Vegetation Monitoring in the Goolwa-Clayton Weir Pool: 2009/2010
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Aquatic and littoral vegetation monitoring of Goolwa Channel 2009-10 Susan Gehrig and Jason Nicol SARDI Publication No. F2010/000383-1 SARDI Research Report Series No. 488 SARDI Aquatic Sciences PO Box 120 Henley Beach SA 5022 August 2010 Aquatic and littoral vegetation monitoring of Goolwa Channel 2009-10 Susan Gehrig and Jason Nicol SARDI Publication No. F2010/000383-1 SARDI Research Report Series No. 488 August 2010 This Publication may be cited as: Gehrig, S.L. and Nicol, J.M (2010). Aquatic and littoral vegetation monitoring of Goolwa Channel 2009-10. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2010/000383-1. SARDI Research Report Series No. 488. 22pp. 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. © 2010 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 without prior written permission from the authors. Printed in Adelaide: August 2010 SARDI Publication No. F2010/000383-1 SARDI Research Report Series No. 488 Author(s): Susan Gehrig and Jason Nicol Reviewer(s): Rod Ward and Chris Bice Approved by: Qifeng Ye Program Leader – Inland Waters & Catchment Ecology Signed: Date: 19 August 2010 Distribution: DENR, MDBA, SAMDBNRM Board, DFW, SAASC Library and University Of Adelaide Library Circulation: Public Domain Gehrig and Nicol (2010) Vegetation Condition Monitoring in Goolwa Channel 2009-2010 Page i ____________________________________________________________________________________________ Table of Contents Table of Contents.............................................................................................................................................. i List of Figures .................................................................................................................................................... i List of Tables...................................................................................................................................................... i List of Appendices ........................................................................................................................................... ii Acknowledgements ..........................................................................................................................................1 Executive Summary .........................................................................................................................................2 1. Introduction..................................................................................................................................................4 2. Methods.........................................................................................................................................................6 2.1. Study site ............................................................................................................................................ 6 2.2. Vegetation surveying protocol........................................................................................................ 6 2.3. Plant identification and nomenclature........................................................................................... 8 2.4. Data analysis ...................................................................................................................................... 8 3. Results............................................................................................................................................................9 3.1. +0.8 m AHD ................................................................................................................................... 11 3.2. +0.6 m AHD ................................................................................................................................... 11 3.3. +0.4 m AHD ................................................................................................................................... 11 3.4. +0.2 m AHD ................................................................................................................................... 11 3.5. 0 m AHD ......................................................................................................................................... 12 3.6. -0.5 m AHD..................................................................................................................................... 12 4. Discussion and management implications .............................................................................................14 4.1. Further Studies ................................................................................................................................16 5. References ...................................................................................................................................................17 6. Appendices..................................................................................................................................................22 List of Figures Figure 1: Map of Lakes Alexandrina and Albert, Murray Mouth and Coorong showing the location of vegetation monitoring sites in the Goolwa Channel and control sites in western Lake Alexandrina.....................................................................................................................................................7 List of Tables Table 1: List of vegetation monitoring sites (numbers relate to the map provided in Figure 1), site location (relative to Clayton Regulator) and the year sites were established. ...............................6 Table 2: Modified Braun-Blanquet (1932) scale estimating cover/abundance as per Heard and Channon (1997). ............................................................................................................................................8 Table 3: List of species and families recorded in Goolwa Channel (downstream of regulator) and western Lake Alexandrina (upstream of regulator) monitoring sites (* denotes exotic species). ...........................................................................................................................................................9 Gehrig and Nicol (2010) Vegetation Condition Monitoring in Goolwa Channel 2009-2010 Page ii ____________________________________________________________________________________________ Table 4: PERMANOVA Pseudo F-statistic results comparing location (Goolwa Channel and Lake Alexandrina) and season (spring 2009 and autumn 2010) for each elevation..........................13 List of Appendices Appendix 1: GPS coordinates (UTM format, map datum WGS84) for vegetation monitoring sites in Goolwa Channel and western Lake Alexandrina......................................................................22 Gehrig and Nicol (2010) Vegetation Condition Monitoring in Goolwa Channel 2009-2010 Page 1 ____________________________________________________________________________________________ Acknowledgements The authors would like to thank Arron Strawbridge, Rod Ward, Kate Mason and Pip Taylor for field assistance and Alec Rolston, Adrienne Frears, Rod Ward and Chris Bice for comments on early drafts of this report. This project was funded by the Department of Environment and Natural Resources, through the Murray Futures (Lower Lakes) Program and Murray Darling Basin Authority’s Living Murray Initiative through the South Australian Murray Darling Basin Natural Resources Management Board. Gehrig and Nicol (2010) Vegetation Condition Monitoring in Goolwa Channel 2009-2010 Page 2 ____________________________________________________________________________________________ Executive Summary Since 2007 water levels in Lakes Alexandrina and Albert have fallen to unprecedented lows exposing large areas of acid sulfate soils. In order to maintain higher water levels to manage acidification in Goolwa Channel and the lower reaches of the Finniss River and Currency Creek a regulator was constructed across Goolwa Channel, forming a weir pool between Goolwa Barrage and the township of Clayton. Water flowing from the Finniss River, Currency and Tookayerta Creeks is impounded by the regulator and prevented from flowing into Lake Alexandrina. In addition, water was pumped from Lake Alexandrina, to fill the weir pool to 0.7 m AHD in spring 2009 resulting in higher water levels in Goolwa Channel. This project aimed to assess changes through time and the impact of higher water levels, on the aquatic and littoral plant community in the Goolwa Weir Pool, surveys were conducted in spring 2009 and autumn 2010 at ten sites in Goolwa Channel, the lower Finniss River and lower Currency Creek and six sites in western Lake