Hopetoun Inventory 21-01-08

Wetland Conservation at Hopetoun WA

Hopetoun Wetland Suites: Inventory and Assessment.

A report produced by Green Skills for South Coast Natural Resource Management Inc.

Compiled by Wetland Project Officer Tim Frodsham January 2008

Hopetoun Wetland Suites: Inventory and Assessment.

A report produced by Green Skills for: South Coast Natural Resource Management Inc.

Compiled by Wetland Project Officer Tim Frodsham January, 2008

Cover Photograph: Aerial view of Drainage to Hopetoun Wetlands November 2007

Acknowledgements

Green Skills would like to thank the following organisations and people for their involvement and assistance with the production of this report.

Support and funding and digital information through the South Coast Natural Resource Management (SCNRM) and the Federal Governments’ Natural Heritage Trust (NHT) and National Action Plan for salinity and Water Quality (NAPSWQ).

Support and digital information from South Coast NRM, Kevin Hopkinson, Department of Water (DoW), and GreenSkills staff.

Catchment information and hydrology from John Simons and Angela Massenbauer, Department of Food and Agriculture (DAFWA) Esperance.

Aerial photography by Tim Frodsham and Andy Chapman.

Site reconnaissance and habitat values from Andrew Chapman, see Appendix 2 for full report.

Proof reading of final inventory by Alan Peerless, Justin Bellanger and Kevin Hopkinson

All other people who assisted in any manner with the production of the report including Green Skills, Ravensthorpe Agriculture Innovation Network, Department of Water, Department of Environment and Conservation, Water Corporation, and Department of Agriculture and Food Staff.

The author would especially like to thank Andy Chapman for his assistance and provision of background material for this report. Similar thanks go to Basil Schur and other Greenskills staff for their assistance.

Feedback: Do you have any comments or feedbac u would like to give?

This report is intended to generate community discussion as to the most effective management practices that can be incorporated into the catchment planning activities of the Wetland Systems of the Hopetoun area. A complete management plan will be produced by March 2008. If you have any comments on the recommendations provided in this report, we would like to hear from you. Comments can be directed to: Tim Frodsham Wetlands Project Manager P.O. Box 577, Denmark W.A. 6333 Ph: (08) 9848 1019 Email [email protected] Web: www.greenskills.org.au Tel: (08) 9848 1019

Contents Acknowledgements ...... 3 Feedback: ...... 3 1.Introduction ...... 4 2 Background ...... 5 3. Previous studies ...... 5 4. Purpose of Present Assessment ...... 5 5. Methods ...... 5 6. Location, land tenure, and land use ...... 6 7. Geological ...... 7 8. Hydrological ...... 8 9 Climate ...... 9 10 Aboriginal Heritage ...... 9 11 Biological ...... 9 11.1 FLORA ...... 9 11.2 BIRDS ...... 10 11.3 FISH USE OF HOPETOUN WETLANDS ...... 10 12 Water quality of Hopetoun wetlands ...... 10 13 Macroinvertebrates ...... 10 14 Acid Sulfate Soil Tests ...... 11 15 Description of wetlands ...... 12 16 Conclusions ...... 13 17 References ...... 14

Appendix 1: THE DUNNS LAKE SUITE OF WETLANDS – AN ASSESSMENT OF VALUES, CONDITION AND THREATS, Andy Chapman, unpublished data, 2007, from a Wetland survey contracted by Greenskills Appendix 2: Photographic Plates of Study Area Appendix 3: Hopetoun Wellfields’ map in Appendix 3 Appendix 4: Map of the Hopetoun Wetlands area. Appendix 5: Invertebrate data for wetlands in the Hopetoun area Appendix 6: Aboriginal sites and surveys documentation

1. Introduction On the south coast of Western Australia, as elsewhere, there is increasing acknowledgment of the value of wetlands. This recognition includes their utility as a component of natural systems. Such service includes their capacity to perform maintenance to water quality, their visual attraction, conservation value (significantly for avi-fauna, and for recreational amenity. In addition there is the respect that some catchment activities can be contrary to these values. Additionally, the ecological service functions of wetlands include nutrient filtration, indicators to ground water

4 processes, and also flood control. In this sense they are reflective of impending upstream processes that may be harmful to other areas as well as for wetlands.

2 Background

There are four distinct wetland systems of relevance that have been studied here. The definition and classifications of wetlands do vary, but the definition derived from the Ramsar international convention on wetlands suggests:

“areas of seasonally, intermittently or permanently waterlogged soils or inundated land whether natural, saline or otherwise, fresh or saline. Eg. Waterlogged soils, ponds, bilabongs, lakes, swamps, tidal flats, estuaries, rivers and their tributaries”.

(Wetlands Advisory Committee, 1977 [from Semeniuk, 1998]).

The five wetlands studied and presented in this report will be defined as Dunns Lake, Companion Swamp, and Triple Swamp. Triple Swamp is composed of two larger wetlands containing water, collectively known as ‘Twin Swamps’; Twin Swamp 1 and Twin Swamp 2. The third wetland in this system is much smaller, and dry.

3. Previous studies

This report draws on previous work done by Chapman (2006), Frodsham (2006), and other work that is referenced in this document. Work recently conducted on groundwater conditions is briefly mentioned in this document.

4. Purpose of Present Assessment

The purpose of this assessment is to gain and interpret some comparative data on the values and condition of these wetlands. Although fieldwork was confined to the wetlands themselves and their immediate surrounds, it is envisaged that wetland condition and processes are determined by events in their catchments. It is envisioned that the data in this document will be useful as a planning tool for allocating funding to on ground works, as well as for informing better planning guidelines for peri-urban developmen nearby these wetlands. In short it is designed to not only communicate values and character of these systems, but also to inform a better understanding of their resource condition through the work presented here.

5. Methods

Field work was conducted over four days in November 2007. Methods for this are outlined by Chapman (2007) in Appendix 1.or each wetland the following data were collected:

• Nature and condition of the littoral vegetation with particular emphasis on manifestations of degradation due to salinisation, waterlogging, and weed invasion.Bird use of both the littoral vegetation and the wetland habitats.

• Water quality parameters of electrical conductivity, pH, dissolved oxygen concentration, and temperature were measured with a WTW Multiline P4 instrument. 1

• At Dunns Lake the variation of these parameters with depth was measured from a kayak.

• A water sample from each wetland was analysed for total nitrogen and total phosphorus by the Centre for Excellence in Natural Resource Management in Albany. See also Appendix 1 (Chapman (2007:4) for salinity criteria used in assessment (Table 3).

• For Dunns Lake and the adjacent Companion swamp the drainage into the wetlands was followed up by walking to examine its origin and factors affecting its quality and quantity. Tests were made for acid sulphate soil potentials over a transect leading to Companion Swamp (from its drainage catchment).

• Macroinvertebrate data were collected for three of these wetlands; Dunns Lake, Companion Swamp, and Twin Swamp 2 (Southernmost swamp). The methods used for this were standard to the collection of invertebrate data, as described by Butcher, pers comm (2007).

• An aerial flight on 6 November 2007 enabled photography, allowing for an appraisal of the wetlands and the viewing of some factors affecting their drainage.

6. Location, land tenure, and land use

The suite of wetlands studied for this report consists of three separate subsystems; the distinctive and well known Dunns Lake and a companion wetland 0.5 km to the North East a small constellation of wetlands 1.5 km ESE of Dunns Lake – the ‘Triple swamps’ and two wetlands 4.5 km ENE of Dunns Lake – the Twin swamps. These wetlands are in areas vested in the crown. See Figure 1 and Table 1 for coordinates. Further information on these topics can be found in Chapman (2007) in Appendix 1. See also Plate 1 in Appendix 2, which gives an overview of the area to the western aspect. A location map showing Hopetoun in relation to these wetlands is also available in Appendix 4.

The dominant type of land tenure and use outside of the crown reserves housing these wetland systems is private or freehold tenure for agriculture, notably wheat/cattle and cereal cropping, as illustrated by Plate 2 in Appendix 2. This shows the drainage to Dunns Lake and Companion Swamp from upstream properties in the Hopetoun area.

1 “WTW Multiline P4” is the brand of water quality testing device used for this study. 6

Recent and ongoing clearing activity to expand agricultural land area and intensified stocking will further increase downstream pressures (sediment transport, erosion and vegetative changes) on coastal wetland systems to adapt to this change (Plates 4 and 5, Appendix 2) very low gradient in topography is indicated by the dispersed nature of semi-saturated sheet flow across property boundaries. Much of this flow is saline, as evidenced by the condition of the vegetation in the floodplain. See the cover photo for this report, as well as Plate 3, Appendix 2.

