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A Comparison of Megafaunal Biodiversity in Two Contrasting Submarine Canyons on Australia's Southern Continental Margin

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A Comparison of Megafaunal Biodiversity in Two Contrasting Submarine Canyons on Australia's Southern Continental Margin A comparison of megafaunal biodiversity in two contrasting submarine canyons on Australia’s southern continental margin David R. Currie and Shirley J. Sorokin SARDI Publication No. F2010/000981-1 SARDI Research Report Series No. 519 SARDI Aquatic Sciences PO Box 120 Henley Beach SA 5022 February 2011 Report to the South Australian Department of Environment and Natural Resources A comparison of megafaunal biodiversity in two contrasting submarine canyons on Australia’s southern continental margin Report to the South Australian Department of Environment and Natural Resources David R. Currie and Shirley J. Sorokin SARDI Publication No. F2010/000981-1 SARDI Research Report Series No. 519 February 2011 Currie, D.R. and Sorokin, S.J. (2011) Canyon biodiversity This Publication may be cited as: Currie, D.R and Sorokin, S.J (2011). A comparison of megafaunal biodiversity in two contrasting submarine canyons on Australia’s southern continental margin. Report to the South Australian Department of Environment and Natural Resources. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2010/000981-1. SARDI Research Report Series No. 519. 49pp. South Australian Research and Development Institute SARDI Aquatic Sciences 2 Hamra Avenue West Beach SA 5024 Telephone: (08) 8207 5400 Facsimile: (08) 8207 5406 http://www.sardi.sa.gov.au DISCLAIMER The authors warrant that they have taken all reasonable care in producing this report. The report has been through the SARDI Aquatic Sciences internal review process, and has been formally approved for release by the Chief, Aquatic Sciences. Although all reasonable efforts have been made to ensure quality, SARDI Aquatic Sciences does not warrant that the information in this report is free from errors or omissions. SARDI Aquatic Sciences does not accept any liability for the contents of this report or for any consequences arising from its use or any reliance placed upon it. © 2011 SARDI This work is copyright. Apart from any use as permitted under the Copyright Act 1968 (Cth), no part may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owner. Neither may information be stored electronically in any form whatsoever without such permission. Printed in Adelaide: February 2011 SARDI Publication No. F2010/000981-1 SARDI Research Report Series No. 519 Author(s): Dr David R. Currie and Ms Shirley J. Sorokin Reviewer(s): Dr Nathan J. Bott and Ms. Sonja L. Hoare Approved by: Dr Jason E. Tanner Principal Scientist – Marine Environment & Ecology Signed: Date: 1 February 2011 Distribution: South Australian Department of Environment and Natural Resources, SAASC Library and University of Adelaide Library Circulation: Public Domain SARDI Aquatic Sciences Report - Page I Currie, D.R. and Sorokin, S.J. (2011) Canyon biodiversity TABLE OF CONTENTS LIST OF FIGURES ................................................................................................................... III LIST OF TABLES..................................................................................................................... III LIST OF APPENDICES ............................................................................................................IV EXECUTIVE SUMMARY ........................................................................................................... 1 1 INTRODUCTION ................................................................................................................ 3 1.1 BACKGROUND................................................................................................................................................. 3 1.2 OBJECTIVES .................................................................................................................................................... 3 2 METHODS.......................................................................................................................... 5 2.1 FIELD SAMPLING ............................................................................................................................................. 5 2.2 LABORATORY PROCESSING ............................................................................................................................. 6 2.3 STATISTICAL ANALYSES.................................................................................................................................. 6 2.3.1 Univariate patterns............................................................................................................................... 6 2.3.2 Environmental parameters ...................................................................................................................6 2.3.3 Multivariate patterns ............................................................................................................................ 6 3 RESULTS........................................................................................................................... 8 3.1 ENVIRONMENTAL CHARACTERISTICS .............................................................................................................. 8 3.1.1 Bathymetry............................................................................................................................................ 8 3.1.2 Sediment composition and structure..................................................................................................... 8 3.1.3 Oceanography....................................................................................................................................... 9 3.2 EPIFAUNAL COMPOSITION ............................................................................................................................... 9 3.3 SPATIAL PATTERNS IN SPECIES RICHNESS AND BIOMASS ............................................................................... 10 3.4 ENVIRONMENTAL LINKAGES - RICHNESS AND BIOMASS ................................................................................ 10 3.5 EPIFAUNAL COMMUNITY STRUCTURE ........................................................................................................... 11 3.6 ENVIRONMENTAL LINKAGES – COMMUNITY STRUCTURE .............................................................................. 12 4 DISCUSSION ................................................................................................................... 13 REFERENCES ........................................................................................................................ 17 AKNOWLEDGEMENTS .......................................................................................................... 21 SARDI Aquatic Sciences Report - Page II Currie, D.R. and Sorokin, S.J. (2011) Canyon biodiversity LIST OF FIGURES Figure 1. Map showing the locations of Bonney and du Couedic canyons (unfilled rectangles) on the south-east continental margin. Contour lines presented follow 100 m depth intervals. .. 22 Figure 2. Bathymetric map of du Couedic Canyon showing the locations of 5 survey sites sampled for macro-epibenthos, sediments and near-bed water properties. Labels denote location relative to the main canyon axis (DCC = du Couedic Centre) and sampling depth in metres (100, 200, 500, 1000, 1500). ........................................................................................ 23 Figure 3. Bathymetric map of Bonney Canyon showing the locations of 6 survey sites sampled for macro-epibenthos, sediments and near-bed water properties. Labels denote location relative to the main canyon axis (BC = Bonney Centre) and sampling depth in metres (100, 200, 500, 1000, 1500, 2000)............................................................................................................ 24 Figure 4. Plots of (a) mean wet weight, (b) total number of species of each major phylum collected during the survey, and (c) total number of sites (out of 11) at which specimens belonging to each major phylum were collected. Values for each variable are shown as percentages above each bar.................................................................................................... 25 Figure 5. Total (a) number of species, and (b) wet weights of macro-epibenthos collected during sled tows at 11 depth-stratified sampling stations at Bonney and du Couedic canyons. 26 Figure 6. Dendrogram and non-metric MDS ordination of epifaunal community structure at 11 depth-stratified sampling stations at Bonney and du Couedic canyons. Sampling depths are represented by different symbols (upright triangle = 100 m, diamond = 200 m, circle = 500 m, inverted triangle = 1000 m, square = 1500 m, plus = 2000 m) and canyon locations by different shades of fill (black = Bonney, white = du Couedic). Three station groupings are identified at the 5% Bray-Curtis similarity level (dotted line): shelf (100-200 m), upper slope (500 m) and mid- slope (1000-2000 m)................................................................................................................ 27 LIST OF TABLES Table 1. Summary of environmental factors at 11 epibenthic sampling sites at Bonney and du Couedic canyons. .................................................................................................................... 28 Table 2. Spearman’s rank correlation coefficients between epifaunal richness and biomass and adjacent environmental conditions at 11 depth-stratified sampling stations at Bonney (B)
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