beneficial outcomes for marine communities. The novel ecosystem concept is a mechanism for recognising and managing these important habitats, but must be used prudently. I argue that a novel ecosystem has emerged in the Wandoo field, located in Australia’s NWS marine biodiversity hotspot. The presence of the Wandoo infrastructure has significantly altered the marine communities from those which would have existed previously, and these communities are distinct from those found in comparable natural habitats. The exclusion of fishing activity around Wandoo has resulted in a de facto MPA, allowing for the recovery of macrobenthos communities from historical trawling impacts, increased diversity of reef-associated fishes, and acting as a refuge for threatened elasmobranchs. The use of stereo-BRUVS has provided insight into various ecological aspects of the Wandoo platform, including rare and critically endangered fauna, novel animal behaviour, and diverse demersal and pelagic communities. I demonstrate that the combination of seabed and midwater stereo165 Ch 6: General Discussion BRUVS is an effective method for sampling the demersal and pelagic communities associated with offshore platforms, which are both impacted by the presence of infrastructure extending through the water column. This dissertation characterises the ecology of the novel ecosystem that has emerged in the Wandoo field, and presents strong ecological evidence for the Wandoo infrastructure to be maintained as an artificial reef, and protected as a MPA, post-decommissioning. 6.5 REFERENCES Aagard, P. M., and Besse, C. P. (1973). A Review of the offshore environment - 25 years of progress. J. Pet. Technol. 25, 1355–1360. Ajemian, M. J., Wetz, J. J., Shipley-Lozano, B., Dale Shively, J., and Stunz, G. W. (2015). An analysis of artificial reef fish community structure along the northwestern Gulf of Mexico Shelf: potential impacts of “rigs-to-reefs” programs. 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S., Schroeder, D. M., Lenarz, W., MacCall, A., Bull, A. S., and Thorsteinson, L. (2006). Potential use of offshore marine structures in rebuilding an overfished rockfish species, bocaccio (Sebastes paucispinis). Fish. Bull. 104, 383–390. McLean, D. L., Partridge, J. C., Bond, T., Birt, M. J., Bornt, K. R., and Langlois, T. J. (2017). Using industry ROV videos to assess fish associations with subsea pipelines. Cont. Shelf Res. 141, 76– 97. doi:10.1016/j.csr.2017.05.006. 167 Ch 6: General Discussion McLean, D. L., Taylor, M. D., Giraldo Ospina, A., and Partridge, J. C. (2019). An assessment of fish and marine growth associated with an oil and gas platform jacket using an augmented remotely operated vehicle. Cont. Shelf Res. 179, 66–84. doi:10.1016/j.csr.2019.04.006. Murcia, C., Aronson, J., Kattan, G. H., Moreno-Mateos, D., Dixon, K., and Simberloff, D. (2014). A critique of the “novel ecosystem” concept. Trends Ecol. Evol. 29, 548–553. doi:10.1016/j.tree.2014.07.006. OGP Decommissioning Committee (2012). Decommissioning of offshore concrete gravity based structures (CGBS) in the OSPAR maritime area/other global regions. 56. Parks Australia (2020). Australia Marine Parks. Available at: https://parksaustralia.gov.au/marine/parks/ [Accessed November 26, 2020]. Planète Énergies (2015). The challenges of oil and gas production. doi:10.5988/jime.50.633. Pradella, N., Fowler, A. M., Booth, D. J., and Macreadie, P. I. (2014). Fish assemblages associated with oil industry structures on the continental shelf of north-western Australia. J. Fish Biol. 84, 247–255. doi:10.1111/jfb.12274. Reynolds, E. M., Cowan Jr, J. H., Lewis, K. A., and Simonsen, K. A. (2018). Method for estimating relative abundance and species composition around oil and gas platforms in the northern Gulf of Mexico, U.S.A. Fish. Res. 201, 44–55. doi:10.1016/j.fishres.2018.01.002. Roberts, C. M., Bohnsack, J. A., Gell, F., Hawkins, J. P., and Goodridge, R. (2001). Effects of marine reserves on adjacent fisheries. Science (80-. ). 294, 1920–1923. doi:10.1126/science.294.5548.1920. Robinson, D. P., Jaidah, M. Y., Jabado, R. W., Lee-Brooks, K., Nour El-Din, N. M., Malki, A. A. Al, et al. (2013). Whale sharks, Rhincodon typus, aggregate around offshore platforms in Qatari waters of the Arabian Gulf to feed on fish spawn. PLoS One 8, e58255. doi:10.1371/journal.pone.0058255. Sainsbury, K. J., Campbell, R. A., and Whitelaw, A. W. (1993). “Effects of trawling on the marine habitat on the North West Shelf of Australia and implications for sustainable fisheries management.,” in Sustainable Fisheries Through Sustaining Fish Habitat. Australian Society for Fish Biology Workshop, ed. D. A. Hancock (Canberra: Australian Government Publishing Service), 137–145. Salcido, R. E. (2008). Offshore federalism and ocean industrialization. Tulane Law Rev. 82, 1355–1445. Schroeder, D. M., and Love, M. S. (2004). Ecological and political issues surrounding decommissioning of offshore oil facilities in the Southern California Bight. Ocean Coast. Manag. 47, 21–48. doi:10.1016/j.ocecoaman.2004.03.002. Simberloff, D., Murcia, C., and Aronson, J. (2015). “Novel ecosystems” are a Trojan horse for conservation. Available at: http://ensia.com/voices/novel-ecosystems-are-a-trojanhorse-forconservation/ [Accessed January 19, 2017]. Smith, H. D. (2000). The industrialisation of the world ocean. Ocean Coast. Manag. 43, 11–28. doi:10.1016/S0964-5691(00)00028-4. Tasker, M. L., Jones, P. H., Blake, B. F., Dixon, T. J., and Wallis, A. W. (1986). Seabirds associated with oil production platforms in the North Sea. Ringing Migr. 7, 7–14. doi:10.1080/03078698.1986.9673873. 168 Ch 6: General Discussion Thompson, C. D. H., Bouchet, P. J., and Meeuwig, J. J. (2019). First underwater sighting of Shepherd’s beaked whale (Tasmacetus shepherdi). Mar. Biodivers. Rec. 12, 1–6. doi:10.1186/s41200-019-0165-6. Todd, V. L. G., Warley, J. C., and Todd, I. B. (2016). Meals on wheels? A decade of megafaunal visual and acoustic observations from offshore oil & gas rigs and platforms in the North and Irish Seas. PLoS One 11. doi:10.1371/journal.pone.0153320. Tothill, T. (2019). The vertical distribution of fish species on two offshore oil platforms. van Elden, S., and Meeuwig, J. J. (2020). Wild observation of putative dynamic decapod mimicry by a cuttlefish (Sepia cf. smithi). Mar. Biodivers. 50, 93. doi:10.1007/s12526-02001117-0. van Elden, S., Meeuwig, J. J., Hobbs, R. J., and Hemmi, J. M. (2019). Offshore oil and gas platforms as novel ecosystems: a global perspective. Front. Mar. Sci. 6, Article 548. doi:10.3389/fmars.2019.00548. van Elden, S., Tothill, T., and Meeuwig, J. J. (2020). Strategies for obtaining ecological data to enhance decommissioning assessments. APPEA J. 60, 559–562. Wright, G. (2015). Marine governance in an industrialised ocean: a case study of the emerging marine renewable energy industry. Mar. Policy 52, 77–84. doi:10.1016/j.marpol.2014.10.021. 169 App 1: Obtaining ecological data on offshore platforms APPENDIX 1 STRATEGIES FOR OBTAINING ECOLOGICAL DATA TO ENHANCE DECOMMISSIONING ASSESSMENTS Sean van EldenA,B, Thomas TothillA, Jessica J. MeeuwigA ASchool of Biological Sciences, The University of Western Australia, Crawley, WA, Australia BCorresponding author. Email: sean.vanelden@research.uwa.edu.au; svanelden@gmail.com The APPEA Journal 2020, 60, 559–562 https://doi.org/10.1071/AJ19235 K EY W ORDS : D ECOMMISSIONING • P LATFORM ECOLOGY • ROV • BRUVS A1.1 ABSTRACT Many offshore oil and gas platforms around the globe are reaching their end-of-life and will require decommissioning in the next few decades. Knowledge on the ecology of offshore platforms and their ecological role within a regional context in Australia is limited and the subsequent consequences of decommissioning remain poorly understood. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however the utility of this video for scientific purposes remains unclear. We propose a standardised method of analysing this large database of archival ROV footage with specific interest in analysing the vertical distribution of fish species. Baited remote underwater video systems (BRUVS) are a widely used tool for studying marine faunal communities, and we demonstrate the value of BRUVS for understanding the regional ecology around offshore platforms. A combination of BRUVS and ROV data can be used to determine the relative ecological value of offshore platforms within a regional context. The Wandoo oil platform on Australia’s North West Shelf was used as a case study to test these proposed methods by assessing demersal and pelagic fish populations both on and around the Wandoo platform and various natural habitats in the region. A1.2 INTRODUCTION There are over 12,000 oil and gas platforms around the world, many of which have been in place for decades (Ars and Rios, 2017). Over this time, the sub-surface infrastructure of these platforms is colonised by sessile marine organisms such as algae, corals and sponges, which provide habitat and/or food for a variety of marine fauna (Forteath et al., 1982). Within about 5-6 years, offshore platforms can develop 170 App 1: Obtaining ecological data on offshore platforms reef-type communities and by the end of their lifespans, they have effectively become complex artificial reefs (Driessen, 1986a; Shinn, 1974). Some offshore platforms are among the most ecologically productive ecosystems globally (Claisse et al., 2014) and can become novel ecosystems, with unique species assemblages that were not present prior to the installation of the platform (van Elden et al., 2019). Legislation in most countries states that at the end of their lifespans, offshore platforms must be completely removed from the marine environment for onshore disposal. In many cases, this means the loss of a diverse and productive marine community. Understanding the ecological role played by offshore platforms should be a key part of the decommissioning process. Part of the challenge in understanding the potential ecological benefits of offshore platforms is the lack of data. Targeted ecological research is an expensive enterprise, however a wealth of ecological information is collected indirectly during standard industry operations, such as maintenance inspections on infrastructure and environmental surveys using remotely operated vehicles (ROV). The video footage collected during ROV surveys provide a previously un-utilised resource to ‘look back in time’ and assess ecosystem dynamics through a temporal lens (Macreadie et al., 2018), with archives often dating back to the original installation period. However, the ecological value of ROV video, which is often collected haphazardly, remains unclear. Industry ROV videos collected for inspection or other purposes need to be standardised prior to scientific evaluation. Several studies have utilised such ROV video for scientific purposes such as assessing marine algal and invertebrate growth (Gass and Roberts, 2006; Thomson et al., 2018; van der Stap et al., 2016) and the ecology of fish populations on and around offshore