7. Geological The swamps examined in this assessment are sandwiched in a narrow band some 3 km wide parallel to the coastline between Quarternary aeolian and marine sediments of sand, clay and limestone on the southern side and Archaen rocks to the northern side. The regolith for the immediate area of these four swamps is primarily quaternary sands and lacustrine sands, being re-worked deposits in layered succession. See Figure 1 (below), for an illustration of the distribution of these systems. Aeolian sediments include sands raised into dunes to 12 m high. These date from the Holocene period, some 7000 to 9000 years ago. The area is also known to contain porous substrates of karstic sediments, leading to sinkholes (Plate 6, Appendix 2) in coastal limestone formations. These are connected to the local groundwater system, but are not in themselves wetlands. The swamps themselves, when dry, have exposed alluvial sediments of clay and silty clay (Plate 7, Appendix 2). Further to the north, a small section of the Jerdacuttup Plain, and draining into these lakes and swamps, is underlain by Tertiary sediments of Pallinup Siltstone. Sandstones and claystones are also deposited, along with a lot of salt, when the sea extended inland further than it does at present. To the north east, some 90% of the Jerdacuttup Plain has been cleared for agricultural production. See Plate 8, Appendix 2, for an overview of this landscape profile.

Figure 1: The Hopetoun area is overlain by a combination of calcareous sands and lacustrine deposits dating from the quartenary period. The Quaternary roughly covers the time span of recent glaciations, including the last glacial retreat. An occasional alternative usage places the start of the Quaternary at the onset of North Pole glaciation approximately 3 million years ago and includes portions of the upper Pliocene. The 1.8–1.6 million years of the Quaternary represents the time during which recognizable humans existed. Some people do not recognize the Quaternary and consider it an informal term included in the Neogene, as can be seen from the 2003 edition of the International Stratigraphic Chart, published by the International Commission on Stratigraphy. http://en.wikipedia.org/wiki/Quaternary. Accessed on 10-12-07). Scale here is 1: 100 000, with gridlines equaling 1000m intervals.

8.Hydrological

Hopetoun is situated upon a coastal plain adjacent to the South Coast, with a narrow band of coastal dunes along the coast-line. Rainfall ranges from 500 to over 600 mm per annum and recharges aquifers in the dunal sands and deeper sediments. Water Corporation’s intention is to install a de-salinisation unit to enlarge capacity from wells that intercept these aquifers for public supply (Fred Shier, pers comm ., 4/09/07). Hopetoun has until recently relied on raintank supplies for drinking water (AGPS, 1977:36). The demand for water from the recently established Ravensthorpe Nickel Project has been largely satisfied by a desalination unit, drawing marine water from Masons’ Point, some 30kms to the East of Hopetoun. Appendix 2 is a map showing the location of the Water Corporation's production wellfields, both active and planned, as well as observation wells for monitoring in the Hopetoun area. The wells have been marked as existing production wells, monitoring wells and proposed production wells. The Town wellfield has the most wells and has an allocation of 70ML/year, which is a recent increase from 40ML/year. The Springdale wellfield is east of the Jerdacuttup River and has an allocation of 100ML/ year; The Water Corporation has applied to the Department of Water to increase that allocation to 150ML/ year (Andrew Jones, pers comm ., 10/12/07). The proposed wells west of the Jerdacuttup River have been drilled and are in the process of being

8 equipped. Water Corporation has applied to the Department of Water for an allocation of 75ML/year for these two wells (Andrew Jones, pers comm ., 10/12/07).

In addition to the existing and proposed wellfields, Water Corporation states it currently has a planning project underway to address the long-term water supply needs of Hopetoun and Ravensthorpe (Andrew Jones, pers comm., 10/12/07).

Unfortunately, groundwater monitoring data are currently limited to the production wells and observation wells close to the wellfields. The location of these data collection points and the likelihood that they reflect drawdown effects from pumping means that they are of little use in characterising the groundwater and groundwater flow systems in and around Dunns Lake. Groundwater modelling by the Water Corporation is restricted to the area around the Town wellfield and the proposed wellfield west of the Jerdacuttup River. The production bores are installed to abstract groundwater to meet the projected demand for future urban growth,and the wells are operated in accordance with the licence to take water issued by the Department of Water. Monitoring of groundwater levels by the Water Corporation in and around the production wells is intended to observe for potential adverse effects on the Jerdacuttup River, Jerdacuttup Lakes and the Hopetoun wetlands are avoided.

9 Climate

The climate of the area is classified as ‘dry Mediterranean’ by Bagnouls & Gaussen (1957), cited by Beard (1981). Chapman (2007:1) in Appendix 1 provides commentary on this climate, with data for mean annual rainfall, and extreme weather events.

10 Aboriginal Heritage

The Department of Indigenous Affairs lists only one site of indigenous significance in the area. It is a gnamma [watering] hole near Hopetoun itself. The site itself is on interim register.

The data for this appear in Appendix 6.11 Biological

11.1 Flora

Prior to clearing for agriculture, mining and other human activity, much of the area nearby these wetlands was covered by scrubland heath and woodlands of small eucalypts; in most cases large plant species are rare. The most common woody plants are: Banksia, ‘Christmas Tree’ (Nuytsia floribunda), Hakea, and Acacia (AGPS, 1977:36). Sofoulis (1958 ~), and Beard (1969, 1972) have produced maps and notes on the vegetation of the adjacent Lake Johnston and Newdegate 2 1:250 000 map sheets, and much of this information is relevant to the Ravensthorpe Sheet area (AGPS, 1977:36). Of particular interest is the ‘Eucalyptus preissiana-Dryandra quercifolia association’or ‘Barren thicket’ (Beard, 1972) which is confined to soils associated with the Proterozoic Mount Barren Beds. Its presence in areas of no outcrop suggeststhe Mount Barren Beds lie beneath the soil cover. Beard suggests a close correlation between floral types and

9 lithological units of the Mount Barren Beds on the Newdegate Sheet (AGPS, 1977:36). Flora data are detailed for each wetland in the section below: ‘Description of Wetlands’, as well as more detailed data from Chapman (2007) in Appendix 1.

11.2 Birds

Assessments in Appendix 1 recorded 56 species of birds including 19 species of waterbird that use these wetlands and their littoral vegetation (Chapman, 2007). Despite nascent indications of fragmentation of the littoral flora from broad mortality via de-oxygenation from extended overflooding, this study area still offers valuable habitat not immediately accessible elsewhere for broader ranges of birds other than waterbirds.

Chapman (2007:9) observed that waterbird use was not extensive in these study areas; part of the reason for this is the small size of these wetlands, with modest shoreline lengths, and no exposed open water edges. With high water levels, these wetlands clearly do not provide habitat for an extensive array of wading shorebirds, notably trans-equatorial migrants. Very limited waterbird breeding was evidenced by observations of only two recently used nests of only one species- the Black Swan (Cygnus atratus ). See detail for this in Appendix 1 (Chapman, 2007:9). Bird uses are also briefly mentioned for each wetland in the section below: ‘Description of Wetlands’.

11.3 Fish use of Hopetoun wetlands

Chapman (2007) has documented fish presence in these wetland systems. The data for this appears in Appendix 1. Because of comparatively narrow range of feeding possibilities and physiological tolerances offered by these wetlands, there was only one species of fish founded in this survey, the Swan River Goby, ( Pseudogobious olorum ). Details of this finding are available in Chapman (2007: Appendix 1 – data for fauna observations).

12 Water quality of Hopetoun wetlands

Water quality data is contained with Chapman (2007: Table 3), and this includes results for Phosphorus and Nitrogen are available. Levels for Nitrogen & Phosphorous are very high and beyond normal tolerances of most natural systems. 13 Macroinvertebrates

Aquatic Macroinvertebrates were sampled for three of the five wetlands (Dunns Lake, Companion Swamp, and Twin Swamp 2). Of the other two wetlands, one was difficult to access (Twin Swamp 1) and the other was dry. The data for these are presented in Appendix 5. They show little abundance observed for Chironomid larvae. Ostracoda was the only invertebrate taxa common to all sampled systems. Typically, zygoptra were found in the least saline areas, and were not able to readily inhabit more saline aquatic systems. Not including Dunns Lake, there are no comparative data for invertebrate numbers in the other wetlands investigated, here. Previous data for aquatic invertebrates in Dunns Lake indicates the presenceof nematoda, brachionidae, cyprididae, copepoda, amphipoda, coleoptra, diptera and hemiptera, but their abundance is not noted. (Halse et al , 2004).

