'No need for concern' over algae in Te Waikoropupū Springs

Wednesday, 27 November 2019

A visitor takes a photo of Dancing Sands Spring, where the algae was first noticed in September.

A green algae found floating on the clear waters of Te Waikoropupū Springs in Golden Bay has been identified as a common, naturally occurring species.

'This is natural and there is no need to be concerned about it,' Tasman District Council environmental information manager Rob Smith said on Wednesday.

A council officer says the algal mats may hang around but could also be dispersed by rain or wind.

The council released the results of testing by Niwa on samples of the filamentous algae, which was identified as Rhizoclonium.

The recent discovery of the algae caused alarm, sparking concern among some people that it may be linked to rising nitrate levels in the springs, which contain some of the clearest water measured anywhere in the world and are a big tourist attraction.

Visitors at Main Spring where algae has been growing in patches of the waterway.

Smith said Rhizoclonium was widespread and tolerated different nutrient concentrations and flow ranges.

**READ MORE:

The algae floating on the water of Te Waikoropupū Springs has been identified as a naturally occurring species.

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* Alarm at algae discovery in Te Waikoropupū Springs

Te Waikoropupū Springs are the largest cold water springs in the southern hemisphere and contain some of the clearest water ever measured on earth.

* Te Waikoropupū Springs report delay surprises Environment Minister

* 'Ongoing silence' over Te Waikoropupū Springs conservation bid alarms**

The appearance of green algae at the Te Waikoropupū Springs in Golden Bay has alarmed locals. The crystal clear springs are one of the region's biggest drawcards (video first published November 2019).

While the council was interested in the size of one of the floating mats, the fact algae was present among the bigger aquatic plants was 'no surprise, especially as we move into longer summer days', he said.

'The nutrient levels in the springs will easily sustain plant growth, which is why there are so many beautiful macrophytes [aquatic plants] present, many of which have algae.'

Rhizoclonium was a 'cosmopolitan genus' with almost 100 species found in nearly all aquatic environments, from freshwater to marine.

'It is certainly a very common species in summer low-flow situations, which is where you may commonly see it,' Smith said. 'There are references to Rhizoclonium being present in hard-water lakes, which would be similar to karst-based springs.'

If it was a long, hot, calm summer, the algal mats 'might hang around and will look a bit mangy but ecologically, they are not an issue'.

'It's really just an aesthetic problem,' Smith said. 'Any management intervention to remove or dislodge the mats and allow them to move on is for the Department of Conservation to manage but I don't see any need to do so. A strong wind and rain event will probably take care of it.'

Niwa and the council were discussing options for future monitoring of the springs generally 'but at this stage, we are still waiting for the Water Conservation Order to provide guidance,' he said.

Golden Bay resident Andrew Yuill and Ngāti Tama Ki Te Waipounamu Trust are joint applicants for a Water Conservation Order to protect the springs, the Arthur Marble Aquifer and associated water bodies.

A hearing before a Special Tribunal closed in August 2018 and its recommendation report is awaited. The length of time the report is taking has caused some frustration for the council and environmental groups. Environment Minister David Parker this month expressed 'my surprise that the process has taken 15 months so far'.

A Tasman District Council staff report, due to be considered by the strategy and policy committee on Thursday, says the Environmental Protection Agency has indicated a decision on the Water Conservation Order is 'imminent'. It also says the Special Tribunal decision is 'likely to go to Environment Court'.