NORTHERN AGRICULTURAL DISTRICTS OF SOUTH AUSTRALIA
An assessment of selected inland wetlands of the Northern Agricultural Districts.
South Australia. Department for Environment and Heritage, South Australia.
Author Russell Seaman
Scientific Officer, Wetlands Management.
National Parks and Wildlife SA Cartography and design
Russell Seaman Photographs Russell Seaman
Geographical Information System Data
Supplied by Geographical Analysis and Research Unit, Planning SA, Department for Transport, Urban Planning and the Arts.
and
The Department for Environment and Heritage, South Australia.
Funding Sources Environment Australia Support Organisation National Parks and Wildlife SA
Acknowledgments
In the preparation of this report the expertise, advice and support of several people is greatly appreciated.
• Rob Walsh
• Roman Urban, DEH.
• Sandy Carruthers, Planning SA.
• Tim Croft, DEH.
• Andrew Graham
Executive Summary
The Wetland Inventory for the Northern Agricultural Districts documents a representative sample of inland wetlands by recording their physical, chemical and biological attributes.
Twenty-nine wetlands were surveyed during November 2000; the majority of these wetlands included saline lake systems and brackish water bodies. Nelshaby Reserve (north-east of Port Pirie) is classified as the only freshwater wetland surveyed.
The aquatic invertebrate fauna was notably scarce in many of the wetlands surveyed, and this is attributed to the high conductivity readings in the majority of wetlands. However, nine wetlands displayed good invertebrate trophic levels. The correlation between increasing salinity levels and decreasing biological activity was clear; this decline is of concern for the health of many wetlands.
A number of wetlands surveyed are considered to be nationally important as they meet the ANZECC criteria of being a good example of a wetland type occurring within a biogeographic region in Australia. These wetlands include the saline lake systems within Innes National Park. Three wetlands are recommended for monitoring, these include Gum Flat adjacent to Minlaton, Native Hen Lagoon (south of Yorketown) and Chain of Lakes (Innes National Park).
SECTION ONE - WETLAND INVENTORY... 7
1.0 INTRODUCTION ... 7
2.0 REPORT STRUCTURE... 7
3.0 PROJECT SCOPE ... 7
4.0 OVERVIEW OF PAST WETLAND INVENTORY STUDIES ... 8
5.0 WETLAND RISK ASSESSMENT ... 9
6.0 WETLAND INVENTORY METHODOLOGY ... 10
6.1 STUDY AREA BOUNDARIES... 10
6.2 SITE SELECTION... 10
6.3 GIS DATABASE... 10
7.0 WETLAND INVENTORY SURVEY ... 11
7.1 WETLAND SURVEY TEMPLATE... 11
SECTION TWO - WETLAND ASSESSMENT ... 12
8.0 INTRODUCTION ... 12
8.1 WETLAND OVERVIEW... 12
9.0 WETLAND LAND USE ... 13
9.1 BACKGROUND... 13
9.2 ANALYSIS... 13
10.0 MANAGEMENT AUTHORITY... 14
10.1 BACKGROUND... 14
10.2 ANALYSIS... 14
11.0 ENVIRONMENTAL ASSOCIATIONS AND IBRA REGIONS ... 15
11.1 BACKGROUND... 15
11.2 ANALYSIS... 15
12.0 WETLAND AREA... 16
12.1 BACKGROUND... 16
12.2 ANALYSIS... 16
13.0 LANDFORM ELEMENT ... 17
13.1 BACKGROUND... 17
13.2 ANALYSIS... 17
14.0 GEOLOGY... 18
14.1 BACKGROUND... 18
14.1 ANALYSIS... 18
15.0 HYDROLOGY... 19
16.0 FLORA ANALYSIS ... 19
17.0 DEGRADATION AND DISTURBANCE ... 22
17.1 BACKGROUND... 22
17.2 ANALYSIS... 22
19.0 AQUATIC FAUNA ANALYSIS... 24
19.1 INVERTEBRATES... 24
19.1.1 Ecological benefits ... 24
19.1.2 Trophic dynamics... 24
19.2 SALINE SYSTEMS... 25
19.3 ANALYSIS... 25
19.3.1 Frequency of invertebrate occurrence ... 26
19.3.2 Trophic levels... 27
19.3.3 Invertebrate records for each surveyed site ... 28
20.0 AVI-FAUNA ... 29
21.0 WATER CHEMISTRY ... 30
21.1 PH... 31
21.1.1 Background... 31
21.1.2 Analysis... 32
21.2 CONDUCTIVITY... 32
21.2.1 Background... 32
21.1.2 Analysis... 33
21.3 TURBIDITY... 34
21.3.1 Background... 34
21.3.2 Analysis... 36
21.4 WATER TEMPERATURE... 37
21.4.1 Background... 37
21.4.1 Analysis... 37
22.0 RAPID ASSESSMENT... 38
22.1 AQUATIC FAUNA... 38
22.2 AQUATIC FLORA... 38
22.3 RIPARIAN VEGETATION RAPID ASSESSMENT... 38
22.3.1 Analysis... 39
23.0 WETLAND CONDITION SCORE... 40
24.0 RAPID ASSESSMENT TOTAL SCORE ... 40
25.0 ANZECC WETLAND CRITERIA... 41
25.1 ANALYSIS... 41
26.0 WETLAND TYPES ... 42
26.1 Analysis... 43
SECTION THREE - WETLAND MONITORING... 44
27.0 INTRODUCTION ... 44
27.1 Ecological change... 44
28.0 MONITORING PROTOCOLS AND INDICATORS ... 46
28.1 EARLY WARNING INDICATORS... 47
28.2 TOXICITY TESTS... 47
28.3 FIELD EARLY WARNING INDICATORS... 48
28.4 RAPID ASSESSMENTS... 48
29.0 RECOMMENDED INDICATORS FOR MONITORING SURVEYED WETLANDS... 48
29.1 EARLY WARNING INDICATORS – WATER CHEMISTRY... 48
29.2 ECOSYSTEM BASED INDICATOR... 49
29.3 OTHER CONSIDERATIONS... 49
BIBLIOGRAPHY ... 53
APPENDIX 1 WETLAND INVENTORY DESCRIPTIONS... 57
APPENDIX 2 INVERTEBRATE RECORDS FOR SURVEYED WETLANDS... 68
Figures FIGURE 9-1. ON SITE WETLAND LAND USES... 13
FIGURE 10-1. TENURE AND MANAGEMENT... 14
FIGURE 12-1. WETLAND AREA. ... 16
FIGURE 18-1. AQUATIC VEGETATION TYPES... 23
FIGURE 19-1. INVERTEBRATE SCORES. ... 27
FIGURE 21-1. TEMPORARY WETLAND CYCLES... 30
FIGURE 21-2. PH VALUES... 31
FIGURE 21-3. FISH ACTIVITY AGAINST TURBIDITY VALUES AND TIME... 35
FIGURE 26-1. WETLAND TYPES OF SURVEYED WETLANDS WITHIN THE NAD... 43
Plates PLATE 1. LAKE BUMBUNGA... 16
PLATE 2. INNESTON LAKE, INNES NATIONAL PARK... 17
PLATE 3. TEA-TREE SWAMP... 20
PLATE 4. GUM FLAT... 20
PLATE 5. NELSHABY RESERVE. ... 22
PLATE 6. NELSHABY RESERVE. ... 33
PLATE 7. SNOWTOWN GOLF LAKE. ... 36
PLATE 8. CHAIN OF LAKES. ... 39
PLATE 9. DIAMOND LAKE. ... 39
PLATE 10. TEA TREE SWAMP. ... 43
PLATE 11. GUM FLAT... 51
PLATE 12. NATIVE HEN LAGOON. ... 51
PLATE 13. CHAIN OF LAKES. ... 51 Maps
Map 1. Study boundaries
Map 2. Wetland Survey Locations Map 3. Environmental Associations
SECTION ONE WETLAND INVENTORY 1.0 INTRODUCTION
