Kakadu National Park
Ecological Character Description
List of Figures ii
List of Tables vi
List of Abbreviations xi
Executive Summary xiii
1 Introduction 1
1.1 Background 1
1.2 Scope and Purpose of this Study 2
1.3 Relevant Treaties, Legislation and Regulations 5
1.4 Key Terminology and Concepts 10
2 Description of the Site 16
2.1 Details of the Site- Summary 16
2.2 Location and Brief Description 16
2.3 Land Use and Tenure 21
2.4 Description of Wetland Types 23
2.5 Nomination Criteria Met by the Site 42
3 Critical Components, Processes and Services/Benefits 61
3.1 Study Approach 61
3.2 Overview of Critical Services, Components and Processes 63
3.3 Critical Components 66
3.4 Supporting Components 93
3.5 Critical Processes 96
3.6 Supporting Processes 104
3.7 Critical Services/Benefits 119
3.8 Supporting Services/Benefits 128
3.9 Conceptual Models 137
4 Limits of Acceptable Change 145
4.1 Background 145
4.2 Derivation of Limits of Acceptable Change 146
4.3 Summary of Limits of Acceptable Change 149
5 Overview of Current and Future Threats 158
5.1 Exotic Flora 159
5.2 Exotic Fauna 160
5.3 Climate Change 161
5.4 Tourism and Recreational Activities 162
5.5 Mining Activities 163
5.6 Public Safety and Crocodiles 163
5.7 Damage to Archaeological Resources and Rock Art 164
5.8 Living Resource Extraction 164
6 Changes to Ecological Character 165
6.1 Ecological Character Change Methods 165
7 Information Gaps, Monitoring and Education 177
7.1 Information Gaps 177
7.2 Monitoring Needs 179
7.3 Communication, Education, Participation and Awareness 180
8 References 182
9 Glossary 203
APPENDIX A:Project Committees 206
APPENDIX B:Detailed Methods 209
APPENDIX C:Fauna Species Lists 215
APPENDIX D:Endemic Species Distributions 232
APPENDIX E:Curriculum Vitae of Primary Authors 237
List of Figures
Figure 1 1 Key steps in preparing an Ecological Character Description (source: DEWHA 2008) 4
Figure 1 2 Generic conceptual model showing interactions between wetland ecosystem processes, components and services/benefits (source: DEWHA 2008) 13
Figure 1 3 Australian drainage divisions, indicating the Timor Sea Drainage Division (number VIII) (source: Bureau of Meteorology undated) 14
Figure 1 4 IMCRA provincial bioregions, indicating the Northern Provincial Bioregion (number 25) (source: Commonwealth of Australia 2006) 15
Figure 2 5 Location of the Kakadu National Park Ramsar site (denoted by red dashed l 18
Figure 2 6 Vegetation map for the Ramsar site (source: Tropical Savannas CRC undated) 26
Figure 2 7 Distribution of seagrass beds within and adjacent to the Ramsar site (source: Roelofs et al. 2005) 27
Figure 2 8 Seagrass species occurring within the Ramsar site (source: BMT WBM) 28
Figure 2 9 Smartline mapping of backshore habitats within the Ramsar site (source: GeoSciences Australia undated) 29
Figure 2 10 Estuarine waters of the South Alligator River (source: BMT WBM) 30
Figure 2 11 Intertidal marshes and saltpans along South Alligator River (source: BMT WBM) 31
Figure 2 12 Mangroves along the South Alligator River (source: BMT WBM) 32
Figure 2 13 Mangroves and Melaleuca forest extent within the Ramsar site (source: Parks Australia unpublished data) 33
Figure 2 14 Yellow Water – an example of a permanent lake and inland delta (source: BMT WBM) 34
Figure 2 15 Permanent river wetland type within South Alligator River (source: BMT WBM) 35
Figure 2 16 Seasonally inundated floodplain at Mamukala. (source: BMT WBM) 37
Figure 2 17 Melaleuca swamp forest at East Alligator River (source: BMT WBM) 38
Figure 2 18 Freshwater spring (source: Buck Salau, Parks Australia) 39
Figure 2 19 Billabongs within South Alligator River catchment (source: BMT WBM 2009) 40
Figure 2 20 Freshwater springs and monsoon forest within the Ramsar site (source: Parks Australia unpublished data) 40
Figure 2 21 (B) Catchment condition (C) estuary condition and (D) river condition at a bioregional scale. Red rectangle indicates location of the Kakadu Ramsar site. (source: NLWRA 2002) 47
Figure 3 22 Conceptual model showing interactions between critical and supporting components, processes and services/benefits within the Ramsar site 65
Figure 3 23 Area of mangroves mapped from 1950 to 1991 aerial photographs (source: Cobb et al. 2007) 69
Figure 3 24 Spatial extent of Melaleuca cover (green shading) on the Magela floodplain for four time periods (source: Staben 2008) 72
Figure 3 25 Generalised vegetation class changes on the Magela floodplain between 1983 and 2003 (source: Boyden et al. 2008) 74
Figure 3 26 Changes in non-hatchling densities of saltwater crocodiles for all four major rivers surveyed in Kakadu National Park – combined data (source: Britton 2009) 84
