Category Archives: Coastal & marine

Seagrass meadow restoration trial using transplants – Cockburn Sound, Western Australia

Jennifer Verduin and Elizabeth Sinclair

Keywords: marine restoration, seagrass, Posidonia australis, transplant, genetic diversity, microsatellite DNA, provenance

Cockburn Sound is a natural embayment approximately 16 km long and 7 km wide, to the west of the southern end of the Perth metropolitan area. Its seagrass meadows have been reduced in area by 77% since 1967, largely due to the effects of eutrophication, industrial development and sand mining. To answer a range of questions relevant to seagrass restoration, we (i) carried out a transplant trial, (ii) monitored the impact and recovery of the donor site, and (iii) retrospectively assessed genetic diversity in the transplant site.

Methods. (i) The transplant trial was conducted between 2004 and 2008 in an area totalling 3.2 hectares of bare sand at 2.2–4.0 m depth on Southern Flats, Cockburn Sound. Donor material was sourced from a naturally occurring seagrass meadow on Parmelia Bank, north of Cockburn Sound, approximately 16 km away from the transplant site. Sprigs (15–20 cm length) of a dominant local seagrass, Posidonia australis Hook.f., were harvested from donor material and each sprig tied to a purpose-designed degradable wire staples (30 cm in length) and planted and secured into a bare sandy area at 50 cm shoot spacing by SCUBA divers (Figure 1). Sprig survival was periodically monitored in 10 m x 10 m representative sub-plots (15–20 plots per hectare).

(ii) For the meadow recovery study, several plug (a clump of seagrass excavated) extraction configurations were examined in P. australis meadows to monitor shoot growth into plug scars, with metal rings placed into the resulting bare area to monitor shoot growth into it at 3, 10, 13 and 24 months. Rings of 8.3 cm diameter were placed into adjacent undisturbed meadows to act as reference plots. (iii) Shoot material was collected from established plants for microsatellite DNA genotyping from the donor site in 2004, and from the 2007/2008 plantings in the restoration site in January 2012. Genetic sampling from the restoration site was done from mature shoots only, to ensure we were sampling original donor material. DNA was extracted from shoot meristem and genotyped using seven polymorphic microsatellite DNA markers (Sinclair et al. 2009).

Fig1

Figure 1. Transplants in situ, prior to the pegs being covering with sediment (Photo Jennifer Verduin)

Results. (i) The transplants have grown well to fill in gaps and become a healthy, self-sustaining meadow, with first flowering in July 2010, three years after initial transplant in 2007. There has also been considerable natural recruitment in the area through regrowth from matte and new seedlings (Figure 2). (ii) No significant differences in shoot growth between extraction configurations were observed in the donor meadow, and there was an increase in shoot numbers over two years. Based on the number of growing shoots, the predicted recovery time of a meadow is estimated at three years. (iii) Genetic diversity was very high in the restored meadow (clonal diversity R = 0.96), nearly identical to the donor meadow.

Fig2

Figure 2. Aerial view of the restoration site (within yellow markers), with natural recruitment occurring from vegetative regrowth and new seedling recruits (Photo Jennifer Verduin, 2010).

Important considerations for long-term success and monitoring. While several important questions have arisen from this trial, it demonstrated that (i) the transplants achieved a high level of establishment within a few years; (ii) the high genetic diversity in the donor site was captured and retained in the restored meadow; and (iii) surrounding sandy substrate is being colonised by P. australis through regrowth from the matte and natural recruitment from seeds dispersed within and/or from other meadows, (the latter potentially helping to ensure the long-term viability of restored seagrass meadows.)

Partners and Investors: This project was carried out as part of the Seagrass Research and Rehabilitation Program through Oceanica Consulting Pty Ltd, with Industry Partners Cockburn Cement, Department of Commerce (formerly Department of Industry and Resources), WA, Department of Environment and Conservation WA, The University of Western Australia, and the Botanic Gardens and Parks Authority, WA.

Contact: Jennifer Verduin, School of Environmental Science, Murdoch University, Murdoch, WA 6150 Australia Email: J.Verduin@murdoch.edu.au; Elizabeth Sinclair, School of Plant Biology, University of Western Australia, Crawley, WA 6907 Australia Email: elizabeth.sinclair@uwa.edu.au. If you are interested in becoming involved with seagrass rehabilitation through student projects please contact us.

