Jul 1, 2019 7:00 AM

How Remote Lakes Could Help Unravel the Mysteries of Microplastic

The Experimental Lakes Area is a one-of-a-kind platform for potentially testing how omnipresent microplastics are stressing ecosystems.

The microplastic menace is a maddening conundrum: The pollutant shows up everywhere, but science knows very little about it. Microplastic particles blow to the peaks of pristine mountain ranges. They swirl hundreds of feet deep in the sea. They clot ocean critters, from shellfish to regular fish.

Yet we have little data on how microplastic might be affecting the animals exposed to it, and we certainly don’t know how the stuff could be affecting whole ecosystems. A system of small, isolated lakes in Canada, though, could help unravel those mysteries. The International Institute for Sustainable Development’s Experimental Lakes Area, or ELA, are testing grounds that allow researchers to isolate a pocket of water within a lake and add pollutants like hormones and flame retardants—and now potentially microplastics—and watch how the ecosystem responds. The microplastics program is in its very early stages, but it could turn into a one-of-a-kind platform for testing how this omnipresent pollutant might be stressing ecosystems.

Studying lakes is pivotal because the ocean doesn’t lend itself well to controlled experiments. Researchers can’t dump a bunch of microplastic out there and say, Aha, look what’s happening to these fish and these algae and these crustaceans. In the lab, sure, you can put fish in microplastic-tainted water and see how they fare compared to a control of fish kept in normal water, but that’s not replicating the extreme complexities of a wild ecosystem.

“When we raise animals in the lab, it's essentially a five-star hotel,” says University of Toronto ecologist Chelsea Rochman, co-lead on the microplastics work in the ELA. They get all the food they need and live with other organisms they’d get along with in nature. The only stress researchers add is the microplastic, whereas in nature all manner of stressors conspire to ruin a creature’s day.

“So temperature, light, abundance of food, competition with other animals for prey, predation,” Rochman says. “Something that has an impact in the lab might have a different impact in the field, because it's competing with other factors.”

But a controlled area inside a living, breathing lake can make for a more realistic environment. On top of that, the 58 small lakes in the ELA system are situated in nearly human-free northwestern Ontario, meaning they should be largely free of human pollutants. Except, that is, for microplastics potentially blown there by the wind. So this summer, the ELA team is beginning microplastic research by sampling background concentrations of particles in nine lakes.

The researchers hope to use this information to inform future manipulative experiments using microplastics at ELA, which could entail floating collars that form a sort of huge outdoor aquarium. “Imagine if you were to put a very large bag that's open to the sediments in the water column,” says Lakehead University biologist Mike Rennie, co-lead on the microplastic research. This sheeting is held at the bottom with sandbags and attached to the floating collar, which forms a structure extending from the shore. “So what ends up happening there is you have a mini ecosystem within the ecosystem.”

A recent project testing selenium.

IISD Experimental Lakes Area

And in would go the microplastics. The researchers could also extend their contained ecosystems onto the shoreline to include the land-water interface. For example, might amphibians, which straddle this interface, act as vectors to bring water-going microplastics farther up on land?

The big, overarching goal would be to see what effects microplastics have on organisms and how those effects propagate through the ecosystem.

As Rennie knows from experiments with other substances in these lakes, the results can be surprising. “One of the things we've consistently found in our experiments at ELA is you almost always end up with unexpected impacts through indirect effects,” Rennie says. “So, for example, when we added synthetic estrogen to a lake, it ended up turning a bunch of the fathead minnows intersex, so the males turned into females.” Bad for the fathead minnows, obviously, because they couldn’t breed, and consequently their population crashed. But also bad news for lake trout, which relied on the minnows as prey. So even though the trout weren’t responding directly to the estrogen, the estrogen was imperiling them by proxy. Might microplastics also cause other surprising ripple effects?

That’s going to require careful experimentation at ELA, but what we can say for sure is that microplastics are everywhere. “Every single fish we've looked at in the lab has microplastics, and in individual fish we've seen more than 100 particles in the gut content,” Rochman says. “It's definitely important to try to understand how that might be impacting organisms.” And in turn, how those potentially compromised organisms might be compromising the species around them, like a zombie virus tearing through a population.

IISD Experimental Lakes Area

Speaking of viruses. Microplastic particles may also be acting as vectors for disease in the environment by transporting pathogens. And the harm caused by microplastics may extend beyond the particles themselves: In the lab, researchers have found that the chemicals leaching out of microplastics may be compromising oceanic oxygen-making bacteria.

In the lab being the operative words there. That kind of research is an indispensable first step toward decoding one of the many potential threats microplastics pose. But without studying the ocean itself, we can’t say for sure that leachates, as these chemicals are known, are a problem yet. The data that’s showing adverse effects from microplastics is coming from the lab, not from the natural world, where researchers are typically limited to quantifying the abundance of particles.

The beauty of ELA is that it unites these two kingdoms. “It's one of the only places you can do that in the world,” says University of Michigan eco-toxicologist Allen Burton, who studies plastics. “It's the perfect outdoor lab. It's a shame we don't have more systems like this around.”

The microplastic menace is pervasive, and it is stubbornly mysterious. But by experimentally tainting portions of these isolated lakes, perhaps we can prevent future, more widespread, losses.