Controlling the Spread

What has been done?

There have been large-scale efforts to remove the Caulerpa taxifolia since it was first discovered in West Lakes in March 2002. When it was subsequently found in upper reaches of the Port River near Jervois Bridge, the State Government undertook intensive eradication campaigns. These targeted treatments will continue on weed patches.

West Lakes was sealed off and filled with freshwater from the River Torrens. This worked extremely well and, currently, the lake remains clear of the weed.

But because the river could not be sealed off, other measures had to be taken. These included removal of patches of the weed by divers using suction pumps, smothering by salt or black plastic sheeting, with chlorine pumped under the plastic in high-risk areas.

The suction treatment was more than 95% effective while the salt treatment, which involved, 5800 tonnes of salt over areas totalling 60,000 square metres was 97% effective. The black plastic treatment was 100% effective, but could not be delivered to large areas


What is still being done?

PIRSA and SARDI Aquatic Sciences (external site) are continuing to survey and monitor areas of the Port River, North Haven and Barker Inlet to detect infestations and new colonies of Caulerpa taxifolia.

Fringe control, with divers tackling and containing patches with suction pumps, is taking place in Barker Inlet and in areas of the Port River.

PIRSA is also taking action to remove a patch of the invasive weed from an area within the North Haven marina near the public boat ramp.  The operation - where divers will suction up the weed - began on Monday 12 May 2008, and continues for a few weeks. See a video of the work being done at North Haven marina. 

The targeted control of infested areas also covers areas where there is known to be a higher risk, such as near boat moorings, around the Torrens Island power station warm water outlet, and where tides and currents might deposit it.

PIRSA is also creating risk mitigation plans for construction and dredging sites, such as near the Port redevelopment and the third River crossing. Finally, a major public education campaign is underway to inform everyone using the waterway of the problem and how they can help.

An ecological risk assessment for the South Australian strain of the weed is currently being developed by SARDI Aquatic Sciences. When finished, it will provide an indication of how far the weed may spread and what likely impacts can be expected.

Anchoring Ban

Caulerpa taxifolia can survive out of water for many days and grow from very small fragments. This provides it with the ability to be spread over long distances by boating activity, especially anchoring. Consequently, the area where the weed was known to be growing has been closed to anchoring (see Areas closed to anchoring map below).

Anchoring of a vessel is prohibited in the waters of the Port River south of an east west line from Snapper Point to Torrens Island and all waters of the North Arm, Eastern Passage, Angas Inlet, Torrens Reach and Barker Inlet south of an east west line passing through the Inner Middleground Beacon (click here to view map).