Live cells need to be present before a waterway can be confirmed as infected with didymo.
The dead cells were in samples taken from two sites on the Tongariro River - Puketatara and downstream of the Rangipo Dam, and one site each on the Whakapapa, Mangatepopo and Whanganui Rivers. The samples were taken as part of Genesis Energy's monthly water quality sampling programme.
As you would expect, we are treating this with urgency, and are working with our Central North Island partners to determine if there is any live didymo in the area, said David Hayes, MAF Biosecurity New Zealand biosecurity response manager.
A Central North Island didymo action group has been in place in the region for the last 18 months and has a response plan that will be implemented should live didymo be found in the area.
Didymo has not been confirmed in the North Island yet, but every sample like this merely reinforces that the best defence is for all freshwater users to Check, Clean and Dry between waterways regardless of where they are in New Zealand.