Index of Wetland Condition - Application in Victoria

DEPI’s Index of Wetland Condition (IWC), developed almost 10 years ago, has been used by DEPI and by Catchment Management Authorities (CMAs) for state-wide and regional wetland condition assessments. The IWC measures aspects of a wetland’s soils, water, hydrology, physical form, plants, and the wetland catchment to provide an assessment of its health (condition). The information generated from IWC assessments is used by DEPI and CMAs to identify and assess risks to wetlands, determine management priorities and monitor long-term trends in condition.

The Victoria-wide assessments led by DEPI from 2009-2011 focused on 827 wetlands (approximately 6% of the naturally occurring, non-alpine wetlands in the state). Two groups of wetlands were included: “high-value” – categorised as such using a mixture of those listed under the Ramsar convention and Directory of Important Wetlands in Australia, as well as high-value wetlands identified in the Wimmera region; and “representative” – a selection chosen as representative of the wide range of Victorian wetland types. Assessments found that just over half of each wetland group were in good or excellent condition, while 14% of high-value wetlands and 25% of representative wetlands were in poor or very poor condition. The number of high-value wetlands in good condition was surprising given that this assessment occurred at the end of a period of unprecedented drought. The results may reflect the resilience of these wetlands to drought, the effectiveness of management activities, or both. More representative wetlands were in poor or very poor condition because threats, such as altered hydrology and reduced water quality are more prevalent at those wetlands.

CMAs have used the IWC to gauge wetland health in response to management activities such as environmental watering, and to natural floods. The IWC is also part of a program where private landholders can seek funding from CMAs to improve the condition of wetlands on their property. Several hundred wetlands have been assessed using the IWC since its adoption in such funding programs.

For more information see the IWC website or contact phil.papas@dse.vic.gov.au

The results of DEPI's statewide assessments are available in the following report:

ARI Technical Report 229 - Victoria's wetlands 2009-2011: statewide assessments and condition modelling [PDF File - 2.2 MB]
ARI Technical Report 229 - Victoria's wetlands 2009-2011: statewide assessments and condition modelling (accessible version) [MS Word Document - 6.3 MB]
A short video titled The Scoop! Index of Wetland Condition is available on the DEPI YouTube channel.

The following reports detail the development, design and testing of the Index:

IWC Conceptual Framework and Selection of Measures 2005 [PDF File - 908.0 KB]
IWC Review of Wetland Assessment Methods 2007 [PDF File - 475.8 KB]
IWC Assessment of Wetland Vegetation Update September 2009 [PDF File - 1.3 MB]
IWC Training Information Management and Testing 2009 [PDF File - 2.4 MB]

Conservation and Management of Spring Wetland Vegetation in the Strathbogie Ranges

In a collaborative project between ARI and the Goulburn Broken Catchment Management Authority, an extensive survey of spring wetland vegetation was undertaken in the Strathbogie Ranges in 2008. The aim of the survey was to document and describe these rare plant communities, which are entirely dependent on groundwater. The study found that at least half of the original wetland vegetation in the area had been cleared since European settlement. It also found that at sites where livestock grazing had been excluded, almost all of which occur on private property, there was lower species diversity and a greater dominance of large sedges. In contrast, vegetation which has been continuously grazed was relatively open and species rich. To contribute to more effective wetland management, a follow-up study was initiated in 2010 to identify grazing regimes compatible with conservation and farming.

A grazing experiment was established in three different vegetation types to identify which mix of grazing and non-grazing would best maintain species diversity and prevent one or two species dominating over other less competitive species. The vegetation in fenced plots (ungrazed) was compared to unfenced (grazed) plots the same size, for two years. At four treeless sites, both native and weed species increased in grazed as well as ungrazed plots, most likely as a result of greater than expected growth during unusually wet conditions following years of drought. Higher light availability at these sites in comparison to one other site where the tree canopy was mostly intact, was probably also a factor. At another site, some small herbs and sedges sensitive to trampling showed strong initial recovery after livestock removal. However at all sites, most noticeable was the difference in abundance of large sedges and weeds, which was lower in the grazed plots at the end of the trial regardless of location.

This project is an example of the complex interactions between site history, season and disturbance and illustrates the difficulty of developing management prescriptions at a landscape scale. Indications are that grazing by sheep or cattle can control dominant species but in general, the study found that a rest from grazing during spring and summer may be beneficial in future to maintain small herbs and control highly competitive species, especially in severely disturbed sites.

For more information contact: arn.tolsma@dse.vic.gov.au

The following report is available:

The floristic values of wetlands in the Highlands and Strathbogie Ranges [PDF File - 2.8 MB]

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Cultural Conservation of Freshwater Turtles at Barmah-Millewa Forest

The Yorta Yorta people recognise that the recent drought and insufficient external knowledge about turtle habits have contributed to declining health of populations. This is of particular concern for Yorta Yorta Nation as the Broad-shelled Turtle is an animal totem connected to their creation stories. This species is also listed as threatened in Victoria. The Common Long-necked Turtle (Chelodina longicollis) and the Murray River Turtle (Emydura macquarii) also live in the forest. Three years of surveying have found that all three species respond differently to drought. In particular, the Common Long-necked Turtle was in poor condition and found in overcrowded, retracting water holes. Since the recent floods, the body condition of this species, and the Murray River Turtle, has improved.

For more information contact: katie.howard@dse.vic.gov.au or DEPI Indigenous Facilitator lee.joachim@dse.vic.gov.au

A short video titled Joining forces: Traditional knowledge & science conserving Murray Freshwater Turtles is available on the DEPI YouTube channel.