This Wetland Inventory for the Northern Agricultural Districts (NAD) documents a
representative sample of inland wetlands and records their physical, chemical and biological attributes. From this information, aquatic environments that contain high biodiversity are highlighted, and threats are documented. The inventory provides a snap shot of the condition and conservation value of wetlands throughout the Northern Agricultural Districts. Those wetlands that meet one or more of the Australian and New Zealand Environment and Conservation Council (ANZECC) criteria for an important wetland will be nominated for inclusion in the National Directory of Important Wetlands in Australia.
The Wetland Inventory for the Northern Agricultural Districts is an initiative of the Wetland Section-Environment Australia and the South Australian Department for Environment and Heritage.
2.0 REPORT STRUCTURE
This report is divided into three sections, namely the wetland inventory, wetland assessment and wetland monitoring.
Section 1 - Wetland Inventory. Outlines the project aims and inventory methodology.
Section 2 - Wetland Assessment. Provides an analysis of the wetland inventory, which includes the identification of wetland values and threats.
Section 3 – Wetland Monitoring. Discusses frameworks for monitoring, and recommends indicator species for monitoring and specific wetlands to monitor.
3.0 PROJECT SCOPE
The project scope consist of five actions, these are to:
1. To undertake baseline wetland surveys for inland surface waters within the NAD.
2. Identify wetlands of conservation significance, according to agreed ANZECC classification.
3. Provide digital coverage of spatial boundaries of identified wetlands in ARC/INFO compatible format at appropriate scale, in consultation with Planning SA.
4. Produce a report detailing the physical, biological and chemical attributes of wetlands within the NAD.
5. Nominate wetlands of significance for inclusion in the Directory of Important Wetlands in Australia.
4.0 OVERVIEW OF PAST WETLAND INVENTORY STUDIES
The most comprehensive listing of wetlands in South Australia in terms of numbers and coverage is by Lloyd and Balla (1986). This study identified approximately 1500 wetlands and complexes state-wide.
The Lloyd and Balla listing was a desktop study that collated and recorded information within a standard format. This included:
• wetland type • aquatic and fringing vegetation
• name • wetland condition
• location • water regime
• size • landuse
• catchment • impacts
• aquatic fauna • tenure.
The Lloyd and Balla report provides a good starting point in understanding the extent and some attributes of South Australian wetlands. However, the study falls short in providing up to date information on invertebrate composition, water chemistry and basic landform
information. Thirty-six wetlands are documented for Yorke Peninsula and thirty-eight wetlands for the mid north/Flinders Ranges regions.
Since Lloyd and Balla’s 1986 report, several state-wide studies have mirrored this kind of information collection and presentation, but have generally not collected detailed field baseline wetland information. None-the-less, good information has been generated for certain areas including the Murray River corridor, for example, Thompson’s (1986) study documented, mapped and described the River Murray Wetlands and Jensen et al (1996) Wetland Atlas report of the South Australian Murray Valley Wetlands made inroads into spatially capturing the locations through the use of GIS. The introduction of linking wetlands with GIS enabled the creation of a wetlands GIS database for the Murray Valley Wetlands. In 1997 Carruthers and Hille developed a GIS database for the South East wetlands. This database recorded wetland type, name, complex, watercourses and assigned a condition score and conservation value. The benefits of collecting data and linking it to GIS became evident not only for environmental planning and for information retrieval, but also for reporting to Environment Australia on the extent of wetland resources.
In 1993 the Australian Nature and Conservation Agency published the first edition of ‘A Directory of Important Wetlands in Australia’. A second edition was complied in 1996, which included information on 68 wetlands South Australia. Four coastal wetlands are listed within the NAD (Point Davenport, Wills Creek, Clinton and the Upper Spencer Gulf).
De Jong and Morelli (1996) commented that in compiling the Directory of Important Wetlands it became apparent that several regions within South Australia were lacking baseline wetland information. They suggested that there is a need for systematic inventories, biological
surveys and research programs in many areas of the State. Wetland information in regions such as the Great Victoria Desert, Flinders and Olary Ranges, Eyre Peninsula, Yorke Peninsula, Kangaroo Island and Nullarbor are quite inadequate.
The Wetland Inventory for the NAD combines several of these recommendations, including continuing the development of a GIS database and providing baseline information which includes physical, chemical and biological information for wetlands within the NAD.
5.0 WETLAND RISK ASSESSMENT
The wetland risk assessment is a conceptual framework to assist in predicting and assessing change in the ecological character of wetlands. The framework has been adopted by Ramsar (resolution V11.10) and is now promoted as an integral component of the management planning process for wetlands. The relevance of undertaking wetland inventories becomes apparent within this framework. A wetland inventory ultimately collects information for the wetland assessment framework. This information is also critical in order to make
recommendations for monitoring.
