Didymo found in upper Rangitata

For the first time since regular testing for its presence began two years ago, the invasive algae didymo has been found in the upper Rangitata River.

Despite previous infestations in the Rangitata Gorge, the upper sites had tested negative since testing began.

The Department of Conservation (DOC), Fish and Game and the local community are disappointed with the find, especially since the Peel Forest and Rangitata Gorge community have tried hard to prevent didymo from spreading into those areas.

Sally Stephens of the Rangitata Gorge Landcare Group said it was "very disappointing but not the end of the world".

"Despite didymo cells being present in the actual gorge for the last couple of years, we haven't seen it bloom there. The fact that the river floods with the nor'west rain and remains dirty for long periods gives us reason to hope that we will not get the awful blooming found in other infected waterways.

"We still need to be vigilant and we still need to clean gear and jet boats before and after use in the Upper Rangitata."

DOC will hold a survey to identify the extent of didymo spread and to determine management measures, which could include providing more decontamination facilities. Biodiversity programme manager Kennedy Lange said people still needed to take whatever measures they could to prevent further spread.

The upper Rangitata River is one of the most important braided river habitats nationally for specialist species such as the endangered black-fronted tern (tara) and wrybill (ngutu porore) and the endangered upland longjaw galaxiid, a native fish.

"These sites are especially critical at this time of year for breeding birds," Mr Lange said.

- © Fairfax NZ News