Figure 3 27 Changes in non-hatchling densities of saltwater crocodiles for Wildman River (WLDM), West Alligator River (WAR), South Alligator River (SAR) and East Alligator River (EAR) (source: Britton 2009) 85
Figure 3 28 Total freshwater crocodile sightings over time at each location (source: Kakadu National Park, unpublished data) 86
Figure 3 29 Yellow chat records for Kakadu National Park (source: Parks Australia unpublished and Armstrong 2004) 89
Figure 3 30 Map of know dry season distribution of pig-nosed turtle in the Ramsar site (source: Georges and Kennett 1989) 91
Figure 3 31 Changes in area of monsoon rainforest within Kakadu National Park (source: Banfai and Bowman 2006) 94
Figure 3 32 Monthly flow at three representative gauging stations in KNP (source: Australian Natural Resources Atlas website, data from 1958 to 1999) 98
Figure 3 33 Areas burnt per year for Kakadu National Park (a) and various landscape types (b to d) (source: Gill et al. 2000) 100
Figure 3 34 Mean (error bars = SD) and maximum number of nesting attempts per night, and numbers of nesting individuals per survey night recorded at Field Island (1990-2001) (source: Schäuble et al. 2006) 103
Figure 3 35 Mean maximum and minimum temperature at Jabiru Airport between 1971 and 2009. Upper and lower error bars denote the 90th and 10th percentiles (source: Bureau of Meteorology unpublished data) 105
Figure 3 36 Mean monthly rainfall and mean number of rain days at Jabiru Airport between 1971 and 2009. Upper and lower error bars denote the 90th and 10th percentiles (source: Bureau of Meteorology unpublished data) 105
Figure 3 37 Cusum plots (cumulative sum of mean deviations) of magpie goose numbers (white symbols) in the Northern Territory and Katherine River flow (black symbols) Figure reproduced from Bayliss et al. (2008) 106
Figure 3 38 Total number of tropical cyclones in the Northern Territory between 1963 and 2006 by category, where C5 is the most destructive category (source: Bureau of Meteorology) 107
Figure 3 39 Typical cross section of (top) upper estuary and (bottom) lower estuary 110
Figure 3 40 Water quality gauging stations in Kakadu National Park 114
Figure 3 41 Seasonal pattern of conductivity and nutrient concentrations (total nitrogen and ammonia) at gauging station G8210017 115
Figure 3 42 Groundwater within Kakadu National Park (source: Ticknell 2008) 117
Figure 3 43 Main reasons for visiting Kakadu National Park (source: Tremblay 2007) 129
Figure 3 44 Total international visitors numbers for Kakadu National Park (1998-2003 combined) (source: Morse et al. 2005) 130
Figure 3 45 Annual visitor numbers to Kakadu National Park in the 1980s (source: Commonwealth of Australia 1988) 131
Figure 3 46 Ramsar signage at Mamukala wetlands (source: BMT WBM) 133
Figure 3 47 Overview of wetland conceptual models 139
Figure 3 48 Shoreline and island conceptual model 141
Figure 3 49 River floodplains and billabongs (dry season) conceptual mode 142
Figure 3 50 River floodplains and billabongs (wet season) conceptual model 143
Figure 3 51 Upper catchment, escarpment and stone country conceptual model 144
List of Tables
Table 2 1 Site details and location description for the Kakadu National Park Ramsar site, both historically (pre-merger) and current (merged sites) 17
Table 2 2 Rivers and main streams within the site 21
Table 2 3 Coastal wetland types and representative examples within Kakadu National Park Ramsar site 24
Table 2 4 Inland wetland types and representative examples within Kakadu National Park Ramsar site 25
Table 2 5 Criteria for identifying Wetlands of International Importance as at listing, as documented in 1989 and 1995 RISs 42
Table 2 6 Summary of nomination criteria met by the two historic Kakadu National Park Ramsar sites as outlined in the 1998 RIS, and the current Kakadu National Park ECD 43
Table 2 7 Justification for criterion 1 48
Table 2 8 Threatened wetland-dependent species 50
Table 2 9 Ramsar nomination criterion 3 52
Table 3 10 Summary of critical and supporting components, processes and services/benefits 64
Table 3 11 Mangrove area and canopy height mapped from 1990 aerial photography (source: Mitchell et al. 2007) 67
Table 3 12 Number of Melaleuca trees on the Magela Floodplain (source: Riley and Lowry 2002) 71
Table 3 13 Mean abundance (number fish per 50 metres) of fish species from Mudginberri and Sandy billabongs for the period 1994 to 2005 (source: Humphrey et al. 2005) 81
Table 3 14 Saltwater crocodile densities prior to site listing in 1980 (Stage I) or 1989 (Stage II) (source: Britton 2009) 84
Table 3 15 Flow statistics for three representative gauging stations in KNP (source: Australian Natural Resources Atlas website, data from 1958 to 1999) 98
