Category Archives: Pollution issues & solutions

Ecological restoration and rehabilitation at Sydney Olympic Park – UPDATE to EMR feature

Jennifer O’Meara and Kerry Darcovich

[Update to EMR feature – O’Meara, Jennifer and Kerry Darcovich (2015) Twelve years on: Ecological restoration and rehabilitation at Sydney Olympic Park, Ecological Management & Restoration, 16:1, 14-28. https://onlinelibrary.wiley.com/doi/10.1111/emr.12150 ]

Keywords: Environmental management, ecological management, threatened species, Habitat management , woodland birds, Green and Golden Bell Frog

Introduction. The 2015 EMR feature described ecological restoration and management works at Sydney Olympic Park, a large urban park containing both remnant and constructed landscapes that underwent significant restoration in preparation for the 2000 Olympic Games. Sydney Olympic Park supports a rich natural environment that includes over 250 native animal species, over 400 native plant species and three endangered ecological communities.  The high ecological values of the Park have resulted in 304 hectares (nearly half of the Park) being zoned under NSW planning legislation for environmental conservation and management.  Key habitats include estuarine and freshwater wetlands, remnant eucalypt forest, saltmarsh meadows and woodland bird habitats.

The Park’s biodiversity is of high conservation significance, and makes a significant contribution to the social and economic values of the Park.  The Park’s natural environments enrich visitor experience, provide a living classroom for environmental education programs, and attract businesses and residents seeking proximity to nature. This project began in 2000 when management transferred from a construction phase after the Sydney Olympic Games to an active management phase and is supported by an extensive long term ecological monitoring program. This update summarises new works and outcomes since 2016.

Further works undertaken. The introduction of new ecological infrastructure for frog habitat targets threatening processes of predation by introduced fish and increasing water availability.  Fish-proof fences have been introduced to wetlands where the predatory fish Gambusia (Gambusia holbrooki) is present in Green and Golden Bell Frog (Litoria aurea) habitat (Fig 1). The fences are placed around ponds or pond clusters and then the pond is dried out and refilled with fish-free water. Constructed of sediment fences 600mm high and embedded in the ground, these fences stretch to a maximum of 200m and have successfully restricted the fish from ponds for more than three years.

Figure 1.  Gambusia fence

In order to reduce the impact of bird predation on tadpoles in key breeding ponds, bird netting secured by wire cables to the ground and supported by hoops has been introduced.  The netting is also used as a response to the sighting of Green and Golden Bell Frog tadpoles in ponds with Sydney Olympic Park staff deploying temporary netting where successful breeding has occurred. Netting is left on the pond until all metamorphs have dispersed from the pond then removed.

Restoration of the water-holding capacity and connectivity of bell frog habitat in the Brickpit and Kronos Hill has been improved with temporary ponds being created with tarps (Fig 2). The aim is twofold – to extend the number of predator-free, drought refuges, important for adult female frogs and metamorphs and to ensure frog corridors maintain connectivity.  More than 10 tarp ponds have been created and have an expected life span of 3-6 years and are very budget friendly. Annual monitoring has shown a remarkable uptake of these ponds by the Green and Golden Bell Frog.

Figure 2.  Tarp pond with netting

Further results to date. The Parks ecological monitoring program is ongoing and now entering the 16th consecutive year for birds, 15th for reptiles and 21 years for the Green and Golden Bell Frog. In 2018-19 the fourth woodland bird survey was completed, a four yearly assessment of the status of woodland birds and vegetation management at Sydney Olympic Park. Fifteen quadrats are surveyed over the spring and autumn seasons to measure bird communities which is then compared to change in vegetation structure. Results show that small birds were strongly, positively correlated with shrub cover, but strongly negatively correlated with tree cover and Noisy Miner (Manorina melanocephala).  Since 2006, Sydney Olympic Park Authority has implemented a habitat modification program aimed at increasing the structural diversity and complexity of key areas of the Park to support woodland birds. The program seeks to build connectivity between key woodland bird habitats with the form of habitat enhancement varying depending on site characteristics. The survey shows that this program is successfully creating suitable habitat for this group of birds.

With the prospect of greater demands by the public to access the Park at all hours (see below), Sydney Olympic Park staff have recently collected baseline light level readings from across the Park to inform decision making.  Data on lux levels and light source was collected from over 160 sites ranging from car parks to mangrove creeks. The main drive of the survey was to collect information on light spill into sensitive habitat areas where darkness is a key ecological feature. The survey led to a review of lighting and identification of where lights could be switched off or timed to decrease light impacts. The findings will also inform future planning for illumination within the Park.

Lessons learned and future directions. Sydney Olympic Park is part of a rapidly densifying area with the 30,000 residents currently located within a 3km radius forecast to increase to approximately 100,000 in ten years. Due to the density of housing, Sydney Olympic Park will be/is already the local park for this community, leading to increasing demand for recreation and access to the Parklands. This presents great opportunities for more people to connect with nature and to incorporate community education and sustainability into Park programs.  A new program known as Park Care has been launched recently and currently rolls out community clean up and revegetation activities.

The flipside of this rapid population increase is increasing risk of disturbance to ecologically sensitive areas which needs to be considered and mitigated carefully as the Park continues to evolve. Ensuring the Park is able to sustainably meet this demand is a focus for management now and into the future. New habitat management plans for ecologically sensitive areas of the Park are being developed to better-guide biodiversity conservation on a precinct level. Ongoing ecological management works, and managing the impacts of human disturbance, will be essential to conserving the ecological values of the Park.

Contact. Jennifer O’Meara, Parklands Ecologist, Sydney Olympic Park Authority, 5 Olympic Boulevard, Sydney Olympic Park 2127 NSW, Australia. Email: Jenny.omeara@sopa.nsw.gov.au

Restoration of Wollongong’s Tom Thumb Lagoon 25 Years On: UPDATE of EMR feature.

 Nicholas Gill

[Update of EMR feature: Gill, Nicholas (2005) Slag, steel and swamp: Perceptions of restoration of an urban coastal saltmarsh. Ecological Management & Restoration, 6:2, 85-93 https://onlinelibrary.wiley.com/doi/10.1111/j.1442-8903.2005.00224.x]

Keywords. coastal wetlands, urban green space, pollution, mangroves, volunteers.

Figure 1. Tom Thumb Lagoon and Greenhouse Park (a) 2008 and (b) 2017. (Source Google Earth)

Introduction. The 2005 feature was drawn from restoration work my students and I became involved in during the early 2000s at Tom Thumb Lagoon (TTL) – an estuarine wetland close to Wollongong’s CBD and adjacent to the Port Kembla industrial area and harbour. By that point Wollongong City Council (WCC), the Bushcare group Friends of Tom Thumb Lagoon (FTTL), industry, Conservation Volunteers Australia (CVA), and many volunteers had been variously working on the site since the early 1990s. After decades of impacts from industrial development, waste disposal, and neglect, this significant restoration effort encompassed removing landfill, reshaping the wetland with channels and shallow benches, revegetation, weeding, and the construction of access and viewing points. By the time we became involved and I wrote the 2005 paper, TTL and the adjacent Greenhouse Park (GHP; Fig 1), were substantially revegetated, aesthetically improved, and the saltmarsh wetlands were seen as ecologically valuable. Participants and stakeholders in the restoration project perceived that substantial progress and improvement had been made. They also perceived, however, that the project suffered from some issues common to such endeavours such as a lack strategic planning and monitoring of ecological outcomes.