 

 

Fingal Headland Maritime Themeda Grassland Restoration

Keywords: Grassland, Themeda Grasslands on Sea-cliffs and Headlands, headland ecosystems, bush regeneration, Fingal Head Coastcare, Plectranthus cremnus

Kieran Kinney

Fingal Head, whose first inhabitants are members of the Cudginburra Clan, is a famous beauty spot in the far north coast of NSW, heavily utilised for recreation such as fishing, surfing, whale and dolphin watching and family outings. It is estimated that upwards of 50,000 visitors per annum use the site. As a result of this and other impacts including unfettered goat grazing (commencing around the lighthouse in the late 19th century), the site has many management challenges, including extensive gully and rill erosion, trampling of native vegetation, wildflower harvesting and weed invasion.

Prior to treatment, the ground cover layer was almost completely dominated by a form of the exotic Buffalo Grass (Stenotaphrum secundatum) and a suite of other weeds including Bitou Bush (Chrysanthemoides monilifera ssp rotundata). Because similar headlands in the region (Norries Head and Hastings Point Headland) support the State-listed  Endangered Ecological Community Themeda Grasslands on Sea-cliffs and Headlands it is assumed that Kangaroo Grass (Themeda triandra) was native to the site and became locally extinct due to the history of grazing and weed invasion.

Project works: In 2009 Fingal Head Coastcare determined that work to address the serious weed problems should commence and that trials be undertaken to reintroduce Kangaroo Grass.  Several small plots (100m² ea.) were sprayed with herbicide and slashed (Fig 1). Regenerating weed was regularly removed.

Fig 1: Trial plot 1 -  Natural regeneration within patch of treated Buffalo Grass

The plots were sown with Kangaroo Grass seed collected from other headlands in the region. The material used is a genetically distinct coastal form of Kangaroo Grass that exhibits a unique decumbent growth habit. Ripe fruiting culms were distributed in quadrats as well as randomly over the plots.

In addition to the Kangaroo Grass trials, efforts were made to plant a variety of typical Grass and Forbland species, including Golden Everlasting Daisy (Xerochrysum bracteatum), Evolvulus alsinoides and Chamaechrista maritima. These were propagated in the Fingal Coastcare nursery from seed and stock sourced at nearby headlands.

Results. Regeneration of native species  was extensive across the plots (Figures 2a and 2b). Regenerating native species included Prickly Couch (Zoyzia macrantha), Native Violet (Viola banksii), Angled Lobelia (Lobelia alata) Plectranthus (Plectranthus cremnus) and Beach Bean (Canavalea rosea).

Fig 2a: Typical Buffalo Grass infestation prior to commencement of trials.

Fig 2b: Example of regeneration of native grasses Prickly Couch and Blady Grass after works (Plot 1, 2011).

Both the Kangaroo Grass  and the Everlasting Daisy (Figure 3) have since naturalised on the site. However, the plots revealed very poor rates of germination of Kangaroo Grass, approximately 1 in1000. Germination rates were much higher under controlled nursery conditions

Fig 3: Everlasting Daisy re-established and recruiting on Fingal Headland.

Outcomes and lessons learned The low rate of Kangaroo Grass germination is not regarded as a major impediment to the overall success of the project. As natural processes and cycles come into play, it is probable that Kangaroo Grass will become a significant part of the biota on the headland. That is,  achieving the ultimate aim of a Closed Tussock Themeda Grassland is probably unlikely through reintroduction from the seed sowing methods we used, but may occur naturally over time.

The extensive natural regeneration of the threatened Plectranthus cremnus is a major success of the trials.  This herb species is habitat for a local population of Blue-tongue Lizards and Bearded Dragons. It is a major food source for the reptiles, supplementing their animal diet, which may be very seasonal.

Erosion control has been significantly reduced through active intervention, using hard infrastructure in combination with ‘low key’, passive techniques such as strategic plantings and bush debris.

