Microplastics showing up in seafood along North Coast

Tiny bits of plastic are turning up in grocery-store oysters, fish larvae, even Arctic ice cores.

Esther Anna Gies

Esther Anna Gies

Tiny bits of plastic are turning up in grocery-store oysters, fish larvae, even Arctic ice cores.

“The bottom line is they’re very small particles, but they have an impact on larger animals right up the food chain,” Esther Anna Gies, a marine biologist who researches ocean pollution with the Vancouver Aquarium, said.

“And microplastics are everywhere.”

Speaking at the Kay Centre on June 8, World Oceans Day, Gies gave a Gwaii Haanas talk called Understanding Microplastics: From Land to Sea.

Microplastics—any plastic fibres, bits, or beads smaller than half a pinky fingernail—are one of several pollutants that Gies and her colleagues have started tracking in  mussels and underwater sediments at seven sites around Haida Gwaii, and dozens more along the B.C. coast.   

One study found that microplastics can absorb toxins such as flame retardants or PCBs, then leach those toxins into fish.

Another found that when larval perch swim among tiny bits of polystyrene, or Styrofoam, they tend to eat it instead of zooplankton—a strange diet that makes them less active and oblivious to predators.

Researchers also discovered that when zooplankton eat microplastics, much of it ends up in their poop. Buoyed by the microplastics inside, the feces doesn’t sink as it normally does into the water column, where it usually nourishes algae and bacteria.

“It could have an impact on the whole food web,” said Gies.

Still another study found that viruses and bacteria like to grow on the surface of microplastics because like all plastics, they tend to repel water, making their surface easy for microbes to cling to.

Gies, who did her PhD in microbial genomics, said researchers are now looking to see if harmful bacteria or virus-covered microplastics might spread disease over ocean waters.

So far, Gies said no one has found a way to filter microplastics out of ocean water without also sweeping up tonnes of tiny sea creatures.

Nor has anyone found a “super bug” that can digest microplastics in anything but highly specialized lab conditions.

Given the difficulty of getting microplastic out of the ocean, much of the effort to get rid of it is focused on preventing it from getting in.

Gies pointed out that similar efforts have worked before.

In 1989, regulations on the effluent of B.C. pulp mills led to a 95 per cent drop in dioxins—a highly toxic and persistent chemical compound.

In the Lower Mainland, the  Vancouver Aquarium is working with wastewater treatment operators to try and develop filters that stop microplastics from getting into the ocean.

By 2019, Canada has proposed to ban the sale of household products with microbeads less than 2 mm—the little polystyrene beads are often found in facial scrubs, toothpastes and shampoos.

Just one shower with a shampoo full of microbeads can release up to 1,900 of the tiny plastic particles.

Microplastics also find their way to the ocean via household washing machines, which rinse away lots of lint containing tiny rayon, nylon, and other fibres from synthetic fabric.

While it seems most microplastics concentrate close to urban areas along the B.C. coast, Gies said they do get swept up by currents—one surprising hotspot is in Queen Charlotte Sound.

Each of the world’s five oceans now has a concentrated gyre of micro- and macroplastics—the largest, in the north Pacific, is about the size of Texas.

With about 350 million pounds of plastic today, by 2050 the oceans could have more pounds of plastic than fish if nothing is done to change course.

Sounding an optimistic note, Gies pointed out that anyone who cleans big, visible macroplastics off the Haida Gwaii shoreline can do a lot of good.

“If you pick up a large plastic item off a shoreline, you make a contribution,” she said, noting that over time, all those buoys, bottles and synthetic ropes would otherwise shed or break up into millions of microplastics.

Gies also noted that when it comes to plastics in the ocean, many of the worst offenders—cigarette filters, food containers, bottles and  caps—come from single-use items that shoppers can avoid.