platforms (Pradella et al. 2014; McLean et al. 2018a) and pipelines (Bond et al., 2018a; McLean et al., 2017). All studies have implemented some form of standardisation of the video archives with varying degrees of success. Stereo baited remote underwater video systems (BRUVS) are a well-established method for studying the abundance, biomass and diversity of marine communities (Cappo et al. 2006). Stereo-BRUVS are a relatively inexpensive and non-destructive sampling method that can be deployed across large spatial scales (Letessier et al., 171 App 1: Obtaining ecological data on offshore platforms 2015b). While usually used to study demersal communities, stereo-BRUVS have more recently been adapted to sample mid-water environments (Bouchet et al., 2018a). A combination of benthic and mid-water stereo-BRUVS allows for the study of both demersal and pelagic marine faunal communities. Stereo-BRUVS are deployed in various marine environments around the world, according to standard operating procedures (see Bouchet et al. 2018; Langlois et al. 2018). While ROV’s and BRUVS have been used individually to study the ecology of offshore platforms, we propose using both sampling methods in tandem in order to gain a more complete understanding of the associated faunal communities. ROVs allow for targeted sampling of the infrastructure from the surface to the seafloor (McLean et al., 2018b) whilst BRUVS are useful for larger-scale sampling. In Australia, the 500 m exclusion zone around offshore infrastructure effectively constitutes a de facto Marine Protected Area (MPA) (Friedlander et al., 2014). BRUVS allow for sampling of the pelagic and demersal species in this extended area – often called the ecological halo (Reeds et al., 2018) – which is influenced by the presence of the offshore platforms. As a case study, we opportunistically utilised industry-collected ROV footage and conducted BRUVS surveys in the Wandoo oil field in north-west Australia, which is owned and operated by Vermillion Oil and Gas Australia. Wandoo is located on the north-west shelf of Australia, approximately 70 km offshore of Dampier, and consists of an unmanned monopod, Wandoo A, a four-shaft concrete gravity structure, Wandoo B, a Catenary Anchor Leg Mooring (CALM) Buoy, and associated subsea pipelines. Wandoo A and B were installed in 1993 and 1997 respectively and both sit in 54 m water depth. ROV videos of the Wandoo platforms were available for 2007, 2008, 2011 and 2015. The videos varied within and between each year depending on the task, ranging from broad environmental surveys to targeted inspections and cleaning protocols, resulting in highly variable and non-standardised video. Based on the analysis of the Wandoo ROV videos and previous studies utilising industry ROV, we propose a new method of selecting videos for ecological studies that involves a stringent scoring system adapted from Pradella et al. (2014), with specific interest given to assessing vertical distributions of fish species. Using this scoring system, videos deemed useful for 172 App 1: Obtaining ecological data on offshore platforms analysis must (1) follow the shaft or structure of interest in a distinct vertical transect, either descending or ascending, (2) have ≥ 5 m visibility, (3) be slow moving (<0.5 m/s, McLean et al. (2019)) to allow identification of fish species with no speed blur and (4) have the shaft/structure take up between 60-80% of the field of view (FOV). Figure A1.1 Stereo-BRUVS sampling sectors in the Wandoo Field. Due to the varying speed of transects, analysis of the subset of usable ROV video should be conducted using a frame-by-frame method. This involves stratifying each video transect into standardised depth categories (e.g. 0-10 m, 10-20 m etc.) and analysing a set of individual video frames (i.e. paused video at a selected depth) within each depth category for fish identification. Subsampling by frame reduces the risk of speed bias, whereby transects conducted at slower speeds may have a greater number 173 App 1: Obtaining ecological data on offshore platforms of fish visible. Following this method of selecting and analysing ROV footage may result in fewer videos being useful for analysis but will provide a more accurate representation of the fish communities that directly inhabit and associate with offshore infrastructure. To understand the extent of the ecological halo of the Wandoo platforms, seabed BRUVS were deployed with a stratified random distribution throughout the Wandoo Field, with particular focus on Wandoo A, Wandoo B and the CALM Buoy. Specifically, multiple sectors were established throughout the Wandoo Field with five deployments of seabed BRUVS within each sector (Figure 1). This allows full coverage of the area of interest and addresses safety concerns associated with sampling near the infrastructure. Mid-water BRUVS were deployed in a subset of the sectors as well as at four “remote” sectors at least 2 km from the outer boundary of the near-site sectors. This design helps determine how abundance declines with distance from a central feature. Expeditions were conducted twice per year over a period of three years, allowing for seasonal and inter-annual comparisons of fish assemblages. BRUVS were also deployed at two control sites: one being an area of natural “structure” of rocky substrate and similar spatial extent to the Wandoo infrastructure, and the other a flat, sandy area which is similar to what the Wandoo infrastructure was like prior to the installation of any subsea infrastructure. Both control sites are exposed to recreational and commercial fishing pressure, adding insight to the effect of the de facto MPA around Wandoo. Ecological studies on offshore platforms have previously focused on the infrastructure and immediate surrounds through use of industry ROV video. However, the ecological influence of these structures can extend far beyond the platform itself, particularly due to the de facto MPA created by the 500 m exclusion zone. BRUVS represent an efficient, inexpensive, and well-established method for sampling these larger areas which could be just as ecologically important as the platforms themselves. Using a combination of ROV and BRUVS surveys as outlined here allows for a more complete method of documenting the ecology of offshore oil and gas fields, which can better inform decommissioning decisions. 174 App 1: Obtaining ecological data on offshore platforms A1.3 ACKNOWLEDGEMENTS Our thanks to the Vermilion Oil and Gas Australia (Pty) Ltd. for their support of this project. A1.4 CONFLICT OF INTEREST This project is supported by Vermilion Oil and Gas Australia (Pty) Ltd., through the provision of ROV video archives and the VOGA Ph.D. Scholarship in Rigs-to-Reefs Ecology. A1.5 REFERENCES Ars, F & Rios, R (2017). Decommissioning: A call for a new approach, in 'Offshore Technology Conference', pp.1–7. Available from: http://www.onepetro.org/doi/10.4043/27717-MS. Bond, T, Langlois, TJ, Partridge, JC, Birt, MJ, Malseed, BE, Smith, L, & McLean, DL (2018). Diel shifts and habitat associations of fish assemblages on a subsea pipeline, Fisheries Research, 206, pp. 220–234. 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Offshore Oil Platforms: An Invaluable Ecological Resource, Oceans Conference Record (IEEE), pp. 516–521. van Elden, S, Meeuwig, JJ, Hobbs, RJ, & Hemmi, JM (2019). Offshore Oil and Gas Platforms as Novel Ecosystems: A Global Perspective, Frontiers in Marine Science, 6(548). Forteath, G, Picken, G, Ralph, R, & Williams, J (1982). Marine Growth Studies on the North Sea Oil Platform Montrose Alpha, Marine Ecology Progress Series, 8, pp. 61–68. Friedlander, AM, Ballesteros, E, Fay, M, & Sala, E (2014). Marine communities on oil platforms in Gabon, West Africa: High biodiversity oases in a low biodiversity environment, PLoS ONE, 9(8). Gass, SE & Roberts, JM (2006). The occurrence of the cold-water coral Lophelia pertusa (Scleractinia) on oil and gas platforms in the North Sea: Colony growth, recruitment and environmental controls on distribution, Marine Pollution Bulletin, 52(5), pp. 549–559. Langlois, TJ, Williams, J, Monk, J, Bouchet, PJ, Currey, L, Goetze, J, Harasti, D, Huveneers, C, Ierodiaconou, D, Malcolm, HA, & Whitmore, S (2018). Marine Sampling Field Manual for 175 App 1: Obtaining ecological data on offshore platforms Benthic Stereo BRUVS (Baited Remote Underwater Videos), in R Przeslawski & S Foster (eds), 'Field Manuals for Marine Sampling to Monitor Australian Waters', pp.82–104. National Environmental Science Program. Letessier, TB, Juhel, JB, Vigliola, L, & Meeuwig, JJ (2015). Low-cost small action cameras in stereo generates accurate underwater measurements of fish, Journal of Experimental Marine Biology and Ecology, 466, pp. 120–126. Available from: http://dx.doi.org/10.1016/j.jembe.2015.02.013. Macreadie, PI, McLean, DL, Thomson, PG, Partridge, JC, Jones, DOB, Gates, AR, Benfield, MC, Collin, SP, Booth, DJ, Smith, LL, Techera, E, Skropeta, D, Horton, T, Pattiaratchi, C, Bond, T, & Fowler, AM (2018). Eyes in the sea: Unlocking the mysteries of the ocean using industrial, remotely operated vehicles (ROVs), Science of the Total Environment, 634, pp. 1077–1091. McLean, DL, Macreadie, P, White, DJ, Thomson, PG, Fowler, A, Gates, AR, Benfield, M, Horton, T, Skropeta, D, Bond, T, Booth, DJ, Techera, E, Pattiaratchi, C, Collin, SP, Jones, DOB, Smith, L, & Partridge, JC (2018b). Understanding the Global Scientific Value of Industry ROV Data, to Quantify Marine Ecology and Guide Offshore Decommissioning Strategies, in, 'Offshore Technology Conference', p.10. McLean, DL, Partridge, JC, Bond, T, Birt, MJ, Bornt, KR, & Langlois, TJ (2017). Using industry ROV videos to assess fish associations with subsea pipelines, 'Continental Shelf Research', 141, pp. 76–97. Available from: http://dx.doi.org/10.1016/j.csr.2017.05.006. McLean, DL, Taylor, MD, Giraldo Ospina, A, & Partridge, JC (2019). An assessment of fish and marine growth associated with an oil and gas platform jacket using an augmented remotely operated vehicle, Continental Shelf Research, 179, pp. 66–84. Available from: https://doi.org/10.1016/j.csr.2019.04.006. McLean, DL, Taylor, MD, Partridge, JC, Gibbons, B, Langlois, TJ, Malseed, BE, Smith, LD, & Bond, T (2018a). Fish and habitats on wellhead infrastructure on the north west shelf of Western Australia, Continental Shelf Research, 164, pp. 10–27. Available from: https://doi.org/10.1016/j.csr.2018.05.007. Pradella, N, Fowler, AM, Booth, DJ, & Macreadie, PI (2014). Fish assemblages associated with oil industry structures on the continental shelf of north-western Australia, Journal of Fish Biology, 84(1), pp. 247–255. Reeds, KA, Smith, JA, Suthers, IM, & Johnston, EL (2018). An ecological halo surrounding a large offshore artificial reef: Sediments, infauna, and fish foraging, Marine Environmental Research, 141, pp. 30–38. Shinn, EA (1974). Oil structures as artificial reefs, in 'Proceedings of an international conference on artificial reefs', pp.91–96. van der Stap, T, Coolen, J, & Lindeboom, H (2016). Marine fouling assemblages on offshore gas platforms in the Southern North Sea: effects of depth and distance from shore on biodiversity, PLoS ONE, 11(1), p. e0146324. Thomson, PG, Fowler, AM, Davis, AR, Pattiaratchi, CB, & Booth, DJ (2018). Some Old Movies Become Classics – A Case Study Determining the Scientific Value of ROV Inspection Footage on a Platform on Australia’s North West Shelf, Frontiers in Marine Science, 5, pp. 1–18. 