Since this time, restoration and other work has continued at TTL and at GHP. The story of what has happened, however, is one of the dynamic and contextual nature of sites such as this. This is true in a biophysical sense of ongoing vegetation change, particularly the spread of Grey Mangrove (Avicenna marina), a native plant previously not occurring on the site but planted for perceived environmental benefits either in the 1990s, or around 2000. This spread (into what was previously saltmarsh and mudflats) arises from past decisions and, while providing benefits, is now potentially causing new problems as well as continuing debates about choices in restoration.  The social context has also been dynamic and influential, as priorities have shifted, as the funding environment has altered, and as the people and groups involved have changed. Finally, Tom Thumb Lagoon remains affected by the legacy of the industrial history of its location. Past waste disposal practices in the absence of regulation have led to pollution problems that have become of greater concern since the early 2000s.

Activities at Tom Thumb Lagoon and Greenhouse Park Today. The wetland area itself is adjacent to a capped waste disposal site that operated from the 1940s until the mid-1970s. This area is known now as Greenhouse Park and is being managed and developed as urban green space with more focus on fostering urban sustainability practices; any restoration work is nested within these foci. TTL and GHP were always associated through overlap between FTTL and GHP staff, and GHP facilities were a base for TTL activities. Today, however, personnel have changed, FTTL no longer exists and its key members are no longer associated with TTL, and TTL/GHP are managed as one site to a greater extent. The result of these factors, and of the achievements already made at TTL, have been a shift towards an emphasis on activities at GHP and a change in TTL activities from active restoration to maintenance. It is now GHP volunteers and associated WCC staff who undertake and oversee work at TTL. At GHP WCC has expended considerable resources in tree planting and expanding a permaculture garden. There is a shelter, outdoor kitchen, and pizza oven for volunteers, WCC and Wollongong firms compost green and food waste, and there are hopes for public, tourism, and event use. Around ten volunteers work at the site weekly. For the GHP staff and volunteers, activities at TTL itself today are largely limited to weeding, picking up litter, and feral animal control. Weeds and litter remain problems, partly due to TTL’s location at the bottom of an urban catchment. In addition, since 2005, frog ponds were installed at the eastern end of TTL for the endangered Green and Golden Bell frog (Litoria aurea), however, it is not clear if the ponds are effective. The non-native Giant Reed (Arundo donax) also remains well established at this end of TTL despite control attempts.

Shifts in support have meant that CVA bowed out of work at TTL/GHP in 2012. Previously their involvement had been via a wetlands program that relied on support from both industry (including Bluescope and NSW Ports, both operating adjacent to TTL) and government programs. Until 2012, in conjunction with WCC, CVA were revegetating the southern slopes of GHP (marked A in Fig. 1) and were removing weeds and litter from the saltmarsh. However, the funding that CVA relied on declined such that CVA was unable to continue at TTL/GHP.

Figure 2.  Eastern end of TTL looking south (a) 2002 and (b) 2019 (Photos Nick Gill)

The Mangroves are Coming. Apart from further revegetation at GHP, the most significant vegetation change at TTL has been the spread of Grey Mangrove. While approval to thin this species has been obtained in the past and some thinning did occur, it has not mitigated their current spread and density. Grey Mangrove spread is clearly seen for the period from 2002 to 2019 in Fig 2 which shows the eastern end of TTL and the southern end of the channel known as Gurungaty Waterway. Aerial photos further reveal changes from 2008-2017 where the largely east-west spread of mangroves along channels in TTL can be seen (marked B in Fig 1). Significant spread can also be seen north-south spread along Gurungaty Waterway over this period (marked C in Fig 1). As the 2005 paper records, not long after Grey Mangrove was planted in the late 20th or early 21st Century, its expansion was  soon causing concern for its consequences for the site’s mudflats, saltmarsh and tidal habitats although it appears to have largely remained confined to the channels and has no doubt generated some environmental benefits. In terms of its consequences on bird habitat, the long observations of local birdwatchers suggest that the expansion of Grey Mangrove has reduced the incidence of waders and shorebirds, particularly Black Winged Stilts (Himantopus himantopus) and also waterfowl and herons. Nonetheless, observers report that Grey  Mangrove colonisation is providing habitat for other birds, such as the Sacred Kingfisher (Todiramphus sanctus), the Nankeen Night-Heron (Nycticorax caledonicus), and the Striated Heron (Butorides striata). Elsewhere across more upland areas of TTL and GHP, the expansion of tree planting across GHP and TTL has seen a shift to birds favouring woodland habitats.

The expansion of Grey Mangrove is also implicated in flood risk, especially for the catchment of Gurungaty Waterway. A 2019 review of the Wollongong City Flood Study, suggests that low elevations and channel infrastructure, combined with sedimentation and flow limitations associated with the now dense mangroves (Fig. 3), have increased the likelihood of flooding in the urban catchment.

Figure 3.  Southern Gurangaty Waterway in (a) 2002 and (b) 2019. Note the steel footbridge on left of each photo. (Photos Nick Gill)

Industrial Legacies. The 2005 paper notes that saltmarsh restoration was an important part of the TTL work and that stakeholders saw the saltmarsh as a significant ecological element of TTL. Since 2004 coastal saltmarsh has been listed as an Endangered Ecological Community in NSW. From 2006, saltmarsh degradation prompted WCC to monitor the saltmarsh and analyse groundwater and soils.  This showed that the degradation was likely associated with ammonia leaching from the tip and causing nitrate pollution, and also with a hydrophilic layer of iron hydroxide in the soil causing waterlogging and contaminant absorption. The possible origins of this layer include past waste disposal practices from metal manufacturing.

These, however, are not the only legacies of past unregulated waste disposal and industrial activity. TTL is now a declared site of ‘significantly contaminated land’ by the NSW EPA. The 2018 declaration notes that site is contaminated by ‘polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons and other mixed contaminants from multiple sources including coal tar and lubricant oils’. At TTL elements of these can be visible as a film on the water surface and are among the substances leaching from GHP. Such substances are carcinogenic and exposure can cause a range of health problems. The presence of these materials in the groundwater has been known since the 1990s but from 2013 WCC began to monitor and map these materials. Monitoring points were installed along the wetlands at base of the old tip. Various remediation options for these contaminants, as well as for the nitrates and iron hydroxide layer, were proposed but action was not taken at this time for various reasons including disruption to the wetland, costs, and uncertainties regarding pollutant interception. As of 2019, the site is subject to a ‘Voluntary Management Proposal’ by WCC which includes the preparation of a remediation action plan by late 2019.

Future Directions. The last fifteen years have seen some aspects of restoration, such as tree planting, proceed and expand. By some measures this is continued progress of the original project. TTL/GHP is now a well-established urban green space with environmental and amenity value. However, concerns from the early 2000s about volunteer succession, the absence of a catchment approach to management, and the need to think more strategically about ecological trade-offs between management options have been realised to some extent. The spread of Grey Mangrove is the clearest example of this. In part, some of this is perhaps inevitable for a site with the history and setting of TTL/GHP; the management context has changed, participants and stakeholders have changed, and difficult legacy issues have assumed greater prominence and cost. Nonetheless, the challenge to manage the site with a clear strategy and goals remains.

