A GIS Study of Australia s Marine Benthic Habitats

Transcription

1 School of Geography and Environmental Studies University of Tasmania A GIS Study of Australia s Marine Benthic Habitats by Robin J. Beaman, BSc, BAntSt(Hons) Submitted in fulfillment of the requirements for the degree of Doctor of Philosophy November 2005

2 Declaration This thesis contains no material that has been accepted for the award of any other degree or diploma in any other tertiary institution, and to the best of my knowledge contains no copy, paraphrase or material previously published or written by another person, except where due reference is given in the text.. Robin J. Beaman Date 10 November 2005 Authority of Access This thesis may be made available for loan and limited copying in accordance with the Copyright Act Robin J. Beaman Date 10 November 2005 ii

3 Supporting Publications Some of the work presented in this thesis appears in peer-reviewed publications. Where substantial parts of these papers are reproduced in this thesis, it is in all cases my own original contribution to those papers that is transposed into the thesis. The papers directly related to the project work of this thesis are: Beaman, R.J., Daniell, J., Harris, P.T., Geology-benthos relationships on a temperate rocky bank, eastern Bass Strait, Australia. Marine and Freshwater Research 56, Beaman, R.J., Harris, P.T., Seafloor morphology and acoustic facies of the George V Land shelf. Deep-Sea Research Part II 50 (8-9), Beaman, R.J., Harris, P.T., Bioregionalisation of the George V Shelf, East Antarctica. Continental Shelf Research 25, Beaman, R.J., Harris, P.T., in review. Geophysical variables as predictors of megabenthos assemblages from the northern Great Barrier Reef, Australia. In: B.J. Todd and H.G. Greene (Editors), Marine Geological and Benthic Habitat Mapping. Special Publication. Geological Association of Canada, St John's, Canada. Harris, P.T., Beaman, R.J., Processes controlling the formation of the Mertz Drift, George Vth continental shelf, East Antarctica: evidence from 3.5 khz sub-bottom profiling and sediment cores. Deep-Sea Research Part II 50 (8-9), Harris, P.T., Brancolini, G., Armand, L., Brusetti, M., Beaman, R.J., Giorgetti, G., Presti, M., Trincardi, F., Continental shelf drift deposit indicates non-steady state Antarctic bottom water production in the Holocene. Marine Geology 179 (1-2), 1-8. iii

4 Quotes Il faut aller voir - We must go and see. Jacques-Yves Cousteau The real voyage of discovery does not consist of seeking new landscapes, but in having new eyes. Marcel Proust The very deep did rot: O Christ! That ever this should be! Yea, slimy things did crawl with legs Upon the slimy sea. Samuel Coleridge iv

5 Abstract Continental shelf waters are subject to the greatest impact by humans. If marine ecosystems are to be efficiently managed and protected from the adverse effects of human activities, then identification of the types of marine habitats and the communities they contain is required. Research cruise data and existing data were collected at three diverse study sites on polar, temperate and tropical continental shelves within Australia's Exclusive Economic Zone (EEZ). This project conducted a multi-disciplinary analysis of satellite imagery, multibeam sonar, seismic profiles, oceanographic data, underwater video, and the results of sediment sampling. A Geographic Information System (GIS) was utilised to model the spatial boundaries of the physical and biological datasets. Spatial and multivariate statistical analyses were conducted on the GIS models and datasets to explore the relationships between abiotic and biotic patterns. GIS was used to map the spatial distribution of benthic habitats at each study site within a hierarchical context. The East Antarctic continental shelf has had few studies examining the macrobenthos structure or relating biological communities to the abiotic environment. On the George V Shelf, GIS was used to map the geomorphology, surficial sediment and near-seabed water mass boundaries. A study of underwater photographs and the results of biological sampling provided information to infer the dominant trophic structure of benthic communities within geomorphic features. A hierarchical method of benthic habitat mapping was applied to the Geomorphic Unit and Biotope levels at the local (10s of km) scale. The study revealed that mud content, iceberg scour, and oceanic currents are the likely dominant abiotic factors in the broad-scale distribution of macrofauna on the George V Shelf. To better understand the relationships between the geology of the seabed and associated biological communities, a multibeam sonar survey was conducted over New Zealand Star Bank, eastern Bass Strait, Australia. Through spatial and multivariate analyses of surficial sediment composition and underwater video, the biological assemblage patterns were related to the variation in geomorphology and substrate. A hierarchical method of benthic habitat mapping was applied to the Secondary Biotope and Biological Facies levels at the site (<10 km) scale. The major differences which control the distribution of biological communities in the New Zealand Star Bank area appear to be related to variations in substrate. v

6 To help answer the question whether geophysical data from habitats can be used to predict the occurrence of benthic biodiversity, a multibeam sonar survey was conducted in the northern Great Barrier Reef - Gulf of Papua region. Multivariate statistical analyses were applied to the biological and physical datasets to determine patterns in the distribution of megabenthos, and the relationship with abiotic variables. A hierarchical method of benthic habitat mapping was applied to the Secondary Biotope and Biological Facies levels at the site (<10 km) scale. The combination of substrate type, sedimentary dynamics and physical processes related to nearseabed currents appear to be a dominant control on the benthic communities in the northern Great Barrier Reef - Gulf of Papua region. Benthic habitat mapping plays a vital part in understanding marine ecosystems and the processes which influence the spatial distribution of benthos. The results of this research have made significant in-roads in the development of a framework for ecosystem-based management of the study areas, the contribution to the ongoing bioregionalisation of Australia, and through an examination of the use of geophysical proxies for the occurrence of biological assemblages, which are fundamental to the establishment of Marine Protected Areas. vi