176 App 2: Summary of Expeditions APPENDIX 2: SUMMARY OF EXPEDITIONS Table A2.1 Summary of all expeditions in which seabed stereo-BRUVS were deployed. The table includes number of days over which the expedition occurred (Days), latitude (LAT) and longitude (LONG) of the locations in decimal degrees, and the number of seabed stereo-BRUVS deployed (n). Location Northeast Torres Strait - East Torres Strait - West Ribbons - Central Ribbons - North Ribbons - South East Cape York - Middle East Cape York - North East Cape York - South Cocos (Keeling Islands) Cocos Northwest Adele Island Ashmore Reef Barrow Island Dampier Archipelago Holothuria Reef Long Reef Rowley Shoals Wandoo Wandoo Platform Wandoo Reef Wandoo Sand Central North Ningaloo Reef - North Ningaloo Reef - Middle Ningaloo Reef - South Year Start Date End Date Days LAT LONG n 2017 2017 2017 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 19/06/2017 13/06/2017 4/04/2017 15/04/2018 16/06/2017 26/04/2018 29/04/2017 14/04/2018 7/06/2017 21/04/2018 9/06/2017 23/04/2018 6/04/2017 30/11/2017 15/06/2017 6/12/2017 3/05/2018 18/06/2017 28/04/2018 29/04/2017 14/04/2018 5/12/2017 27/04/2018 3/12/2017 25/04/2018 15/04/2017 5 3 16 20 3 3 1 1 4 7 6 3 10 -10.08 -9.93 -13.76 -13.69 -10.74 -12.24 -14.28 -14.40 -12.18 -12.25 -11.52 -11.54 -14.11 143.63 143.33 143.89 143.81 143.97 143.27 144.77 144.91 143.24 143.22 142.99 142.99 144.24 93 60 364 225 60 40 20 20 80 40 140 60 64 2016 10/11/2016 20/11/2016 11 -12.12 96.86 203 2017 2017 2018 2008 2009 2010 2008 2017 2017 2018 2017 23/07/2017 14/07/2017 2/10/2018 21/10/2008 17/03/2009 23/02/2010 1/08/2008 12/07/2017 30/06/2017 18/09/2018 19/11/2017 23/07/2017 21/07/2017 7/10/2018 27/10/2008 24/03/2009 1/03/2010 18/08/2008 12/07/2017 13/07/2017 23/09/2018 22/11/2017 1 8 8 7 8 7 18 1 14 6 4 -15.55 -12.24 -11.28 -20.83 -20.82 -20.79 -20.47 -13.57 -13.90 -13.97 -17.19 123.16 123.03 114.42 115.51 115.50 115.48 116.72 125.98 125.75 125.75 119.52 20 160 120 159 218 180 419 20 140 120 85 2017 2018 2019 2017 2018 2019 2018 2019 4/05/2017 19/04/2018 25/04/2019 6/05/2017 25/04/2018 9/09/2019 22/04/2018 30/04/2019 2/10/2017 7/09/2018 11/09/2019 4/10/2017 26/04/2018 11/09/2019 19/09/2018 30/04/2019 8 9 10 9 2 3 6 1 -20.13 -20.13 -20.13 -20.15 -20.15 -20.15 -20.07 -20.07 116.43 116.43 116.43 116.22 116.22 116.22 116.64 116.64 100 100 95 100 25 50 100 25 2006 2007 2009 2006 2009 2009 22/04/2006 8/02/2007 26/03/2009 7/05/2006 28/03/2009 1/04/2009 22/11/2006 11/12/2007 1/05/2009 16/05/2006 2/05/2009 10/04/2009 30 25 10 10 16 10 -22.14 -22.10 -22.19 -22.62 -22.73 -23.76 113.86 113.89 113.79 113.63 113.59 113.32 410 350 238 108 274 183 177 App 2: Summary of Expeditions Central South Shark Bay - Dirk Hartog Island Shark Bay - Gulf Shark Bay - South Passage Shark Bay - Steep Point 2017 2018 2009 16/09/2017 12/08/2018 16/09/2009 20/09/2017 12/08/2018 20/09/2009 5 1 5 -26.00 -26.01 -25.95 113.11 113.12 113.22 20 20 324 2018 2017 2018 4/08/2018 15/09/2017 8/08/2018 4/08/2018 16/09/2017 11/08/2018 1 2 3 -26.15 -26.22 -26.32 113.20 113.22 113.26 10 20 45 Table A2.2 Summary of all expeditions in which mid-water stereo-BRUVS were deployed. The table includes number of days over which the expedition occurred (Days), latitude (LAT) and longitude (LONG) of the locations in decimal degrees, and the number of mid-water stereo-BRUVS deployed (n). Location Northeast Great Barrier Reef North Cocos (Keeling) Islands Cocos Island Northwest Ashmore Reef - North Ashmore Reef - South Long Reef East Long Reef West Montebello Islands Montebello Islands Offshore Muiron Islands Rowley Shoals Rowley Shoals - Offshore Wandoo Wandoo Platform Wandoo Reef Wandoo Sand Central North Ningaloo Reef - Offshore Ningaloo Reef Year Start Date End Date Days LAT LONG n 2017 7/06/2017 6/12/2017 22 11.17 143.44 72 2016 11/10/2016 21/11/2016 11 12.13 96.829 94 2017 2018 2017 2018 2017 2018 2018 14/07/2017 2/10/2018 6/07/2017 18/09/2018 30/06/2017 18/09/2018 17/08/2018 21/07/2017 7/10/2018 13/07/2017 23/09/2018 12/07/2017 23/09/2018 23/08/2018 8 6 8 6 13 6 7 12.20 12.21 13.85 13.90 13.82 13.85 -20.28 123.05 123.05 125.89 125.92 125.68 125.55 115.36 75 75 14 55 48 59 98 2018 2018 2017 2017 2018 15/08/2018 25/07/2018 19/11/2017 16/11/2017 4/08/2018 22/08/2018 25/07/2018 22/11/2017 18/11/2017 10/08/2018 8 1 4 3 7 19.88 21.61 17.09 15.14 15.45 115.35 114.20 119.42 118.49 118.52 98 19 38 59 179 2017 2018 2019 2017 2018 2019 2018 2019 1/05/2017 19/04/2018 26/04/2019 7/05/2017 25/04/2018 9/09/2019 22/04/2018 30/04/2019 2/10/2017 7/09/2018 11/09/2019 4/10/2017 26/04/2018 11/09/2019 19/09/2018 30/04/2019 11 12 9 8 5 3 6 1 20.13 20.13 20.12 20.14 20.15 20.14 20.06 20.06 116.42 116.42 116.43 116.21 116.2 116.21 116.63 116.63 42 43 37 41 24 35 44 19 2016 2016 2018 17/09/2016 15/09/2016 24/07/2018 22/09/2016 22/09/2016 30/07/2018 6 8 7 21.79 21.93 21.89 113.45 113.77 113.80 43 25 79 178 App 2: Summary of Expeditions Central South Shark Bay -Dirk Hartog Island Shark Bay - Gulf Shark Bay - Steep Point 2017 2018 2012 2012 2017 2018 16/09/2017 6/08/2018 19/04/2012 18/04/2012 15/09/2017 6/08/2018 20/09/2017 11/08/2018 25/04/2012 19/04/2012 21/09/2017 11/08/2018 5 6 7 3 7 6 26.04 25.94 26.12 26.15 26.28 26.30 112.96 112.94 113.17 113.13 113.12 113.13 30 32 56 10 45 61 179 App 3: Identification of potential species pool APPENDIX 3: IDENTIFICATION OF POTENTIAL SPECIES POOL Table A3.1 Potential species pool of tropical Australian threatened elasmobranchs, derived from Fishbase and Atlas of Living Australia (Froese and Pauly, 2019; www.ala.org.au, 2020). The IUCN Red List classification (IUCN) of each species is included (IUCN, 2020). Taxa identifications are in bold. For each family, identifications to genus are listed with all possible species in that genus. Identifications to family are listed thereafter, followed by any possible species in that family not already listed. Taxa Carcharhinidae Carcharhinus sp. Carcharhinus albimarginatus Carcharhinus altimus Carcharhinus amblyrhynchoides Carcharhinus amblyrhynchos Carcharhinus amboinensis Carcharhinus brevipinna Carcharhinus cautus Carcharhinus falciformis Carcharhinus fitzroyensis Carcharhinus leucas Carcharhinus limbatus Carcharhinus longimanus Carcharhinus macloti Carcharhinus melanopterus Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sorrah Carcharhinus tilstoni Carcharhinidae sp. Galeocerdo cuvier Glyphis garricki Loxodon macrorhinus Negaprion acutidens Prionace glauca Rhizoprionodon acutus Rhizoprionodon taylori Triaenodon obesus Myliobatidae Mobula sp. Mobula alfredi Mobula birostris Mobula eregoodootenkee Mobula thurstoni Rhinidae Rhynchobatus sp. Rhynchobatus palpebratus Rhynchobatus australiae Rhynhcobatus laevis Common name IUCN silvertip shark bignose shark graceful shark blacktail reef shark pigeye shark spinner shark nervous shark silky shark creek whaler bull shark blacktip shark oceanic whitetip shark hardnose shark blacktip reef shark dusky shark sandbar shark spot-tail shark Australian blacktip shark Vulnerable Data Deficient Near Threatened Near Threatened Data Deficient Near Threatened Data Deficient Vulnerable Least Concern Near Threatened Near Threatened Critically Endangered Near Threatened Near Threatened Endangered Vulnerable Near Threatened Least Concern tiger shark northern river shark sliteye shark lemon shark blue shark milk shark Australian sharpnose shark white tip reef shark Near Threatened Critically Endangered Least Concern Vulnerable Near Threatened Least Concern Least Concern Near Threatened reef manta giant manta longhorned mobula bentfin devilray Vulnerable Vulnerable Endangered Endangered eyebrow wedgefish bottlenose wedgefish smoothnose wedgefish Near Threatened Critically Endangered Critically Endangered 180 Table A3.2 Potential species identifications for those taxa identified to family or genus, separated by family. Species records for the area surrounding Wandoo and the two control sites are derived from Fishbase, Sealifebase and Atlas of Living Australia (Froese and Pauly, 2019; Palomares and Pauly, 2019; www.ala.org.au, 2020). Taxa identifications are in bold. For each family, identifications to genus are listed with all possible species in that genus. Identifications to family are listed thereafter, followed by any possible species in that family not already listed. Common Name ringtail surgeonfish dark surgeonfish pencil surgeonfish inshore surgeonfish pale-lipped surgeonfish bluelined surgeonfish pale surgeonfish velvet surgeonfish eyeline surgeonfish dusky surgeonfish orangeblotch surgeonfish mimic surgeonfish convict surgeonfish yellowmask surgeonfish ringtail unicornfish spotted unicornfish silverblotched unicornfish horseface unicornfish sleek unicornfish clown unicornfish Binomial Naso lopezi Naso mcdadei Naso reticulatus Naso unicornis Naso vlamingii Apogonidae Apogonidae sp. Apogon crassiceps Apogon semiornatus Apogon unicolor Common Name slender unicornfish squarenose unicornfish reticulate unicornfish bluespine unicornfish bignose unicornfish ruby cardinalfish halfband cardinalfish big red cardinalfish App 3: Identification of potential species pool 181 Binomial Acanthuridae Acanthurus sp. Acanthurus auranticavus Acanthurus blochii Acanthurus dussumieri Acanthurus grammoptilus Acanthurus leucocheilus Acanthurus lineatus Acanthurus mata Acanthurus nigricans Acanthurus nigricauda Acanthurus nigrofuscus Acanthurus olivaceus Acanthurus pyroferus Acanthurus triostegus Acanthurus xanthopterus Naso sp. Naso annulatus Naso brevirostris Naso caesius Naso fageni Naso hexacanthus Naso lituratus Common Name bullseye cardinalfish manyband cardinalfish Timor cardinalfish cryptic cardinalfish tiger cardinalfish fiveline cardinalfish samoan cardinalfish crosseye cardinalfish variegated cardinalfish silvermouth siphonfish keeled cardinalfish monster cardinalfish flagfin cardinalfish circular cardinalfish ghost cardinalfish broadstripe cardinalfish blackbelly cardinalfish ringtail cardinalfish whiteline cardinalfish Cook's cardinalfish orangelined cardinalfish fourline cardinalfish striped cardinalfish moluccan cardinalfish nineline cardinalfish palestriped cardinalfish coral cardinalfish Binomial Ostorhinchus rueppellii Ostorhinchus semilineatus Ostorhinchus septemstriatus Ostorhinchus taeniophorus Ostorhinchus wassinki Ozichthys albimaculosus Paxton concilians Pristiapogon exostigma Pristiapogon fraenatus Pristiapogon unitaeniatus Pristicon rhodopterus Pristicon trimaculata Pseudamia gelatinosa Quinca mirifica Rhabdamia gracilis Common Name western gobbleguts blacktip cardinalfish sevenband cardinalfish pearly-line cardinalfish Kupang cardinalfish creamspotted