Resilience and Resistance of Aquatic Plant Communities Downstream of Lock 1 in the Murray River Jason M Nicol, Susan L Gehrig, Kate A Frahn and Arron D Strawbridge Goyder Institute for Water Research Technical Report Series No. 13/5 www.goyderinstitute.org Goyder Institute for Water Research Technical Report Series ISSN: 1839-2725 The Goyder Institute for Water Research is a partnership between the South Australian Government through the Department for Environment, Water and Natural Resources, CSIRO, Flinders University, the University of Adelaide and the University of South Australia. The Institute will enhance the South Australian Government’s capacity to develop and deliver science-based policy solutions in water management. It brings together the best scientists and researchers across Australia to provide expert and independent scientific advice to inform good government water policy and identify future threats and opportunities to water security. The following Associate organisations produced this report: Enquires should be addressed to: Goyder Institute for Water Research Level 1, Torrens Building 220 Victoria Square, Adelaide, SA, 5000 tel: 08-8303 8952 e-mail: [email protected] Citation Nicol JM, Gehrig SL, Frahn KA and Strawbridge AD (2013) Resilience and resistance of aquatic plant communities downstream of Lock 1 in the Murray River. Goyder Institute for Water Research Technical Report Series No. 13/5, Adelaide, South Australia. Copyright © 2013 South Australian Research and Development Institute, Aquatic Sciences. To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of the South Australian Research and Development Institute, Aquatic Sciences. Disclaimer The Participants advise that the information contained in this publication comprises general statements based on scientific research and does not warrant or represent the completeness of any information or material in this publication. Paricipants do not accept any liability for the contents of this report or for any consequences arising from its use or any reliance placed upon it. Table of Contents Table of Contents ..................................................................................................................................... I List of Figures ......................................................................................................................................... III List of Tables .......................................................................................................................................... IV List of Appendices ................................................................................................................................... V Acknowledgements ................................................................................................................................ VI Abstract ................................................................................................................................................... 7 Introduction ............................................................................................................................................ 9 Methods ................................................................................................................................................ 11 Study site ........................................................................................................................................... 11 Mannum to Blanchetown ............................................................................................................. 11 Lower Lakes ................................................................................................................................... 13 Hydrological conditions downstream of Lock 1 between 2007 and 2012 .................................... 15 Vegetation survey protocol .............................................................................................................. 19 Mannum to Blanchetown ............................................................................................................. 19 Lower Lakes ................................................................................................................................... 19 Plant identification and nomenclature ......................................................................................... 21 Data analysis ..................................................................................................................................... 21 Results ................................................................................................................................................... 22 Mannum to Blanchetown ................................................................................................................. 22 Wetlands ....................................................................................................................................... 23 River Murray Channel ................................................................................................................... 24 Lower Lakes-lake shores ................................................................................................................... 25 Lake Albert .................................................................................................................................... 25 Lake Alexandrina ........................................................................................................................... 26 Goolwa Channel ............................................................................................................................ 28 Lower Lakes-wetlands ....................................................................................................................... 29 Angas and Bremer Mouths ........................................................................................................... 29 Dunns Lagoon................................................................................................................................ 30 Goolwa Channel Drive Wetland .................................................................................................... 32 Hunters Creek ............................................................................................................................... 32 Poltalloch ...................................................................................................................................... 33 Point Sturt ..................................................................................................................................... 34 Discussion.............................................................................................................................................. 36 Nicol et al . 2012 I Further Studies .................................................................................................................................. 39 References ............................................................................................................................................ 41 Appendices ............................................................................................................................................ 49 Nicol et al . 2012 II List of Figures Figure 1: Wetland (yellow dots) and river (red dots) survey sites between Mannum and Blanchetown. ........................................................................................................................................ 12 Figure 2: Wetland (red dots) and lakeshore survey sites in Lake Alexandrina (yellow dots), Lake Albert (blue dots and Goolwa Channel (green dots). ........................................................................... 14 Figure 3: Water levels between August 2008 and August 2012 for Mannum (Town Wharf), Lake Alexandrina (Milang), Lake Albert (Meningie) and Goolwa Channel (Signal Point) (DEWNR 2013). ... 17 Figure 4: Surface water electrical conductivity (EC) between August 2008 and August 2012 for Mannum (Town Wharf), Lake Alexandrina (Milang), Lake Albert (Meningie) and Goolwa Channel (Signal Point) (DEWNR 2013). ............................................................................................................... 18 Figure 5: Vegetation surveying protocol for lake shore sites: plan view showing placement of quadrats relative to the shoreline. ....................................................................................................... 21 Figure 6: NMS ordination comparing the plant community through time at five elevations in the six sampled wetlands between Mannum and Blanchetown. .................................................................... 23 Figure 7: NMS ordination comparing the plant community through time at five elevations in the four sampled river sites between Mannum and Blanchetown. ................................................................... 24 Figure 8: NMS ordination comparing the plant community through time at six elevations (cm AHD) along the shoreline of Lake Albert. ....................................................................................................... 26 Figure 9: NMS ordination comparing the plant community through time at six elevations (cm AHD) along the shoreline of Lake