Introduced Seaweed (Aquarium Caulerpa)

The pest Caulerpa 


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

The weed is established in the Port River and it is highly unlikely that it can be eradicated completely from South Australian waters. View a short video on the situation at North Haven (.WMV) 4.5MB.

Areas which are infested with the weed are shown on the map of Caulerpa Infestation Areas (.PDF).

The areas where the weed is known to be growing (.PDF) are now closed to anchoring. This includes 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.


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

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