Thought to be caused by the algae Cyclotella bodanica, lake snow has been present in Lake Wanaka since at least 2008 and was discovered in Lake Wakatipu in May this year.
A spokesman for the Otago Regional Council said the algae was found in samples taken during a trophic study of Lake Hawea in September. There have also been reports of the slime being found in Lake Dunstan, but those reports have not been confirmed.
The slime fouled fishing lines and clogged water filters and appliances but was not toxic to humans and animals. The Queenstown Lakes District Council and the regional council would work together to learn more about what caused the algae to appear, why it had affected the three lakes and what treatments were available.
University of Otago limnologist (lake researcher) Dr Marc Schallenberg said it was likely the algae had spread from Lake Wanaka into the other lakes.
Lake snow was similar to didymo, but because it was sticky it could spread more easily by sticking to fishing tackle, wetsuits and boats, Dr Schallenberg said.
To eradicate the algae from the lakes, every last cell would have to be removed, which was impossible, he said. There had been instances of the algae disappearing naturally from lakes overseas, but it was not known why.
Genetic studies showed the algae was very like a North American species but that did not mean it had been introduced. A study of the algae’s DNA would give scientists are clearer idea of its origins, Dr Schallenberg said.
Until it was clear where the algae had come from, it would be hard to put any programme in place to stop it spreading, he said.
Dr Schallenberg had applied for funding to study the lakes’ ecology and the algae to try to understand its emergence and spread.
Ministry of Primary Industries long-term incursion manager John Sanson said the lake snow issue was recently brought to the attention of the ministry.
It was awaiting the results of the Otago Regional Council’s investigation of the issue, he said. Encouraging waterway users to adopt good hygiene practices between waterways was the best way to stop the algae spreading further, he said.
Otago Fish and Game manager Niall Watson wrote to environment Minister Nick Smith and Prime Minister John Key last month highlighting the serious concerns Fish and Game had about lake snow.
