A mutated species of tropical seaweed is posing a serious threat to New Zealand's biosecurity, Green MP and Biosecurity Spokesperson Ian Ewen-Street said today.

The threat came to light after the species Caulerpa Taxifolia, became a pest in New South Wales.

"This formerly harmless plant has become highly invasive and now threatens huge ecological damage if it reaches New Zealand waters. It is already a major problem in Australia and it can only be a matter of time before it spreads across the Tasman."

The seaweed was cloned and bred in Germany, France and Monaco for use in aquariums but at some stage it mutated to develop a tolerance for cold water and later was accidentally released into the sea.

It has now infested areas of the Australian coast, where the situation has got so bad that the authorities are banning nets and boats in some of the infected areas.

The mutated species of the seaweed is dangerous because of its tendency to form dense carpets, pushing out native seaweeds and sea grasses and displacing shellfish and crustaceans. Mr Ewen-Street pointed to reports that said the seaweed was already widespread in the Northern Hemisphere, where it was wreaking havoc with various eco-systems. He said the issue highlights how unpredictable organisms can be when they are artificially altered from their natural state and become susceptible to mutations.

"It is vitally important that the Ministry of Fisheries treat the threat seriously, and take all the steps necessary to prevent our biosecurity being breached," he said.

"We simply cannot afford, either economically or ecologically, to let this species become established in New Zealand."

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