A Teeny Tiny Truth

Aquatic Life
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Community Wellbeing
Healthy Ecosystems
Risks to our Catchment
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Water Quality

Microplastics in our waterways

Introducing ‘A Teeny-Tiny Truth’ – a research project that investigates microplastics in our fresh water, while empowering our community to participate and drive change.
Veronica looking closely at a jar of sediment

Read on for more information about the project and what inspired it or click on the buttons below to jump ahead.

Why Microplastics?

A tiny bit of history

In 2022 a group of Mount Aspiring College year 7 students collected, sorted, recorded and disposed of rubbish along a 50-metre stretch of the waterfront. Several groups of students studied a small transect of this area and came up with significant quantities of small plastic fragments.

Students collecting rubbish
Kids on the beach sorting through rubbish

This sparked a question: If we’re finding these plastic fragments on the lakefront, what’s in the water and where are they coming from? Here at WAI Wānaka, we saw this as an opportunity to bring freshwater scientists and community together to investigate further.

We connected with Veronica Rotman, who immediately jumped at the idea of microplastics research here in Wānaka. Therefore we pulled together a project and began connecting with partner organisations. As Veronica collects baseline data, we’ll take her methods and adapt them into something WAI Wānaka can continue as an ongoing community science project.

What are microplastics?

Veronica with an earlier sampling net
Noemi (volunteer helper) and Veronica


1) The Mighty Manta

The Manta Trawl is like the superhero version of fishing nets, named and designed after the awesome Manta Ray that glides through the ocean. It’s got these cool extensions on the front around the opening, and wings just like the Manta Ray’s. These extensions help the trawl capture all sorts of organisms and microplastics that hang out near the water surface. The Manta wings help with flotation.
The Manta Trawl in the water with the lake in the background

Back in the 1980s, some smart folks came up with this design to collect organisms and stuff floating on the ocean surface. Sure, there are other trawls out there, but the Manta trawl is the chosen one. It is all about stability, buoyancy, and precision when it comes to sampling the water layer. So, it is the go-to method for scooping up microplastics in salty and fresh waters.

Our Manta Trawl was made by our supporters at Wai innovation in Wānaka. It has two main parts: the frame and the collecting net.

The Frame

The frame is made of tough stuff like stainless steel or aluminium so that the opening or mouth of the net stays the same during sampling. And here’s the cool part: on each side of the frame, there are these floaty things called “wings” or floaters. They help keep the Manta net floating and steady as it does its important job.

The Collecting Net

The collecting net is 3m long made of really thin mesh, about 333 microns. You can either tow it behind a boat horizontally or let it chill in a river. It then skims the surface grabbing everything in that top layer (15-25cm). It is perfect for collecting microplastics, which is crucial for our project.

Manta Trawl in the water
Manta Traw collection net

The speed at which we haul the Manta trawl is a big deal because turbulent waters can mess up how well microplastics float, and we need water to be pretty calm for it to work right. The stuff on the surface is influenced by wind, waves, currents and temperature.

To figure out how much water we are sampling each time, we are using a flow meter. We plop it in the middle of the opening on the net and let it do its thing. That way, we can calculate the volume of water and the current.

Flow meter in the net
Flow meter in its place in the net of the Manta trawl
Flow meter device
Flow meter

2) The Dutch Sampler

Microplastics are everywhere. They are contaminating pretty much all parts of the environment, which is why we are not only taking water samples but also grabbing some sediment for our research.

Now, the thing about microplastics in sediment is that they are not spread out evenly. It is all about their properties and the environment, like how the wind and currents play into it. So, the results we get will really depend on where we are sampling, like if we are hitting up the high tide line or getting deep into the lake. Some areas might have way higher concentrations of microplastics than others.

Veronica collecting a sediment sample for the Dutch Sampler
Veronica collecting a sediment sample from the Dutch Sampler

To scoop up those sediment samples, we are using this tool called the Van Veen grab sampler. It is basically a stainless-steel clamshell bucket that we drop in the water. We can dig about 5-10cm deep and get a sample that is roughly 500g in size. It is not too heavy, weighs around 3kg and is not some high-tech fancy gadget. The grabber was actually invented in 1933 by Johan Van Veen, a Dutch engineer.

WAI have been borrowing a Van Veen grab sampler from the local company Van Walt.

What happens after that?

So, once we get those samples, we are filtering them out and start sorting through all those microplastics. We’re looking at their size, colour, shape, and counting them up. But we are not done, we are going to analyse them chemically to figure out exactly what we are dealing with.

3) A Simple Sieve – low tech, high impact

Our hero of the hour for sampling has become the sieve method. Originally purchased for soil sampling in the early days of WAI, we’ve taken the two smallest micron sieves and turned them into microplastic sampling machines. At 63 and 125 microns, these collect more teeny tiny fibres than the mighty manta trawl.

We take 50 litres of water in each sample and sieve it through both at once before carefully backwashing the contents of the sieve into a jar and transporting this back to the lab for filtering and analysis under the microscope.

More practical than transporting litres of water around the countryside and producing some effective results.

A Teeny Tiny Truth logo


Here you will find our updates (going backwards in time).

November 2023 – Teeny Tiny Truth with the teeny tiniest tamariki in our community

Always a highlight for the education team to head out with pre-school explorers. This time it was the Kānuka kids of Riverside ECE and we went out to sample the upper lagoon, right in their backyard. So many wonderful conversations about the difference between different materials and how long it might take plastic to break down in the environment. As we took samples from the lagoon we kept an eye out for potential sources of contamination and revisited the work we did last term around our drains being streams.