Acknowledgements: For assistance with this update, I am indebted to several past and present WCC staff, particularly Mike McKeon. I was also helped by Adam Woods, formerly of CVA, and birdwatchers Penny Potter, Terrill Nordstrom, and David Winterbottom.

Contact. Nicholas Gill, School of Geography and Sustainable Communities Faculty of Social Sciences, University of Wollongong NSW 2522 Australia, Email: ngill@uow.edu.au

East Trinity remediation and rehabilitation after Acid Sulfate Soil contamination, north Queensland

Hanabeth Luke

Key words. Mangroves, estuarine habitat, migratory waders, ecological conversion

Introduction. The East Trinity case study describes the remediation of a severely degraded coastal acid sulfate soil site adjacent to the Cairns township in Queensland, Australia (Fig 1). The project involved extensive collaborative research into geochemistry, soil properties, groundwater and tidal behaviour, terrain modelling and flood modelling by a range of institutions. An innovative strategy known as lime-assisted tidal exchange (LATE) was used to reverse the acidification of the wetland, leading to improved water quality and health of coastal and estuarine ecosystems.

Acid sulfate soils are formed through a natural process that occurred when coastal lowlands were flooded in periods of high sea-level, leading to a slow build-up of metal sulfides such as pyrite. When these soils, normally protected by natural wetlands, are drained for farming or other development and exposed to oxygen, rapid oxidation of the pyrite occurred. This leads to a build-up of acidity in the soil as oxidation processes produce sulfuric acid, releasing toxic metals and noxious gases creating hostile conditions for plant growth. The acid also affects the availability of nutrients in the soil, creating another challenge for plant life. Rainfall events cause the acid, metals and nutrients to drain into waterways, impacting on aquatic ecosystems, infrastructure, fisheries and potentially, human health.

Figure 1. Aerial photo of he location of the East Trinity coastal and acid sulfate soil rehabilitation site (Source: Landsat 1999).

Figure 1. Aerial photo of he location of the East Trinity coastal and acid sulfate soil rehabilitation site (Source: Landsat 1999).

Prior condition and the degradation phase. East Trinity is a 940 ha coastal wetland situated between important estuarine habitats and a World Heritage listed wet tropical rainforest. Prior to clearing for farming, it was a mixture of paperbark woodland, tidal mangrove and salt marsh and had high ecological value for both marine and terrestrial faunal species. The area formed part of the traditional territory of the local Indigenous Mandingalbay Yidinji people.

The site was developed for sugar cane farming in the 1970s, with a bund-wall built to halt tidal inundation of the site. This drainage led to the oxidation of soil materials and a build-up of sulfuric acid in the sediments. A range of CSIRO and other reports showed that this affected 720 ha of the 940ha site. Between 1976 and 2004, it was estimated that at least 72,000 tonnes of sulfuric acid was released from the site, as well as soluble aluminium, iron, heavy metals and arsenic. Water bodies on site were routinely found to have a pH of 3.5 or lower. Aluminium levels were of particular concern, exceeding ANZECC guideline levels by as much as 6,000 times.

The discharge of acid and heavy metals led to death and dieback of vegetation (Figs 2 and 3) and had severe implications for aquatic life. These impacts were of particular concern due to the proximity of the site to the Great Barrier Reef Marine Park, with substantial evidence that acid sulfate soil runoff was discharging into reef receiving waters.

Figure 2a: Aerial view of Firewood Creek area from the 1980s showing extensive grasslands and Melaleuca leucadendra woodlands to the left of the bund wall roadway

Figure 2a: Aerial view of Firewood Creek area from the 1980s showing extensive grasslands and Melaleuca leucadendra woodlands to the left of the bund wall roadway.

Figure 2b: Aerial view of Firewood Creek area in 2013 with extensive flooded areas, Melaleuca woodland die-back and mangrove development.

Figure 2b: Aerial view of Firewood Creek area in 2013 with extensive flooded areas, Melaleuca woodland die-back and mangrove development.

Fig 3. Iron accumulation in oxidised sediments at the East Trinity site.

Fig 3. Iron accumulation in oxidised sediments at the East Trinity site.

Remediation, rehabilitation and restoration phase. The land was purchased by the QLD government in the year 2000, with the ‘Acid Sulfate Soil Remediation Action Plan’ commencing shortly thereafter. This involved a range of engineering solutions to achieved the desired hydrology and apply the lime-assisted tidal exchange remediation strategy, at first on a trial basis. Positive results during the trial period led to the long-term adoption of lime assisted tidal exchange (LATE) at East Trinity.

The LATE remediation strategy. Management strategies for acid sulfate soils are based on the principles of dilution, containment or neutralisation, with each bringing different benefits and challenges. Containment can lead to substantial acid build up and inhibit the movement of aquatic life, whilst the addition of agricultural lime can be costly. The LATE strategy (Fig. 4) was designed to support natural processes by reintroducing tidal flows, encouraging natural systems to restore the wetlands, hence greatly reducing the costs of lime and infrastructure, as well as hands-on management requirements. Flooding the soil stimulated reducing geochemical conditions whilst diluting the acidity. The bicarbonate in seawater provided a large source of alkalinity, whilst the organic matter present provided energy for microbial reactions to take place in the soil, thereby stimulating the in-situ production of alkalinity. Agricultural lime was added to the incoming tide to support the process, and also added to the out-going exit waters to prevent acid-flush into estuarine waters.

Fig 4. The image above shows some of the key parameters improved by the LATE bioremediation strategy.

Fig 4. The image above shows some of the key parameters improved by the LATE bioremediation strategy.

Results of the remediation project. The East Trinity site now has sediments at a spectrum of stages of remediation, with large areas fully remediated. Tidal inundation has ultimately led to a binding-up of heavy metals in the sediments and the neutralisation of acidity to a pH of 6.5, a typical pH for a subtropical estuarine environment. Following six years of gradually increasing tidal inundation, it was found that in-situ microbial and tidal exchange processes accounted for 99% of the change, whilst the addition of agricultural lime contributed less than 1%.

This greatly reduced the release of heavy metals to the estuarine environment and allowed for the re-establishment of mangrove and intertidal ecosystems (Fig. 2b).

Vegetation. Some ecological communities associated with the incursion of seawater and expansion of the tidal zones within the site have reduced while others have expanded. Mangrove communities have expanded and Acrostichum aureum (mangrove fern) fernlands have particularly increased, although some previous fernland transitioned to mangrove. Pasture areas have been largely replaced by Paperbark (Melaleuca leucadendra) shrublands and low woodlands and by the native grass Phragmites (Phragmites karka). The dieback of open forests of Paperbark impacted by the tidal areas continues, with some stands that were healthy in 2008 now in decline. Decline of low Clerodendrum inerme closed vinelands also continues in proximity to the tidal zone, though in other areas this community appears to be recovering.

