Management of Caulerpa in NSW – Frequently Asked Questions

Is it illegal for me to have Caulerpa in my aquarium at home?

Yes, the sale and possession of Caulerpa is prohibited under the Biosecurity Act 2015.

Heavy fines apply for the reckless or intentional spread of Caulerpa.

What do I do if I find Caulerpa on my boat, trailer or equipment?

Waterway users should thoroughly wash down and check equipment for Caulerpa after use. Caulerpa can remain viable out of the water for days in the right conditions. Collect and dispose of any fragments in a plastic bag into general waste. Never return any Caulerpa fragments to the water.

Can I remove Caulerpa if I see it in my waterway?

Waterway users should not disturb any populations of Caulerpa as this can cause fragments to be dispersed to other areas where it can settle and establish new populations.

Will control works be supported in affected estuaries?

No. The only control method thought to be effective for removing Caulerpa is applying extremely large volumes of pool salt. However, this will not guarantee complete eradication and is not considered feasible in many circumstances.

This method also requires a permit, which includes comprehensive environmental assessment. If approved, the work may only occur with direct DPI involvement.

There is no guarantee that Caulerpa will not reoccur in an estuary afterwards due to fragmentation, or in undetected populations of Caulerpa within that same waterbody.

What evidence is there that the impacts of Caulerpa in NSW are not severe?

Caulerpa is not considered as severe as once thought following 15 years of scientific observations and published research into the impacts of Caulerpa on native seagrasses in NSW:

  • In NSW, Caulerpa does not kill native seagrasses; it tends to grow primarily on the edges of seagrass beds and less commonly is found interspersed with seagrass
  • In recent years, the density of Caulerpa populations has been observed to be significantly reduced in most estuaries as a result of natural fluctuations in salinity and temperature
  • Caulerpa can opportunistically occupy barren space where it has been found to create habitat that is similar to native seagrasses in some regards (eg. for some fishes but not seahorses)
  • Caulerpa traps sediment in a manner similar to that of the native Zostera capricorni
  • There is evidence that native seagrasses in NSW are capable of recovering after invasion by Caulerpa
  • Caulerpa can differ from native seagrass habitats in relation to invertebrates living in the sediments. More research is required to investigate to what extent changes in sediment chemistry are driven by the density of vegetation as compared to the type of vegetation (i.e. Caulerpa versus seagrass).

Will monitoring of Caulerpa continue?

Yes. Passive surveillance through community, stakeholder and research projects will continue.

Will active monitoring by NSW DPI continue?

No. Active monitoring of Caulerpa has ceased. DPI will continue to investigate reports of Caulerpa infestations in waterways where it has not previously been found.

How can I help?

You can help us by sharing advisory information with your friends, colleagues or fellow stakeholders to raise awareness about the importance of cleaning boats and equipment before moving to other waterways. Reports of suspected new detections in new locations can be made to DPI Aquatic Biosecurity.

What do I do if I find a new population of Caulerpa in a place where it is not known to occur?

Please report new detections of suspected Caulerpa to DPI Aquatic Biosecurity.

What will DPI do if a new incursion of Caulerpa is detected?

DPI will investigate new reports of Caulerpa in waterways where it has not previously been known to occur, to confirm and quantify the incursion, and to inform potential communication activities. Control efforts are unlikely to be supported due to the challenges of successfully eradicating Caulerpa.

What do I do if I know someone is keeping or is recklessly spreading Caulerpa?

Please report all such activity to DPI Aquatic Biosecurity.