Suspected North Island didymo to be tested today

A sample of what could be the first discovery of the devastating alga didymo, also known as rock snot, in the North Island will be tested today.

A trout fisherman in the upper reaches of the Rangitaiki River off the Napier-Taihape road spotted it.

Didymo was first detected in a Southland river in 2004 and now appears in more than 21 rivers and tributaries across the South Island.

Although not harmful to humans, its blooms smother riverbeds, affecting food sources for fish.