Researchers in Sitka have been looking at the impact of microplastics on local shellfish. Their findings illustrate a possible connection between microplastics in butter clams and household laundry.
Helen Dangel sits in her office at the Sitka Tribe of Alaska research building. The fisheries biologist is dressed like one: She wears a white lab coat and looks at slides through a microscope.
She peers down at a sample from a butter clam. She spots three pearls, each about a millimeter in size — so small you can barely see them with the naked eye.
But she sees something else under the microscope — something less natural. It looks like a hair, but it’s actually a tiny piece of plastic: a “microplastic.”
As the name suggests, microplastics are miniscule pieces of plastic debris, and they’re littering the world’s oceans. Consumed by fish and wildlife, microplastics could have unhealthy consequences. The research into health effects from ingesting microplastics remain inconclusive. But nobody’s saying it’s good.
That’s one reason why Dangel and fellow researchers have spent the past year collecting samples of two marine species — butter clams and blue mussels — looking for microplastics in the mollusks. In partnership with Mt. Edgecumbe High School and University of Alaska Southeast, they collected samples from Starrigavan Estuary, north of Sitka, in 2018.
There’s been a nationwide backlash against one major source of plastic pollution: plastic bags. And cities in Alaska like Wasilla, Soldotna and Cordova have banned single use plastic bags. Anchorage moved to ban them last year, though the roll out’s been delayed.
Sitka flirted with the idea of a fee on plastic bags, though the Assembly postponed action indefinitely.
Dangel explained that plastic bags do break down over time – but they don’t really go away.
“The idea is that most microplastics are from larger pieces that are floating around in our environment. It is plastic bags and bottles that break down,” she said.
After researchers collected the shellfish, they returned to the lab, measured the clams and mussels and then separated their bodies from their shells. Using potassium hydroxide, the researchers chemically digested the soft-body tissue of the shellfish. Then they put the tissue in flasks in an incubator shaker for 24 hours to accelerate the chemical digestion process.
“Once they’re incubated, they turn into a yellowish fluid,” Dangel said. “We filter those out onto small filter circles that we can examine under a microscope.”
They discovered that, in both samplings, all of the butter clams and most of the mussels contained microplastics.
Dangel said that the majority of the microplastics they found weren’t plastic fragments — they were “microfibers.” They look like tiny, synthetic hairs.
So where are they coming from, and how did they get into the ocean?
Dangel said they’re likely from synthetic fabrics, like polyester or nylon. It could be Sitka’s dirty laundry.
“When we wash our clothes here in Sitka, where does it go?” Dangel asked. “It goes from the laundry wastewater into our wastewater system, through our pipes. It goes over to the sewage treatment plant, and it’s treated, but they’re not able to remove those really small fibers. So it just goes right into our ocean.”
Dangel said there are products on the market that collect microfibers to reduce pollution in the water supply.
Microplastics are found everywhere, both in farmed fish and wild stocks caught in Alaska. But Dangel said it’s not a reason to stop eating wild seafood.
“If we stop eating our local salmon, are you going to buy a steak that is high in saturated fat and not as good for you?” she asked.
But with Alaskan seafood marketed as some of the most pristine wild-caught in the world, this research showing microplastics in shellfish is troubling. The next step, Dangel said, is to examine other species, like salmon.
But for now, she hopes her research will make people more mindful about synthetic fibers. Because microplastic pollution that goes down the drain doesn’t really go away.
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