14 Acid Sulfate Soil Tests

A linear transect of 4 sampling points as used to measurefor acid sulfate potential in soils the study area between a culvert on Dunns Lake Rd and Companion Swamp. This transect can be observed in Plate 15 in Appendix 2, of this report. T transect was established in an area with high soil moisture. The data for this are presented below, in Table 1. The transect was 300 – 400 m long, extending from a road culvert to the swamp. The transect followed the drainage line and hence not in a straight line. The gradientwas approximately 0.5% to 1%. Upstream from this culvert is a large area of land on offer for peri-urban development. See Plate 16 in Appendix 2, of this report. As can be seen from the photographs of soil profiles shown below in Table 1, this is a waterlogged area, with a dense of organic material, mainly from algal ‘mats’. Soils were sampled to a depth of 0.15 m.

Table 1: Measurements for acid sulphate soil potential in a selected transect Site # Site image Soil profile N E Soil Soil Soil Soil Quality ‘culvert’ Co pHF pH pHFOX of FOX transect test (direct) (DI) reaction

1 62428872 236774 18.0 6.98 6.97 5.52 L-M

2 n/a n/a 28.0 5.81 6.25 4.48 M

3 6242385 236975 22.0 6.66 7.00 4.62 M

4 6242802 237077 26.6 6.34 6.78 6.13 L-M

Data for Site 3 indicate a strong source of potential acidity, possibly pyrite. The pH FOX , is a field test used to determine acid potential of a soil when compared with the pH F (pH of soil measured in deionised water). In general, the pH FOX readings do appear to be quite low in comparison with was recorded for pH F.. As the pH scale is logarithmic, the difference in pH before and after the pH FOX test showed a decrease of 2 pH units, which represents approximately a 100 fold increase in acidity. Therefore a strong source of potential acidity is present in the soil at site 3, most probably pyrite. Sites 1 and 2 indicated there could be an acid source, possibly pyrite but the

11 results were inconclusive; more measurements are required to ascertain a clearer understanding of the variability in the data.

15 Description of wetlands

The results for the biological inventory Dunns Lake and Companion Swamp, and for Triple Swamps, are available in Appendix 1 (Chapman 2007:4). They are briefly summarised below

Water quality tests showed above normal levels for Nitrogen and Phosphorous for all wetlands. Dunns Lake has maximum dimensions of 300 x 150 m with an area of c. 2.5 ha. See Plate 9, Appendix 2. Dunns Lake and Triple Swamp are respectively classified as B8, B14, according to Chapman (2007; section 1.6). As most of the wetland is an open water surface it is more appropriately described as a lake than a swamp. This also serves to emphasise its distinctive nature compared to other local wetlands. The inner littoral vegetation is mature Melaleuca cuticularis woodland. Inner littoral vegetation is struggling and beginning to show signs of broad scale die-off, as seen in Plate 10, Appendix 2. The water depth was c. 2.0 m at the centre. Observations suggest that water levels to 3.6 m have been present in the past. Weeds were present and are detailed Appendix 1 (Chapman 2007:5). They may be determined as ‘uncommon’, and species recorded appear in Chapman (2007:5).

‘Companion swamp’ has an area of c.2.0 ha. See Plate 7, Appendix 2. Entirely dead Melaleuca cuticularis and Eucalyptus occidentalis occupy the entire wetland area. See Plates 10 and 11, Appendix 2. There is a poorly defined drainage channel to the west and north of Companion Swamp; it is dominated by Melaleuca cuticularis and M. brevifolia to 3 m. Other plants present are detailed by Appendix 1 (Chapman 2007:5). A low and eroded dune to the south of this wetland prevents it draining through into Dunns Lake. Depth measurements made ranged from 0.25m-0.50m. There were no weeds observed here.

Drainage into Dunns Lake and Companion Swamp appear to be influenced by extensive alteration to by human activities, and that this is likely to have had impacts in salinity and flooding levels residence time. See Appendix 1 (Chapman 2007:6) for more details.

The ‘Triple swamps’ consist of three separate wetlands the largest of which is triangular (Twin Swamp 1) with a north – south baseline and apex pointing due west and an area of c. 1.5 ha. See Plate 7, Appendix 2. Two smaller, circular wetlands, one <1 ha (Twin Swamp 2) and the other one (which is dry) is only 20 –30 m in diameter, are due east between the triangular wetland (Twin Swamp 1) and the rehabilitated quarry area (for limestone road base). The two larger wetlands appear to have been former healthy wooded swamps with mature swamp paper bark ( Melaleuca cuticularis ) and yate ( Eucalyptus occidentalis ) trees. Both were formerly B14 ‘wooded swamps’ according to Chapman (2007; section 1.6). At both wetlands all internal trees are now dead. (See Plates 12 and 13, Appendix 2). See Appendix 1 (Chapman 2007:6) for details of plant communities here. See also Plate 14 in Appendix 2 for a snapshot of a locally existing plant community. Weeds were not observed here. Depth was not accurately measured due to these wetlands inaccessibility.

The hydrology and relationship of ‘Triple swamps’ to the water table is beyond the scope and expertise of this assessment. There is no recognisable coordinated drainage into these swamps, and Chapman (2007:6) in Appendix 1 discusses the possibility that water levels are maintained by ground water inflow.

16 Conclusions

The threat most evident is that salinity and extended residence time of flood water appear to be the main cause of large scale mortality of fringing vegetation Chapman (2007:9) states that interpretation of regrowth, morbidity and deaths of Melaleuca cuticularis is likely to be instrumental in managing these wetlands. The cause of death in unknown but prolonged high water levels and increased residence time of water in soil is indicated. Recent and ongoing clearing activity to expand agricultural land area and intensified stocking will further increase downstream pressures (sediment transport, erosion and vegetative changes) on coastal wetland systems to adapt to this change (Plates 4 and 5, Appendix 2).

Chapman (2007:8) relates that dissolved oxygen levels were high, due to high photosynthetic activity of flowering plants and aquatic algae in situations of limited shading of water bodies experiencing intense sunlight. For example, at the ‘triple swamps’ system, the only one of these three wetlands that showed very high levels of dissolved oxygen (double compared to its associated wetlands), held the water weed- Ruppia megacarpa .

Water quality data is contained with Chapman (2007: Table 3), and this includes results for Phosphorus and Nitrogen. Levels for Nitrogen and Phosphorous recorded for these systems are very high and beyond normal tolerances of most natural systems. Reasons for this may be attributed to run-off of these nutrients from upstream agricultural areas.

These wetlands clearly do not provide habitat for an extensive array of wading shorebirds, notably trans-equatorial migrants. Prolonged flooding levels and loss of tree habitat for these birds may be attributed to this. Fish use of these wetlands is limited to one species only, that of the goby ( Pseudogobious olorum ).

The field testing for sources of potential acidity at sites 1 and 2 was inconclusive, though indicated there could be pyrite or other potential source of acidity present. At Site 3, high potential acid sources in the soil profile (possibly sulfides) were . Informed interpretation of data suggests that another round of tests, including using a hydrochloric acid (1MOL) test for carbonate levels (typically calcium carbonate) in these soils will help gain clarity on this situation. The presence of pyrites can also only be confirmed by laboratory testing. Field testing at Site 4, indicated little potential acidity was present. However, there could be potential acidity at a greater depth. (Adam Lillicrap, pers comm. , 13/12/07).

Weeds do not currently rank as a high priority of threat to this wetland area. There is no evidence of phytopthera noted in the area. Groundwater studies may be of value to a better understanding the hydrology of the area, especially in connection with ascertaining any groundwater relationship between the wetlands in the ‘Triple Swamps’.

17 References

Australian Government Publishing Service, Canberra 1977 Geological Survey Of Western Australia. 1 : 250 000 Geological Series-Explanatory Notes Ravensthorpe Western Australia Sheet Si/51-5. International Index. Compiled By R. Thom, S. L. Lipple, and C. C. Sanders

Beard, J.S. (1981) The vegetation survey of Western Australia – Swan – 1:100 000 vegetation series . University of Western Australia Press, Nedlands.

Blatchford T., 1900, The Phillips River mining district: West. Australia Geol. Survey Bull.

Butcher, Rhonda personal communication (2007) in Wetland.edu’s wetland monitoring course (including for collection methodology for aquatic invertebrates), Denmark, Western Australia.

Chapman, A (2007) Wetlands Chapman, A. (2007) The Jerdacuttup – Shaster Wetlands – an assessment of the values, condition and threats. Report for Greenskills Inc. February 2007, unpublished report produced for Greenskills.