A central component of the wetland risk assessment is the ability to record the ecological character of a wetland. The Ecological character is the sum of the biological, physical, and chemical components of the wetland ecosystem and their interactions that maintain wetland functions and attributes. Recording changes to the ecological character of a wetland involves the development of a monitoring program, this is further discussed in Section Three –
Wetland Monitoring.
6.0 WETLAND INVENTORY METHODOLOGY
A wetland inventory essentially collects information that assists in wetland management. It can provide information for specific assessment and monitoring activities.
6.1 Study area boundaries
The project boundary is based on the NAD Natural Heritage Trust (NHT) boundary, which encompasses all of Yorke Peninsula extending north to Wilmington, east to Clare, with the south-west boundary near Two Wells. Refer to Map 1.
6.2 Site selection
The aim of the wetland selection process was to sample a broad range of inland wetlands across the Northern Agricultural Districts. Factors such as time constraints, accessibility and the project budget were limiting factors in the number of wetlands selected. Wetlands were selected initially by studying the GIS waterbody coverage for the Northern Agricultural Districts. Waterbodies within State government lands, community lands, Council-managed lands, land under management agreements and Heritage Agreements were targeted for further investigation.
A total of 29 wetlands were surveyed within the NAD, the majority of these wetlands are located in the southwest of Yorke Peninsula. Refer to Map 2 for wetland locations.
6.3 GIS Database
This project builds on GIS database initiatives undertaken by Planning SA and the Department for Environment and Heritage. GIS databases have been developed for the Murray River region by Carruthers and Nicolson (1992) and published in the form of an Atlas by Jensen et al (1996). A GIS database exists for the South East region of the state and has been published in the form of a technical report by Carruthers and Hille (1997). No other regions in South Australia have a GIS wetland database at present, although databases for the Mount Lofty Ranges, Eyre Peninsula and Kangaroo Island are being developed. One of the project objectives is to provide a digital coverage of spatial boundaries of wetlands surveyed with the NAD.
A State-wide numbering system was developed for identifying wetlands which follows the system established for the Murray River wetlands. The Murray River wetlands have been assigned the numbers S0001 to S0999. The South East region (S1000 to S1999), Eyre Peninsula, (S3000 to S3999), Kangaroo Island numbers S5000 to S5999 and the Mount Lofty Ranges (S2000 to S2999). The Northern Agricultural Districts has been assigned the numbers S4000 to S4999. The software used to produce the wetlands data is the ESRI (Environmental Systems Research Institute) geographic information system (GIS) ARC/INFO. The GIS layer was created initially from the existing land cover layer that
contained areas designated as swamps, vegetated swamps, lakes and vegetated lakes. This land cover layer was mapped from 1:40 000 colour aerial photography by the Geographical Analysis and Research Unit, Planning SA, Department for Transport, Urban Planning and the Arts.
7.0 WETLAND INVENTORY SURVEY
In developing the wetland survey, it was critical that information collected could be used for an initial assessment of wetland character. This ultimately involved the collection of physical, biological and chemical parameters. In the development of the survey form, several
methodologies were studied and adapted, these include:
Ø Butcher, R.J. (1999) Assessing biodiversity in temporary and permanent wetlands. pp 50-53 in The Other 99%. The Conservation and Biodiversity of Invertebrates, ed by Ponder, W. and Lunney, D. (1999). Transactions of the Royal Zoological Society of New South Wales.
Ø Finlayson, C.M. and Spiers, A.G. (1999). Techniques for enhanced wetland inventory and monitoring. Supervising Scientist, Canberra
Ø Fairweather, P.G. and Napier (1998). Environmental indicators for national state of the environment reporting - inland waters. Environment Australia.
Ø Maher, W. and Liston, P. (1997). Water quality for maintenance of aquatic ecosystems:
Appropriate indicators and analysis. Australia: State of the Environment Technical Paper Series.
(Inland waters). Environment Australia.
Ø Morelli, J. and de Jong, M. (1996). A Directory of Important Wetlands in South Australia. South Australian Department of Environment and Natural Resources, Adelaide.
Ø Storey, A.W. Lane, J.A.K. and Davies, P.M. (1997). Monitoring the ecological character of Australia's wetlands of international importance (RAMSAR Convention). Western Australian Department of Conservation and Land Management and Biodiversity Group of Environment Australia.
7.1 Wetland survey template
For each wetland surveyed the physical, biological and chemical information was collected. A brief outline is given below. The complete wetland survey descriptions are given in Appendix 1.
Physical parameters
• Wetland Reference Number • Wetland name
• Ramsar Site • Description of site
• Land use • Tenure
• Land element • Geology
Biological parameters
• Vegetation associations • Noteworthy flora and fauna
• Biological threats • Aquatic vegetation classes Chemical parameters
• Dissolved oxygen • pH
• Conductivity • Temperature
SECTION TWO WETLAND ASSESSMENT FOR THE NORTHERN AGRICULTURAL DISTRICTS
8.0 INTRODUCTION
Wetland assessment involves the identification and status of threats to wetlands as a basis for the collection of more specific information through monitoring. In essence, Section Two of this report analyses the survey results by looking at each survey parameter individually. This comprises a background discussion and analysis.
8.1 Wetland overview
The majority of wetlands within the Northern Agricultural District are naturally saline and are varying in environmental condition. The salt lakes located in Innes National Park are in excellent condition and are without doubt the best examples of salt lake systems on Yorke Peninsula. The ‘heel’ of Yorke Peninsula (near the township of Yorketown) is characterised by over a 100 circular salt lakes. Very little native vegetation in this area remains due to clearance for agriculture. Further north, toward the township of Minlaton, is the last remaining forest of Eucalyptus camaldulensis (Red Gum) which is located in a seasonally inundated flat.
Inland wetlands are sparsely distributed over the remainder of the Peninsula, but more saline lake systems are found further north starting at the township of Lochiel. A band of salt lakes located on the Condowie Plains runs parallel to the Hummock and Barunga Ranges. These salt lakes are in agricultural lands that are largely cleared. One of the largest lakes, located near Lochiel (Lake Bumbunga), is a source of gypsum. This band of salt lakes terminates near Crystal Brook in the north.
