ECD Lake Warden FINAL Sept 2009
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ECOLOGICAL CHARACTER DESCRIPTION OF THE LAKE WARDEN SYSTEM RAMSAR SITE, ESPERANCE, WESTERN AUSTRALIA A report by the Department of Environment and Conservation Ecological Character Description of the Lake Warden System Ramsar Site Acknowledgements Funding for the development of this document was sourced jointly from the Natural Heritage Trust (NHT) and the State and Commonwealth contributions to the National Action Plan for Salinity and Water Quality (NAP). NHT and NAP are jointly administered by the Australian Government departments of Agriculture, Fisheries and Forestry and the Environment, Water, Heritage and the Arts and the WA Natural Resource Management Office. In-kind contributions were gratefully received from the organisations represented on the Technical Advisory Group. Document Preparation This document has been prepared by the Wetlands Section of the Department of Environment and Conservation. Gareth Watkins - Author / conceptual models and graphics Jennifer Higbid - Internal review Technical Advisory Group Members Robyn Cail South Coast NRM David Cale DEC Sarah Comer DEC Ian Hartley Esperance Regional Forum Jennifer Higbid DEC Tegan Laslett DEC John Lizamore DEC Ken Read Esperance Bird Observers Group John Simons DAFWA Thank you to the following people for their contributions Nikki Cowcher DEC Henry Dabb South Coast NRM Greg Freebury DEC Paul Galloway DAFWA Photo credits Cover photograph: Mullet Lake, Esperance (J. Higbid) Internal photographs: G. Daniel, J. Higbid _________________________________________________________________________ I Ecological Character Description of the Lake Warden System Ramsar Site Other credits Symbols in conceptual models courtesy of the Integration and Application Network <http://ian.umces.edu/symbols/ >, University of Maryland Center for Environmental Science To reference this document Department of Environment and Conservation (2009). Ecological Character Description of the Lake Warden System Ramsar Site: A Report by the Department of Environment and Conservation . Prepared by G. Watkins, Department of Environment and Conservation, Perth, Western Australia. _________________________________________________________________________ II Ecological Character Description of the Lake Warden System Ramsar Site TABLE OF CONTENTS GLOSSARY ............................................................................................................X ABBREVIATIONS............................................................................................... XIV EXECUTIVE SUMMARY...................................................................................... XV 1.0 INTRODUCTION............................................................................................... 1 1.1 SITE DETAILS......................................................................................................... 2 1.2 PURPOSE OF AN ECOLOGICAL CHARACTER DESCRIPTION .......................... 3 1.2.1 OBJECTIVES OF THE LAKE WARDEN SYSTEM RAMSAR SITE ECOLOGICAL CHARACTER DESCRIPTION ............................................................................................... 5 1.3 RELEVANT TREATIES, LEGISLATION AND REGULATIONS .............................. 6 1.3.1 INTERNATIONAL AGREEMENTS/CONVENTIONS ..................................................... 6 1.3.2 NATIONAL LEGISLATION ........................................................................................... 7 1.3.3 WESTERN AUSTRALIA STATE LEGISLATION .......................................................... 8 2.0 DESCRIPTION OF THE LAKE WARDEN SYSTEM RAMSAR SITE............. 10 2.1 BACKGROUND..................................................................................................... 10 2.2 LAND TENURE AND LAND USE.......................................................................... 11 2.4 CLIMATE............................................................................................................... 13 2.5 WETLAND TYPES ................................................................................................ 16 2.6 RAMSAR CRITERIA ............................................................................................. 18 2.6.1 RAMSAR CRITERIA UNDER WHICH THE SITE WAS DESIGNATED ........................18 2.6.2 CURRENT RAMSAR CRITERIA .................................................................................20 2.6.2.1 ASSESSMENT AGAINST EACH OF THE RAMSAR CRITERIA FOR THE LAKE WARDEN SYSTEM RAMSAR SITE ....................................................................................................................23 3.0 LAKE WARDEN SYSTEM RAMSAR SITE: CRITICAL ECOSYSTEM COMPONENTS, PROCESSES, BENEFITS AND SERVICES............................. 27 3.1 CRITICAL ECOSYSTEM COMPONENTS AND PROCESSES ............................. 27 3.1.1 GEOMORPHOLOGY ...................................................................................................31 3.1.2 HYDROLOGY ..............................................................................................................32 3.1.2.1 HYDROLOGICAL SETTING .........................................................................................33 3.1.2.2 SURFACE AND GROUND WATER INTERACTIONS ...........................................................35 3.2.2.3 HYDROLOGICAL REGIME OF THE MAJOR LAKES WITHIN THE RAMSAR SITE .....................39 3.2.2.4 CATCHMENT TRENDS ...............................................................................................44 3.1.3 WATER QUALITY .......................................................................................................46 3.1.3.1 PHYSICO -CHEMICAL PROPERTIES OF THE MAJOR LAKES WITHIN THE RAMSAR SITE ........46 3.1.3.1.1 Salinity concentrations ................................................................................................. 46 3.1.3.1.2 pH ................................................................................................................................... 51 3.1.3.1.3 Nutrient concentrations ................................................................................................ 52 3.1.3.2 CATCHMENT SURFACE AND GROUNDWATER PHYSICO -CHEMICAL PROPERTIES ...............60 3.1.3.2.1 Salinity concentrations ................................................................................................. 60 3.1.3.2.2 pH ................................................................................................................................... 60 3.1.3.2.3 Nutrient concentrations ................................................................................................ 61 3.1.4 PHYSICAL PROCESSES ............................................................................................62 3.1.5 WETLAND SOILS .......................................................................................................62 3.1.6 BIOTA .........................................................................................................................66 3.1.6.1 WATERBIRDS ..........................................................................................................66 _________________________________________________________________________ III Ecological Character Description of the Lake Warden System Ramsar Site 3.1.6.1.1 Species diversity and abundance ............................................................................... 68 3.1.6.2 FISH ......................................................................................................................80 3.1.6.3 AQUATIC INVERTEBRATES ........................................................................................80 3.1.6.4 FLORA ...................................................................................................................85 3.1.6.4.1 Vegetation communities ............................................................................................... 85 3.1.6.4.2 Aquatic flora .................................................................................................................. 90 3.2 CRITICAL ECOSYSTEM BENEFITS AND SERVICES ......................................... 91 3.2.1 PROVISIONING SERVICES ........................................................................................95 3.2.2 REGULATING SERVICES ..........................................................................................95 3.2.3 CULTURAL SERVICES ...............................................................................................96 3.2.4 SUPPORTING SERVICES ..........................................................................................99 4.0 THREATS TO ECOLOGICAL CHARACTER ............................................... 101 4.1.1 ALTERED HYDROLOGY ..........................................................................................103 4.1.2 POLLUTION ..............................................................................................................106 4.1.3 ALTERED FIRE REGIMES ........................................................................................107 4.1.4 ACID SULFATE SOILS .............................................................................................108 4.1.5 OTHER THREATS ....................................................................................................109 4.2 NON-NATIVE AND ALIEN SPECIES .................................................................. 110 4.3 PLANT DISEASES.............................................................................................