Frodsham, T (2007), Jerdacuttup and Shaster Lakes Wetlands Management Plan, unpublished report produced for South Coast NRM

Hickman, E. & Sanders A. (2002) Oldfield catchment biological survey. Oldfield Landcare Group, Munglinup.

S.A Halse, M.N Lyons, A.M Pinder and R.J Shiel(2004). ‘Biodiversity Patterns and their Conservation in Wetlands of the Western Australian Wheatbelt’ from Records of the Western Australian Museum, Supplement No. 67: 337-364

Hodgkin, E.P. & Clarke, R. (1989) Estuaries of the Shire of Esperance – Stokes Inlet, Oldfield Estuary and ten others. Estuarine Studies Series No. 5, Environmental Proctection Authority, Perth.

Jaensch, R.P., Vervest, R.M. & Hewish, M.J. (1988) Waterbirds in Nature Reserves of South- western Australia 1981-1985: reserve accounts . Report No. 30, Royal Australasian Ornithologists Union, Canning Bridge WA.

Jones , Andrew, personal communication ., 10/12/07

Montgomery A,. , 1903, The Phillips River Goldfield: West Australia Dept. Mines Rept., p. 3-68.

Storr, G.M. (1991) Birds of the South-West Division of Western Australia. Records of the Western Australian Museum Supplement No. 35.

Woodward H, . P., 1894, A report on the country between Broomehill and the Dundas Hills, and the mines in that neighbourhood: West. Australia Dept. Mines Ad Interim Rept. 1894, p. 14.

Appendices

Appendix 1- THE DUNNS LAKE SUITE OF WETLANDS – AN ASSESSMENT OF VALUES, CONDITION AND THREATS, by Andy Chapman

With further Appendices added:

Appendices Appendix A- Birds recorded at Dunn’s Lake Suite of Wetlands Appendix B- Water quality measurements for Dunns Lake suite of Wetlands Appendix C – Variation of parameters with depth at Dunns Lake, 7 November, 2007.

1.0 INTRODUCTION

1.1 Preamble

On the south coast of Western Australia, as elsewhere, there is increasing recognition of the value of wetlands that includes their ecological service function, amenity and scenic value, conservation value particularly for waterbirds and recreational use. In addition there is recognition that some catchment activities can be inimical to these values. The ecological service functions of wetlands include flood mitigation, nutrient flux and to serve as a ‘window’ on ground water processes. In this sense they are similar to the miners’ canary – serving as an indicator of approaching conditions which may be deleterious beyond the wetlands themselves.

1.2 Location, land tenure and land use

The Dunns Lake suite of wetlands are located on the mid south coast of Western Australia between 3 km NE and 6 kmm ENE of the town of Hopetoun. Figure 1. The suite consists of three separate sub systems; the distinctive and well known Dunns Lake and a companion wetland 500 m NE, a small constellation of wetlands 1.5 km ESE of Dunns Lake – the ‘triple swamps’ and two wetlands 4.5 km ENE of Dunns Lake – the ‘twin swamps’ see Figure 1 and Table 4 for AMG coordinates.

The regional setting for these wetlands is a small wedge shaped piece of crown reserves of c. 1 000 ha with the town of Hopetoun to the west, agricultural land and a recent subdivision to the north and the Southern Ocean to the south. Dunns Lake is within reserve number 31920 of 90 ha for ‘water supply’, the remaining wetlands are in reserve number 28438 of 351 ha for ‘recreation’ that is unvested and is proposed as a nature reserve in DEC’s South Coast Regional Plan (CALM 1992).

1.3 Climate

The climate of the area is classified as ‘dry mediterranean’ by Bagnouls & Gaussen (1957), cited by Beard (1981). ‘Mediterranean’ recognises that on average most rainfall is in winter, ‘dry’ indicates that there are 5-6 dry months per year according to this system. This classification fails to recognise that the most intensive rainfall events are usually in summer from either decaying tropical cyclones or complex upper atmosphere interactions between cold fronts and moist tropical air. It is these that usually cause vigorous river flow, flooding and fill wetlands. Evaporation data are few for the south coast. Hodgkin (1997) estimated that for Culham Inlet, 10 km west of Hopetoun, the evaporation is about 1 100 mm for the six months November-April.

Wetlands everywhere are influenced by previous rainfall and this applies particularly to areas of variable and unpredictable rainfall such as the Ravensthorpe Shire where the coefficient of variability of rainfall is higher than anywhere else on the south coast between Cape Leeuwin and Esperance (Chapman 2003). Rainfall data have been collected at Hopetoun since 1901 where the annual mean and median rainfall are 504.3 and 502.8 mm respectively. The highest and lowest annual rainfall figures are 736.8 and 281.8 mm for 1971 and 2002 respectively. The highest monthly rainfall was 329.9 mm in May 1988, more than 250 mm fell in less than 24 hours. Rainfall events of this intensity have an enormous influence on rivers and wetlands with the capacity to determine sediment transport, erosion and vegetative changes.

Five less than average rainfall years preceded this assessment as indicated by Table 1.

Table 1. Hopetoun annual rainfall 2002 – 2006 with percentage departure from mean

Year 2002 2003 2004 2005 2006

Annual rainfall (mm) 281.8 493.2 477.8 466.9 403.8 Departure from mean (%) -44.1 -2.2 -5.2 -7.4 -19.9

Over 4-5 January 2007 an intensive rainfall event caused by the convergence of ex tropical cyclone ‘Isobel’ and a mid level trough bought local flooding, road damage and significant stock losses. Over the period 3-6 January rainfall at the following centres was; Hopetoun 106.0 mm, Ravensthorpe 151.4 mm, Cheadanup 204.4 mm and Esperance 191.6 mm. In spite of very heavy rains in January and April most months in 2007 were below average in rainfall as data in Table 2 indicate. However to the end of October 534.6 mm were received compared to the expectation (summed means January-October) of 444.8 mm. Thus 2007 was an above average rainfall year.

Table 2. Monthly rainfall for Hopetoun January – October 2007 with monthly means

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Rain 115.0 16.2 14.6 137.8 32.8 65.4 35.2 33.8 26.8 57.0 fall (mm) Mean 20.7 21.0 28.4 39.3 63.6 62.4 62.2 58.9 53.0 38.9

1.4 Geology and Hydrology

The wetlands themselves occupy Quarternary lacustrine deposits (Ql) of clay and silt that are embedded in two different Quarternary sequences. Dunns Lake and

2 ‘Companion swamp’ lie between consolidated coastal deposits of calcarenite (Qt) to the south and coastal dune sand (Qct) to the north that is a re-worked product of Qt. ‘triple and twin swamps’ are similarly lacustrine deposits; they are at the western extremity of an extensive east-west belt some 5 km long that is embedded in consolidated coastal deposits. These interpretations are from Witt (1997).

The hydrological mapping of Johnson (1998) indicates the depth to groundwater here is 5-15 m (though it is certainly much less in the immediate vicinity of these wetlands). The salinity of groundwater is 7 000 – 14 000 mg/l. The approximate EC equivalent to this range is 12.7 –25.4 mS/cm.

1.5 Previous studies

Previous studies include the general assessment of wetlands between Hopetoun and Munglinup (Chapman 2007) and the subsequent management report (Frodsham 2007). Invertebrates and water quality data were collected at Dunns Lake as part of a biodiversity survey of agricultural lands under the salinity action plan (see Keighery et al. 2004).

1.6 Definitions and classification

A recent definition of a wetland in the Australian context is:

A wetland is any area of temporary or permanently waterlogged or inundated land, natural or artificial, with water that is standing or running, ranging from fresh to saline, and where inundation by water influences the biota and ecological processes occurring at any time. From Boulton & Brock (1999).

The Ramsar convention provides a classification of wetlands based on whether they are marine/ coastal, inland or artificial with each of these categories sub-divided on vegetative or permanence criteria. The classification was adopted by ANCA (1996) and is used in this assessment. The following classifications were recognised as being applicable to these wetlands:

• B8 – Seasonal/intermittent saline lakes • B14 – Freshwater swamp forest, seasonally flooded forest, wooded swamps on inorganic soils

In addition to this descriptive classification wetlands are categorised by their relationship to ground water. They may be either perched i.e. independent of ground water, recharging from or discharging to ground water or a combination of these (John Simons, personal communication )

The term ‘samphire’ is used as a collective term for unidentified chenopods of the genera Halosarcia and Sarcocornia. Table 3 indicates salinity criteria from George et al. (1996) except that ‘hypersaline’ was not defined, that are used in this assessment.

3 Salinity and electrical conductivity (EC) are not used as equivalent terms, rather EC being readily measurable is used as an approximate surrogate for salinity.