Local school children are involved in the plantings on an ongoing basis, and have picked up vital local knowledge and site ownership along the way. This project has been a major education experience for the Coastcare group, the Tweed Byron local Aboriginal Land Council and many members of the Fingal Head Community who were previously not aware of this Endangered Ecological Community . The trial areas are now a profusion of wildflowers almost the year round and the Coastcare volunteers receive many compliments from the passing public. During working bees on the site considerable energy is devoted to educating the public about the Grasslands in the hope that this will assist in their protection (and also because it is a lot of fun!)  Anyone who visits the site will be captivated by the delicate beauty of the native flora, the awesome scale of the natural scenery and will surely agree that something special is happening here.

Where to from here?: One of the most challenging and pressing issues facing the headland is uncontrolled pedestrian traffic. Although this may be unavoidable to some extent, it is desirable for the long term health of the ecosystem that some control methods be introduced to the site. Trials have been conducted using bush debris with limited success. More permanent methods would have to be carefully designed and implemented in order to blend with the unique aesthetics of the site. Boardwalk construction has been very successful in key areas, however this type of construction is deemed inappropriate for the grassland proper.  Dense vegetative barriers consisting of tussock forming species such as Spiny Mat Rush (Lomandra longifolia) and Knobbly Club Rush (Isolepis nodosa) are being planted to rationalise the trackways and guide pedestrians away from more sensitive areas.

In terms of the vegetation restoration works, ongoing and extensive follow-up weed control is required and it is envisaged that as each plot is stabilised and achieves manageable levels of autonomy, new areas will be opened up for weed control. It is recommended that a formal Restoration Plan be developed and implemented, perhaps through funding avenues or the involvement of Environmental Science students. This would greatly assist guiding the works over an extended period and help achieve the best possible outcomes for Fingal Headland and the wider community.

Partners and Investors: Fingal Head Coastcare Inc. consulted with the Tweed Shire Council, The Tweed Byron Local Aboriginal Land Council and a number of community groups to plan this project. The community groups include the Fingal Heads Community Association, the Fingal Head Public School, Fingal Rovers SLSC, local businesses and other Tweed Coast Dune care groups.

Contact : Kieran Kinney,  Fingal Head Coastcare Project Manager, 28 Kurrajong Ave Cabarita Beach 2488. Tel:  +61 266763002 Mob: 0457356175.   Email : kierankinney@gmail.com

Kirra Dune Revegetation – Queensland.

Key words.  Dune reconstruction, strand ecosystem,

Mark Bibby

A project was developed in 2009 to remove sand from the intertidal area at Kirra to form a new series of dunes along a 1.5km stretch of beach from Kirra to Bilinga, on the far south coast of Queensland (Fig 1).  While the purpose was to maintain the beach amenity and reinforce a buffer to the shoreline, the reconstruction of the dunes (to an average height of 4 metres and the width v from 25 to 60 metres) also involved reinstating native plant communities along the dunes for stabilisation and the conservation of biodiversity.

Fig 1: Project area – 1.5km stretch of beach from Kirra to Bilinga, Queensland.

Revegetation was conducted in the frontal dune area of the project site and in strategically placed infill planting cells between the frontal dune and the existing vegetation landward edge of the project site (Fig 2). Four locally occurring dune species were selected: Spinifex (Spinifex hirsutus) 65%; Beach Bean (Canavalia rosea) 5%; Goats Foot Convolvulus (Ipomoea pes-caprae) 15%; and Vigna (Vigna marina) 15%.

Fig 2: Revegetation of the dune system using infill planting cells and four locally occurring plant species (April 2011).

For a 12 week period the plants were monitored and watered with a 25,000L capacity off-road truck, with plants replaced as required. The site was then maintained for a period of twelve months post-planting to promote good growth of installed plants, prevent weed incursion, ensure dune stability through increased native vegetation cover and assist natural regeneration of dune species.

The total length of the planting area is 1515m and  approximately 18,000 tubestock were planted out over an area of 18000m2 by a team of 6, who planted a total average of 4500 plants per day.

Results. Planting survival rates varied mainly due to mobile sand and anthropogenic disturbance. Good rainfall over the installation period and for 4 weeks following planting ensured establishment was successful (Fig 3).