Birds. A total of 136 species of birds have been observed at East Trinity since the rehabilitation began. Reports suggest that the expansion of mangrove and other higher elevation wetlands associated with the rehabilitation are likely to have benefited a number of bird species, including some internationally important shorebird species listed in agreements with China (CAMBA), Japan (JAMBA) and the Republic of Korea (ROKAMBA). Recently a new wader roosting site has emerged in mangroves on the northern boundary of the East Trinity area and it seems this may be significant in the regional context.

Future directions. The remediation of the East Trinity site has led to the area now having sufficiently high ecological function to be transferred back to Indigneous ownership and management.

The LATE remediation strategy’s regular tidal inundation will remain in place to ensure the acid sulfate soils remain protected from further oxidation; and monitoring and further research will continue into geochemical pathways to avoid degradation re-occurring.

Acknowledgements. The remediation of the East Trinity site and subsequent research has occurred due to the long-term efforts and collaborations between the Queensland Department of Science, Information Technology and Innovation (DSITI), CSIRO, the CRC for Contamination Assessment and Remediation of the Environment (CRC CARE) and Southern Cross University. Figures and data cited in this summary are derived from reports from these organisations available on request.

Contact. Prof Richard Bush, University of Newcastle (University Drive, Callaghan NSW 2308, Australia Tel: +61 (0)2 49215000; Email: richard.bush@newcastle.edu.au) .  Hanabeth Luke is an Associate Lecturer, Southern Cross University (Lismore, NSW 2480, Australia. Tel: +61 (0) 430092071; Email: Hanabeth.luke@scu.edu.au).

Case Study: Restoring the Lost Shellfish Reefs of Port Phillip Bay

Simon Branigan

Key words: shellfish reefs, native flat oyster, blue mussel, ecological restoration, marine ecosystem

Background. Globally, shellfish reefs are the most threatened marine habitat on earth.  Research published by The Nature Conservancy documented that that over 85% of shellfish reefs have been lost from coastal areas worldwide, with 99% of shellfish reefs ‘functionally extinct’ in Australian coastal waters, including within Port Phillip Bay (Shellfish Reefs at Risk Report).

This dramatic loss of shellfish reef habitat in Port Phillip Bay had occurred by the mid to late 20th century, caused by over-harvesting through destructive dredge fishing, further compounded by pollution, predation and disease in later years.

In an Australian first, The Nature Conservancy Australia (TNC) are part of a research partnership that are trialling different approaches to restoring Port Phillip Bay’s lost shellfish reefs (video link).

Shellfish reefs are intertidal or subtidal three-dimensional habitats formed by oysters and/or mussels at high densities. Shellfish reefs can vary in appearance depending on the dominant reef-forming species. There are many common attributes of shellfish reefs including:

  • They provide habitat and refuge for other species including sessile and mobile organisms, supporting high levels of species diversity and unique assemblages;
  • They can accrete dead shell material such that the reef grows in size and mass over time;
  • They provide food for other organisms, either when consumed directly or through the species assemblages they support.
Figure 1. Clumping native Flat Oysters at 9ft Bank in Port Phillip Bay

Figure 1. Clumping native Flat Oysters at 9ft Bank in Port Phillip Bay

Figure 2. Remnant Oyster Reef in Georges Bay, St Helens, Tasmania. (Photo: Chris Gillies)

Figure 2. Remnant Oyster Reef in Georges Bay, St Helens, Tasmania. (Photo: Chris Gillies)

Restoring the Lost Shellfish Reefs of Port Phillip Bay. A three-year trial was established in late March 2015 to investigate the following research questions:

  • Can the oysters simply grow on the bottom or do they need a rubble base?
  • Can oysters be deployed at a young age and survive, or is it more beneficial for a grow-out on aquaculture leases to gain a ‘headstart’?
  • At what densities do we need to deploy mature mussels? (i.e. Can they create mussel beds naturally on the sediment or require substrate?)

 Reference ecosystem. Historical information and relictual evidence shows that the shellfish reefs of Port Phillip Bay were subtidal with the dominant species being native flat oyster (Ostrea angasi) and Blue Mussel (Mytilus (edulis) galloprovincialis). Healthy reference sites for such reefs are very limited in Southern Australia. Within Port Phillip Bay the only site found so far is a dispersed clumping reef called 9ft Bank (Fig 1). A remnant shellfish reef also occurs in Georges Bay, off St Helens in Tasmania (Fig 2). Further research is planned for the Tasmanian site to complete a biological assessment to inform long-term restoration targets and reef design at Port Phillip Bay and other future sites in the region.

Locations of the restoration trials: The intent is to conduct restoration trials in three locations within Port Phillip Bay, although currently works are occurring at only two sites: Wilson Spit (Outer Geelong Harbour) and Margarets Reef (Hobsons Bay) (Fig 3). These are both old shellfish reefs that are largely dead and covered by sediment (Fig 4). The depth range is between 6 to 8 metres depth with Wilson Spit being a silty mud bottom and Margarets Reef sand.

Figure 3. Port Phillip Bay Shellfish Reef Restoration sites.

Figure 3. Port Phillip Bay Shellfish Reef Restoration sites.

Figure 4. Relictual evidence of previous oyster reef at Wilson Spit restoration site. (Photo: Paul Hamer).

Figure 4. Relictual evidence of previous oyster reef at Wilson Spit restoration site. (Photo: Paul Hamer).

Works Undertaken. As Port Phillip Bay is both reef substrate- and recruitment-limited a reconstruction approach (involving rebuilding substrates and reintroducing oysters and mussels) is a necessary starting point for the restoration, with the longer term expectation of natural colonisation.

The trial has involved the deployment of a total of 6 tonnes of limestone marl substrate in a patchwork of 1m x 1m plots at both sites. Native flat oysters are being raised at the Victorian Shellfish Hatchery and their larvae settled on recycled scallop shells (called cultch) (Fig 5). The larvae are then left for a 3-6 month period on an aquaculture lease before being deployed onto the substrate base (Fig 6). To date over 20,000 live oysters have been deployed to seed the reefs. In addition, over 6 tonnes of blue mussel have also been deployed at different densities and in 3 x 3m plots (Fig 7).

Figure 5. Cultch spat growing out at the Bates Point Aquaculture Lease. (Photo: Ben Cleveland)

Figure 5. Cultch spat growing out at the Bates Point Aquaculture Lease. (Photo: Ben Cleveland)

Figure 6. Limestone rubble base with cultch spat. (Photo: Paul Hamer)

Figure 6. Limestone rubble base with cultch spat. (Photo: Paul Hamer)

Figure 7. Deployed mussel bed at Margarets Reef. (Photo: Paul Hamer)

Figure 7. Deployed mussel bed at Margarets Reef. (Photo: Paul Hamer)

 Monitoring Methodology. The University of Melbourne are contracted to lead the monitoring in Stage 1 of the restoration trial. Baseline sampling was conducted of the trial pre-deployment (trial layout is shown in Fig 8) and subsequent monitoring to be carried out 6 months and 12 months after deployment. Monitoring includes measuring:

  • Oyster survival per shell on the various substrate treatments
  • Oyster growth on the various substrate treatments
  • Mussel survival (inner cores only) and mussel growth as well as shell cover and predator density
  • Baseline community sampling (pre-deployment) of mobile fish, cryptic fish, mobile invertebrates, benthic biota and benthic substrate.
Figure 8. An example of the oyster reef experimental design at the Margaret Reef site.