cardinalfish Paxton's cardinalfish oneline cardinalfish spinyeye cardinalfish singlestripe cardinalfish twobar cardinalfish threespot cardinalfish gelatinous cardinalfish sailfin cardinalfish slender cardinalfish App 3: Identification of potential species pool 182 Binomial Apogonichthyoides atripes Apogonichthyoides brevicaudatus Apogonichthyoides timorensis Apogonichthyoides umbratilis Cheilodipterus macrodon Cheilodipterus quinquelineatus Foa fo Fowleria aurita Fowleria variegata Jaydia argyrogaster Jaydia carinata Jaydia melanopus Jaydia truncata Neamia articycla Nectamia fusca Ostorhinchus angustatus Ostorhinchus atrogaster Ostorhinchus aureus Ostorhinchus cavitensis Ostorhinchus cookii Ostorhinchus cyanosoma Ostorhinchus doederleini Ostorhinchus fasciatus Ostorhinchus monospilus Ostorhinchus novemfasciatus Ostorhinchus pallidofasciatus Ostorhinchus properuptus Common Name striped siphonfish pinkbreast siphonfish urchin cardinalfish painted cardinalfish blackspot cardinalfish cake star sand sea star comb sea star starfish cushion seastar pincushion starfish Luzon seastar red starfish - Binomial Gymnanthenea globigera Hacelia helicosticha Halityle regularis Heteronardoa carinata Indianastra sarasini Linckia guildingi Linckia laevigata Linckia multifora Luidia hardwicki Luidia maculata Metrodira subulata Nardoa galatheae Ogmaster capella Ophidiaster granifer Pentaceraster gracilis Common Name mosaic cushion star common comet star blue seastar spotted linckia luidia sand star galathea sea star grained seastar gracilis seastar App 3: Identification of potential species pool 183 Binomial Siphamia majimai Siphamia roseigaster Siphamia tubifer Taeniamia fucata Taeniamia melasma Asteroidea Asteroidea sp. Anthenea aspera Anthenea pentagonula Anthenea sibogae Anthenea viguieri Anthenoides dubius Archaster angulatus Asterodiscides soelae Astropecten granulatus Astropecten polyacanthus Astropecten zebra Coronaster halicepus Ctenodiscus orientalis Culcita novaeguineae Culcita schmideliana Echinaster luzonicus Echinaster varicolor Fromia indica Gomophia sphenisci Goniodiscaster acanthodes Goniodiscaster forficulatus Goniodiscaster rugosus Common Name knobbly seastar - yellowmargin triggerfish yellowspotted triggerfish hairfin triggerfish starry triggerfish orangestripe triggerfish redtooth triggerfish hawaiian triggerfish eye-stripe triggerfish bridled triggerfish lined triggerfish linespot fangblenny yellow fangblenny Binomial Plagiotremus rhinorhynchos Plagiotremus tapeinosoma Blenniidae sp. Aspidontus dussumieri Aspidontus taeniatus Atrosalarias fuscus Blenniella chrysospilos Blenniella periophthalmus Cirripectes alleni Cirripectes castaneus Cirripectes filamentosus Crossosalarias macrospilus Ecsenius alleni Ecsenius bicolor Ecsenius lineatus Common Name bluestriped fangblenny piano fangblenny lance blenny false cleanerfish dusky blenny redspotted rockskipper bluestreaked rockskipper kimberley blenny chestnut blenny filamentous blenny triplespot blenny Allen's combtooth blenny bicolor combtooth blenny lined combtooth blenny App 3: Identification of potential species pool 184 Binomial Pentaceraster regulus Protoreaster nodulosus Pseudoreaster obtusangulus Rosaster symbolicus Stellaster childreni Stellaster equestris Stellaster inspinosus Stellaster squamulosus Tamaria tumescens Thromidia brycei Balistidae Pseudobalistes sp. Pseudobalistes flavimarginatus Pseudobalistes fuscus Balistidae sp. Abalistes filamentosus Abalistes stellatus Balistapus undulatus Odonus niger Rhinecanthus aculeatus Sufflamen chrysopterus Sufflamen fraenatum Xanthichthys lineopunctatus Blenniidae Meiacanthus sp. Meiacanthus grammistes Meiacanthus luteus Plagiotremus sp. Common Name ocular combtooth blenny palespotted combtooth blenny wavyline rockskipper blackspotted rockskipper twinspot rockskipper delicate blenny rippled rockskipper lined rockskipper peacock rockskipper manyspot blenny mimic blenny Germain's blenny muzzled blenny rotund blenny vertical blenny shorthead sabretooth blenny crested sabretooth blenny banded blenny Spalding's blenny Talbot's blenny hairtail blenny oval flounder leopard flounder - Binomial Atergatopsis tweediei Banareia armata Bathypilumnus nigrispinifer Bathypilumnus pugilator Calappa capellonis Calappa clypeata Calappa philargius Calappa woodmasoni Charybdis (Charybdis) granulata Charybdis (Charybdis) jaubertensis Cryptodromiopsis unidentata Cycloachelous orbitosinus Demania splendida Dorippe quadridens Common Name red-spotted box crab little crested crab App 3: Identification of potential species pool 185 Binomial Ecsenius oculatus Ecsenius yaeyamaensis Entomacrodus decussatus Entomacrodus striatus Entomacrodus thalassinus Glyptoparus delicatulus Istiblennius edentulus Istiblennius lineatus Istiblennius meleagris Laiphognathus multimaculatus Mimoblennius atrocinctus Omobranchus germaini Omobranchus punctatus Omobranchus rotundiceps Omobranchus verticalis Petroscirtes breviceps Petroscirtes mitratus Salarias fasciatus Salarias sexfilum Stanulus talboti Xiphasia setifer Bothidae Bothus sp. Bothus myriaster Bothus pantherinus Brachyura Brachyura sp. Atergatopsis alcocki Common Name sponge crab thin-shelled spider crab sculptured porcelain crab - Binomial Petrolisthes scabriculus Pilumnus minutus Pilumnus scabriusculus Pilumnus semilanatus Platypodia semigranosa Polyonyx biunguiculatus Portunus armatus Portunus gladiator Portunus gracilimanus Portunus longispinosus Portunus rugosus Portunus tuberculosus Prismatopus longispinus Schizophrys dama Thalamita quadrilobata Common Name ragged crab blue swimmer crab pronghorn decorator crab App 3: Identification of potential species pool 186 Binomial Dromidiopsis edwardsi Eumedonus niger Gaillardiellus rueppelli Glabropilumnus seminudus Hepatoporus guinotae Hyastenus sebae Hyastenus spinosus Izanami curtispina Izanami inermis Laleonectes nipponensis Lissocarcinus laevis Lissoporcellana pectinata Lissoporcellana quadrilobata Lupocyclus rotundatus Lupocyclus tugelae Menaethius monoceros Myra eudactylus Myrine kessleri Naxioides taurus Neopalicus jukesii Neoxanthops lineatus Oncinopus aranea Pachycheles sculptus Palapedia quadriceps Palapedia roycei Paramaya spinigera Paranaxia serpulifera Petrolisthes militaris Common Name - yellowband fusilier doubleline fusilier neon fusilier goldband fusilier yellowtail fusilier blue fusilier mottled fusilier smallmouth scad razorbelly trevally herring scad longfin trevally longnose trevally onion trevally shadow trevally whitefin trevally blue trevally Binomial Carangoides fulvoguttatus Carangoides gymnostethus Carangoides hedlandensis Carangoides humerosus Carangoides malabaricus Carangoides oblongus Carangoides orthogrammus Caranx sp. Caranx bucculentus Caranx ignobilis Caranx melampygus Caranx papuensis Caranx sexfasciatus Caranx tille Decapterus sp. Common Name turrum bludger trevally bumpnose trevally epaulette trevally Malabar trevally coachwhip trevally thicklip trevally bluespotted trevally giant trevally bluefin trevally brassy trevally bigeye trevally tille trevally App 3: Identification of potential species pool 187 Binomial Thalamita sexlobata Thalamita spinifera Tokoyo eburnea Trigonoplax spathulifera Urnalana pulchella Zebrida adamsi Caesionidae Pterocaesio sp. Pterocaesio chrysozona Pterocaesio digramma Pterocaesio tile Caesionidae sp. Caesio caerulaurea Caesio cuning Caesio teres Dipterygonotus balteatus Carangidae Alepes sp. Alepes apercna Alepes kleinii Alepes vari Carangoides sp. Carangoides armatus Carangoides chrysophrys Carangoides coeruleopinnatus Carangoides dinema Carangoides equula Carangoides ferdau Common Name mackerel scad slender scad Indian scad rough-ear scad giant queenfish lesser queenfish needleskin queenfish oxeye scad bigeye scad amberjack samsonfish highfin amberjack barred yellowtail scad golden trevally finny scad pilotfish black pomfret silver trevally yellowstripe scad smallspotted dart snubnose dart common jack mackerel yellowtail scad silvermouth trevally Binomial Ulua mentalis Uraspis uraspis Carcharhinidae Carcharhinus sp. Carcharhinus altimus Carcharhinus amblyrhynchos Carcharhinus amboinensis Carcharhinus brevipinna Carcharhinus coatesi Carcharhinus falciformis Carcharhinus galapagensis Carcharhinus leucas Carcharhinus limbatus Carcharhinus longimanus Carcharhinus melanopterus Common Name longraker trevally whitemouth trevally bignose shark grey reef shark pigeye shark spinner shark whitecheek shark silky shark Galapagos shark bull shark common blacktip shark oceanic whitetip shark blacktip reef shark App 3: Identification of potential species pool 188 Binomial Decapterus macarellus Decapterus macrosoma Decapterus russelli Decapterus tabl Scomberoides sp. Scomberoides commersonnianus Scomberoides lysan Scomberoides tol Selar sp. Selar boops Selar crumenophthalmus Seriola sp. Seriola dumerili Seriola hippos Seriola rivoliana Carangidae sp. Atule mate Gnathanodon speciosus Megalaspis cordyla Naucrates ductor Parastromateus niger Pseudocaranx georgianus Selaroides leptolepis Trachinotus baillonii Trachinotus blochii Trachurus declivis Trachurus novaezelandiae Ulua aurochs Common Name dusky sharl sandbar shark spot-tail shark Australian blacktip shark tiger shark northern river shark sliteye shark lemon shark blue shark milk shark Australian sharpnose shark white tip reef shark highfin coralfish orangebanded coralfish longfin bannerfish pennant bannerfish schooling bannerfish masked bannerfish singular bannerfish Philippine butterflyfish western butterflyfish goldstripe butterflyfish threadfin butterflyfish Binomial Chaetodon bennetti Chaetodon citrinellus Chaetodon ephippium Chaetodon kleinii Chaetodon lineolatus Chaetodon lunula Chaetodon lunulatus Chaetodon melannotus Chaetodon ornatissimus Chaetodon plebeius Chaetodon speculum Chaetodon trifascialis Chaetodon ulietensis Chaetodon unimaculatus Chaetodon vagabundus Common Name eclipse butterflyfish citron butterflyfish saddle butterflyfish Klein’s butterflyfish lined butterflyfish racoon butterflyfish pinstripe butterflyfish blackback butterflyfish ornate butterflyfish bluespot butterflyfish ovalspot butterflyfish chevron butterflyfish doublesaddle butterflyfish teardrop butterflyfish vagabond butterflyfish App 3: Identification of potential species pool 189 Binomial Carcharhinus obscurus Carcharhinus plumbeus Carcharhinus sorrah Carcharhinus tilstoni Carcharhinidae sp. Galeocerdo cuvier Glyphis garricki Loxodon macrorhinus Negaprion acutidens Prionace glauca Rhizoprionodon acutus Rhizoprionodon taylori Triaenodon obesus Chaetodontidae Coradion sp. Coradion altivelis Coradion chrysozonus Heniochus sp. Heniochus acuminatus Heniochus chrysostomus Heniochus diphreutes Heniochus monoceros Heniochus singularius Chaetodontidae sp. Chaetodon adiergastos Chaetodon assarius Chaetodon aureofasciatus Chaetodon auriga Common Name margined coralfish Muller’s coralfish beaked coralfish forceps fish ocellate butterflyfish tripleband butterflyfish loggerhead turtle green turtle hawksbill turtle flatback turtle freckled hawkfish arc-eye hawkfish whitespot