Common names are only given for weeds and fish. Common and scientific names for birds are in Appendix I.

Table 3 Salinity criteria used in assessment

Salinity Total Soluble Salts Approximate Electrical Conductivity equivalent (mg/l) (mS/cm)

Fresh <500 <0.9 Marginal 500-1 500 0.9-2.7 Brackish 1 500-5 000 2.7-9.0 Saline 5 000-35 000 9.0-63.0 Hypersaline >35 000 >63.0

1.7 Purpose of present assessment The purpose of the present assessment is to obtain further data as to the values, condition and threats to some wetlands previously assessed. Of these the Dunns Lake suite is considered most at risk due to their proximity to agricultural land, land subdivision and housing with population increase in and around Hopetoun.

2.0 METHODS

Field work was conducted over four days in November 2007. At each wetland the following data were collected: 2.1 Nature and condition of the littoral vegetation with particular emphasis on manifestations of degradation due to salinisation/waterlogging and weed invasion. 2.2 Bird use of both the littoral vegetation and the wetland habitats. 2.3 Water quality parameters electrical conductivity, pH, dissolved oxygen concentration, and temperature were measured with a WTW Multiline P4 instrument. At Dunns Lake the variation of these parameters with depth was measured from a kayak. A water sample from each wetland was analysed for total nitrogen and total phosphorus by the Centre for Excellence in Natural Resource Management in Albany. 2.4 For Dunns Lake and the adjacent ‘companion swamp’ the drainage into the wetlands was followed up by walking to examine its origin and factors affecting its quality and quantity. 2.5 An aerial flight on 6 November enabled photography, appraisal of the wetlands and some factors affecting their drainage.

3.0 RESULTS

4 3.1 Description of wetlands

3.1.1 Dunns Lake and ‘Companion Swamp”

Dunns Lake has maximum dimensions of 300 x 150 m with an area of c. 2.5 ha. Wetland classification B8, B14 (see section 1.6). As most of the wetland is an open water surface it is more appropriately described as a lake than a swamp. This also serves to emphasise its distinctive nature compared to other local wetlands. The inner littoral vegetation is mature Meleleuca cuticularis woodland to 8 m in a zone c. 25 m wide approximately most of which was in water at the time of this assessment. Beyond the water understore y species include Gastrolobium bilobum, Acacia subcaerulea, A. cyclops, A. crassiuscula to 2-3 m with Carpobrotus virescens and Threlkeldia diffusa groundcover. The outer littoral zone has Eucalyptus occidentalis to c. 15 m that overlaps Meleleuca cuticularis ; understorey species are Labichea lanceolata, Spyridium globulosum, Rhagodia preissii, Dianella revoluta and Billardieria fusiformis . There are noticeable and very recent deaths of Gastrolobium bilobum, Acacia crassiuscula, A. cyclops, A. rostellifera, A. browniana var. browniana and Kennedia nigricans at the inner-outer littoral zone vegetation interface. The cause of death in unknown but prolonged high water levels and increased residence time of water in soil i.e. waterlogging is inferred. Paperbark deaths are abundant, not recent and pronounced here (photo 1) and there is very little regeneration. A small group of eight immature plants 1.7 – 2.2 m tall were the only ones seen, of these two were recently killed (photo 2). There has been past paperbark fence post cutting.

Since 1996 depth of Dunns Swamp has varied from c. 2.0 m during July 2000 when EC was 7.01 mS/cm to c. 0.2 m during January 1996 when EC was 93.7 mS/cm. The highest EC value of 143.5 was during December 2003 when depth was c. 0.4 m. At the time of the present assessment water depth was c. 2.0 m at the centre. Observations of aerial roots on Melaleuca cuticularis at c. 1.6 m above present water level suggest that water levels to 3.6 m have been present in the past. Observations of the nature of the littoral vegetation indicate that at 2.0 m depth the lake is ‘full’ in the sense that any increase would inundate vegetation that would not normally be considered littoral.

Weeds present were bridal creeper, African boxthorn ( Lycium ferocissimum ), Scotch thistle ( Cardus pycnocephalus ), blackberry nightshade ( Solanum nigrum ), Jersey cudweed ( Pseudognaphalium luteoalbum ), pimpernel ( Anagallis sp.) and fleabane (Conzya sp.).

‘Companion swamp’ has an area of c.2.0 ha, it was formerly a live paperbark swamp that would have been classified B14 on the above criteria. Formerly Melaleuca cuticularis and Eucalyptus occidentalis occupied the entire wetland area. All of these are now dead (photo 3 ). To the west and north the surrounding vegetation is influenced by the poorly defined drainage channel; it is dominated by Melaleuca cuticularis and M. brevifolia to 3 m with occasional dead Eucalyptus occidentalis (mallee form) over samphire, Sarcocornia quinqueflora and sedges. Darwinia vestita are present on low sandy ridges. At the east end there is some Melaleuca cuticularis regeneration to 1.5 m. To the east and south the wetland is confined by a subdued sand dune with typical sandplain vegetation including Nuytsia floribunda, Eucalyptus

5 pleurocarpa, Acacia rostellifera, Lambertia inermis, Adenanthos cuneatus, Melaleuca pulchella, M. thymoides, Hakea corymbosa over Lomandra effusa and Banksia repens. The subdued dune to the south of this wetlands prevents it draining through into Dunns Lake. At the time of assessment depth ranged from 25-50 cm.

Drainage into Dunns Lake and ‘companion swamp’

These two wetlands exhibit the effects of extensive alteration to their natural drainage pattern due to clearing for agriculture, road, railway, airstrip and fenceline construction. Prior to these activities the drainage into these wetlands was from the north west and north through subtle channels into Dunns lake and ‘Companion swamp’ respectively. Presently (and previously) it is unlikely that there was coordinated drainage from either into the other as they are separated by a subdued sand dune. There have been two alterations to the natural drainage into these wetlands:

• Drainage from a large salt scald on farming land to the north (photo 4) has been captured by a north – south fenceline and the embankment of the former Ravensthorpe – Hopetoun railway and diverted to a culvert under Dunn Swamp Road. • Drainage from the Ravensthorpe – Hopetoun Road, paddocks to the west of the road and the Hopetoun airstrip has followed a natural but subtle drainage line from the north west and been impounded by the railway and Dunns Swamp Road embankments. There have been extensive Melaleuca brevifolia deaths due to waterlogging here.

Saline water from both these sources is combined at the culverts under Dunns Swamp Road and then diverted by a fenceline and track running almost due east. Thus the natural drainage into Dunns Lake has been partially captured and diverted into ‘companion swamp’ that has become a sacrificial wetland partially protecting Dunns Lake from the effects of altered drainage. This is perhaps evidenced by the very divergent salinities of the two wetlands: 11.65 cf. 46.8 mS/cm (see also Table 4) but noting that greater rate of concentration at ‘companion swamp’ due to its lesser volume will also be a factor here.

3.1. 2 ‘Triple swamps’

The ‘Triple swamps’ consist of three separate wetlands the largest of which is triangular with a north – south baseline and apex pointing due west and an area of c. 1.5 ha. Two smaller, approximately circular wetlands, one <1 ha and the other only 20 –30 m in diameter, are due east between the triangular wetland and the rehabilitated quarry area. The two larger appear to have been former healthy wooded swamps with mature Melaleuca cuticularis and Eucalyptus occidentalis trees. Both were formerly B14 ‘wooded swamps’ (see section 1.6). At the triangular wetland all internal trees are now dead (photo 5), at the larger circular wetland the trees are partially dead (photo 6) and the smaller circular wetland remains in good condition (photo 7). The littoral vegetation for all three consists of Eucalyptus occidentalis to 9 m and Melaleuca cuticularis to 5m which often has Cassytha sp. over it. Understorey species are Acacia rostellifera, Spyridium glaucum, Darwinia vestita over Rhagodia preissii, Gahnia trifida and samphire. There are occasional occurrences of Baumea articulata

6 indicating perhaps soakage of fresher water. The wetlands are confined to the west by low dunes with Eucalyptus angulosa and Melaleuca pentagona and to the east by a low ridge of limestone that has been quarried for road making material.

There is some Melaleuca cuticularis regeneration 1.5 – 4.0 m on the outer south side of the triangular wetland. Weeds were not observed here, fleabane and long storksbill are occasionally present surrounding the larger circular wetland which also had extensive samphire deaths presumably due to recent inundation. Depth was not accurately measured due to their inaccessibility; the triangular wetland was deeper than the larger circular one and the small circular wetland was dry.

