Die-off of hundreds of snails brings foul smell to Lake Micmac

CBC

11 hours ago

When Patricia Mombourquette was getting ready for a swim in Lake Micmac last week, she was greeted by a foul stench and the unsightly presence of hundreds of dead snails that had floated to the surface.
What initially looked like small black dots and a film on the lake was likely an invasive species known as the Chinese mystery snail, which is also called a trapdoor snail.
"It's a putrid smell that's nauseating," said Mombourquette, who has only been living in her lakefront Dartmouth, N.S., property for a few months.
The Nova Scotia Invasives Species Council says it has been receiving more reports lately of the Chinese mystery snail appearing in ponds and lakes.
The snails most likely found their way into native ecosystems by being released into lakes and ponds by aquarium keepers trying to get rid of them. A single female can give birth to over a hundred baby snails, so the population grows quickly.
Introducing aquatic species into ponds and lakes is illegal under the federal Aquatic Invasive Species Regulations.
Mombourquette contacted the Department of Fisheries and Oceans to report the incident.
In a statement to CBC News, DFO said mass mortality events are common for Chinese mystery snails in freshwater environments with large populations.
"Mortality events can also be caused by environmental conditions, such as low oxygen levels, fluctuations in water temperatures, and other factors," it said. "DFO does not expect any long-term environmental impacts following this mortality event."
It said the decomposition of snails is what's causing the stench.
Mombourquette said she wasn't sure if this experience was a recurring thing, so she asked her neighbour, Louise Jessome.
"I've never seen it before and ... I've been on that lake for 48 years," said Jessome.
She waited to see if the smell and the snails would disappear on their own. But on Friday, Jessome took matters into her own hands.
Armed with gloves, a garbage bag and her boat, she went to the dock to remove the snails. After 30 minutes, she had filled a third of the bag, but more snails were still floating on the lake.
"It's just rotting fish, what it smells like," said Jessome.