Table 3 16 Water quality data (80th percentiles; 20th and 80th percentiles for dissolved oxygen and pH) from gauging stations in the Kakadu National Park catchment and comparison to ANZECC guideline values. Values in red denote exceedance of guideline limits. (source: NRETAS unpublished data) 113
Table 3 17 Threatened wetland species that have critical habitats within the Ramsar site 121
Table 3 18 Key catchment, estuary and flow descriptors for each catchment within Kakadu National Park 123
Table 3 19 Native animal and plant species in the Aboriginal diet (source: Lucas and Russell-Smith 1993) 135
Table 4 20 Statistical measures describing LACs 148
Table 4 21 Critical components, processes and services/benefits, and relevant LAC indicators 150
Table 4 22 Limits of acceptable change (LAC) 151
Table 5 23 Summary of major threats to the Kakadu National Park Ramsar site 158
Table 5 24 Threat Consequence Categories 159
Table 5 25 Summary of Aerial Feral Animal Management Program 2008-2009 160
Table 6 26 A summary of ecological and management issues associated with feral fauna species. (after Bradshaw et al. 2007) 170
Table 6 27 Assessment of ecological character changes against LAC 174
Table 7 28 Summary of information/knowledge gaps 177
This report was prepared by BMT WBM Pty Ltd with expert input from Austecology Pty Ltd and Melaleuca Enterprises under contract to the Department of Sustainability, Environment, Water, Population and Communities.
The consultant project team wish to express their thanks to the members of the Inter-Governmental Steering Group and Knowledge Management Committee formed for the project for their assistance and guidance.
Photos that appear in the report are supplied by BMT WBM or other organisations where noted. Figures that have been reproduced (without modification) from other sources have been referenced accordingly.
Disclaimer: In undertaking this work the authors have made every effort to ensure the accuracy of the information used. Any conclusions drawn or recommendations made in the report are done in good faith and BMT WBM take no responsibility for how this information and report are used subsequently by others.
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 Australian Government 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 EPBC Act, 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.
Use of terms and information sources: All definitions and terms used in this draft report were correct at the time of production in June 2010. Refer to the References (Section 8) for works cited and Glossary (Section 8) for a list of key terms and terminology used.
Citation: This report can be cited as follows:
BMT WBM (2010) Ecological Character Description for Kakadu National Park Ramsar Site. Prepared for the Australian Government Department of Sustainability, Environment, Water, Population and Communities.
List of Abbreviations
Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand
Alligator Rivers Region Technical Committee
Alligator Rivers Region
Brucellosis and Tuberculosis Eradication Campaign
China-Australia Migratory Bird Agreement
Charles Darwin University
Communication, education, participation and awareness
Convention on the Conservation of Migratory Species
Catch Per Unit Effort
Cooperative Research Centre (for Tropical Savannas Management)
Commonwealth Scientific and Industrial Research Organisation
Department of Sustainability, Environment, Water, Population and Communities
Ecological Character Description
Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and regulations under that Act
Environmental Research Institute of the Supervising Scientist
Highest Astronomical Tide
Integrated Marine and Coastal Regionalisation of Australia
International Union for Conservation of Nature
Japan-Australia Migratory Bird Agreement
Knowledge Management Committee
Key Result Area
Kakadu Research Advisory Committee
Limit(s) of Acceptable Change
Millennium Ecosystem Assessment
Lowest Astronomical Tide
(matter of) National Environmental Significance
Northern Land Council
Natural Resource Management
Northern Territory Department of Natural Resources, Environment, the Arts and Sport (previously NRETA)
Office of the Supervising Scientist
Ramsar Information Sheet
Republic of Korea- Australia Migratory Bird Agreement
Tropical Rivers and Coastal Knowledge
Threatened Species Scientific Committee
The Kakadu National Park Ramsar site is listed as a Wetland of International Importance under the “Convention on Wetlands of International Importance especially as Waterfowl Habitat” or, as it is more commonly referred to, the Ramsar Convention (the Convention).