Drainage and hydrology of ‘Triple swamps’

The hydrology and relationship of these swamps to the water table is beyond the scope and expertise of this assessment. However field observations allow some provisional conclusions. With the possible exception of the triangular swamp that may have subtle drainage entering from the north there is no coordinated drainage into these swamps and they do not appear to flow into each other. This raises the possibility that water levels are maintained by ground water inflow. What is apparent is that water residence time, if determined by depth, varies between them with triangular swamp>larger>smaller circular swamps. This correlates with degree of degradation (see photo sequence #,5,6,7) and raises the possibility that rising ground water and waterlogging are an ongoing threat to these wetlands.

3.1.3 ‘Twin swamps’

Two smaller, dry swamps were assessed. Although they are quite discrete entities on aerial photography and on the ground they are mapped on the ‘Hopetoun’ 1:50 000 map as part of a much larger area of ‘perennial swamp’ Each has maximum dimensions of c. 200x150 m and an area of c. 3 ha. Both are classified B8 (see section 1.6). Both have very similar vegetation and old nests of either cormorants or egrets from a previous flood event (photo 8), they are more abundant at the eastern most swamp. Both have abundant and pronounced paperbark deaths though there is inner regeneration to 1.5 m at both. In the few places where paperbarks have not died they are to 5 m with understorey species Acacia cyclops, A. pulchella, Rhagodia preissii, Westringia rigida and un-identified sedges. A low sandy ridge with Eucalyptus occidentalis to c. 5 m growing in the straggly ‘coastal’ habit with Labichea lanceolata and Spyridium globulosum separates the swamps.

There is no recognisable coordinated drainage into these swamps. There has been past paperbark fence post cutting. Following heavy rain in January 2007 these wetlands held c. 15 cm of water with EC of 10.95 mS/cm but were dry at the time of this assessment.

A low limestone ridge vegetated with Eucalyptus platypus var. heterophylla, E. falcata, E. ?micranthera and E. angulosa confines these swamps to the south.

3.2 Water quality and characteristics

7 Although it varied considerably the salinity of all these wetlands’ waters is in the saline range (see Tables 3 & 4). There can be no doubt that salinity in Dunns Lake is increasing. Evidence for this is that in historical time (1905-1935) water from Dunns Lake was used for steam locomotives. This water could no longer be used for this purpose. Presently, even following flooding, the water here does not revert to fresh; ten days following the January 2007 flood the EC here was 3.33 mS/cm which is brackish. Additionally, vegetative change from melaleuca shrubland to samphire marsh in the vicinity of ‘companion swamp’ is indicative of both increasing salinity and residence time of ground water.

Waters were consistently alkaline and the range (7.56-9.19) is very close to that recorded in the previous assessment [see Table 3 (in Chapman 2007)]. The usual explanation for alkalinity of local waters is their passage through sedimentary rocks that capture hydrogen ions to form bicarbonate.

Dissolved oxygen levels were high, due almost certainly to high levels of photosynthetic activity of both aquatic algae and flowering plants in situations of intense sunlight and little shading of water. This was indicated at one of the ‘triple swamps’ where the only one with abundant Ruppia megacarpa had dissolved oxygen levels twice all the rest (see Table 4).

The situation indicated in Figures 2a & 2b i.e. salinity, dissolved oxygen and temperature not varying with depth indicates complete mixing of the water column at the time of assessment. The only noticeable diurnal change is that the surface waters are heated by 5 0 C to 0.5 m between 8.30 am and 6.30 pm. There was a very slight decline in dissolved oxygen level in the surface water (to 25 cm) between 8.30 am and 6.30 pm that may have been due to the temperature increase.

Data on total nitrogen and total phosphorus in all wetlands (see Table 4) indicate very high levels that exceed upper recommended limits (see Discussion).

3.3 Bird use of wetlands

This assessment recorded 56 species of birds including 19 species of waterbird that use these wetlands and their littoral vegetation (Appendix I). In spite of early signs of degradation the littoral vegetation of these wetlands provide valuable habitat that is not locally available elsewhere for a wide range of birds other than waterbirds.

Waterbird use was not extensive; part of the reason for this is that being of small size with little or no exposed open shoreline and with high water levels these wetlands do not provide habitat for a wide range of wading shorebirds including trans equatorial migrants. Waterbird breeding was limited to only one species, black swan, and evidence for this was limited to two recently used nests (see Discussion).

3.4 Fish use of wetlands

On present knowledge only one fish Swan River goby, ( Pseudogobious olorum ) is known for these wetlands. It was recorded at Dunns Lake, the drain flowing into ‘companion swamp’ and in the triangular swamp at ‘triple swamp’. Juveniles were present indicating recent spawning at all sites.

Swan River goby is widespread and abundant in coastal rivers and swamps in the south-west from Murchison River to Thomas River. It is the most resilient of a small suite of four species that inhabit the variable and unpredictable fish habitats of south- east coastal rivers and wetlands. It can withstand higher salinities and temperatures and shallower water than other sympatric species (unpublished data). It is most unlikely that the other members of the suite i.e. black bream ( Acanthopagrus butcheri ), spotted minnow ( Galaxias maculatus ) and western hardyhead (Leptatherina wallacei ) will be recorded from these wetlands as they have different feeding requirements and physiological tolerances.

4.0 DISCUSSION

4.1 Condition of wetlands and threatening processes

The data gathered in this assessment indicate that some of these wetlands have already been changed, and may further be threatened by land use changes in their immediate vicinity. Dunns Lake and ‘companion swamp’ are certainly subject to altered drainage, possibly rising saline ground water and severe weed invasion in the case of the former. ‘Triple swamps’ are subject to rising saline ground water each with gradational attrition determined by residence time of water and/or saturated soil conditions. ‘Twin Swamps’ although exhibiting a degree of Melaleuca cuticularis deaths, appear at present to be functioning with a wetting/drying cycle similar to their presumed original cycle. Evidence for this is that although they retained water following the January 2007 flood, presently they are quite dry.

Interpretation of regrowth, morbidity and deaths of Melaleuca cuticularis is likely to be instrumental in managing these wetlands. For example, if Melaleuca cuticularis regrowth is sometimes inside as well as outside the previous littoral zone the wetland is probably functioning in its original homeostatic mode. If regrowth is only outside the littoral zone or absent the wetland is likely to be subject to waterlogging beyond the duration of its capacity to withstand it. Additionally the role of evapotranspiration of Melaleuca cuticularis in maintaining wetlands’ homeostasis would be worthy of investigation. In particular whether their death causes a reduction of evapotranspiration sufficient to initiate a positive feedback loop whereby increased water residence time increases littoral vegetative deaths that extend centripetally outwards.

In spite of the recognition that these threatening processes are affecting these wetlands it is important to recognise that between them they still function to provide a range of valuable habitats particularly for waterbirds. For example, at the time of this assessment two different species, greenshank and black-fronted dotterel recorded on ‘companion swamp’ were not present on Dunns Lake. This was because greater water levels in the lake had inundated the exposed mud flats required by these birds. Similarly, although black swans were recorded on the lake they will neither feed nor nest here because the water is too deep.

The challenge for management is to acknowledge these threatening processes, identify their causes and if possible mitigate their effects so that in time all these wetlands do not all revert to a similar state of expanding hypersaline lakes without

9 any living vegetation. Similarly, presently low Melaleuca spp. shrubland areas north of these wetlands in the Barrens subdivision are likely to revert to samphire marshes if ground water continues to rise. Evidence that this is already happening is water in a dam on Pardalote Parade, presumably for fire fighting, had EC of 27 mS/cm (noting that seawater has 52 mS/cm). Management of this situation will require a better understanding than we have at present of the effects of agricultural clearing and subdivision development on altered drainage and ground water processes, particularly in flow and out flow to wetland basins.

4.2 Water quality and characteristics

The data gained in this assessment are consistent with data from the previous assessment and what little data is available for other south coast wetlands, i.e. that wetland waters have very variable salinity which is increasing as is its residence time. The salinity increase is likely to be at the lower end of the salinity range i.e. wetlands are no longer reverting to fresh following intense rainfall events and flooding. The increased residence time of water is likely to be more inimical to littoral vegetation than salinity per se .

The waters of these wetlands are well oxygenated, and alkaline. This too is consistent with what little data there are for other south coast wetlands. The complete mixing of the water column at Dunns Lake is typical for lakes in southern Australia at the end of winter; these lakes are described as warm monomictic i.e. never freezing and mixing once a year (Boulton & Brock 1999). This is due to strong winds and low temperatures during cool months of the year. At the end of summer a layer of warmed water could be expected to lie over cold, deeper water with an abrupt temperature change between layers.

