Four years into a volunteer-led program removing invasive Chinese mystery snails from County lakes and Paul MacInnes, chair of the Coalition of Haliburton Property Owners’ Association (CHA), said almost 1.4 million critters have been evicted to date.
Speaking at U-Links celebration of research event March 29, which took place virtually due to the weekend ice storm, MacInnes said the effort is going strong. Launching in 2021 with 235 volunteers, he said 425 people were active on 41 County lakes last summer.
He expects that number to grow again this year. For participants, it’s not as simple as turning up with a can-do attitude, there’s training involved on how to properly handle and dispose of the snails.
MacInnes said the snails have been a major problem on lakes through the Trent Severn Waterway system for decades.
“They’re not like normal snails, which lay eggs that are eaten by fish. These snails are born in their shell, so it makes them very resistant to being eaten. Females can give birth to up to 100 juveniles a year.
“They are a threat to lake and human health because they force out native species, they’re a vector for parasites, cause swimmer’s itch and reduce recreational pleasure on lakes,” MacInnes said.
Last summer, he said one group on South Lake collected over 80,000 snails in a single day. The species originated in eastern Asia, landing in North America in the late 1800s. The snails were introduced to the Great Lakes around 1931.
Given how entrenched the snails are in our lakes’ ecosystems, MacInnes said full eradication isn’t realistic. The program’s effectiveness differs from lake-to-lake.
“It depends very much on the make-up of the lake and how many volunteers are involved. On some lakes, we have made significant progress. The goal is to keep the snails under control to a point where people can go swimming.
“For lakes I’ve visited, it’s much better with this control than on lakes where there’s no volunteers collecting. On those lakes, it’s basically impossible to go for a swim now,” MacInnes said.
More monitoring
Dr. Pedro Antunes, an invasive species and climate change biologist teaching at Algoma University in Sault Ste. Marie, provided a high-level overview of plant-based and insect invasives at the event.
He said there’s a correlation between climate change and the onset of some invasive species. Antunes noted the average temperature in Canada is 1.1 degrees Celsius higher than pre-industrial levels. In some northern areas, the change is closer to 1.5 degrees Celsius.
“With this changing temperature, plant communities are changing,” he said, noting other contaminants like microplastics, pesticides, heavy metals, and intensive agriculture can lead to more nitrogen filtering into the ground, which he says is a negative.
Antunes said Ontario is a hot spot for invasive species in Canada, hosting the highest number of invasive plants in the country. He attributed this to overseas shipping, estimating 64 per cent of containers entering Canada come via the Great Lakes and St. Lawrence corridor.
“Most of the invasive plants come from the agricultural and horticultural sector, things like ornamental plants… we have a very good grasp of where these plants are coming from and where we need to keep vigilant,” he said, plugging a guidebook published in 2013 that identifies 14 plants and 11 insects and pathogens that are most concerning.
He and his team developed that list using data to see “what species are moving the needle more than others and then target these species for control.” Antunes said the goal is to get to a point where, through continuous tracking, scientists will be able to detect new invasive species before they spread. He said this has been done in the U.S. with some forms of algae.
“We just need better monitoring,” he said.
Community plays ‘big role’
Kayleigh Mooney, an ecological restoration student at Trent University, said community members can play a significant role in aquatic science. Speaking at the event, she shared how, when surveying Gilchrist Bay north of Peterborough, she watched a lakefront resident pulling what she thought was starry stonewort, an invasive macroalgae, from the water. After going to speak with the resident, Mooney said it was a native plant she was removing.
“By pulling them out, she was removing the buffer that could lead to more of the starry stonewort coming in,” she said, highlighting the importance of people knowing the difference between a native and non-native before springing into action.
Mooney said people who frequent a lake more often than visiting scientists can be key to understanding how invasive species adapt to and change their surroundings.
“There’s more to the story than just the species itself. The wider community and ecosystem it’s a part of is important too,” she said. “Folks have the opportunity to intimately understand and observe these relational interactions in a way researchers could never capture. We get one side of the story, but there’s a role that could be filled by the community to capture the other side. One that shows the full extent of what’s truly happening within our lakes.”
