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Invasive Chinese Snail Threatens Canada’s Lakes and Waterways

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Published: March 17, 2022
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Invasive Chinese snails are slowly emerging in a lake in Alberta, Canada, posing a growing concern that may require containment to keep them at bay. (Image: Judy Gallagher via Flickr CC BY 2.0)

An invasive species is one that is introduced to an environment different from its native home, and greatly affects the new ecosystem. Oftentimes they are purposely introduced by man for one purpose or another. Other times, they are transported by accident, or are perhaps “stowaways” on ships. All of the above may have played a role with the invasive Chinese snail recently discovered in Alberta, Canada.

The Chinese “mystery” snail (Cipangopaludina chinensis) is a large snail with a tough shell that grazes river bottoms and lakes for algae and other plant material. It gets it’s name due to the live birth of young, in that they “mysteriously” appear. Addressing concerns that this invasive Chinese snail may threaten its new habitat, scientists are recommending containment as the best solution to keep them from spreading, because this snail is as impenetrable as a bomb shelter. 

These snails are tough as nails

In 2019, the first Chinese mystery snail in Alberta was first discovered in McGregor Lake, south of Calgary. These mystery snails have also been found in other parts of British Columbia, eastern Canada, and the U.S. 

No one knows when or how exactly these snails migrated to the reservoir. Megan Edgar, a master of science student at the University of Alberta, believes that “human release or accidental transportation” from British Columbia or the East Coast may have been responsible.

Chinese mystery snails were first brought to the U.S. in 1892 as a delicacy, entering live food markets in San Fransisco. By the 2000’s, notable populations began to pop up in the wild. 

“There’s so many different factors that can actually transport an invasive species, so it’s really hard to pinpoint where they actually come from,” Edgar said.

With the arrival of the Chinese mystery snail in McGregor Lake, it presents a potential problem to the ecosystem, as is often the case with invasive species. 

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According to Edgar, the mystery snail is larger than the native snails, growing to about three inches tall. Its size allows it to outcompete smaller snails for food. 

“Chinese mystery snails change the algae composition of the lake, and they might eat more of the algae, leaving less food for our native species,” Edgar explained.

Altering one aspect of the habitat alters the entire environment. As the mystery snails deplete the native snails’ food source, this would dramatically affect the whole aquatic food ecosystem. 

However, an even bigger problem is that the Chinese mystery snail boasts some incredible defenses. Nicole Kimmel, an invasive species specialist with Alberta Environment and Parks, said these snails have a trapdoor mechanism—the operculum—to protect it from outer threats.

“They’re quite tricky because they have this trapdoor that can seal up the snail shell completely for weeks at a time,” Kimmel explained. 

This durable mechanism is so resilient that the snails can live for nine weeks without water, survive exposure to chemicals, and ward off predators. Edgar also said that the snail shell acts as camouflage in the riverbed.

“So, this makes them pretty tough against any kind of predation,” Edgar said.

The mystery snail can survive almost anything and arel likely to overwhelm other snails in time. 

Although they produce fewer offspring than Alberta’s native snails, the invasive Chinese snails still reproduce around 19 snails in 15 months. 

In addition to disrupting the food chain, the mystery snail can also clog water pipes and spread disease to other aquatic wildlife, Wisconsin-based conservation research program Sea Grant stated on its website.

Containment is key

Containment is currently the best option to stop the invasive Chinses mystery snail from spreading, but scientists are looking for other options. (Image: Judy Gallagher via Flickr CC BY 2.0)

As the invasive Chinese snails are becoming a growing problem, scientists like Edgar are racing to find a solution to keep the snails from extending past their boundaries. Currently, the best strategy is simply to contain the snails until a breakthrough is achieved.

There is currently a ministerial order at McGregor Lake, encouraging watercraft users to “clean, drain and dry their gear” to prevent snails from hitching a ride on their boats.

“If people come to the lakes, make sure that you clean, drain and dry all your gear and make sure they’re not on your boat. If you see them, contact the Alberta Invasive Species hotline and let the government or researchers know what you’re seeing,” the order states.

Since the mystery snails have a long lifespan of four years, they may live long enough to be transferred to different bodies of water if they are not removed. 

“The impacts to the ecosystem seem quite high, so we don’t want to jeopardize any of our native mollusks or fish habitat, so that’s really the goal,” Kimmel said.

Ila Bonczek contributed to this report.