This report provides the Ecological Character Description (ECD) for the Kakadu National Park Ramsar site, and has been prepared in accordance with the National Framework and Guidance for Describing the Ecological Character of Australia’s Ramsar Wetlands (DEWHA 2008). This is the first ECD prepared for the site. In parallel with the preparation of the ECD, the Ramsar Information Sheet (RIS) for the site has been updated for submission to the Australian Government and Ramsar Secretariat.
The Kakadu National Park Ramsar site is located approximately 200 kilometres east of Darwin in the Northern Territory. The Kakadu National Park Ramsar site was historically two separate Ramsar sites within Kakadu National Park. These were Kakadu National Park (Stage I including wetland components of Stage III) and Kakadu National Park (Stage II). Kakadu National Park Stage I was originally listed as a Ramsar site in 1980 and expanded in 1995 to include wetland components of Stage III, while Stage II was listed in 1989 as a separate Ramsar site. The separate listing under the Stages reflected the historical listing of the area as a World Heritage site and a national park.
The Kakadu National Park (Stage I including wetland components of Stage III) Ramsar site comprised of all lands and waters in the eastern portion of the Kakadu National Park, following the eastern boundary of the Park along the East Alligator River and including the Nourlangie, Jim Jim and Barramundi Creeks. In 1995, the boundaries of site number two were extended to include only the wetland habitats within the eastern and southern areas of Kakadu National Park (Stage III).
Kakadu National Park (Stage II) Ramsar site encompassed all lands and waters situated in the northern and western part of the National Park, including the Wildman, West Alligator and South Alligator River systems and their floodplains, following the western Kakadu National Park boundary. The Stage II area also included both Field Island and Barron Island within Van Diemen Gulf to the low water mark.
In April 2010, the two Ramsar sites were merged together to form a single Ramsar site, called Kakadu National Park. In addition, the site was extended by approximately 600 000 hectares to include all remaining areas of Stage III. The merger and extension bought the Ramsar boundary in line with the existing boundary of the national park.
Ecological Character Descriptions describe the ecological character of a wetland at the time of its listing as a Wetland of International Importance. Although Kakadu National Park is now a single Ramsar site, it is important to report baseline data that reflects the different listing dates of the three Stages.
The Ramsar site is bounded by the following geographic features:
Van Diemen Gulf and the Timor Sea in the north
the East Alligator River and Arnhem Land in the east
Wildman and Mary River catchments in the west, and
Arnhem Land plateau to the south.
Approximately 50 percent of Kakadu National Park is Aboriginal land under the Aboriginal Land Rights (Northern Territory) Act 1976. Most of the remaining area of land is under claim by Aboriginal people. Title to Aboriginal land in the Park is held by Aboriginal Land Trusts that have leased their land to the Director of National Parks (under the Environment Protection and Biodiversity Conservation Act 1999) for the purpose of being managed as a Commonwealth Reserve. Land in the Park that is not Aboriginal land is vested in the Director.
The Kakadu National Park Ramsar site is composed of a diversity of coastal and inland wetland types. Wetland types present range from intertidal forested wetlands and mudflats, to seasonal freshwater marshes and permanent freshwater pools. Using the Ramsar typology, there are five coastal types and eight inland types within the Stage I and Stage III area. Within the Stage II area, there are nine coastal types and seven inland types.
The ECD has reviewed the Ramsar Nomination Criteria under which the two original Ramsar sites were listed as Wetlands of International Importance, and examined the applicability of the revised and new Criteria under the Convention that have been added since the sites were originally listed in 1980 and 1989. In this context, Kakadu National Park is now seen as meeting all nine Nomination Criteria of the Convention, recognising the representative wetland habitats of the site at a bioregional level, support of populations of vulnerable wetland species, its characteristics as a centre of endemism and high biodiversity including its diversity of habitats, support for key life-cycle functions such as waterbird breeding and refugia values, its importance for supporting substantial populations of waterbirds and fish diversity and fish nursery and spawning habitats and its support of at least one percent of the national population of several non-avian wetland species.
