Port Botany-Penrhyn Estuary

Client: Port Authority NSW

Location: Port Botany

From June 2008 to June 2011, ecological restoration work was conducted by Port Authority of NSW in association with the expansion of the port at Port Botany, Sydney, NSW. The purpose was to expand and rehabilitate Penrhyn Estuary.

Dragonfly Environmental were responsible for carrying out the world’s largest ever Saltmarsh re-creation. The Saltmarsh works at Penrhyn Estuary involved 2.4 hectares being densely planted with Saltmarsh species. In addition to this 3000m2 of Saltmarsh was translocated within Penrhyn Estuary. The key driver for the Saltmarsh design and plant selection was the requirement for the project to provide habitat for migratory wading birds.

To our knowledge this is the largest recorded Saltmarsh construction project recorded to date, planting over 230,000 Saltmarsh plants, in which Dragonfly Environmental planted that incredible amount of plants in just 14 days. That is roughly 16,429 plants a day.

The main Saltmarsh species occurring in Penrhyn Estuary are Suaeda australis, Sarcocrnia quinqueflora, Sporobulus virginicus and Juncus kraussii. The Saltmarsh species mix planted in the Estuary will increase the diversity of the community by introducing species considered suitable and that currently occur in other Saltmarsh sites in Botany Bay. 

Australia’s saltmarshes are ecologically important ecosystems that link the land and sea, providing productive habitats for a range of species, including migratory shorebirds. Unfortunately, Saltmarsh is an endangered ecological community under the NSW Threatened Species Conservation Act 1995. 

With such a successful project, habitat management and maintenance of the Penrhyn Estuary is key in protecting the shorebird habitat. Dragonfly Environmental is pleased to continue working with Port Authority of NSW at Botany Bay to ensure that shorebird habitat is maintained.

Viewing platforms for the public were created to give visual access to the estuary. Its goal is to minimise the disturbance to the shorebirds and protect the Saltmarsh and seagrass. Dragonfly makes sure that the fencing that keeps out the public and feral animals are maintained and repaired if damaged. Along the public walkways, vegetation is controlled and any weeds or rubbish removed.

Mangroves are seen as detrimental to shorebird habitat as they colonise shorebird feeding and roosting habitat and compete with Saltmarsh for space. Migratory Bird Islands are maintained by reducing the height of any vegetation found growing on these islands, any objects or debris found are also removed.

Saltmarsh plays a key role in stabilising the banks of estuaries, filtering surface runoff, reducing nutrients and providing habitat for fauna. Erosion of Saltmarsh habitat results in loss of planted area, so it is important to monitor any plant loss and the health of the plants. Dragonfly replants any areas that have poor plant establishment or have been disturbed by flood or storm events.

The key objectives of the Penrhyn Estuary habitat enhancement were to expand the existing shorebird habitat, to continue to attract migratory shorebirds and potentially attract more shorebirds.  Also to establish and maintain 2 Hectares of restored Saltmarsh within the site.