Update 2 March 2012:
New research has countered theories that didymo can’t grow in North Island rivers.
The Cawthron Institute has successfully grown the alga in a range of river water from both islands at its laboratories in Nelson.
Didymo in the Waitaki River, seen through the viewfinder.
PHOTO: Radio NZ – Insight
Didymo has now been in New Zealand waterways for more than seven years, but is so far found only in the south where over 150 waterways are infected.
But there is no indication at present that it has crossed Cook Strait.
The New Zealand Institute of Economic Research estimates that didymo has cost $128 million in the past five years due to its negative effect on tourism, recreation and the environment.
New estimates predict a monetary impact of $211 – $855 million from now until 2020.
More on the didymo infestation can be heard on Insight on Sunday.
In the meantime, listen to a preview on Morning Report
A guide to cleaning water related equipment to help slow the spread of freshwater pests.