Critical components of the Ramsar site include key wetland habitats and populations of waterbirds, freshwater fish, aquatic invertebrates, turtle and crocodiles. The critical ecosystem processes that underpin the habitats of the Kakadu National Park Ramsar site include hydrology, fire regimes and notable biological processes, with supporting processes including climate, tidal hydraulics, groundwater, water quality, geology and geomorphology.
The wetland components and processes of the site support a broad range of ecosystem services/benefits including support of threatened fauna, support of endemic species, fisheries resource values and contemporary living culture. Additionally, cultural and socio-economic services are equally diverse, noting the particular importance of the wetlands of the site to the traditional owners and caretakers of Kakadu National Park (the ‘Bininj’), as well as tourism and recreational values.
A summary of the critical services/benefits provided by the Kakadu National Park Ramsar site and the underlying critical ecosystem components and processes nominated by this ECD is given in Table E-1. The critical wetland services/benefits nominated were based on the attributes of the site described in the Ramsar Nomination Criteria as well as identifying critical ‘cultural’ services/benefits provided by the site in terms of human use. The critical wetland components and processes have been selected based on the particular characteristics of Kakadu National Park and on the basis that they underpin the critical services/benefits, but may also be critical in their own right.
As required by the National Framework document, the study has:
sought to define the natural variability and limits of acceptable change (LACs) for the critical components, processes and services/benefits identified
examined ecological character changes that have been observed or documented since listing of the sites in 1980 and 1989 (including assessment against relevant LACs), and
investigated current and future threats to ecological character.
While the level of quantitative information and data needed to provide a more definitive assessment of ecological character change (and to set more definitive LACs as sought by the National Framework) are not available, it would appear unlikely that any of the LACs presented in the ECD have been meaningfully exceeded. It is noted however that saltwater intrusion processes have possibly degraded freshwater billabongs and other palustrine wetlands and Melaleuca communities.
The effect of saltwater intrusion in the floodplain areas of the Park has had the effect of changing the spatial characteristics and distribution of tidal creeks and associated mangrove environments over a long time period, often at the expense of predominantly freshwater systems. This includes the loss of several freshwater billabong environments located proximal to the tidal channels and at the fresh-salt interface areas of the major river systems, noting that these features have both ecological and cultural significance in terms of traditional food sources and traditional customary usage. However, the extent to which saltwater intrusion represents an ecological character change is difficult to assess noting that saltwater intrusion into Kakadu National Park’s freshwater wetlands is a continuous natural process. A key factor to be considered is whether the environmental change or the rate of change can be perceived as having an anthropogenic source.
Recent or continuing threats that are notable in the context of the site that may affect future ecological character include:
introduction and/or proliferation of exotic flora and fauna
tourism and recreational activities (including boating)
damage to archaeological resources and rock art, and
living resource extraction.
Of these threats, future impacts from climate change in terms of increased saltwater intrusion and impacts from the continuing persistence and spread of cane toads are seen as the most likely and potentially severe.
Information gaps, monitoring needs and recommendations in relation to communication, education, participation and awareness messages are also identified in the ECD. Key information gaps in the context of this ECD require:
additional research and monitoring to establish an ecological character baseline for the key habitats
better information and data sets about the presence and natural history of critical wetland species and their habitats including for example, surveys of threatened plant species, aquatic fauna species such as the river shark species and more systematic surveys of important avifauna and fish species and populations
better information and understanding about the natural variability of wetland fauna populations and key attributes and controls on those populations
additional investigation of the ecological character thresholds of particular habitats and communities to changes in key attributes/controls such as hydrology. The LACs stated in the ECD should be reviewed and revised as improved information becomes available, and
more specific assessment of the vulnerability of the site to the impacts of climate change, and adaptation options that could be explored to reduce the future impacts.
In accordance with the above, monitoring needs and recommendations presented in this ECD relate broadly to obtaining data to assess future changes to ecological character as defined by the critical components, processes and services/benefits associated LACs for the site. Since the monitoring needs are quite extensive, a broad scale ecosystem health-based monitoring program may be most appropriate for the Ramsar site using lessons learned from similar approaches elsewhere. Emphasis should be placed on the collection of data and information about critical and supporting process indicators, such as water quality and biotic indicators of ecosystem health.
A combined set of communication, education, participation and awareness messages relevant to the ECD have been presented and can be used to communicate the importance of the site, why it was listed, possible changes to ecological character, the threats to the site and future actions required. These messages also serve as a summary of the key findings and conclusions of the ECD study.