Total nitrogen and total phosphorus levels ranged from 2.11 – 4.29 mg/l and 0.04 – 0.31 mg/l respectively that are well in excess of the upper recommended levels of 0.75 and 0.1 mg/l respectively (EPA data in George et al. 1996). However these upper limits are for running water and may not be relevant to the wetlands. Local rivers for example consistently record much lower levels, which are often only slightly higher than recommended (unpublished data). Present levels in Dunns Lake have declined to almost exactly 50% of their level prior to flooding rain in January 2007. A more sophisticated analysis of the different components of total nitrogen and total phosphorus would be required to better understand this phenomenon.

4.3 Bird use

Data from this and other assessments of local wetlands and rivers indicate convincingly that the littoral and riparian vegetation they support provide habitat for a wide range of birds other than waterbirds and make a substantial contribution to local biodiversity. This is because the Eucalyptus occidentalis and Melaleuca cuticularis woodlands have a structural and floristic complexity that is not apparent elsewhere on the coastal plain. With further deterioration of littoral vegetation the capacity of the coastal plain to support an abundant and diverse avifauna will inevitably decline.

The 19 species of waterbirds recorded is a relatively small subset of the 49 recorded from wetlands between Hopetoun and Oldfield Estuary in the previous assessment.

10 Reasons for this are the small extent of these wetlands and limited different waterbird habitat, particularly areas of exposed shoreline, that they offer.

Waterbird breeding with only one species recorded was very limited at the time of this assessment. Reasons for this are unclear. Other studies have indicated factors affecting breeding success in Australian wetlands are abundance of aquatic invertebrates, particularly chironomid larvae (Crome 1986) and salinity. Goodsell (1990) found that 90% of broods in south-western Australian wetlands were in wetlands of salinity less than 15 300 mg/l which has an approximate EC equivalent of 27.8 mS/cm. Dunns Lake and one of the ‘triple swamps’ were less saline than this. (Tim, can we make a comment about the relative scarcity of inverts here?)

5.0 ACKNOWLEDGEMENTS

Greenskills (Inc.) proposed and administered this assessment with funding allocated through South Coast Natural Resource Management from the National Action Plan for Salinity and Water Quality, a program of the Natural Heritage Trust. Tim Frodsham of Greenskills accompanied AC on fieldwork and provided valuable discussion and comments on a draft. John Roy piloted the aerial flight.

6.0 REFERENCES

Australian Nature Conservation Agency (1996) A directory of important wetlands in Australia- Second Edition . ANCA, Canberra.

Beard, J.S. (1981) The vegetation survey of Western Australia – Swan – 1:100 000 vegetation series . University of Western Australia Press, Nedlands.

Boulton, A.J. & Brock, M.A. (1999) Australian freshwater ecology: processes and management. Gleneagles Publishing, Glen Osmond, South Australia. 300 pp.

Chapman, A. (2003) Biology of the spotted minnow Galaxias maculatus (Jenyns 1842) (Pisces:Galaxiidae) on the south coast of Western Australia. M Phil thesis, Murdoch University, Perth.

Chapman, A. (2007) The Jerdacuttup – Shaster wetlands: an assessment of values, condition and threats. Unpublished report for Greenskills (Inc.)

Crome, F.H.J. (1986) Australian waterfowl do not necessarily breed on a rising water level. Australian Wildlife Research. 13, 461-480.

Department of Conservation and Land Management (1992) South Coast Region – Regional Management Plan . Management Plan No. 24. CALM, Perth.

Frodsham, T. (2007) Wetland conservation in the Jerdacuttup – Ravensthorpe area, WA: Management of the Lake Shaster and Jerdacuttup wetland suites: assessment and recommendations. Unpublished report to South Coast Natural Resource Management.

11 George, R., Weaver, D. & Terry, J. (1996) Environmental water quality – A guide to sampling and measurement. Miscellaneous Publication No. 16/96, Agriculture Western Australia, Perth.

Goodsell, J.T. (1990) Distribution of waterbird broods relative to wetland salinity and pH in south-western Australia. Australian Wildlife Research , 17 : 219-230.

Hodgkin, E. P. (1997) History and management of Culham Inlet, a coastal salt lake in south-western Australia. Journal of the Royal Society of Western Australia 80 :239-247.

Johnson, S.L. (1998) Hydrology of the Ravensthorpe 1:250 000 sheet: Western Australia. Water and Rivers Commission, Hydrological Map Explanatory Notes Series, Report HM 4.

Keighery, G.J., Halse, S.A., Harvey, M.S. & McKenzie, N.L. (2004) (eds) A biodiversity survey of the Western Australian agricultural zone. Records of the Western Australian Museum Supplement No. 67, Western Australian Museum, Perth, viii+384pp.

Witt, W.K. (1997) Geology of the Ravensthorpe and Cocanarup 1:100 000 sheets: Western Australian Geological Survey. 1:100 000 Geological Series Explanatory Notes.

12 APPENDIX 1 BIRDS RECORDED AT DUNNS LAKE SUITE OF WETLANDS 1 2 3 4

CASUARIIDAE Dromaius novaehollandiae Emu X ANATIDAE Biziura lobata Musk Duck XX Cygnus atratus Black Swan XBB Tadorna tadornoides Australian Shelduck XX Anas gracilis Grey Teal XX Anas castanea Chestnut Teal XX Anas superciliosa Pacific Black Duck X Anas rhynchotis Australasian Shoveler X PODICIPEDIDAE Poliocephalus poliocephalus Hoary-headed Grebe X ANHINGIDAE Anhinga melanogaster Darter X PHALACROCORACIDAE Phalacrocorax varius Pied Cormorant X Phalacrocorax sulcirostris Little Black Cormorant X Phalacrocorax melanoleucos Little Pied Cormorant X ARDEIDAE Ardea novaehollandiae White-faced Heron XX Ardea alba Great Egret X THRESKIORNITHIDAE Threskiornis molucca Australian White Ibis X ACCIPITRIDAE Aquila morphnoides Little Eagle B Elanus caeruleus Black-shouldered Kite X RALLIDAE Fulica atra Eurasian Coot XX SCOLOPACIDAE Tringa nebularia Common Greenshank XXX RECURVIROSTRIDAE Recurvirostra novaehollandiae Red-necked Avocet X CHARADRIIDAE Charadrius melanops Black-fronted Dotterel XX COLUMBIDAE Phaps chalcoptera Common Bronzewing XX PSITTACIDAE Calyptorhynchus latirostris Carnaby's Cockatoo X Cacatua roseicapilla Galah X Glossopsitta porphyrocephala Purple-crowned Lorikeet XX Purpureicephalus spurius Red-capped Parrot XX CUCULIDAE Cacomantis flabelliformis Fan-tailed Cuckoo X Chrysococcyx osculans Black-eared Cuckoo X HALCYONIDAE Dacelo novaeguineae Laughing Kookaburra X Todiramphus sanctus Sacred Kingfisher XX MALURIDAE Malurus splendens Splendid Fairy-wren X PARDALOTIDAE Pardalotus punctatus Spotted Pardalote X ACANTHIZIDAE Sericornis frontalis White-browed Scrubwren X Acanthiza chrysorrhoa Yellow-rumped Thornbill XX MELIPHAGIDAE Anthochaera carunculata Red Wattlebird XXX Anthochaera lunulata Western Little Wattlebird XX Melithreptus brevirostris Brown-headed Honeyeater X Lichmera indistincta Brown Honeyeater XXX Phylidonyris novaehollandiae New Holland Honeyeater XX Phylidonyris melanops Tawny-crowned Honeyeater X PETROICIDAE Eopsaltria australis griseogularis Western Yellow Robin X PACHYCEPHALIDAE Pachycephala pectoralis Golden Whistler XX Colluricincla harmonica Grey Shrike-thrush X DICRURIDAE Myiagra inquieta Restless Flycatcher XX Grallina cyanoleuca Magpie-lark X Rhipidura fuliginosa Grey Fantail XXX Rhipidura leucophrys Willie Wagtail XX CAMPEPHAGIDAE Coracina novaehollandiae Black-faced Cuckoo-shrike XX CRACTICIDAE Cracticus torquatus Grey Butcherbird XXX Strepera versicolor Grey Currawong X CORVIDAE Corvus coronoides Australian Raven X HIRUNDINIDAE Hirundo neoxena Welcome Swallow X Hirundo nigricans Tree Martin X ZOSTEROPIDAE Zosterops lateralis Silvereye XXX

X Species recorded B Breeding record

1 Dunns Lake 2 'Companion Swamp' 3 'Triple Swamp' 4 'Twin Swamp'

Appendix B Water quality measurements for Dunns Lake suite of wetlands.

