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Marine Pests of Australia

Bryozoan - Watersipora arcuat


This animal is a bryozoan and can survive in tropical and subtropical environments. It is resistant to exposure to polluted water, unlike other bryozoans. They attach to almost any hard surface, forming substantial colonies. Their skeletons are rigid calcium carbonate structures, similar to coral.

It is found attached to rocks and seaweed, along with many artificial structures such as vessel hulls, jetties, pylons and breakwaters. They form substantial colonies on these surfaces, usually around the low water mark.

It can reproduce sexually ot asexually just by a piece breaking off.

Where did they come from?

This species is native to Mexico and the eastern Pacific.

Where are they found in Australia?

It has spread to California, the Hawaiian Islands, New Zealand and Australia. Its presence has been confirmed in South Australia, Queensland and WA and unconfirmed sightings have been reported in Tasmania, New South Wales and Victoria.

How was it introduced?

It is likely to have been transported to Australia attached to the hulls of ships in the late 1800s.

What is its impact?

Watersipora arcuata is a significant fouling species which poses an added threat due to its resistance to toxic paints. This resistance enables it to attach to vessels which have been treated with anti-fouling paints. This means the bryozoan provides a surface for other fouling organisms, which otherwise would not be able to survive, to colonise.

How is it controlled?

There are currently no established control measures.


Watersipora arcuat



What is a marine pest?
How do they get into Australia?
What impact do they have?
What are the main pest species in Australia?
How are we trying to control marine pests?
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