Category Archives: South Australia

Basketweaving for ecosystem conservation – Coorong, South Australia

Ellen Trevorrow, Tom Trevorrow and Joan Gibbs

Our concerns for the future supply of our basketweaving rushes (Cyperus spp.) are at the heart of our teaching at Camp Coorong for Race Relations Cultural Education.  The rushes are continually being depleted by stock grazing, mowing, weed sprays and neglect of our waterways and Wetlands of International Significance. The Murray River, Lakes and Coorong were suffering and drying from the 8-year drought and from 200 years of mismanagement of our waterways.  We had turned to using recycled fibres such as string, garden twine and wire. In response to this need for materials from the land, we created an artistic working group, Ngarrindjeri Eco-Art Coop (NEAC),  to embrace the principle of using local materials that would not harm the Earth. Recycling discarded items into art gives new meaning and value to materials that could become an environmental hazard.

Fig. 1. Ellen Trevorrow and NEAC teacher, Jelina Haines, with woven trousers from recycled string.

In the last two years several cultural, spiritual ceremonies were held to bring back the water to the River and the Coorong estuary, to help our totems (plant and animal ngatjis).  In 2009, we were graced by a visit with Grandmother Agnes Pilgrim, who came to Camp Coorong to give a water blessing to bring back the healing waters to the land. Many community members danced and sang to the waters and apologised to the ngatjis for their neglect.  In 2010, the first Ringbalin ceremony was conducted at significant places along the length of the Murray Basin and Rivers, to bring back the health of the river system.  The Talkindjeri Dancers, led by the Ngarrindjeri elder, Major Sumner, travelled for two weeks along the river, stopping at towns along the way to meet with people who joined in the dancing and ceremony on the River. At the end of the river, as Talkindjeri danced on Brown’s Beach at Lake Albert near Meningie, the rains began and the drought was broken.  The rushes returned and the Murray River soon flowed again to the Southern Ocean.

Fig. 2. Tom and Ellen Trevorrow, Ngarrindjeri leaders at Camp Coorong for Race Relations and Cultural Education.

Although the basketweaving plants are growing once again, we are still conscious of the care and use of the weaving rushes. We always balance our need to collect rushes against the supply and reproduction of healthy plants and healthy country. Our ngatjis, the local plants and animals, tell us how we are going, and what we should do to keep the Coorong alive.  Now the Working on Country crews are growing the rushes and planting them out in country, hoping to sustain the future of basketweaving and culture.  Ngarrindjeri people have been relentless about asking the Murray Darling Basin Commission to ensure cultural flows are considered as part of critical human needs.  We also ask that cultural flows reach all parts of the River to sustain our ngatjis, the native plants and the fish stocks. We believe that when our ngatjis die, we die.

Contact: Ellen and Tom Trevorrow, Camp Coorong, Box 126, Meningie, SA 5264, Australia. Tel: +61-8-8575-1557; Fax: +61-8-8575-1448; and Joan Gibbs, University of SA, Mawson Lakes, SA 5095, Australia. Tel: +61-8-8302-5164.

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.

Fig. 1. 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.

Fig 2. Hessian sand bag with Amphibolis recruits after six months

 

WATCH VIDEO Fig. 3. Video of a 3-year-old and adjacent 4-year-old zone where hessian sand bags were deployed showing seagrass colonisation in the older seagrass.

UPDATE FEBRUARY 2016: Re-established Ampibolis at 3 years remains interspersed with patches of bare, highly bioturbated, sand.  The first ~45 seconds of the video in Figure 3 is  a section ~3 years old, where seagrass has not colonised the space between the bags that were deployed, while the remainder is ~4 years old, and the spaces between bags have been colonised.  Natural recruits of Zostera species are prominent in the first 20 seconds. In other areas, Posidonia is recruiting, indicating that biodiversity is building over time as a result of the treatments.

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

UPDATE

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