October 2023 – Stunning Spring Sampling

Sampling at the end of October 2023 was a welcome contrast to winter. Four epic days out on the lake were filled with sunshine, science and plenty of laughs. Our trustee Jeff took Veronica and our team of volunteers out at the beginning of the week and his stories and knowledge of the lake were given rave reviews by the team. We had a full volunteer team for a trip up to Makarora later in the week and as the photos attest to, it’ll be hard to beat come summer.

This round Veronica only used the sieve method making for a little less time looking down the microscope during the analysis process.

October 2023 – Here for the community

On a very wet Saturday morning in mid October, we held a community launch for the Teeny Tiny truth. An opportunity for community to come and chat to us, have a go at sampling, and be reminded of the solutions our community are working towards to become plastic free. It was amazing to have Plastic Free Wānaka share the tent with us for this event, a reminder that it’s not all doom and gloom, there are very real and practical everyday swaps we can make to move towards a plastic free tomorrow.

Expectations were low as the rain set in early morning but as luck would have it, just as we opened the ‘doors’ the sky cleared and we had a fabulous day out with the community chatting about the Teeny Tiny Truth. Myths were dismissed about microplastics just being those beads that used to be in the facewash scrubs as we found synthetic fibres in the water samples around the dino park. For more details of the event: Sampling for microplastics with the Wānaka community.

Water fIltering method
Veronica with a different filter

August 2023 – Winter sampling round

After completing a successful pilot, we were out on the lake for 8 days during August. 96 hours of volunteer support, in-kind fuel and gear from Lakeland Wānaka allowed Veronica to get out to all 10 sites and complete sampling using four different methods:

Trawling for plastics using the Manta Trawl, collecting water straight into 5 L glass containers for filtering back in the lab and two sieving methods, one being backwashed in-situ on the boat and the other collecting the mesh in a jar to be removed using ultra sonic vibrations back in the lab.

Volunteers in action
Volunteer filtering water
Volunteers on a boat

Although there were some long, cold days… the sun was shining and there is something magical about being out on the lake on cool, calm winter days. So many different community volunteers were able to get hands on with the research, right alongside Veronica!

July 2023 – Collaborating with Wastebusters for Plastic Free July

A highlight of the project so far was connecting with the community for the first time at the Wastebusters plastic free July green drinks event. Veronica and Jose spoke about the project and started asking the community what they expect we might find. We also partnered with Wastebusters to host a local teachers afternoon and began to understand how the project might link to local curriculum and schools.

First water sampling net for the pilot project
Sediment sample in a jar

June 2023

Pilot out on the lake – two days, Veronica, WAI and volunteers – 4 sampling methods at 9 different locations. Including trialing sediment samples at 30m depth with the Dutch sampler.

April 2023 – Funding is here!

We are thrilled to announce we have received funding to support microplastics research here in Lake Wānaka – the first of its kind in our community! We are incredibly grateful for the support of our funders for this project: The Otago Participatory Science Platform, Curious Minds, Ten Square Games and Planet Play.

A Teeny Tiny Truth banner

A Teeny-Tiny Truth – exploring microplastics in our freshwater

Microplastics are a hot topic these days – the word refers to fragments of any type of plastic less than 5mm long. Many studies suggest they impact both human and aquatic health.

How much do we currently know about microplastics in Aotearoa’s lakes and rivers? The answer is simple – not a whole lot!

This project, titled A Teeny-Tiny Truth, has two big objectives:

  1. Collecting data on microplastics in Lake Wānaka.
  2. Empowering our community to get involved in the process and creating change.

Will you join us? Stay tuned as we embark on this important journey!

Microplastics suspended in water


Veronica Rotman
Veronica Rotman

(University of Auckland, University of Otago – Department of Marine Science)

Veronica is a marine scientist, current doctoral candidate and science communicator with a background in microplastics research. She sits on the Sustainable Seas National Science Challenge Stakeholder Panel and tutors and lectures at tertiary institutions in New Zealand. Veronica set up and delivered a tertiary education program in remote Kaitaia, teaching sustainable aquaculture and marine science to representatives of the Muriwhenua. Some of her prior research investigated whether one of our most commercially valuable fish species, hoki, is consuming plastic in the wild and what effects plastic ingestion has on the physiology of NZ’s beloved snapper.

Veronica’s PhD project is titled Ki uta ki tai (mountains to sea): plastics in Southern Aotearoa. It investigates sources of pollution, how it’s distributed, and potential threats to culturally significant taonga species from the mountains of Wānaka to the ocean and offshore islands of southern Te Waipounamu. She passionately loves the great outdoors, freediving, ski touring, and exploring.

Dr Bridie Allan
Dr Bridie Allan

(University of Otago)

Dr Bridie Allan’s research explores how environmental changes can alter the mechanisms underlying population processes and how these changes scale to community dynamics.

To do this, Bridie uses field collections, observations and experiments in conjunction with laboratory experiments to investigate a wide range of impacts including climate change, oil pollution, habitat disturbances, microplastic pollution, and other human activities that influence the physiology, behaviour and survival of fish. Bridie’s study sites span both tropical and temperate ecosystems.

Community in-kind support

Thank you to the kind businesses who support this project. We couldn’t do this without you!

Aspiring Glass cut glass jars for the project to use as filters for one of the four trial methods.

Lakeland Wānaka gave a free boat hire for the entire day for sampling.

Select Engineering found us the perfect bolt to attached the flow meter to the Manta Trawl.

Van Walt lent us a Van Veen grab to take sediment samples for the pilot round.