Several fresh water bodies are located in the Southern Flinders Ranges, with Beetaloo Reservoir contained in Beetaloo Valley being one of the most prominent. No natural wetlands were surveyed in the Southern Flinders Ranges, although it is assumed that there would be freshwater soaks within drainage lines in the Beetaloo Catchment area. Nelshaby Reserve Reservoir near Port Pirie is used as a secondary water supply and contains significant aquatic and terrestrial habitats. This waterbody was the only freshwater wetland surveyed in the region.
Map 2 illustrates the wetland survey locations in the NAD.
9.0 WETLAND LAND USE 9.1 Background
Land use within wetland areas usually dictate the level of protection and the condition of the wetland. Surrounding land uses are a major contributor to the processes that threaten wetlands. Many wetlands within the NAD are under threat from increasing salinity resulting from the clearance of native vegetation.
9.2 Analysis
Figure 9-1. On site wetland land uses
The majority of wetlands surveyed have a surrounding land use of grain and legume
production (14 sites), and most of these wetlands are in a degraded condition. Nine wetlands have a surrounding land use of conservation management; these include the salt lakes in Innes National Park, one Sanctuary (Tea-tree Swamp) and a council reserve (Gum Flat).
Land uses
4
14 9
1 2
Unknown Cropping Conservation Reserve
Recreation reserve Mining
10.0 MANAGEMENT AUTHORITY 10.1 Background
The management authority of a wetland often dictates the type and level of protection and management for the wetland. An understanding of this also allows consideration of different legislation and approaches concerning on-site management and planning for wetland sites.
10.2 Analysis
Figure 10-1. Tenure and management
The majority of sites are under private management (20 sites), five sites are managed by National Parks and Wildlife SA which are concentrated in Innes National Park, and the remaining four wetlands are managed by local government. These include Gum Flat and Nelshaby Reserve.
Management authority
1
20 4
5
Unknow n Private Local government National Parks and Wildlif e
11.0 ENVIRONMENTAL ASSOCIATIONS AND IBRA REGIONS 11.1 Background
The Interim Biogeographic Regionalisation for Australia (IBRA) is a framework for
conservation planning and sustainable resource management within a bioregional context.
IBRA regions represent a landscape based approach to classifying the land surface from a range of continental data on environmental attributes. In 1999-2000, IBRA version 5 was developed. Eighty-five bioregions have been delineated, each reflecting a unifying set of major environmental influences that shape the occurrence of flora and fauna and their interaction with the physical environment. (See:
http://www.ea.gov.au/parks/nrs/ibraimcr/ibra_95/index.html)
Environmental associations are the next level of complexity down from the IBRA regions.
These associations were first described and mapped by Laut et al (1977).
11.2 Analysis
This Wetland Inventory covers eight environmental associations. Refer to Map 3 for Environmental Associations locations.
Table 11.1 Environmental Associations
Environmental Association Number of wetlands
Innes 6
Yorketown 16
Urania 2
Bumbunga 2
Hansen 1
Glendella 1
Barung 1
Mallala 1
12.0 WETLAND AREA 12.1 Background
The area of the wetlands was calculated by using ArcView GIS based on waterbody mapping provided by Planning SA.
12.2 Analysis
Figure 12-1. Wetland Area in Hectares.
The majority of wetlands have an area between 0 and 50 ha, (18 sites). Five sites recorded areas between 51 and 100 ha and two sites recorded areas between 101 and 200 ha
(Warooka dump wetland, Lake Sunday). One site recorded an area between 201 and 300 ha (Old salt works lake) and four sites recorded areas over 300 ha, the largest being Lake Bumbunga at 1,388 ha (pictured below).
Wetland Area
5 18 2
1
4
0 - 50 51 - 100 101 - 200 201 - 300 300+
Lake Bumbunga, located south of Snowtown, was the largest waterbody (1,388 ha) surveyed within the Northern Agricultural Districts.
13.0 LANDFORM ELEMENT 13.1 Background
The landform element definitions used in the wetland inventory has been adapted from Heard and Channon (1997) Guide to a native vegetation survey using the biological survey of South Australia methodology, Section 3. Geographic Analysis and Research Unit,
Department of Housing and Urban Development. For landform element descriptions, refer to Appendix 1.
13.2 Analysis
Table 13-1. Landform element
Landform element Occurrence
Salt Lake 23
Open depression 1
Closed depression 2
Lagoon 1
Lake 1
Swamp 1
Swale 1
Wetlands are ultimately defined by the surrounding landforms. The majority of wetlands surveyed are defined as salt lakes (a lake which contains a concentration of mineral salts, predominantly sodium chloride in solution, as well as magnesium and calcium sulphate). The majority of the 23 salt lakes are distributed around the south-eastern Yorke Peninsula.
Plate 2. Inneston Lake, a typical salt lake located in Innes National Park.
14.0 GEOLOGY 14.1 Background
Yorke Peninsula forms the southern section of the Northern Agricultural Districts. The Peninsula forms an undulating, elongated landmass of low relief, bounded on both the east and west by shallow gulfs, Gulf St Vincent and Spencers Gulf. During the Teriary Period (64- 1.5 million years ago), seas inundated the majority of Yorke Peninsula and the Northern Adelaide plains initiated a sedimentary period. The major rock form during this period was limestone, which can be found across the Peninsula in the form of hardened calcrete sheets and nodules. The next geological change occurred during the Pleistocene Period (1.8 – 10,000 years ago), when the Mount Lofty Ranges were uplifted to their current height and Gulf St Vincent and the Northern Adelaide Plains were covered by rising seas. During this period Yorke Peninsula took its present shape through faulting (Corbett and Scrymgour 1973).
Further inland to the north, the geology of the Northern Agricultural Districts is influenced by the Adelaide Geosyncline, which formed during the upper pre-Cambrian 1,400 million years ago. This formed the southern Flinders Ranges and the smaller ridgelines running north- south (the Hummocks and Tothill Range). Over the next 900 years the valleys between these ridges were filled with sediments.
14.1 Analysis
Table 14-1. Geology underlying surveyed wetlands.