hawkfish blotched hawkfish dwarf hawkfish lyretail hawkfish white sardinella goldstripe sardinella bali sardinella blacktip sardinella Binomial Amblygaster sirm Dussumieria elopsoides Herklotsichthys koningsbergeri Herklotsichthys lippa Spratelloides delicatulus Spratelloides gracilis Spratelloides robustus Congridae Gorgasia sp. Gorgasia maculata Gorgasia preclara Crinoidea Crinoidea sp. Amphimetra tessellata Cenometra cornuta Common Name spotted sardine slender sardine largespotted herring smallspotted herring blueback sprat slender sprat blue sprat whitespotted garden eel splendid garden eel App 3: Identification of potential species pool 190 Binomial Chelmon marginalis Chelmon muelleri Chelmon rostratus Forcipiger flavissimus Parachaetodon ocellatus Roa australis Cheloniidae Cheloniidae sp. Caretta caretta Chelonia mydas Eretmochelys imbricata Natator depressus Cirrhitidae Paracirrhites sp. Paracirrhites forsteri Paracirrhites arcatus Paracirrhites hemistictus Cirrhitidae sp. Cirrhitichthys aprinus Cirrhitichthys falco Cyprinocirrhites polyactis Clupeidae Sardinella sp. Sardinella albella Sardinella gibbosa Sardinella lemuru Sardinella melanura Clupeidae sp. Common Name - plain maskray bluespotted maskray painted maskray smooth stingray dwarf black stingray reticulate whipray leopard whipray blackspotted whipray brown whipray cowtail stingray pink whipray Jenkins' whipray bluespotted fantail ray blotched fantail ray porcupine ray mangrove whipray Binomial Delphinidae sp. Sousa sahulensis Stenella longirostris Tursiops truncatus Echeneidae Remora sp. Remora remora Remora albescens Remora australis Remora osteochir Echeneidae sp. Echeneis naucrates Echinoidea Echinoidea sp. Astropyga radiata Common Name Australian humpbacked dolphin spinner dolphin bottlenose dolphin remora white suckerfish whalesucker marlin sucker sharksucker App 3: Identification of potential species pool 191 Binomial Colobometra perspinosa Comatella nigra Comatula rotalaria Dorometra parvicirra Heterometra crenulata Petasometra clarae Phanogenia distinctus Pterometra pulcherrima Dasyatidae Neotrygon sp. Neotrygon annotata Neotrygon australiae Neotrygon leylandi Dasyatidae sp. Bathytoshia brevicaudata Hemitrygon parvonigra Himantura australis Himantura leoparda Maculabatis astra Maculabatis toshi Pastinachus ater Pateobatis fai Pateobatis jenkinsii Taeniura lymma Taeniurops meyeni Urogymnus asperrimus Urogymnus granulatus Delphinidae Common Name heart urchin sea urchin needlespined sea urchin burrowing sea urchin heart urchin heart urchin - Binomial Salmaciella dussumieri Salmacis belli Schizaster (Schizaster) compactus Stylocidaris bracteata Temnopleurus alexandri Temnopleurus michaelseni Toxopneustes pileolus Tripneustes gratilla Elapidae Aipysurus sp. Aipysurus apraefrontalis Aipysurus duboisii Aipysurus laevis Aipysurus tenuis Hydrophis sp. Common Name sea urchin collector sea urchin short-nosed seasnake reef shallows seasnake golden seasnake brown-lined seasnake App 3: Identification of potential species pool 192 Binomial Breynia australasiae Breynia desorii Brissus latecarinatus Chaetodiadema granulatum Clypeaster telurus Clypeaster virescens Diadema savignyi Diadema setosum Echinocyamus crispus Echinocyamus planissimus Echinodiscus auritus Echinolampas ovata Echinometra mathaei Echinostrephus molaris Lovenia elongata Metabonellia haswelli Metalia angustus Metalia sternalis Nudechinus darnleyensis Nudechinus scotiopremnus Peronella lesueuri Peronella orbicularis Peronella tuberculata Phyllacanthus imperialis Phyllacanthus longispinus Prionocidaris baculosa Prionocidaris bispinosa Rhynobrissus hemiasteroides Common Name fine-spined seasnake elegant seasnake olive-headed seasnake spotted seasnake ornate reef sea snake Stokes's seasnake north-western shovel-nosed snake rufous whipsnake turtle-headed seasnake north-western mangrove seasnake orange-naped snake monk snake king brown snake western brown snake little spotted snake humphead batfish round batfish longfin batfish shortfin batfish smooth flutemouth rough flutemouth Binomial Gastropoda sp. Adamnestia arachis Akera soluta Allochroa layardi Amalda lineata Amoria dampieria Amoria grayi Amoria macandrewi Amoria praetexta Ancillista muscae Angaria delphinus Aplysia dactylomela Aplysia parvula Archimediella dirkhartogensis Archimediella fastigiata Common Name Gray's volute Macandrew's volute juvenile volute elongate ancilla imperial delphinula App 3: Identification of potential species pool 193 Binomial Hydrophis czeblukovi Hydrophis elegans Hydrophis major Hydrophis ocellatus Hydrophis ornatus Hydrophis stokesii Elapidae sp. Brachyurophis approximans Demansia rufescens Emydocephalus annulatus Ephalophis greyi Furina ornata Parasuta monachus Pseudechis australis Pseudonaja mengdeni Suta punctata Ephippidae Platax sp. Platax batavianus Platax orbicularis Platax pinnatus Ephippidae sp. Zabidius novemaculeatus Fistulariidae Fistularia sp. Fistularia commersonii Fistularia petimba Gastropoda Common Name spurred turban shell frilled star scaly star shell blue mouthed turban dory austrocochlea swallow cowry frog shell granulated bursa Waterhouse's triton flower stromb - Binomial Cellana radiata Cellana turbator Cerithium atromarginatum Cerithium balteatum Cerithium novaehollandiae Cerithium torresi Cerithium traillii Cerithium zonatum Cheilea equestris Chelidonura amoena Chelidonura hirundinina Chicoreus (Chicoreus) cornucervi Chicoreus (Triplex) cervicornis Chicoreus (Triplex) microphyllus Chicoreus (Triplex) strigatus Common Name radiate patellid limpet creeper cup & saucer limpet single tooth murex murex shell short-fronded murex Penchinatt's murex App 3: Identification of potential species pool 194 Binomial Aspella platylaevis Astralium calcar Astralium pileolum Astralium squamiferum Astralium stellare Atys cylindricus Atys naucum Atys semistriatus Austrocochlea zeus Berthella martensi Berthellina citrina Bistolida hirundo Blasicrura pallidula Bostrycapulus pritzkeri Bufonaria rana Bulla ampulla Bulla vernicosa Bullina lineata Bursa granularis Cabestana tabulata Calthalotia mundula Canarium mutabile Cantharidus crenelliferus Cantharidus gilberti Cantharidus polychroma Cantharus erythrostomus Cassidula (Cassidula) aurisfelis Cavolinia uncinata Common Name the scorched murex varicose ladder shell fleshy peristernia creeper double-banded creeper nodoluse cominella d'Orbigny's cone conical sand snail the cloth-of-gold cone Queen Victoria'sp. cone geographer cone acorn cone choice cone triangular cone pricked cone flag cone - Binomial Coralliophila confusa Coralliophila costularis Crepidula aculeata Cribrarula cribraria Cronia (Cronia) avellana Cupidoliva nympha Cyerce nigricans Cyllene sulcata Cymbiola nivosa Dermomurex (Viator) antonius Diacavolinia longirostris Diala albugo Diala lirulata Diodora jukesii Diodora singaporensis Common Name small-ribbed purpura slipper limpet filbert-nut buccinum nymph rice shell blotched snowflake volute keyhole limpet - 195 App 3: Identification of potential species pool Binomial Chicoreus (Triplex) torrefactus Cinguloterebra marrowae Cirsotrema varicosa Clanculus atropurpureus Clanculus comarilis Clanculus margaritarius Clivipollia incarnata Clypeomorus batillariaeformis Clypeomorus bifasciata Colina macrostoma Colsyrnola sericea Cominella (Cominella) acutinodosa Conasprella (Fusiconus) orbignyi Conuber conicus Conus (Cylinder) textile Conus (Cylinder) victoriae Conus (Gastridium) geographus Conus (Leporiconus) glans Conus (Lividoconus) eximius Conus (Lividoconus) lischkeanus Conus (Phasmoconus) dampierensis Conus (Plicaustraconus) trigonus Conus (Rhizoconus) pertusus Conus (Rhizoconus) vexillum Conus (Tesselliconus) suturatus Conus monachus Common Name reticulate triton Campbell's stromb riband marked stromb oyster drill hime-shiro-reishi-damashi duplicate auger contracted buccinum cylindrical cowry erroneus cowry depressed top shell the black beaded top shell red bead shell - Binomial Fusiaphera macrospira Fusinus (Fusinus) colus Fusinus (Fusinus) undatus Fusolatirus paetelianus Gastrocopta hedleyi Gastrocopta mussoni Gemmula (Gemmula) dampierana Gemmula (Gemmula) diomedea Gibberula striata Granata maculata Gyrineum lacunatum Haliotis clathrata Haliotis diversicolor Haliotis varia Common Name distaff spindle brigalow pupasnail Musson's pupasnail variable abalone App 3: Identification of potential species pool 196 Binomial Distorsio reticularis Dolomena plicata Doxander campbelli Doxander vittatus Drupella margariticola Drupella rugosa Duplicaria duplicata Echinolittorina (Granulittorina) vidua Eclogavena quadrimaculata Elysia ornata Elysiella pusilla Emarginula (Emarginula) incisura Eoacmaea calamus Eratoena corrugata Eratoena gemma Ergalatax contracta Erronea caurica Erronea cylindrica Erronea errones Ethminolia vitiliginea Euchelus atratus Euchelus dampierensis Euchelus rubrus Euplica bidentata Euplica varians Euselenops luniceps Ficus eospila Binomial Lyncina carneola Macroschisma madreporaria Macroschisma munita Macroschisma producta Maculotriton serriale Malea pomum Mammilla simiae Mancinella alouina Mancinella echinata Marmorofusus nicobaricus Melampus (Melampus) flexuosus Melanella montagueana Melo amphora Melo umbilicatus Merica melanostoma Common Name purple mouthed cowry ridge-backed keyhole limpet elongated keyhole limpet granulated castor bean apple tun monkey sand shell pimpled purpura whelk melon shell bailer shell App 3: Identification of potential species pool 197 Binomial Common Name Haloa cymbalum Harpa articularis articulate harp shell Haustator (Kurosioia) cingulifera Heliacus (Heliacus) variegatus variegated sundial Herpetopoma instrictum Herpetopoma scabriuscula scurfy bead shell Hiatavolva depressa depressed little egg cowry Homalocantha secunda next-allied murex Hybochelus cancellatus Hydatina amplustre Hydatina physis Indomodulus tectum Inquisitor dampierius Inquisitor intertincta Inquisitor odhneri iravadia (pseudonoba) densilabrum Iravadia pilbara Ittibittium parcum Labiostrombus epidromis sail stromb Laetifautor monilis Latirus walkeri Liotina crassibassis Liotina peronii large liotia Littoraria cingulata periwinkle Littoraria scabra scabra periwinkle Lophiotoma acuta Lunella (Lunella) cinereus polished turban Luria isabella fawn-coloured cowry Common Name money cowrie shrewd trochid lipped periwinkle ploughed triton northern hairy triton rough notch limpet murex shell honey cowry acorn dog whelk whitish dog whelk egg yolk sand snail chamaeleon nerite wavy nerite plicate nerite tubercular nerite Binomial Neverita powisianus Nevia spirata Notarchus indicus Notocochlis gualtieriana Oliva brettinghami Onustus indicus Palmadusta clandestina Patelloida mimula Patelloida saccharina Peristernia reincarnata Phasianella solida Phasianella variegata Philine cf. aperta Phos (Phos) senticosus Pinaxia versicolor Common Name chestnut-banded sand snail spirate cross-barred shell northern star limpet variegated pheasant Pacific phos varicoloured thaid App 3: Identification of potential species pool 198 Binomial Mesoginella brachia Micromelo