Invasive green crabs that have caused major problems for native species like eelgrass at Nova Scotia’s Kejimkujik National Park Seaside could be the latest solution to reducing plastic pollution in the ocean.

Parks Canada has teamed up with a McGill University professor to find a way to turn the shells of the pesky crabs into a biodegradable plastic that could be used to make cutlery, cups or plates.

Crabs harvested from the park just south of Liverpool, N.S., will be shipped this spring to Montreal, where Audrey Moores has developed a non-toxic way to transform a polymer naturally found in crustacean shells into a hard, opaque plastic-like material.

“What we know is that if we take regular crab shells, shrimp shells, lobster shells, we have very good results, so we’re fairly confident that the green crab should not be different,” said Moores.

Unlike regular plastic, the material that Moores is left with will degrade in the ocean. But more research is needed to find out just how long that process will take, Moores said.

It’s exciting research for Gabrielle Beaulieu, project manager for the eelgrass conservation restoration project at Kejimkujik Seaside. She stumbled across it recently and wondered if it could help in Kejimkujik’s decades-long battle with green crabs.

“Invasive species may be detrimental to the ecosystem, however there’s always surprise solutions that we have to be open to,” Beaulieu said.

European green crabs have been wreaking havoc on eelgrass and soft shell clams at the park since the 1980s. They first arrived in North America in the ballast water of ships from Europe in the 1800s and have been on the move due to warming oceans.

There are now just a handful of spots in Atlantic Canada without green crabs, Beaulieu said.

“If we can make this invasive species come full circle as a solution to the plastic pollution issue that all the oceans are facing today, I really think that’s going to be such a great and innovative way to figure out the invasive species problem,” she said.

Thanks to initiatives like the ecotourism campaign Gone Crabbin’, two million green crabs have been hauled up at Kejimkujik Seaside Park since 2010, said Beaulieu. 

Now, there’s a year-round place for them to go.

“We’re really hoping that this project demonstrates an innovative new way of dealing with invasive species,” she said. “Certainly as climate change is upon us, there may be more introductions of marine species that we still know nothing about.”

The power of chitin

The key to creating biodegradable plastic from green crabs lies in chitin, one of the main components in crustacean and insect shells.

Moores, an associate professor in McGill’s chemistry department, crushes the shells to get to the chitin. She then uses a special method she’s developed to transform the polymer into a material that will withstand water.

“So now you can make a cup out of it that will hold the water because the cup itself is not going to be dissolved by the water,” she said.

Right now, the plastic material that’s created is hard like glass, but Moores said her team is hoping to find a way to make it bendable so it could be formed into disposable cutlery and other single-use items.

How many crabs are needed?

The first batch of crabs will go to Moores’ lab in Montreal this spring, but then the work is moving to Nova Scotia where production of the biodegradable plastics will ramp up.

Moores, who visited Nova Scotia last summer, said it’s unclear exactly how many crabs would be needed for each cup, but estimated that could mean hundreds of crabs for many kilograms of biodegradable plastic.

She’s currently looking for a full-time researcher to help with the work.

Eelgrass making a comeback

Beaulieu said Parks Canada will never be able to eradicate green crabs at Kejimkujik Seaside, but they’ve been able to control the population so native species like the eelgrass can begin to adapt to the intruder.

She said green crabs had decimated all but two per cent of the eelgrass that was at the park in 1987, but that thanks to conservation efforts, about 34 per cent has been recovered.

Last summer, when tourists ventured out in boats and hauled up crab traps, Beaulieu was able to tell them that the trouble-making crustaceans could one day be put to good use.

“Most people were a little bit in a state of disbelief that that was even possible,” she said. “But a lot of people were really excited to learn that there are solutions to plastics, as well as invasive species, that we still haven’t even thought about.”

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