Ecological Character Description for the Forrestdale and Thomsons Lakes Ramsar Site
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Ecological Character Description for the Forrestdale and Thomsons Lakes Ramsar Site A report to the Department of Environment and Conservation Kellie Maher and Jennifer Davis Murdoch University June 2009 Aquatic Ecosystems Research Murdo ch Un iversity Acknowledgements Funding for the development of this document was provided by the Department of the Environment, Water, Heritage and the Arts (Australia) and the Department of Environment and Conservation (Western Australia). People and organisations involved in contributing to the ecological character description (particularly in providing baseline data) include: Michael Coote, Department of Environment and Conservation Sonny Vitale, Department of Water Mike Bamford, Bamford Consulting Wes Bancroft, Bamford Consulting Andrew Silcocks, Birds Australia Adrian Pinder, Department of Environment and Conservation Tanya Brown, Department of Water Kitty Cunningham, Department of Water Joe Miotti, Water Corporation Jacquie Bellhouse, Water Corporation Tim Jenkins, Water Corporation Thanks to Robyn Pickering, Philip Jennings and Rod Giblett for their comments on a draft of this report. The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for Sustainability, Environment, Water, Population and Communities or the Administrative Authority for Ramsar in Australia. While reasonable efforts have been made to ensure the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. Guidance on the development of Ecological Character Descriptions, including Limits of Acceptable change, are areas of active policy development. Accordingly there may be differences in the type of information contained in this Ecological Character Description, to those of other Ramsar wetlands. This information does not create a policy position to be applied in statutory decision making. Further it does not provide assessment of any particular action within the meaning of the Environment Protection and Biodiversity Conservation Act 1999, nor replace the role of the Minister or his delegate in making an informed decision on any action. This report is not a substitute for professional advice rather it is intended to inform professional opinion by providing the authors' assessment of available evidence on change in ecological character. This information is provided without prejudice to any final decision by the Administrative Authority for Ramsar in Australia on change in ecological character in accordance with the requirements of Article 3.2 of the Ramsar Convention. Users should obtain any appropriate professional advice relevant to their particular circumstances. Black-winged Stilts in flight over Thomsons Lake, 28th June 2008, during a deep-water phase (Figure E1) (J. Davis). Cover photo: Black Swans at Thomsons Lake, 28th June 2008, during a deep-water phase (Figure E1) (J. Davis). ii Table of Contents List of Tables............................................................................................... vi List of Figures ............................................................................................ vii Glossary ....................................................................................................... xi List of Abbreviations ................................................................................ xiv Executive Summary .................................................................................... 1 1. Introduction ........................................................................................... 8 1.1 Site details ........................................................................................................... 8 1.2 Purpose of Ecological Character Descriptions .................................................... 9 1.3 Objectives of the Forrestdale and Thomsons Lakes Ecological Character Description ........................................................................................................ 12 1.4 Legislative Framework ...................................................................................... 13 1.4.1 International Treaties/Agreements ............................................................. 13 1.4.2 National Legislation and Policy ................................................................. 13 1.4.3 Western Australia State Legislation and Policy ......................................... 14 1.5 Methodology ...................................................................................................... 16 2. Description of Forrestdale and Thomsons Lakes ............................ 17 2.1 Site location ....................................................................................................... 17 2.2 Climate .............................................................................................................. 19 2.3 Land tenure ........................................................................................................ 25 2.4 Ramsar Criteria .................................................................................................. 28 2.4.1 Criteria under which the site was designated (1990) .................................. 28 2.4.2 Ramsar Criteria currently met .................................................................... 28 2.4.3 Ramsar Criteria no longer met.................................................................... 29 2.5 Wetland types .................................................................................................... 31 3. Ecosystem components, processes, benefits and services ................ 31 3.1 Geomorphology and Geology ........................................................................... 32 3.2 Hydrology .......................................................................................................... 32 3.3 Physico-chemistry ............................................................................................. 46 3.4 Fauna ................................................................................................................. 53 3.4.1 Mammals .................................................................................................... 53 iii 3.4.2 Reptiles and Amphibians ............................................................................ 53 3.4.3 Aquatic Invertebrates .................................................................................. 54 3.4.4 Terrestrial birds........................................................................................... 58 3.4.5 Waterbirds .................................................................................................. 58 3.5 Vegetation .......................................................................................................... 72 3.6 Wetland processes and ecological regime ......................................................... 74 3.7 Ecosystem benefits and services........................................................................ 75 3.7.1 Indigenous heritage..................................................................................... 75 3.7.2 Non-indigenous heritage............................................................................. 77 3.7.3 Aesthetic, recreation, science and education values ................................... 78 4. Conceptual models .............................................................................. 79 4.1 Annual deep-water and shallow-water phases................................................... 79 4.2 Drivers and effects of ecological change ........................................................... 81 4.3 Wetland response to altered water regime ......................................................... 82 5. Limits of acceptable change ............................................................... 85 6. Threats .................................................................................................. 91 7. Changes to ecological character ......................................................... 96 7.1 Hydrology .......................................................................................................... 96 7.2 Physico-chemistry ............................................................................................. 97 7.3 Invertebrates ...................................................................................................... 98 7.4 Waterbirds ......................................................................................................... 98 7.5 Aquatic plants .................................................................................................... 99 7.6 Littoral vegetation.............................................................................................. 99 7.7 Wetland processes and ecological regime ....................................................... 100 7.8 Ramsar Criteria ................................................................................................ 100 7.8.1 Ramsar Criteria currently met .................................................................. 100 7.8.2 Ramsar Criteria no longer met.................................................................. 100 8. Knowledge gaps ................................................................................