0 Site AMG Total N Total P EC (mS/cm) Temp ( c) Dissolved O 2 pH (mg/l) (mg/l) (mg/l) Dunns Lake 6242634N, 2.11 0.31 11.55 17.1 6.23 7.56 0237039E ‘Companion 6242851N 3.25 0.06 52.4 23.9 5.12 7.71 swamp’ 0237162E ‘Triple 6242434N 2.76 0.04 29.6 20.9 10.66* 9.19 swamp’ 1 0238013E Triple 6242293N 4.29 0.14 24.7 23.4 6.01 7.88 swamp’ 2 0238255E

Notes AMG is Australian Map Grid. Datum is WGS 84. Zone 51 EC of seawater is 52 mS/cm * abundant Ruppia megacarpa was present only in this swamp

Appendix C - Variation of parameters with depth at Dunns Lake, 7 November, 2007.

20 18 16 14 12 EC (mS/cm 10 TEMP (C) 8 DISS. OXY (mg/l) 6 4 Diss.oxygen/EC/Temp 2 0 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Depth (m)

Figure 2a 8.30 am

15 EC (mS/cm TEMP (C) 10 DISS. OXY (mg/l)

5 Diss.oxygen/EC/Temp

0 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Depth (m)

Figure 2b 6.30pm

Figure 2. Variation of parameters with depth at Dunns Lake 7 November 2007

Appendix 2

Photographic plates

Unless otherwise stated, all photographs were taken by Tim Frodsham

the compiler of this report, on the 7/11/07 to 8/11/07.

Plate 1: Western aspect of the wetland study area. To the right of the main access road to these wetlands is a development area slated for peri-urban/semi-rural blocks. In the background is Culham Inlet and the Fitzgerald River National Park.

Plate 2: Drainage to Dunns Lake from upstream properties in the Hopetoun area. The very low gradient is indicated by the dispersed nature of sheet flow across property boundaries.

Plate 3: Samphire colonized flats on the north side of Dunn Lake and Companion Swamp, indicated low velocity sheet flow of saline water. Photo: Andy Chapman.

Plate 4: Clearing around wetlands in the Hopetoun area has occurred recently on agricultural properties, such as this one just to the east of the study area.

Plate 5: Threats to catchment upstream from wetlands include overgrazing of stock, leading to surface erosion, as can be seen just beginning here.

Plate 6: One of many holes in a karstic (layered limestone cavity) sinkhole system outside of Hopetoun, just south of golf course. Coastal limestone geology of the area has frequent numbers of these.

Plate 7: ‘Companion Swamp’ is a newly formed wetland, thought to be caused by flooding adjacent to the access road building to the north, and upstream in the catchment to this area. Notable is the drier periphery of sandy clay.

Plate 8: Culham Inlet in the foreground forms the western boundary of the Hopetoun wetland areas, which lie to the north and east of the Hopetoun urban area, and its rapidly expanding periphery (top right). Extensive clearing on the Jerdacuttup plain is most evident in the background.

Plate 9: Dunns Lake. Vehicle access is from Dunns Swamp Road. It has a healthy vegetation buffer, but littoral (fringing) vegetation is stressed. It is the largest and most ecologically and historically significant wetland in the Hopetoun area.

Plate 10: Flooding of Dunns Lake for extended periods has stressed newly recruited paperbarks ( M. cuticularis ).

Plate 11: Companion Swamp, with low dune to south. Invertebrate collection was done here.

Plate 12: Twin Swamp 1. The largest of the triple swamp system. There is a large scale mortality of Yate (E. occidentalis ) and Paperbark (M. cuticularis) here is thought to have been caused by anoxia from overflooding for extended periods.

Plate 13: Large tree mortality also exists around Twin Swamp 2.

Plate 14: Adjacent to both Twin Swamps 1 and 2, there are pockets of newly recruiting paperbarks (M. cuticularis ) on alluvial flats, with taller Yate trees ( E. occidentalis ) in the background. This is a typically representative view of the vegetation complex.

Plate 15: A view of the transect from Dunn’s Road culvert to Companion Swamp. Acid Sulfate soil testing was carried out on this transect.

Plate 16: Real Estate sub-division signage some 1km north of Dunns Lake. The road north is Dunns Swamp Road.

Appendix 3:

Production and monitoring water wells in the Hopetoun region

Courtesy of the Water Corporation

Appendix 4: Maps on wetlands study areas

Map 1: Dunn’s Swamp, Companion Swamp and Triple Swamps Study area Map courtesy of Shared Land Information Platform (SLIP) http://spatial.agric.wa.gov.au/slip/

Companion

Dunn

Triple

Hopetou

Map 2: Dunn’s Swamp, Companion Swamp and Triple Swamps Study area Map courtesy of Shared Land Information Platform (SLIP) http://spatial.agric.wa.gov.au/slip/

Appendix 5 Wetland Macroinvertebrate Field Data Sheets

Wetland: Dunns Lake

GPS: E237203, N6246370

Sampler(s): Tim Frodsham, Andy Chapman Date: 7/11/2007 Time: 11:30 Hydrological Phase (Circle 1): Full Filling Drying Weather/Conditions: Fine, moderate wind, 23 oC Photo:

Habitats included Sweep 1 (location) Sweep 2 (location)

shallow water; Deeper water (>0.4m) 0.1m to 0.3m- shaded

% detritus 70 20 coverage

Emergent vegetation

Submerged Ruppia polycarpa vegetation

Flooded M. cuticularis, E. vegetation occidentalis

Taxa

Ostracoda (seed 2 shrimp)

Zygoptera 1 (damselflies)

Coleoptra 2 Hemiptera (true 1 1 bugs)

Corixidae (water 2 2 boatmen)

Amphibia 1 1

Other Ladybug (1 only) Goby fish (1 only)

Abundance categories: 1 = ,10; 2 = 11-100; 3 = 101-1000; 4 = >1000

Wetland Macroinvertebrate Field Data Sheet

Wetland: Companion Swamps

GPS: E236974, N6242836

Sampler(s): Tim Frodsham, Andy Chapman Date: 7/11/2007 Time: 12:40 Hydrological Phase (Circle 1): Full Filling Drying Weather/Conditions: Fine, light wind, 26 oC Photo:

Habitats Sweep 1 (location) Sweep 2 (location) included

Deeper water Shallower, on shoreline

% detritus 30 30 coverage

Open water

Emergent vegetation

Submerged Ruppia polycarpa Algal mats vegetation

Flooded Halosarcia, M. Halosarcia, M. cuticularis, vegetation cuticularis, E. E. occidentalis occidentalis

Other

Taxa

Gastropoda 1 (snail & limpets) Ostracoda 4 (seed shrimp)

Amphipods 3 (scuds)

Other Crustacea >4

Abundance categories: 1 = ,10; 2 = 11-100; 3 = 101-1000; 4 = >1000

Wetland Macroinvertebrate Field Data Sheet

Wetland: Twin Swamp 2

GPS: E237860, N6242271

Sampler(s): Tim Frodsham, Andy Chapman Date: 8/11/2007 Time: 10:30 Hydrological Phase (Circle 1): Full Filling Drying Weather/Conditions: Fine, light wind, 26 oC Photo:

Habitats Sweep 1 (location) Sweep 2 (location) included

shallow water; 0.1m to 0.3m- one sweep only (limited access).

% detritus 10 coverage

Open water

Emergent vegetation

Submerged Ruppia polycarpa vegetation

Flooded Halosarcia, M. vegetation cuticularis, E. occidentalis Other

Taxa

Ostracoda 3 (seed shrimp)

Zygoptera 1 (damselflies)

Coleoptra 1 only (hydrophilidae)

Other Goby fish (1 only)

Abundance categories: 1 = ,10; 2 = 11-100; 3 = 101-1000; 4 = >1000

Aboriginal Heritage Inquiry System Register of Aboriginal Sites

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MGA Zone 51 Northing Easting 6238369 231459 6248490 242396

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N No restriction C Closed I Interim register Accuracy is shown as a code in brackets following the site coordinates.

M Male access only O Open P Permanent register [Reliable] The spatial information recorded in the site file is deemed to be reliable, due to methods of capture.

F Female access V Vulnerable S Stored data [Unreliable] The spatial information recorded in the site file is deemed to be unreliable due to errors of spatial data capture and/or quality of spatial information reported.

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Site ID Status Access Restriction Site Name Site Type Additional Info Informants Coordinates Site No. 19596 I O N Location G Gnamma Hole Water Source *Registered Informant 232672mE names available from 6244015mN DIA. Zone 51 [Reliable]

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