Trawling for Microplastics: eXXpedition Great Lakes 2016

UM scientists use manta net to trawl Great Lakes for microplastic pollutants

On August 20, 2016, eXXpedition Great Lakes 2016 set sail on the Great Lakes on a mission to make the unseen seen by leading the world’s largest simultaneous water sampling project for microplastics!

The 7 lead boats (on Lake Michigan, Lake Erie, Lake Ontario, Lake Huron, Lake Superior, Lake St. Clair, and the St. Lawrence River) had female captains and all-female crews consisting of scientists, activists, artists, sailors and most importantly, residents of the Great Lakes. These boats led the day – conducting water sampling and trawling for microplastics.

Microplastics are small plastics (less than 5mm in diameter, generally) that are being found, sometimes in large quantities, in oceans, lakes, rivers, and on beaches. They are potentially dangerous because they can adsorb toxic chemicals and then transfer them to aquatic creatures when the plastics are ingested. Microplastics take several different forms: beads, fibers, and irregular bits. The beads are produced commercially and used as abrasives in things like face wash and toothpaste. However, with the upcoming federal ban on microplastic beads in personal care products, we've made some good progress there. Fibers, which make up a large amount of the microplastics sampled in the Great Lakes so far, are a trickier problem. Fibers get washed off of clothing, like fleeces and active wear, and then end up in the water system if waste water treatment plants can't filter them out. These fibers have been found in the muscle flesh of fish in the Great Lakes. This water sampling project (eXXpedition Great Lakes 2016) had two purposes: raise awareness of the problem of microplastics in the Great Lakes and gather wide-spread data on how much microplastic is in the Lakes. After the samples are processed and we find out what plastic (and what type) was where, all that data will get added to our growing body of knowledge of how plastic is moving through the Lakes. From there, we can look at the best ways to prevent further plastic pollution and how best to clean up what's already there.

Dr. Laura Alford (NA&ME) and Prof. Melissa Duhaime (Ecology and Evolutionary Biology) were co-Lake Leads for Lake St. Clair.“We were originally going to do the 5 Great Lakes and the St. Lawrence River,” said Alford. “But because of all the work I’ve been doing on fish spawning reefs in the St. Clair River and the Detroit River, I’ve come to appreciate how critical Lake St. Clair is to the Great Lakes ecosystem. Melissa agreed, and so we volunteered to be co-Lake Leads for Lake St. Clair.”

Alford & Duhaime’s lead boat, captained by MJ O’Brien of Ann Arbor, used a manta net to trawl for microplastics. The manta net consists of a 100 micron net attached to an aluminum frame with a flow meter mounted inside. The manta net is towed either behind the boat or off to the side, depending on available mounting for the manta net. “This was the first time I had gone on a sampling mission,” said Alford. “Melissa was the science lead, and she showed us how to do the initial processing of the sample. The net is very fine, so you catch grass, sand, insects, algae, trash, and other things in addition to the microplastics.” The crew used a series of filters to remove the large debris. The remainder of the sample was placed in a bottle that will later be sent off to a lab to be analyzed for the type of microplastics present and in what amounts. “You rinse and rinse and rinse some more!” said Alford, laughing.

The community-led initiative was open to everyone in the Great Lakes region of America – male and female, adult and child, solo or in groups – and they all took part to stand up for the health of the Great Lakes. “People go on vacation, and they look out at our beautiful lakes,” said Alford. “They are so gorgeously blue and green and teal and BIG, with wonderful sandy beaches to walk and swim or rocky beaches where you can hunt for Petosky stones, fossils, or just cool rocks. You’d never think that they’re actually a delicate ecosystem in danger from us. But if we take care of them, they’ll take care of us.”

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