Caulerpa taxifolia (sometimes called ‘Aquarium Caulerpa’) is an introduced species in South Australian waters. It is a bright green alga (seaweed) with main stems that can grow 3 metres long with up to 200 fronds that look like feathers or ferns.

The weed can regenerate and start a new colony from a plant fragment as small as 1 square centimetre.

It is very invasive, grows rapidly and is considered a serious threat to native sea grass meadows and bottom-dwelling communities – threatening fish breeding and feeding grounds. (Fish do not generally eat Caulerpa taxifolia because it contains a toxin that makes it distasteful to them.)

Pieces of the seaweed can survive out of water for up to two weeks. This means that pieces of the weed entangled in boat trailers, anchors and fishing gear can be transported between bays and waterways.

Caulerpa taxifolia in the Port River and Barker Inlet

Caulerpa taxifolia was found first in West Lakes and the area of the Port River near the Jervois Bridge in March 2002. The weed was eradicated from West Lakes however; despite several attempts, it continues to infest the Port River. Further infestations were found in the Port River estuary in early 2004. Following discoveries of the weed’s spread, the State Government began a control strategy and introduced an anchoring ban on all 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 a east-west line passing through Middleground Beacon. The anchoring ban was lifted on 1 March 2011 and replaced with a designated containment area. A map of the containment area is on this website.

Containment Area

The anchoring ban was lifted 1 March 2011. Penalties still apply for people caught intentionally translocating or in possession of the weed in any waters of South Australia as Caulerpa taxifolia is a Noxious Listed Species under the Fisheries Management Act 2007.

The “containment area” is defined approximately as all those waters enclosed by an imaginary line across the entrance of the breakwaters at Outer Harbor, then along the seaward breakwater to its northern end, then northward to the Black Pole, and then in a north easterly direction to the shore. This area is generally accepted as being the Port River estuary. The exact description and coordinates for the containment area can be found on the map on this website.

Click here for a list of frequently asked questions about Caulerpa taxifolia in SA (PDF)

How to avoid spreading the weed

• Avoid boating near or disturbing beds of Caulerpa taxifolia.  

• If you have recently been in the Port River inspect boat trailers, anchors, ropes and chains for pieces of Caulerpa taxifolia before using the equipment in any other area.

• Wash ropes and other equipment in plastic bins using freshwater and bleach after use.

• Inspect fishing equipment, lines, hooks, floats and sinkers before and after use.

• Inspect diving and boating equipment such as wetsuits, bags and other gear before and after use.

• Collect any fragments of Caulerpa taxifolia that you might have accidentally picked up on your equipment, seal the pieces in a biodegradable bag, and deposit in a garbage bin. Do not return any fragments to the sea.

• Do not use Caulerpa taxifolia in an aquarium or release any water, plants or animals from a saltwater aquarium into a drain, creek or the sea.
  
  

If you find Caulerpa taxifolia

• Record the location accurately (use Global Positioning System (GPS) coordinates if possible)

• Record the depth and type of bottom (eg sand, rocky)

• Record how it was found, for example tangled in fishing tackle or anchor, drifting or seen growing

• Collect a sample and store it in a plastic bag

• Don’t throw any suspicious weed back in the water

• Dispose of it in a biodegradable bag and deposit in a garbage bin

Report all sightings of Caulerpa taxifolia to FISHWATCH on 1800 065 522.

More information

You can find more:

• about the different Caulerpas you might find in the brochure Identifying Caulerpas in South Australian Waters (pdf)
• information in the Frequently Asked Questions about Caulerpas in South Australia.