Geological description Number of wetlands surveyed
Undifferentiated carboniferous permian rocks 11
Alluvial/Fluvial pleistocene sediments 9
Umberatana group/Neoproterozic sturtian glacial sediments
1
Palaeoproterozic orogenic grantoids 3
Bridgewater formation 3
Holocene-lacustrine/playa sediments 3
The undifferentiated carboniferous permian rocks (11 records) and the Holocene-lacustrine/
playa sediments (3 records) are located in south-eastern Yorke Peninsula near the localities of Yorketown and Warooka. This area contains the largest concentration of salt lakes within the Northern Agricultural Districts. The Alluvial/Fluvial pleistocene sediments (9 records) are located between the ridge lines formed by the Adelaide Geosyncline in the northern section of NAD. The one record of Umberatana group containing the Neoproterozic Sturtian glacial sediments is Porter Lagoon, located near the township of Clare. Three records of
palaeoproterozic orogenic grantoids were recorded at the south-western part of Yorke Peninsula which includes Innes National Park. The Bridgewater Formation was also recorded for three wetlands in this region.
Of notable interest is the occurrence of stromatolites which are found in Inneston Lake within Innes National Park. This is one of very few examples of living stromatolites and is listed on the National Estate Register as a significant natural site (Graham 2002) The occurrence of this highlights the importance of specialised habitat provided by the saline lagoons in Innes National Park.
15.0 HYDROLOGY
The Wetland Inventory documented the average annual rainfall for wetlands surveyed and made observations on the main sources of water entering the wetlands. The average annual rainfall for the Northern Agricultural Districts is 400 mm a year, with many localities recording lower than this, for example, Wallaroo with 340 mm. Evaporation rates are high and exceed the monthly average rainfall throughout much of the year.
Surface run-off from the surrounding catchments is the main source of water for wetlands within the NAD. Groundwater connections to surface waters were not evident from field observations and little is available from published data. Sibenaler (1976) study of south- western Yorke Peninsula comments that the freshwater basin has been subjected to unsustainable extraction and is now showing signs of saline intrusions.
16.0 FLORA ANALYSIS
A large proportion of wetlands surveyed with the NAD are considered to be saline (>9500 µs or 5225 ppm/mg/L). Aquatic and semi-aquatic flora was noticeably absent in many water bodies, especially in hyper-saline waterbodies. Four wetlands recorded Ruppia (Widgeon Grass); these wetlands are located within the southern tip of Yorke Peninsula (Chain of Lakes and Tea Tree Swamp), and the two other wetlands (Minlaton Salt Lake and un-named wetland) are located near the township of Minlaton.
Soil salinity and length of time of inundation largely determine the vegetation associated with the salt lakes. Many of the salt lakes which have long periods of inundation (such as those found in south-eastern Yorke Peninsula) are devoid of vegetation. Other wetlands where the soil salinity is still high but inundation is less frequent ground cover vegetation such as samphire (Sarcocornia spp, Haloragis spp and Arthrocnemum spp) are usually present.
Melaleuca halmaturorum often forms the overstorey in these systems with Gahnia spp.
occasionally forming tussock bands in open areas between the thickets of Melaleuca halmaturorum.
Table 16-1. Vegetation associations at survey sites Dominant vegetation community adjacent to
wetland
Number of wetland
sites
Conservation significance
Melaleuca halmaturorum tall shrubland over Sarcocornia quinqueflora low open shrubland
9 Tea Tree Swamp (south-west Yorke Peninsula); also contains several species of conservation significance, this includes
Isotoma scapigera (SA Rare) and Pleuropappus phyllocalymmeus (SA
Vulnerable).
Sarcocornia quinqueflora low open shrubland over introduced grasses
15 Gum Flat located near Minlaton is included as one of these sites. This
wetland contains Eucalyptus camaldulensis var. camalduensis which is
rated as Vulnerable on Yorke Peninsula.
Eucalyptus porosa over Gahnia lanigera. 1 (un-named wetland)
Gahnia lanigera is Identified as a threatened community within the NAD.
This species is also not formally conserved.
Dominant vegetation community adjacent to wetland
Number of wetland
sites
Conservation significance
Introduced grasses 3 None
Eucalyptus camaldulensis var. camalduensis over Eremophila longifolia, introduced grasses.
1 (Nelshaby Reserve)
Provides excellent habitat for water birds and aquatic flora and fauna.
Plate 3. Tea-Tree Swamp
Plate 4. Gum Flat
Melaleuca halmaturmorum is the dominant vegetation present at many wetlands within the Northern Agricultural Districts, this species forms an effective buffer for water bodies from sediments and nutrients. Greenway (1997) discusses some further direct benefits from Melaleuca halmaturorum these include:
Hydrological benefits
• Improved water quality by filtering suspended particles and by removing, recycling, or immobilising contaminants and nutrients, thereby preventing deterioration of downstream aquatic ecosystems (eg Tea Tree Swamp).
• Provide flood mitigation by storing and detaining precipitation and run-off thus reducing flow rates and peak floods.
• Provide groundwater recharge and a water source for people and wildlife.
Ecological benefits
• Melaleuca trees are highly productive at recycling nutrients and function as long-term biomass sinks.
• During major flood events, particulate matter is washed into the rivers and estuaries to provide a food source for heterotrophic mirco-oranisms and detritivores.
• Provide both temporary and permanent habitats for a variety of flora and fauna, including roosting and breeding areas for wildlife. Some Melaleuca swamps support large ibis and egret colonies (eg Native Hen Lagoon).
• Provide vital refuges for wildlife during periods of drought.
• Melaleuca trees flower prolifically and provide a source of nectar for resident and migratory birds, bats, possums, bees and other insects. Their nectar is a particularly valuable food source for migratory honey-eaters and parrots during the autumn/winter months (eg Innes National Park salt lakes).
Threats
There are various key threatening processes which affect the majority of remnant Melaleuca halmaturorum woodlands in the NAD. These include increased nutrients moving into the water due to catchment clearance and farming practices. Resulting in dieback and a change in water chemistry which affects aquatic plants and invertebrate composition.
17.0 DEGRADATION AND DISTURBANCE 17.1 Background
Disturbances or threats are defined as any direct or indirect human activities at the site or in the catchment area that may have a detrimental effect on the ecological character of the wetland. The effect may be a low level disturbance (low level grazing) or a major threat such as water diversion schemes.
