Preventing the further
spread of cabomba
There is no clear picture about how far
cabomba has spread in Australia.
Detection is difficult and there is a low
level of identification skills and awareness
in the community.
The spread of cabomba in Australia has
been aided by the deliberate ‘seeding’
of waterways to ensure a wild supply
for the aquarium trade. This demand
must be stopped and people educated
to buy other species of aquarium plants.
Do not dump cabomba into drains
or waterways
Some strategies to help prevent spread
include the following:
• Dispose of cabomba from aquariums
responsibly, eg by drying and burning
the entire plant. The infestation at
Marlow Lagoon near Darwin is thought
to have started by someone emptying
an aquarium (complete with coloured
rocks) into the lagoon.
• Local agencies need to be able to
close waterways to prevent spread.
• Develop protocols for ensuring
washdown of boats, trailers and
fishing equipment before they leave
an infested site.
Mechanical control requires
ongoing work
Physical cutting and removal is suited to
accessible areas of closed water bodies
with established heavy infestations.
However, cabomba grows so quickly that
treatment by this method is only likely
to maintain a clear water surface for
a few weeks.
Trials of mechanical removal in Lake
Macdonald showed that two treatments
over a month resulted in clearer water
and some regrowth of other desirable
aquatic species.
The cost of mechanically removing
cabomba from dams is very high. At
Marlow Lagoon more than $400,000
was spent initially trying to control the
weed without eradicating it.
Operators and their equipment require
rigorous hygiene protocols to minimise
spread. The removal of plant material
needs to be carefully controlled. Cabomba
easily fragments from disturbance, so
control activities can actually contribute
to spread of the weed if great care is
not taken. Using a venturi dredge, which
is like a giant vacuum cleaner, can help
to overcome this problem. It minimises
fragmentation and also extracts the
root ball.
Hand pulling
Hand pulling by divers is more suited
to isolated plants and small areas.
A 100 m strip was hand pulled in Lake
Macdonald but within two weeks it was
difficult to find a trace of the cleared area.