Figure 8. An example of the oyster reef experimental design at the Margaret Reef site.

Lessons Learned and Future Directions. Early monitoring results from both sites show that oyster spat survival is greater if deployed on a rubble base than directly to the seabed, with cultch loss high on sand, due to burial. Oysters grew on average five times as fast on rubble than sand over winter. We conclude from this that elevation is important for both the survival and growth of oysters.

For the mussels the highest density treatment had the highest mortality at both sites, suggesting that the low density treatment improves survival and may be the most cost effective approach.

The most abundant predator was the native Eleven-arm Seastar (Coscinasterias calamaria).

We consider that scale is important in helping to minimise early losses and this hypothesis will be tested in the second stage of the trail. Planning is in place to scale-up the trial to 20 x 20m plots in late 2016, with a mixed-species approach, combining mussels and oysters rather than having separate treatments. Elevation through large and small limestone rubble will also be tested, integrated with recycled shells sourced from restaurants and wholesalers.

Stakeholders and Funding. The Restoring the Lost Shellfish Reefs of Port Phillip Bay Project is a key element of The Nature Conservancy Australia’s Great Southern Seascapes Program and delivered in partnership with the Victorian Government (Fisheries Victoria) and Albert Park Yachting and Angling Club. All partners have contributed funding towards the project and continue to fundraise.

Contact. Simon Branigan, Estuaries Conservation Coordinator, The Nature Conservancy Australia, Suite 2.01, The 60L Green Building, 60 Leicester Street, Carlton, VIC 3053, Australia. Tel: 0409087278. Email: simon.branigan@tnc.org

WATCH FIRST VIDEO: Shellfish reef restoration in Port Phillip Bay

WATCH SECOND VIDEO: Trialling shellfish reef restoration techiques for potential application across Australia

Conserving and restoring biodiversity of the Great Barrier Reef through the Representative Areas Program (RAP)

Key words: Coral reef, no take zones,

The Great Barrier Reef is the world’s largest coral reef ecosystem (344,400 square km) and a World Heritage Area on the north-east coast of Australia. It contains a high diversity of endemic plants, animals and habitats. It is a multiple-use area with different zones in which a wide range of activities and uses are allowed, including tourism, fishing, recreation, traditional use, research, defence, shipping and ports. Components of the ecosystem have been progressively showing symptoms of decline.

TroutBarra3

Coral Trout is one of more than 1625 fish found on the Great Barrier Reef

Existing ecosystems. Coral reefs are like the building blocks of the Great Barrier Reef, and comprise about seven per cent of the ecosystem. The balance is an extraordinary variety of other marine habitats and communities ranging from shallow inshore areas to deep oceanic areas over 250 kilometres offshore and deeper than 1000 metres, along with their associated ecological processes. The abundant biodiversity in the Great Barrier Reef includes:

  • Some 3000 coral reefs built from more than 400 species of hard coral
  • Over one-third of all the world’s soft coral and sea pen species (150 species)
  • Six of the world’s seven species of marine turtle
  • The largest aggregation of nesting green turtles in the world
  • A globally significant population of dugongs
  • An estimated 35,000 square kilometres of seagrass meadows
  • A breeding area for humpback whales and other whale species
  • More than 130 species of sharks and rays
  • More than 2500 species of sponges
  • 3000 species of molluscs
  • 630 species of echinoderms
  • More than 1625 species of fish
  • Spectacular seascapes and landscapes such as Hinchinbrook Island and the Whitsundays
  • 215 species of bird
Crown-of-thorns single injection (C) GBRMPA cropped

Diver injecting Crown of Thorns Starfish

Impacts on the ecosystem. The main threats to the Great Barrier Reef ecosystem are:

  • Climate change leading to ocean acidification, sea temperature rise and sea level rise
  • Catchment run-off of nutrients, pesticides and excessive sediments
  • Coastal development and associated activities such as clearing or modifying wetlands, mangroves and other coastal habitats
  • Overfishing of some predators, incidental catch of species of conservation concern, effects on other discarded species, fishing of unprotected spawning aggregations, and illegal fishing.
4. GBRMPA staff - public consultation(2)

GBRMPA staff meeting to plan and discuss Representative Areas Program (RAP) at Townsville offices

Restoration goals and planning. A primary aim of the Great Barrier Reef Marine Park Authority (GBRMPA) is to increase biodiversity protection, with the added intent of enabling the recovery of areas where impacts had occurred. A strong foundation for this has been achieved through the Representative Areas Program, by developing a representative and comprehensive network of highly protected no-take areas, ensuring they included representative examples of all different habitat types.

The rezoning also provided an opportunity to revise all the zone types to more effectively protect the range of biodiversity.

A further aim was to maximise the benefits and minimise the negative impacts of rezoning on the existing Marine Park users.

These aims were achieved through a comprehensive program of scientific input, community involvement and innovation.

More information on the extensive consultation process is available at http://www.gbrmpa.gov.au.

6. green and yellow zone examples

An example of Green Zones (marine national park) and Yellow Zones  (conservation park)

Monitoring. An independent scientific steering committee with expertise in Great Barrier Reef ecosystems and biophysical processes was convened to define operational principles to guide the development of a comprehensive, adequate and representative network of no-take areas in the Marine Park (Fernandes et al 2005). Science (both biophysical and social science) provided the best available information as a fundamental underpinning for the Representatives Areas Program.

There are currently over 90 monitoring programs operating in the Great Barrier Reef World Heritage Area and adjacent catchment. These programs have largely been designed to address and report on specific issues, location or management.

Reef management. GBRMPA’s 25-year management plan outlines a mix of on-ground work, policies, strategies and engagement. The actions include:

  • increasing compliance focus to ensure zoning rules are followed
  • controlling Crown-of-thorns Starfish (Acanthaster planci) outbreaks
  • ensuring cumulative impacts are considered when assessing development proposals
  • setting clear targets for action and measuring our success
  • monitoring the health of the ecosystem on a Reef-wide scale
  • implementing a Reef Recovery program to restore sites of high environmental value in regional areas — regional action recognises the variability of the Reef over such a large area and the variability of the issues and interests of communities and industries in each area.

Benefits of zoning to date. The benefits reef ecosystem health are already occurring including:

  • More and bigger fish: Larger fish are important to population recovery as they contribute more larvae than smaller fish. James Cook University research shows the network of no-take marine reserves benefits species of coral reef fish targeted by fishers (especially Coral Trout), with not only more fish, but bigger fish in reserves — some zones have around twice as much fish biomass compared to zones open to fishing.
  • Improved fish recruitment: Research in the Keppel Islands suggests increased reproduction by the more abundant, bigger fish in reserves. This not only benefits populations within those reserves, it also produces a ‘spill over’ when larvae are carried by currents to other reefs, including areas open to fishing.
  • Improved resilience: The spillover effects also mean the connectivity between reserve reefs is intact. Spatial analysis shows most reserve reefs are within the dispersal range of other reserve reefs, so they are able to function as a network.
  • Sharks, dugongs and turtles: These species are harder to protect because they are slow growing and slow breeding. They are also highly mobile, moving in and out of protected zones. Despite this, available evidence shows zoning is benefiting these species.
  • Reduced crown-of-thorns starfish outbreaks: Outbreaks of crown-of-thorns starfish appear to be less frequent on reserve reefs than fished reefs. This is particularly important as Crown-of-thorns Starfish have been the greatest cause of coral mortality on the Reef in recent decades.
  • Zoning benefits for seabed habitats: Zoning has improved protection of seabed habitats, with at least 20 per cent of all non-reefal habitat types protected from trawling.