17.2 Analysis
Table 17-1. Land degradation
Degradation type Number of Occurrences
Access Tracks 11
Clearance 17
Grazing damage 2
Fence lines 15
Rubbish 8
Altered flows 3
Many wetlands contained disturbances; the two most frequent disturbances recorded were clearance (17 occurrences) and fence lines (15 occurrences). Several sites recorded impacts from domestic livestock grazing of wetland vegetation (two sites). Access tracks dissecting or traversing wetlands were also common (11 sites). A concern with many of these tracks is that they are usually formed from compressed soil and during high rainfall events, sediment often runs into adjacent wetlands. Other disturbances include rubbish dumping (8 sites, eg Munkowurlie Lagoon, Wetland 24 and Diamond Lake). Altered water flows were also recorded. This occurred at three sites, namely Nelshaby Reserve, Lake Sunday and Gum Flat.
Plate 5. Nelshaby Reserve.
Water is being diverted into the lake area in Nelshaby Reserve which has reduced
environmental flows for the Eucalyptus camaldulensis populations. This has partly resulted in the death of these trees due to the removal of the hydrological wetting and drying regime.
18.0 AQUATIC VEGETATION CLASSES 18.1 Background
Parameters for seven classes of aquatic vegetation were included in the survey. These records can indicate the types of producers (production of oxygen and plant food) within the wetland system. The diversity of classes recorded may indicate the level of aquatic
biodiversity present, the vegetation classes consist of:
Algal and aquatic moss commonly comprise Charophyta (stoneworts) and Chlorophyta (green algae) which forms macroscopic mats either attached to plants or in open water.
Algae forms the photosynthetic basis for the open water food sources in many inland waters (Boulton and Brock, 1999).
For images of green algae see: http://www.nmnh.si.edu/botany/projects/algae/Imag-Chl.htm.
Floating vascular/leaved plants have part or all of the leaves at the waters surface.
Examples include Azolla species floating ferns that host bacteria that fix nitrogen
(Romanowski 1998), Lemna, Spirodela and Wolffia (duckweeds) and members of the family Utricularia (bladderworts). Members from the family Potamogetonacea (pondweeds) are also common floating plants and can be found in a variety of habitats. All these plants are able to provide habitat for invertebrates, provide shelter for fishes and produce oxygen.
Rooted vascular plants are those rooted in the sediments with either a major proportion of material above water (reeds, rushes and sedges) or totally under water (Vallisneria spp.).
Many of these plants play a key role in nutrient cycling and provide habitat for birds, insects and aquatic invertebrates. Typical genera include Baumea, Bolboschoenus, Carex, Cyperus, Gahnia, Schoenus, Juncus, Triglochin and Myriophyllum. Myriophyllum is a distinctive
wetland genus that provides food, shelter and spawning or nesting sites for a variety of animals, from invertebrates to fish, frogs and birds (Romanowski 1998).
18.2 Analysis
Figure 18-1. Aquatic vegetation types recorded
The majority of wetlands surveyed recorded no aquatic vegetation classes (19 sites). Rooted vascular plants are the most common form of vegetation class within the surveyed wetlands.
Commonly recorded flora species included Ruppia and Myriophllum.
Aquatic Vegetation Classes
10
19 1
Rooted vascular Algal Not present
19.0 AQUATIC FAUNA ANALYSIS 19.1 Invertebrates
Macro and micro invertebrates are an essential component of the wetland food web. They are responsible for a significant proportion of the secondary production occurring in wetlands, and form two interconnected wetland food chains, a grazing food chain and a detrital food chain. Invertebrates comprise much of the diet of waterfowl populations the diversity and abundance of waterfowl can be a direct consequence of the invertebrate food supply.
19.1.1 Ecological benefits
Yen and Butcher (1997) provide some examples of direct ecological benefits that invertebrates contribute.
Tangible direct benefits:
1. Plant pollination
2. Effects on soil: soil formation and fertility.
3. Decomposition: fragmentation and recycling of dead plant and animal material.
4. Position in the food web: invertebrates are the principle food for many vertebrates.
5. Preditation and parasitism. Invertebrates are involved in the natural regulation of
populations of other species through predation and parasitism, and thus form the basis of biological control.
Indirect ecological benefits:
1. Ecosystem stability: the loss of species from highly interrelated systems is likely to cause a cascade of further losses.
2. Evolutionary time: the diversity within ecosystems over time maintains diversity.
19.1.2 Trophic dynamics
Standing water communities are dynamic systems which reflect change in many variables.
The trophic state of a wetland depends on nutrient inputs from the catchment and within the wetland (Boulton and Brock 1999). Invertebrates were collected during the Wetland Inventory and classified according to trophic levels. If samples from all trophic groups are collected, this could suggest that the aquatic ecosystem is in a reasonable state of equilibrium. The top of the food chain is occupied by vertebrate predators, including fish, water rats and water birds. These terrestrial predators can be considered to be on the top of the aquatic food chain, and provide a pathway for the export of nutrients and other material from the wetland ecosystem (Boulton and Brock 1999). These trophic levels are described below.
Primary producers
Primary producers form two groups, those that are suspended or floating and those attached to substrate or other plants. Attached macrophytes includes fringing reeds and submerged plants and periphyton (the biota attached to submerged surfaces). Suspended or floating forms generally consist of the phytoplankton and algae groups. Phytoplankton form the basic photosynthetic basis for the open water food web in most standing waters.
Consumers
There are two main types of consumers based on diet: grazers that consume plants and predators that consume other animals.
Grazers
Grazers consist of aquatic snails (Gastropoda) and some mayfly nymphs (Ephemeroptera), caddisfly larvae (Trichoptera) and beetles (Coleoptera). These groups are usually found near the edges of the water body.
Within the open water, some of the important grazers are zooplankton, including water fleas (Cladocera) and copepods (Calanoida and Cyclopoida).
Vertebrate Grazers
Vertebrate grazers generally consist of groups such as tadpoles, fish and waterbirds.
Vertebrate grazers can influence the food web considerably when attracted to water bodies in times of flood or in types of drought.
Predators
Predators include dragonfly larvae (Odonata) which tend to ambush prey and invertebrates that hunt in open water, such as diving beetles (Dytiscidae, Coleoptera) (Boulton and Brock 1999). Areas such as the littoral zone tend to have high biodiversity of grazers which in turn attracts many invertebrate predators.