Fig 3: Revegetation of dune system 5 months after works (Sept 2011)

At 12 months after the planting on the foredune, Beach Spinifex (Spinifex sericeus) densities are approaching, or in some areas have reached, densities expected for a naturally established frontal dune (Fig 4). Since planting, the nursery-spelled Beach Spinifex have flowered and seeded, however the bulk of the increase in biomass is due to extension of the runners. Beach Spinifex runners have travelled in all directions across the dune (i.e. including up inclines). Small swales of windswept sand can be seen captured in front of Beach Spinifex. Of the three species planted on the frontal dune, Beach Spinifex (overall) has shown the greatest increase in area covered.

Fig 4: Revegetation of dune system 12 months after works (April 2012).

The other two species Vigna (Vigna marina) and Beach Morning Glory (Ipomoea pes-caprae) have also done well, although not increased their biomass as rapidly as the Spinifex. The plants, however, have had a good survival rate and throughout December to April 2012 have seen an increase in their rate of growth. Based on the slower (compared to the Spinifex) growth rates that both the Vigna and the Beach Morning Glory exhibited throughout the establishment period either:

(a) they naturally require more time to establish;

(b) their growth rate throughout winter months is less than Spinifex;

(c) they are more sensitive to wind-blown sand than the Spinifex; or

(d) a combination of factors.

Growth rate, however, was not a specific metric that influenced the decision to include these species in the revegetation species selection; the primary reason for their inclusion was to increase in situ species richness in the mid- to long term. Based on this, their inclusion has been successful. As mentioned previously they are now growing more rapidly and both species have flowered and produced seed.

Runners are beginning to connect the infill planting cells with the frontal dune row plantings. In addition to the three species used in the frontal dune plantings, Beach Bean (Canavalia rosea) was also included. The establishment, growth and survivorship of Beach Bean has been similar to that of Vigna — a period where growth appeared minimal and then more rapid growth throughout summer 2011/2012.

Overall survival rate is approximately 80%, however survival rate of individual plants is probably not the best measure of success for a project of this nature. Percentage cover or biomass is a more appropriate measure. Despite this, whichever measure of success is chosen the project has met and exceeded requirements.

Plant abundance and vegetative cover are very good to excellent. Combined with the species composition (richness) many areas of the frontal dune are indistinguishable from a naturally occurring frontal dune. The plants are reproducing and increasing their abundance; at this point predominantly vegetatively (i.e. ‘runners’) however all species have produced seed and these could reasonably be expected to add to the plant population.

The plants are well established and (in the absence of any extreme natural events or destruction by intent) self-sustaining.

Lessons learned.  Beach Spinifex (Spinifex sericeus) is a rapid colonizer of frontal dunes and was the first of the four planted species to reinforce a buffer for the newly created dunes.

The largest threats against successful establishment are:

  • Anthropogenic disturbance through the planting establishment area. This resulted in breaking the ‘crust’ that forms on the top of semi-stable sand, making the underlying sand more susceptible to erosion.
  • Sandblow that covers or undermines plants in the first few months post planting.

Because the sand was “sterile” (due to it having been reclaimed from the intertidal zone and lacking a seed bank), weed invasion, up to this point, has been minimal. This may suggest that weeds predominantly recolonise natural dunes due to accumulated seeds and other propagules persistent in the sand.

Stakeholders: The Department of Environment and Resource Management (DERM) has been responsible for the project management of the Kirra Beach Restoration Project. The Gold Coast City Council (GCCC) is a key stakeholder and the primary service provider for the works.

Contact: Mark Bibby, Gecko Regen, / 139 Duringan Street,Currumbin, Qld, Australia. Tel:  +61 (7) 5534 6395. Email: admin@geckoregen.org.au ; http://www.geckoregen.org.au/

Recent works supplementing the ongoing regeneration of coastal vegetation at Dirawong Reserve, Evans Head, NSW

Key words: bush regeneration, Bitou Bush, Leptospermum laevigatum, abseiling for weed control, Indigenous land management

Bob Jarman

Dirawong Reserve is a 300 ha crown reserve for the conservation of Aboriginal cultural heritage, flora and fauna and recreation, Located on the southern peninsula of the river mouth adjoining the village of Evans Head in Northern NSW, the reserve includes beach areas, frontal dunes, cliff faces, coastal heath and ti tree swamp. The reserve is managed by the Dirawong Reserve Trust, which is committed to implementing its Plan of Management by upholding the values of Indigenous heritage and improving restoration of the natural environment through strategic and continuous projects.

