Introduced seaweed

Aquarium caulerpa (Caulerpa taxifolia) is an introduced aquatic pest in South Australia. It is bright green seaweed with stems that can grow up to 3 metres long. It grows up to 200 fronds that look like feathers or ferns.

It is a serious threat to:

  • native sea-grass meadows
  • bottom-dwelling communities
  • fish breeding grounds.

Fish do not eat the weed because it contains a toxin.

The weed can start a new colony as small as 1 square centimeter. Pieces of the weed can survive up to 2 weeks out of water. This means the weed can spread between bays and waterways on boats or fishing equipment.

Penalties apply for people caught intentionally translocating or possessing the weed in any waters of South Australia. It is a noxious listed species under the Fisheries Management Act 2007. See the noxious species list.

Port River and Barker Inlet

The weed was found in West Lakes and the Port River near the Jervois Bridge in March 2002. It was eradicated from West Lakes. The infestation continues in the Port River despite many attempts to eradicate it.

More infestations were found in the Port River Estuary in 2004. In 2011 a containment area was enforced.

Containment area

The containment is the Port River estuary. See the map for exact description and coordinates for the containment area: Port River estuary containment area.

Avoiding spread

Take these steps to avoid spreading the weed:

  • Avoid boating near or disturbing beds of the weed.
  • Inspect any equipment used in the Port River before using it in any other area.
  • Wash ropes and other equipment after use in plastic bins using freshwater and bleach.
  • Inspect diving and boating equipment for the weed before and after use.
  • Collect any fragments of the weed you may have accidentally collected on your equipment and place it in a biodegradable plastic bag. Place it in a garbage bin. Do not return any fragments to the sea.
  • Do not use the weed in an aquarium.
  • Do not release any water, plants, or animals from a saltwater aquarium into a drain, creek, or the sea.

Reporting the weed

Take these steps to report the weed if you find some:

  • Accurately record the location. Include Global Positioning System coordinates if possible.
  • Record the depth.
  • Record the type of bottom the weed was found in. This may be rocky, or sandy.
  • Record how it was found.
  • Collect sample and store it in a plastic bag. Do not throw any suspicious weeds back into the water.
  • Phone Fishwatch on 1800 065 522 to report your sighting.
  • Dispose of the weed in a biodegradable bag and place it in a garbage bin.

Page Last Reviewed: 19 Feb 2015
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