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Fish Spawning and Recruitment in Barmah-Millewa Forest: responses to natural flows and environmental water

Regulation of water flow along the Murray River has significantly altered the frequency and extent of natural flooding of Barmah-Millewa Forest. This has caused a decline in ecosystem health, which has impacted on various aspects of fish life. Environmental water (water released for ecological purposes) can be used to imitate natural flooding and help rehabilitate the Forest. However, we need to better understand how fish respond to different types of flows. ARI has recently completed a six year research program investigating the effect of varying flows and the use of environmental water, on aspects of fish breeding in the Forest.

The fish community in Barmah-Millewa Forest was sampled over five consecutive years (2003-2007), which were characterised by different timing and magnitudes of flooding, (including an environmental water release of 513 GL in 2005). Fish were also sampled again after a major flood event (late 2010). This study found that the best breeding response occurred after moderate spring and early summer flooding, which was supplemented by the environmental water release. For Murray and Trout Cod the number of young fish (less than a year old) increased, while for Silver and Golden Perch there were greater numbers of eggs and larvae caught. This is a particularly important outcome as these four species have high conservation and recreational significance.

Unexpectedly, the large-scale protracted spring-summer flooding of 2010/11 reduced native fish spawning and recruitment. This was likely due to the creation of hypoxic blackwater (tea stained water that has little oxygen) which arose from a combination of four years of drought and associated leaf litter build up on the floodplain, and floodplain inundation during the summer months. This finding is a timely reminder that flooding does not always deliver short-term benefits for native fish populations. More information on how different species and different life stages respond to flow will better guide future deliveries of environmental water. This research was funded by the Murray-Darling Basin Commission and will be used to help make decisions on the timing and volume of future allocations that will be most beneficial to native fish populations.

For more information contact: scott.raymond@dse.vic.gov.au

The following journal articles are available:

King, A.J., Ward, K.A., O’connor, P., Green, D., Tonkin, Z. and Mahoney, J. (2010) Adaptive management of an environmental watering event to enhance native fish spawning and recruitment. Freshwater Biology 55(1): 17–31

King, A., Tonkin, Z. and Mahoney, J. (2009) Environmental flow enhances native fish spawning and recruitment in the Murray River, Australia. River Research and Applications 25(10): 1205–1218

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Watering Floodplain Wetlands for Native Fish - Murray-Darling Basin

Floodplain wetlands are a major part of lowland river systems and are thought to be important nursery grounds for some fish species. However, there is limited information on the relationships between characteristics of inundation (or watering) of floodplain wetlands and how they impact on various aspects of fish ecology. Such information is particularly important for managers working on systems where the flow has been altered, such as the Murray River, who are trying to rehabilitate wetlands by delivering parcels of environmental water. For example, if the timing of watering occurs outside of fish spawning periods, or during winter months when food production is low, native fish populations may not be able to fully benefit from the influx of water.

A study examining how best to water floodplain wetlands for fish was undertaken between 2007 and 2011, and has increased the understanding of the fine-scale relationships between the application of environmental water (i.e. timing, magnitude, duration, method of delivery, and frequency of delivery), wetland habitat characteristics and the fish community. This has lead to the development of management tools that will contribute to effective application of environmental water to river and floodplain wetland systems.

Key findings and outcomes of the project were:

• that watering increases the total abundance of fish in wetlands, by increasing the abundance of fish in their first year of life
• that timing, duration and volume of watering are critical to optimising fish abundance in wetlands, because they affect how fish move between the river and wetlands, and their ability to spawn and recruit
• the development of a fish-in-wetlands decision support tool (FWDST), which allows managers to compare the likely outcomes of different watering scenarios for three native and one introduced fish, based on the characteristics of watering and wetlands
• the development of monitoring guidelines to be used by managers to assess if watering has been successful
• the establishment of a demonstration wetland where managers can apply the above decision support tool and monitoring protocols, and see how they can be used.

This research was a collaborative effort between ARI and the Murray-Darling Freshwater Research Centre and was funded by the National Water Commission.

For more information contact: john.koehn@dse.vic.gov.au

The following report is available:

ARI Technical Report 189 - Watering floodplain wetlands in the Murray-Darling Basin to benefit native fish: a discussion with managers [PDF File - 2.8 MB]

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Wetland Connectivity via Plant and Animal Movement

This project will help identify which wetlands are connected across the landscape by the dispersal of plants and animals. To do this we need to consider the different ways plants and animals move among wetlands, the distances they can travel, and what factors limit their movement. For example, waterbirds and fish are very mobile, whereas plant seeds and invertebrate eggs rely on wind, water or waterbirds to disperse. The distances plants and animals move also differ greatly. Waterbirds can reach wetlands separated by long distances, whereas frogs move only short distances and probably only access nearby wetlands. In some cases the ability of organisms to move among wetlands has been disrupted by human activities. For instance, the drainage of wetlands for agriculture has increased the distances between wetlands, and the diversion of water from waterways has reduced the occurrence, duration and extent of floods, which are important in the dispersal of plants, fish and invertebrates.

Identifying which wetlands are connected by dispersal will inform management decisions. For example, an understanding of wetland connectivity will help identify sites that have strong connections to each other though dispersal and should be managed collectively, rather than as individual wetlands. Wetland connectivity can also be used to identify sites where restoration activities will have flow on benefits to other wetlands through improved dispersal. This project is being funded by DEPI’s Natural Resources Investment Program.

For more information contact: kaylene.morris@dse.vic.gov.au

The following report is available:

ARI Technical Report 225 - Wetland connectivity, understanding the dispersal of organisms that occur in Victoria's wetlands [PDF File - 899.7 KB]

ARI Technical Report 225 - Wetland connectivity, understanding the dispersal of organisms that occur in Victoria's wetlands (accessible version) [MS Word Document - 2.0 MB]

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