The coastal zone, largely involving coastal strand plant, dune, heath and grassland communities, has been subject to a range of impacts including sand mining, off-road driving and weed invasion over half a century, leading to high levels of weed dominance. Bush regeneration works have been ongoing since the early-mid 1980s and include a combination of volunteer programs and engagement of contractors. A range of innovative techniques have been used to treat Bitou Bush (Chrysanthemoides monilifera ssp. rotundata), Glory Lily (Gloriosa superb) and Coastal Tea Tree (Leptospermum laevigatum).  Results of the combined efforts over time has achieved the decline of weed over large areas of the site, with extensive regeneration of native vegetation.

History of Indigenous community involvement. As a result of inspiration gained from the highly successful employment of Indigenous Rangers during the 1970s at the nearby Bundjalung Flora and Fauna Reserve (now Bundjalung National Park), local Bundjalung community members were employed on a casual basis at Dirawong Reserve during the 1980s and 1990s. Experienced supervision and training was provided for the bush regeneration works, which focused on control of Bitou Bush, using manual techniques. As part of the program, elders from the Bandjalang community worked alongside younger workers, passing on both Traditional Ecological Knowledge and culture relating to this important site.

The Trust, which is made up of representatives including from the local Bandjalang clan Traditional Owner group, has a policy of seeking Traditional Owner personnel for any contracts that come up in the future. Such employment would mean that four generations of Indigenous natural resource management workers will have been directly involved in managing Dirawong Reserve over the last three decades.

Recent works. To complement ongoing regeneration projects, recent (three-year) funding through the NSW Government Environmental Trust Program has allowed Dirawong Reserve Trust to engage contractors to manage the continuation of the project, applying a range of both standard and Dirawong Reserve’s own innovative techniques to treat Bitou Bush, Glory Lily and Coastal Tea Tree among other weeds.

Before Bitou Bush treatment

One successful innovation, developed in the 1990s by the site’s long time regeneration advisor, Ellen White, has been the cutting of Coastal Tea Tree below the lowest branch or cutting off all branches, which has proven to be sufficient to kill the plant.. This method eliminates the need to use herbicides and reduces strain for operators.  This has been applied at other areas of the headland more recently, using chainsaws.  To assist with the ongoing and long term work of treating Bitou Bush, the Trust has engaged a specialist abseiling bush regen team to spot spray or cut and paint Bitou Bush in difficult locations such as cliff faces. (See photos above).

After Bitou Bush treatment by abseiling regenerators at the top of a coastal gorge at Dirawong Reserve NSW north coast

Results to date. Progress has been steady and highly effective over recent decades, although there is much work remaining, in terms of Glory Lily follow up and there are still substantial areas of Bitou Bush to treat.   To date, Coastal Tea Tree works have been carried out over 12 ha, with no sign of resprouting from cut stumps in any age class. (See photos of some of the recent works above). Treatment of cliff faces by abseiling contractors has resulted in effective treatment of Bitou Bush with no significant off-target damage (see photos below).  No soil destabilisation has been generated from the works.

Before (c) and after (d) cutting of Coastal Ti-tree. All photos: B Jarman.

Acknowledgements: Funding has been received from a range of sources, most recently the NSW Government’s Environmental Trust Program.  We also acknowledge the dedicated work of our bush regeneration volunteers and committee members over the decades since the mid 1980s.

Contact: Dirrawong Trust, P.O. Box 90, Evans Head, NSW 2473, Australia. Email: dirawong.trust@gmail.com.

Seagrass restoration off the Adelaide Coast via facilitating natural recruitment

Key words: Amphibolis, nanotechnology, seagrass loss, eutrophication

Jamie Quinton

Over the past 50+ years, more than 5,000 ha of seagrass has been lost along the Adelaide metropolitan coast, largely due to excessive nutrient inputs. Following substantial investment in reducing nutrient inputs, limited natural recolonisation has been observed. This is possibly due to sediments now mostly being too mobile for seagrasses to colonise.

The trial. An experiment was carried out to stabilize areas adjacent to existing seagrass meadows, deploying hessian sand bags to provide a stable substrate for the recruitment of Amphibolis seedlings. These seedlings are produced viviparously by the parent plant and have a ‘grappling hook’ for attachment to the substrate.