undata Monetaria caputserpentis Monetaria moneta Monilea callifera Monodonta labio Monoplex exaratus Monoplex pilearis Monoplex thersites Montfortista excentrica Montfortula pulchra Montfortula rugosa Morula (Habromorula) spinosa Murex (Murex) acanthostephes Murex (Murex) pecten Naria erosa Naria helvola Nassarius (Alectrion) glans Nassarius (Niotha) albescens Nassarius (Niotha) albinus Nassarius (Zeuxis) clarus Nassarius horridus Natica schepmani Natica vitellus Nerita (Argonerita) chamaeleon Nerita (Cymostyla) undata Nerita (Ritena) plicata Nerita (Theliostyla) albicilla Common Name flame pisania ribbed clusterwink waved buccinum Baudin's top shell Cuming's creeper murex shell Abrolhos sinistral pupasnail yellow dove - Binomial Quistrachia montebelloensis Ranularia cynocephalum Rapa rapa Reticunassa paupera Rhagada angulata Rhagada convicta Rhagada elachystoma Rhinoclavis (Proclava) kochi Rhinoclavis (Rhinoclavis) articulata Rhinoclavis (Rhinoclavis) brettinghami Rhinoclavis (Rhinoclavis) fasciata Rhinoclavis (Rhinoclavis) vertagus Rissoina (Phosinella) media Common Name dog's-head triton soft coral shell poor dog whelk creeper beautiful creeper banded creeper ribbed cerith App 3: Identification of potential species pool 199 Binomial Pirenella austrocingulata Pirenella rugosa Pisania (Pisania) ignea Planaxis sulcatus Pleurobranchaea maculata Pleurobranchus grandis Pleurobranchus peronii Pollia undosa Profundiconus teramachii Prothalotia baudini Prothalotia strigata Pseudostomatella papyracea Pseudovertagus (Pseudovertagus) aluco Pterochelus acanthopterus Pterochelus akation Ptychobela nodulosa Pupa solidula Pupoides contrarius Purpuradusta fimbriata Purpuradusta gracilis Purpuradusta hammondae Pyramidella acus Pyramidella dolabrata Pyramidella sulcatus Pyrene flava Pyrene punctata Quistrachia legendrei Common Name northern duck's bill air-breathing limpet beautiful neritina false ear shell keeled wide-mouthed shell banded black mitre painted sand snail latticed top shell pyramid trochus ponderous worm shell Binomial Tenguella granulata Terebellum terebellum Terebra amanda Terebralia semistriata Thalessa virgata Thuridilla indopacifica Tonna canaliculata Tonna perdix Tonna variegata Tricolia variabilis Tripterotyphis lowei Trivirostra edgari Trochus hanleyanus Trochus histrio tubulophilinopsis gardineri Common Name granulated drupe bullet stromb striate mud creeper prickly thaid partridge tun variegated tun minute pheasant Hanley's trochus - 200 App 3: Identification of potential species pool Binomial Rissoina (Rissoina) ambigua Rissoina (Rissoina) crassa Rissosyrnola aclis Sagaminopteron ornatum Sagaminopteron psychedelicum Scabricola (Scabricola) barrywilsoni Scalptia textilis Scutellastra flexuosa Scutus (Scutus) unguis Sericominolia vernicosa Siphonaria kurracheensis Siphonaria zelandica Smaragdia (Smaragdella) souverbiana Smaragdinella calyculata Staphylaea limacina Stomatella impertusa Stomatia phymotis Stomatia rubra Strigatella scutulata Surrepifungium costulata Talopena vernicosa Tanea euzona Tectonatica robillardi Tectus (Tectus) fenestratus Tectus (Tectus) pyramis Tenagodus ponderosus Common Name unarmed whelk Hayne's turban scaly turban little burnt turbo squamose turban cat's eye turban - diagonal shrimpgoby mask shrimpgoby broadbanded shrimpgoby burgundy shrimpgoby twospot eviota distigma eviota Binomial Eviota guttata Eviota inutilis Eviota melasma Eviota nebulosa Eviota prasina Eviota prasites Eviota queenslandica Eviota sebreei Eviota sigillata Eviota storthynx Eviota zebrina Valenciennea sp. Valenciennea alleni Valenciennea helsdingenii Valenciennea longipinnis Common Name whitelined eviota chestspot eviota headspot eviota palespot eviota rubble eviota hairfin eviota Queensland eviota striped eviota sign eviota rosy eviota zebra eviota Allen's glidergoby blacklined glidergoby ocellate glidergoby 201 App 3: Identification of potential species pool Binomial Tudivasum inerme Turbo (Carswellena) haynesi Turbo (Marmarostoma) argyrostomus Turbo (Marmarostoma) bruneus Turbo (Marmarostoma) squamosus Turbo (Turbo) petholatus Turcica maculata Turricula nelliae Turris crispa Vanitrochus tragema Variegemarginula variegata Vokesimurex multiplicatus Volutoconus hargreavesi Xenophora (Xenophora) cerea Xenophora (Xenophora) solarioides Xenuroturris millepunctata Gobiidae Amblyeleotris sp. Amblyeleotris diagonalis Amblyeleotris gymnocephalus Amblyeleotris periophthalmus Amblyeleotris wheeleri Eviota sp. Eviota bimaculata Eviota distigma Common Name mural glidergoby orangespotted glidergoby broadbarred glidergoby bynoe goby crosshatch goby pyjama goby whitebarred goby bluespotted mangrovegoby starry goby cryptic bearded goby cocos frillgoby dusky frillgoby Ladd's frillgoby large whipgoby loki whipgoby seawhip goby ostrich goby tripleband goby bluespotted shrimpgoby yellow shrimpgoby y-bar shrimpgoby goldspeckled shrimpgoby blackthroat goby twospot sandgoby neophyte sandgoby flasher sandgoby peacock sandgoby Binomial Gnatholepis cauerensis Gobiodon axillaris Gobiodon citrinus Gobiodon erythrospilus Gobiodon histrio Gobiodon quinquestrigatus Gobiodon rivulatus Gobiopsis angustifrons Hazeus diacanthus Hazeus elati Istigobius decoratus Istigobius goldmanni Istigobius nigroocellatus Istigobius ornatus Istigobius rigilius Common Name eye-bar sand-goby red-striped coralgoby lemon coralgoby blue-spotted coral-goby Māori coralgoby fiveline coralgoby rippled coralgoby narrow barbelgoby twospine sandgoby eilat sandgoby decorated sandgoby Goldmann's sandgoby blackspotted sandgoby ornate sandgoby orangespotted sandgoby App 3: Identification of potential species pool 202 Binomial Valenciennea muralis Valenciennea puellaris Valenciennea wardii Gobiidae sp. Amblygobius bynoensis Amblygobius decussatus Amblygobius nocturnus Amblygobius phalaena Amoya gracilis Asterropteryx semipunctata Barbuligobius boehlkei Bathygobius cocosensis Bathygobius fuscus Bathygobius laddi Bryaninops amplus Bryaninops loki Bryaninops yongei Callogobius maculipinnis Callogobius sclateri Cryptocentrus caeruleomaculatus Cryptocentrus cinctus Cryptocentrus fasciatus Ctenogobiops pomastictus Favonigobius melanobranchus Fusigobius duospilus Fusigobius neophytus Fusigobius signipinnis Gnatholepis argus Common Name dwarf slippery goby giant lobegoby ornate slippery goby Wilbur's goby Lidwill's dwarfgoby redhead stylophora goby blackfin coralgoby black coralgoby emerald coralgoby silverlined mudskipper solenocaulon ghostgoby softcoral ghostgoby slender spongegoby many-host ghostgoby lobed ghostgoby girdled reefgoby threadfin reefgoby orange convict reefgoby halfbarred reefgoby blacknose sueviota Larson's sueviota Glover's tasmangoby Nomura's dwarfgoby orange-red pygmygoby painted sweetlips blue bastard Binomial Plectorhinchus chaetodonoides Plectorhinchus flavomaculatus Plectorhinchus gibbosus Plectorhinchus lineatus Plectorhinchus multivittatus Plectorhinchus pica Plectorhinchus polytaenia Plectorhinchus unicolor Plectorhinchus vittatus Pomadasys argenteus Pomadasys kaakan Pomadasys maculatus Hemigaleidae Hemigaleidae sp. Hemigaleus australiensis Common Name spotted sweetlips goldspotted sweetlips brown sweetlips oblique-banded sweetlips manyline sweetlips dotted sweetlips ribbon sweetlips sombre sweetlips oriental sweetlips silver javelin barred javelin blotched javelin weasel shark App 3: Identification of potential species pool 203 Binomial Larsonella pumilus Lobulogobius omanensis Lubricogobius ornatus Macrodontogobius wilburi Pandaka lidwilli Paragobiodon echinocephalus Paragobiodon lacunicola Paragobiodon melanosoma Paragobiodon xanthosoma Periophthalmus argentilineatus Pleurosicya annandalei Pleurosicya boldinghi Pleurosicya elongata Pleurosicya mossambica Pleurosicya plicata Priolepis cincta Priolepis nuchifasciata Priolepis profunda Priolepis semidoliata Sueviota atrinasa Sueviota larsonae Tasmanogobius gloveri Trimma nomurai Trimma okinawae Haemulidae Haemulidae sp. Diagramma labiosum Plectorhinchus caeruleonothus Common Name fossil shark black marlin sailfish striped marlin blue marlin shortbill spearfish coral pigfish saddleback pigfish eclipse pigfish goldspot pigfish sunburnt pigfish blueside wrasse peacock wrasse redblotched wrasse spot-tail wrasse pinklined wrasse pixy wrasse bluethroat rainbow wrasse Australian rainbow wrasse soela wrasse Binomial Achoerodus gouldii Anampses caeruleopunctatus Anampses geographicus Anampses lennardi Anampses melanurus Calotomus carolinus Calotomus spinidens Cheilinus chlorourus Cheilinus trilobatus Cheilio inermis Choerodon anchorago Choerodon cauteroma Choerodon cephalotes Choerodon cyanodus Choerodon jordani Common Name western blue groper diamond wrasse scribbled wrasse blue-and-yellow wrasse blacktail wrasse star-eye parrotfish spinytooth parrotfish floral Māori wrasse tripletail Māori wrasse sharpnose wrasse anchor tuskfish bluespotted tuskfish purple tuskfish blue tuskfish dagger tuskfish App 3: Identification of potential species pool 204 Binomial Hemipristis elongata Istiophoridae Istiophoridae sp. Istiompax indica Istiophorus platypterus Kajikia audax Makaira nigricans Tetrapturus angustirostris Labridae Bodianus sp. Bodianus axillaris Bodianus bilunulatus Bodianus mesothorax Bodianus perditio Bodianus solatus Cirrhilabrus sp. Cirrhilabrus cyanopleura Cirrhilabrus temminckii Corissp. Coris aygula Coris caudimacula Coris dorsomacula Coris pictoides Suezichthys sp. Suezichthys cyanolaemus Suezichthys devisi Suezichthys soelae Labridae sp. Common Name darkspot tuskfish blackspot tuskfish wedgetail tuskfish redstripe tuskfish eyebrow tuskfish slingjaw wrasse Indian bird wrasse birdnose wrasse false-eyed wrasse pastel-green wrasse orangeline wrasse pearly wrasse dusky wrasse orangefin wrasse Hoeven's wrasse cloud wrasse bubblefin wrasse threespot wrasse fiveband wrasse thicklip wrasse ringed slender wrasse pastel slender wrasse red slender wrasse leaf wrasse keelhead razorfish blue razorfish oneline wrasse bicolor cleanerfish Binomial Labroides dimidiatus Leptojulis cyanopleura Leptoscarus vaigiensis Macropharyngodon meleagris Macropharyngodon negrosensis Macropharyngodon ornatus Oxycheilinus bimaculatus Oxycheilinus digramma Oxycheilinus orientalis Pseudocheilinus evanidus Pseudodax moluccanus Pteragogus cryptus Pteragogus enneacanthus Pteragogus flagellifer Stethojulis bandanensis Common Name common cleanerfish shoulderspot wrasse marbled parrotfish leopard wrasse black leopard wrasse ornate leopard wrasse little Māori wrasse violetline Māori wrasse oriental Māori wrasse pinstripe wrasse chiseltooth wrasse cryptic wrasse cockerel wrasse cocktail wrasse redspot wrasse App 3: Identification of potential species pool 205 Binomial Choerodon monostigma Choerodon schoenleinii Choerodon sugillatum Choerodon vitta Choerodon zamboangae Epibulus insidiator Gomphosus caeruleus Gomphosus varius Halichoeres biocellatus Halichoeres chloropterus Halichoeres hartzfeldii Halichoeres margaritaceus Halichoeres marginatus Halichoeres melanochir Halichoeres melanurus Halichoeres nebulosus Halichoeres nigrescens