How the project has influenced other projects. In November 2004, the Queensland Government mirrored the new zoning in most of the adjoining waters under its control. As a result, there is complementary zoning in the Queensland and Australian Government managed waters within the Great Barrier Reef World Heritage Area.

The approach taken in the Representative Area Program is recognised as one of the most comprehensive and innovative global advances in the systematic protection and recovery of marine biodiversity and marine conservation in recent decades and has gained widespread national international, and local acknowledgement of the process and outcome as best practice, influencing many other marine conservation efforts.

Stakeholders. As a statutory authority within the Australian Government, the Great Barrier Reef Marine Park Authority is responsible for managing the Marine Park. However, as a World Heritage Area, management of the ecosystem is complex jurisdictionally.

Both the Australian and Queensland governments are involved in managing the waters and islands within the outer boundaries through a range of agencies. GBRMPA works collaboratively with the Queensland Parks and Wildlife Service through the joint Field Management Program to undertake day-to-day management of the Great Barrier Reef, including its 1050 islands, many of which are national parks. The program’s activities include surveying reefs and islands, dealing with environmental risks such as ghost nets and invasive pests, responding to incidents, maintaining visitor facilities, and upholding compliance with Marine Park legislation and the Zoning Plan.

A wide range of stakeholders have an interest in the Great Barrier Reef, including the community, Traditional Owners, a range of industries and government agencies, and researchers. The public, including the one million people who live in the adjacent catchment (around 20 per cent of Queensland’s population), benefit from economic activities. In recent years, the number of tourists carried by commercial operators to the Great Barrier Reef averaged around 1.6 to 2 million visitor days each year (GBRMPA data) with an estimate of an additional 4.9 million private visitors per annum.

Resourcing. The resourcing required for rezoning of the Great Barrier Reef over the five-year period of the RAP (1999–2003) was significant. It became a major activity for the agency for several years, requiring the re-allocation of resources particularly during the most intense periods of public participation. However, the costs of achieving greater protection for the Reef are readily justified when compared to the economic benefits that a healthy Great Barrier Reef generates every year (about AUD$5.6 billion per annum).

Further information: www.gbrmpa.gov.au

Contact: info@gbrmpa.gov.au

All images courtesy Great Barrier Reef Marine Park Authority

 

Audit of water quality problems arising from land use in the Murray-Darling Basin

Key words: water quality, audit, land use, Murray-Darling Basin, Native Fish Strategy

Aims: This is one of a suite of early projects under the Native Fish Strategy (NFS) that sought to scope the issues and information gaps that the NFS would need to address.  Specifically, this project aimed to: :

  • collate data, identify and map regions , landscapes, land uses and industries that are important causes of water quality (WQ) problems in the Basin (e.g. Fig 1)
  • Determine a meaningful scale/accuracy for reporting based on available data and quantitatively report on land use (distributed and point source) contributions to WQ problems on a third order catchment basis.
Figure 1 - this project sought to collate data on land uses and industries which are important causes of water quality problems. Photo courtesy of Arthur Mostead.

Figure 1 – this project sought to collate data on land uses and industries which are important causes of water quality problems. (Photo courtesy of Arthur Mostead.)

Methods: This project was essentially a desktop review and Geographic Information System data atlas formation exercise that included: developing a classification of land uses/management practices in relation to WQ impacts; identifying existing relevant datasets and projects; evaluating available data for relevance and identify gaps; reporting the findings for a pilot catchment (the Broken River/Creek catchment in Victoria). Mapping was available at a range of scales.

There is a wide range of physical, chemical ecotoxicological and ecological parameters that can be used to provide information on WQ, but no single measure of overall WQ. The WQ parameters selected for the study were considered to have direct effects on native fish as well as direct effects on habitat suitability, food sources as well as fish behaviour and ability to migrate and reproduce. Water quality parameters considered of major importance in the study were temperature (cold water); turbidity, dissolved oxygen, and nitrogen/ammonia. Parameters of moderate importance were salinity, pH, toxicants, and pathogens. Land use has known relationships with the nature of WQ changes that occur as a result of that land use (e.g. mining and acid water drainage), and similarly there are known relationships between point source discharges from particular industries and WQ. A matrix of relationships between land use/point source discharges and the nine WQ parameters informed a spatial model that also included a risk assessment of the likelihood and consequence of a critical WQ impact occurring, including the location of high priority native fish sites (species/habitats/refuges). 

The methodology devised for the project was designed to:

  • Facilitate ease of access and use of a complex array of land use and WQ related datasets
  • Display the data so that it can be used by managers responsible for native fish and their habitat
  • Recognise important WQ parameters for native fish in the Basin
  • Provide insight into areas of the Basin under threat from WQ changes with respect to native fish, and
  • provide a predictive yet easy to understand and utilise spatial model.

Findings: The spatial model when applied to the Broken River catchment with land use mapped at ≤1:100,000 scale clearly identified spatial areas that were at risk of WQ impacts, and the level of the risk involved (low, moderate, high extreme). When compared with land use mapped at the 1:250,000 scale, the coarser scale of mapping led to errors in assessment of risk of WQ impacts. Consequently, the spatial model was not recommended to be used for specific catchment investigations where land use was captured at scales >1:100,000. While the limitations of 1:250,00 scale land use capture are acknowledged, analysis using such data may provide useful information to focus further investigations. Consequently the spatial model was applied across the entire Basin at the 1:250,000 scale and indicated the following catchments had the most land use area with high potential to cause water quality impacts that may affect native fish: Gwydir, Namoi, Murray (Hume Dam to SA Border), Murrumbidgee, Loddon, Broken, Goulburn and Campaspe. 

Lessons learned and future directions: The spatial model provided a useful tool for managers to investigate and visualise areas at risk of WQ impacts to native fish. The ability of the model to discriminate such areas at risk at a specific catchment scale declined above scales of 1:100,000 for land use mapping. The lack of detailed information on fish tolerances to various WQ parameters hampers the precision of the model. Similarly the scarcity of spatial data on WQ and the lack of readily available spatial data for fish distribution was a significant issue.

Stakeholders and Funding bodies:  This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contact: Earthtech, +61(7) 3343 3166

Link: http://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/464_execsum_audit_WQproblems_draft.pdf

Bourkes Gorge Spoil Dump #2 Restoration – Kosciuszko National Park

 Elizabeth MacPhee and Gabriel Wilks

Bourkes Gorge Spoil Dump #2 is one of two large spoil dumps created during construction of the Murray 1 Pressure Tunnel between 1962 and 1966 to carry water from the Geehi Reservoir to the Murray 1 Pipelines.  These pipelines deliver water to the Murray 1 Power Station on the western side of Kosciuszko National Park near the township of Khancoban.  At this site during Scheme construction, approximately 300 000 m3 of unconsolidated rock spoil was removed from the tunnel access point on a rail siding and dumped in the steep valley of a tributary creek flowing to Bogong Creek.