Hessian sand bag covered by an outer layer of coarse-weave hessian

Various types of sand bag were trialed, with the most effective being a standard hessian bag covered with an outer layer of coarse-weave hessian. These bags can simply be dropped over the side of a boat, and do not require divers to deploy them, thus substantially reducing the coast of restoration. Densities of recruits averaged 150-350 seedlings per m² for different treatments, with individual sand bags attracting densities up to ~900 seedlings per m². Long-term survival (i.e. 3 years or more) occurred for up to 72 individuals per m², although many treatments failed over this duration. Preliminary estimates suggest that restoration costs could be less than $10,000 per ha, provided that long-term success and eventual meadow formation can be achieved. Initial studies of the bags suggested that spatial configuration was not important.

Hessian sand bag with Amphibolis recruits after six months

Lessons learned and future directions: The key issue so far has been the inconsistent quality of the hessian used for the bags – some batches deteriorate rapidly leading to loss of all seedlings, whereas others last longer. The focus is now on trialling nanotechnology to improve the hessian longevity, while still retaining its long-term biodegradability. There is some suggestion that half-buried bags also perform better, possibly due to water flow through the sand in the bags, and this needs further study.

Stakeholders and funding bodies: SA Department of Environment & Natural Resources, SA Water, Adelaide & Mount Lofty Ranges Natural Resource Management Board, Australian Research Council, South Australian Research & Development Institute, Flinders University

Contact information: Dr Jason Tanner, Principal Scientist – Marine Environment & Ecology, SARDI Aquatic Sciences, PO Box 120, Henley Beach, SA. 5022. Tel: +61 8 8207 5489 Email: jason.tanner@sa.gov.au

Townsville’s environmental awareness-raising ‘Celebrate the Sea’ Festival

Key words: environmental education, science-practice collaboration, marine debris, Clean Up Australia Day, National Seaweek

Carla Hutchinson-Reade

On Clean Up Australia Day 2011, NQ Dry Tropics hosted a new event called Celebrate the Sea Festival in Townsville to promote National Seaweek. The aim of the event was to place a spotlight on the achievements of local environment groups and marine scientists.

Residents were invited to contribute towards creating a more sustainable future on their local beach of Pallarenda in a practical way. The 146 volunteers removed 52 bags of rubbish that were destined to become deadly marine debris. All volunteers of the clean up were rewarded with a free BBQ lunch, educational activities including a bush tucker walk and marine scientist presentations.

Seven experts spoke about sea turtle conservation, our changing climate, wetlands, creating sustainable behaviour changes and permaculture design. The presenters were from organisations including James Cook University, Reef and Rainforest Research Centre and Marine Wildlife Australia. Seven environment groups had displays and ran educational activities for both young and old. Additional awareness was raised through television and radio interviews on the day and NQ Dry Tropics’ events leading up to the Festival. NQ Dry Tropics’ Laura Dunstan spoke about marine debris in four television and three radio interviews.

Children grabbed their chance to hug and talk to three giant mascots including NQ Dry Tropics’ favourite employees, Duey the dugong and Tiny the Tern. Duey asked people to protect their precious seagrass and to slow down and look out for dugongs when boating. Tiny’s concern is protecting precious nests on beaches. Reef HQ’s Lucky T Turtle sold the ‘say no to plastic bags’ message and the ‘4 R’s of rubbish – refuse, reduce, reuse and recycle’.

The Celebrate the Sea Festival inspired and educated residents about marine science and conservation and encouraged environment groups to collaborate and learn collectively. Its success has meant that NQ Dry Tropics is keen to host Celebrate the Sea Festival in 2012.

Donations towards the event were kindly supplied by Bunnings, Ergon Energy, Doug Edes Party Hire, local food suppliers and the environment groups that exhibited including Conservation Volunteers Australia, Reef HQ Great Barrier Reef Aquarium, Marine Wildlife Australia, Permaculture Townsville, Sea Turtle Foundation, Coastal Dry Tropics Landcare Inc and NQ Fly Fishing.

Contact: Laura Dunstan, Community Support Officer, NQ Dry Tropics, (07) 4724 3544 or email laura.dunstan@nqdrytropics.com.au