Halichoeres trimaculatus Hemigymnus fasciatus Hemigymnus melapterus Hologymnosus annulatus Hologymnosus doliatus Hologymnosus rhodonotus Iniistius dea Iniistius jacksonensis Iniistius pavo Labrichthys unilineatus Labroides bicolor Common Name brokenline wrasse silverstreak wrasse three-ribbon wrasse bluehead wrasse sixbar wrasse moon wrasse green moon wrasse surge wrasse pinkspeckled wrasse swallowtail seabream paddletail seabream Robinson's seabream grey seabream bluespotted seabream Ambon emperor yellowtail emperor orangespotted emperor longfin emperor threadfin emperor thumbprint emperor grass emperor redspot emperor smalltooth emperor redthroat emperor spangled emperor Binomial Lethrinus olivaceus Lethrinus ornatus Lethrinus punctulatus Lethrinus ravus Lethrinus rubrioperculatus Lethrinus semicinctus Lethrinus variegatus Lethrinidae sp. Gnathodentex aureolineatus Monotaxis grandoculis Lutjanidae Lutjanus sp. Lutjanus adetii Lutjanus argentimaculatus Lutjanus bitaeniatus Common Name longnose emperor ornate emperor bluespotted emperor drab emperor spotcheek emperor blackblotch emperor variegated emperor goldspot seabream bigeye seabream hussar mangrove jack Indonesian snapper App 3: Identification of potential species pool 206 Binomial Stethojulis interrupta Stethojulis strigiventer Stethojulis trilineata Thalassoma amblycephalus Thalassoma hardwicke Thalassoma lunare Thalassoma lutescens Thalassoma purpureum Xenojulis margaritacea Lethrinidae Gymnocranius sp. Gymnocranius elongatus Gymnocranius euanus Gymnocranius grandoculis Gymnocranius griseus Gymnocranius microdon Lethrinus sp. Lethrinus amboinensis Lethrinus atkinsoni Lethrinus erythracanthus Lethrinus erythropterus Lethrinus genivittatus Lethrinus harak Lethrinus laticaudis Lethrinus lentjan Lethrinus microdon Lethrinus miniatus Lethrinus nebulosus Common Name red bass stripey snapper checkered snapper crimson snapper blackspot snapper blacktail snapper golden snapper bluestriped snapper darktail snapper bigeye snapper saddletail snapper onespot snapper fiveline snapper Moses' snapper red emperor brownstripe snapper arrow dartgoby thread-tail dartgoby greeneye dartgoby lyretail dartgoby curious wormfish yellowstriped dartfish unicorn leatherjacket Binomial Aluterus scriptus Monacanthidae sp. Anacanthus barbatus Brachaluteres taylori Cantherhines dumerilii Cantherhines fronticinctus Cantherhines pardalis Chaetodermis penicilligerus Colurodontis paxmani Eubalichthys caeruleoguttatus Eubalichthys mosaicus Monacanthus chinensis Oxymonacanthus longirostris Paraluteres prionurus Common Name scrawled leatherjacket bearded leatherjacket Taylor's pygmy leatherjacket barred leatherjacket spectacled leatherjacket honeycomb leatherjacket tasselled leatherjacket Paxman's leatherjacket bluespotted leatherjacket mosaic leatherjacket fanbelly leatherjacket harlequin filefish blacksaddle filefish App 3: Identification of potential species pool 207 Binomial Lutjanus bohar Lutjanus carponotatus Lutjanus decussatus Lutjanus erythropterus Lutjanus fulviflamma Lutjanus fulvus Lutjanus johnii Lutjanus kasmira Lutjanus lemniscatus Lutjanus lutjanus Lutjanus malabaricus Lutjanus monostigma Lutjanus quinquelineatus Lutjanus russellii Lutjanus sebae Lutjanus vitta Microdesmidae Ptereleotris sp. Ptereleotris evides Ptereleotris hanae Ptereleotris microlepis Ptereleotris monoptera Microdesmidae sp. Gunnellichthys curiosus Parioglossus formosus Monacanthidae Aluterus sp. Aluterus monoceros Common Name pigface leatherjacket threadfin leatherjacket Japanese leatherjacket Sinhalese leatherjacket gillblotch leatherjacket fourband leatherjacket yellowspotted leatherjacket bicolour goatfish rosy goatfish diamondscale goatfish goldsaddle goatfish opalescent goatfish yellowspot goatfish banded goatfish sidespot goatfish blacksaddle goatfish yellowstripe goatfish latticetail moray headspot moray sieve moray stout moray fimbriate moray Binomial Gymnothorax flavimarginatus Gymnothorax javanicus Gymnothorax longinquus Gymnothorax mccoskeri Gymnothorax melatremus Gymnothorax minor Gymnothorax mucifer Gymnothorax prasinus Gymnothorax pseudothyrsoideus Gymnothorax thyrsoideus Gymnothorax undulatus Muraenidae sp. Echidna nebulosa Uropterygius marmoratus Myliobatidae Common Name yellowmargin moray giant moray long moray manyband moray dwarf moray lesser moray kidako moray green moray highfin moray greyface moray undulate moray starry moray marbled snake moray App 3: Identification of potential species pool 208 Binomial Paramonacanthus choirocephalus Paramonacanthus filicauda Paramonacanthus oblongus Paramonacanthus pusillus Pervagor janthinosoma Pseudomonacanthus elongatus Thamnaconus hypargyreus Mullidae Parupeneus sp. Parupeneus barberinoides Parupeneus chrysopleuron Parupeneus ciliatus Parupeneus cyclostomus Parupeneus heptacantha Parupeneus indicus Parupeneus multifasciatus Parupeneus pleurostigma Parupeneus spilurus Mullidae sp. Mulloidichthys flavolineatus Muraenidae Gymnothorax sp. Gymnothorax buroensis Gymnothorax cephalospilus Gymnothorax cribroris Gymnothorax eurostus Gymnothorax fimbriatus Common Name whitespotted eagle ray reef manta giant manta shortfin devilray bentfin devilray yellowbelly threadfin bream celebes threadfin bream rosy threadfin bream yellowtip threadfin bream notched threadfin bream fiveline threadfin bream golden threadfin bream slender threadfin bream purple threadfin bream Japanese threadfin bream paradise threadfin bream northwest threadfin bream western butterfish bridled monocle bream two-line monocle bream lined monocle bream redspot monocle bream rainbow monocle bream Binomial Scolopsis taenioptera Scolopsis taeniopterus Scolopsis xenochrous Nemipteridae sp. Parascolopsis inermis Parascolopsis rufomaculata Parascolopsis tanyactis Scaevius milii Nomeidae Psenes sp. Psenes arafurensis Psenes cyanophrys Psenes pellucidus Nomeidae sp. Cubiceps baxteri Common Name lattice monocle bream redspot monocle bream oblique-bar monocle bream redbelt monocle bream yellowband monocle bream longray monocle bream coral monocle bream banded driftfish freckled driftfish bluefin driftfish black fathead App 3: Identification of potential species pool 209 Binomial Mobula sp. Aetobatus ocellatus Mobula alfredi Mobula birostris Mobula kuhlii Mobula thurstoni Nemipteridae Nemipterus sp. Nemipterus bathybius Nemipterus celebicus Nemipterus furcosus Nemipterus nematopus Nemipterus peronii Nemipterus tambuloides Nemipterus virgatus Nemipterus zysron Pentapodus sp. Pentapodus emeryii Pentapodus nagasakiensis Pentapodus paradiseus Pentapodus porosus Pentapodus vitta Scolopsis sp. Scolopsis affinis Scolopsis bilineata Scolopsis lineata Scolopsis meridiana Scolopsis monogramma Common Name cape fathead Kotlyar's cubehead bigeye cigarfish shadow driftfish man-of-war fish day octopus frilled pygmy octopus banded stringarm octopus plain-spot octopus veined octopus red-spot night octopus greater blue-ringed octopus southern blue-ringed octopus blackstriped snake eel marbled snake eel saddled snake eel blackfin snake eel olive snake eel serpent eel flappy snake eel burrowing snake eel slender worm eel narrow worm eel Binomial Ophiuroidea Ophiuroidea sp. Amphioplus (Lymanella) depressus Amphipholis squamata Amphiura (Amphiura) bidentata Amphiura (Amphiura) duncani Amphiura (Amphiura) leucaspis Amphiura (Amphiura) maxima Amphiura (Amphiura) microsoma Amphiura (Amphiura) velox Amphiura (Fellaria) octacantha Dictenophiura stellata Macrophiothrix belli Macrophiothrix caenosa Common Name brooding brittle star App 3: Identification of potential species pool 210 Binomial Cubiceps capensis Cubiceps kotlyari Cubiceps pauciradiatus Cubiceps whiteleggii Nomeus gronovii Octopoda Octopus sp. Octopus cyanea Octopus superciliosus Octopoda sp. Ameloctopus litoralis Amphioctopus exannulatus Amphioctopus marginatus Callistoctopus dierythraeus Hapalochlaena lunulata Hapalochlaena maculosa Ophichtidae Ophichthidae sp. Callechelys catostoma Callechelys marmorata Leiuranus semicinctus Ophichthus altipennis Ophichthus rutidoderma Ophisurus serpens Phyllophichthus xenodontus Pisodonophis cancrivorus Scolecenchelys gymnota Scolecenchelys macroptera Common Name - Binomial Ophiomastix mixta Ophiomastix variabilis Ophiomaza cacaotica Ophionereis dubia Ophionereis semoni Ophioplocus imbricatus Ophiopsammus yoldii Ophiopteron elegans Ophiothela danae Ophiothrix (Keystonea) martensi Ophiothrix (Keystonea) smaragdina Ophiothrix (Ophiothrix) ciliaris Ophiothrix (Ophiothrix) exigua Ophiothrix (Ophiothrix) foveolata Common Name App 3: Identification of potential species pool 211 Binomial Macrophiothrix callizona Macrophiothrix koehleri Macrophiothrix lineocaerulea Macrophiothrix longipeda Macrophiothrix megapoma Macrophiothrix paucispina Macrophiothrix variabilis Ophiacantha indica Ophiactis brevis Ophiactis fuscolineata Ophiactis luteomaculata Ophiactis macrolepidota Ophiactis modesta Ophiactis savignyi Ophiarachnella gorgonia Ophiarachnella infernalis Ophiocentrus dilatatus Ophiochaeta hirsuta Ophiochasma stellata Ophiocnemis marmorata Ophiocoma dentata Ophiocomella sexradia Ophioconis cincta Ophiodaphne formata Ophiodyscrita acosmeta Ophiogymna pulchella Ophiolepis cincta Ophiolepis unicolor Common Name - longhorn cowfish roundbelly cowfish thornback cowfish yellow boxfish black boxfish shortnose boxfish horn-nose boxfish shortnose boxfish humpback turretfish smallspine turretfish - ornate spiny lobster painted spiny lobster bluenose grubfish Binomial Parapercis clathrata Parapercis haackei Parapercis multiplicata Parapercis nebulosa Parapercis rubricaudalis Parapercis rubromaculata Parapercis snyderi Parapercis xanthozona Pinguipedidae sp. Ryukyupercis gushikeni Polycheata Polycheata sp. Ceratonereis australis Ceratonereis mirabilis Ceratonereis singularis Common Name spothead grubfish wavy grubfish doublestitch grubfish pinkbanded grubfish redtail sandperch redspot sandperch Snyder's grubfish peppered grubfish rosy grubfish App 3: Identification of potential species pool 212 Binomial Ophiothrix (Ophiothrix) plana Ophiothrix (Placophiothrix) lineocaerulea Ophiothrix (Placophiothrix) melanosticta Ostraciidae Ostraciidae sp. Lactoria cornuta Lactoria diaphana Lactoria fornasini Ostracion cubicus Ostracion meleagris Ostracion nasus Ostracion rhinorhynchos Rhynchostracion nasus Tetrosomus gibbosus Tetrosomus reipublicae Paguridae Paguridae sp. Pylopaguropsis zebra Spiropagurus fimbriatus Palinuridae Palinuridae sp. Panulirus ornatus Panulirus versicolor Pinguipedidae Parapercis sp. Parapercis alboguttata Common Name - Binomial Perinereis vancaurica Platynereis antipoda Platynereis polyscalma Platynereis uniseris Pseudonereis anomala Pseudonereis trimaculata Pomacanthidae chaetodontoplus sp. Chaetodontoplus duboulayi Chaetodontoplus mesoleucus Chaetodontoplus personifer Pomacanthus sp. Pomacanthus imperator Pomacanthus semicirculatus Pomacanthus sexstriatus Common Name - scribbled angelfish vermiculate angelfish yellowtail angelfish emperor angelfish blue angelfish sixband angelfish App 3: Identification of potential species pool 213 