 The site prior to rehabilitation. Bourkes Gorge Spoil Dump #2 was one long unstable rock slope devoid of native vegetation with scrap metal, timber and concrete jutting out along erosion scars. It was too steep to stand on, with a slope height of 60m and an angle of approximately 380. The spoil dump was 150m wide across the valley and extended about 250m upstream, blocking the tributary creek. As a result, an 8m washout scar was left in the southern side of the spoil dump with continual erosion down the creek, eroding particularly during peak flows.

Fauna and vegetation surveys were conducted on and in the surrounding forest. Three fauna species listed as vulnerable under the NSW Threatened Species Conservation Act 1995 (TSC Act) were identified in the surrounding forest – the Yellow-bellied Glider Petaurus australis, Gang-gang Cockatoo Callocephalon fimbriatum and the Eastern False Pipistrelle Falsistrellus tasmaniensis. (Schultz, M unpublished). Habitat requirements for nesting and roosting of these species did not occur within the site.  The Spotted Tree Frog Litoria spenceri is listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) and is also listed in the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the TSC Act. This species was known to occur in the vicinity of site, but surveys had recorded a dramatically declining population (Hunter & Gillespie 1999). It was not recorded on or around the site during the fauna survey in 2008. Weeds such as Blackberry (Rubus sp.) and willow (Salix spp.) occurred at the top edge of the site and minimal vegetation was found on the majority of the spoil.

Objectives of the restoration works :

  • Re-shaping the spoil dump to a more stable slope.
  • Constructing an environment that favoured revegetation and habitation of site-indigenous flora and fauna species.
  • Integrating the site into the surrounding tall montane forest
  • Constructing a channel to enable high water flow events to move across the site without scouring or rendering the site unsafe.
  • Slowing high flow events to limit the scour effects on the downstream environment.
  • Safely managing contamination or general construction waste found at the site

Treatments. Works were undertaken from December 2009 to April 2010. Stabilisation works consisted of reshaping the spoil dump and lining 300m of artificial creek line. The resulting land form was planted with 50,000 tubestock in 2010 – 2011 and had specific management practices applied to minimise potential impact on the Spotted Tree Frog.

Plant species used in the revegetation had to be sourced from plants as cuttings, seed or division from the surrounding environment, capable of being commercially propagated due to the number required, and robust enough to withstand the more extreme conditions found on site than in surrounding forest. One rare species Bertya findalyii was found colonising the edge of the site and so was incorporated into the planting list.

Results.

Erosion Control.  The rehabilitation of the Bourkes Gorge #2 spoil dump resulted in 43,300 m3 of rock soil being re-shaped to reduce slope and direct water flow, reducing the potential for surficial erosion and mass slumping. Slope angles were reduced from around 38ْ to between 26ْ and 30ْ  (URS, 2009). Around 560M3 of concrete reinforced with structural synthetic fibre and on site rock was used to form the water channel. In the three years since rehabilitation, there have been two major flood events in the region – October 2010 and March 2012. The Jagungal weather station in Kosciuszko NP recorded 6, 12 and 24 hour duration rainfall intensities exceeding the 100 year Average Recurrence Interval (ARI) intensity. There was no evidence of erosion or slumping at Bourkes Gorge Site following these events.

Revegetation.  Assessment of the vegetation was done two years after planting by Greening Australia Capital Region using BioMetric (http://www.environment.nsw.gov.au/papers/BioMetricOpManualV3-1.pdf).  This monitoring has shown outstanding survival and growth rates – with 35% cover by 19 native species, with virtually nil weed. (Species are listed in Table 1 ).

Lesson learned: Rock spoil in high altitude, steep conditions with no organic matter in a compacted and unstable condition will not naturally revegetate, even if left for a fifty year period.  Applying site appropriate techniques such as re-shaping for stability, allowing for water flow, moving compacted rock to create air pockets and allow water infiltration, and adding the essential ingredients of organic matter, nutrients and plant material can trigger successful site revegetation. Covering the ground with a layer of organic matter such as rice straw ameliorates temperature extremes on site, allowing young seedlings to survive and flourish.

Acknowledgements. Thanks are extended to the restoration team at Kosciuszko National Park, including the many contractors who participated.  We also thank Nicki Taws and Angela Calliess (Greening Australia Capital Region) who undertook the formal vegetation monitoring.

 

After earthworks, planting niches are filled with compost

After earthworks, planting niches are filled with compost

Main slope at Bourkes Gorge #2 spoil dump

Main slope at Bourkes Gorge #2 spoil dump

Liz MacPhee pictured at Bourkes spoil dump one year after planting

Liz MacPhee pictured at Bourkes spoil dump one year after planting

Table 1. Vegetation data recorded on a 50m transect approximately 2 years after treatment.  (Data from Greening Australia Vegetation Monitoring Former Snowy-Hydro Sites Kosciuszko National Park).

Scientific name

Common name

Tube stock

Direct seeding

Transplants from within site

Trees  

 

 

 

Eucalyptus dalrympleana Mountain Gum

X

   
Eucalyptus delegatensis Alpine Ash

X

X

 
Eucalyptus globulus v bicostata Southern Blue Gum

X

   
Eucalyptus viminalis Manna Gum

X

   
Lomatia fraseri Tree Lomatia

X

   
Shrubs  

 

 

 

Acacia dealbata Silver Wattle

x

   
Acacia melanoxylon Blackwood wattle

X

   
Bedfordia arborescens Blanket leaf

X

   
Bossiaea foliosa Leafy Bossiaea

X

   
Bertya findlayii Alpine Bertya

X

   
Cassinia longifolia Shiny Cassinia

X

   
Coprosma hirtella Rough Coprosma

X

   
Coprosma quadrifida Prickly Currant Bush

X

   
Daviesia mimosoides subsp. laxiflora Mountain bitter pea  

X

 
Helichrysum stirlingii Ovens Everlasting

X

   
Kunzea ericoides Burgan

X

   
Leptospermum grandiflorum Mountain Tea Tree

X

   
Leptospermum obovatum River Tea Tree

X

   
Polyscias sumbucifolia Elderberry Panax

X

   
Pomaderris aspera Hazel Pomaderris

X

   
Prostanthera lasianthos Mint bush

X

   
Forbs  

 

 

 

Derwentia derwentiana Derwents Speedwell

X

   
Dianella tasmanica Mauve Flax lily      
Senecio linearifolius Tall Senecio

X

   
Stellaria pungens Prickly starwort

X

   
Ferns        
Polystichas proliferatum Mother Shield-fern

X (divisions)

   
Blechnum spp. fern    

X

Grasses  

 

 

 

Poa ensiformis  

X

X

 
Poa  helmsii Broad leafed snow grass

X

X

 
Poa sieberiana Tussock grass

X

X

Yarrangobilly Native Seed and Straw Farm

Elizabeth MacPhee and Gabriel Wilks

Yarrangobilly Caves is a tourist destination within Kosciusko National Park (KNP), New South Wales. The Yarrangobilly Caves Wastewater Treatment Plant (WTP) has been established to treat greywater produced at the tourist centre, to stop nitrogen moving into the limestone karst system of the caves.

