Edith Cowan University Research Online Theses : Honours Theses 2002 The fringing halophytic vegetation of Lake Austin: A study of mining impacts and vegetation dynamics Simone Vellekoop Edith Cowan University Follow this and additional works at: https://ro.ecu.edu.au/theses_hons Part of the Environmental Monitoring Commons, and the Horticulture Commons Recommended Citation Vellekoop, S. (2002). The fringing halophytic vegetation of Lake Austin: A study of mining impacts and vegetation dynamics. https://ro.ecu.edu.au/theses_hons/580 This Thesis is posted at Research Online. https://ro.ecu.edu.au/theses_hons/580 Edith Cowan University Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorize you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. 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Aanstillil: a sttlllldy of mnl!llnllilg ii.mpacts and vegetatnon dynamics By Simone Vellekoop This thesis is submitted in partial fulfillment of the requirements for the award of Honours in the Bachelor of Science (Environmental Management) at the School of Natural Sciences, Faculty of Communication, Health ::.nd Sciences, Edith :::_·owan University. Date of Submission: 29 November 2002 USE OF THESIS The Use of Thesis statement is not included in this version of the thesis. ABSTRACT Mining operations in arid regions of Western Australia are faced with many environmental management issu;'!s. One such issue ~ the disposal of mine water to the environment. Mine water is commonly discharged to nearby salt lakes under licence by the Department of Environmental Protection. Licence conditions dictate that the dischar~e water and the receiving environment be monitored to allow impacts on the environment to be detected. Salt lakes are associated with vegetation communities dominated by halophytic members of the Chenopodiaceae, While these plants are tolerant of salinity extremes, the germination stage of many species requires periods of lowered salinity. There is therefore potential for the recruitment stage of these vegetation communities to be affected by the discharge of hypersaline mine water. At Lake Austin, Big Bell Gold Operations discharge hypersaline mine water to this saline wetland system. This study has investigated whether this discharge has had an impact on the fringing vegetation of the lake. Secondly, the vegetation dynamics of the fringing vegetation have been investigated during a flood/drought cycle between 1998 and 2002 with the aim of increasing our understanding of these communities. Using an existing monitoring program established by the Centre for Ecosystem Management (CEM) in 1998, as well as twenty additional sites surveyed in 2002, soil and vegetation parameters were measured and assessed to test for evidence of an impact from the discharge of hypersaline mine water. A glasshouse experiment inundated soil samples from discharge and non-discharge zones with water of varying salinity to test for difference in seed germination between treatments and between zones. Halosarcia fimbriata, H. halocnemoides {form a), and H. pruinosa (form a) were dominant in the communities found at Lake Austin. Very few significant differences ii were found in changes of soil and vegetation parameters between location (discharge versus non-discharge sites) and/or time (1998, 2000 and 2002). The discharge water is linked to changes in soil pH and possibly soil salinity, however, there appears to be no impact on the vegetation. A number of explanations are given as to why an impact on the vegetation was not detected, including a lack of statistical power. The vegetation dynamics are described in relation to the flood/drought cycle experienced between 1998 and 2002. There are links between seed germination, seedling growth and subsequent structure of the Halosarcia fimbriata community and flooding frequency, depth and duration. There are three main management implications that have arisen from this study. Firstly, the samplinf; effort needs to be increased in order to be confident that significant differen<Y.;s will be detected, if indeed there are any. Secondly, further investigation of the vegetation dynamics is required to enhance impact mitigation and minimisation strategies. Finally, an engineering solution is suggested to prevent discharge wa·,er from coming into contact with fringing vegetation. iii DECLARATION I certify that this thesis does not incorporate without acknowledgment any material previously submitted for a degree or diploma in any institution of higher education; and that to the best of my knowledge and belief it does not contain any material previously published or written by another person except where reference is made in the text. Signed: L I Date: 20 /)cc~/1'1~ ~3 ,· iv ACKNOWLEDGMENTS 1 would like to thank my supervisor Dr Eddie van Etten for doing a great job, providing me with the support and guidance I was looking for. I have been waiting for an opportunity to be guided in learning. Thank you. I would like to acknowledge the assistance and in-kind support of Harmony Big Bell Gold operations, in particular Jo Ward and Mark Hewitt. Thanks for your friendly help on site, and for answering the numerous phone calls and emails. Thanks arc also due to the people who have held me up over the past year: Thanks Mum for everything; Dad and Sui for breakfasts on Sunday; Jo, Fee and Mike for those Thursday night "management plan" meetings, and Jo -thanks for s\eepies, swimmies and drinkies, and motivating me at the end of a long day with Bell> and Bo-Bo; thanks Tamun for setting many standards to aspire to; Kirsty, Ruth, Olivia and Pat for sharing our mutual stress; Gary, you are a guru; and thanks to Clay, Brad, Jody, John and Simon who were always available to help solve a problem or three. To Prita and Davey, you two are gold. To Bo Schmitt, thanks for taking care of us. I dedicate this thesis to you. v TABLE OF CONTENTS ABSTRACf ................................................................................................................................................ 11 DECL<\RATION ................................................................................................................ ,...................... IV ACKNOWLEDGMENTS ............................................................................. ,........................................... V TABLE OF CONTENTS ..........................................................................................................................VI LIST OF FIGURES ............................................................................................................................... VIII LIST OF TABLES ..................................................................................................................................... X CHAPTER 1 -INTRODUCTION ............................................................................................................ 1 1.1 BACKGROUND ...................... , ......................... ,., .................................................................................. l 1.1.1 Mining in arid climate areas ofAustralia .................................................................................. 1 1.1.2 Mine dewatr!ril:g ......................................................................................................................... 2 1.1.3 Dewateritlg to sa1tlake~· ............................................................................................................. 3 1.1.4 Licensing by the DEP ................................................................................................................. 4 1.1.5 Big Bell Gold Operations ........................................................................................................... 4 1.1.6 Salt lakes ..................................................................................................................................... 5 1.1. 7 The jringi11g vegetlllion ............................................................................................................... 6 1.2 RATIONALE ......................................................................................................................................... 7 1.3 AlMS AND OBJECfiVES ....................................................................................................................... 8 1.4 TIIES\S STRllCfURE ............................................................................................................................. 8