Binomial Diopatra amboinensis Diopatra gigova Diopatra maculata Eunice afra Eunice antennata Eurythoe complanata Harmothoe dictyophora Hololepidella nigropunctata Iphione muricata Iphione ovata Leonnates indicus Leonnates stephensoni Lepidonotus carinulatus Lysidice ninetta Marphysa bifurcata Neanthes cricognatha Neanthes dawydovi Neanthes unifasciata Nereis bifida Nereis denhamensis Nereis heirissonensis Onuphis holobranchiata Palola siciliensis Perinereis amblyodonta Perinereis helleri Perinereis nigropunctata Perinereis obfuscata Perinereis suluana Common Name threespot angelfish keyhole angelfish blackaxil puller stoutbody puller green puller smoky puller whitetail puller doublebar chromis blue-green puller Weber's puller West Australian puller bengal sergeant banded sergeant scissortail sergeant blackspot sergeant Indo-Pacific sergeant staghorn damsel ternate damselfish blackbanded damsel Clark's anemonefish pink anemonefish Australian anemonefish biglip damsel blue demoiselle Binomial Chrysiptera tricincta Dascyllus aruanus Dascyllus reticulatus Dascyllus trimaculatus Dischistodus darwiniensis Dischistodus perspicillatus Dischistodus prosopotaenia Hemiglyphidodon plagiometopon Neoglyphidodon melas Neoglyphidodon nigroris Neopomacentrus azysron Neopomacentrus cyanomos Neopomacentrus filamentosus Neopomacentrus taeniurus Plectroglyphidodon dickii Common Name threeband damselfish banded humbug headband humbug threespot humbug banded damsel white damsel honeyhead damsel lagoon damsel black damsel scarface damsel yellowtail demoiselle regal demoiselle brown demoiselle freshwater demoiselle Dick's damsel App 3: Identification of potential species pool 214 Binomial Pomacanthidae sp. Apolemichthys trimaculatus Centropyge tibicen Pomacentridae Chromis sp. Chromis atripectoralis Chromis chrysura Chromis cinerascens Chromis fumea Chromis margaritifer Chromis opercularis Chromis viridis Chromis weberi Chromis westaustralis Pomacentridae sp. Abudefduf bengalensis Abudefduf septemfasciatus Abudefduf sexfasciatus Abudefduf sordidus Abudefduf vaigiensis Amblyglyphidodon curacao Amblyglyphidodon ternatensis Amblypomacentrus breviceps Amphiprion clarkii Amphiprion perideraion Amphiprion rubrocinctus Cheiloprion labiatus Chrysiptera cyanea Common Name Johnston damsel jewel damsel whiteband damsel alexander's damsel Ambon damsel neon damsel muddy damsel Miller's damsel lemon damsel blue-scribbled damsel goldback damsel peacock damsel princess damsel gulf damsel yellowtip gregory pacific gregory dusky gregory western gregory bluntsnout gregory glasseye lunartail bigeye spotted bigeye purplespotted bigeye Binomial Congrogadus spinifer Congrogadus subducens Pseudochromis sp. Pseudochromis fuscus Pseudochromis howsoni Pseudochromis marshallensis Pseudochromis quinquedentatus Pseudochromis reticulatus Pseudochromis wilsoni Rhinidae Rhynchobatus sp. Rhynchobatus australiae Rhynchobatus palpebratus Rhynhcobatus laevis Rhinidae sp. Common Name spiny eel blenny carpet eel blenny dusky dottyback Howson's dottyback marshall dottyback spotted dottyback reticulate dottyback yellowfin dottyback bottlenose wedgefish eyebrow wedgefish smoothnose wedgefish App 3: Identification of potential species pool 215 Binomial Plectroglyphidodon johnstonianus Plectroglyphidodon lacrymatus Plectroglyphidodon leucozona Pomacentrus alexanderae Pomacentrus amboinensis Pomacentrus coelestis Pomacentrus limosus Pomacentrus milleri Pomacentrus moluccensis Pomacentrus nagasakiensis Pomacentrus nigromanus Pomacentrus pavo Pomacentrus vaiuli Pristotis obtusirostris Stegastes apicalis Stegastes fasciolatus Stegastes nigricans Stegastes obreptus Stegastes punctatus Priacanthidae Priacanthus sp. Priacanthus blochii Priacanthus hamrur Priacanthus macracanthus Priacanthus tayenus Pseudochromidae Congrogadus sp. Common Name bowmouth guitarfish Bleeker's parrotfish pink-margined parrotfish steephead parrotfish knothead parrotfish raggedfin parrotfish greenfin parrotfish chameleon parrotfish bluebridle parrotfish yellowfin parrotfish whitespot parrotfish sixband parrotfish bluebarred parrotfish violetline parrotfish swarthy parrotfish darkcap parrotfish greencheek parrotfish palenose parrotfish surf parrotfish blackvein parrotfish Schlegel's parrotfish longnose parrotfish Binomial Sarda australis Sarda orientalis Scomberomorus sp. Scomberomorus commerson Scomberomorus munroi Scomberomorus queenslandicus Scombridae sp. Acanthocybium solandri Auxis thazard Cybiosarda elegans Euthynnus affinis Grammatorcynus bicarinatus Grammatorcynus bilineatus Gymnosarda unicolor Katsuwonus pelamis Common Name Australian bonito striped bonito Spanish mackerel spotted mackerel school mackerel wahoo frigate tuna leaping bonito mackerel tuna shark mackerel scad mackerel dogtooth tuna skipjack tuna App 3: Identification of potential species pool 216 Binomial Rhina ancylostoma Scaridae Chlorurus sp. Chlorurus bleekeri Chlorurus capistratoides Chlorurus microrhinos Chlorurus oedema Chlorurus rhakoura Chlorurus sordidus Scarus sp. Scarus chameleon Scarus dimidiatus Scarus flavipectoralis Scarus forsteni Scarus frenatus Scarus ghobban Scarus globiceps Scarus niger Scarus oviceps Scarus prasiognathos Scarus psittacus Scarus rivulatus Scarus rubroviolaceus Scarus schlegeli Scaridae sp. Hipposcarus longiceps Scombridae Sarda sp. Common Name mouth mackerel northern bluefin tuna moon jellyfish blue blubber mauve stinger brown jellyfish ovalbone cuttlefish broadclub cuttlefish papuan cuttlefish pharaoh cuttlefish smith’s cuttlefish peacock rockcod brownbarred rockcod bluespotted rockcod Binomial Cephalopholis miniata Cephalopholis sonnerati Cephalopholis urodeta Epinephelus sp. Epinephelus amblycephalus Epinephelus areolatus Epinephelus bilobatus Epinephelus bleekeri Epinephelus chlorostigma Epinephelus coeruleopunctatus Epinephelus coioides Epinephelus corallicola Epinephelus fasciatus Epinephelus fuscoguttatus Epinephelus lanceolatus Common Name coral rockcod tomato rockcod flagtail rockcod banded grouper yellowspotted rockcod frostback rockcod duskytail grouper brownspotted grouper whitespotted grouper goldspotted rockcod coral grouper blacktip rockcod flowery rockcod Queensland groper App 3: Identification of potential species pool 217 Binomial Rastrelliger kanagurta Thunnus orientalis Scyphozoa Scyphozoa sp. Aurelia aurita Catostylus mosaicus Cephea cephea Chrysaora kynthia Chrysaora pentastoma Crambione mastigophora Cyanea annaskala Cyanea buitendijki Cyanea mjobergi Pelagia noctiluca Phyllorhiza pacifica Phyllorhiza punctata Sepiidae Sepia sp. Sepia elliptica Sepia latimanus Sepia papuensis Sepia pharaonis Sepia smithi Serranidae Cephalopholis sp. Cephalopholis argus Cephalopholis boenak Cephalopholis cyanostigma Common Name striped grouper snubnose grouper highfin grouper blackspotted rockcod birdwire rockcod Rankin cod specklefin grouper camouflage grouper longfin rockcod chinaman rockcod sixbar grouper greasy rockcod potato rockcod passionfruit coral trout bluespotted coral trout common coral trout barcheek coral trout whitelined rockcod longfin perch sunrise perch barramundi cod barred soapfish lilac-tip basslet honeycomb podge rainfordia oval rockcod Binomial Variola albimarginata Variola louti Siganidae Siganus sp. Siganus argenteus Siganus canaliculatus Siganus corallinus Siganus doliatus Siganus fuscescens Siganus javus Siganus lineatus Siganus punctatissimus Siganus punctatus Siganus trispilos Siganus virgatus Common Name white-edge coronation trout yellowedge coronation trout forktail rabbitfish whitespotted rabbitfish coral rabbitfish bluelined rabbitfish black rabbitfish Java rabbitfish goldlined rabbitfish finespotted rabbitfish spotted rabbitfish threespot rabbitfish doublebar rabbitfish App 3: Identification of potential species pool 218 Binomial Epinephelus latifasciatus Epinephelus macrospilos Epinephelus maculatus Epinephelus malabaricus Epinephelus merra Epinephelus multinotatus Epinephelus ongus Epinephelus polyphekadion Epinephelus quoyanus Epinephelus rivulatus Epinephelus sexfasciatus Epinephelus tauvina Epinephelus tukula Plectropomus sp. Plectropomus areolatus Plectropomus laevis Plectropomus leopardus Plectropomus maculatus Serranidae sp. Anyperodon leucogrammicus Caprodon longimanus Caprodon schlegelii Chromileptes altivelis Diploprion bifasciatum Pseudanthias rubrizonatus Pseudogramma polyacanthus Rainfordia opercularis Triso dermopterus Common Name foxface sharpfin barracuda great barracuda blackspot barracuda Heller's barracuda pickhandle barracuda snook yellowtail barracuda striped barracuda military barracuda blackfin barracuda shortfin saury threadfin saury gracile saury grey saury longfin saury clouded saury largescale saury wanieso saury twospot lizardfish banded lizardfish blackshoulder lizardfish Indian lizardfish Binomial Synodus jaculum Synodus macrops Synodus sageneus Synodus similis Synodus variegatus Synodontidae sp. Trachinocephalus trachinus Tetraodontidae Arothron sp. Arothron caeruleopunctatus Arothron hispidus Arothron manilensis Arothron mappa Arothron nigropunctatus Arothron reticularis Common Name tailspot lizardfish triplecross lizardfish fishnet lizardfish streaky lizardfish variegated lizardfish painted grinner bluespotted puffer stars-and-stripes puffer narrowlined puffer scribbled puffer blackspotted puffer reticulate toadfish App 3: Identification of potential species pool 219 Binomial Siganus vulpinus Sphyraenidae Sphyraena sp. Sphyraena acutipinnis Sphyraena barracuda Sphyraena forsteri Sphyraena helleri Sphyraena jello Sphyraena novaehollandiae Sphyraena obtusata Sphyraena pinguis Sphyraena putnamae Sphyraena qenie Synodontidae Saurida sp. Saurida argentea Saurida filamentosa Saurida gracilis Saurida grandisquamis Saurida longimanus Saurida nebulosa Saurida undosquamis Saurida wanieso Synodus sp. Synodus binotatus Synodus dermatogenys Synodus hoshinonis Synodus indicus Common Name starry puffer crowned toby clown toby ocellate toby smooth golden toadfish rough golden toadfish silver toadfish brownback toadfish ferocious puffer common toadfish rusty-spotted toadfish yelloweye toadfish weeping toadfish fringe-gill toadfish Binomial Tylerius spinosissimus Teuthida Teuthida sp. Sepioteuthis lessoniana Uroteuthis (Photololigo) chinensis Uroteuthis (Photololigo) edulis Triglidae Triglidae sp. Chelidonichthys kumu Lepidotrigla argus Lepidotrigla grandis Lepidotrigla russelli Lepidotrigla vanessa Pterygotrigla elicryste Common Name finespine pufferfish northern calamari mitre squid swordtip squid red gurnard eye gurnard little red gurnard smooth gurnard butterfly gurnard dwarf gurnard 220 App 3: Identification of potential species pool Binomial Arothron stellatus Canthigaster sp. Canthigaster axiologus Canthigaster callisternus Canthigaster rivulata Lagocephalus sp. Lagocephalus inermis Lagocephalus lunaris Lagocephalus sceleratus Lagocephalus spadiceus lagocephalus suezensis Tetraodontidae sp. Feroxodon multistriatus Tetractenos hamiltoni Torquigener pallimaculatus Torquigener parcuspinus Torquigener pleurogramma Torquigener tuberculiferus