Locals got an update on a first-of-its-kind research project into microplastics in Lake Wānaka at an event at Wānaka Library this week (Wednesday July 24).

Microplastics are not only in our lake water, they are likely inside some of the trout in the lake, and they have also been found in our drinking water, audiences were told.

Historically very little has been known about microplastics (fragments of plastic less than 5mm in size) in New Zealand’s freshwater lakes and rivers, but the work of marine scientist and PhD student Veronica Rotman is changing that.

With support from WAI Wānaka and volunteers, as well as the University of Auckland and the University of Otago, Veronica has been tracking the incidence of microplastics at various sites around Lake Wānaka.

“At the moment we’ve only got the results from last winter and spring because she’s still busy under the microscope counting thousands of fibres,” WAI Wānaka community connector Jose Cranfield said. 

Jose presented the project update on Veronica’s behalf, sharing that around 75 percent of what Veronica has found so far are microfibres - “things that come off our clothing” - from fleeces, activewear and synthetic clothing. 

Fragments of plastic make up the remaining 25 percent of microplastics found. 

Jose said on average the sampling has found between one and five microplastics per litre of water in the lake.

Certain sites are turning up higher volumes, including Bullock Creek, Roys Bay and Glendhu Bay, among others. 

At this stage there are still plenty of unknowns, including why certain areas are turning up more microplastics and the exact source of the microplastics (including whether they are atmospheric or coming from other sources).

“It’s going to be really interesting watching the next piece of Veronica’s research which is going up into some of the remote areas of the mountains and sampling the snow,” Jose said.

“That will give us an indication of what the atmospheric fallout might be and what percentage of these fibres might be part of the water cycle.”

Jose said Veronica had also completed a very small study of 15 trout from around the catchment “and found on average there were three suspected microplastics in the gut of the trout”.

Another small study by a WAI Wānaka summer student found one to two microplastics per litre in the drinking water supply in Wānaka, and about half that in Hāwea. 

More people in the community will be able to contribute to microplastics sampling and monitoring in the future, Jose said.

WAI Wānaka has launched a new citizen science initiative with two citizen science guides for sampling microplastics, one for communities and one for schools, which are “very much based on what Veronica has been doing in the catchment”. 

Jose thanked Veronica, who trialled and prepared the information within the two guides, selecting the ‘simple sieve’ collection method for its practicality and effectiveness.

WAI Wānaka is promoting the citizen science sampling.

“We’ve got the equipment in the lab at WAI so we can process the samples,” Jose said. “Just next week we have eight volunteers coming in to count microplastics under the microscope from our very first citizen science sampling.”

Learn more about Veronica’s ongoing microplastics research, the citizen science guides, and ways to get involved with WAI Wānaka’s citizen science, here.

Read more: Microplastics under the microscope

PHOTO: WAI Wānaka