To optimise benefits from the WTP, the Rehabilitation team undertook the planting of locally native grass species in the discharge area, with a view to producing seed and weed-free mulch for use in the KNP Former Snowy Sites restoration program.

Effluent is initially treated using a bacterial blivet and then undergoes an ultra-violet treatment process so that it is within a “greywater” classification. It is then stored in a 200,000 litre tank and released under pressure to a discharge area. Prior to being discharged the effluent is diluted with fresh water to an average ratio of 7:3 (effluent:fresh water) in order to reduce the total nitrogen in the irrigated water to around 10 mg/L, which has been used as a threshold figure for nutrient loading. Once at the right concentration, the effluent is discharged in a large flat sedimentary rock area of about 1 ha in size.  The irrigation area in which the plant species are grown is approximately 0.5 ha.

Vegetation treatments. From 2006 to 2010, some 20,000 plants of a number of species of the grass genus Poa were planted in the discharge area of the WTP, at 50cm spacings (Fig 1).  The four main species were: Poa costiniana; P. fawcettiae, P. sieberiana and P. ensiformis; all native to KNP. Over the last 6 years, more than 300 kilos of highly viable Poa spp. seed has been collected and used in restoration works across the Park. The thatch (seed heads and cut off straw) has also been harvested and used as mulch on some of the sites.

Other species needed for rehabilitation in KNP have also been planted in the site over the last two years. Bossiaea foliosa and Lomandra longifolia have been grown for seed production and a variety of difficult to germinate shrubs have been grown to provide cutting material for propagation.

Soil sampling and soil treatments. Sampling was conducted prior to and after plant harvest to gauge the soil’s physical and nutrient status.  The samples (10cm cores of topsoil and subsoil) were sent to the Environmental and Analytical Laboratories at Charles Sturt University for analysis of Total Phosphorus and Total Nitrogen. (ammonia and nitrates as Nitrogen and phosphorus as Phosphorus (Bray)).

As early soil tests showed that pH reduced, Lime was applied to the discharge area in 2010 at 1 – 1.5 tonnes to to raise topsoil pH approximately 1 unit.

Results.

Seed and mulch production: Within the first 18 month period, nearly 100 kilos of seed was collected. To date over 300 kilos of highly viable Poa spp. seed has been collected and used in rehabilitation across the park, with the 2011/2012 harvest producing approximately 58 kilograms of seed. In the 2012-12 harvest, an estimated 288 kilograms of thatch was removed for use as mulch in restoration areas in the Park.

Soil fertility. More nitrogen and phosphorus was discharged during the 2011/2012 season than could be removed by plants season, with the native species having naturally low nutrient removal rates. Annual soil monitoring and peizometer monitoring of the ground water is keeping track of the use and movement of nitrogen in this landscape and to monitor any changes in soil chemistry.

 Suggestions for improvements:

  • Review irrigation scheduling to ensure the bulk of irrigation is occurring from November to March when nutrient uptake will be at its highest (rather than in the cooler months).
  • De-thatch the grass species at the start of spring to encourage fresh re-growth and therefore improve nutrient uptake over the spring and summer months
  • Test effluent on a regular basis to assess salt load;
  • Further treat effluent to reduce the nitrogen, phosphorous and sodium load;
  • Monitor and adjust pH as required; and
  • Reseed bare patches to maximise nutrient uptake by plants.

 In 2012 a progressive replacement planting program commenced, where sections of the oldest plants were poisoned and replaced with young plants. This continual renewal replanting will ensure the plantation remains actively growing, taking up maximum levels of nutrient and producing high quality seed and mulch.

Acknowledgements.  Funding for this project came from The Former Snowy Sites Rehabilitation project with soil and plant nutrient data provided by D.M McMahon (2008, 2012): Environmental Monitoring Use of Effluent for Irrigation, Yarrangobilly Caves, NSW. Environmental Consultants (agronomy) Wagga, Wagga.

Yarrangobilly grasses ready for harvesting

Yarrangobilly grasses ready for harvesting

The plantings are mainly four local species of Poa

The plantings are mainly four local species of Poa

Sustainable Streets Program, Byron Shire Council, NSW

Graeme Williams

Byron Shire Council’s ‘Sustainable Streets’ program aims to foster community-inspired sustainable behaviour change at a neighbourhood level. The program consists of regular neighbourhood gatherings and sustainability education workshops on topics, including: organic gardening; bush-friendly backyards; rainwater harvesting; solar power and energy efficiency; ethical shopping; green cleaning and, cooking with local produce.  .

Activities. In each participating neighbourhood, residents get together for sustainability workshops and build bonds in the neighbourhood, whilst raising points to fund their own local sustainability project. Currently seven streets in neighbourhoods across Byron and Tweed Shire Councils have participated in the Sustainable Streets program, including: Brunswick Heads; Mullumbimby; South Golden Beach; Mullum Creek; Murwillumbah; Cabarita Beach; Uki.

Analyses of the street’s consumption of energy, water and ecological footprint (i.e. the number of planets needed if everyone lived that lifestyle) were made prior to the program and calculated again after 6 months. (Results are shown in Table 1.)

Table 1. Decreases in energy, water and eco footprint of residents in participating Sustainable Streets in the Tweed-Byron area.

Location of Street Energy Water Eco Footprint
South Golden Beach 5.0% decrease 43.0% decrease 5.5% decrease
Uki 13.0% decrease 23.0% decrease 14.5% decrease
Mullumbimby Creek 13.5% decrease 62.0% decrease 21.0% decrease
Cabarita 26.0% decrease 23.0% decrease 20.5% decrease
Brunswick Heads 12.3% decrease 41.5% decrease 15.3% decrease

Results to date.

Energy. Participants have changed to Greenpower, with 8 families having installed their own solar power system. Other changes have been changing consumption patterns including turning off standbys, installing low wattage lights, wearing jumpers instead of turning on heaters, manual operation of electric hot water boosters, adjusting pool pumps minimum use or converting to a natural pool and insulative cooking.

Water. Five families have installed water tanks, others use shower timers, less frequent bigger clothes and dish washing loads.

Food and garden. Participants have converted to efficient composting or worm farms or installed poultry. Others meet more regularly for neighbourhood food and plant swaps and and buy more local food from a nearby organic farmer and at the Farmer’s markets.

Fuel emissions. Changes included reducing air travel, downsizing the family to more fuel efficient models, increased carpooling and pushbike use.

Environment. Nine families cleared their land of invasive weeds

Lessons. A major aspect of the project has been the strengthening of social connections in the neighbourhood, with many participants drawn into the program to ‘get to know their neighbours’. In an increasingly isolated society, the enhancement of social capital has been one of the most significant achievements of the program and platform to develop local sustainability. It is hoped that additional streets will be launched in the future.

Contact Byron Shire Council’s Sustainability Officer on 6626 7305. Also see http://www.byron.nsw.gov.au/sustainable-streets-program to access the ‘Sustainable Streets doco’ which can be borrowed from local libraries.

Sustainable Streets residents (Photo Byron Shire Council)

Brunswick Heads Sustainable Streets participants (Photo Byron Shire Council)