Q&A Great Lakes plastic

The Great Lakes often get overlooked when it comes to aquatic plastic pollution, with ocean plastic taking up more space in the news. But as the University of Toronto’s Rochman Lab has found through its studies of anthropogenic pollution, including plastic and its impact on toxicity in lakes and rivers, the plastic problem is of equal concern in the world’s largest freshwater reserve. Kennedy Bucci is a PhD student at the lab, where she researches the effects of microplastics on fathead minnows, a fish present in much of North America. She spoke about why it’s in our interest to pay attention to what happens when plastic flows into lakes Superior, Huron, Michigan, Erie and Ontario in this exclusive interview. 

Why is it important to study and learn about plastic pollution in the Great Lakes? 

We depend on the Great Lakes for drinking water, food and fisheries and tourism. But because the lakes are smaller than the oceans, there’s a higher concentration of pollution per area. And the higher population numbers around the lakes leads to more direct pollution from urban centres. 

How do you measure the amount of plastic in lake water?

We tow a manta trawl — a cone made of a 300-micron mesh — behind a boat, then rinse the contents collected in the cone and separate out the algae, zooplankton and wooden debris from the plastic. The amount and type of plastic in that sample are determined using microscopy and spectrometry, and if we know the flow rate for the manta trawl we can calculate the volume of plastic in the water. 

Are larger macroplastics items of more concern than microplastics? Or are they comparable in terms of the harm they cause?

Macroplastics, because of their size, are more of an immediate threat in that they can cause direct damage to, for instance, birds when they get stuck in plastic rope or bags. Microplastics cause harm on different levels; if a fish eats tiny plastic particles, it can lose its ability to feel hunger because its stomach is full of plastic that can’t be digested. Microplastics can also have sub-lethal effects, which is when they act as a magnet for chemical pollutants, adsorbing flame retardants and heavy metals. There’s a tendency for plastic to adsorb chemicals, which then make their way into fish.

What have you found so far in your investigation of microplastics and their effect on the health of freshwater fish?

My work focuses on the sub-lethal effects of plastic pollution on fathead minnows, which are an important food source for other species higher up in the food chain. In the lab, I keep tanks of minnows; the fish in one tank are exposed to polyethylene made from pre-production virgin materials, while fish in another tank are exposed to plastic collected from Lake Ontario. The Lake Ontario plastic contains chemicals that were added during the production process as well as adsorbed chemicals. Over a two-week test, I found deformities in the fish exposed to Lake Ontario plastic — their spines were bent, their tails were crooked and they had smaller eyes. The next step in the investigation is to carry it over to the full life cycle of the fish. 

What concerns you when it comes to plastic pollution?

The lack of awareness. I sometimes speak at events on plastic waste and bring lint with me from the washing machine to show how much microplastics shed from clothing, and a lot of people have no idea. People have also told me they put dryer lint in the compost, not realizing it is plastic that will make its way into the soil.

Another concern is that people think action on an individual level won’t make a difference, so I try to help them understand that individual actions do help — they add up over time and can lead to a chain reaction that eventually puts pressure on the producers to change or reduce the amount of plastic they manufacture.

There’s also a lot of greenwashing around, for instance, biodegradable plastics. What people don’t realize is that many of these plastics are only biodegradable if you apply high heat or bacteria or enzymes or chemicals, which make them less than environmentally friendly or give them a bigger carbon footprint. If you want to buy a biodegradable plastic, make sure it is compostable in your own compost. Do your research — in the end, you might spend more money for a so-called biodegradable plastic fork than you would for a regular metal fork that you can use over and over again.