7 Acknowledgements A PhD is not undertaken in isolation and there are many people to thank for the varied contributions they have made on both professional and personal terms. This PhD project involved three research cruises to very different parts of the world, and could not have been possible without the exceptional abilities of my research supervisor and colleague Peter Harris from Geoscience Australia. I am truly grateful that he gave me the opportunity to take part in these cruises and present the results in this thesis. For the polar case study, I thank Amy Leventer for the use of multibeam bathymetry and biological data from the NBP0101 expedition to East Antarctica, and give a special thank you to Captain Joseph Borkowski and crew of the RVIB Nathaniel B. Palmer for making this cruise so special. The seismic profiles, sediment grabs and underwater photography were obtained under the WEGA project. Thanks also to Rick Porter-Smith for helping with the bathymetric model, and Guy Williams and Nathan Bindoff of the Antarctic Co-operative Research Centre for supplying summer and winter oceanographic data for the George V Shelf. The temperate case study utlised the Hydrographic Ship HMAS Melville as a co-operative survey between Geoscience Australia and the Royal Australian Navy. I thank Commander John Maschke and the crew of the Melville for their professionalism and assistance in conducting the survey, and hosting myself and James Daniell for the period of the voyage. Thanks also to the RAN Hydrographic Service for supplying the multibeam bathymetry data, and to James Cook University - Cairns Campus for the use of the Advanced Analytical Centre for processing sediment grab samples. The tropical case study was conducted as Geoscience Australia Survey 234 on the RV Franklin. I would like to offer special thanks to Captain Ian Taylor and crew of the Franklin for helping make the survey such as productive one. Thanks go to James Daniell for processing the multibeam data, and to James Cook University - Cairns Campus for the use of the media laboratory to process underwater video. I could not have had better university support through my academic supervisor Richard Coleman at the University of Tasmania. Despite the fact that most of this PhD study was conducted while I was an external student living in Cairns, he helped me overcome the geographic distance to give me his time and support while making me feel part of the University of Tasmania community. vii

8 To my fellow roommates during my first two years at the Centre for Spatial Information Science, Chris Watson, Matt King and Rob Musk, thank you for the coffee and discussions. I am especially grateful for the friendship and support from fellow PhD student and housemate Andrew Roberts. Finally, I would like to give thanks to my family, Greg, Jodie, Brad and Angela for giving moral support as I worked through the latter part of the project as an external student in Cairns. In the last year of my study I met a wonderful lady, Diane. Thank you for being such a good friend and being so patient through this last phase. viii

9 Contents Cover page Declaration and Authority of Access Supporting Publications Quotes Abstract Acknowledgements Contents i ii iii iv v vii ix Chapter 1 Introduction Overview Environmental management Bioregionalisation of Australia Geophysical proxies Aims and objectives Structure of thesis References 11 Chapter 2 Polar Case Study Introduction Materials and methods Study area - glacial and sea ice setting Study area - bathymetric and oceanographic setting Bathymetry data Sediment data Oceanographic data Biological data Results Geomorphology Surficial sediment Near-seabed oceanography Macrobenthos Biotopes 'Diverse inner shelf' 'Diverse canyon' 44 ix

10 'Suspension-feeder canyon' 'Barren basin' 'Deposit-feeder basin' 'Suspension-feeder drift' 'Detritus-feeder basin' 'Suspension-feeder bank' 'Diverse bank' 'Diverse ridge' 'Transitional sill' 'Oceanic shelf edge' Discussion Environment-benthos relationships Depth of the seabed and the pattern of iceberg grounding on the shelf Influence of a variable Mertz Glacier Tongue grounding zone Distribution of substrate in the basin below the influence of icebergs Oceanic and shelf current circulation patterns Dominant abiotic processes on the George V Shelf Conclusions References 59 Chapter 3 Temperate Case Study Introduction Materials and methods Study area Bathymetry data Sediment data Underwater video data Results Geomorphology Surficial sediment Environmental variables Secondary Biotopes and Biological Facies 'High-relief granite' and 'deep reef/urchin barrens' 'Low-relief sandstone' and 'patchy large sponges' 'Quartzose sand' and 'sparse small sponges' 'Muddy sand' and 'bioturbate' Discussion 88 x

11 3.4.1 Geology-benthos relationships Hard-ground features related to granite outcrops Unconsolidated sediment on a flat seabed Unconsolidated sediment on a low-relief seabed Fish-benthos relationships Assessment techniques Conclusion References 94 Chapter 4 Tropical Case Study Introduction Materials and methods Study areas Bathymetry data Underwater video data Environmental data Results Geomorphology Megabenthos Environmental variables BIO-ENV procedure Secondary Biotopes and Biological Facies Area A - 'low-relief limestone' and 'mixed garden' Area A - 'infilled channel' and 'patchy softcoral' Area A - 'muddy sand' and 'bioturbate' Area B - 'relict reef' and 'mixed garden' Area B - 'live reef' and 'hardcoral' Area B - 'platform/valley floor' and 'sparse fauna' Area B - 'valley side' and 'patchy softcoral' Discussion Limitations of BIO-ENV procedure Geology-benthos relationships Assessment techniques Conclusion References 127 xi

12 Chapter 5 Conclusions Key findings in terms of the project objectives Physical environment of the study sites Macrobenthos assemblages Geophysical and biological community relationships Recommendations Multibeam sonar Underwater video Sediment grabs GIS Proxies Habitat definition Maps Linking science and management Summary of research References 145 Appendix A Primer 146 A.1 Introduction 146 A.2 Bray-Curtis similarity 146 A.3 Cluster analysis 148 A.4 Non-metric, multi-dimensional scaling 150 A.5 Principal component analysis 152 A.6 BIO-ENV 154 A.7 References 156 Appendix B CDROM of Extra Material Flythrough movies Images from research cruises Peer-reviewed publications Seminars from research Viewing software xii