19.2 Saline Systems
The majority of wetlands within the Northern Agricultural Districts contain saline wetlands.
The invertebrate composition changes with different salinities and the vegetation structure also influences invertebrate composition and abundance. Freshwater organisms in Australia generally tolerate salinities up to about 300 Ms/m (3000 EC), beyond this there is a change in community composition, with decreased richness and increased abundance (Williams, 1998; Skinner et al, 2001).
A high diversity of invertebrates can occur within salt lakes, examples include rotifers, anostracan, cladocerans, calanoid copepods and ostracods. Fishes are usually absent from saline lake systems and the top consumers are mostly water birds. In general, invertebrate species richness in salt lakes declines with increasing salinity, but at intermediate salinities where many species tolerances are broad, other factors such as biological interactions and pH will affect community composition (Skinner et al 2001; Williams, 2000). Studies by Skinner et al (2001) indicates that salinization shifts invertebrate community structure and algae tends to also become dominant at the higher salinity levels. This could lead to insufficient food for animals higher in the trophic level, including fish and waterfowl.
19.3 Analysis
Analysis of invertebrates is discussed in four areas.
1. frequency of invertebrate occurrence 2. trophic levels
3. number of invertebrate records for each surveyed wetland
19.3.1 Frequency of invertebrate occurrence
Table 19-1 lists the invertebrate species identified from collections made during the Wetland Inventory in December 2000, with the frequency of occurrence given against each identified invertebrate. A total of 35 species were recorded, with 18 species recorded once and 17 species recorded more than once. Of these 79 species, two species recorded six or more occurrences (Diacypris sp. seven occurrences, Mytilocypris cf. Ambiguosa six occurrences and Mytilocypris cf. tasmanica chapmani, six occurrences). Ten sites recorded no species.
Table 19-1. Frequency of invertebrate species occurrence
Identified invertebrates Frequency of
occurrence
Cypricercus sp. 3
Mytilocypris cf. Ambiguosa 6
Mytilocypris cf. tasmanica chapmani 6
Boeckella triarticulata 2
Metacyclops mortoni 2
Daphnia carinata 1
Lynceus sp. 2
Agraptocorixa sp 3
Diaprapacorus sp 1
Austrolestes annulosus 1
Anisops sp 3
Diacypris cf spinosa. 2
Calomoecia salina 5
Diacypris sp. 7
Daphniopsis pusilla 4
Parartemia cf zietziana 5
Coxiella sp. 1
Diacypris cf paracompacta 4
Apacocyclops dengizicus 1
Mesochra baylyi 2
Austrochiltonia australis 2
Alona sp. 1
Macrothrix spp 3
Austrolestes analis 1
Daphniopsis australis 1
Odontomyia larvae 1
Austrolestes sp 1
Mortoni 1
Berosus sp 1
Tanytarsini sp 1
Australocyclops australis 1
Austrolestes sp 1
Hesperocordula sp 1
Procladius sp 1
Chironomus sp 1
Invertebrate identification by Robert Walsh, 2000.
19.3.2 Trophic levels
Invertebrate composition analysis is affected by the study of trophic levels present in each wetland. Conclusions made about the ecosystem health of a wetland based on the
invertebrates could not be made due to the limited sample size, and can only provide an indication at the time of the sampling.
Invertebrate scoring method
Invertebrate scores were assigned for each wetland, each sample was identified to family level and the trophic level of each family recorded. From the samples identified the diversity and abundance was recorded and the following scoring system was developed.
Score 1 = (Low) sampled one family from one trophic level, usually from a lower level trophic level, (eg detritivores and herbivores).
Score 3 = (Moderate) sampled more than one family with representatives from one or more trophic levels, (eg herbivores and carnivores).
Score 5 = (High) sampled more than two families with representatives from three or more trophic levels, (eg detritivores, herbivores, omnivores and carnivores).
Figure 19-1. Invertebrate scores.
Nine sites recorded high trophic levels included the freshwater wetland of Nelshaby Reserve, Gum Flat and Inneston Lake within Innes National Park. Wetland sites that received a
moderate score are characteristically well vegetated and are protected under formal conservation. Three sites are within Innes National Park, namely Deep Lake, Brown Lake and Chain of Lakes. At fourth site (Tea Tree Swamp) has sanctuary status. Seven sites received a low score, the majority of these sites are located on private lands and have been degraded through land clearance.
Trophic level scores
7
4 9
Low Moderate High
Table 19-2. Trophic scores
Wetland number Wetland name Trophic score
S4002 Chain of Lakes 3
S4003 Brown Lake 3
S4004 Deep Lake 3
S4005 Inneston Lake 1
S4006 Inneston Lake 2 5
S4018 Diamond Lake 1
S4010 Old Salt Works Lake 1
S4014 Lake Sunday 1
S4016 Yorketown Center Lake 1
S4017 Pink Lake 1
S4020 Minlaton Salt Lake 5
S4019 Gum Flat 5
S4021 Un-named Wetland 5
S4025 Un-named Wetland 3 5
S4026 Native Hen Lagoon 5
S4027 Bookamurray Lagoon 5
S4028 Nelshaby Reserve 5
S4029 Porter Lagoon 1
S4007 Tea Tree Swamp 3
19.3.3 Invertebrate records for each surveyed site
Table 19-3 lists the number of invertebrate records identified at each wetland site surveyed.
Bookamurray Lagoon and Gum Flat both returned high abundance levels.
Table 19-3. Number of invertebrate records for wetlands
Wetland number Wetland name Number of records
S4002 Chain of lakes 2
S4003 Brown Lake 3
S4004 Deep Lake 2
S4005 Inneston Lake 1
S4006 Inneston Lake 2 5
S4018 Diamond Lake 1
S4010 Old Salt Works Lake 1
S4014 Lake Sunday 1
S4016 Yorketown Center Lake 1
S4017 Pink Lake 1
S4020 Minlaton Salt Lake 5
S4019 Gum Flat 11
S4021 Un-named Wetland 6
S4025 Un-named Wetland 3 4
S4026 Native Hen Lagoon 7
S4027 Bookamurray Lagoon 12
S4028 Nelshaby Reserve 7
S4029 Porter Lagoon 1
S4007 Tea Tree Swamp 3
20.0 AVI-FAUNA
The inventory did not record bird activity within the surveyed wetlands, however on five wetlands various species were recorded, these are listed below.
