Caulerpa - Questions and Answers

Q1: What is Caulerpa?

A1: It is a marine seaweed, known scientifically as Caulerpa taxifolia.

Q2: What does it look like?

A2: It is a bright green seaweed with 'palm-like' fronds that can be 5-65 cm in length.

Q3: Where has it been found?

A3: In several NSW estuaries including Lake Conjola, Burril Lake, Narrawallee Inlet, Port Hacking, Botany Bay, Pittwater and Lake Macquarie.

Q4: Why is Caulerpa taxifolia a problem?

A4: It overruns native seagrasses, can dramatically alter marine communities and is difficult to eradicate. In the long term, Caulerpa is a serious threat to the State's coastal biodiversity and may ultimately impact on recreational and commercial fisheries.

Q5: Where is this species found naturally?

A5: Queensland and Lord Howe Island.

Q6: How did it get into NSW waters?

A6: Probably by being dumped from home aquariums.

Q7: Aren't our winters too cold for this species, considering that it comes from the tropics?

A7: No. The Caulerpa taxifolia causing problems in NSW is a cold-adapted strain, apparently able to survive temperatures as low as 10 degrees for lengthy periods.

Q8: How did it become adapted to our cold winters?

A8: Genetic studies have linked it to a cold-resistant strain developed by public aquariums in Europe.

Q9: Has Caulerpa taxifolia caused problems outside of NSW?

A9: Yes. It has invaded the Mediterranean Sea, infesting thousands of hectares, and has also been reported in California.

Q10: Is it legal to keep Caulerpa in my home aquarium?

A10: No, it is illegal to keep Caulerpa in your home aquarium without a special permit from DPI.

Q11: I'd rather not keep Caulerpa taxifolia in my marine aquarium, but it seems to be the only plant I can grow- what can I do?

A11: Seek advice from a specialist marine aquarium dealer. Recent advances in aquarium lighting and water management now allow the cultivation of several other commonly available plant varieties.

Q12: I'm cleaning out my aquarium, which includes Caulerpa - what should I do?

A12: Place any unwanted material, including rocks, gravel coral etc. that may have pieces of Caulerpa attached, in the deep freeze for 24 hours. Secure the material in a plastic bag and place the lot in a garbage bin. Discard water from an aquarium must not be disposed of anywhere it could wash into waterways, such as down a street drain or gutter.

Q13: What precautions should I take when boating in Caulerpa infested areas?

A13: Avoid shallow weedy areas; obey any local vessel exclusion zones or fishing closures; inspect all ropes, anchors, fishing gear etc. before and after use; and check your vessel carefully after removal from the water.

Q14: What do I do if I find some Caulerpa whilst checking my vessel or its equipment?

A14: If you suspect its from a new infestation, contact your local Maritime or DPI office for advice; otherwise seal it in a plastic bag and dispose of it in a bin where it cannot re-enter the waterway.

Q15: I'm out snorkelling and find some Caulerpa in a new area; should I immediately remove it from the seabed?

A15: No; it's better not to disturb any Caulerpa that you find. Take a careful note of its position and advise DPI.

Q16: Why can't I just rip the Caulerpa out of the sea bed?

A16: Because to do so would almost inevitably leave part of the plant behind and cause small fragments to be dispersed into the water. These fragments can be swept to other areas where they can easily grow into new plants.

Q17: What is being done to control Caulerpa in this State's waterways?

A17: The Maritime, DPI and local Councils are working together to educate waterway users about how to avoid spreading Caulerpa. Exclusion zones, fishing restrictions and warning signs have been placed in appropriate areas. Specific vessel wash-down facilities have been provided around badly infested estuaries to help prevent the transfer of Caulerpa to new areas.

Q18: Can anything be done to eradicate this pest?

A18: DPI is currently trialing a number of methods to remove localised infestations, and covering the plants with large amounts of salt has shown initial promise. Removal by hand-picking or mechanical means is rarely effective as it is difficult to get all the plant material or avoid releasing fragments.

Q19: Where can I find more information?

A19: On the Authority's website (see page on seagrass and Caulerpa taxifolia or from DPI. You can also ring 136 186.