GEOSCIENCE AUSTRALIA Seabed Habitats and Hazards of the Joseph Bonaparte Gulf and Timor Sea, Northern Australia Rachel Przeslawski, James Daniell, Tara Anderson, J. Vaughn Barrie, Andrew Heap, Michael Hughes, Jin Li, Anna Potter, Lynda Radke, Record Justy Siwabessy, Maggie Tran, Tanya Whiteway and Scott Nichol 2011/40 GeoCat # 72805 APPLYING GEOSCIENCE TO AUSTRALIA’S MOST IMPORTANT CHALLENGES Seabed Habitats and Hazards of the Joseph Bonaparte Gulf and Timor Sea, Northern Australia GEOSCIENCE AUSTRALIA RECORD 2011/40 by Rachel Przeslawski1, James Daniell1, Tara Anderson1, J. Vaughn Barrie2, Andrew Heap1, Michael Hughes3, Jin Li1, Anna Potter1, Lynda Radke1, Justy Siwabessy1, Maggie Tran1, Tanya Whiteway1, Scott Nichol1 1. Geoscience Australia, GPO Box 378, Canberra, ACT 2601 2. Geological Survey of Canada – Pacific, Natural Resources Canada, PO Box 6000, Sidney British Columbia, Canada 3. Current Address: Office of the Chief Scientist, GPO Box 9839, Canberra, ACT 2601 Department of Resources, Energy and Tourism Minister for Resources and Energy: The Hon. Martin Ferguson, AM MP Secretary: Mr Drew Clarke Geoscience Australia Chief Executive Officer: Dr Chris Pigram © Commonwealth of Australia (Geoscience Australia) 2011 With the exception of the Commonwealth Coat of Arms and where otherwise noted, all material in this publication is provided under a Creative Commons Attribution 3.0 Australia Licence (http://creativecommons.org/licenses/by/3.0/au/) Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not solely rely on this information when making a commercial decision. ISSN 1448-2177 ISBN 978-1-921954-51-1 GeoCat # 72805 Bibliographic reference: Przeslawski, R., Daniell, J., Anderson, T., Barrie, J.V., Heap, A., Hughes, M., Li, J., Potter, A., Radke, R., Siwabessy, J., Tran, M., Whiteway, T., Nichol, S. 2011. Seabed Habitats and Hazards of the Joseph Bonaparte Gulf and Timor Sea, Northern Australia. Geoscience Australia, Record 2011/40, 69pp. Contents List of Figures....................................................................................................................iv List of Tables.......................................................................................................................v Executive Summary...........................................................................................................vi Acronyms ..........................................................................................................................vii Acknowledgements .........................................................................................................viii 1. Introduction.....................................................................................................................1 2. Habitats & Communities ................................................................................................6 2.1 Regional Summary of Habitats & Communities ........................................................................6 2.2 Habitat Classifications ................................................................................................................8 2.3 Regional-scale Geomorphology................................................................................................11 2.4 Local-Scale Geomorphology ....................................................................................................14 2.5 Biophysical Characterisation of Geomorphic Features.............................................................18 2.5.1 Banks..................................................................................................................................20 2.5.2 Terraces .............................................................................................................................21 2.5.3 Ridges.................................................................................................................................22 2.5.4 Plains .................................................................................................................................23 2.5.5 Valleys................................................................................................................................24 2.6 Distinctive Habitats & Communities ........................................................................................25 2.6.1 Sponge, Infaunal, and Coral Communities........................................................................25 2.6.2 Pockmark Communities .....................................................................................................26 2.7 Significant Habitats & Communities ........................................................................................26 2.8 Relationship between Biology and the Environment................................................................30 3. Potential Hazards..........................................................................................................37 3.1 Slope Instability ........................................................................................................................39 3.2 Fluid and Gas Expulsion...........................................................................................................40 3.3 Elevated features / Hard ground................................................................................................43 3.4 Erosion at the Seabed................................................................................................................44 3.5 Oceanographic Hazards at the Sea Surface...............................................................................45 4. Biophysical Processes & Conceptual Models ...........................................................49 5. Conclusions ..................................................................................................................59 6. References ....................................................................................................................61 Appendix A: Data Sources...............................................................................................70 Appendix B: Spatial interpolation of gravel and mud content in the JBG-TS .............72 Appendix C: Ecology........................................................................................................74 Appendix D: Geomorphology & Sedimentology.......................................................... 104 Appendix E: Geochemistry............................................................................................ 108 Appendix F: Geophysics................................................................................................ 119 Appendix G: Physical Oceanography........................................................................... 129 Appendix H: GIS Data.....................................................................................................153 Instructions for the CD-ROM ......................................................................................... 156 iii List of Figures 1. Introduction.....................................................................................................................1 Figure 1.1: Petroleum industry activity in the Joseph Bonaparte Gulf and Timor Sea region. ...........2 Figure 1.2: Bioregionalisations for the JBG based on IMCRA 4.0 .....................................................3 2. Habitats & Communities ................................................................................................6 Figure 2.1: Key broadscale geomorphic features and ocean circulation patterns within the JBG-TS and adjacent region for wet (January) and dry (July) seasons.. ....................................................7 Figure 2.2: Maps of biodiversity have been developed for Australia based on data from (a-b) demersal fish, (c) brittlestars, and (d) tropical and sub-tropical sponges......................................9 Figure 2.3: A habitat classification system based on regional-scale derivations of seascapes from combined interpolation of seven environmental factors in the JBG-TS .....................................10 Figure 2.4: Palaeo-shoreline maps from the JBG-TS, with time series indicated on the line graph..12 Figure 2.5: Map of JBG-TS geomorphology in the region of interest based on Harris et al (2005) and Heap and Harris (2008)........................................................................................................13 Figure 2.6: Geomorphic features from GA-0322 and GA-0325 survey areas...................................15 Figure 2.7: Geomorphic features from GA-0322 and GA-0325 survey area A.................................16 Figure 2.8: Geomorphic features from GA-0322 and GA-0325 survey area B.................................16 Figure 2.9: Geomorphic features from GA-0322 and GA-0325 survey area C.................................17 Figure 2.10: Geomorphic features from GA-0322 and GA-0325 survey area D...............................17 Figure 2.11: The number of (a) epifaunal and (b) infaunal species collected from the survey areas, classified by geomorphic feature type. .......................................................................................19 Figure 2.12: Representative images of banks. ...................................................................................20