Table 20-1. Avi-fauna
Wetland Scientific name Common name
Gum Flat Egretta novaehollandiae White Faced Heron
Vanellus miles Masked Lapwing
Himantopus himantopus Black Winged Stilt Anus superciliosa Pacific Black Duck Minlaton Salt Lake Himantopus himantopus Black Winged Stilt
Vanellus miles Masked Lapwing
Anus gracilis Grey Teal
Aythya australis White Eyed duck
Unnamed Wetland Himantopus himantopus Black Winged Stilt
Vanellus miles Masked Lapwing
Native Hen Lagoon Anus gracilis Grey Teal
Himantopus himantopus Black Winged Stilt Gallinula mortierii Black-tailed Native Hen
Nelshaby Reserve Cygnus atratus Black Swan
Ardea pacifica White Faced Heron
Tachybaptus novaehollandiae Australasian Grebe
Fulica atra Eurasian Coot
Gallinula ventralis Black-tailed Native-Hen
Anus gracilis Grey Teal
21.0 WATER CHEMISTRY
Chemical processes in permanent and temporary waters are extremely complex. The chemistry of the water directly influences the biological process (such as photosynthesis).
The physical features of the wetland also has a strong influence on both the chemical and biological processes. These three factors (chemical, physical and biological) are constantly in a state of flux and change. Changes in these parameters are most pronounced in temporary wetlands where a wetting and drying cycle occurs. The majority of wetlands within The Northern Agricultural Districts have seasonal water regimes, filling during winter and remaining dry throughout summer.
Figure 21-1. Temporary wetland cycles Depth
Water Temp
Dissolved Oxygen
Conductivity
pH
Nutrients
DRY FILLING FILLED DRYING DRY
TIME
Pioneer species Core species Core species Core species
Peak flow species Tolerant lentic species
Brock and Boulton (1999) state that changes in water quality during drying and filling depend on factors including:
1. sediment properties (composition, nutrients and organic content) 2. type of drawdown (gravity or evaporative)
3. severity of drying (rate of drying, temperature, weathering)
4. conditions of refilling (origin of water, degree of sediment disruption).
Figure 21-1 shows the changes in chemical variables over time during the phases of filling and drying in temporary wetlands. Seasonal changes in invertebrate composition is also noted.
21.1 pH
21.1.1 Background
The pH value of water indicates how acidic or alkaline it is on a scale 1-14. Acids have a low pH of about 2 for a strong acid like sulphuric acid and about 4 for a weak one like lactic acid.
Alkalis have a high pH of about 12 for sodium hydroxide. Pure distilled water has a pH of 7 which is neutral. From pH 7 to 0, a liquid becomes increasing acidic and from pH 7 to 14, a liquid becomes increasingly alkaline.
Generally in South Australia, the pH of natural water ranges between 6.0 and 8.5 with most water bodies in the range of 7.0-8.0. The higher pH of natural water bodies is caused by high bicarbonate levels in the water and can raise the pH during the day and lower pH at night. Chemicals entering the water can also affect the pH.
PH is an important environmental indicator. At extremely high or low pH values, the water becomes unsuitable for most organisms.
Figure 21-2. pH values
14 HIGH (Alkaline)
10 MEDIUM 9 MILD 8 PRISTINE
6 MILD 5 MEDIUM 4
HIGH (Acidic)
1
21.1.2 Analysis
The average pH of wetlands surveyed ranged between pH 6 and 8 (22 sites), which falls into a neutral pH value. Five sites recorded a pH reading of
alkaline (pH between 9-14) Un-named Wetland 3 and Gum Flat recorded the highest pH readings of 9.57 and the lowest recorded pH value was 7.45 at Lake Bumbunga.
21.2 Conductivity 21.2.1 Background
Salinity is a serous threat to aquatic ecosystems throughout Australia. The National Land and Water Resources Audit 2001 estimates that up to 41,300 Kilometres of streams could be salt affected by 2050 and that 24 of 79 river basins studies exceeded recommended salinity parameters.
Salinisation causes serious biological effects including;
• changes to the natural character of water-bodies
• loss
of biodiversity
• less salt-tolerant species are replaced by more tolerant species.
These effects can cause permanent degradation and ecosystem collapse (Williams 2001). The loss of biodiversity is probably greater than generally realised since very little research has occurred in this area. Salinisation also leads to significant decreases in water quality for irrigation and water supply (leading to high economic costs); the loss of amenity and aesthetic values is also of concern.
Limited data are available for assessing the risk of adverse effects from salinity in different ecosystem types, particularly wetlands. The Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2001) tables wetlands in South Australia with ‘no data’ related for assessing adverse
effects of salinity. Guidelines developed for Western Australia state that lakes, reservoirs and wetlands should have a salinity range between 300-1500µs.
Values at the lower end of the range are during rainfall events, those at the higher range are found in salt lakes and marshes.
Figure 21-1 is based on the salt measurement conversions guide from the
Land Management Society Inc. This guide indicates salinity levels and
tolerance levels for different parameters. These guidelines form the basis of
analysis for the Wetland Inventory.
21.1.2 Analysis
Table 21-1 outlines the salinity recordings for 26 wetlands. Nelshaby Reserve recorded the lowest reading of 566 µs, which is regarded as freshwater. One wetland (Gum Flat) recorded brackish readings and a total of 22 wetlands recorded high to extreme salinity levels.
Table 21-1. Salinity guidelines.
Salinity in micro- siemens per cm
µµµµs/cm
Water definition
Guides Surveyed Wetlands
0 - 900 Fresh Fresh Nelshaby Reserve (566 µs)
900 - 2700 Marginal Maximum for hot water systems, dam water starts to go clear, maximum for people.
No records
3000 - 9100 Brackish Maximum for milking cows and poultry, crop losses start.
Gum Flat
9500 + Salt 9500 = Yabbie growth starts to slow, maximum for horses.
14500 = Yabbie growth ceases 64.0 Ms/cm = Sea Water 100.0 Ms/cm = Limit for salt bush
A total of 23 wetlands fall into this category with the highest reading occurring at Lake Bumbunga (185.0 Ms/cm)
Plate 6. Nelshaby Reserve.
Nelshaby Reserve near Port Pirie recorded the lowest conductivity reading of 566 µµµµs
